Entry number：24
SUBJECT
Snowball Earth Climate Change Event- Carbonate, Phosphate Chemical Composition
DEPARTMENT
Department of Earth Sciences
PROFESSOR AND STUDENT
Professor：
Student：Lee, Cheng-Hong
ABSTRACT
Snowball Earth is a very important extreme climate change event that happened in Earth early history had deeply influenced the multicellular organism evolution. The samples were collected from Doushantuo formation (south China) where had massive Precambrian fossils is focus research area for Snowball Earth research. The Petrography had observed the fossils existence though polarizing microscope. Then, we can confirm the major mineral in the sample is Dolomite with some Apatite and a few of Pyrite with SEM-EDS and Element mapping. The fossils in Doushantuo layer was belonging to the Ediacaran biota (Muscente et al, 2015). The major minerals’ characteristic peak had been observed and detected some important carbon materials’ signal through raman spectrum (D-bands (1350 cm-1) and G-band (1580 cm-1)), providing more evidence that there had biota existed. We use multi-step sequence extraction to extract carbonate phase and phosphate phase respectively for element analyze. Then using ICP-QMS to measure Ca (15-35 mg/g), Mg (0.7-13.5 mg/g), P (3-5 mg/g) had uncovered the samples’ chemical composition change with different depth. The rock samples’ chemical composition change can record the sedimentary environment and sediment sources indicating there was still have extreme environment change after the Snowball Earth event and recording multiple diagenesis of carbonate and phosphate. At the end, we compare the fossils morphology to understand Precambrian biota evolution was undergoing a rapid accumulation of sediments and environment change extremely condition.
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