Identifying Tectonic Influences in Devonian Carbonate Strata: A Quantitative Stratigraphic Analysis of the Guilmette Formation, Eastern Nevada
Bowie, Christopher M. and Brady, Mara E.
The Middle to Upper Devonian Guilmette Formation was quantitatively analyzed to interpret patterns in cycle thickness and composition related to the transition from a long lived passive continental margin to an active convergent setting. The goal of this study was to identify significant tectonic events by anomalous deviations from mean cycle thickness, facies composition, and sedimentation rate within the Formation. In the database created from previously published literature, we recognize over 170 parasequences in the eleven previously identified 3rd to 4th order sequences. Each sequence was considered individually to observe trends in the number of parasequences per sequence, and mean parasequence thickness. Strong deviations from the mean (> 2σ) were interpreted as abnormally thick accumulations in response to increased tectonic subsidence. Of the previously recognized sequences, two consecutive sequences contain anomalously thick deep water accumulations, an increase in sedimentation rate, and “give-up” style parasequences, all of which are indicative of tectonic subsidence outpacing sediment accumulation. The timing of the proposed increase in subsidence in this study is consistent with previously published estimates from elsewhere in the Great Basin and likely represents the growth of the initial back-bulge basin during the collision of the Antler island-arc with the North American continent during the early hassi conodont biozone.
AAPG Search and Discovery Article #90162©2013 Pacific Section AAPG, SPE and SEPM Joint Technical Conference, Monterey, California, April 19-25, 2013