ABSTRACT: The post-Knox unconformity provides the principal trapping conditions for underground gas storage at Unionport in Randolph County. Erosion remnants of the porous Knox Dolomite protrude upward into the overlying impermeable Black River Limestone. Although the unconformity has long been recognized in Indiana, data for detailed mapping of its surface are lacking except at Unionport. Here about 50 wells drilled to the Knox outline a surface of steep-sided, ovate erosion remnants of limited lateral extent with vertical relief of about 150 feet. No drainage pattern is evident. The unconformity is postulated to have been developed in an arid environment with wind as the primary erosion agent. The erosion-induced irregularity of the post-Knox unconformity is only slightly reflected on the top of the Trenton Limestone. The composite thickness from the top of the Trenton to the top of the Knox ranges from 400 to 530 feet at the Unionport gas-storage project. Petroleum has been produced in Indiana, Ohio, Kentucky, and southern Ontario from erosion remnants associated with the post-Knox unconformity. We feel that petroleum deposits under similar geologic conditions exist in Indiana and that the crestal area of the Cincinnati Arch provides the most favorable general area for exploration.
Keller, S. J., Abdulkareem, T. F. 1980, Post-Knox unconformity—significance at Unionport gas-storage project and relationship to petroleum exploration in Indiana: Indiana Geological Survey Occasional Paper 31, 19 p., 10 fig.
You may also like:
Can't find what you're looking for? Feel free to contact us directly:
Publication Sales Office
Indiana Geological and Water Survey
420 N. Walnut St.
Bloomington, IN 47404
IGS Return Policy
All sales are final. Materials may not be returned after they have been accepted by the customer. Any discrepencies in mail orders must be reported to IGWS within 10 days of receipt of order.
The Indiana Geological and Water Survey will refund the purchase price and sales tax of products if returned with the original sales receipt within 10 days of receipt of order. Refunds will be issued with the same method of payment as indicated on the original receipt except for cash purchases, which will be refunded by check. Items must be returned in the same condition as purchased. Refunds on digital products and services are not allowed, except for defective media such as CD-ROMs, flash drives, and so on. The customer is responsible for paying shipping costs to return items.