When was salt and gypsum deposited in nys




















This paper details the stratigraphy and facies changes of the mined gypsum bed and enclosing strata of the Upper Silurian Salina Group A unit at the Westroc Industries Ltd. At both localities, the Salina A unit comprises three sedimentary cycles, each terminating with gypsum.

The sequence at Westroc indicates that the Algonquin arch became an emergent feature during late SalinaA-2 time. The mined gypsum bed Main Gypsum bed at Westroc forms the top of cycle 1 and marks the first appearance of gypsum beds in the Salina Group, above the contact with the underlying Upper Silurian Guelph Formation. Stratigraphically, the Main Gypsum bed correlates with the base of the Salina A-2unit. At Westroc, the two overlying gypsum beds in the Salina A-2 are uneconomic.

Incontrast, the economic gypsum bed at Domtar marks the base of the overlying Salina B anhydrite top of cycle 4 and is underlain by three uneconomic gypsum beds stratigraphic equivalents of the three Salina A-2 gypsum beds at Westroc. However, the model also predicts the possibility of continental salina or playa deposits along the axis, or northwest, of the Algonquin arch during early Salina Group time.

This is a preview of subscription content, access via your institution. Rent this article via DeepDyve. Google Scholar. COLE, G. DEAN, W. Article Google Scholar. Write your answer Related questions. What is the geologic age of the salt and gypsum deposits found in new york state bedrock?

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Some of these reefs can be seen today on the south side of Chicago, and I crosses over a giant quarry into one of them.

Assuming that the Silurian reefs formed in an environment similar to modern reefs, we can infer something about the Great Lakes area during this time. All modern reefs grow on a shallow bottom, no deeper than the depth of light penetration generally about 60 m.

Furthermore, coral reefs are restricted to tropical regions where water temperatures are consistently above 77 o F. Thus, the presence of extensive reefs around the Michigan Basin during the Silurian suggests a shallow tropical or sub-tropical environment.

Well-preserved fossils in most of these ancient reefs substantiate this assumption. Outward from the reefs, in the deeper water, muds rich in CaCO 3 accumulated on the floor of the vast shallow seas, generally producing thinly bedded dolomite that contains few fossils. But the genial climates of the Silurian came to an end. The close of the Silurian was a long time of aridity in which the seas became so salty that living creatures swam to a more suitable home.

The conditions were roughly analogous to the present-day Mediterranean Sea where water from the Atlantic flows in over the rather shallow restriction at the Straits of Gibraltar.

The arid climate in the region evaporates the sea water and concentrates the salt. The heavier, highly saline water sinks to the bottom and cannot escape and therefore tends to accumulate.

Great salt beds named the Salina Salt Beds were deposited in the basin. In the central part of the basin feet of alternating salt, shale, and limestone beds have been penetrated in the Salina, with feet of rock salt.

The rock salt bowl becomes thinner towards its rim. Source: Detroit Free Press Thus, visualize a subsiding, circular basin in lower Michigan, surrounded by shallow waters and coral reefs. At that time the Great Lakes area was near the equator, and as a result, there was extensive evaporation of sea water.

To make up for this, salt water was constantly being added to the Michigan evaporation Basin through shallow passages in the reefs. Waters in the basin were therefore saltier than in the "open ocean" outside of the basin.



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