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DOI	10.1080/00206814.2023.2167127
	Sea level changes and sequence stratigraphy of the Lower-Middle Jurassic Quse and Sewa formations in the Qiangtang Basin, central Tibet: Geochemical and palynological perspectives
	Mansour, Ahmed; Xia, Guoqing; Fu, Xiugen; Wang, Jian
发表日期	2023
ISSN	0020-6814
EISSN	1938-2839
起始页码	2879
结束页码	2899
卷号	65 期号:18
英文摘要	Sequence stratigraphy is a commonly used approach to understand basin-fill history and the occurrence of conventional reservoir and/or probable source rocks. Reconstructing a sequence stratigraphic framework in carbonates, marls, and organic-rich mudstones is challenging due to environmental, petrophysical, and sedimentological variations that can be subtle, whereas seismic data may be lacking or of limited use. For this reason, incorporation between palynological analysis and chemostratigraphic profiles is becoming increasingly common to facilitate sequence stratigraphic reconstruction. This study investigates the Quse (lower Toarcian) and Sewa formations (upper Bajocian-Bathonian) in the Bilong Co section from the Qiangtang Basin of central Tibet. Eighty-three rock samples were analysed for their whole-rock inorganic geochemical composition, of which 25 rock samples were tested for palynological and palynofacies analyses. The palynological composition defined two associations for the study section. The lower part of the Bilong Co section consisted is dominated by a moderate to high abundance of opaque phytoclasts versus low to moderate amorphous organic matter (AOM) content with a high concentration of sphaeromorphs pollen grains, revealing deposition of this interval at times of low relative sea level in fluvio-deltaic settings. The middle to upper parts of the section comprised of significantly high AOM content versus low phytoclasts and high content of sphaeromorphs pollen grains, but with increasing the relative abundance of dinoflagellate cysts, indicating a phase of high sea level. Chemostratigraphic variations relevant to changes in relative sea level delineated the subdivision of the Quse and Sewa formations into two and three third-order transgressive-regressive sequences, respectively. The collision between the Lhasa and Qiangtang blocks during the Early-Middle Jurassic is suggested to control consequent subduction and sea level highstand, especially during deposition of the Sewa Formation. Geochemical proxies that relate to shelf carbonate production are calcium, strontium, whereas proxies that relate to siliciclastics include titanium, zirconium, manganese, aluminium, and silicon, other redox-sensitive proxy like uranium is also implemented. This indicates that chemostratigraphic proxies are a promising tool for the interpretation of sea level cyclicity in terms of systems tracts and bounding surfaces.
关键词	Sea level cycles Transgressive-regressive sequences chemostratigraphy palynological analysis toarcian oil shales bilong co section
英文关键词	SEDIMENTARY ORGANIC-MATTER; HEMIPELAGIC CARBONATES; DYNAMIC TOPOGRAPHY; NORTHERN TIBET; BLACK SHALES; AREA; ENVIRONMENT; CONTINENTS; COLLISIONS; EVOLUTION
WOS研究方向	Geology
WOS记录号	WOS:000914371600001
来源期刊	INTERNATIONAL GEOLOGY REVIEW
文献类型	期刊论文
条目标识符	http://gcip.llas.ac.cn/handle/2XKMVOVA/283296
作者单位	Southwest Petroleum University; Southwest Petroleum University; Egyptian Knowledge Bank (EKB); Minia University; Chengdu University of Technology; Chengdu University of Technology
推荐引用方式 GB/T 7714	Mansour, Ahmed,Xia, Guoqing,Fu, Xiugen,et al. Sea level changes and sequence stratigraphy of the Lower-Middle Jurassic Quse and Sewa formations in the Qiangtang Basin, central Tibet: Geochemical and palynological perspectives[J],2023,65(18).
APA	Mansour, Ahmed,Xia, Guoqing,Fu, Xiugen,&Wang, Jian.(2023).Sea level changes and sequence stratigraphy of the Lower-Middle Jurassic Quse and Sewa formations in the Qiangtang Basin, central Tibet: Geochemical and palynological perspectives.INTERNATIONAL GEOLOGY REVIEW,65(18).
MLA	Mansour, Ahmed,et al."Sea level changes and sequence stratigraphy of the Lower-Middle Jurassic Quse and Sewa formations in the Qiangtang Basin, central Tibet: Geochemical and palynological perspectives".INTERNATIONAL GEOLOGY REVIEW 65.18(2023).