Paleontology and Paleoecology of Wann Formation, Northeastern Oklahoma: ABSTRACT

Abstract

The Wann Formation (Missourian) of northeastern Oklahoma is primarily a regressive marine sequence of calcareous shale, shale, and sandstone with a characteristic molluscan fauna traceable along much of the outcrop. The replacement of a crinoid-brachiopod fauna by the molluscan fauna in Washington County End_Page 540------------------------------ reflects the change from deeper water to a nearshore marine environment. This environmental change was caused by the northward expansion of a deltaic area which generally was on the south. The deltaic sediments are well developed in the southern outcrops of the Wann. The rich molluscan fauna, a Drum-type assemblage, is similar to those found in other Middle and Upper Pennsylvanian formations in Oklahoma indicating a repetition of environments. Trepospira, Worthena, Euphemites, and Glabrocingulum are the predominant elements of the fauna although other gastropods and pelecypods are prominent locally. The relative abundance of a species at any location within the assemblage zone appears to be depth controlled. End_of_Article - Last_Page 541------------