Authors: Dennis R. Kolata, Warren D. Huff, and Stig M. Bergström
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The Ordovician stratigraphic succession of eastern North America contains at least 60 altered volcanic ash beds, K-bentonites, one or more of which are distributed over an area of 1.5 million square km. Most Ordovician K-bentonites are not widely distributed, but a few can be correlated for hundreds or thousands of kilometers by chemical fingerprinting techniques, tracing on wireline logs, and matching of detailed outcrop descriptions. K-bentonites are a potential source of diverse geologic information. Because the beds were deposited in a geologic instant over large areas, they constitute nearly isochronous rock units useful in precise correlations applicable to biogeographic, paleogeographic, paleoecologic, tectonomagmatic, geochronologic, and sedimentologic investigations in both local and regional scales. A first step in understanding these aspects of Ordovician geologic history is to develop a regional K-bentonite stratigraphy. The authors attempt to 1) summarize the mineralogies and chemical compositions that help distinguish individual beds and provide information regarding the tectonomagmatic setting of the source volcanoes; 2) document the geographic and stratigraphic distribution of the 60 or more Ordovician K-bentonites in eastern North America; 3) determine the relative positions of K-bentonites within an established biostratigraphic framework; and 4) determine which beds or bed complexes have potential event-stratigraphic significance.
Published: 1/03/1997
ISBN Number: 0813723132
Pages: 84
Product Category: Special Papers