3:30 PM - 4:45 PM
[BPT06-P03] Radiogenic Sr isotope excursions in the Ediacaran seawater
Keywords:South China, Radiogenic Sr isotope ratio
The weathering influx from continents is thought to be a major influence on the change in composition of ancient seawater and on biological evolution. Its flux can be estimated from the 87Sr/86Sr ratio of carbonate rocks. Due to the large isotopic difference between these two main sources of strontium, the 87Sr/86Sr composition of seawater tracks the long-term changes in the weathering of the continental surface relative to the hydrothermal flux. For further understandings of regional variation of the 87Sr/86Sr ratio in the Ediacaran, we carried out on-land drilling of the Ediacaran Doushantuo Formation at Three Gorges, Weng’an, Siduping, and Tianping areas. We prepared rock powders from the carbonate rocks, and dissolved them in 2 M acetic acid at 70 Celsius degrees for 24 hours. After removing coexisting matrix elements using a chromatographic technique, Sr isotope compositions were measured with a MC-ICP-MS. Along with the data from previous studies, we review the radiogenic Sr isotope excursions in the Ediacaran carbonate rocks and discuss the cause of regional variations.