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Bulge Migration and Pinnacle Reef Development, Devonian Appalachian Foreland Basin.
The Journal of Geology
|April 19, 2000
Summary
Detailed analysis of Devonian strata in the Appalachian Basin reveals a migrating forebulge and back-bulge basin, influencing sea level and topography. This suggests a "flexural welt" controlled reef development and guides future exploration for pinnacle reefs.
Area of Science:
- Geology
- Stratigraphy
- Paleogeography
Background:
- The Appalachian Basin experienced significant geological activity during the Devonian period.
- Understanding relative sea level changes and topographic inversions is crucial for interpreting basin evolution.
Purpose of the Study:
- To analyze Late Emsian and Early Eifelian carbonate strata in the northern Appalachian Basin.
- To investigate anomalous sea level changes and topographic inversions.
- To understand the development of the Appalachian foreland basin system.
Main Methods:
- Detailed stratigraphic analyses of carbonate-dominated strata.
- Mapping of unconformities, pinnacle reefs, and lithofacies/biofacies distribution.
- Interpretation of forebulge and back-bulge basin dynamics.
Main Results:
- Identified anomalous, locally varying relative sea level changes and topographic inversions.
- Documented the retrograde migration of a positive relief area (forebulge/flexural welt) and a migrating basin.
- Observed shallow-water reef development during sea level lowstand on the bulge crest.
Conclusions:
- The observed features suggest a "flexural welt" superposed on the Appalachian foreland basin system.
- The migrating bulge and transgression facilitated the growth of economically significant pinnacle reefs.
- Future reef exploration should focus on the projected bulge position during the basal Onondaga lowstand.