Identification of the thick-layer greigite in sediments of the South Yellow Sea and its geological s

• 作 者: Jianxing Liu Xuefa Shi Shulan Ge Qingsong Liu Zhengquan Yao Gang Yang
• 机 构: Paleomagnetism and Geochronology Laboratory (SKL-LE),Institute of Geology and Geophysics, Chinese Ac
• 出 处: Chinese Science Bulletin
• 发表日期: 2014年22期
• 关键词: thick tectonic shelf anoxic continental prerequisite exact rock coercivity miner

Magnetic minerals in sediments of the continental shelf are sensitive to environmental changes.Therefore,to determine the exact phases of magnetic minerals is the prerequisite to investigate the paleoenvironmental significances.In this study,a comprehensive rock magnetic investigation,coupled with mineralogical studies,was carried out on the long core NHH01(with a length of 125.64 m)from the central continental shelf of the South Yellow Sea.Single-domain greigite was identified as the dominant magnetic carrier in sediments between44.90 and 51.80 m,and terrigenous magnetite is the major magnetic phase in the adjacent layers.The existence of greigite unambiguously indicates an anoxic environment.We tentatively interpreted that such an environment could be formed by the fast sea level changes,long-existing of the cold eddies during warm stages,or in a lake which might be related to locally tectonic uplifting.Therefore,the occurrence of the thick-layer greigite could supply a new perspective to paleoenvironmental or even tectonic studies.

Magnetic minerals in sediments of the continental shelf are sensitive to environmental changes.Therefore, to determine the exact phases of magnetic minerals is the prerequisite to investigate the paleoenvironmental significances.In this study, a comprehensive rock magnetic investigation, coupled with mineralogical studies, was carried out of the long core NHH01 (with a length of 125.64 m) from the central continental shelf of the South Yellow Sea. Single-domain greigite was identified as the dominant magnetic carrier in sediments between 44.90 and 51.80 m, and terrigenous magnetite is the major magnetic phase in the adjacent layers. The existence of greigite unambiguously indicates an anoxic environment. We tentatively interpreted that such an environment could be formed by the fast sea level changes, long-existing of the cold eddies during warm stages, or in a lake which might be related to locally tectonic uplifting.Therefore, the occurrence of the thick-layer greigite could supply a new perspecti ve to paleoenvironmental or even tectonic studies.