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In geological history, volcanism is closely related to the deposition of many black shales. However, the specific mechanism between volcanism and the deposition of black shales is still unclear. The black shales developed in the Chang 7 Member of the Yanchang Formation in the Ordos Basin are considered the most important hydrocarbon source rocks in Central China. The shales are deposited by frequent volcanic activities and preserved by extremely rich volcanic ash layers, making them an excellent example when investigating the influence of volcanism on the deposition of black shales. In this paper, petrographic, mineralogical, and geochemical analyses of three typical tuff and black shale segments of the Chang 7 Member were carried out. The productivity indicators [total organic carbon (TOC), P/Al, Ni/Al, and Cu/Al], redox indicators (V/Al, Mo/Al, U/Al and U/Th), and clastic influx indicators (Ti/Al and ƩREE) of the shales basically increased together in the longitudinal direction, and a relatively good positive correlation existed between P/Al, Ni/Al, Cu/Al, V/Al, Mo/Al, U/Al, U/Th, Ti/Al, ƩREE, and TOC. This finding indicated that the development of the Chang 7 black shales is the result of a combination of high primary productivity, anoxic conditions, and increased clastic influx. Considering that increased clastic influx may dilute organic matter, many phosphate nodules represented high productivity above the volcanic ash layers, and anoxic conditions are likely to be the result of a large amount of organic matter degradation indicated by the covariations of TOC versus P/Al and TOC versus Ba/Al. Therefore, the Chang 7 black shales in this study may be mainly controlled by the increased primary productivity. In addition, compared with the Weathering Index of Parker of background shales (not the contact clip or tuff layer), that of the black shales was significantly reduced after tuff deposition. On the contrary, the clastic influx indicators, redox indicators, productivity indicators of black shales significantly increased. This finding suggested that a series of environmental effects, such as enhanced weathering of terrestrial sources, increased clastic influx, anoxic water, and productivity bloom, was likely caused by volcanic activity. Considering that hydrothermal activity at the same time as volcanism may not cause productivity bloom, the nutrients (P/Al and Fe/Al) of the Chang 7 tuffs were significantly depleted, and the total sulfur content of black shales was much higher than that in ordinary freshwater sedimentation. Therefore, this paper reviewed and proposed the volcanism hypothesis model of the Chang 7 black shales. Volcanism generates large amounts of SO2 and volcanic ash. SO2 forms large areas of acid rain and accelerates terrigenous weathering with an increase in the lake land-based sources of debris and nutrient supply, while volcanic ash is decomposed and releases nutrients. These phenomena lead to biological productivity bloom and massive accumulation of organic matter, which in turn results in lake water anoxia and the eventual formation of black shales. [ABSTRACT FROM AUTHOR]

This paper aims to analyze the deformation characteristics and constrain the deformation time of the Gudonghe ductile shear belt in the Yanbian area, NE China, the eastern segment of the Central Asian Orogenic Belt. Two stages of ductile deformation have been identified according to the macro- and micro-fabric characteristics. The NWW-trending D1 deformation, with pervasive dextral shearing and extensional features as indicated by shear folds and δ-porphyroclasts, occurred in the Early–Middle Triassic Yongxin pluton based on zircon U–Pb age of 246–236 Ma and previously published geochronological data, and the foliation was cut by an undeformed igneous rock of ~ 226 Ma; therefore, the D1 deformation time in the Gudonghe ductile shear belt is limited to the 236–226 Ma. The NE-trending D2 deformation event occurred in the Early Jurassic Baijin pluton. The S–C fabrics and σ-porphyroclasts in the D2 deformation stage show a pervasive sinistral shearing and were formed in a compression setting. Two deformed granites in the D2 deformation stage have a weighted mean age of 197 Ma, while the syn-tectonic granitic vein during the D2 deformation stage has a weighted mean age of 184 Ma. The undeformed granites, which intruded into the Early Jurassic Baijin pluton, have a weighted mean age of 179 Ma. Therefore, the D2 deformation of the Gudonghe ductile shear belt occurred during 184–179 Ma. Considering the regional tectonic evolution and the structural features of the Gudonghe ductile shear belt, the D1 deformation event could be related to the Middle–Late Triassic post-orogenic collapse after the closure of the Paleo-Asian Ocean, while the D2 deformation was formed in a compressional setting and was related to the onset of westward-directed subduction and accretion of the Paleo-Pacific Ocean in the Early Jurassic. [ABSTRACT FROM AUTHOR]

Permian magmatism occurred widely in the Tarim basin and adjacent areas of NW China, resulting in the emplacement of numerous carbonatite plutons and alkaline rock intrusions, which are likely to have been derived from mantle sources. In addition, at least one large igneous province (LIP) can be recognized in NW China; namely, the ca. 270–290 Ma Tarim LIP, and it can be inferred that the peak age of magma activity is ~ 280 Ma. Therefore, the mantle plume is limited spatially within southern Tianshan and the Tarim Basin and temporally in the Early Permian. Age and field evidence suggest a spatial and temporal relationship between the carbonatites and alkaline rocks within the Tarim LIP, and their genesis is related to the Tarim mantle plume. In this paper, we direct our attention to the mineral assemblages that are related to carbonatites and alkaline rocks which host REE deposits (Wajilitag, Boziguoer) in the northern Tarim Craton. Alkaline rocks typically are related to rifts and/or extensional tectonics, and we suggest that these magmatic and metallogenic events occurred during an extensional regime, possibly related to the Tarim mantle plume event that affected much of South Tianshan during the Permian. [ABSTRACT FROM AUTHOR]

The mechanics of crustal growth in the Altaids during the Phanerozoic is still not well understood. This paper reports new geochronological, geochemical, and isotopic data from Paleozoic adakitic intrusions in the Dananhu arc in the Chinese Eastern Tianshan with the aim of better understanding the specific mechanisms of crustal growth. Our new LA-ICPMS U–Pb zircon age data show that four phases of adakitic intrusions formed at 410–413 Ma, 385–387 Ma, 335 Ma, and 313–311 Ma. Combined with previous data of ours and from the literature, there were seven phases of adakitic intrusions from the Silurian to early Permian. All these adakitic intrusions have distinctive geochemical-isotopic signatures with high Na and Al, high Sr, low Yb and Y, high Sr/Y and (La/Yb)N values, relatively high MgO contents and Mg numbers (Mg# = 41–70), high abundances of compatible elements (Cr = 1.66–46.30 ppm, Ni = 2.40–26.96 ppm), and positive high εHf (t) (+ 7.1 to + 15.6) and a TDM (Ma) range from 325 to 670 Ma. These adakitic intrusions were associated with essential Cu polymetallic mineralization in the Dananhu arc. The above chemical data and relations indicate that the processes of oceanic slab melting generated these adakitic rocks. Our new geochronological, geochemical and isotopic data, integrated with the geology of the Dananhu intra-oceanic arc, lead us to conclude that multiphase of hot/young oceanic crust subduction and melting generated the massive crustal growth in the Silurian–early Permian. Our results indicate that the magmas were derived by slab melting of hot/young oceanic crust, which was one of the most critical mechanisms of continental crustal growth in the Paleozoic accretionary orogen of the Altaids. [ABSTRACT FROM AUTHOR]

The lacustrine source rocks of the upper member of the lower Ganchaigou Formation ( E 3 2 ) in the Yingxi area are considered to be important source rocks in the Qaidam Basin in northwestern China. In this study, we investigated the organic geochemical characteristics of the source rocks by selecting representative samples of the Eocene lacustrine succession spanning 200 m. The results show that the source rock quality is at a fair to good level, and the organic matter (OM) is in the immature–low-maturity stage. The OM originated from plankton/algae and bacteria, with a fluctuating input of terrigenous plants. The source rocks were deposited in a reducing saline-hypersaline environment, with water-column stratification associated with a variable chemocline related to a fluctuating salinity. The vertical variability of the OM abundance is accompanied by simultaneous changes in the source of the OM and the lake water environment parameters, which is caused by the oscillations between drier and wetter conditions in inland Asia in the Late Eocene. The drier periods had strong evaporation and low fluvial input, which facilitated the formation of widespread water anoxia and enhanced OM preservation, while the wetter periods had higher fluvial input and moderate OM preservation conditions because the higher sedimentation rate led to a strong terrestrial dilution effect, which in turn limited the accumulation of OM. [ABSTRACT FROM AUTHOR]

Eastern Tianshan is an important nickel ore belt in China, in which large to middle-sized magmatic Ni–Cu sulfide deposits occur spatially in the eastern part. The Baixintan magmatic Ni–Cu sulfide deposit is an important discovery in the western part of Eastern Tianshan, which provides an ideal target to track the evolution of the magmatic mineralization system in this part. The Baixintan intrusion is composed of the northeastern mafic units and the southwestern mafic–ultramafic units. The olivine Fo contents of the Baixintan intrusion range from 81.12 to 84.46 mol.%. Numerical calculations yield a parental magma composition with 9.14 wt.% MgO. The Rayleigh simulation using olivine Fo and Ni contents shows that the parental magma of the Baixintan intrusion has experienced ~ 2% olivine crystallization, and then evolved magma became sulfide-saturated. Calculations by the mass-balance R factor equation using PGE data indicate that the formation of the mafic and mafic–ultramafic units of the Baixintan intrusion resulted from multiple influxes of magmas. The Baixintan intrusion is highly comparable with those mafic–ultramafic intrusions that host large magmatic Ni–Cu sulfide deposits in the eastern part of Eastern Tianshan. The mafic–ultramafic intrusions in the western part of Eastern Tianshan should be carefully evaluated for the potential of hosting large magmatic Ni–Cu deposits. [ABSTRACT FROM AUTHOR]

The final closure of oceans in accretionary orogens is a transformative process for continental crustal growth. The geodynamic mechanism is still controversial. This study synthesizes the Permo-Carboniferous tectono-stratigraphy, detrital zircon U–Pb dating and magmatism in the Junggar terranes to determine their interlinkage during ocean closure. The tectono-stratigraphy shows a transition from a late Mississippian regressive to an early Pennsylvanian transgressive and late Pennsylvanian transgressive–regressive sequences controlled by the basin-bounding transtensional faults. Detrital zircon U–Pb chronology displays a change of the provenance area from distant in the late Mississippian to more proximal in the Pennsylvanian. The magmatism indicates that the late Mississippian island-arc volcanic successions, related to subduction, progressively gave way to early Pennsylvanian magmatic activity indicative of regional asthenosphere upwelling, which suggests back-arc basins opened since ~ 319 Ma. The termination of the subduction is constrained by A-type granite plutons (~ 307 Ma). The Junggar terranes changed from an active back-arc basin behind an active subduction zone (319–307 Ma), to a post-subduction back-arc basin that continued to extend in 307–290 Ma. This back-arc basin extension is synchronous with voluminous Pennsylvanian–early Permian granite emplacement in both West Junggar and East Junggar blocks. Asthenospheric upwelling in the back-arc area was triggered by subduction, but continued after subduction had ceased. Transfer of juvenile magma to the crust was enhanced by crustal thinning, high thermal gradient, decompression melting and magma pathways along strike-slip faults. The prolonged back-arc setting provided a mechanism for rapid continental crust generation in the Paleozoic southwestern part of Central Asian Orogenic Belt. [ABSTRACT FROM AUTHOR]

The Luobei Complex in Northeast (NE) China lies in the northern Heilongjiang Complex and comprises a sequence of low-temperature–high-pressure metamorphic rocks distributed along the N–S-oriented suture zone between the Jiamusi and Songliao blocks. However, the timing of formation and tectonic setting of the Luobei Complex remain poorly constrained. Here, we present petrological, geochronological, and geochemical data for metasedimentary rocks from the Luobei Complex to elucidate its origin and tectonic setting. The Luobei Complex is characterised by the occurrence of serpentinite, blueschist, greenschist, amphibolite, and marble, which form lenses or interlayers in a matrix of two-mica schist, albite schist, quartz schist, and granitic gneiss. Zircon U–Pb dating of four metasedimentary rocks yields consistent Late Triassic maximum depositional ages (ca. 214 Ma). Detrital zircons from the Luobei Complex yield ages ranging from 1889 to 202 Ma, with age peaks at 504, 350, 265, and 214 Ma. The ages prior to 350 Ma exist in both the Jiamusi Block and the Central Asia Orogenic Belt (CAOB), indicating that the syn-deposition of Luobei Complex, meanwhile, the lack of ages younger than 350 Ma suggests that the Jiamusi Block rifted eastward from the CAOB. Geochemical data indicate that the studied metasedimentary rocks were formed in a continental island arc setting. These results, together with the Early Jurassic metamorphism reported by previous studies, constrain the timing of final collision to Late Triassic–Early Jurassic after subduction of the Jiamusi Block beneath the Songliao Block. Combining our new results with previous findings, we propose a new tectonic model: (1) during the latest Carboniferous to Late Triassic, the Jiamusi Block rifted from the CAOB as a result of Mongol–Okhotsk oceanic plate subduction; and (2) during the Late Triassic and Early Jurassic, the Jiamusi Block was reunited with the Songliao Block, and the Heilongjiang Complex formed, as a result of Paleo-Pacific plate subduction. [ABSTRACT FROM AUTHOR]

Although China is well-endowed with tungsten deposits, while the tungsten resources in the Central Asian Orogen Belt (CAOB) are rarely reported. Recently, many W-skarn deposits have been discovered in the East Tianshan, but the source and evolution of the mineralising fluids are poorly understood. The Xiaobaishitou W(–Mo) deposits are hosted by carbonaceous limestone or banded crystalline limestone in the Mesoproterozoic Jianshanzi Formation, which is intruded by Triassic biotite monzogranite. The deposit comprises garnet-dominated prograde skarn and retrograde skarns followed by oxides (scheelite–cassiterite–magnetite), sulphides (quartz–molybdenite–bismuthinite–pyrite–chalcopyrite–sphalerite–galena), and carbonate stages. The types of fluid inclusions are composed of liquid-rich aqueous, vapour-rich aqueous, aqueous carbon-dioxide, and daughter mineral-bearing inclusions. The homogenization temperatures of fluid inclusions change from > 400 °C in garnet, through > 380 °C in epidote and 310–280 °C in scheelite, to 280 °C in quartz and 220 °C in calcite indicating a complex magmatic-hydrothermal process. The δ18Owater values varied from + 6.1 to + 8.4‰ in garnet, + 5.2 to + 7.4‰ in epidote, + 2.0 to + 3.0‰ in quartz, to − 0.7 to − 0.1‰ in calcite. The corresponding δD values are − 95 to − 71‰ in garnet, − 84 to − 80‰ in epidote, − 115 to − 90‰ in quartz and − 101 to − 89‰ in calcite. Both O and H isotopic compositions show the mineralisation fluids are originated from deep-sourced magmatic fluids. The δ13CCO2 values in the calcite range from − 7.8 to − 7.7‰, which is characteristic of magmatic fluids interacting with reduced carbon from metamorphic rocks. The δ34S values of hydrothermal fluids range from + 4.5 to + 5.1‰, and 206Pb/204Pb, 207Pb/204Pb and 208Pb/204Pb ratios of sulphide are 18.072–18.664, 15.566–15.708, and 38.245–38.658, respectively, representing a mixed characteristic of magmatic and sedimentary sulphur. Considering the coexisting of L-type and V-type inclusions in the scheelite, we proposed that pH increase caused by fluid boiling may be the major cause for the precipitation of scheelite at the Xiaobaishitou deposit. [ABSTRACT FROM AUTHOR]

The Huangtan (including Jinling) Au–Cu–Zn deposit is an auriferous volcanogenic massive sulfide (VMS) deposit discovered in East Tianshan, Central Asian Orogenic Belt. The deposit is hosted in volcanic breccia and tuff of the Silurian Hongliuxia Formation. The ore bodies consist of concordant massive sulfide lenses and discordant sulfide veins. Chalcopyrite Re–Os dating constrained the age of mineralization in the Huangtan deposit at 432 Ma. Quartz and barite host abundant liquid-rich, liquid-only and minor vapor-rich aqueous fluid inclusions. The fluid inclusions in barite from the exhalative–sedimentary units mainly have homogenization temperatures at 140–260 °C, and calculated salinities of 3–9 wt% NaCl equiv.; Those values are at 120–300 °C, and 1–9 wt% NaCl equiv. for varieties in quartz from the vein ores and alteration assemblages. Fluid inclusions extract from pyrite have 3He/4He ratios of 0.929–1.374 Ra, 40Ar/36Ar of 388–520, and 40Ar/4He of 0.355–0.836. The quartz and barite yielded δ18O values of 7.4‰ to 10.1‰ and the δDV-SMOW values of the fluid inclusions in the quartz and barite range from − 69 to − 42‰. The He–Ar and H–O isotopes imply that the ore-forming fluids were derived from a magmatic source with the addition of deeply circulating seawater. The δ34SV-CDT values of pyrite and chalcopyrite range from − 2.0 to 1.5‰, and those of barite samples range from 24.1 to 24.8‰, which indicates that sulfur was derived from magmatic sulfur, and was subjected to fractionation between sulfide and sulfate. Linked to the ore geology, geochronology data, isotope compositions and fluid inclusions obtained in this study with those of previously published adjacent VMS deposits in the Kalatag area suggest that the Huangtan deposit and adjacent VMS deposits formed in the same metallogenic system. [ABSTRACT FROM AUTHOR]

As a portion of the Central Asian Orogenic Belt (CAOB), the Beishan Orogen is key to the evolution of the Paleo-Asian Ocean (PAO). The Mazongshan ophiolitic mélange in central Beishan Orogen comprises peridotite, gabbro, dolerite, anorthosite, massive and pillow basalt, and chert and turbiditic mudstone. Its age and tectonic environment remain controversial, which seriously affects the understanding of the tectonic evolution of the CAOB and PAO. Geochemical results demonstrated that gabbros could be divided into two distinct groups. Group A was enriched in both large ion lithophile elements (LILE) and high field strength elements (HFSE) and had high total rare earth element (REE) concentrations with the light REE (LREE) distinctly enriched relative to heavy REE (HREE), showing geochemical characteristics of oceanic island basalt (OIB). Group B has enriched LILE but flat HFSE patterns with LREEs slightly depleted relative to HREEs, which was similar to the patterns of normal mid-ocean ridge basalt (N-MORB). Basalts and peridotites displayed consistent geochemistry of MORB. Negative εSr(t) (− 44.89 to − 33.45) and positive εNd(t) (2.21 to 3.29) values of Group A indicated mantle origin. Gabbro and dolerite from Group A yielded a U–Pb age of 420 ± 2 Ma and 414 ± 3 Ma, respectively, but gabbro from Group B and tuff yielded a U–Pb age of 486 ± 15 Ma and 425 ± 6 Ma. The anorthosite dykes were formed approximately during 370 ± 5 Ma. These results demonstrate that the Mazongshan ophiolite represents relicts of the Ordovician–Devonian Paleo-Asian oceanic crust formed in the mid-ocean ridge and oceanic plateau environments. [ABSTRACT FROM AUTHOR]

The Manzhouli–Xin Barag Right Banner area, located in the southwestern Erguna Massif, is characterized by the distribution of a large volume of Mesozoic volcanic rocks and many polymetallic deposits. However, the tectonic setting of this area during the Late Mesozoic remains controversial. In this study, zircon U–Pb ages range from 142.8 ± 1.8 to 140.4 ± 1.6 Ma for the alkali basalt from the Meiletu Formation and 140 ± 0.9 Ma for alkaline rhyolites from the Baiyingaolao Formation, forming a bimodal volcanic rock assemblage. The initial 87Sr/86Sr ratios range from 0.705365 to 0.705674, and the εNd(t) values vary from + 0.55 to + 1.47. The alkaline rhyolites show εHf(t) values ranging from + 5.3 to + 8.6, corresponding to TDM1 and TDM2 ages in the range of 0.48–0.58 Ga and 0.64–0.86 Ga, respectively. Combined with the major and trace element compositions, the Meiletu alkali basalts are characterized by Nb enrichment (averaging 23.6 ppm) and were derived from partial melting of metasomatized subcontinental lithospheric mantle and underwent moderate fractional crystallization of minerals (e.g. olivine, clinopyroxene, apatite, and plagioclase). The alkaline rhyolites show A1-type granite affinity and originated from partial melting of the mafic lower crust accompanied by fractional crystallization. This suite of bimodal volcanic rocks was mainly dominated by the Mongol–Okhotsk tectonic regime, and the Erguna Massif was in a back-arc extensional setting triggered by slab rollback during the Early Cretaceous. [ABSTRACT FROM AUTHOR]

The Archean Kongling tonalite–trondhjemite–granodiorite (TTG) rocks and Neoproterozoic Huangling granodiorite–monzogranite–tonalite complex occupy the core of the Huangling anticline of the northern Yangtze Craton, South China. These Precambrian felsic rocks have provided crucial clues for understanding the earliest crustal growth in South China. This study presents a set of new zircon U–Pb geochronological and Lu–Hf isotopic data, and whole-rock geochemical data for the mafic dykes, predominantly intruding the Kongling TTG package in the northern Huangling anticline. Our data show that the dykes might be geochemically subdivided into Groups 1 and 2. Group 1 is characterized by low Al2O3, Na2O + K2O, Mg#, Th/Ta, and Sm/Yb but high FeOt and TiO2. In contrast, the Group 2 samples are marked by higher Al2O3, Mg#, Th/Ta, and Sm/Yb but lower FeOt and TiO2. The Group 1 dykes are inferred to be of Paleoproterozoic origin. Group 2 has zircon U–Pb ages of ~ 800 Ma but distinct εHf(t) values among the rock samples, ranging from − 0.3 to − 31.5 and indicating the Neoproterozoic lithospheric mantle being heterogeneous. The Paleoproterozoic Group 1 mafic dykes originated from an enriched and dry lithospheric source. The Neoproterozoic Group 2 mafic dykes were generated by an enriched lithosphere that was modified by slab-released fluid. In addition, a tonalite sample from the southern Huangling anticline is dated at ~ 815 Ma, and has the εHf(t) values ranging from − 19.8 to + 6.9. The wide εHf(t) range suggests the mixing between an enriched lithosphere with a less enriched source. Our data, along with the coeval mafic rocks in NW South China, North Laurentia, and South Australia, indicate that the Neoproterozoic mafic dykes and tonalite in the Yangtze interior are most likely the products in the supra-subduction setting along the Rodinia margin. [ABSTRACT FROM AUTHOR]

Many silicic plutonic rocks of the Late Permian Emeishan large igneous province (ELIP) are spatially and temporally related to oxide ore-bearing layered mafic–ultramafic intrusions. Their association suggests that there may be a petrogenetic link between the two rock types where the layered intrusion represents the cumulate portion of the magma system and the silicic rocks are the residual liquid portion. An alkali feldspar syenite collected in close spatial association with the Hongge-layered mafic–ultramafic intrusion yielded a weighted-mean zircon U–Pb age of 261.5 ± 2.4 Ma with a corresponding weighted-mean εHf(t) value of + 6.5 ± 0.5. The Hongge syenite is alkalic, metaluminous, and ferroan and somewhat similar to other A-type granitoids of the ELIP but, it is composed of ~ 90 vol% alkali feldspar. The rocks have initial 87Sr/86Sr ratios of 0.70570 and 0.70515 and εNd(t) values of − 0.3 and + 1.4. Rhyolite-MELTS and isotopic modeling indicate that the Hongge syenite is likely produced by crystal accumulation of a residual silicic liquid derived from a mafic parental magma that experienced localized crustal contamination during emplacement. Moreover, the age, location, and composition of the Hongge syenite suggests that it is the uppermost portion of the Hongge-layered intrusion and is representative of the residual silicic liquid of the mafic magmas that form the plagioclase-rich cumulate gabbros of the upper zone. [ABSTRACT FROM AUTHOR]

Recent breakthroughs in petroleum exploration suggest that the Linhe depression in the Hetao Basin in central and western Inner Mongolia has undergone multi-stage Meso-Cenozoic tectonic events and possesses considerable exploration potential. However, structural deformation sequences and the genesis of oil-bearing structures in the basin are still poorly understood. Analyzing the deformation sequences of structural styles can improve the understanding of the basin history and regional tectonic evolution, and is essential for targeting potential traps. In this study, we interpreted 2D seismic profiles, drilling, and well-logging data, and outcrops to elucidate structural styles, tectonic evolution, and temporal distribution characteristics of styles with the assessment of potential petroleum traps in the Linhe Depression, Hetao Basin. We identified four structural styles and sequences with fault associations in the Linhe Depression, namely, NE-striking normal faults (D1), inversion fault-folds (D2), NE-NNE-striking dextral strike-slip faults and normal faults (D3), and near-E-W-striking sinistral strike-slip faults (D4). Analysis of syn-sedimentary normal faults and the cross-cutting relationship of faults and sedimentary strata indicate that D1, D2, D3, and D4 occurred during the Early Cretaceous, Late Cretaceous to Early Eocene, Middle Eocene to Neogene, and Quaternary, respectively. The temporal development of structural styles promoted the formation, re-construction, and finalization of structural traps, while fault geometry and fluid potential influenced the dominant petroleum migration directions. It is shown that the hydrocarbon generally migrated from the northwestern sag to the southeastern slope during the peak hydrocarbon expulsion period in the Neogene. Traps of inversion anticlines and numerous fault blocks developed in the Cretaceous and Paleogene strata are identified as the most favorable trap types. The traps on the slope were produced by numerous NNE-NE-striking faults, and the dominant migration direction implies that hydrocarbons were available to fill the traps. [ABSTRACT FROM AUTHOR]