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Provenance Study of Fe–Ti Oxide Minerals in the quaternary sediments in Yichang Area and Its Implication of Formation Time of the Yangtze Three Gorges, China

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Acta Geologica Sinica(English Edition) 2018年第4期92卷 1598-1608页

作者： XIANG Fang DU Wen HUANG Henxu KANG Dongya ZHU Hongbo FENG Qin State Key Laboratory of Oil and Gas reservoir Geology and exploitation Chengdu University of Technology Shangdong Provincial Key Laboratory of Depositional Mineralization & Sedimentary Mineral Shangdong University of Science and Technology Institute of sedimentary geology Chengdu University of Technology

The Three Gorges are considered to be critical to understand the formation of Yangtze River. Recent research results suggest that the Yangtze Three Gorges was created during the quaternary but the exact time is debatable. Fe-Ti oxide minerals are seldom used to study sediment provenance, expecially using scanning electron microscopy （SEM）, and energy dispersive spectrometer （EDS）. In this study, the provenance of quaternary sediments in Yichang area, which is located to the east of the Yangtze Three Gorges, was investigated by using SEM and EDS to research Fe-Ti oxides. The Panzhihua vanadium titanomagnetite and Emeishan basalt outcrop are located to the west of the Three Gorges. Further, the materials from them are observed in the quaternary sediments of Yichang area. Fe-Ti oxide minerals from the Huangling granite are observed in the Yunchi and Shanxiyao Formations, which were formed before 0.75 Ma B.P., whereas Fe-Ti oxide minerals from the Huangling granite, Panzhihua vanadium titanomagnetite, and Emeishan basalt are observed in the riverbed and fifth-terrace sediments of the Yangtze River, which were formed after 0.73 Ma B.P.. Thus, we can infer that the Three Gorges formed after the deposition of the Shanxi Formation and before the fifth-terrace; i.e., 0.75-0.73 Ma B.P..

关键词： Yangtze Three Gorges Yichang area quaternary sediments Fe-Ti oxide minerals China

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Coupling controls of neotec-tonism and paleoclimate on the quaternary sediments of the Yangtze (Changjiang) coast

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Science Bulletin 2005年第16期 105-114页

作者： WANG Zhangjiao1, CHEN Zhongyuan2, WEI Zixin3, WANG Zhanghua1 & WEI Taoyuan1 1. Department of Geography, East China Normal University, Shanghai 200062, China 2. State Key laboratory for Estuarine and Coastal Research, East China Normal University, Shanghai 200062, China 3. Shanghai Institute of Geological Survey, Shanghai 200072, China

Attempt has been made to discuss the coupling relation of neotectonism and paleoclimate that have played a critical role in controlling the quaternary sediment distribu-tion and sedimentary facies evolution on the Yangtze coast. On the basis of petrological analysis, up to six sedimentary cyclicities have been identified in the quaternary sediment boreholes on the time scale of 0.4―0.5 Ma. The lower sedi-mentary cyclicities (Pliocene to Early Pleistocene) are char-acterized largely by thicker gravelly coarse sands, topped by thinner fine silt and silty clay. Gravels are very angular and clayey gravels prevail. sediments are usually of poor sorting, rich in log fragments and have no microfossils. Bedload as denoted by C-M plot occurs throughout the section. This evidence represents the alluvial fan sedimentation which took place as the basin began to subside. The middle sedimentary cyclicities (often including Early to Middle Pleistocene) con-sist of basal gravelly sands and clayey silt at the middle and upper sediment sections. Sorting becomes relatively better, and foraminifer appears sporadically. C-M plot reveals the mixture of sediment transport media via bedload, saltation and suspension, representing sedimentation of braided river system at the early stage and subsequently, the sedimentation of meandering river pattern. The upper sedimentary cyclic-ities (including Late Pleistocene to Holocene) comprise basal gravelly sands (exclusive of the Holocene sediment) and thick fine sand and silty clay on the upper section. Sorting becomes fine and foraminifer appears throughout the sediment sec-tion. C-M plot shows that saltation and suspension serve as the main sediment transport media in the sediment section and bedload transport weakens. These evidence the sedi-mentation of meandering river pattern near coast during Late Pleistocene and Holocene time, when marine transgres-sion invaded into the paleoriver valleys, which often forms drowned-valley facies and shallo

关键词： quaternary sediments grain size neotectonic subsidence paleoclimate/sea-level fluctuations Yangtze delta.

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Soft Sediment Deformation Structures in the Sediment Deposits of Ganga River and Its Oxbow Lakes in Parts of Indo-Gangetic Plain: Implications for Quake Proxies and Paleoseismicity Tracking

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International Journal of Geosciences 2023年第1期14卷 75-93页

作者： Gufran Ali Mohd Sajid Mohammad Shamim Khan Department of Geology AMU Aligarh India

The Late quaternary thick sedimentary fills of the Ganga basin predominantly consist of unconsolidated fluvial sandy deposits which are often intercalated with mud. These deposits at various places record the evidence of earthquakes, which occurred in the recent geological past. The evidence is contained and manifested in the form of Soft Sediment Deformation Structures (SSDSs). Saturated sediments/muds/soils are liquefied by earthquake tremors which either generate SSDS or produce structural discordance in the pre-existing sedimentary structures. The present study reports the occurrence of SSDS, e.g. load and associated flame structures, clastic dikes and sill structures, slump structures and sedimentary breccias, etc. from the Ganga River and adjacent oxbow lake sediment deposits. An attempt has been made to establish the origin of soft sediment structures of this region in accordance with its neotectonic history and in turn, identification of seismic structural proxies to delineate paleoseismic events in this region with futuristic implications. The preservation of soft sediment deformation structures in large numbers with multiple geomorphology and scale, in the river and adjoining lake sediments, is indicative of frequent earthquakes of high magnitude consequent to tectonic activism in the Himalayan region.

关键词： quaternary sediments Flood Plain Central Ganga Basin Sediment Dynamism Himalayan Uplift Paleoquakes

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Optically Stimulated Luminescence Dating of sediments from the Pearl River Delta, Southeast China

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Journal of Earth Science and Engineering 2014年第6期4卷 378-384页

作者： Zhuolun Peng Guoneng Chen Rodney Grapes Yan Qiu Ke Zhang Jing Wang School of Earth Sciences and Geological Engineering Sun Yat-sen University Guangzhou 510275 China Key Laboratory of Marine Mineral Resources Ministry of Land and Resources Guangzhou 510075 China Guangzhou Marine Geological Survey Guangzhou 510075 China

The PRD （Pearl River Delta） was subjected to two transgressions respectively in the latest Pleistocene and Holocene. Position of coastal line of the latest Pleistocene transgression in some localities, especially at the center part of PRD is still uncertain. Thus quaternary sandy sediments in the central PRD are dated by OSL Optically Stimulated Luminescence） for determining the ancient coastal line. Samples are from Xiaohushan Hill at the center of PRD, where quaternary sediments deposited on a wave-cut platlbrm consist of two kinds of sediments： marine muddy-silt on the top and alluvial fine-sand in the lower part. The former is dated at 5.0-5.5 ka, which defines the time of Holocene transgression in the PRD. The alluvial fine-sand in the part is dated at 22-26 ka. For the alluvial fine-sand rests directly on a wave-cut platform, thus this wave-cut platform should have been existed before deposit of alluvial sand, i.e., formed during an earlier marine transgression that may have culminated in the sea level high at about 40 ka. The optically stimulated luminescence results are consistent with geological observations and compatible with TL （thermoluminescence） and ^14C ages from the same layers at other localities of the PRD.

关键词： quaternary sediments OSL dating transgression PRD.

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