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The AAPG/Datapages Combined Publications Database

AAPG Bulletin


Volume: 32 (1948)

Issue: 8. (August)

First Page: 1397

Last Page: 1416

Title: Summary of Middle Ordovician Bordering Allegheny Synclinorium

Author(s): Marshall Kay (2)


The Middle Ordovician is divided into the Chazyan, Bolarian, and Trentonian series. The lower Chazyan Blackford and Five Oaks formations and equivalents probably underlie much of the synclinorium; the higher, Lincolnshire, seems limited to the southeastern border. The lower Bolarian Hatterian subseries is also extensive, thins northward by overlap and convergence; the succeeding Hunterian contrasts in thickening northwestward by divergence and addition of younger beds beneath a regional unconformity. The lower Trentonian has belts of differing facies in the south, and thins southeastward along the southeastern margin of the synclinorium. The middle Trentonian is limestone beneath and along the eastern margin, and becomes principally argillite farther southeast. The upper rentonian stratigraphy has been studied only in the northeast.

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