--> ABSTRACT: Mesozoic Folds, Fossil Fields, and Future Finds (?), by Gary W. Newman and George G. Witter; #91030 (2010)

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Mesozoic Folds, Fossil Fields, and Future Finds (?)

Gary W. Newman, George G. Witter

Drilling and surface geologic mapping have shown that pre-Tertiary, post-Triassic folds and upthrusted anticlines in an eastern Nevada foldbelt have accumulated major oil columns. This Mesozoic foldbelt involves a Cambrian through Triassic section, which has hundreds of feet of porosity in Ordovician sandstones, Silurian and Devonian carbonates, and Mississippian sandstones. In addition to the Devonian Pilot and Mississippian Chainman Shales, source rocks are found in Cambrian and Ordovician shales and in some Paleozoic carbonates.

The occurrence of live and dead oil shows in hundreds of vertical feet of porosity in wells drilled on several of these Mesozoic structures is interpreted as evidence that these structures were giant oil fields prior to being breached by Tertiary Basin and Range extensional faulting, which allowed vertical hydrocarbon leakage. Noting that undrilled Mesozoic structures still exist in the foldbelt and noting that natural processes are seldom 100% efficient--including, probably, the disruptive effects of Basin and Range extensional faulting--the authors suggest that there is a very good chance of finding one or more giant fields in the remaining structures of this foldbelt.

AAPG Search and Discovery Article #91030©1988 AAPG Annual Convention, Houston, Texas, 20-23 March 1988.