Skip to Main Content
Book Chapter

A new sequence stratigraphic model for the Silurian A-1 Carbonate (Ruff Formation) of the Michigan Basin

By
Matthew J. Rine
Matthew J. Rine
Department of Geosciences, Western Michigan University, 1903 W. Michigan Avenue, Kalamazoo, Michigan 49008-5241, USA
Search for other works by this author on:
Stephen E. Kaczmarek
Stephen E. Kaczmarek
Department of Geosciences, Western Michigan University, 1903 W. Michigan Avenue, Kalamazoo, Michigan 49008-5241, USA
Search for other works by this author on:
Jonathan D. Garrett
Jonathan D. Garrett
Department of Geosciences, Western Michigan University, 1903 W. Michigan Avenue, Kalamazoo, Michigan 49008-5241, USA
Search for other works by this author on:
Published:
May 10, 2018
Publication history
09 June 2017

ABSTRACT

The A-1 Carbonate is the primary hydrocarbon source rock and an important reservoir component of the Silurian (Niagaran) pinnacle reef complexes in the Michigan Basin. The geology of the A-1 Carbonate, however, is not widely known because the majority of published research about this hydrocarbon system focuses on the pinnacle reefs. To gain a better understanding of the sedimentology and stratigraphy of the A-1 Carbonate, we integrated data from slabbed core, thin section petrography, gamma-ray logs, and energy-dispersive X-ray fluorescence spectrometry (ED-XRF). Thirteen distinct lithofacies within the A-1 Carbonate are recognized, with inferred depositional environments ranging from intertidal-sabkha to deep basin. The recognition of deep-water lithofacies contrasts significantly with previous interpretations of the A-1 Carbonate as a shallow, peritidal deposit.

Lithofacies stacking patterns and ED-XRF elemental trends within the A-1 Carbonate are consistent with basinwide sea-level fluctuations that resulted in deposition of three major stratigraphic units, called the Lower A-1 Carbonate, Rabbit Ear Anhydrite, and Upper A-1 Carbonate. The basal part of the Lower A-1 Carbonate was deposited during a basinwide transgression, as evidenced by deep-water pelagic carbonate accumulation in the basin center, lithofacies that become progressively muddier from bottom to top, and higher concentrations of Si, Al, and K upward, which are interpreted to reflect the influx of continental sediments. The subsequent highstand deposits of the upper part of the Lower A-1 Carbonate are characterized by a decrease in Si, Al, and K, coupled with a shallowing-upward facies succession consistent with increased carbonate production rates. The Rabbit Ear Anhydrite, which bifurcates the Upper and Lower A-1 Carbonate units, exhibits a variety of anhydrite fabrics across a wide range of paleotopographic settings within the basin. The Rabbit Ear Anhydrite is interpreted to reflect a time-correlative sea-level drawdown, which caused basin restriction, gypsum deposition, and elevated concentrations of redox-sensitive elements, such as Mo and Ni. The Upper A-1 Carbonate represents sedimentation during another major basinwide transgression that culminated in the deposition of shallow-water microbialites on the crests of previously exposed Niagara reef complexes. Similar to the Lower A-1 Carbonate, the base of the Upper A-1 Carbonate exhibits elemental signatures indicative of continental influence, whereas the overlying highstand deposits are characterized by more normal marine conditions and lower concentrations of Si, Al, and K.

You do not currently have access to this article.
Don't already have an account? Register

Figures & Tables

Contents

GSA Special Papers

Paleozoic Stratigraphy and Resources of the Michigan Basin

G. Michael Grammer
G. Michael Grammer
Search for other works by this author on:
William B. Harrison, III
William B. Harrison, III
Search for other works by this author on:
David A. Barnes
David A. Barnes
Search for other works by this author on:
Geological Society of America
Volume
531
ISBN electronic:
9780813795317
Publication date:
May 10, 2018

GeoRef

References

Related

A comprehensive resource of eBooks for researchers in the Earth Sciences

Close Modal
This Feature Is Available To Subscribers Only

Sign In or Create an Account

Close Modal
Close Modal