Precambrian-Paleozoic Contact in Two Wells in Northwestern Kansas

Abstract

In two well cores from northwestern Kansas a basal Paleozoic sandstone, feldspathic in part, was found to be in sharp, unconformable contact with underlying Precambrian rocks. The source for part of the clastics of the basal Paleozoic sequence was nearby weathered Precambrian rocks. Altered Precambrian gneissic granite is penetrated in one well and Precambrian quartzo-feldspathic schist in the other well. Evidence is lacking to demonstrate a metamorphic rather than an igneous origin for the gneissic granite. The schist is of the almandine-amphibolite metamorphic facies. The potassium-argon ratio from the schist indicates an age of 1.24 billion years.