The Ediacaran is the most dramatic period when the oldest animals appeared, and decoding surface environmental change is one of the key issues. We carried out drilling in Three Gorges area, south China to collect complete section from the Marinoan Snowball Earth to early Cambrian. We made chemostratigraphies of δ13C, 87Sr/86Sr, δ18O, δ88/86Sr and δ44/42Ca, and Fe, Mn, REE and P contents of carbonates and δ13C of organic carbon mainly of the drill cores to estimate primary productivity (PP), oxidation of DOC, continental weathering influx (CW), temperature, nutrient contents, and redox condition of seawater (SW). Its comparison with fragmented records of other sections in the world indicates it shows primary and global change of SW chemistry.
In the Ediacaran, are at least six negative and positive δ13C excursions: N1-N6 and P1-P6, respectively. Especially, the large negative values correspond to cap carbonate (N1), 580 Ma Gaskiers glaciation (N4), and the Shuram excursion (N6), respectively. Large δ88/86Sr and δ44/42Ca anomalies, and high 87Sr/86Sr values and high P contents around N1 indicate high Ca, Sr and P contents of SW supplied by CW. At N4, line of evidence of regression, positive δ18O and negative δ13C excursions indicates global cooling and consequent decomposition of buried OC. δ18O and δ13C excursions precede positive 87Sr/86Sr excursion, indicating global cooling raised CW. The termination of the global cooling, defined by the maximum δ18O value, is coincident with the beginning of δ13C, 87Sr/86Sr, Fe and Mn content changes, namely recovery of PP, transgression, and oxidation of SW, respectively. At the early stage of N6, increase of 87Sr/86Sr precedes and Fe and Mn contents and the large negative Shuram δ13C excursion, indicating that high CW possibly due to building of Transgondwanan Supermountains caused enhancement of sulfate reduction and remineralization of DOC due to high sulfate influx and deoxidation of SW, inconsistent with the idea that oxidation of surface environment caused the Shuram excursion. At the late stage, decrease in Fe and Mn contents and large Ce anomaly suggest oxidation of shallow seawater.
Our data indicate simultaneity of emergence of Metazoan and Ediacara Fauna and the 87Sr/86Sr positive anomaly, and suggest that enrichment of nutrients in seawater due to enhanced CW possibly caused sudden biological evolution instead of increase of oxygen content of seawater.

In Ariel's laboratory, we analyze Mo isotopes of the Ediacaran and Early Cambrian samples in South China, and try to estimate redox condition of seawater and sufficiency of Mo in seawater for multicellular algae.