Geochemistry of the deep-water silica-fillings in Marinoan cap dolostone in the South China
Description
the data of oxygen and silicon isotopes, and the trace element concentrations of the filled silica in the enigmatic structures of Ediacaran cap dolostone in South China.
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Oxygen isotope compositions for silica-fillings: an aliquot of 1.1 to 1.8 mg of residue powder was subjected to laser fluorination analysis employing a 25W MIR-10 CO2 laser. Silicon isotope compositions for silica-fillings: Silica (SiO2) was reacted with bromine pentaflouoride (BrF5) in a metal vacuum line to generate silicon tetrafluoride (SiF4). The resultant SiF4 gas was purified and cryogenically collected using liquid nitrogen. Silicon isotope ratios were measured on a MAT-253 mass-spectrometer. Trace element concentrations for silica-fillings:Samples were mixed with a lithium metatorate/tetroborate flux (molar ratio optimized per ME-MS81 specifications) and fused in a furnace up to 1025 ºC. The resultant fused bead was cooled to ambient temperature and subsequently dissolved in an mixed acid solution consisting of nitic (HNO3), hydrochloric acid (HCl), and perchloric acid (HClO4). Trace element measurements were performed using an inductively coupled plasma-mass spectrometry (ICP-MS, Perkin Elmer Elan 9000), equipped with a collision/reaction cell to mitigrate polyatomic interferences.
Institutions
- Ocean University of ChinaShandong, Qingdao