Magnetic susceptibility variations of the Ediacaran cap carbonates in the Yangtze platform and their implications for paleoclimate

• Published in: Chinese journal of oceanology and limnology Vol. 23; no. 3; pp. 291 - 298
• Main Author: 吴怀春 张世红 蒋干清 李海燕
• Format: Journal Article
• Language: English
• Published: Dordrecht Springer Nature B.V 01.09.2005; State key Laboratory of Geological Processes and Mineral Resources; Key Laboratory of Lithosphere Tectonics and Lithoprobing Technology of Ministry of Education, China University of Geosciences, Beijing 100083, China%Department of Geoscience, University of Nevada, Las Vegas, NV89154-4010,USA
• Subjects: Anoxia; Carbonates; Climate change; Components; Deposition; Glaciation; Glaciology; Greenhouses; Iron; Iron sulfides; Magnetic permeability; Magnetic susceptibility; Magnetism; Marine geology; MS技术; Palaeoclimatology; Paleoclimate; Paleoclimate science; Platforms (geology); Studies; Sulfides; 古气候; 地质气候; 磁化率; China, People's Rep., Yangtze Platform; cap carbonates; magnetic susceptibility (MS); Yangtze platform; Doushantuo Formation; paleoclimate
• ISSN: 0254-4059; 2096-5508; 1993-5005; 2523-3521
• DOI: 10.1007/BF02847151

Magnetic susceptibility (MS) data were obtained from 11 sections of the Doushantuo (Ediacaran) cap carbonate that directly overlies the Nantuo glacial diamictite in the southeastern margin of the Yangtze platform. The MS data revealed two regionally correlatable peaks at the bottom and top of the cap carbonate, separated by an interval of low values. The lower MS peak coincides with high percentage of insoluble siliciclastic residues that are compositionally identical to the matrix of the underlying diamictite, suggesting its origin controlled mainly by detrital components during the first phase of cap carbonate deposition at the end of the glaciation. The upper MS peak is associated with high clay content and iron sulfides, and can be interpreted as either derived from enhanced greenhouse weathering that could have brought more terrigenous components into the ocean, or the result of ocean anoxia at the late stage of cap carbonate deposition that could led to formation of abundant iron sulfides. The regionally consistent MS curves from the cap carbonates provided the first geophysical record for the rapid climate change from icehouse to greenhouse conditions in the aftermath of the Neoproterozoic “snowball Earth” event.