Date of Award:

5-2000

Document Type:

Thesis

Degree Name:

Master of Science (MS)

Department:

Geosciences

Department name when degree awarded

Geology

Committee Chair(s)

W. David Liddell

Committee

W. David Liddell

Committee

Peter Kolesar

Committee

Jim Evans

Abstract

The majority of the Middle Cambrian Wheeler Formation in the Drum Mountains was deposited during a single 3rd order sequence. Superimposed onto this sequence are three indistinct 4th order cycles and twenty distinct 5th order cycles. These higher order cycles were likely deposited within short intervals of geologic time (204 to 405 ky).

The lower sequence boundary zone occurs within the Swasey Formation. The Transgressive Surface is the contact between the Swasey and Wheeler Formations. The Maximum Flooding Surface is located near the top of the lower Wheeler Formation, which also approximates the base of the Ptychagnostus atavus range zone. The upper sequence boundary is marked by stromatolites, which occur near the top of the upper member of the Wheeler Formation in the Drum Mountains.

Deposition of the Wheeler Formation in the Drum Mountains was controlled by eustacy and tectonics. Local normal faulting associated with Middle Cambrian post-rifting thermal subsidence may have caused some of the 5th order cycles.

The cycles and surfaces defined in this stratigraphic analysis, and the base of the Ptychagnostus atavus and P. gibbus range-zones, can be used to correlate strata occurring in other localities in the eastern Great Basin. In addition, this study enables the evaluation of the effect of tectonics (faulting) versus global eustacy on the sedimentary regime occurring within the Middle Cambrian House Range Embayment.

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