Date of Graduation

Fall 2011

Degree

Master of Science in Geospatial Sciences

Department

Geography, Geology, and Planning

Committee Chair

Kevin Evans

Abstract

The detailed sequence stratigraphy of lower and middle Mississippian rocks in southwestern Missouri is poorly known; previous stratigraphic studies primarily have focused on biostratigraphy, lithostratigraphy, and depositional environments. Field studies of new road cuts along highways 13, 65, 71, and private roads provide additional exposures that allow for an interpretive sequence-stratigraphy model that can be correlated from mid-ramp to platform and inner-shelf settings in a southwest-northeast transect. A sequence boundary at the base of the Bachelor Formation rests with angular unconformity on upper Devonian Shale in southwesternmost Missouri and, elsewhere, cuts out lower Ordovician carbonates. An upper sequence boundary is recognized, where the upper Mississippian Hindsville Formation uncomformably overlies the middle Mississippian Keokuk Limestone. Between these sequence boundaries are other sequence boundaries. The Compton Limestone records relative sea-level deepening. It is truncated locally with low-angle discordance below the Northview Formation, a mixed shale and siltstone succession. The Northview accumulated in a near-shore setting and prograded across the platform and middle ramp. The overlying Pierson Formation records relative deepening, and the top of the unit is truncated at the base of the Reeds Spring Formation, where interbedded lime mudstone and chert record marked deepening. In contrast, the overlying Elsey and Burlington-Keokuk formations record shoaling. The mechanism for sea-level change remains uncertain, but tectonism provides a possible explanation for truncation of stratigraphic units at the base and top of this interval.

Keywords

Missouri, sequence, stratigraphy, hardground, sea-level change

Subject Categories

Geology | Stratigraphy

Copyright

© Jeremiah S. Jackson

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