Preliminary Report on Some Pennsylvanian Reefs from Northwest Ellesmere Island: ABSTRACT

Abstract

Pennsylvanian reefs as thick as 2,000 feet crop out nearly 10 miles along strike at Hare Fiord, Northwest Ellesmere Island. The reef flanks slope as much as 45°. There is no interfingering between the reefs and the overlying silty limestones. Stratification within the reefs is confined to planes parallel with the reef sides. In order of relative abundance, the reef fauna consists of crinoids, brachiopods, bryozoa, corals, gastropods, ammonites, trilobites, and fusulinids. Fenestellid bryozoans may have provided a reef framework, but no clear zonation into reef barrier and lagoon is apparent. A fore-reef is present, characterized by reef-derived conglomerates. A strange internal conglomerate, not readily explained as solution-breccia, is common. Recrystallization is widespread, particularly along intrusive dike margins. Porosity of the main reef rock is low, but the conditions leading to the formation of internal conglomerate may have produced porous localities in parts of the reef area other than the accessible cross section. The reefs probably formed in a climate not only warmer but also with more sunlight hours than that at the present latitude of northern Ellesmere Island. End_of_Article - Last_Page 518------------