Date of Award

4-2019

Degree Name

Doctor of Philosophy

Department

Geological and Environmental Sciences

First Advisor

Dr. Stephan Kaczmarek

Second Advisor

Dr. Patrick McLaughlin

Third Advisor

Dr. William Harrison III

Fourth Advisor

Dr. Andrew Caruthers

Keywords

Michigan Basin, sequence stratigraphy, Pinnacle reefs, Silurian, carbon isotopes, carbonates

Abstract

Constraining the ages of sedimentary strata is challenging and is the principle source of stratigraphic uncertainty in sedimentary basins worldwide. The story is no different in the Michigan Basin, where our current understanding of the Silurian Niagara-Lower Salina stratigraphic record is based in large part on limited sedimentological and chronological data, resulting in a collection of models that disagree about the timing of deposition. This disagreement marks the starting point for the dissertation research presented here. The studies included in the dissertation integrate conventional and novel approaches to address the stratigraphic uncertainty that has plagued Silurian reef researchers for decades. Chapter I reviews the current state of knowledge and outlines the key geological questions surrounding the salt-encased Silurian reefs of the Michigan Basin. Chapter II documents how core and wireline log data are utilized from four reef complexes within the basin to establish a new depositional model for the reefs that more accurately reflects our modern understanding of how environmental controls affect reef development and architecture. In Chapter III, high-resolution elemental data derived from energy dispersive x-ray fluorescence elemental data are integrated with sedimentological observations to further constrain basin-wide sequence stratigraphic interpretations of the Silurian reefs. Chapter IV addresses the problem of age constraint by using carbon isotope chemostratigraphy in conjunction with facies observations, conodont biostratigraphy, and U-Pb age-dating. Together, these datasets are used to constrain the timing of deposition of the Silurian reefs and surrounding salts, thus allowing robust, basin-wide sequence stratigraphic and relative sea level models to be developed. The novel approach described in Chapter IV of this dissertation allows for intra-basinal and global correlations to be achieved, with temporal resolution better than is generally possible. As a result, this study demonstrates the importance of integrating a suite of conventional and analytical tools to constrain sequence stratigraphic relationships across individual sedimentary basins which may include a wide variety of depositional environments.

Access Setting

Dissertation-Open Access

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