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• The clastic rocks have multiple derivations from the Alxa Block and arcs/microcontinents in the CAOB. • A Carboniferous closure was suggested for the middle segment of the PAO. • The NAOB entered into an extensional setting during the Permo-Carboniferous. • A Permo-Carboniferous tectono-paleogeographic reconstruction was proposed for the NAOB. The Central Asian Orogenic Belt was formed by the subduction to closure of the Paleo-Asian Ocean (PAO). However, it is highly controversial about the closing time of the PAO, especially its middle segment in the northern Alxa orogenic belt (NAOB). In this study, the new and published zircon U–Pb and Hf data for the Carboniferous to Permian sediments across the NAOB have been integrated to reply the above problem. The depositional ages have been constrained as the Carboniferous to Permian by the detrital zircon ages, fossil assemblages and stratigraphic correlation. The Carboniferous sandstones are dominated by the Paleozoic zircons (mainly around 380–510 Ma) with a few Precambrian zircons. The late Cambrian to early Carboniferous zircons with positive to slightly negative ε Hf (t) values were probably sourced from the orogen itself. The early Paleozoic zircons with slightly to extremely negative ε Hf (t) values and the late Archean to Paleoproterozoic zircons were likely derived from the surrounding cratonic blocks in the south. For the Permian samples, the Carboniferous to Permian age signal is enhanced. The Permian zircons yield similar age peaks around 278–279 Ma and similar ε Hf (t) values, and thus shared a similar source. Thus, the Carboniferous to Permian sediments received detritus across the PAO, indicating the closure of the PAO. Subsequently, the NAOB entered into an extensional setting based on the detrital zircon age patterns, rift-related volcanic rocks and basin analysis. Finally, a tectono-paleogeographic reconstruction from the Carboniferous relic sea and marine transgression to Permian marine regression-transgression-regression with crustal extension was proposed. [ABSTRACT FROM AUTHOR]

[Display omitted] • The Paleo-Tethys Ocean underwent northward subduction beneath the Tianshuihai terrane during the Carboniferous–Early Triassic. • The Carboniferous–Permian magmatism was continuous in the Western Kunlun orogenic belt. • The Mazha–Kangxiwa Paleo-Tethys Ocean was closed at the Middle Triassic. The Western Kunlun orogenic belt in the northwest Tibetan Plateau is composed of the North Kunlun, South Kunlun, Tianshuihai, and Karakorum terranes, and has records about the tectonic evolution of the Paleo-Tethys Ocean. To provide new insights into the Paleo-Tethys orogeny in Western Kunlun, we present detrital zircon U-Pb and Lu-Hf isotopic data from the Late Carboniferous–Triassic sedimentary successions in the Tianshuihai terrane. Zircons with ages of 350–250 Ma are abundant in the Late Carboniferous–Late Permian samples and yielded ε Hf (t) values ranging from + 14.9 to −18.9. This indicates continuous arc-related magmatism in the Tianshuihai terrane during the Early Carboniferous–Late Permian. The Upper Permian Huangyangling Group primarily comprised Paleozoic detrital zircons predominantly sourced from the Tianshuihai terrane. Other strata contain higher proportion of Precambrian detrital zircons compared to the Huangyangling Group. This feature indicates that detritus from these strata were primarily originated from the North Kunlun, South Kunlun, and Tianshuihai terranes. We present a synthesis of provenance analysis, late Paleozoic–Triassic magmatic rocks, and Triassic metamorphic records associated with the Mazha–Kangxiwa suture zone. These data indicate that the Paleo-Tethys Ocean between the South Kunlun and Tianshuihai terranes opened at ca. 350 Ma and closed during the Middle Triassic, following continuous Carboniferous–Early Triassic subduction. Our study provides an important example of the provenance of clastic rocks in the orogen, which can be used to reconstruct information about eroded magmatic rocks and provide insights into the tectonic evolution of the orogen. [ABSTRACT FROM AUTHOR]

The Qiangtang Basin is one of the largest Mesozoic petroliferous basins in China that is still unexploited for the petroleum industry. The basic geological issues and synthesis of the Qiangtang Basin related to the Tethyan evolution are still poorly understood. This volume presents 20 research papers to address the tectonic settings, basin evolution, and sedimentary environments of the Qiangtang Basin, which are key factors for a better understanding of the overall petroleum system. The Qiangtang Basin holds a Precambrian base developed in response to the Paleo-Tethys Hol Xil-Jinshajiang Ocean evolution, with enhanced sedimentary basin infilling during the opening and expansion of the Neo-Tethys Bangong-Nujiang Ocean in the Mesozoic. The Paleozoic basin framework of the Qiangtang demised as the Paleo-Tethys Ocean closed at the latest Permian, while the Early-Middle Triassic foreland basin underwent a negative basin inversion during the Late Triassic. The latter initiated a new sedimentary filling cycle of the Qiangtang Basin, which was triggered by the active extensional rifting and the onset of the bimodal volcanic eruption. Recent scientific exploratory drilling (QK-1 well) found that the Qiangtang Basin is characterized by multiple source rocks, of which the upper Triassic Bagong Formation and the lower Quse Formation exhibit the most hydrocarbon generation potential. The development of high quality and quantity source rocks in the Qiangtang Basin is ensured by regional to global-scale bottom-water anoxia and high primary productivity in the eastern Tethys realm in the Late Triassic and the Early Jurassic. The main reservoirs in the Qiangtang Basin include the Middle Jurassic reef-beach facies, the Upper Triassic carbonates, and the Lower Jurassic terrestrial clastic rocks. Two very-thick caprocks of gypsum in the Lower Jurassic and gypsum mudstones in the Middle Jurassic strata are found during the scientific drilling, which is interpreted as favorable regional-scale seals for petroleum entrapment in the Qiangtang Basin. [ABSTRACT FROM AUTHOR]

[Display omitted] • Paleozoic deformation of the fault system in the Tazhong Uplift mainly occurred in the Middle Cambrian, Late Ordovician, and Middle Silurian to Middle Devonian. • NE-trending weak zones developed at the connective positions and bends of the deep thrust faults as accommodation faults in the Middle Cambrian. • The strike–slip faults were generated along the NE-trending weak zones in the Late Ordovician and reactivated in the Middle Silurian to Middle Devonian. • Early-stage Cambrian deformation occurred in the strike–slip faults holding high-productivity hydrocarbon wells. The Tazhong Uplift is an important petroliferous secondary structure unit in the Tarim Basin and has undergone multiple structural deformation. In the current study, we use 3D and 2D seismic data to investigate the nature of the fault system in the Tazhong Uplift. The deformation of the Cambrian sedimentary rocks in the Tazhong Uplift is generally neglected but noted in this study. We found that the Lower–Middle Cambrian rocks are involved in thrust faults. NE-trending weak zones acted as accommodation faults formed at the connective positions and bends of the deep thrust faults. The Middle Cambrian compressional stress stemmed from the northeastern margin of the Tarim Block, pointed SW, and caused the uprising of the Tabei Uplift. The second deformation occurred in the Late Ordovician. In this instance, the compressional stress stemmed from the SW direction of the Tazhong Uplift, which originated from the amalgamation of the Western Kunlun Terrane and Tarim Block. The main strike–slip fault surfaces and subordinate faults developed along the weak zones generated in the Middle Cambrian. The collision that occurred in the southeast part of the Tarim Block in the Middle Silurian to Middle Devonian resulted in the third deformation. The representative structures that occurred during this compressive deformation were the intensive NEE-trending thrust faults in the southeast of the Tazhong Uplift. The three stages of deformation played different and important roles in hydrocarbon accumulation. These strike–slip faults holding the high-productivity hydrocarbon wells generally experienced early-stage Cambrian deformation, had wide fracture damage zones in the Ordovician carbonate rock strata, and had weak en echelon faults in the Silurian to Middle Devonian clastic rocks. [ABSTRACT FROM AUTHOR]

[Display omitted] • Two stages of Cretaceous basalt erupted in the Jiurui district of the Yangtze Block. • The older basalts are Island arc basalt-like, forming from melts derived from an enriched lithospheric mantle. • The younger basalts are Oceanic island basalt-like, forming from melts derived from a depleted asthenospheric mantle. • The Cretaceous lithospheric mantle underneath the Yangtze Block was similar to EM I. The Cretaceous volcanic-sedimentary succession in the Jiurui district of the Yangtze Block contains basalts that are interlayered with fine clastic rocks, conglomerate and breccia strata. Here, we present data of whole-rock 40Ar–39Ar dating, major and trace elements, Sr–Nd–Pb isotopes, zircon U–Pb dating and Hf isotopes, and plagioclase trace element analyses to constrain the petrogenesis and tectonic background of these basaltic rocks,. Two episodic eruptions (ca. 126 Ma and ca. 91 Ma) are recognized, and the early basalts display evident enriched source characteristics such as high incompatible and low compatible elements, negative Nb, Ta, and Ti, slightly positive Pb anomaly, negative ε Nd (t) and ε Hf (t) values, higher (87Sr/86Sr) i , and high incompatible elements in plagioclase, indicating an island arc basalt-like nature. The younger basalts show low incompatible and high compatible elements, negative Rb, Pb, Nb, and Ta, positive Sr anomaly, positive ε Nd (t) values, lower (87Sr/86Sr) i , and low incompatible elements in the plagioclase, indicating an oceanic island basalt-like characteristic. The early ca. 126 Ma basalts were probably derived from a deeper and older enriched lithospheric mantle consisting of rutile-bearing garnet pyroxenite or eclogite, whereas the younger ca. 91 Ma basalts were derived from a shallower and younger depleted asthenospheric mantle constituting peridotite, with limited amounts of enriched lithospheric mantle component. The retreat and rollback of the paleo-Pacific slab and related lithospheric thinning and mantle composition transition processes probably occurred at ca. 126 Ma and ca. 91 Ma in this inland region of the Yangtze Block in northwestern Jiangxi province. [ABSTRACT FROM AUTHOR]

[Display omitted] • The sedimentary rocks of the Sayan regional stage have the earliest Cambrian age. • The clastic sediments were deposited in separate disconnected sedimentary basins. • The clastic sediments were deposited in continental and deltaic settings. • The clastic transport was from different sources, judging by the ages of detrital zircons. • The chemical data show the origin of the sandstones from different provenance lithologies. Data on petrography, chemistry, and U-Pb ages of detrital zircons have been obtained for clastic sedimentary rocks within the Sayan regional stratigraphic stage from different parts of the southern Siberia craton, namely for the Ust'-Tagul (Biryusa zone, Sayan area), Shamanka (Irkut zone, Sayan area), Ushakovka and Kurtun (Baikal area) formations. The sedimentary strata share much similarity in lithofacial patterns, with gradual transition from continental to shallow-marine facies. The analyzed lithic sandstones have poorly to moderately sorted clastic grains, with large percentages of lithic fragments (16–37 %). The lithic sandstones from different formations were deposited in continental and deltaic settings as a result of clastic transport from different provenance lithologies. The clastic material for the Ust'-Tagul Fm. deposition came from the Precambrian rocks of the Siberian craton and the Neoproterozoic (870–940 Ma) units: either the Yenisei Ridge of the craton or the Arzybey terrane of the Central Asian Orogenic Belt (CAOB). For the Shamanka Fm., it was Ediacaran and Early Cambrian material from blocks and terranes of the northern CAOB. The clastic inputs for the Ushakovka and Kurtun Fms. deposition were from the Precambrian basement of the Siberian craton and the Neoproterozoic (550–920 Ma) North Transbaikalian group of CAOB terranes. The youngest detrital zircons have the earliest Cambrian ages (530–540 Ma). The clastic sedimentary rocks of the Sayan regional stratigraphic stage dispersed over the southern Siberian craton were deposited in the earliest Cambrian in separate disconnected sedimentary basins which resulted from Ediacaran accretionary-collisional events in southern Siberia. [ABSTRACT FROM AUTHOR]

• O 2 2-O 3 1 chert and radiolarians indicate a placid sedimentary environment. • O 1-2 radiolaria indicates that the Nanhua basin was connected to ocean. • Abundances of O 2 2-O 3 1 radiolarian in Hengyang–Ji'an show the basin center. • O 2 2-O 3 1 rocks in South China should be developed in an environment of continental slope–basin. The Yanxi and Duiershi formations of the Middle-Upper Ordovician in South China are composed of black, grayish black, and dark gray thin-bedded cherts and siliceous slates, rich in carbonaceous materials and pyrite. Horizontal beddings are developed. The strata contain randomly distributed fossils. Radiolarians are discovered in the Loudi, Yongzhou, Hengyang, Ji'an and Ganzhou sections. The Radiolaria from two sections are identified as Protoentactinia sp. Abundances of radiolarian in the central area of Hunan and Jiangxi Provinces are higher than in the southern area. The strata become thickened while the amounts of siliceous materials are decreased and argillaceous contents are increased from northwest to southwest for the Yanxi and Duiershi formations. The lithology gradually changes from carbonate rocks in the north to clastic rocks in the south. δ 30Si values of chert and siliceous slate range from −0.6 to 1.18 with Al 2 O 3 /(Al 2 O 3 + Fe 2 O 3), MnO/TiO 2 , La N /Ce N , Ce/Ce*, and (La/Yb) N ratios of 0.65–0.97, 0.01–0.16, 0.99–1.27, 0.85–1.10, and 0.91–1.66, respectively. The SiO 2 and TiO 2 average contents are 89.08% and 0.27%. The SiO 2 contents decrease while the TiO 2 increase from northwest to southeast. They have similar the REE concentration with no obvious Eu anomalies. The Yanxi and Duiershi formations were deposited predominately in a bathyal environment on the continental slope–basin and the seawater was stagnant. In the Middle–early Late Ordovician, the Nanhua basin occupied a rather large area and sedimentary rocks in the region around Hengyang–Ji'an were deposited in the basin center with terrigenous source derived from the southeast. [ABSTRACT FROM AUTHOR]

• Alluvial-fan to delta-coastal environments in an initial stage of basin-fill. • Depositional breaks occurred in the late Meso- to Neoproterozoic caused by uplifts. • Depocenter migrated from the north to the south in the late Meso- to Neoproterozoic. • Detrital zircon ages in the Mesoproterozoic and Paleozoic show variable provenances. • The North China Craton was involved in the assembly of the Rodinia Supercontinent. The North China Craton (NCC) is thought to experience multi-stage extensional events after the breakup of the Columbia (Nuna) Supercontinent, and even during the assembly of the Rodinia Supercontinent. In recent years, volcanic and detrital zircon U-Pb dating ages provided new insights into the Mesoproterozoic to Neoproterozoic tectonic framework in the NCC. As the Mesoproterozoic Xiong'er Group in the southern NCC is regarded as the oldest volcanic-sedimentary succession after the final amalgamation of the NCC, we reviewed the sedimentary environments and provenances of Mesoproterozoic to Neoproterozoic sedimentary sequences above the strata in order to understand tectono-sedimentary evolution of the southern NCC during this period. The early Mesoproterozoic sedimentary rocks were deposited in alluvial-fan to fluvial and (fan-) delta-coastal environments suggesting an initial stage of basin development. Fine-grained clastic sedimentary rocks interlayered with carbonate deposition formed on the southern NCC later, and implied a broad subsidence before ca. 1611 Ma. After that, depositional breaks caused by regional tectonic uplifts led to different sedimentary sequences and lateral migration of the depocenter from the north to the south (to the current co-ordinates). The unconformably overlying sedimentary rocks in the north of the southern NCC were deposited in restricted marine basins during late Mesoproterozoic to Neoproterozoic as a whole. However, the enlargement of shallow-marine shelf led to the thick accumulation of carbonates in the southernmost NCC characterized by a deepening-upward trend from the late Mesoproterozoic sequence. The Neoproterozoic sedimentary sequence is typified by sharp increasing terrigenous supplies and frequent changes in environment, and could be deposited in a tectonically active basin in consideration of its close association with volcanism. Detrital zircon grains from the oldest clastic sequence (i.e., the Bingmagou Formation) overlying the Xiong'er volcanic-sedimentary rocks and from the earliest Paleozoic sedimentary rocks (i.e., the Xinji Formation) are used to track changes of provenances. Detrital zircon grains from the Bingmagou Formation display two dominant age peaks at ca. 1850 and 2500 Ma and three secondary peaks at ca. 2100, 2350 and 2700 Ma. In contrast, detrital zircon grains from the Xinji Formation have three major age peaks at ca. 1850, 2200 and 2500 Ma and three subordinate populations of 950, 1100 and 1450 Ma. In combination with the uplifts during the Mesoproterozoic to Neoproterozoic, Neoproterozoic magmatism, and a large amount of detrital zircon derived from Rodinia-related orogenesis in the southern NCC, it is very likely that the major changes of basin configuration could be related to significant tectonic readjustment along with the evolution of the Rodinia Supercontinent. [ABSTRACT FROM AUTHOR]

• The accretionary complexes in the CAOB contain seamount fragments. • The pillow basalts in accretionary complexes show typical OIB affinity. • The stratigraphic framework of seamount was preliminarily reconstructed in Paleo-Asian Ocean. • A multiple intra-oceanic arc with seamount subduction and accretion model is proposed for the CAOB. The Central Asian Orogenic Belt (CAOB) is one of the largest and long-lived accretionary collages worldwide, and provides an ideal opportunity to address the fundamental geological processes and continental growth of accretionary orogens. However, the tectonic history of the CAOB is still controversial. Previous studies mainly focused on the process and model of accretion and subduction, but did not pay much attention to oceanic intraplate volcanoes. In this paper, we provide an overview of the salient features of twelve OIB-hosting accretionary complexes with ages from Late Neoproterozoic to Early Carboniferous in western the CAOB, and distinguish rock association of typical seamounts from accretionary complexes and shear zones, including pillow basalt, volcanic breccia, limestone, olistostromes and terrestrial clastic rocks. Combined with unique structural features of seamount, the stratigraphic framework of seamount was preliminarily reconstructed in Paleo-Asian Ocean, but the distribution and scale of seamounts is still not clear. Geochemically, volcanic rocks from seamounts are mainly alkaline basalts with litte tholeiitic basalts. The alkaline basalts are characterized by LREE enrichment and HREE depletion, and no obvious Nb, Ta and Ti negative anomalies, suggesting typical OIB affinity. The Nd, Sr and Pb isotopic features indicate that magma sources have enriched components and show fluid metasomatism. In short, this is consistent with geochemical features of Louisville, Ontong Java and Hawaiian seamounts which are related to mantle plumes, but do not contain high-Mg picrite and komatitic basalt. Based on our observations, and in combination with previous work, we present an innovative model in which the CAOB was involved multiple intra-oceanic arc with seamounts subduction and accretion, which is similar to the present-day Pacific and can better explain the tectonic evolution of the CAOB. However, further studies are needed to document the distribution, scale and mantle dynamics of seamounts in the CAOB. [ABSTRACT FROM AUTHOR]

A bi-material-matrix–double-inclusion concentration model is introduced into hybrid tight oil reservoir modeling. A modified rock physics template (RPT) of P-wave impedance versus Vp/Vs with three end members (sandstone, dolostone, and mudstone) is proposed to predict porosity and lithology of reservoirs. Seismic data inversion results coinciding with formation test results confirms the validity of the new RPT. • Experiments on tight oil samples reveal P-wave impedance and Vp/Vs changes. • Bi-material-matrix–double-inclusion concentration model tests parameter sensitivity. • P-wave impedance vs Vp/Vs used to predict reservoir porosity and lithology. Tight oil exploration and development in the Jimusar Sag of southeastern Junggar Basin of Northwest China has led to development of two reservoir segments in the Lucaogou Formation. The upper segment is mostly carbonate rocks, while the lower segment consists mainly of fine-grained clastic rocks. Both segments are mixed with clay, sand, and dolomite, which makes it difficult to identify the lithology and predict the porosity using a traditional seismic rock physics template (RPT). We analyzed the trends of ultrasonic P-wave impedance and Vp/Vs of laboratory data changing with lithology, porosity, and total organic carbon (TOC) content. Our data provide parametric sensitivity regarding porosity and TOC content by use of a bi-material-matrix–double-inclusion concentration model. We propose a modified RPT of P-wave impedance versus Vp/Vs with three end members (sandstone, dolostone, and mudstone) to predict porosity and lithology of reservoirs. We also present a new RPT of density versus Poisson ratio with the same three end members to predict TOC content and lithology of source rocks. These were validated by comparisons with laboratory measurements and log data. We inverted the porosity, TOC content, and thickness of the upper reservoir segment in the Lucaogou Formation of the J17 work area of Jimusar Sag by using the new RPT quantitative prediction method. The inversion results were identical to oil testing results, supporting the viability and effectiveness of the new RPTs. [ABSTRACT FROM AUTHOR]

• Clastic rocks of the South Tien Shan basement were deposited in the latest Neoproterozoic. • Neoproterozoic clastic rocks were sourced from the Karakum and Tarim continents. • Barrovian metamorphism in the Baisun block occurred at 352–340 Ma. • An archipelago model is proposed for metamorphic blocks of south Gissar. Paleozoic evolution of the western Tien Shan, which is built up on the basement of the Karakum continent, is poorly constrained compared to the better investigated Tien Shan terranes along the margin of the Tarim Craton. We present magmatic, metamorphic and detrital zircon ages for the regionally metamorphosed Baisun block and the metasediments comprising the Karakum basement in the westernmost parts of the South Tien Shan terrane. Age spectra of detrital zircon from metasediments of the Baisun metamorphic block and the western South Tien Shan show remarkable similarities over the vast area extending for ca. 500 km and are characterized by major Neoproterozoic peak at 1200–600 Ma and smaller peaks at 2300–1700 and 2700–2400 Ma. The 570–540 Ma ages of the youngest grains define late Neoproterozoic (Ediacaran) – early Cambrian maximum depositional ages of the metasediments. Comparison of the obtained age spectra with those published for the adjacent Tien Shan terranes indicate that the detrital zircon grains in the studied Ediacaran sediments were derived from the southern Precambrian continents of Karakum and Tarim while transport from the Northern Tien Shan was limited. The age of the Barrovian metamorphism in the Baisun block is constrained by ages of anatectic granites in the range 352–340 Ma, corresponding to early Carboniferous. These ages well match the 340–330 Ma ages, established for the adjacent Lolabulak and Garm metamorphic blocks. Based on the regional distribution of suture zones we suggest that during the Carboniferous the relatively small tectonic blocks of the South Gissar comprised an archipelago, located between the larger continents of Karakum and Tarim and possibly connected with the Paleotethys Ocean. The archipelago scenario can explain hot and rapid metamorphic and tectonic processes, documented in the South Gissar, similar to the ongoing collision along the Australia – SE Asia junction. [ABSTRACT FROM AUTHOR]

Graphical abstract Highlights • The newly recognized strata in the Gaerqin area (Gaerqin Formation) formed in the Norian Stage of the Late Triassic. • The Gaerqin Formation is the first reported Late Triassic Norian strata in the Duolong ore concentrating area of Tibet. • The Bangong Co–Nujiang Tethys Ocean was already a bathyal basin before the Late Triassic. Abstract We present the results of field mapping, paleontology, and detrital zircon geochronology of newly found clastic rocks with intercalations of limestone in the Gaerqin area of Tibet (Gaerqin Formation). The Gaerqin Formation consists of sandstone, siltstone, and shale with intercalations of bioclastic limestone. Abundant Late Triassic (Norian) fossils are found in the limestone beds. The fossils include Distichophyllia norica , Retiophyllia litangensis , and Mesozoic Chaetetida. In addition, 273 detrital zircons were selected for U–Pb dating, yielding the following age groups: 210–300, 500–600, 800–1100, 1600–1800, and 2400–2600 Ma. More than 80% of the detrital zircons are older than ∼550 Ma, and the most reliable youngest detrital zircon age for the Gaerqin Formation is ∼219 Ma. The results indicate that the Gaerqin Formation formed in a shallow marine to bathyal continental slope environment, and represents the first reported Upper Triassic (Norian) strata in the Gaerqin area of Tibet. The findings also suggest that the Bangong Co–Nujiang Tethys Ocean was a bathyal basin by the Late Triassic. [ABSTRACT FROM AUTHOR]

[Display omitted] • Sedimentary provenances in the North Yellow Sea Basin changed in the Middle Jurassic – Early Cretaceous. • The change of sedimentary provenance was associated with the transition from compressive to extensional tectonic setting. • The transformation of tectonic regime was completed in the Early Cretaceous. During the Mesozoic, the Eastern North China Craton experienced a transformation from the compressive to extensional tectonic setting. The Middle Jurassic-Lower Cretaceous sedimentary rocks of the North Yellow Sea Basin in the Eastern North China Craton may contain information about possible changes of sources of sediments. Based on the detrital zircon U-Pb ages of sedimentary rocks and the statistics of detritus of clastic rocks, this paper deal with the provenances of these rocks from the Middle Jurassic-Early Cretaceous in the North Yellow Sea Basin. The Middle Jurassic detritus of clastic rocks were from the basement of the basin and the Sulu Orogenic Belt in the Jiaodong Peninsula. In the Late Jurassic, the detrital particles from the Jiaobei Uplift and Sulu Orogenic Belt increased, and the detritus of clastic rocks from the Liaodong Peninsula also flowed into the basin. In the Early Cretaceous, the detritus of clastic rocks from the Jiaodong Peninsula decreased, while detritus of clastic rocks from the Liaodong Peninsula dominated. The provenances of the Middle-Upper Jurassic sedimentary rocks in the basin were controlled by multiple directions, while the provenance of the Lower Cretaceous sedimentary rocks changed from multiple directions to single direction. Obviously, with the passage of time (from Middle Jurassic to Early Cretaceous), the spatial transformation of the provenances in the North Yellow Sea Basin was a response to the transformation of regional tectonic setting. In the Early Cretaceous, the Eastern North China Craton completed transformation from the Paleo-Asian tectonic domain to the marginal Pacific tectonic domain. [ABSTRACT FROM AUTHOR]

[Display omitted] • The Early Carboniferous clastic sediments in the North Lhasa Terrane was mainly from the Indian continent and partly from the Australian continent. • The North Lhasa Terrane may be located at the northern margin of the Indian- and Australian continent during the Early Carboniferous. • The reduction of Grenvillian detrital zircons in the Yongzhu Formation might be associated with the Early Carboniferous rifting process in the eastern Lhasa Block. The Lhasa Block was located at the northern margin of East Gondwana before it drifted away, but its exact paleogeographic location in the Late Paleozoic remains controversial. The Late Paleozoic strata in the Lhasa Block, especially the Lower Carboniferous, for which the rock assemblage and sedimentary age have been described but the in-depth research on provenance and tectonic environment are still lacking, may provide vital information about its paleogeographic location. This study presents a systematic field geological survey of the Lower Carboniferous Yongzhu Formation, along with U-Pb dating and Hf isotope analysis of detrital zircons. The detrital zircons U-Pb data revealed major age peaks at 530 and 980 Ma as well as several subordinate age peaks at 784, 890, 1160, 1514, 1690, 2480, and 2600 Ma. The Hf isotopes of the detrital zircons showed similarity with zircons from the Indian continent on the age peaks at 980 and 890 Ma and with those from the Australian continent on the age peaks at 1160 and 2600 Ma, which indicates mixed provenance for the Yongzhu Formation. From this study, we infer that the Lhasa Block might have been located at the northern margin of the Indian and Australian continents during the Early Carboniferous. The weaker age peak at 1160 Ma of the Lower Carboniferous compared to the Pre-Carboniferous and Upper Carboniferous-Lower Permian might be related to the opening of the Sumdo Paleo-Tethys Ocean. [ABSTRACT FROM AUTHOR]

[Display omitted] • The clastic rocks in the Kuanping Group were deposited in the early Paleozoic (ca. 529–507 Ma). • These clastic rocks mainly originated from early Neoproterozoic granitoids in the Qinling Group. • The clastic rocks were likely deposited in a passive continental margin. • The North Qinling Orogenic Belt was located adjacent to the Indian Block on the margin of a Grenvillian orogen. The Kuanping Group is located in the northernmost North Qinling Orogenic Belt (NQB). The provenance and depositional age of clastic rocks from the Kuanping Group are pivotal for reconstructing the tectonic evolution of the NQB and the entire Qinling Orogenic Belt in Central China. The clastic rocks in the Kuanping Group have high CIA (66–73) and PIA (72–87) values similar to those of the post-Archean Australian shale (PAAS), implying the source materials experienced moderate to strong weathering. They have low values of ferromagnesian (e.g. Cr, Co, and Ni) and high field strength elements (e.g. Zr, Hf, Nb, Ta, and Y), indicating that they sourced from materials in an active continental margin. Detrital zircons from four samples of the clastic rocks have similar age spectra, which were dominated by early Neoproterozoic zircons (900–1000 Ma) with four subordinate populations (2400–2600 Ma, 1100–1300 Ma, 700–850 Ma). The main provenance of these clastic rocks was most likely the early Neoproterozoic granitoids that intruded in the oldest basement rocks (namely the Qinling Group) of the NQB, suggesting that the NQB has no tectonic affinity to the Yangtze and North China cratons during this period. Based on the youngest detrital zircons, the deposition age of the clastic rocks in the Kuanping Group is confined to the early Paleozoic (ca. 529–507 Ma). Based on the age distribution of detrital zircons and coeval rock assemblages, we suggest that the clastic rocks were likely deposited in a passive continental margin setting, which corresponds to the breakup of the Rodinia supercontinent. [ABSTRACT FROM AUTHOR]

[Display omitted] • Late Neoproterozoic ophiolite fragments were discovered in the Irshi area. • The early Paleozoic crust of the middle Great Xing'an Range is an orogenic belt. • Neoproterozoic–early Paleozoic lateral crustal growth occurred in the eastern CAOB. The tectonic affinity of the middle segment of the Great Xing'an Range (GXR) in NE China has become one of the focus issues about the Paleozoic crustal division and tectonic evolution of the eastern segment of the Central Asian Orogenic Belt. In this paper, we identified some ophiolite fragments from the early Paleozoic strata in the Irshi area of the middle segment of the GXR, which was previously thought to be the interior of the Precambrian Xing'an block. These ophiolite fragments and the surrounding deformed clastic rocks together constitute the Irshi ophiolite mélange (IOM). Zircon U-Pb dating reveals that the ophiolites formed during 603–608 Ma, which indicates that there was an oceanic basin during the late Neoproterozoic. The geochemical composition suggests that the ophiolites were formed in a back-arc setting. The youngest group of detrital zircons in the matrix ranges from 435 Ma to 480 Ma. In addition, the IOM was covered unconformably by late Silurian and Devonian strata, and it was thus likely emplaced during the early–middle Silurian. The identification of the IOM eliminated the possibility that the middle segment of the GXR was an independent Precambrian continental block. The spatial–temporal distribution of Proterozoic–early Paleozoic ophiolite, metamorphic complexes, and magmatic and sedimentary rocks in the middle segments of the GXR indicates that the tectonic affinity of the late Neoproterozoic–early Paleozoic crust in this area is an accretionary orogenic belt. The continuous subduction of the Paleo-Asian Ocean was responsible for the formation of the orogenic belt. [ABSTRACT FROM AUTHOR]

• Established a link between sedimentary cyclicity and the physico-mechanical properties of limestone and marl rocks. • Quartz has a significant impact on the mechanical characteristics and rock strength of the Dam Formation. • outlines the physico-mechanical characteristics of the marl-dominated emergence cycles and the limestone-dominated submergence cycles. • Development of workflow and empirical equations for use in subsurface reservoir modeling. This study aims to link the cyclicity with the mechanical and physical properties of limestone and marl rocks, using the Dam Formation in eastern Saudi Arabia as a case study. In this work, the Dam Formation sediments from five outcrop sections are investigated using detailed petrography, scanning electron microscope, X-ray diffraction, and petrographic image analysis software tool. Additionally, the physical and mechanical properties have been determined for marl and limestone samples. The study revealed that the emergence cycles result in the deposition of clastic sediments, in contrast to the submergence cycle, which leads to the deposition of carbonates. The dominant pore types, such as intercrystalline, micropores, mouldic, and vuggy, play an important role in the variation of mechanical and physical properties of the Dam Formation carbonate rocks. Secondary porosity produced by the dissolution of carbonate grains has a direct influence on mechanical properties. Physical measurements exhibit that limestone has a porosity of 10.5% and marl has a porosity of 5%. Regarding physical properties prediction, our analysis shows that the emergence cycle commonly increases the chances of a decrease in matrix porosity and an increase in fractures, vugs, and cavern porosity, as well as increasing the permeability of the carbonate in the Dam Formation. A combined analysis of sedimentological and diagenetic features indicates that the clastic or marly sequences have low porosity and high uniaxial compressive strength (UCS); conversely, the limestone rock has high porosity and low UCS values. Quartz has an impact on the mechanical properties of the Dam Formation and is a major control of rock strength in clastic sediments. The UCS in emergence cycles shows moderate to strong strength, and saturation results in a loss of strength. The loss of strength in water-saturated conditions during emergence cycles ranged from 8.54 % to 23.91 %, with a mean value of 13.39 %. The values from submergence formation reveal a 9.72–36.84 % decline, when the results of UCS of samples in dry settings are compared to all wet conditions. Various relationships and empirical equations linking and estimating the physical and mechanical properties of the emergence and submergence sedimentary cycles have been developed, which can assist in subsurface reservoir modeling in the absence of core measurements. The derived relationships and empirical equations can also be utilized as analogues for other marl-limestone successions in similar geological settings. [ABSTRACT FROM AUTHOR]

A submarine mud volcano (MV) known as TY1 is one of the largest conical structures found offshore southwestern Taiwan. Active gas bubble emissions at the flat crest of the mud volcano disperse sediment particles into the water column. Changes in the mud volcanism of TY1 were revealed by radiograph and grain size analysis of the sediment cores. 210 Pb geochronology was applied to the near-seafloor sediments to reveal the detailed mud volcanism from the deposition rate. In a 58-cm long sediment core taken from the northern margin of the crest, known as TY1-N.170, the size and frequency of the mud clasts decrease upward. The clasts are smaller than 8 mm above a sediment depth of 34 cm below the sea floor (cmbsf). Sediments between 0 and 19 cmbsf are massive, and particles larger than 2 mm are absent. An enrichment of coarse, silt-sized particles in the massive sediment unit and the restricted distribution of the unit suggest that the massive unit was generated by re-deposition of sediment particles that were dispersed into the water column by gas bubble emission. These characteristics suggest that during the last mud volcanism of TY1, there was a decrease in mud eruption energy, and gas bubble emission became the main activity. In core TY1-S.440, taken from the southern slope, a massive sediment unit enriched with coarse, silt-sized particles, is intercalated between mud breccia structures. This suggests repeated mud breccia flows caused by TY1. The excess 210 Pb activity present in the massive sediment unit of TY1-N.170 suggests activation of gas bubble emission. In the massive unit, a decrease in excess 210 Pb activity appears upward toward the seafloor. The highest value is 3.1 dpm/g at 19.8 cmbsf (26.4 g/cm 2 in cumulative mass); values lower than 1.0 dpm/g are distributed 2.8–6.8 cmbsf (3.6–8.8 g/cm 2 ). The upwardly decreasing trend is opposite that of the reference core from which a reasonable areal sedimentation rate was obtained using a constant-flux constant-sedimentation model. The anomalous depth profile at the massive unit indicates an increasing rate of sediment deposition, which originated from the activation of gas bubble emission. [ABSTRACT FROM AUTHOR]

The Bangong-Nujiang suture zone, separating the Lhasa and Qiangtang blocks of the Tibetan Plateau, is marked by remnants of the Bangong-Nujiang oceanic basin. In the Gaize area of central Tibet, Mesozoic sedimentary strata recording the evolution of the basin and subsequent collision between these two blocks include the Upper Triassic-Lower Jurassic turbidites of the Mugagangri Group, the Upper Jurassic-Lower Cretaceous sandstone-dominated Wuga and Shamuluo formations, and the Upper Cretaceous molasse deposits of the Jingzhushan Formation. The Shamuluo and Jingzhushan formations rest unconformably on the underlying Mugagangri Group and Wuga Formation, respectively. In this contribution, we analyze petrographic components of sandstones and U-Pb-Hf isotopic compositions of detrital zircons from the Wuga and Jingzhushan formations for the first time. Based on the youngest detrital zircon ages, the maximum depositional ages of the Wuga and Jingzhushan formations are suggested to be ∼147–150 Ma and ∼79–91 Ma, respectively. Petrographic and isotopic results indicate that sediments in the Wuga Formation were mainly sourced from the accretionary complex (preserved as the Mugagangri Group) in the north, while sediments in the Jingzhushan Formation have mixed sources from the Lhasa block, the Qiangtang block and the intervening suture zone. Provenance analysis, together with regional data, suggests that the Upper Jurassic-Lower Cretaceous Wuga and Shamuluo formations were deposited in a peripheral foreland basin and a residual-sea basin, respectively, in response to the Lhasa-Qiangtang collision, whereas the Upper Cretaceous Jingzhushan Formation reflects continental molasse deposition during the post-collisional stage. The development of the peripheral foreland basin evidenced by deposition of the Wuga Formation reveals that the age of the initial Lhasa-Qiangtang collision might be the latest Jurassic (∼150 Ma). [ABSTRACT FROM AUTHOR]

Late Paleocene sedimentation in the pericratonic Kachchh Basin marks the initial marine transgression during the Cenozoic era. A 17 m thick sandstone-dominated succession, known as the clastic member (CM) of the Matanomadh Formation (MF), is exposed sporadically in the basin. Three facies associations are reconstructed in the succession in three different sections. Facies association-1 contains matrix-supported pebbly conglomerate facies, horizontally-laminated sandstone-mudstone alternation facies, hummocky- and swaley cross-bedded sandstone facies, wave-rippled sandstone facies and climbing ripple cross-laminated sandstone facies. This facies association developed between shoreface and foreshore zone under the influence of storms on a barrier ridge. Facies association-2 contains sigmoidal cross-bedded sandstone facies, sandstone-mudstone alternation facies, flaser-bedded sandstone facies, herringbone cross-bedded sandstone facies and tangential cross-bedded sandstone facies. This facies association possessing tidal bundles and herringbone cross-beds developed on a tidal flat with strong tidal influence. Facies association-3 comprises pebbly sandstone facies, horizontally-bedded sandstone facies, tangential cross-bedded sandstone facies exhibiting reactivation surfaces and tabular cross-bedded sandstone facies. This facies association represents sedimentation in a river-dominated estuary and reactivation surfaces and herringbone cross-beds indicating tidal influence. The bipolar paleocurrent pattern changes to unipolar up-section because of the change in the depositional currents from tidal to fluvial. The sedimentation took place in an open coast similar to the Korean coast. The presence of neap-spring tidal rhythmites further suggests that a semidiurnal system similar to the modern day Indian Ocean was responsible for the sedimentation. Here, the overall sequence developed during the transgressive phase where barrier ridge succession is succeeded by the tidal flat succession and the latter, in turn, is succeeded by the estuarine succession. This study resolves the most debated issue of initial marine transgression in the Kachchh Basin during the Cenozoic. [ABSTRACT FROM AUTHOR]

• Early Silurian clastic rocks were deposited in a passive margin setting. • Sediments were sourced from the interior of the SCB and the Northern East Gondwana. • Xuefeng Uplift underwent rapid uplift and erosion during the Early Silurian. • Xuefeng Uplift was an intraplate basement uplift affected by the Kwangsian Orogeny. Xuefeng Uplift is located on the southeast Upper Yangtze region, west of the Cathaysia. Clastic rocks in the Early Silurian Xiaoheba Formation were deposited on northwest flank of the Xuefeng Uplift. Provenance of these clastic rocks may record the Early Silurian tectonic evolution of the Xuefeng Uplift. In this paper, we present whole-rock geochemical data and detrital zircon U–Pb ages for the Xiaoheba Formation. Geochemical signatures suggest that the Early Silurian clastic rocks were deposited in a passive margin and mainly derived from felsic igneous rocks and recycled sedimentary rocks. Two major age populations of 1000–900 Ma and 900–700 Ma, as well as four minor populations, were identified. Our data suggest that the Cathaysia, especially the Wuyi–Yunkai domains, experienced intensive uplift in the Early Silurian, resulting in numerous recycled detritus (1000–900 Ma) supplied to the study area crossed through the Xuefeng Uplift. Meanwhile, age population of 900–700 Ma suggests that the Xuefeng Uplift was an additional source for the Xiaoheba Formation, indicating the uplift had already formed in the Early Silurian. Based on aforementioned evidence and published data, we consider that the formation of Xuefeng Uplift is associated with the Early Paleozoic intraplate orogenesis. The Xuefeng Uplift may have partly uplifted above sea level in this period, but it did not obstruct sediments derived from the Cathaysia. The youngest age cluster of zircons is 436 ± 5.7 Ma, indicating the maximum deposition age of the Xiaoheba Formation and implying the initial formation time of the uplift is roughly in the Early Telychian. [ABSTRACT FROM AUTHOR]

[Display omitted] • Detrital zircons indicate derivation from the Variscan rocks. • Continental ribbon was separated from the northern margin of Gondwana. • Back-arc passive margin evolved into a lacustrine basin. The processes that caused removal of the upper Carboniferous to Permian sediments in the eastern Sakarya Zone, Turkey, are modeled by using of geochemical data and LA-ICP-MS U–Pb ages from detrital zircons. A felsic provenance and passive margin setting during the deposition of the upper Carboniferous Çatalçeşme sediments are inferred from the geochemistry of sandstones (SiO 2 > 85 wt%). Chemical Index of Alteration (CIA) values (75 – 81) indicate warm and humid climatic conditions and tectonic tranquility during deposition. Fifty-three (58%) concordant zircon grains produce a youngest age population in the range of 308.7 ± 4.4 to 342.1 ± 6.9 Ma, typical for the Variscan events. The burgundy color and upward-fining in clast size and bed thickness are the most prominent features of the concordantly overlying Hardişi Formation. Geochemistry (SiO 2 = 66–81 wt%) and CIA values (58–65) of the clastic rocks point to a subduction-related tectonic setting and increasing rate of erosion in the source area. We highlight that the Çatalçeşme sediments were deposited in a back-arc basin opened to the south of a continental ribbon separated from Gondwana. Approaching of the Paleotethyan mid-ocean ridge to the subduction zone was resulted in flattening in subducting slab, which in turn caused the back-arc basin to migrate into the interior parts of Gondwana and the former back-arc basin to evolve into a lacustrine setting. Increase in the elevation of source areas was resulted in an increase in the rate of physical erosion and transportation of burgundy Hardişi clastic sediments into the lacustrine basin. [ABSTRACT FROM AUTHOR]

[Display omitted] • (La/Yb) N -Na 2 O/Al 2 O 3 plot can be used to identify analcime-bearing pyroclastic rocks. • Th/U-Rb/Sr plot may identify pyroclastic rocks deposited in reducing conditions. • Pyroclastic rocks in Lunpola Basin originated from ultrapotassic and adakitic magmas. • The west Lhasa terrane was dominated by mantle lithosphere detachment. • The east Lhasa terrane was characterized by lower crustal thickening. Tephrochronology provides a powerful tool to date and correlate the sedimentary sequence. However, the recognition of tuff and tuffinite in Cenozoic sequences is challengeable because of modification and alteration during diagenesis. In this contribution, we studied samples from the Cenozoic Lunpola basin on the central Tibetan Plateau to explore the potential provenance and distinction of pyroclastic materials from clastic sediments and to recognize the source-to-sink process of pyroclastic rocks and their deep geodynamic implications. The bulk mineralogical compositions and major and trace elements and Sr-Nd-Hf isotopic compositions of the pyroclastic rocks and clastic sediments in the Lunpola Basin were determined and compared with those of contemporary volcanic rocks in the Lhasa terrane. It is suggested that Th/U-Rb/Sr and (La/Yb) N -Na 2 O/Al 2 O 3 discrimination plots might be used to distinguish pyroclastic from clastic sedimentary rocks in terms of source, transportation and diagenesis. According to the trace element and Sr-Nd and Hf isotope signatures, the 23.5 Ma pyroclastic rocks in the Lunpola Basin may originate from the Xungba ultrapotassic magmatism, and the ∼ 21- ∼15 Ma pyroclastic rocks may have been supplied by corresponding adakitic magmatism. The spatial distributions of the ultrapotassic and potassic as well as adakitic volcanic rocks in the Lhasa terrane may reveal that the west Lhasa terrane mantle lithosphere was detached and the east Lhasa terrane lower crust was thickened along with the India-Asia plate convergence. [ABSTRACT FROM AUTHOR]

The Mesozoic Shanghang Basin in southeastern China consists of Early Cretaceous mottled coarse-grained clastic and volcanic rocks, and Late Cretaceous clastic rocks. The volcanic rocks are intermediate-mafic to felsic and spatially close to the famous Zijinshan Mineral Field. In order to better understand the timing, petrogenesis and tectonic setting of these volcanic rocks and the relationship between magmatism and metallogeny in the mineral field, U–Pb zircon geochronological, geochemical and Sr–Nd–Pb–Hf isotopic studies were completed on the volcanic rocks. Fifteen LA-MC-ICP-MS U–Pb zircon analyses of the volcanic rocks yield weighted mean ages of between 105 and 99 Ma. Major and trace element geochemistry shows that these rocks are mostly high-K to shoshonitic, enriched in LREE and Th, U, and depleted in Ba, Nb, Sr, P and Ti. The volcanic rocks have 87 Sr/ 86 Sr i ratios of between 0.70732 and 0.70977, 206 Pb/ 204 Pb isotope ratios of 18.57–19.77, 207 Pb/ 204 Pb isotope ratios of 15.64–15.71, 208 Pb/ 204 Pb isotope ratios of 38.87–40.62, 176 Hf/ 177 Hf ratios of 0.282589–0.282823, ε Nd T values of −7.5 to −4.7, and ε Hf( t ) values of −4.2 to 4. Such characteristics, with similarities to coeval volcanic and intrusive rocks adjacent to the basin, suggest that the parent magma of the Cretaceous volcanic rocks in the basin and their contemporaneous intrusives originated from crustal melts with a juvenile component. Petrogenetically, fractional crystallization with minor wall-rock assimilation is the controlling process in deriving a wide range of more evolved rocks. With reference to the ore-forming events and isotopic features of ore-related intrusions in the Zijinshan Mineral Field, we propose that volcanism in the Shanghang Basin and coeval magmatism in the mineral field are related to the formation of the regional porphyry and epithermal Cu–Au–Mo–Ag deposits in an extension tectonic setting related to the subduction of the Paleo-Pacific Plate. [ABSTRACT FROM AUTHOR]

The Zambales Ophiolite Complex in Luzon, Philippines is made up of two blocks with differing geochemical signatures and ages – the Middle Jurassic to Early Cretaceous Acoje Block-San Antonio Massif that is of island arc tholeiite composition and the Eocene Coto Block-Cabangan Massif which is of transitional mid-ocean ridge basalt-island arc tholeiite affinity. These ophiolitic bodies are overlain by Miocene to Pliocene sedimentary units whose petrochemistry are reported here for the first time. Varying degrees of influences from ophiolitic detritus and from arc volcanic materials, as shown by petrography and indicator elements including Cr, Co and Ni, are observed in these sedimentary formations from north to south and from the oldest to the youngest. The Early to Middle Miocene Cabaluan Formation, whose outcrops are found to overlie only the Acoje Block, registers a more dominant ophiolitic signature as compared to the Late Miocene to Pliocene Santa Cruz Formation. The Santa Cruz Formation is generally characterized by fewer ophiolitic clasts and higher amounts of felsic components. Additionally, within this formation itself, a pronounced compositional change is observed relative to its spatial distribution. From the south to the north, an increase in ophiolitic components and a relative decrease in felsic signature is noted in units of the Santa Cruz Formation. It is therefore inferred that changes in the petrochemistry of rocks from the older Cabaluan to the younger Santa Cruz sedimentary formations record a decline in the influx of ophiolitic detritus or, conversely, the introduction of more diverse sediment sources as the deposition progressed. Detrital zircon U–Pb ages from the Santa Cruz Formation, with peaks at 46.73 ± 0.94 and 5.78 ± 0.13 Ma, reflects this change in provenance from the unroofing of an Early Eocene oceanic crust to fresh contributions from an active volcanic arc during the Late Miocene. The contrast in compositions of the southern and northern Santa Cruz Formation also indicates a closer proximity of the southern units to the source of these non-ophiolitic sources, which most likely corresponds to the Pliocene volcanoes of the West Luzon Arc. [ABSTRACT FROM AUTHOR]

[Display omitted] • Grenville-age terrane is identified in the Qilian orogen. • The Precambrian basement of the Qilian orogen is divided into four distinct mega-sequences. • ∼475 Ma metamorphism was related to the subduction of the Proto-Tethys Ocean. The Qilian orogen at the northeastern margin of the Tibetan Plateau records a complete history from continental breakup to oceanic basin evolution and back to continental collision during the Neoproterozoic to Paleozoic interval. The Qilian Ocean, as a branch of the Proto-Tethys Ocean, was connected to the Iapetus Ocean but is lesser known than its two more famous counterparts. This paper presents zircon U-Pb and biotite-muscovite 40Ar/39Ar isotope data from the Yemananshan Complex in the western Central Qilian belt to assess the age and provenance of late Mesoproterozoic-early Paleozoic successions in the Qilian orogen. The results indicate the Central Qilian belt is characterized by Late Mesoproterozoic-early Neoproterozoic orogenesis with magmatism from 1200 Ma to 900 Ma and clastic metasedimentary rocks deposited between 1050 and 920 Ma. Statistical analysis of detrital zircon data and auxiliary temporal information from the Qilian orogen affirms the notion that sedimentation occurred in four distinct megasequences: (1) 1950–1850 Ma, the oldest known strata, (2) 1250–920 Ma, during Grenvillian-Sveconorwegian orogenesis, (3) 840–760 Ma, the disintegration of Rodinia, and (4) 650–550 Ma, which is typical of the orogenic belts that sutured the Gondwana continental blocks. Metamorphic zircon and 40Ar/39Ar isotope data indicate early Paleozoic metamorphism at ca. 475 Ma, which overlaps with magmatic activity associated with arc-back-arc basin development in the Central Qilian belt, which was associated with subduction of the Proto-Tethys in eastern Gondwana. [ABSTRACT FROM AUTHOR]

Highlights: [•] Detrital zircon of mid-Jurassic AC sandstone in SW Japan was dated by LA-ICPMS. [•] Most of zircon grains range in the Jurassic, Permo-Triassic, and middle Paleozoic. [•] Older grains of Paleoproterozoic and Neoarchean ages were likely from N. and S. China. [•] Mid-Jurassic trench in SW Japan developed along the Cathaysia margin of S. China. [ABSTRACT FROM AUTHOR]

[Display omitted] • The Longmuco-Shuanghu-Lancangjiang suture zone represents an in situ relic of the Paleo-Tethys Ocean. • The northward subduction of the Paleo-Tethys oceanic lithosphere was continuous at least during the Late Devonian to Triassic. • The collision between the North and South Qiangtang subterranes began at ∼ 225 Ma. The Qiangtang terrane, which is divided into the North and South Qiangtang subterranes, is a key unit to study the evolution of the Paleo-Tethys Ocean in the Tibetan Plateau. Here we present new detrital zircon U-Pb and Lu-Hf isotopic data from a Paleozoic-Triassic sedimentary succession in the Qiangtang terrane. This new dataset is used to unravel the tectonic affinity of the North and South Qiangtang subterranes and the evolution of the Paleo-Tethys Ocean. Detrital zircons from the Paleozoic-Triassic sedimentary succession in the North Qiangtang subterrane are generally poorly rounded, indicating short transported distance. They yielded variable U-Pb ages ranging from 3399 Ma to 233 Ma with major age peaks of 358 Ma and 266–248 Ma, and ε Hf (t) values of −18.6 to 19.3. These features reveal that these detrital zircons were most likely derived from arc magmatic rocks, which were associated with the subduction of the Paleo-Tethys oceanic lithosphere. By contrast, detrital zircons from the Paleozoic sedimentary succession in the South Qiangtang subterrane are characterized by sphericity and ellipsoid, with most Th/U values > 0.1. They yielded U-Pb ages of 3624–321 Ma and three consistent age peaks of 549–527 Ma, 973–940 Ma and 2504–2470 Ma. They display ε Hf (t) values ranging from –33.4 to 26.2, with a cluster of −20.0 to 10.0. These features are similar to those of the detrital zircon grains from the South Qiangtang, Lhasa, and Himalaya terranes, as well as the Indian Gondwana. Detrital zircon ages data suggest that the North and South Qiangtang subterranes were derived from the Yangtze block and Gondwana, respectively. Available data indicate that the northward subduction of the Paleo-Tethys oceanic lithosphere was continuous at least during the Late Devonian to Triassic. The collision between the North and South Qiangtang subterranes was initiated at ∼ 225 Ma. [ABSTRACT FROM AUTHOR]

[Display omitted] • The sedimentary provenance is different across the Char Shear Zone in eastern Kazakhstan. • The Char Shear Zone represents the suture between the Siberian margin and the Kazakhstan collage in eastern Kazakhstan. • The oceanic basin between the Siberian margin and the Kazakhstan collage was closed after 321 Ma. To unravel when, where, and how multiple arc systems were amalgamated is crucial for understanding the accretion processes of the Central Asian Orogenic Belt. Here we focus on the collision of the Siberian margin and the Kazakhstan collage along the Char Shear/Suture Zone in eastern Kazakhstan. We conducted U–Pb dating and Hf isotope analysis for detrital zircons of clastic rocks across the collisional zone of the Siberian margin (the Irtysh-Zaisan Complex) and the Kazakhstan collage (the Zharma-Saur Arc and the Char Zone). Our results show that the Irtysh-Zaisan Complex carries abundant early Paleozoic detrital zircons and minor Precambrian zircons, but there is a lack of such zircon populations in the Zharma-Saur Arc and the Char Zone. Devonian to Carboniferous detrital zircons appear in all sampling tectonic units, in which ε Hf (t) values of Carboniferous zircons from the Zharma-Saur Arc and the Char Zone are characterized by a narrow range (∼10–17) that is different from a relatively wider range of ε Hf (t) values of ∼5–18 for the Carboniferous zircons in the Irtysh-Zaisan Complex. The distinct sedimentary provenances of the Irtysh-Zaisan Complex and the Zharma-Saur Arc/Char Zone confirm that their tectonic boundary lies along the Char Shear Zone in eastern Kazakhstan. As the Late Carboniferous sedimentary rocks from the Zharma-Saur Arc and the Char Zone do not receive detritus from the Siberian margin, we consider that the Ob-Zaisan Ocean between the Siberian margin and the Kazakhstan collage was closed later than the deposition of these sedimentary rocks (<321 Ma). [ABSTRACT FROM AUTHOR]

[Display omitted] • Single-grain ZHe ages of the clastic rocks in Tarim Basin are dispersed with 94 Ma-995 Ma. • The forward and inverse modeling reveals four cooling events since the Neoproterozoic. • The samples experienced several thermal events with the highest temperature of 160–180 ℃. Thermal history reconstruction of the deep and ancient strata (Pre-Silurian) in the Tarim Basin is always difficult due to the lack of effective paleo-thermal indicators. This study provides a new strategy for thermal history reconstruction of the Tarim Basin with the zircon (U-Th)/He thermochronology. The obvious dispersion of the single-grain zircon (U-Th)/He ages for all the clastic rocks in the Tarim Basin reflects the complex and protracted thermal histories. The combination of forward and inverse modeling revealed that the Neoproterozoic rocks from the Kalpin and Bachu Uplifts experienced four rapid cooling events beginning in the Late Ordovician, Late Carboniferous, Late Triassic and Early Miocene, while the Silurian rocks in the eastern Tarim Basin just experienced the Late Carboniferous and Late Cretaceous cooling events. In addition, these rocks experienced several thermal events with the highest temperature of 160–180 °C (a precision of 5–10 °C). The unique thermal histories in the Tabei Uplift and Shunbei area was suitable for the crude oil preservation. This study not only promotes the application of the zircon (U-Th)/He thermochronology in sedimentary basins but also clarify the thermal evolution process of the ancient strata in the Tarim Basin, which plays an important role in determining the deeper source rocks maturation phase and hydrocarbon occurrence state. [ABSTRACT FROM AUTHOR]

Highlights: [•] Gorkhi Formation clastic rocks were sourced from plutonic rocks in continental margin and continental island arc. [•] The depositional age of the Gorkhi Formation is 340–320Ma. [•] Spatial and temporal changes in the provenance of the accretionary complex are proposed. [ABSTRACT FROM AUTHOR]

Abstract: Seismic attributes for the interpreting explorationist are numerous. Some are useful, some duplicative, and some less useful. However, with respect to optimizing a systematic basin analysis approach which relies upon heavily upon integrating seismic facies, there are eight particularly useful attributes which have clear geophysical meaning, strong underlying geological rock-fluid implications, and which for clastic depositional environments greatly assist in determining seismic facies, associated paleoenvironments, and lessening the number of interpretive possibilities. They are: Amplitude Envelope, Chaos, Cosine of Phase, Dip Deviation, Instantaneous Frequency, Q, Relative Acoustic Impedance, and Variance. A systematic application of these first order attributes for the East China Sea in particular, and for other clastic environments in general, allows a first pass assessment of a basin’s exploration potential through seismic reconnaissance, an interpretive reconnaissance whose accuracy is limited only by the seismic fidelity of the lines and logic of the assumed geology employed. [Copyright &y& Elsevier]

Abstract: Geochemical studies done on the Baguio Mineral District had dominantly looked at the igneous rocks. A major gap is the scarcity of studies dealing with the sedimentary rock geochemistry for this district which this paper intends to address. The petrographic data and major and trace element compositions of the siltstones–sandstones from the lower member of the Late Oligocene to Early Miocene Zigzag Formation show that they are generally quartz-rich and have high K2O, Th and La/Sc contents. The chondrite-normalized REE pattern exhibits a negative Eu anomaly, enrichment in LREEs and flat HREEs similar to typical post-Archean shales. Taken together, the data indicate derivation of the lower member of the Zigzag Formation from intermediate to acid igneous rock sources generated in an active margin setting. A likely candidate source is the Cordon Syenite Complex/Palali Formation in the Northern Sierra Madre – Caraballo Mountains. Derivation from mafic source rocks in an oceanic island arc setting is inferred for samples of the Middle to Late Miocene Klondyke, Late Miocene to Early Pliocene Amlang and Late Pliocene Cataguintingan Formations. These samples are characterized by low K2O, Th and La/Sc but high Cr/Th values. Unroofing of the Pugo Metavolcanics and the younger plutons in the Central Cordillera provided the materials which eventually produced the Klondyke and Amlang Formations. Continuous uplift and shallowing of the basin resulted in the deposition of the Cataguintingan Formation. The petrography, geochemistry and geological features of the sedimentary rocks clearly define the change in sediment provenance from quartz-rich during the Oligocene to quartz-deficit in the Miocene. This offers additional constraints in understanding the geological evolution of the mineral district. [Copyright &y& Elsevier]

Abstract: The Late Carboniferous palaeo-tectonic setting of the West Junggar region is comprised of arcs alternating with basins. Geochemical analysis of the sedimentary rocks associated with these arc-related basins was conducted to better constrain the provenance and tectonic setting. Major and trace element geochemistry data of Late Carboniferous mudstones and sandstones in the Hala-alat Mountains suggest that these sedimentary rocks and their source areas are characterized by the following four features: (1) sediments experienced a simple recycling process; (2) a low degree weathering conditions in the source areas; (3) compositional immature of the sedimentary rocks; (4) dominated by intermediate to felsic provenance, with a few intermediate to mafic sediments. Integrated with the palaeo-flow data and previous authors’ works, a fore-arc basin model is proposed for the tectonic setting of the sedimentary rocks. The Sawur arc is the primary provenance and supplies the major intermediate to felsic detrital fragments. The Bozchekul-Chingiz arc and Kexia oceanic island arc are the other two secondary sources. [Copyright &y& Elsevier]

Abstract: The Uneged Uul structure is a ∼10km circular, complex, multi-ridged domal feature in the Unegt subbasin of the East Gobi Basin, southeastern Mongolia. As revealed by remote sensing and recent field reconnaissance, the central part of the Uneged Uul structure comprises a complex central peak of outward-radiating curved ridges, composed of stratigraphically uplifted greenschist-facies basement schists, surrounded by an annular moat. The most prominent feature of the structure is a central annular ridge ∼3km in diameter composed of pebble-boulder conglomerates and gravels of the Upper Jurassic Sharilyn Formation, surrounded by three outer domal ridges composed of Lower Cretaceous conglomeratic sandstones and gypsum clays. Jurassic conglomerates forming the main part of the central annular ridge show effects of severe internal deformation. The original population of pebbles, cobbles and boulders appears moderately displaced and mostly broken but nowhere aligned along shear planes or foliated. Primary sedimentary features, such as cross-lamination or imbrication, have been obliterated. We explain this penetrative brecciation as a result of dissipative shearing caused by a strong and rapid singular event that in magnitude was beyond the range of the common crustal tectonics recorded elsewhere in this region. Disrupted and chaotically distributed conglomeratic sandstone beds in the central annular ridge dip in highly variable directions on a local scale but show an apparent SE-NW trend of bedding plane alignment. Further outside, the tilted and uplifted Upper Jurassic to Lower Cretaceous strata of the domal area are overlain by the flat-lying Upper Cretaceous, which stratigraphically constrains the timing of deformation at the Uneged Uul structure to most likely the Early Cretaceous. Endogenic formation models, such as magmatism and salt, gypsum, or mud diapirism, fail to explain the nature of the Uneged Uul structure. The Uneged Uul structure bears a set of geomorphic and structural features resembling those at some eroded complex impact structures on Earth. Morphologically similar central peaks are observed at the Spider and Matt Wilson impact structures in Australia; the central annular ridge reminds of that at Gosses Bluff in Australia; the outer domal ridges might correspond to ring-like features as known from Tin Bider in Algeria. We, therefore, cautiously propose that an impact may have produced the Uneged Uul feature causing structural uplift (∼1000m) of basement rocks at its center. So far, no convincing evidence for shock metamorphism could be proven by field work and petrographic analyses. However, it is likely that at the time of the deformation event the unconsolidated conglomerates were highly porous and possibly immersed in groundwater buffering the propagation of sudden stress-reducing deformation. Further studies will be in order to unravel the nature of the Uneged Uul structure, which should be considered a promising possible impact structure. [Copyright &y& Elsevier]

Abstract: The provenance, source rock compositions, and sediment supply system for a convergence zone of the Paleo-Tethys were reconstructed based on the petrography and geochemistry of clastic rocks of the Inthanon Zone, northern Thailand. The clastic rocks are classified into two types based on field and microscopic observations, the modal composition of sandstone, and mineral compositions: (1) lithic sandstone and shale within mélange in a Permo–Triassic accretionary complex; and (2) Carboniferous quartzose sandstone and mudstone within the Sibumasu Block. Geochemical data indicate that the clastic rocks of the mélange were derived from continental island arc and continental margin settings, which correspond to felsic volcanic rocks within the Sukhothai Zone and quartz-rich fragments within the Indochina Block, respectively. The results of a mixing model indicate the source rocks were approximately 35% volcanic rocks of the Sukhothai Zone and 65% craton sandstone and upper continental crust of the Indochina Block. In contrast, Carboniferous quartzose sedimentary rocks within the Sibumasu Block originated from a continental margin, without a contribution from volcanic rocks. In terms of Paleo-Tethys subduction, a continental island arc in the Sukhothai Zone evolved in tandem with Late Permian–Triassic forearc basins and volcanic activity during the Middle–early Late Triassic. The accretionary complex formed contemporaneously with the evolution of continental island arc during the Permo–Triassic, supplied with sediment from the Sukhothai Zone and the Indochina Block. [Copyright &y& Elsevier]

Abstract: A Permo-Triassic volcanic arc system, the Sukhothai Arc, is recognised between the Indochina and Sibumasu continental blocks. The Chanthaburi terrane is here interpreted as a fault-detached, highly disrupted southern segment of the Sukhothai Arc, occupying part of southeastern Thailand and extending into Cambodia. The Klaeng tectonic line is defined as the boundary between the Chanthaburi terrane and Sibumasu block. The stratigraphy of the Chanthaburi terrane is compared with that of the Sukhothai terrane in Northern Thailand. The Late Palaeozoic–Mesozoic sequences of these two volcanic arc terranes in the Sukhothai Zone share important similarities, but show marked contrasts to those of the Sibumasu and Indochina blocks, where the Late Permian–Triassic is largely absent due to the Indosinian I unconformity (western Indochina) or is dominantly carbonates with little terrigenous clastic input (Sibumasu). There is no clear evidence of pre-Carboniferous sedimentary rocks for either the Sukhothai or Chanthaburi terranes. Late Permian lyttoniid brachiopod shale near Klaeng in the Chanthaburi terrane was revisited. The brachiopod, previously reported as Leptodus, is re-identified to Oldhamina, the genus previously known, elsewhere in Southeast Asia, only in the Huai Tak Formation of the Sukhothai terrane. Oldhamina in Thailand is confined to the Sukhothai Arc. The marine stratigraphy of the Sukhothai Arc is represented by a Permian–Triassic lithological succession of mixed carbonates and siliciclastics, with common volcanic material. The Late Permian and Triassic litho- and biostratigraphy of the Chanthaburi terrane are comparable with the upper Ngao and Lampang groups of the Sukhothai terrane; in particular, they share similar successions from Oldhamina brachiopod bearing shale to Palaeofusulina–Colaniella foraminifer bearing limestone in the latest Permian. Marine depositional conditions were terminated on the Sukhothai Arc by end-Triassic times, later than on the Indochina block (Late Permian) but earlier than on the Sibumasu block (Jurassic/Cretaceous). [Copyright &y& Elsevier]

Abstract: A Late Cretaceous tempestite in the northern Songliao Basin, China, was studied based on thin-section and granularity analyses of borehole samples. The results indicated that the local tempestite can be categorized into several clastic constituent types, which include bottom erosion structures, graded beds, hummocky cross stratification (HCS), parallel beds, wave marks, and bioturbation structures. Based on these sedimentary characteristics and vertical sequence combinations, four tempestite sedimentary models were developed: (I) an autochthonous tempestite facies, (II) an allochthonous tempestite facies (the proximal subfacies), (III) a second allochthonous tempestite facies (the distal subfacies), and (IV) a turbidite facies. [Copyright &y& Elsevier]

[Display omitted] • The western Ordos Basin has excellent potential to form sandstone-type uranium deposits. • The search for uranium reservoirs should focus on the northwest of the Ordos Basin. • Regions where intermediate-acid rocks are present are ideal targets for uranium exploration. • Tracking along the provenance supply direction is an effective method for uranium exploration. The Middle Jurassic Zhiluo Formation is the main uranium-bearing sequence in the western Ordos Basin, northern China. Provenance studies of clastic rocks in the Zhiluo Formation are important to provide guidelines for uranium exploration. In this paper, we describe the sandstones from the Zhiluo Formation and report their bulk rock elemental compositions by using samples that were collected from the Lingwu area, western Ordos Basin. Our main objective is to provide constraints on the provenance of the sandstones and thus new insights into uranium exploration. The results show that the sources of the Zhiluo Formation sandstones have TTG (trondhjemite-tonalite-granodiorite) attributes and mainly consist of magmatic arc orogenic belts that were mixed with continental blocks and recycled orogenic belt materials. The paleocurrent measurements that average 144° suggest that the provenance supply direction of the sandstones is from northwest to southeast. Combined with the regional tectonic settings, it can be inferred that the sandstone provenance was mainly provided by the Xingmeng Orogenic Belt, while the Alxa Block and Helan Mountain complex rocks also contributed. Our research might provide a crucial reference for predicting the locations of potential uranium reservoirs, i.e., the search for uranium mineralization should target the northwest of the Ordos Basin, especially near regions where intermediate-acid rocks are present. This information is integrated into a predictive model in which tracking along the provenance supply directions of clastic sediments is an efficient method for conducting uranium exploration in a sedimentary basin. [ABSTRACT FROM AUTHOR]

[Display omitted] • The development of basins in the Luxi Block are closely related to the Tan–Lu Fault Zone. • The basins in the Luxi Block were involved in NE–SW compression (150–145 Ma), NE–SW extension (145–122 Ma) and N–S extension (63–32 Ma). • The Tan–Lu Fault Zone experienced sinistral strike-slip, normal faulting and dextral strike-slip in Late Jurassic–Paleogene. • The change from compression to extension at ∼145 Ma in the Luxi Block represents the initiation of craton destruction. The Tan–Lu fault zone (TLFZ), a lithosphere-scale fault in the eastern North China Craton (NCC), experienced multi-stage evolution characterized by alternating extension and strike-slip faulting in different tectonic setting. A series of Meso-Cenozoic sedimentary basins striking NW–SE to nearly E–W are distributed in the Luxi Block (LXB) to the west of the TLFZ. Recently, based on detailed fieldwork focusing on the sedimentary features and the boundary faults of these basins, the genetic relationship between basins and the TLFZ is disclosed in this study. The basins in the LXB were formed in the Late Jurassic–Paleogene, which were controlled by E–W and NW-SE-trending boundary faults. They were filled by the Late Jurassic fluvial coarse clastic rocks, the Early Cretaceous volcanic-clastic rocks, and the Paleogene fluvio-lacustrine sediments. Combined with the fault geochronology and paleo-stress restoration, three evolutionary stages are proposed: NE–SW compression in the Late Jurassic (150–145 Ma), NE–SW extension in the Early Cretaceous (145–122 Ma), and the N–S extension in the Paleogene (63–32 Ma), which were associated with the sinistral strike-slip faulting, extensional rifting, and dextral strike-slip faulting of the TLFZ, respectively. The basin evolution implies that the kinematic transition of the TLFZ occurred at the Earliest Cretaceous (∼145 Ma) and Early Paleogene (∼63 Ma). The tectono-transition from compression to extension in the LXB at ∼145 Ma might indicate the initiation of destruction of the NCC due to the adjustment from continental collision between the NCC and the South China Block (SCB) to back-arc extension of the Paleo-Pacific plate. The variation of extensional stress orientation in the Paleogene is interpreted to be related to the change of subduction direction of the Paleo-Pacific plate. [ABSTRACT FROM AUTHOR]

[Display omitted] • Revisiting West Qinling tectonic evolution during the Early Triassic by 8584 zirconU-Pbdata. • TheEarlyTriassicWestQinlingOrogenicBeltwaspossiblyacontinentalarc. • TheLongwuheFormationwasformedinaforearcsetting. • TheWest Qinling and Qilian orogenic belts and North China Block were the main sourcesfortheLongwuheFormation. The West Qinling Orogenic Belt (WQOB) in central China witnessed the closure of the Paleo-Tethys Ocean and the subsequent amalgamation between the North China Block and the South China Block during the Permian-Jurassic. However, the pre-closure Triassic tectonic evolution of the WQOB remains poorly constrained. Thick Triassic sedimentary successions are well preserved in the Xiahe-Hezuo district and provide significant information for investigating the tectonic setting in the WQOB. Here we present U-Pb ages and Hf isotopic compositions of detrital zircons from a pebbly slate of clastic sedimentary rock that comprises the Longwuhe Formation of the WQOB, the Xiahe–Hezuo district, Central China. The detrital zircon U-Pb ages vary from 2525 Ma to 244 Ma and are distributed in five periods, i.e., 2525–2225 Ma, 2013–1676 Ma, 1127–883 Ma, 501–438 Ma, and 330–244 Ma. The youngest detrital zircon age peak of ca. 250 Ma constrains the maximum depositional age of the Longwuhe Formation to the Early Triassic. Provenance analysis indicates that the WQOB, the eastern Qilian Orogenic Belt, and the southern North China Block serve as the main source of the pebble-bearing slate. The detrital zircon of 330–281 Ma in the WQOB implies likely the presence of an Early Triassic continental arc. Integrated results of the regional structure, geochronology, and geochemistry of the Triassic granites in the WQOB suggest that the Longwuhe Formation was probably deposited in a forearc setting at ca. 250 Ma and followed immediately by arc magma intrusion in Early Triassic. Thus, the WQOB was possibly generated as a continental arc associated with the northward subduction of the Qinling Paleo-Tethys Ocean lithosphere during the Early Triassic. [ABSTRACT FROM AUTHOR]

[Display omitted] • The Late Cretaceous clastics in the Shoushan Basin are divided into five microfacies. • The microfacies heterogeneity is due to the differential implication of the diagenetic factors. • These rocks are divided into some reservoir rock types to get a more accurate reservoir modelling. • The very fine massive sandstone microfacies has the best reservoir quality due to its dissolution. • The laminated siltstone and the bioturbated limestone are highly cemented by silica cement. The Late Cretaceous Upper Bahariya Member is one of the most prolific reservoir sequences in the North Western Desert of Egypt. In this paper, we describe core samples of the Upper Bahariya Member, including core photos, conventional core analysis, petrographical description, scanning electron microscope images, and XRD analysis. Samples for this study are from the reservoir sequence in four wells selected from the Shurouk Field in the Shoushan Basin to delineate the impact of the constraint mineral composition on the reservoir quality. The objective of this study is to get an accurate reservoir characterization of this reservoir by applying the rock typing technique to the studied sequence where four Lithofacies Associations (LFA1, LFA2, LFA3, and LFA4) and four corresponding Reservoir Rock Types (RRT1, RRT2, RRT3, and RRT4) were assigned. These are defined as 1) very fine massive sandstone (LFA1, RRT1), 2) laminated, cross-bedded and bioturbated sandstone (LFA2, RRT2), 3) laminated, highly argillaceous and ferruginated sandstone and siltstone (LFA3, RRT3), and 4) laminated and ferruginated siltstone and well cemented bioturbated limestone (LFA4, RRT4). Petrographically, these lithofacies were categorized into five microfacies; 1) glauconitic quartz arenite, 2) subfeldspathic arenite, 3) glauconitic sublithic arenite, 4) ferruginated subfeldspathic wackes, and 5) sandy fossiliferous packstone microfacies. Conventional core samples include bulk and grain densities (ρ b and ρ g , respectively), helium porosity (∅ He), and horizontal and vertical permeabilities (k H and k V , respectively). The application of the Dykstra-Parsons technique to the available permeability data indicates that the studied sequence is extremely heterogeneous (heterogeneity factor (V) = 0.90). Based on the available samples, the normalized porosity index (∅z), reservoir quality index (RQI), flow zone indicator (FZI), and the discrete rock type values (DRT) were estimated to determine the reservoir quality. The RRT1 samples are characterized by the best reservoir properties (av. ∅ He = 14.7%, av. k H 42.0 = md, av. RQI = 0.47 µm, av. FZI = 2.87 µm, and av. DRT = 13), whereas the lowest reservoir quality is assigned to the RRT4 samples (av. ∅ He = 18.8%, av. k H 0.30 = md, av. FZI = 0.15 µm, av. RQI = 0.04 µm, and av. DRT = 7). The low reservoir quality of the RRT4 is primarily attributed to the predominance of lower quality features (compaction effect, cementation, and presence of glauconite and authigenic minerals). Following the Improved Stratigraphic Modified Lorenz (ISML plot), the Upper Bahariya reservoir is subdivided into five Hydraulic Flow Units (HFUs) such as the HFU-2, and the HFU-4 that are considered superconductive flow units that alternate with three poorly hydraulic conductive HFUs (HFU-1, HFU-3, and HFU-5). The present integrated sedimentological and petrophysical workflow is considered a significant study of the Shoushan basin which can improve exploration activities as well as production optimization. In addition, dividing the studied clastic sequence into five microfacies association and four reservoir rock types can be extended to other equivalent subsurface Late Cretaceous clastic sedimentary rocks in the vicinity and other basins. [ABSTRACT FROM AUTHOR]

[Display omitted] • Sandstone in the upper part of the Qawasim Formation is the main reservoir in the El Tamad field. • Primarily, the sandstone is arenite in composition, well sorted with sub-rounded to rounded grains. • Diagenesis enhanced the reservoir quality of the sandstone with low-cement content, poor compaction and weak fracturing. • Clastic rocks of the Qawasim Formation were deposited in a shelf environment as stacked barrier-island bars. • Carbonate rocks of the Qawasim Formation were deposited in a shelf lagoon with open circulation. The Nile Delta region is the main gas-producing province in Egypt. Late Miocene sediments are the target of drilling in the onshore Nile Delta where it has the potentiality to store and produce hydrocarbons. Five wells of the Messinian Qawasim Formation at El Tamad Field were selected for the present study. Detailed petrographic investigations were carried out to reveal the depositional and diagenetic features of the Qawasim Formation rock units. Two main facies were distinguished in the studied formation: clastic and carbonate facies. The clastic rocks include conglomerate, sandstone and shale, while the carbonate rocks include limestone and dolostone. Depositional, diagenetic and petrophysical parameters of the sandstones of the Qawasim Formation reflect that this rock unit an excellent reservoir for hydrocarbon. These microfacies display depositional features such as well sorting, open packing and poor cementation in both coarse and fine-grained microfacies. The porosity of sandstone was enhanced by diagenetic processes such as dolomitization of calcite cement and low compaction that resulted in grain cracking, while the dissolution of feldspars had a subordinate impact on increasing porosity due to their low abundance and the resultant authigenic clay minerals. [ABSTRACT FROM AUTHOR]

[Display omitted] • Six tectonic events were inversed from fault-slip analysis in the Nanling Tectonic Belt. • Four Cretaceous tectonic events resulted from the Paleo-Pacific subduction. • Two Paleogene tectonic events were due to the far field effect of the India-Asia collision. Cretaceous tectonic events and Cenozoic geodynamics of the central South China Block are still under debate. A long-term extensional regime or two extension-contraction tectonic cycles were proposed for the Cretaceous tectonic evolution. While Cenozoic geodynamics of the central South China Block were ascribed to the Pacific subduction or the far field effect of the India-Asia collision. Kinematic analysis of fault-slip data were carried out for the Cretaceous to Paleogene Chaling-Yongxing Basin and the Lianshan-Yangshan Domain in the Nanling Tectonic Belt. Kinematic analysis of fault-slip data (409 groups of faults and striations) reveal four Cretaceous tectonic events and two Paleogene tectonic events. i) The early Early Cretaceous extensional regime is represented by a NW-SE horizontal minimum principal stress and a vertical maximum principal stress, which generated NE-striking boundary normal faults of Early Cretaceous basins. ii) The late Early Cretaceous strike-slip regime is characterized by a N-S horizontal maximum principal stress and a E-W horizontal minimum principal stress, which led to tectonic inversion of Early Cretaceous extensional basins and nearly N-S-striking folding of the Lower Cretaceous. iii) The early Late Cretaceous extensional regime is represented by a NW-SE horizontal minimum principal stress and a vertical maximum principal stress, which activated the NE-striking boundary normal faults of Late Cretaceous basins. And iv) the latest Late Cretaceous strike-slip regime is characterized by NW-SE horizontal maximum principal stress and a NE-SW horizontal minimum principal stress, which led to tectonic inversion of Late Cretaceous extensional basins and NNE-striking folding of the Upper Cretaceous. Orientations of maximum or minimum principal stresses imply that two extension-contraction tectonic cycles during the Cretaceous resulted from the Paleo-Pacific subduction. Two Paleogene tectonic events are v) the strike-slip regime characterized by NE-SW horizontal maximum principal stress and a NW-SE horizontal minimum principal stress, and vi) the subsequent extensional regime represented by a NE-SW minimum principal stress and a vertical maximum principal stress. The former generated NW-striking reverse faults and reactivated strike-slipping of NE- and NW-striking conjugate faults whereas the latter formed NW-striking normal faults in the Lower Paleogene clastic rocks. Orientations of maximum or minimum principal stresses indicate that two Paleogene tectonic events in the central South China Block were attributed to the far field effect of the India-Asia collision and subsequent stress relief. [ABSTRACT FROM AUTHOR]

[Display omitted] • Mechanical compaction is the most vitally destructive factor in shallow reservoirs. • Cementation especially late calcite is another crucial diagenesis in eodiagenesis. • Dissolution provides limited secondary pores in shallowly buried reservoirs. • Late carbonates present at the sand body edge enhance reservoir heterogeneity. • Late calcite cements of the clastic rocks were sourced from adjacent mudstone. A typical shallowly buried (800–2000 m burial depth) coarse-clastic, nonmarine, fan-deltaic reservoir is well developed in the Eocene Shahejie Formation, Damintun Sag, Bohai Bay Basin, China. In this study, diagenesis and its control on the reservoir quality of fan-deltaic sandstones and conglomerates in the Shahejie Formation were investigated in detail by petrographic and geochemical analyses, including cathodoluminescence, X-ray diffraction, scanning electron microscopy, electron probe microanalyses and X-ray fluorescence. The reservoir sandstones and conglomerates mainly consist of moderately sorted feldspathic litharenite, which has undergone various diagenetic processes such as mechanical compaction, cementation, and dissolution, and are currently in the eodiagenesis stage with porosity and permeability averaging 21.56% and 435.2 mD, respectively. Mechanical compaction and cementation caused an ∼45% reduction in the original reservoir porosity, especially the former, which exerted a more significant influence. In regard to cementation, the late calcite that formed at the mudstone-sandstone interface is more destructive and enhances reservoir heterogeneity, and its source material is believed to be primarily derived from the adjacent mudstones in conjunction with oil and gas charging. Feldspar dissolution plays a limited constructive role in reservoir properties by creating ∼10% secondary porosity and changing reservoir wettability to oil wet through the formation of authigenic kaolinite. As a result, massive primary pores (∼90% of the total pores) in the shallowly buried sandstones and conglomerates in the Eocene Shahejie Formation are still preserved. This systematic study is expected to be applicable in a general way to other shallowly buried terrestrial clastic reservoir systems. [ABSTRACT FROM AUTHOR]

[Display omitted] • A provenance change from immature to mature arc is identified in the reconstructed Permian stratigraphy of the Hida Gaien belt. • The Permian stratigraphy and detrital zircon U–Pb ages are similar in the Hida Gaien belt and the eastern Central Asian Orogenic Belt. • The Permian strata were deposited in arc-related basins on 500–400 Ma basements along a single subduction zone of the Paleo-Pacific Ocean. The Permian volcano-sedimentary strata of the Hida Gaien belt of SW Japan are characterized by Lower Permian felsic tuffs and tuffaceous clastic rocks, Middle Permian andesites and sandstones rich in volcanic detritus, and upper Middle to Upper Permian feldspathic sandstones and mudstones. A combination of petrographic and geochemical analyses together with zircon U–Pb dating for the sandstones reveals a provenance change from an immature undissected arc with active felsic and intermediate volcanism during the Early–Middle Permian to a mature arc with basement uplift during the Late Permian. The Upper Permian sandstone yields syn-depositional zircons with 500–400 Ma zircons. This age distribution suggests that sediment was derived from the Permian arc and early Paleozoic basement. Similar characteristics to Permian strata in the Hida Gaien belt are recognized in the eastern Central Asian Orogenic Belt in terms of detrital zircon ages and the change in dominant lithology from volcanic to clastic rocks. In particular, Permian strata of the Jilin area (NE China) are lithostratigraphically similar to those of the Hida Gaien belt and have similar detrital zircon U–Pb ages. As such, Permian strata in both areas would have been deposited proximal to each other in the same tectonic setting along a single subduction zone in the western Paleo-Pacific Ocean. [ABSTRACT FROM AUTHOR]

[Display omitted] • The reservoir quality of sandstones with coarser grain and good sorting is better. • Compaction reduced pore spaces of sandstones formed in the braided river by 84.49%. • An appropriate amount of kaolinite was conducive to the development of reservoir. • Quartz cements do not have a major control on the reservoir quality. • The poorer the sorting, the greater the compaction index and the cementation. The impacts of deposition and diagenesis on sandstone reservoir quality have been extensively discussed over the years. But the research on how depositional factors control the reservoir quality by affecting diagenesis is rarely involved. The Permian System in the northern Ordos Basin is composed of clastic rocks, and sandstones formed in a braided river sedimentary system (braided channel and braided bar) are one of the most important reservoirs. Sandstones formed in the braided channel have inferior sorting, thinner depositional thicknesses, and higher contents of rock fragments and calcite cement. The total thin-section porosity, porosity and permeability of the sandstones are 5.9%, 9.76% and 0.75 × 10−3 μm2, respectively. The grain size and sedimentary thickness are positively correlated with the reservoir quality, and the secondary pores of the well-sorted sandstone are more developed. Sedimentary compaction resulted in average reductions of 85.69% and 82.76% in sandstones formed in the braided channel and braided bar, respectively. An appropriate amount of kaolinite (<6%) was conducive to the development of reservoir quality. Calcite cements have reduced the pore spaces, whereas quartz cements do not have a major control on the reservoir quality. Diagenesis directly impacts reservoir quality, whereas depositional factors determine the preference and strength of diagenesis. The strength of dissolution is greater in the well-sorted sandstone, and the poorer the sorting, the greater the compaction index and cementation. The grain size, sorting, and deposition thickness control the sandstone reservoir quality by affecting the compaction strength, cement content, and dissolution. [ABSTRACT FROM AUTHOR]

• Dolostones dominate the Mesoproterozoic Gaoyuzhuang Formation (~1543 m thick). • The REE patterns for the dolostones are characterized by positive La and negative Ce anomalies. • REE fractionation occurred during the processes that formed the Precambrian dolostones. • Dolomite formation probably occurred while the sediments were on the seafloor. • Early diagenetic dolomitization may have been mediated by a mixture of freshwater and seawater. The Mesoproterozoic Gaoyuzhuang Formation (1.54–1.6 Ga), which is up to 1543 m thick, is a dolostone-dominated succession that originated in the Yanshan-liaoxi rift zone. In ascending order, this formation comprises Members 1 to 4. Member 1 is formed of clastic rocks and dolostones, whereas Members 2 and 4 are formed largely of dolostones. Member 3, which is divided in ascending order into three units (Members 3-L, 3-M, 3-T), is a succession of intercalated limestone and dolostone that have total rare earth elements (ΣREE) ranging from 0.5 to 116 ppm and variable Post-Archean Australian Shale (PAAS) normalized profiles. Carbonates from Member 3-M have REE profiles characterized by positive La and Y anomalies, a negative Ce anomaly, and a weak positive Eu anomaly. Relative to Member 3-M, carbonates from Member 2 and Member 3-L have flat REE profiles characterized by enriched light REEs, negative La and Ce anomalies, a positive Eu anomaly, and a lower Y/Ho ratio. Carbonates from Member 3-T and Member 4, relative to those from Member 3-M, are slightly more depleted in light REEs, lack a La anomaly, are enriched in Eu, have less depletion in Ce, and have similar Y/Ho ratios. Correlations between the dolomite content of samples and their [Pr/Sm] PAAS , [La/La*] PAAS , [Ce/Ce*] PAAS , and [Gd/Gd*] PAAS ratios indicate that dolomite-forming processes were probably associated with REE fractionation that reflects mixing between seawater and freshwater. Therefore, the REEs in Mesoproterozoic dolostones have the potential of being used as proxies for constraining the diagenetic environment under which the dolomites formed. [ABSTRACT FROM AUTHOR]

References 1 A. Aouizerat, W. Xiao, K. Schulmann, B.F. Windley, J. Zhou, J. Zhang, S. Ao, D. Song, P. Monie, K. Liu, Accretion, subduction erosion, and tectonic extrusion during late Paleozoic to Mesozoic orogenesis in NE China. 2020, 4 L. Feng, S. Lin, L. Li, D.W. Davis, C. Song, J. Li, S. Ren, X. Han, Y. Ge, K. Lu, Constraints on the tectonic evolution of the southern central Asian orogenic belt from early Permian-middle Triassic granitoids from the central Dunhuang orogenic belt, NW China. 2020, 10 H.T. Ma, X. Ma, J.F. Chen, B. Chen, C. Li, L.M. Zhou, H.Z. Yang, The Zhangjiatun igneous complex in the southeastern margin of the Central Asian Orogenic Belt, NE China: Evidence for an Early Paleozoic intra-oceanic arc. Shi, Q. Hou, C. Wu, Q. Yan, H.Y. Wang, N. Cheng, Q. Zhang, Z.M. Li, Paleozoic Sanweishan arc in the northern Dunhuang region, NW China: The Dunhuang block is a Phanerozoic orogen, not a Precambrian block. [Extracted from the article]

• Triassic sandstones in the West Qinling Mts. mainly comprise feldspathic litharenite and lithic arkose. • Sediments are mainly derived from ca. 273 Ma, 435 Ma and 1869 Ma sources. • Deposition occurred in a forearc basin in response to northward subduction. Lower to Middle Triassic clastic rocks in the West Qinling Mountains along NE margin of the Qinghai-Tibet Plateau are generally regarded as part of the Songpan-Ganzi flysch Basin. However relatively little attention has been paid to the age and provenance of these units. New petrological and geochemical results demonstrate that these sediments accumulated along an active continental margin and are dominated by feldspathic litharenite and lithic arkose with low mineral and compositional maturity. They were derived primarily from a continental arc source dominated by intermediate to felsic igneous rocks, with a minor contribution from older metamorphosed and sedimentary sources. Turbidite samples yielded two primary detrital zircon U-Pb age populations of ca. 273 Ma and ca. 435 Ma, which is different from the Early Triassic (ca. 252 Ma) and Middle Silurian (ca. 427 Ma) age populations that dominate the Songpan-Ganzi Basin. These data together with paleocurrent results indicate that the South Qilian Belt was the primary source origin because this belt contains both early Paleozoic Andean-type igneous and magmatic rocks and has a basement of Precambrian metamorphosed rocks. Regionally, an Andean-type arc traverses the South Qilian belts and extends into the West Qinling Mountains and Kunlun Orogen, which formed by north-directed subduction of the Paleo-Tethyan Ocean during the Early to Middle Triassic. Voluminous detritus that originated from the Qilian and Kunlun orogens as they were uplifted and eroded was transported to the south and deposited in the forearc area in front of the A'nimaqen-Mianlue suture. [ABSTRACT FROM AUTHOR]