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The southward extension of the Bangong-Nujiang Suture and the late Mesozoic tectonic affinity of the Tengchong Block have been subject to debate, and the Early Cretaceous magmatism in the eastern Tengchong Block provides a crucial window to address these issues. This paper reports comprehensive petrographic, geochemical, geochronological, and isotopic data of Early Cretaceous granitic rocks from the eastern Tengchong Block. Results show that these granitic rocks consist of monzogranites and granodiorites, with zircon U-Pb ages of 120.4–113.9 Ma. These granitic rocks are characterized by enrichments in large ion lithophile elements (e.g. Rb, U, K) and light rare earth elements, but depleted in high field strength elements (e.g. Nb, Ta, P, Ti), and have negative apatite εNd(t) values (−10.4 to −6.7) and negative zircon εHf(t) values (−11.7 to −1.2). The molar [Al2O3/(CaO + K2O + Na2O)] (A/CNK) values and whole-rock zircon saturated temperatures of the studied monzogranites of 1.04–1.09 and 714–799°C, respectively, indicate that they have I-type granite affinity. The presence of biotite indicative of I-type granite and the observation that P2O5 decrease with increasing SiO2 further indicated that the monzogranites have affinities of I-type granites. The petrography, geochemical and isotopic signatures of the studied monzogranites indicate that they originated from partial melting of mafic lower crustal rocks. The Na-rich granodiorites have elevated Na2O/K2O ratios and Na2O contents of 1.19–2.04 and 3.12–3.47 wt.%, respectively. These granodiorites also have relatively high Mg# values and the transition metal element Cr of 53.3–54.5 and up to 100 ppm, respectively. According to these isotopic and geochemical features and the occurrence of magnesiohornblende, we propose that the Na-rich granodiorites were derived from partial melting of ancient basaltic lower crust, with certain inputs of mantle materials in the magma source. Considering these results as well as published data, we finally propose that the Tengchong Block was likely the southeastern extension of the Lhasa Block and that these Early Cretaceous granitic rocks were formed in the setting of the volcanic arc due to westward subduction of the Bangong-Nujiang Tethys oceanic lithosphere beneath the Tengchong Block. [ABSTRACT FROM AUTHOR]

Jurassic-Cretaceous magmatic rocks are widely distributed in the Jiaodong area, North China. These magmatic rocks are closely associated with gold deposits, but their petrogenesis and geodynamic background are still controversial. The Late Jurassic-Early Cretaceous granitic rocks exposed in the Guocheng area, Jiaodong Peninsula are the focus of this paper. Zircon U-Pb dating, Hf-O isotope and whole rock geochemical analysis are used to determine the petrogenesis of these rocks. Combined with previous data, the geodynamic processes of granite formation in different time intervals are investigated which provide new petrological evidence for understanding the magmatic-mineralization and tectonic background of the Jiaodong area. Samples were collected from the Queshan and Shazibu plutons. The Queshan pluton is a mylonite granite, one sample of which yields a 206U-238Pb zircon age of 156 Ma, while the Shazibu pluton is a quartz monzonite, one sample of which records a 206U-238Pb zircon age of 117 Ma. The two plutons have variable zircon Hf-O isotopic compositions: zircon εHf(t) values of the Queshan pluton are −29.2 to −22.8, and δ18O values are 7.30–7.84 ‰, while the Shazibu pluton has relatively high zircon εHf(t) values (−21.6 to −21.0) and δ18O values of 7.48–8.43 ‰. Whole-rock geochemical data shows that the Queshan pluton has high Sr/Y (60.7–169) and (La/Yb)N (34.6–65.9) values and low Y (3.11–10.3 ppm) and Yb (0.29–0.85 ppm) contents, akin to adakites, whereas granites of the Shazibu pluton are A-type with high Zr+Nb+Ce+Y contents (354–420 ppm) and zircon saturation temperatures (752–795°C). Based on the geochemical and isotopic data, the Late Jurassic Queshan pluton is the product of partial melting of thickened lower crust of the North China Block, while the Early Cretaceous Shazibu pluton formed via fractional crystallization of mafic rocks derived from partial melting of the lower crust of the North China Block. Although both plutons were derived from the lower crust of the North China Block, the nature of the lower crust was modified by involvement of more depleted mantle-derived materials during the Early Cretaceous. From the Late Jurassic to the Early Cretaceous, the rock types (from the adakite to A-type granite) and the nature of the magma source suggest a shift in geodynamic processes. Combined with previous research, the Late Jurassic Queshan pluton is proposed to have formed under low-angle subduction of the ancient Pacific Plate, while the Early Cretaceous Shazibu pluton formed subsequently during Pacific Plate rollback and extension. The Early Cretaceous transformation of tectonomagmatic environments provided favourable conditions for the formation of large-scale gold deposits in the Jiaodong region. [ABSTRACT FROM AUTHOR]

Late Palaeozoic evolution of the Chinese Altai-East Junggar orogenic collage is vital for a better understanding of the accretionary evolution in the southern Altaids. This paper reports new geochronological, geochemical, and isotopic data for the magmatic rocks collected from the northern part of the Dulate arc. The ~304.6 Ma tonalite samples present typical adakitic features of high Sr (396–714 ppm), low Y (1.42–2.60 ppm), Yb (0.11–0.24 ppm), and high Sr/Y (177.25–440.23) ratios. Combining high Mg# (55.35–57.21) and depleted isotopic composition (εHf(t): +9.89 to +13.37 and εNd(t): +5.36 to +6.06), we suggest that they were derived from the partial melting of a subducted oceanic slab. The ~299.4 Ma monzogranite samples have high A/CNK values (1.08 to 1.25), CIPW normative corundum contents (1.28–3.25 wt.%), and positive εHf(t) (+5.14 to +8.63) and εNd(t) (+1.08) values, which are similar to S-type granite that may be generated by the melting of greywackes. The monzogranite (~286.9 Ma) and rhyolitic porphyry (~283.9 Ma) are high-K calc-alkaline and similar to the highly fractionated I-type granites with depleted isotopic features (εHf(t): +11.68 to +14.99 and +0.75 to +7.18, εNd(t): +5.91 and +6.18). The monzogranite and rhyolitic porphyry could have been derived from a depleted mantle source, but the rhyolitic porphyry probably suffered partial assimilation of the overlying crust materials. Combining regional rock associations of mafic-ultramafic complexes, adakitic rocks, high-Mg diorites, and A-type granites with close spatial-temporal relationship, we conclude that a mid-oceanic ridge of the Ob-Zaisan Ocean subducted southward beneath the Dulate arc during the latest Carboniferous to Permian. With the opening of the slab window, the upwelling asthenosphere provided high heat flux and triggered various magmatism in the upper plate. We propose that ridge subduction is one of the most effective mechanisms of continental growth in the southern Altaids. [ABSTRACT FROM AUTHOR]

Mesozoic igneous rocks are widely distributed in the South China Sea (SCS) and its adjacent areas and are exposed in the SCS, South China, Hainan, Indochina, Taiwan, the Philippines, and Borneo; these rocks are mostly dominated by granitoids. This paper presents a complete map of the Mesozoic igneous rocks of the SCS and its adjacent areas. This paper also presents an analysis of geological survey and published data in terms of seismic profiles, ages, geochemistry and isotopic systematics of the Mesozoic igneous complexes of the SCS and its adjacent areas. Three periods of igneous activity can be distinguished: (1) Permian – Triassic that spans from 250–201 Ma; (2) Jurassic (201–145 Ma); and (3) Latest Jurassic/Cretaceous to Maastrichtian (145–66 Ma), of which the Cretaceous is the best preserved and could possibly be the most widespread. Triassic igneous rocks are distributed in the northwestern and southern SCS (Qiongdongnan Basin, Yinggehai-Song Hong Basin, Beibu Gulf Basin, the Dangerous Grounds, and the Reed Bank); Jurassic igneous rocks are distributed in the northern and southern SCS (Pearl River Mouth Basin, Qiongdongnan Basin, Yinggehai-Song Hong Basin, Beibu Gulf Basin, and the Reed Bank); and Cretaceous igneous rocks are distributed in the northern, western and southern SCS. The igneous activity of the SCS is mostly distributed in the continent slope. Mesozoic igneous rocks of the SCS include at least 350 rock masses: the smallest being 0.182 km2, the largest being 5,5,502 km2, and the total area covering 688,539 km2. Mesozoic magmatism in the SCS and its adjacent areas migrated oceanward (southeastward). Our new seismic profiles and the wells from the literature highlight that Jurassic granites occur not only inland of South China but also in coastal South China and the northern and southern SCS. The YING6 well in the northern SCS encountered andesite with an age of 68.24 Ma, which is the youngest age found for the SCS Mesozoic volcanic rocks. The XY1 well in the western SCS encountered granite with an age of 68.9 Ma, which is the youngest age found for the SCS Mesozoic intrusive rocks. The WZ12-3-1 well in the northern SCS encountered granite with an age of 243.3 Ma, which is the oldest age found for the SCS Mesozoic intrusive rocks. The encountered dacite ages (219.1 ± 1.4 Ma) of the NK-1 well in the southern SCS were the oldest ages found for the SCS Mesozoic volcanic rocks. The thickest Mesozoic igneous rocks (>1022.5 m) were encountered in the NK-1 well. Igneous rocks in the SCS and its adjacent areas are closely related to tectonic movements such as faults, plate movement, and mantle-derived igneous fluid ascent. They are controlled by the subduction of the Tethys lithospheric and Paleo-Pacific domains. [ABSTRACT FROM AUTHOR]

In this paper, we present an integrated study of petrology, zircon U–Pb geochronology, whole-rock geochemistry, and zircon Lu–Hf isotopes for the basic–intermediate dykes in the western Gonghe basin, northeastern Qinghai–Tibetan Plateau. LA–MC–ICP–MS zircon U–Pb dating indicates that these dykes were emplaced in the Middle Triassic (240 ± 1.6 Ma). Geochemically, these basic–intermediate dykes are characterized by enrichments in light rare earth elements (LREEs) and large-ion lithophile elements (LILEs; e.g. K, Rb, and Pb), coupled with depletions in high-field-strength elements (HFSEs; e.g. Nb, Ta, and Ti). These geochemical features, along with the relatively low zircon εHf values (−7.2 to 1.6), suggest that these mafic dykes were originated from enriched mantle metasomatized by subduction-related fluids in a back-arc extensional environment. Literature investigations indicate that Middle Triassic mafic dykes are widespread in central China and are geochemically of arc affinities. Therefore, a regional back-arc extensional event occurred in central China during Middle Triassic time, which was likely caused by rollback of the subducting Kunlun–Animaqin Paleo-Tethyan slab. [ABSTRACT FROM AUTHOR]

The Naxiguole Banded Iron Formation (BIF), located in the Eastern Kunlun Orogenic Belt, Northwest China, is hosted by the Jinshuikou Group and has a Fe of 75 Mt at a grade of 15–28.83 wt.% Fe. In this paper, we use integrated petrological, geochemical, and geochronological data to limit the age and origin of the Naxiguole BIF. Country rocks mainly comprise marble, felsic paragneiss, plagioclase amphibolite schist, and biotite plagioclase gneiss. The features of sedimentary structure (blastopsammitic texture and blastobedding structure) and trace elements (e.g. La, Ni, Zr) from the country rock indicate that their protoliths are sedimentary rock. The 141 detrital zircons from the Jinshuikou Group yield a minimum age of 908 Ma, which can be considered the upper limit for the Naxiguole BIF. According to the age (602 Ma) of the mafic rocks intruding into the Jinshuikou Group, it is reasonable to assume that the formation age of BIF can be limited at 908–602 Ma (i.e. Neoproterozoic). The high contents of Al2O3 + TiO2 (3–6 wt.%), ΣREE (36–135 ppm) for BIF samples suggest that terrestrial clastic material contributed to BIF formation. The BIF samples show seawater-like features, such as depletion in LREEs, positive Y anomaly and high Y/Ho ratios (30.7–57.5, average = 42.5), implying that the Naxiguole BIF precipitated from seawater. The positive Eu/Eu*PAAS anomalies (average 1.52) suggest the influence of high-T hydrothermal fluids. Based on positive Eu anomalies and high terrestrial clastic components and no obvious Ce anomalies, the Naxiguole BIF was formed in an anoxic or suboxic sedimentary basin within active continental island arc, and is similar to Superior-type BIFs worldwide. [ABSTRACT FROM AUTHOR]

The 2022 Winter Olympics will be held in the Beijing-Zhangjiakou area, which is located in the eastern North China Craton (NCC) and contains a comprehensive geological record from the Archaean to Cenozoic. In this paper, we first review the geology of the Beijing-Zhangjiakou area, then, combined with data from the rest of the NCC, we discuss the geological evolution of the area in the context of the NCC. The geological and tectonic evolution of the Beijing-Zhangjiakou area can be regarded as a proxy or analogue for the geological history of the whole of the NCC. Six stages have been divided as follows: 1) Neoarchean massive continental crust growth; 2) Paleoproterozoic cratonization; 3) Meso-Neoproterozoic multi-stage rifting; 4) Palaeozoic marginal orogeny; 5) Mesozoic craton destruction; and 6) Cenozoic intra-plate extension. We hope this paper will be helpful to both geologists and non-geologists who will attend the 2022 Beijing-Zhangjiakou Winter Olympics and may be interested in rocks and geology around the Winter Olympic sites. [ABSTRACT FROM AUTHOR]

Cenozoic magmatism was highly active in the South China Sea (SCS), and mostly dominated by basalts. The magmatic rocks are mainly distributed in the lower slope and subbasins of the SCS, in addition to sporadic and small-scale Cenozoic volcanism on the SCS shelf. This paper presents a complete map of the Cenozoic magmatic rocks of the SCS with magmatic rock boundaries. This paper also presents an analysis of geological survey and published data in terms of seismic profiles, ages, geochemistry and isotopic systematics of the Cenozoic magmatic complexes of the SCS and adjacent areas. Many of wells or dredges are located in magmatic rocks identified by seismic profiles. Three periods of magmatic activity are distinguished: (1) a pre-spreading period (>33 Ma); (2) a syn-spreading period (33–15 Ma) and (3) a post-spreading period (<15 Ma). The thickest volcanic rocks encountered more than 1000 m (possibly Oligocene to Miocene) in the Boayan 1/1A well in the Palawan Trough of the southern SCS during Cenozoic. The oldest magmatic rocks are andesites (62.5 ± 2.2 Ma) in the northern SCS (offshore) and andesites (65 ± 3 Ma) in Penghu (on land). The latest modern magmatic activity was detected in 1923 offshore of a submarine volcanic eruption (10°09´29″N, 109°00′50″E, 20 m below sea level) and along the shore of a volcanic eruption in the Philippines. Cenozoic magmatic rocks of the SCS include at least 1008 rock bodies: the smallest is 0.00012 km2, the largest is 1528 km2 and the total area covers 46,309 km2. The Yangjiang-Yitong fault and Zhongnan-Reedbank fault divide the magmatic rocks into two different sections in the eastern and western SCS. The ages of the magmatic rocks in the eastern SCS are mostly older than those in the western SCS. The magmatic rocks in the northern, southern, eastern, western SCS and adjacent areas, and SCS basin are related to extension, subduction+collision, subduction, extrusion, extension+cooling+subsidence, respectively. [ABSTRACT FROM AUTHOR]

Li–Be mineralization in the northeastern Pamir is the most westerly portion of the newly defined Western Kunlun–Songpan–Ganze rare metal belt in China. This paper discusses the geochemistry and isotopic U–Pb–Sr–Nd–Hf systems of two Triassic granites and Li–Be pegmatites, trying to identify their genetic relationship. Our study shows that although the biotite monzogranites, the muscovite granites, and the Li–Be pegmatites have similar zircon and coltan U–Pb ages of 210 Ma, continuous crystallization could not completely account for their compositional and Sr–Nd–Hf isotopic diversity. In comparison with the biotite monzogranites, the muscovite granites exhibit strongly fractionated characteristics, with higher levels of SiO2, K2O, P2O5, Li, Be, Cs, Rb, and Ta, and are sourced from a partial melt of meta-pelite rocks, showing a genetical relationship with the Li–Be pegmatites. A model of volatile accumulation is an attempt to interpret some characteristics of the strongly fractionated muscovite granites and Li-Be pegmatites, which show dramatically elevated contents of P2O5 of 0.20–0.23% to Li–Be pegmatites of 0.4–2.64%, respectively. P2O5 might be an agency of the accumulation of fluxing compositions also including B, F, and H2O. Succeeding pegmatite-forming fluid exsolution and selective removal of Ca–Na–K to precipitate feldspar minerals far away from the parent granites should be accountable for some strongly fractionated characteristics in the residual melt, e.g. the enrichment of Rb, loss of Sr and Ba, and elevated negative Eu anomaly. Furthermore, this selective extractant of alkalis metal triggered by the accumulation of flux notably enhanced the contents of Li and Be in the remaining melts by three times, which might be also an important mechanism for the rare metal concentration in the Li–Be pegmatites by thousands of times. [ABSTRACT FROM AUTHOR]

The relationship between mafic magmatic enclaves (MMEs) and host granitoids is ongoing debate due to their significant roles in understanding deep magmatisms and geodynamic processes. This paper reports on Early Palaeozoic granitoids and associated MMEs from the Delingha pluton in the South Qilian Accretionary Belt (NW China) to constrain their petrogenesis and draw implications. The MMEs, occurring as ellipsoidal to rounded shapes, are andesitic and have the same crystallization age (~445 Ma) and mineral assemblage as the host granitoids. However, minor isotopic differences between them and compositional and textural disequilibria on minerals (e.g. plagioclase and amphibole) do not support a cumulate origin that the MMEs were formed at earlier stage of the same magmatic system, but forcefully reflect magma hybridization processes between mafic and felsic magmas, during which the hybridized magma was broken up into discrete enclaves by convective motion in the host felsic magma. Accordingly, the primitive compositions of the MMEs likely originated from metasomatized mantle wedge source, while mantle-derived melt underplated and partially melted the lower continental crust to form the host rocks with a certain mantle contribution. Thus, the Delingha pluton is the product of crust-mantle interaction at an active continental margin subduction setting rather than syn-collisional environment, indicating that subduction of the South Qilian Ocean located between the Central Qilian Block and the Oulongbuluke Block may have lasted till to ~445 Ma. [ABSTRACT FROM AUTHOR]

When the Neo-Tethys subduction initiated has been a subject of debate, perhaps due to the lack of reliable evidence. This paper reports geochronological, geochemical, and Hf isotopic data for recently identified gabbro as well as diorite exposed in the Chanv area of the Gangdese in the southernmost margin of the western Lhasa block, western China. Zircon U–Pb dating indicates the Chanv magmatic rocks formed in two stages: latest Permian (gabbro, 254.8 ± 1.5 Ma) and Late Triassic (gabbro, 214.2 ± 2.0 Ma; diorite, 202.8 ± 1.1 Ma). Geochemical and Hf isotopic analyses reveal that the Chanv magmatic rocks of both stages have contrasting characters. The latest Permian gabbro has apparently higher TiO2 concentrations (> 3 wt.%) than the Late Triassic gabbro (0.86–1.24 wt.%). Although they all are enriched in light rare-earth elements (LREEs), the latest Permian gabbro displays no depletions in Nb and Ta, while the Late Triassic gabbro and diorite are apparently depleted in these two elements. In addition, the zircons from the latest Permian gabbro are all characterized by positive εHf(t) values whereas those from the Late Triassic gabbro dominantly by negative εHf(t) values. Conventional plots using multi-elements or elemental ratios all indicate the latest Permian gabbro has inherent resemblance to intraplate oceanic-island basalt (OIB) whereas the Late Triassic gabbro and diorite are of distinct arc affinity. Therefore, The Chanv latest Permian–Late Triassic magmatic rocks testify a switch of the tectonic environment in the southernmost Eurasian margin from latest Permian post-break-up to Late Triassic arc-related setting and thus constrain the initiation of the Neo-Tethys subduction between 255 Ma and 214 Ma. [ABSTRACT FROM AUTHOR]

Late Mesozoic volcanic rocks are widespread in the Great Xing'an Range (GXR), Northeast (NE) China. However, details of the tectono-magmatic evolution during the Late Mesozoic are poorly understood. In this paper, new zircon U–Pb, Lu–Hf, and whole-rock geochemical data from Late Mesozoic volcanics in the southern GXR, are used to further constrain the tectono-magmatic evolution of the region. Late Mesozoic magmatism in the GXR, eastern Mongolia and southern Transbaikalia occurred during the Early Cretaceous (120–140 Ma) and Late Jurassic (150–163 Ma) periods. Late Jurassic trachyandesites-trachytes show a low rare earth element and moderate light rare earth element (LREE) enrichment with no Eu anomalies. Early Cretaceous trachytes are characterized by an LREE enrichment and negative Eu anomalies. Contemporaneous rhyolites exhibit a significant LREE enrichment, A–type granitoid affinity, and pronounced negative Eu anomalies. Different negative Nb, Ta, and Ti anomalies, and positive zircon εHf(t) values, indicate that the ~160 Ma trachyandesites-trachytes are derived from partial melting of the lithospheric mantle that was metasomatized by subduction-related fluids. The ~125 Ma trachytes and rhyolites were possibly generated by partial melting of the accreted Meso-Neoproterozoic lower crust. New and previously published geochemical, isotopic and geochronological data from the southern GXR, eastern Mongolia and East-Transbaikalia, suggest that Late Jurassic–Early Cretaceous volcanism in the southern GXR occurred during the post-collisional extension after the closure of the Mongol–Okhotsk Ocean. [ABSTRACT FROM AUTHOR]

The Ailaoshan shear zone developed plenty of Cenozoic granitic plutons, located between the Yangtze block in the east and the Simao block in the west. Although a mass of previous studies have enriched the understanding of petrogenesis of these plutons, there are few reports on the plutons within the Mojiang-Lvchun terrane, a suspect domain between the Yangtze and Simao blocks. Among two plutons investigated in this paper, the Fenshuiling pluton is characterized by strongly shoshonitic (K20 = 5.8–6.4 wt.%) nature, high Y (6.5–30.0 ppm) and Yb (0.88–2.97 ppm) contents, and has limited variations in La/Yb (8.6–20.5) and Dy/Yb (1.6–1.9) with increasing SiO2. In Mengha, the pluton is also strongly shoshonitic (K20 = 5.7–6.1 wt.%), high Y (18.7–32.3 ppm) and Yb (2.03–3.50 ppm) contents, and shares limited variations in La/Yb (17.0–17.6) and Dy/Yb (1.5–1.7) with increasing SiO2. These tendencies correspond with the differentiation from a shoshonitic mafic melt by olivine, clinopyroxene and plagioclase (gabbroic) dominated fractional crystallization. These plutons mainly composed of quartz syenites are characterized by island-arc basalt (IAB) patterns, which are consistent with those evolved by shoshonitic mafic melt derived from metasomatic lithospheric mantle within the Yangtze block. Zircon εHf(t) values of Fenshuiling and Mengha plutons range from −4.1 to −0.7 and −2.8 to −1.1, respectively, and their whole-rock εNd(t) values are −5.0 to −4.6 and −4.7 to −4.6, respectively. These Hf isotopes are similar to those from Neoproterozoic granitoids caused by a persistent Neoproterozoic subduction around the southwestern margin of the Yangtze block. This similarity supports a scenario that the enriched lithospheric mantle source area of these plutons caused by the Neoproterozoic subduction, also means that the suspect terrane belongs to the Yangtze block. The location of the Fenshuiling and Mengha plutons separated from those within the western margin of the Yangtze block is attributed to Cenozoic sinistral shearing events. [ABSTRACT FROM AUTHOR]

Large volumes of Early Cretaceous adakitic rocks crop out in northeast China. In this paper, we summarize their spatial-temporal distribution and geochemical characteristics. These adakitic rocks exhibit variable MgO, Cr and Ni contents, as well as potassium enrichments, in contrasting with those of the slab melting derived adakites. Positive εNd(t) and εHf(t) values and low 87Sr/86Sr(i) indicate significant Phanerozoic crust growth in NE China. Based on their geochemistry, these adakitic rocks are mainly derived from partial melting of juvenile lower crust. We interpret the melting to have resulted from extension and associated delamination. The ages of adakitic rocks are 141–120 Ma in the Xing'an region, 129–113 Ma in the Songliao basin, and 113–90 Ma in the Jiamusi region. Based on the lower-crustal-melting geochemical characteristics and spatial distribution of ages, we propose a new two-stage convergent bidirectional subduction model: Mongol-Okhotsk oceanic plate subduction and associated slab rollback in the west from 141–114 Ma and the Paleo-Pacific oceanic plate subduction and associated slab rollback in the east from 113–90 Ma. [ABSTRACT FROM AUTHOR]

China produced 17.1 billion cubic meters (BCM) of methane sourced from coal seams in 2015, of which 4.43 BCM is from wells drilled from the surface. This level of production is a clear indicator that China has gone into early stage large-scale coalbed methane (CBM) development. CBM resources in China have been extensively investigated since the 1980s. Research has focused on the geological controls of reservoir character. There have been significant advances over the last 37 years that have aided China’s CBM industry. CBM resources less than 2000 m in depth in China are estimated to be 36.81 trillion cubic meters, of which more than 84% occur in nine large-scale basins, such as the Qinshui, Ordos, Junggar, Qianxi, Erenhot, and Hailar. CBM accumulation and coal reservoir characteristics are controlled by the deposition, structure, coal rank, hydrology as well as other geological factors. Each basin has its own unique geological controls that influence the character of CBM reservoirs in both subtle and obvious ways. Coal reservoir geology in some basins or regions in China are still not well understood because of the complexity of the geological settings. At present, large-scale CBM production in China only occurs within the Qinshui and Ordos basins, mostly sourced from middle-to-high rank coal reservoirs. The CBM geology in other basins needs further investigation in order to achieve large-scale commercial production. To this end, the geological research in the paper should address issues such as how to stimulate economic gas flow from deep low permeability reservoirs and how best to efficiently produce from multiple horizons simultaneously. This paper summarizes these and other key issues that are significant scientific and technical challenges for the CBM industry within China. [ABSTRACT FROM AUTHOR]

This paper presents geochronological, geochemical, and zircon Hf–O isotope data for late Mesozoic intrusive rocks from the northeastern North China Craton (NCC), with the aim of constraining the late Mesozoic tectonic nature of the NE Asian continental margin. U–Pb zircon data indicate that the Late Mesozoic magmatism in the northeastern NCC can be subdivided into two stages: Late Jurassic (161 − 156 Ma) and Early Cretaceous (125 − 120 Ma). Late Jurassic magmatism consists mainly of monzogranites. These monzogranites display high Sr/Y ratios and the tetrad effect in their REE, respectively, and have negative εHf(t) values (−22.6 to −15.8). The former indicates that the primary magma was generated by partial melting of thickened NCC lower crust, the latter suggests that the monzogranites were crystallized from highly fractionated magma, with the primary magma derived from partial melting of lower continental crust. Combined with the spatial distribution and rock associations of the Late Jurassic granitoids, we conclude that the Late Jurassic magmatism in the eastern NCC formed in a compressional environment related to oblique subduction of the Paleo-Pacific Plate beneath the Eurasia. The Early Cretaceous magmatism consists mainly of granitoids and quartz diorites. The quartz diorites formed by mixing of melts derived from the mantle and lower crust. The coeval granitoids are classified as high-K calc-alkaline and metaluminous to weakly peraluminous series. Some of the granitoids are similar to A-type granites. The granitoid εHf(t) values and TDM2 range from −14.3 to −1.4 and 2089 to 1274 Ma, respectively. These values indicate that their primary magma was derived from partial melting of lower crustal material of the NCC, but with a contribution of mantle-derived material. We therefore conclude that Early Cretaceous magmatism in the northeastern NCC occurred in an extensional environment related to westward subduction of the Paleo-Pacific Plate beneath Eurasia. [ABSTRACT FROM AUTHOR]

Proterozoic igneous rocks in the southern margin of the North China Craton can place constraints on its crustal evolution. This paper reports geochemistry, zircon U-Pb ages, Sr-Nd isotopes and Lu-Hf isotopes for the Proterozoic Angou granite from the southwestern margin of the North China Craton (NCC). The Angou granite has zircon LA-ICP-MS U-Pb age of 1819 ± 14Ma (MSWD = 1.3, n = 37), which is synchronous with the Proterozoic Xiong'er Group in the southeastern margin of the NCC. The granite has A-type granite affinity: (1) high SiO2 (67.12% to 73.16%) and alkali (Na2O+K2O = 7.18% to 8.75%) contents, with K2O/Na2O ratios of 1.04 to 4.78; (2) high FeOT/MgO values (4 to 36); (3) significantly negative Eu anomalies (Eu*/Eu = 0.33 to 0.53) and negative Sr anomalies (38.1 to 102ppm); (4) high 104× Ga/Al (2.55 to 4.75, with an average of 3.43) values and Zr+Ce+Nb+Y (634 to 1022ppm) contents; (5) high zircon saturation temperatures (871 to 957°C). In combination with its slightly peraluminous (A/CNK = 1.02 to 1.26) nature, the Angou granite can be classified as slightly peraluminous A-type granite. It displays negative ɛNd(t) values of −2.0 to −3.9, variable εHf(t) values (−8.81 to +1.98) with Hf model ages of 2194 to 2721Ma, combined with its high Rb/Sr (1.05 to 3.26) and low Rb/Ba (0.08 to 0.18) ratios, suggesting that the Angou granite was derived from high temperature melting of tonalite in middle-lower crust. The formation of Angou A-type granite is consistent with the mafic dyke swarms and Xiong'er bimodal volcanic rocks in NCC, indicating a Paleoprotozoic extensional setting in the southwestern margin of the NCC. [ABSTRACT FROM AUTHOR]

The c.a. 259–260 Ma Emeishan mantle plume caused extensive flood basalts and associated peralkaline rocks; petrogenesis of these peralkaline rocks can provide detailed information about the melting process in the mantle. In this paper, we present detailed petrology, chronology, major and trace element geochemistry, Sr-Nd isotope and in situ zircon Hf isotope for an amphibole syenite from Panxi area, inner zone of the Emeishan large Igneous province (ELIP). The amphibole syenite has a zircon U-Pb ages of 260 ± 2 Ma (MSWD = 1.2, n = 22), which is synchronous with Emeishan mantle plume. It displays moderate SiO2 (64.89–65.67 wt.%), high Na2O (7.35–7.71 wt.%) and K2O (4.78–4.96 wt.%) contents, with A/CNK values of 0.86 to 0.90, with high Rittman index of 6.6 to 7.1, showing peralkaline affinity. It displays significantly negative Sr anomalies (133 to 200 ppm) and slightly negative Eu anomalies (Eu/Eu* = 0.78–1.04). The rock displays high εNd(t) values of +2.4 to +2.5. Zircons from the amphibole syenite display positive εHf(t) values from +8.9 to +11.0, with single-stage Hf model ages ranging from 0.47 to 0.55 Ga, combined with the well-developed correlation of TFe2O3, CaO/Al2O3, TiO2, Ni and Cr with MgO, suggesting the amphibole syenite was derived from the mantle source, and the fractional crystallization played a significant role in the generation of the magma. The MELTS model results show that Houzishan amphibole syenite can be formed by the high degree (~80%) fractional crystallization of ~24% clinopyroxene, ~4% orthopyroxene, ~35% plagioclase and ~5% oxide from parental magma resembling high-Ti basalts. These results indicate that Houzishan amphibole syenite represents the juvenile mantle-derived peralkaline melts addition to the continental lower crust in the inner zone of the ELIP and assimilating with minor crust material. [ABSTRACT FROM AUTHOR]

The mechanism that triggered large-scale Late Mesozoic magmatism in the northeastern Great Xing'an Range (NE GXAR) is strongly controversial. In this paper, we present whole rock geochemistry and zircon trace element, U-Pb and Hf isotopic data on the volcanic rocks in the Longjiang and Guanghua formations in the northeastern Xing'an Block. Zircons with ages of 120–119 Ma indicate that these volcanic rocks were formed in the Early Cretaceous. Combined with previous data, it is clear that volcanic rocks in the NE GXAR erupted between 128 and 108 Ma. The andesite samples of the Longjiang Formation show high contents of Al2O3, CaO, and MgO, significant negative Nb, Ta, and Ti anomalies; εHf (t) values of zircons from the andesite sample vary from +4.13 to +7.67, indicating an enriched mantle source. The rhyolites of the Guanghua Formation show high SiO2 and K2O concentrations, low P2O5, MgO, Cr, and Ni contents and Mg# values. The positive εHf (t) values (+5.72 to +10.58) with two-stage Hf model ages ranging from 939 to 701 Ma indicate that the rhyolites are derived from the partial melting of basaltic lower crust. Combined with the regional geological evolution, we conclude that the generation of the Early Cretaceous volcanic rocks in the NE GXAR might be triggered by the dehydration, disintegration, and foundering of the Mongol-Okhotsk Oceanic flat-slab and the subsequent upwelling of the asthenosphere. [ABSTRACT FROM AUTHOR]

This paper reports results from detrital zircon U-Pb geochronology, Hf isotopic geochemistry, sandstone modal analysis, and palaeocurrent analysis of the early Mesozoic strata within the Ningwu basin, China, with the aims of constraining the depositional ages and sedimentary provenances and shedding new light on the Mesozoic tectonic evolution of the northcentral North China Craton (NCC). The zircons from early Mesozoic sandstones are characterized by three major populations: Phanerozoic (late Palaeozoic and early Mesozoic), late Palaeoproterozoic (with a peak at approximately 1.8 Ga), and Neoarchaean (with a peak at approximately 2.5 Ga). Notably, three Phanerozoic zircons in the Early Triassic Liujiagou Formation were found to have positive εHf(t) values and characteristics typical of zircons from the Central Asian Orogenic Belt (CAOB). Therefore, the CAOB began to represent the provenance of sediment in the sedimentary basins in the northern NCC no later than the Early Triassic (261 Ma), implying that the final amalgamation of the NCC and CAOB occurred before the Early Triassic. The U-Pb geochronologic and Hf isotopic results show that the Lower Middle Triassic sediments were mainly sourced from the Yinshan-Yanshan Orogenic Belt (YYOB), and that a sudden change in provenances occurred, shifting from a mixed YYOB and CAOB source in the Middle Jurassic to a primarily YYOB source in the Late Jurassic. The results of the sandstone modal analysis suggest that the majority of the samples from the Lower Middle Jurassic rocks were derived from either Continental Block or Recycled Orogen sources, whereas all the samples from the Upper Jurassic rocks were derived from Mixed sources. The change in source might be ascribed to the southward subduction and closure of the Okhotsk Ocean and the resulting intense uplift of the YYOB during the Late Jurassic. This uplift likely represents the start of the Yanshan Orogeny. [ABSTRACT FROM AUTHOR]

Northeast (NE) China is characterized by large areas of Mesozoic and Paleozoic granitoids, whereas Cenozoic granitoids are scarce. This paper reports LA-ICP-MS zircon U-Pb ages and whole-rock geochemical data for late Paleocene-early Eocene granitoids from the Jiamusi Massif, NE China, in order to determine their petrogenesis and tectonic implications. Geochronological data indicate that the granodiorite and dioritic porphyry from the Wudingshan pluton formed at 51.5 ± 0.3 Ma and 56.3 ± 0.8 Ma, respectively. The biotite-quartz diorite, biotite granodiorite, and dioritic porphyry have high SiO2 (68.38-70.06 wt.%), Al2O3 (15.34-15.79 wt.%), and Na2O (3.96-4.49 wt.%) contents, low MgO contents (1.10-1.26 wt.%), A/CNK ratios of 0.99-1.11, and are classified as medium- to high-K calc-alkaline and weakly peraluminous I-type granitoids. They are enriched in LREEs and LILEs, and depleted in HFSEs, with Nb/Ta ratios of 10.4-15.0. Moreover, they have negative Nb-Ta-Ti anomalies, indicating that they were derived from continental crust. Combining with the previously published isotopic data and regional geological results, we suggest that the late Paleocene-early Eocene granitoids (56-52 Ma) were probably derived from partial melting of juvenile lower crust, and formed in an active continental margin setting, possibly related to subduction slab rollback of the Paleo-Pacific Plate. [ABSTRACT FROM AUTHOR]

Trace elements (TEs) in coal result in substantial pollutant emissions and cause serious damage to the ecological environment and human health in China. The emission and control of TEs, especially mercury, during coal combustion are of significant concern, and extensive studies have been performed in China in recent years. This paper reviews the emission characteristics and control strategies of mercury and other TEs during coal combustion in China. The occurrence of TEs in Chinese coals, including the average content of TEs in Chinese coals, the distribution of TEs in Chinese coals from different coal-forming periods, coal ranks, and coal-bearing regions are summarized. The emission characteristics of five specific TEs (Hg, As, F, Se, and Cr) during coal combustion in China are reviewed in detail. Effects of the coal type, combustion temperature, and combustion mode on the partitioning behaviour and emission characteristics of TEs are discussed. The effects of existing air pollution control devices of coal-fired power plants in China on the speciation and emission of TEs are discussed comprehensively. Various sorbents, such as activated carbon, fly ash, calcium-based sorbents, metal oxides, and mineral sorbents, used for TE removal are also summarized. Moreover, the removal performance of different sorbents for capturing certain TEs is compared comprehensively. Finally, future work for TE emission control in China is proposed. [ABSTRACT FROM AUTHOR]

The mid-Neoproterozoic tectonic setting of the Jiangnan Orogen (JO) is uncertain due to the ongoing debate regarding the history of interactions between the Yangtze and Cathaysia Blocks. Extensive magmatic rocks with ages >830 Ma are observed in the eastern JO and are reported to indicate their formation conditions; however, such magmatic rocks are rare in the western JO. This paper presents data from samples collected from two ultramafic intrusions in northern Guangxi province that yield SHRIMP U-Pb ages of 848 ± 7 and 836 ± 5 Ma. These two intrusions have similar geochemical compositions; are enriched in LILE (Rb, Ba, Th, and Pb) relative to HFSE (Hf, Zr, Nb, Ta, and Y), reflecting an arc-like signature; and are derived from the same source. The intrusions have positive εNd(t) and εHf(t) values, implying a depleted mantle source. Comparing the Neoproterozoic mafic-ultramafic rocks of the JO, differences exist between the rocks that formed at 860-830, 830-800, and 800-740 Ma in terms of their mantle sources and formation conditions. Considering the geochemical composition and ages of formation of the strata and the deep structure of the western JO, we speculate that the western JO was a back-arc foreland basin, which experienced shallow subduction-related and arc-like magmatism during the period between 860 and 830 million years. In contrast to the western JO, the eastern JO may have been a back-arc basin with oceanic crustal basement during that time. The JO formed between 830 and 800 million years in association with subduction-related collisional magmatism due to the amalgamation of the Yangtze and Cathaysia Blocks. Subsequently, magmatism occurred in the JO that resulted from the post-orogenic extension. [ABSTRACT FROM AUTHOR]

The northwest Zhejiang Province is a key domain for providing deep insight into the crust–mantle interaction and tectonic evolution of the South China block. In this paper, we collect geochemical, geochronological, and isotopic data of the Jurassic porphyries in this region, and investigated the Huangbaikeng ore-bearing porphyry in the Tongcun Mo–Cu deposit, using it as an example to uncover the porphyry petrogenesis and evaluate their metallogenic potential. Two varieties of the Huangbaikeng porphyry were distinguished: the medium- to coarse-grained type and medium- to fine-grained type. Zircon Sensitive High-Resolution Ion Microprobe U–Pb dating indicates that they were emplaced at 161.8 ± 2.8 and 162.7 ± 3.5 Ma, respectively, which are consistent with the molybdenite Re–Os ages of 163.9–161.8 Ma. The inherited zircons age spectrum significantly recorded a series of geological events, for example, assembly and breakup of the Columbia and Rodinia supercontinent, and the Triassic collision of Yangtze and North China blocks. Whole rock Sr–Nd and Jurassic zircon Hf isotopic data yield mostly negativeεHf(t) values (0.5 to −8.4) andεNd(t) values (−0.79 to −4.82). Besides the Huangbaikeng porphyry, all the Jurassic porphyries in the northwest Zhejiang Province have a wide range of SiO2contents (76.78–60.91 wt.%). They do not contain typical aluminous minerals (e.g. cordierite and garnet), and are mainly metaluminous to weakly peraluminous with high Na2O, low FeOT/MgO, and Zr + Nb + Ce + Y concentrations in composition. They thus fit the I-type granite definition. Some major and trace elements show strong correlations with SiO2, possibly indicating extensive fractional crystallization during their magma evolution. Tectonic discriminations imply that these plutons were likely formed in a volcanic arc regime possibly related to subduction of the Palaeo-Pacific plate. Sr–Nd–Hf isotopic data suggest a mixed source of the Mesoproterozoic crust and 30–50% mantle components. Compared with the adjacent Dexing Cu-bearing porphyies, which have more positiveεHf(t) andεNd(t) values with more significant mantle components (55–70%), the Jurassic porphyries in the northwest Zhejiang Province probably lack metallogenic potential to form a giant porphyry copper deposit as Dexing. [ABSTRACT FROM PUBLISHER]

Southern Hunan Province, located in the Cathaysia Block where the Shi–Hang zone and Nanling belt meet, is characterized by extensive Mesozoic magmatism and coeval polymetallic mineralization. The Huangshaping W–Mo–Pb–Zn–(Cu) deposit is representative in this area. However, the petrogenesis of the granitoids associated with the Huangshaping deposit, and their relationships with mineralization, remain undetermined. In this paper we focus on zircon U–Pb dating, whole-rock geochemistry, and Sr–Nd–Pb–Hf isotopic compositions in order to further our understanding of these issues, as well as their regional implications. The Huangshaping granitoids are characterized by two pulses of intrusive activity: a first-stage quartz porphyry and a second-stage felsite and granite porphyry, our new data show that the quartz porphyry and felsite formed at 160.5 ± 1.3 and 156.6 ± 1.4 Ma, respectively, representing a period of Late Jurassic magmatism. Granitic enclaves within the quartz porphyry crystallized at 160.2 ± 1.6 Ma, and zircons and apatites from the enclaves exhibit Hf isotopic and geochemical compositions that suggest a Palaeoproterozoic lower crustal melt as one end-member of the magma that formed the quartz porphyry, whereas another likely end-member was coeval mantle-derived magma, as indicated by the geochemistry and Sr–Nd–Pb–Hf isotopes. However, both the felsite and granite porphyry were probably derived from the melting of metamorphic basement rocks in the upper crust. The felsite clearly formed as a result of the rapid ascent and cooling of magma, whereas the granite porphyry underwent fractional crystallization. The magma sources and evolution of the granitoids, as well as their association with the Huangshaping mineralization, suggest that melting of upper crustal components controlled the W–Mo and Pb–Zn mineralization, whereas dehydration of a subducted slab provided the Cu mineralization in southern Hunan Province. [ABSTRACT FROM PUBLISHER]