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Magnetic susceptibility (MS) data were obtained from 11 sections of the Doushantuo (Edicaran) cap carbonate that directly overlies the Nantuo glacial diamictite in the southeastern margin of the Yangtze plat- form. The MS data revealed two regionally correlatable peaks at the bottom and top of the cap carbonate, sepa- rated 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 con- trolled mainly by detrital components during the first phase of cap carbonate deposition at the end of the glacia- tion. 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 geo- physical record for the rapid climate change from icehouse to greenhouse conditions in the aftermath of the Neoproterozoic “snowball Earth” event.
Magnetic susceptibility (MS) data were obtained from 11 sections of the Doushantuo (Edicaran) cap carbonate that directly overlies the Nantuo glacial diamictite in the southeastern margin of the Yangtze plat- form. The MS data revealed two regionally correlatable peaks at the bottom and top of the cap carbonate, sepa- rated 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 con- trolled mainly by detrital components during the first phase of cap carbonate deposition at the end of the glacia- tion. The upper MS peak is associated with high clay content and iron sulfides, and can be coated either 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 abunda The regionally consistent MS curves from the cap carbonates provided the first geo- physical record for the rapid climate change from icehouse to greenhouse conditions in the aftermath of the Neoproterozoic “snowball Earth” event.