Palaeoclimate of the Paleogene Dongying Formation in Bozhong Sag of Bohai Bay Basin

Zhang, Juan; Wang, Chenchen; Wang, Jingmin; wang, Linbo; Jia, Yunqian; Hu, Ruilin

doi:10.1016/j.ptlrs.2021.04.002

Cited by 3 publications

(2 citation statements)

References 10 publications

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“…The shale has a higher abundance of Quercoidites sporopollenin and a lower abundance of Ulmipollenites sporopollenin than the mudstone (Figure 3). Since Quercoidites and Ulmipollenites represent subtropical climates and subtropical-temperate transition climates, respectively (Zhang et al, 2021), these findings indicate that the shale was deposited in a warmer climate than was the mudstone. Furthermore, Ephedripites, a typical xerophyte pollen, regularly occurs in the mudstone samples, while Fupingopollenites, representing humid climates, only occurs in the shale samples.…”

Section: Depositional Environmentsmentioning

confidence: 92%

The influences of sedimentary environments on organic matter enrichment in fine-grained rocks of the Paleogene Shahejie formation in Nanpu Sag, Huanghua Depression, Bohai Bay Basin

Pang

Liu

Chen

et al. 2021

Energy Exploration & Exploitation

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The fine-grained rocks in the Paleogene Shahejie Formation in Nanpu Sag, Huanghua Depression, Bohai Bay Basin, are extremely important source rocks. These Paleogene rocks are mainly subdivided into organic-rich black shale and gray mudstone. The average total organic carbon contents of the shale and mudstone are 11.5 wt.% and 8.4 wt.%, respectively. The average hydrocarbon (HC)-generating potentials (which is equal to the sum of free hydrocarbons (S1) and potential hydrocarbons (S2)) of the shale and mudstone are 39.3 mg HC/g rock and 28.5 mg HC/g rock, respectively, with mean vitrinite reflectance values of 0.82% and 0.81%, respectively. The higher abundance of organic matter in the shale than in the mudstone is due mainly to paleoenvironmental differences. The chemical index of alteration values and Na/Al ratios reveal a warm and humid climate during shale deposition and a cold and dry climate during mudstone deposition. The biologically derived Ba and Ba/Al ratios indicate high productivity in both the shale and mudstone, with relatively low productivity in the shale. The shale formed in fresh to brackish water, whereas the mudstone was deposited in fresh water, with the former having a higher salinity. Compared with the shale, the mudstone underwent higher detrital input, exhibiting higher Si/Al and Ti/Al ratios. Shale deposition was more dysoxic than mudstone deposition. The organic matter enrichment of the shale sediments was controlled mainly by reducing conditions followed by moderate-to-high productivity, which was promoted by a warm and humid climate and salinity stratification. The organic matter enrichment of the mudstone was less than that of the shale and was controlled by relatively oxic conditions.

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Section: Depositional Environmentsmentioning

confidence: 92%

The influences of sedimentary environments on organic matter enrichment in fine-grained rocks of the Paleogene Shahejie formation in Nanpu Sag, Huanghua Depression, Bohai Bay Basin

Pang

Liu

Chen

et al. 2021

Energy Exploration & Exploitation

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“…The Cenozoic evolutionary process in this basin needs to be further clarified. Some studies report that the initial time of strike‐slip motion occurred from the Palaeocene to the Early Eocene (Zhang, 2012; Zheng, 2011) or from the Middle to Late Eocene (Hsiao et al, 2004; Huang et al, 2012, 2015, 2018; Mao et al, 2019; Jia et al, 2021; Zhang et al, 2014), while others assert that the transition occurred at the end of the Eocene (Zhang, 2012) or in the Oligocene (Tong et al, 2008). While the mechanism of right‐lateral strike‐slip during the Cenozoic is still controversial, some studies argue that extension and right‐lateral motion are the results of the subduction of the Pacific Plate (Chen et al, 2022; Hsiao et al, 2004), while others state that right‐lateral strike‐slip motion is related to the collision of the Indian and Eurasian Plates (Chen et al, 2022; Wang, Li, et al, 2020).…”

Section: Introductionmentioning

confidence: 99%

Cenozoic evolution and deformation in the Eastern and Western Depression of the Liaohe Subbasin, Bohai Bay Basin: Insights from seismic data

et al. 2023

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In rift basins with multiphase extension, the reactivation of pre‐existing faults plays an important role in the evolution and partitioning of deformation. The Liaohe Subbasin is located in the northeastern Bohai Bay Basin, and the Tanlu Fault Zone (TLFZ) runs through it and experienced extension and right‐lateral strike‐slip during the Cenozoic. Therefore, it is an ideal region for studying the deformation and evolution of rift basins. Based on 3D seismic data, we document the structure and fault characteristics of the Eastern and Western Depressions of the Liaohe Subbasin, identify periods of activity on normal and strike‐slip faults, and analyse the evolution and mechanisms of the Cenozoic evolution of this subbasin. Our main results show that (1) the main faults in the Western Depression exhibited extensional motion throughout the Palaeocene, while the Eastern Depression exhibited significant right‐lateral motion during the Oligocene following the early extension stage. (2) The Cenozoic evolution of the Liaohe Subbasin can be divided into four stages: (i) an initial extension stage (the Palaeocene to the Eocene), (ii) an extension stage with initial strike‐slip (Early Oligocene), (iii) a right‐lateral strike‐slip stage (Late Oligocene) and (iv) a postrift stage (after the Neogene). (3) The upwelling of mantle material caused by the subduction and rollback of the Pacific Plate led to the extension of the Liaohe Subbasin from the Palaeocene to the Eocene. The TLFZ began right‐lateral motion at 40 Ma and experienced strong right‐lateral deformation when rifting was weak in the Oligocene and enhanced deformation after 12 Ma. (4) In this multiphase rifting process, under moderate obliquity, strike‐slip deformation is obvious in the areas close to pre‐existing faults, while extensional deformation is obvious in areas farther away. (5) Cenozoic extension and strike‐slip deformation due to partitioning of strain are caused by obliquely reactivation of TLFZ. This study suggests that the reactivation of pre‐existing strike‐slip faults plays a major role in evolution and strain partitioning. Moreover, the results will contribute to future hydrocarbon exploration in multiphase rift basins.

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Identification of lithofacies and prediction of mineral composition in shales – A case study of the Shahejie Formation in the Bozhong Sag

Cui

Yang

et al. 2022

Unconventional Resources

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Palaeoclimate of the Paleogene Dongying Formation in Bozhong Sag of Bohai Bay Basin

Cited by 3 publications

References 10 publications

The influences of sedimentary environments on organic matter enrichment in fine-grained rocks of the Paleogene Shahejie formation in Nanpu Sag, Huanghua Depression, Bohai Bay Basin

The influences of sedimentary environments on organic matter enrichment in fine-grained rocks of the Paleogene Shahejie formation in Nanpu Sag, Huanghua Depression, Bohai Bay Basin

Cenozoic evolution and deformation in the Eastern and Western Depression of the Liaohe Subbasin, Bohai Bay Basin: Insights from seismic data

Identification of lithofacies and prediction of mineral composition in shales – A case study of the Shahejie Formation in the Bozhong Sag

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