The Ordovician strata of the Lower Member of the Vinini Formation comprise a sequence of greenstone, sandstone, shale, and siltstone representing the prograding and retrograding of submarine fans along the continental margin. Although graptolites are normally preserved within shale beds in the Lower Member of the Vinini Formation, the greatest abundance of well preserved graptolites is found within the sandstone turbidite beds. These graptolites are uniquely preserved in full relief as opposed to being flattened on shale. It is interpreted based on fragmentation and species composition within the sandstone that the graptolites flourished in an upwelling zone on the continental margin and that as their remains accumulated on the underlying seafloor, were swept downslope in turbidity currents.
Graptolites were collected from 10 beds within the stratigraphic section and represent 33 taxa from 17 genera. There are no new taxa. All taxa are described, illustrated, and compared to other collections.
|Commitee:||Behl, Richard, Francis, Robert|
|School:||California State University, Long Beach|
|School Location:||United States -- California|
|Source:||MAI 54/04M(E), Masters Abstracts International|
|Subjects:||Morphology, Geology, Paleontology|
|Keywords:||Graptolites, Morphometrics, Nevada, Ordovician, Vinini formation, Whiterockian|
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