CHEMOSTRATIGRAPHY OF NEOPROTEROZOIC-CAMBRIAN UNITS, WHITE-INYO REGION, EASTERN CALIFORNIA AND WESTERN NEVADA - IMPLICATIONS FOR GLOBAL CORRELATION AND FAUNAL DISTRIBUTION

Comparison of secular variations in carbon-isotopic compositions of carbonates from the Neoproterozoic-Cambrian succession in the White-Inyo region of eastern California with similarly-aged sequences worldwide suggests that, in California, a hiatus potentially encompassing the latest Neoproterozoic and much of the Tommotian may be present. The hiatus is found between the carbonate units in the Lower Deep Spring Formation, suggesting that the lower-most Deep Spring, Reed, and Wyman formations are Neoproterozoic in age, and the remaining Deep Spring Formation is uppermost Tommotian or Atdabanian in age. It is unclear where the Neoproterozoic-Cambrian boundary may lie, since chemostratigraphic data is not available for the boundary in Newfoundland type section, but it is most-likely encompassed within the inferred hiatus. Studies calculating ''similarity coefficents'' of the North American fossils to determine the relative separation of Neoproterozoic-Cambrian continents, the global distribution of faunas, and timing of the breakup of a Neoproterozoic supercontinent may be questioned, in light of this potential hiatus. Integration of the chemostratigraphic record with trace fossil asemblages in California corroborates an earlier suggestion that basal Tommotian faunas in Siberia are apparently older than the first appearance of diverse small shelly fossils in China.