Massive formation of early diagenetic dolomite in the Ediacaran ocean: Constraints on the "dolomite problem"

International audiencePaleozoic and Precambrian sedimentary successions frequently contain massive dolomicrite [CaMg(CO3)(2)] units despite kinetic inhibitions to nucleation and precipitation of dolomite at Earth surface temperatures (100 degrees C, thus raising doubt about the validity of these deposits as archives of Earth surface environments. We present a high-resolution, >63-My-long clumped-isotope temperature (T-Delta 47) record of shallow-marine dolomicrites from two drillcores of the Ediacaran (635 to 541 Ma) Doushantuo Formation in South China. Our T-Delta 47 record indicates that a majority (87%) of these dolostones formed at temperatures of <100 degrees C. When considering the regional thermal history, modeling of the influence of solid-state reordering on our T-Delta 47 record further suggests that most of the studied dolostones formed at temperatures of