15 results on '"Dong, Yunpeng"'
Search Results
2. Mid‐Mesozoic to Cenozoic multiphase deformation in the Bayanwula Tectonic Belt, northern China.
- Author
-
Yang, Xiangyang, Dong, Yunpeng, Feng, Yanbo, Xiang, Lingzi, Liu, Dongsheng, Sun, Jiaopeng, Shen, Na, and Li, Meng
- Subjects
- *
CENOZOIC Era , *DEFORMATIONS (Mechanics) , *SUBDUCTION , *THRUST , *GEOLOGY - Abstract
The Bayanwula Tectonic Belt (BTB) is located between the Alxa Massif and the Ordos Basin in the northwestern North China Craton (NCC). The Mid‐Mesozoic to Cenozoic deformation characteristics of the BTB is crucial for understanding the tectonic processes of eastern Asia during that time. Together with the regional geology, our field observation and structural analysis reveal that the BTB has undergone three phases of deformation since the Late Jurassic. The first phase of deformation (D1) is represented by NE–SW‐striking thrust faults involved in the Jurassic strata, indicating a phase of NW–SE shortening deformation. Based on the combination of angular unconformity between the Upper Jurassic and Lower Cretaceous strata, the timing of D1 is constrained at the end of Jurassic and dynamically related to the westward subduction of the Palaeo‐Pacific Plate during the end of the Jurassic. The second one (D2) is characterized by the ~NE–SW‐striking normal faults and Lower Cretaceous syn‐sedimentary strata on both sides of the BTB, which show that a phase of ~NW–SE extension deformation occurred in the Early Cretaceous, dynamically related to the rollback of the Palaeo‐Pacific Plate in the Early Cretaceous. The third stage of deformation (D3) is represented by the NW–SE‐striking folds that involved the Pliocene strata, as well as dextral strike‐slipping of the East Bayanwula Fault and the West Helanshan Fault, indicating a phase of NE–SW shortening at the end of the Pliocene. Dynamically, the D3 is related to the outward expansion of the Tibetan Plateau. [ABSTRACT FROM AUTHOR]
- Published
- 2023
- Full Text
- View/download PDF
3. Mesozoic contractional deformation in central East Asia: Constraints from deformation and sedimentary record of the Helanshan fold and thrust belt, North China Craton.
- Author
-
Li, Wei, Jiang, Dazhi, Dong, Yunpeng, Zheng, Zhouxu, Zhao, Jinxiang, Kang, Wenbin, and Zhang, Le
- Abstract
[Display omitted] • The Helanshan fold-thrust belts were formed in the Late Jurassic NW-directed contractional strain field. • The contractional deformation resulted from the westward subduction of the paleo-Pacific plate. • The Late Jurassic contractional deformation led to the initial uplift of the Helanshan. East Asia continent underwent complex deformation in the Mesozoic under multi-plate convergence. However, the response to the multiple plate convergence in the North China Craton remains enigmatic. The fold and thrust belt in the western margin of Ordos Basin in the west of the North China Craton, far away from the East Asian continental margin, provides an important clue to uncover the deformation process and its dynamic model in the East Asian continent. This paper focuses on kinematics and strain analysis of the fold and thrust belt in Helanshan through detailed field tectonic mapping. Combined with the Mesozoic stratigraphic and deformation records of adjacent areas, we try to comprehensively analyze the timing, styles, and processes of the Helanshan fold and thrust belt. This will provide significant constraints on the mechanisms of intraplate deformation in Asia. The Helanshan fold and thrust belt is located in the central part of North China, sandwiched between the Ordos block and Alxa block. The belt has well-developed fold and thrust structures and well-preserved Mesozoic coal-bearing sedimentary basins. The NNE-trending Helanshan fold and thrust belt is a typical thin-skinned structure developed in the western margin of the Ordos Basin. The fold and thrust belt was formed in the NW contractional strain field in the Late Jurassic in response to the westward flat subduction of the paleo-Pacific plate beneath the North China Craton along the eastern margin of the Asia continent. The contractional deformation in the Late Jurassic led to the initial uplift and formation of the Helanshan, which also became the Mesozoic western boundary of the Ordos Basin. [ABSTRACT FROM AUTHOR]
- Published
- 2022
- Full Text
- View/download PDF
4. Ordovician tectonic shift in the western North China Craton constrained by stratigraphic and geochronological analyses.
- Author
-
Sun, Jiaopeng and Dong, Yunpeng
- Subjects
- *
STRATIGRAPHIC correlation , *TIDAL flats , *AGE distribution , *CONTINENTAL margins , *PALEOGEOGRAPHY , *TURBIDITES - Abstract
The western North China Craton (W‐NCC) comprises the Alxa Terrane in the west and the Ordos Block in the east; they are separated by the Helanshan Tectonic Belt (HTB). There is an extensive debate regarding the significant Ordovician tectonic setting of the W‐NCC. Most paleogeographic reconstructions emphasized the formation and rapid subsidence of an aulacogen along the HTB during the Middle–Late Ordovician, whereas paleomagnetic and geochronologic results suggested that the Alxa Terrane and the Ordos Block were independent blocks separated by the HTB. In this study, stratigraphic and geochronologic methods were used to constrain the Ordovician tectonic processes of the W‐NCC. Stratigraphic correlations show that the Early Ordovician strata comprise ~500‐m‐thick tidal flat and lagoon carbonate successions with a progressive eastward onlap, featuring a west‐deepening shallow‐water carbonate shelf. In contrast, the Late Ordovician strata are composed of ~3,000‐m‐thick abyssal turbidites in the west and ~400‐m‐thick shallow‐water carbonates in the east, defining an eastward‐tapering basin architecture. Early Ordovician detrital zircons with ages of ~2,800–1,700 Ma were derived from the Ordos Block; the Late Ordovician turbidites were sourced from the western Alxa Terrane, based on zircon ages clustered at ~1,000–900 Ma. The petrographic modal composition and zircon age distribution imply a provenance shift from a stable craton to a recycled orogen in the Middle Ordovician. These shifts define a tectonic conversion from a passive continental margin to a foreland basin at ~467 Ma, resulting in the eastward progradation of the turbidite wedge around the HTB, the eastward backstepping of the carbonate platform in the east and the eastward expansion of orogenic thrusting in the western Alxa Terrane. This tectono‐sedimentary shift coincided with the advancing subduction of the southern Paleo‐Asian Ocean beneath the Alxa Terrane, generating the western Alxa continental arc and the paired retro‐arc foredeep in the east under a compressional tectonic regime. [ABSTRACT FROM AUTHOR]
- Published
- 2020
- Full Text
- View/download PDF
5. Geochemistry and detrital zircon records of the Ruyang-Luoyu groups, southern North China Craton: Provenance, crustal evolution and Paleo–Mesoproterozoic tectonic implications.
- Author
-
Li, Xi-Yao, Li, Sanzhong, Wang, Tong-Shan, Dong, Yunpeng, Liu, Xiao-Guang, Zhao, Shu-Juan, Wang, Kun, Sun, Jiao-Peng, Dai, Li-Ming, and Suo, Yan-Hui
- Abstract
Paleo- to Mesoproterozoic sedimentary rocks in the southern margin of the North China Craton (NCC) are represented by the Ruyang and Luoyu groups. We studied the sedimentary rocks from the Yunmengshan and Beidajian formations of the Ruyang Group and the Cuizhuang and Sanjiaotang formations of the Luoyu Group. Detrital zircon grains from these formations have U–Pb age populations of 3.64–3.31 Ga, 2.96–2.86 Ga, 2.72–2.59 Ga, 2.56–2.47 Ga, 2.45–2.0 Ga, 1.99–1.85 Ga and 1.84–1.65 Ga. The geochemical features of the sedimentary rocks suggest that some of the sediments were sourced from intermediate to felsic magmatic rocks. The age groups of the detrital zircon are roughly consistent with the tectono-thermal events in the southern margin of the NCC. The Hf isotopic compositions of detrital zircon from the sedimentary rocks in Ruyang and Luoyu groups suggest that significant crustal growth and reworking of the NCC took place during the Neoarchean and early- to mid-Paleoproterozoic, while crustal reworking at the Paleoarchean and late-Paleoproterozoic, and crustal growth at the Mesoarchean. We suggest the depositional times of the Ruyang Group and Luoyu Group are constrained to no older than 1.75–1.7 Ga and 1.7–1.65 Ga, respectively. Formation of late-Paleoproterozoic basins related to the strike slip and extrusion tectonics that cross-cut the NCC during the late Paleoproterozoic (<1.75 Ga), and the late Paleoproterozoic sedimentation once isochronous developed in the southern margin of the NCC through the Taihang region of the interior NCC and linked the Yanshan–Liaoxi regions of the northern NCC. Image 1 • The Ruyang-Luoyu groups were deposited during the late Paleoproterozoic to early Mesoproterozoic. • Detrital zircon grains indicate Precambrian crustal growth and reworking events in the NCC. • Formation of late-Paleoproterozoic basins related to the strike slip and extrusion tectonics. [ABSTRACT FROM AUTHOR]
- Published
- 2020
- Full Text
- View/download PDF
6. Triassic tectonic interactions between the Alxa Massif and Ordos Basin: Evidence from integrated provenance analyses on sandstones, North China.
- Author
-
Sun, Jiaopeng and Dong, Yunpeng
- Subjects
- *
SANDSTONE , *STRUCTURAL geology , *TRIASSIC Period , *GEOLOGICAL basins , *PROVENANCE (Geology) - Abstract
Graphical abstract Highlights • Triassic detritus in the northwestern Ordos were mostly sourced from the Alxa Massif. • Post-collision related basin formed in the northwestern Ordos at Middle-Late Triassic. • The Alxa Massif was the western extension of the North China Craton during Triassic. Abstract The Helanshan Tectonic Belt is situated among the Qilian Orogenic Belt to the southwest, the Alxa Massif to the west and the Ordos Block to the east. The Helanshan Tectonic Belt has received increasing attention since it was argued as the plate boundary separating the Alxa Massif from the Ordos Block, and hence Alxa Massif was isolated from the North China Craton during Triassic. The Middle to Upper Triassic strata in the northwestern Ordos and the Helanshan Tectonic Belt witnessed the tectonic evolutionary processes between the Alxa Massif and the Ordos Basin, hence are pivotal to understand the relationship between the Alxa Massif and the North China Craton. In this work, integrated paleocurrent orientation, gravel component, sandstone modal composition and detrital zircon U–Pb isotopic analyses were applied to trace the source area and reconstruct the source-to-sink relations between the Alxa Massif and Ordos Basin. The southeast orientated paleocurrent directions suggest detritus in the northwestern Ordos were mostly sourced from the northwest. Clastic compositions reveal a mixed orogeny provenance, including magmatic arc and continental block sources. Detrital zircons from four sandstones in the Helanshan Tectonic Belt yields four major LA-ICPMS U-Pb age groups of 2600–2200 Ma, 2000–1700 Ma, 480–400 Ma and 350–200 Ma, suggesting multiple-sourced provenance. Comparing to the magmatic records in the Alxa Massif and the Qilian Orogenic Belt, the Triassic detritus in the Helanshan Tectonic Belt were mainly from the Alxa Massif with additional supplements from the Qilian Orogenic Belt, which finally debouched to the lacustrine in the interior Ordos Basin to the southeast. Triassic basin evolution of the northwestern Ordos was further associated with post-collision in the Alxa Massif after the closure of the Paleo-Asian Ocean. [ABSTRACT FROM AUTHOR]
- Published
- 2019
- Full Text
- View/download PDF
7. Middle–Late Triassic sedimentation in the Helanshan tectonic belt: Constrain on the tectono-sedimentary evolution of the Ordos Basin, North China.
- Author
-
Sun, Jiaopeng and Dong, Yunpeng
- Abstract
Abstract The Helanshan tectonic belt is located to the west of the Ordos Basin, and separates the Alxa (or Yinshan) Massif to the west from the Ordos block to the east. Triassic sedimentation in the Helanshan tectonic belt records important information about tectono-sedimentary process between the Alxa Massif and the Ordos block. Detailed geological mapping and investigation on the lithological package, sedimentary facies and paleocurrent orientation have been conducted on the Middle to Upper Triassic clastic rocks in the Helanshan tectonic belt. The succession is characterized by upward-fining sequence and comprises coarse grained alluvial-fluvial facies in the lower part as well as deltaic-lacustrine facies in the upper part. Based on detailed study and comparisons on the sedimentary sequence along various sections, the Middle to Upper Triassic strata have been revealed that show clear southeastward-deepening sedimentary differentiation and transgression from southwest to northeast, which are consistent with the southeastward flowing paleocurrent. These features indicate a southeastward-dipping paleogeography in the Helanshan tectonic belt, which was original western part of southeastward orientated fluvial-lacustrine system in the northwestern proto-Ordos Basin. Further to the east, the Triassic succession in the Ordos Basin displays gradually thickening and alluvial-fluvial system flowed from southeast to northwest, showing a huge thick sedimentary wedge in the western basin margin. Together with the Late Permian–Early Triassic closure of the Paleo-Asian Ocean to the north, the Late Triassic extensional structures and diabase dykes in the Helanshan tectonic belt, all the above sedimentary features could be mostly interpreted as records of an extensional basin correlated to post-collisional collapse of the Central Asian Orogenic Belt. Graphical abstract Image 1 Highlights • A southeastward deepening paleogeography was formed in the Helanshan Tectonic Belt. • A thick sedimentary wedge thickening toward the basin margin is reconstructed. • Triassic rifting basin evolution was related to post-collisional orogeny collapse. • The Alxa Massif was the westernmost extension of the North China Block in Triassic. [ABSTRACT FROM AUTHOR]
- Published
- 2019
- Full Text
- View/download PDF
8. Ultrahigh‐temperature metamorphism in the Helanshan complex of the Khondalite Belt, North China Craton: Petrology and phase equilibria of spinel‐bearing pelitic granulites.
- Author
-
Gou, Longlong, Li, Zhenghui, Liu, Xiaoming, Dong, Yunpeng, Zhao, Jiao, Zhang, Chengli, Liu, Liang, and Long, Xiaoping
- Subjects
HIGH temperatures ,METAMORPHIC rocks ,PETROLOGY ,GRANULITE ,OROGENIC belts - Abstract
To better understand the formation of ultrahigh‐temperature (UHT) metamorphic rocks, we present a detailed petrological study of the recently discovered spinel‐bearing garnet–sillimanite granulites in the Helanshan complex of the Khondalite Belt in the North China Craton. In calculated P–T pseudosections, isopleths of grossular content in the peak assemblage field of garnet+K‐feldspar+sillimanite+spinel+ilmenite+quartz+melt suggest that the metamorphic peak occurred at ∼960–1,030°C and 6.3–7.3 kbar. Using ternary feldspar thermometry, a minimum temperature limit of the peak metamorphic conditions is calculated to be ∼910–955°C at 6.5 kbar, with a weighted mean of ∼940°C. Thus, all these results point to a very steep geothermal gradient well into the UHT field. In addition, a clockwise P–T evolution is determined, which involves pre‐Tmax decompression followed by nearly isobaric cooling. Based on these newly discovered UHT pelitic granulites, which do not contain index minerals typically considered diagnostic of UHT metamorphism, and the high‐P pelitic granulites exposed in the Helanshan and Qianlishan complexes, we propose that the Khondalite Belt is an ultrahot metamorphic orogen formed by collision between the Yinshan and Ordos Terranes. The style of this continental collision was rather different from Phanerozoic collisions, but was similar to the two‐sided hot collision model during the Proterozoic. Two‐sided hot collision involves shallow slab breakoff during collision, which leads to extension and the development of a wide plateau‐like orogen, which is underlain by melt‐bearing mantle that maintains a hot environment at the collision zone. [ABSTRACT FROM AUTHOR]
- Published
- 2018
- Full Text
- View/download PDF
9. Geochronology and geochemistry of mafic dykes in the Helanshan complex: Implications for Mesozoic tectonics in the North China Craton.
- Author
-
Li, Zhenghui, Liu, Xiaoming, Dong, Yunpeng, Santosh, M., Zhang, Feifei, and Xu, Jie
- Abstract
Abstract The Helanshan tectonic belt (HTB) is a major tectonic divide between the Alxa and Ordos blocks in the North China Craton. The geochronology and petrogenesis of the mafic dykes in the northern HTB are keys to understanding the tectonic evolution of this belt. The mafic dykes, intruded into the Neoarchean–Paleoproterozoic metamorphic basement, are mainly composed of diabase with a mineral assemblage of plagioclase (45%–60%), pyroxene (25%–35%), minor quartz and Fe–Ti oxides. The LA-ICPMS U–Pb analysis of zircon grains from representative dykes yield a weighted mean age of 206 ± 1.9 Ma, which represents the crystallization age of the dyke. The diabases show high contents of Fe 2 O 3
T (11.88–17.55 wt.%), low contents of SiO 2 (45.65–50.95 wt.%) and MgO (3.31–5.50 wt.%) with low Mg# (=100 × MgO/(MgO + FeO) atomic ration) of 33–44. They are characterized by enrichment of light rare earth elements (LREEs) and large ion lithophile elements (LILEs) (e.g., Rb, Ba and Pb), and slight depletion of high field strength elements (HFSEs). These features suggest that the magma has undergone extensive fractionation of olivine and pyroxene but only minor crustal contamination during its evolution. Their high Sm contents and La/Sm ratios, and low Sm/Yb ratios indicate that magma from which the dykes formed was derived from low degree (about 5%) partial melting of an enriched garnet + spinel lherzolite mantle source. Together with regional geology, these geochemical and geochronological data suggest that the mafic dykes in the HTB were formed in an intracontinental extensional setting during the late Triassic. Graphical abstract Image 1 Highlights • Mafic dykes in the Helanshan Mountains have a crystallization age of 206 ± 1.9 Ma. • The dykes were derived from an enriched, lithospheric mantle source. • The dykes were formed in an intracontinental extensional setting in Late Triassic. [ABSTRACT FROM AUTHOR]- Published
- 2018
- Full Text
- View/download PDF
10. Geochronology, geochemistry and Nd–Hf isotopes of the Xiaokouzi granite from the Helanshan complex: Constraints on the Paleoproterozoic evolution of the Khondalite Belt, North China Craton.
- Author
-
Li, Wei, Dong, Yunpeng, and Liu, Xiaoming
- Subjects
- *
GEOCHEMISTRY , *HAFNIUM isotopes , *GRANITE , *PROTEROZOIC Era , *CRYSTALLIZATION - Abstract
Highlights • LA-ICP-MS zircon U-Pb dating yield 2023 ± 11∼2034 ± 14 Ma for the Xiaokouzi granite. • The ∼2.0 Ga magmatic rocks were the potential provenance of the Khondalite Belt. • The khondalite protoliths were most likely deposited on active continental margin. Abstract The Khondalite Belt is one of the three Paleoproterozoic mobile belts in the North China Craton and was formed by a continental collision between the Yinshan and Ordos Blocks at ca. 1.95 Ga. Although the metamorphism, geochemistry and geochronology of the Khondalite Belt have been extensively studied, the provenance and depositional setting of the khondalite protoliths remain controversial. In this study, U–Pb zircon ages and geochemistry of the Xiaokouzi granite in the southern Helanshan Complex, part of the Khondalite Belt, are investigated. Zircon U–Pb dating indicates that the Xiaokouzi granite was formed between 2023 ± 14 Ma and 2034 ± 16 Ma. The granite shows variable SiO 2 (64.33–74.14 wt%), moderate Al 2 O 3 (14.75–17.23 wt%) and A/CNK values (1.09–1.66), low CaO (0.33–2.35 wt%), TiO 2 (0.30–0.66 wt%), TFe 2 O 3 (2.58–5.76 wt%), MgO (0.82–2.32 wt%) and K 2 O (2.57–4.96 wt%) contents. These features indicate that the Xiaokouzi granite is a peraluminous S-type granite. The Xiaokouzi granite has Cr and Ni contents of 32.7–84.5 ppm and 10.7–19.3 ppm, respectively. The granite is enriched in Cs, K, Pb, and Zr, and depleted in Nb, Ta, P, and Ti. The granite displays variable ɛ Nd (t) values (–1.7 to +3.5) with a corresponding two-stage Nd model age of 2.2–2.5 Ga. In addition, the granite has high initial 176Hf/177Hf ratios (0.281569–0.281789) and positive ɛ Hf (t) values (+1.1 to +8.1) with a two-stage Hf model age of 2.2–2.6 Ga suggesting a juvenile source. The crystallization age of the Xiaokouzi granite is synchronous with the peak in the detrital zircon age population from metasedimentary rocks in the Khondalite Belt. In addition, Hf isotope values from the Xiaokouzi granite are consistent with the detrital zircons from metasedimentary rocks. Together with other Paleoproterozoic igneous rocks in the Khondalite Belt, it is inferred that Paleoproterozoic magmatic rocks in the Khondalite belt may be the potential provenance for khondalite protoliths. Combined with previous geological data from the Khondalite Belt, we propose that the Helanshan khondalite protoliths were most likely deposited in an active continental margin near the Ordos Block. [ABSTRACT FROM AUTHOR]
- Published
- 2018
- Full Text
- View/download PDF
11. Pressure–temperature–time (P–T–t) evolution of fore-arc and foreland schist in the Qinling Orogenic Belt, China: Implications for Late Paleozoic and Triassic subduction termination.
- Author
-
Varga, Jan, Kelsey, David E., Dong, Yunpeng, Raimondo, Tom, and Hand, Martin
- Abstract
The Qinling Orogenic Belt (QOB) is a segment of the larger Central China Orogen and marks the amalgamation of the South and North China Cratons during a protracted period spanning the Neoproterozoic through to Triassic. The complex evolution of the QOB has been extensively studied through U–Pb zircon geochronology, but lacks fundamental characterisation of its time-integrated thermal history. Moreover, the comparatively few metamorphic studies that exist focus exclusively on high-pressure rocks at the margins of major tectonic divisions within the QOB. Samples for this study are metapelitic schists sourced from the Qinling Mountains, North Qinling Belt (NQB), deep in the QOB interior. Cordierite schist has metamorphic monazite age affinities to Late Triassic magmatism and metamorphism in the South Qinling Belt (SQB) occurring at 230–220 Ma. Calculated phase equilibria modelling constrains metamorphism to 1.0–2.0 kbar and 530–545 °C, corresponding to a steep apparent thermal gradient between ~275–530 °C/kbar. This probably represents contact metamorphism of the Liuling Group turbidite sequence by intruding magma. Garnet–staurolite schist has metamorphic monazite age data that overlaps with Late Paleozoic events occurring between 420 and 400 Ma. Calculated phase equilibria modelling constrains peak metamorphism to ~7.1 kbar and 615 °C, corresponding to a shallower thermal gradient of ~87 °C/kbar. This represents Barrovian-style metamorphism of fore-arc sedimentary units during arc–continent collision marking the closure of the Shangdan Ocean. Metamorphism of these fore-arc sequences has a comparable thermal gradient to Guishan Complex equivalents in the Tongbai Orogen, which is a continuation of the Qinling Orogen to the east. This study establishes previously undocumented contact metamorphism in the northern SQB and Barrovian-style metamorphism in the NQB, providing key constraints for tectonic models that explain the evolution of the QOB and broader Central China Orogen. [ABSTRACT FROM AUTHOR]
- Published
- 2018
- Full Text
- View/download PDF
12. Mesozoic and Cenozoic multiple deformations in the Helanshan Tectonic Belt, Northern China.
- Author
-
Yang, Xiangyang and Dong, Yunpeng
- Abstract
The Helanshan Tectonic Belt (HTB) is located in the tectonic boundary between the Alxa massif and the Ordos Basin, and witnessed the tectonic processes between the Alxa massif and the Ordos Basin. The deformation structures in the Phanerozoic successions are keys to understanding the multiple phases of deformation along the HTB. Together with regional geology, our new geological mapping and structural analysis reveal that HTB has been formed at least by four phases of deformation during the Mesozoic and Cenozoic times. First phase of deformation (D 1 ) is represented by the WNW-trending open-folds of the Paleozoic and Triassic strata, and formed by NNE-SSW contraction. The angular unconformity between the deformed Paleozoic-Triassic strata and overlying Middle Jurassic strata constrains that D 1 occurred in the Early Jurassic. Second phase of deformation (D 2 ) is indicated by the NE-striking tight-folds of the Triassic and Jurassic strata, and the superimposed deformation on D 1 structures. Geometrical and kinematic analysis suggests that D 2 was constructed by a phase of NW-SE contraction. The angular unconformity between the Middle Jurassic and the Lower Cretaceous strata suggests that D 2 was formed during the Late Jurassic. Third phase of deformation (D 3 ) is characterized by NNE-striking normal faults on both sides of the HTB, which separate the HTB from the Bayanhote basin to the west and Yinchuan graben to the east. D 3 is consistent with the regional NE-trending horst-graben structural system, and correlates to a regional extension in WNW-direction. According to the contact correlation of the Lower Cretaceous deposits and these normal faults, they are indicated as syndepositional faults during the Early Cretaceous. The fourth phase of deformation (D 4 ) was characterized by NW-striking open folds and the NE-trending strike-slip faults in the Eocene strata as well as the older strata. Together with the youngest strata involved into D 4 deformation is the Oligocene, the previous age of 13.4 Ma for the reactivation of the Zongbieli-Zhengyiguan fault constrains the deformation time of D 4 in the Late Miocene. [ABSTRACT FROM AUTHOR]
- Published
- 2018
- Full Text
- View/download PDF
13. Meso-Neoproterozoic proto-basins and oil–gas resources in China: Preface.
- Author
-
Li, Sanzhong, Dong, Yunpeng, and Chen, Hanlin
- Subjects
- *
PETROLEUM , *PETROLEUM prospecting , *GAS reservoirs , *GAS distribution , *NATURAL gas prospecting , *CRATONS - Abstract
• We unravel the tectonic reworking and formation of proto-basins of the North China, Yangtze and Tarim cratons. • We reconstruct the tectonic paleogeography and prototype basin of the three cratons. • We identify the effect of the late superimposed geological events for the proto-type basins and their oil and gas petroleum systems. The recent discovery of Meso-Neoproterozoic primary oil and gas reservoirs within ancient cratonic basins of the world has promoted studies on the mechanism and exploration of these primary reservoirs. The formation and distribution of oil and gas resources are controlled by the tectonic setting, paleogeography, paleo-environment and biological evolutionary history related to supercontinents. The nature and distribution of proto-type basins are a key to oil and gas exploration and evaluation for the Meso-Neoproterozoic basins. This special issue is focused on the theme of "Supercontinental breakup process, basin formation, late deformation, and oil and gas accumulation". It aims to provide a cross section of the interdisciplinary methods adopted to study Meso-Neoproterozoic basin-forming tectonic settings and evolutionary processes in the three cratons of China, to unravel the tectonic reworking and formation of proto-basins, to reconstruct the tectonic paleogeography and prototype basin, and to identify the effect of the late superimposed geological events for the proto-type basins and their oil and gas petroleum systems. [ABSTRACT FROM AUTHOR]
- Published
- 2021
- Full Text
- View/download PDF
14. Timing of two separate granulite-facies metamorphic events in the Helanshan complex, North China Craton: Constraints from monazite and zircon U–Pb dating of pelitic granulites.
- Author
-
Gou, Longlong, Zi, Jian-Wei, Dong, Yunpeng, Liu, Xiaoming, Li, Zhenghui, Xu, Xiaofei, Zhang, Chengli, Liu, Liang, Long, Xiaoping, and Zhao, Yuhang
- Subjects
- *
ZIRCON , *LASER ablation inductively coupled plasma mass spectrometry - Abstract
This study presents the results of monazite and zircon U–Pb dating of garnet–biotite gneiss and recently discovered spinel-bearing ultrahigh-temperature (UHT) pelitic granulites from the Paleoproterozoic Helanshan complex of the North China Craton, and considers implications for the formation of the complex and the tectonic history of this region. SHRIMP monazite U–Pb dating of the garnet–biotite gneiss yielded a weighted mean 207Pb/206Pb age of 1944.4 ± 4.2 Ma, which is the same within error as a weighted mean laser ablation–inductively coupled plasma–mass spectrometry (LA–ICP–MS) 207Pb/206Pb age of 1959 ± 18 Ma obtained from metamorphic zircons within the same unit. The age of 1959 ± 18 Ma is similar to the published metamorphic ages of ca. 1.96–1.95 Ga from high-temperature (T max < 900 °C) pelitic granulites in the Helanshan, which represent the timing of continental collision between the Yinshan and Ordos terranes as suggested by previous published works. Metamorphic monazites from the spinel-bearing UHT pelitic granulite unit in this area yielded weighted mean 207Pb/206Pb ages of 1930.8 ± 2.6 and 1933.6 ± 3.1 Ma, which are consistent with the ages of metamorphic zircons. These ages record the timing of UHT metamorphism within the Helanshan complex and are similar to 1.93–1.92 Ga ages previously reported from typical UHT pelitic granulites within the Jining and Daqingshan complexes of the Khondalite Belt, where ca. 1.92 Ga metamorphic zircons are thought to record the cooling of the UHT rocks to the solidus. The new data presented here indicate that the ca. 1.93 Ga UHT metamorphic event occurred across a wider area than previously thought and extended into the Helanshan complex. Combining these new data with the results of previous research suggests that the entire Khondalite Belt was influenced by a ca. 1.93 Ga UHT metamorphic event that was preceded by metamorphism associated with continental collision between the Yinshan and Ordos terranes at ca. 1.95 Ga. This suggests that the Khondalite Belt underwent a tectonic transition from compression to extension between 1.95 and 1.93 Ga, a process likely controlled by a late-stage shallow slab-breakoff event. • A combined of monazite and zircon U–Pb dating is firstly conducted in the Helanshan. • Two separate granulite-facies metamorphic events at ca. 1.96 Ga and 1.93 Ga. • A tectonic transition from collision to extension during the period of 1.95–1.93 Ga. [ABSTRACT FROM AUTHOR]
- Published
- 2019
- Full Text
- View/download PDF
15. Pressure-temperature-time (P-T-t) evolution of fore-arc and foreland schist in the Qinling Orogenic Belt, China: Implications for Late Paleozoic and Triassic subduction termination
- Author
-
Yunpeng Dong, David E. Kelsey, Martin Hand, Jan Varga, Tom Raimondo, Varga, Jan, Kelsey, David E., Dong, Yunpeng, Raimondo, Tom, and Hand, Martin
- Subjects
geography ,geography.geographical_feature_category ,Subduction ,020209 energy ,Metamorphic rock ,Schist ,Geochemistry ,Metamorphism ,Geology ,central China orogen ,02 engineering and technology ,010502 geochemistry & geophysics ,01 natural sciences ,Craton ,North China craton ,metamorphism ,pseudosection modelling ,Geochronology ,0202 electrical engineering, electronic engineering, information engineering ,monazite ,Foreland basin ,0105 earth and related environmental sciences ,Zircon - Abstract
The Qinling Orogenic Belt (QOB) is a segment of the larger Central China Orogen and marks the amalgamation of the South and North China Cratons during a protracted period spanning the Neoproterozoic through to Triassic. The complex evolution of the QOB has been extensively studied through U–Pb zircon geochronology, but lacks fundamental characterisation of its time-integrated thermal history. Moreover, the comparatively few metamorphic studies that exist focus exclusively on high-pressure rocks at the margins of major tectonic divisions within the QOB. Samples for this study are metapelitic schists sourced from the Qinling Mountains, North Qinling Belt (NQB), deep in the QOB interior. Cordierite schist has metamorphic monazite age affinities to Late Triassic magmatism and metamorphism in the South Qinling Belt (SQB) occurring at 230–220 Ma. Calculated phase equilibria modelling constrains metamorphism to 1.0–2.0 kbar and 530–545 °C, corresponding to a steep apparent thermal gradient between ~275–530 °C/kbar. This probably represents contact metamorphism of the Liuling Group turbidite sequence by intruding magma. Garnet–staurolite schist has metamorphic monazite age data that overlaps with Late Paleozoic events occurring between 420 and 400 Ma. Calculated phase equilibria modelling constrains peak metamorphism to ~7.1 kbar and 615 °C, corresponding to a shallower thermal gradient of ~87 °C/kbar. This represents Barrovian-style metamorphism of fore-arc sedimentary units during arc–continent collision marking the closure of the Shangdan Ocean. Metamorphism of these fore-arc sequences has a comparable thermal gradient to Guishan Complex equivalents in the Tongbai Orogen, which is a continuation of the Qinling Orogen to the east. This study establishes previously undocumented contact metamorphism in the northern SQB and Barrovian-style metamorphism in the NQB, providing key constraints for tectonic models that explain the evolution of the QOB and broader Central China Orogen Refereed/Peer-reviewed
- Published
- 2018
Catalog
Discovery Service for Jio Institute Digital Library
For full access to our library's resources, please sign in.