NEOPROTEROZOIC STROMATOLITES OF THE DEATH VALLEY REGION: LET THE REHABILITATION BEGIN

Stromatolites and their utility in biostratigraphy remain relatively unexplored and disregarded in the United States. This stems from a variety of reasons, among them semantic problems, no general “theory” on stromatolites, and limited appropriate modern analogs. In an effort to rehabilitate stromatolites as a biostratigraphic tool, we discuss examples from the Neoproterozoic of the Death Valley region, California, which indicate the untapped potential of stromatolites.

Two columnar branching stromatolites, one from the Beck Spring Dolomite (Alexander Hills) and the other from the Kingston Peak Formation (Kingston Range), are morphologically similar to two taxa described from Australia: Tungussia wilkatanna Preiss 1974 and Baicalia burra Preiss 1972. The Kingston Peak Formation stromatolite has short stumpy branches, branching is usually gently divergent, occasional bridges or extended peaks occur from and between columns, and laminae are of variable thickness, irregular, lensoidal, and discontinuous across columns (numerous micro-cross-laminations). This stromatolite resembles B. burra from the Burra Group of Australia. The Beck Spring Dolomite stromatolite is characterized by an erratic growth habit, branches are elongate, it has a markedly divergent branching, some branches grow horizontally, there are no bridges, the margins are ragged, and laminae are generally smooth, regular, and of uniform thickness. This stromatolite resembles T. wilkatanna, also from the Burra Group. The two Australian taxa are widespread (South Australia, Northern Territory, Western Australia) and restricted to strata older than Sturtian glaciation (>~659 Ma) and younger than ~777 Ma (Boucaut volcanics). The Kingston Peak Formation stromatolite-bearing unit occurs below diamictite but above a basal conglomerate that appears to overlie the Beck Spring Dolomite. The exact position of the unit is complicated by slide blocks (is it one?) that occur in the Kingston Range.

The permissible evidence indicates that B. burra and T. wilkatanna occur in California and are time-synchronous with the same taxa in Australia. For at least this example, stromatolites apparently can be used for international correlations. In the absence of any other accepted correlation tool, resurgence of stromatolite studies seems warranted.