ABSTRACT: Changes of Salina A and B Lithofacies from the Michigan to Appalachian Basins: Salt Solution or Non-deposition in the Salina Group?
Simon J. Haynes, Brock University, St. Catharines, ON, Canada
This paper examines the 3-dimensional lithofacies of the Salina A and B units present in underground salt mines in the Michigan (Goderich mine, Ontario) and Appalachian (Retsof mine, Upper New York State) basins, and the gypsum mines in the intervening area of the Algonquin Arch (Domtar and Westroc mines, Ontario).
Across the Algonquin Arch, key lithofacies such as algal mats, stromatolitic mounds and selenite-disc fabrics indicate that Salina A and B evaporites were deposited as gypsum in coastal salinas, lagoons and sabkhas in a semi-arid coastal environment similar to modern deposition in northern Egypt and South Australia. In contrast, the Salina A-2 salt at the Goderich mine is circa 15 m of massive halite with thin black bands of clay and opaque material. Such a gypsum-deficient environment is not easy to reconcile with tectonic drawdown or barred-basin models of evaporite deposition in the Michigan basin but is consistent with semi-arid marine and/or terrestrial salinas. The Salina B at the Retsof mine is also gypsum/anhydrite-deficient and comprises 5 halite beds (each circa 3-4 m thick) interbedded with halitic dolomite, dolomitic mudstones and halitic shales. This is similar to the modern halitic lagoons at the mouth of the Nile delta.
The implication of these proposed depositional models is that halite could have precipitated, without gypsum/anhydrite, about Guelph-Salina reef plays during epeirogenic uplift; and dissolved later during either epeirogenic submergence and/or tectonism (Acadian and Alleghenian orogenies).
Search and Discovery Article #90907©2000 AAPG Eastern Section Meeting, London, Ontario, Canada