Tectonostratigraphic evolution of the <em>c.</em> 780–730 Ma Beck Spring Dolomite: Basin Formation in the core of Rodinia Emily F. Smith Francis A. MacDonald James L. Crowley Eben B. Hodgin Daniel P. Schrag 10.6084/m9.figshare.3453938.v1 https://geolsoc.figshare.com/articles/dataset/Tectonostratigraphic_evolution_of_the_em_c_em_780_730_Ma_Beck_Spring_Dolomite_Basin_Formation_in_the_core_of_Rodinia/3453938 <p>The Beck Spring Dolomite is a mixed carbonate–siliciclastic succession exposed in Death Valley, California, that was deposited between 780 and 717 Ma. Along with its bounding units, the Horse Thief Springs Formation below and unit KP1 of the Kingston Peak Formation above, the Beck Spring Dolomite were deposited in one of the ChUMP (Chuar–Uinta Mountains–Pahrump) basins with subsidence commonly attributed to the nascent rifting of Rodinia. These pre-Sturtian successions preserve eukaryotic microfossil assemblages, diverse microbialites, and large carbon isotope anomalies directly below Sturtian-age glacial deposits. Here we present new geological mapping, measured stratigraphic sections, carbon isotope chemostratigraphy and detrital zircon geochronology from the Beck Spring Dolomite and its bounding units. The carbon isotope excursion at the top of the Beck Spring Dolomite has previously been attributed to meteoric diagenesis associated with karst breccias, but here we demonstrate that these breccias are instead mass flow deposits that formed during deposition of the Kingston Peak Formation and that the carbon isotope excursion is not only reproducible throughout the basin, but is associated with transgression rather than regression and exposure. In addition, we refine local correlations and discuss the use of chemostratigraphic curves from these units for regional and global correlations. The Beck Spring Dolomite was deposited during the second of three distinct basin-forming events recorded in the Pahrump Group with basin inversion occurring between each event. The presence of syn-sedimentary faults, the character of the lateral facies change and detrital zircon provenance analyses indicate that the Beck Spring Dolomite fringed a coeval palaeo-high to the south in a tectonically active basin. Detrital zircon age distributions in the Beck Spring Dolomite show sharp probability peaks at <em>c.</em> 1200, 1400 and 1800 Ma, consistent with local sources to the SW in the Mojave block rather than transcontinental rivers. The <em>c.</em> 1800 Ma probability peak is less prominent in the KP1 samples. In addition, KP1 also records slump folding and is overlain by an unconformity. We suggest that these features are consistent with the emergence of a local fault to the NE. Deposition of the Beck Spring Dolomite and bounding units do not record evidence of incipient rifting of the western margin of Laurentia but instead reflect a distinct and separate tectonothermal event. </p> 2016-06-21 11:47:18 tectonothermal event Pahrump Group Basin Formation mass flow deposits Kingston Peak Formation probability peaks detrital zircon geochronology Horse Thief Springs Formation detrital zircon provenance analyses Beck Spring Dolomite eukaryotic microfossil assemblages carbon isotope excursion NE Tectonostratigraphic evolution 717 Ma stratigraphic sections SW Detrital zircon age distributions Mojave block carbon isotope anomalies record evidence carbon isotope chemostratigraphy 1800 Ma probability peak KP 1 chemostratigraphic curves KP 1 samples karst breccias Death Valley facies change basin inversion 1800 Ma records slump unit KP 1 Beck Spring Dolomite show Geology