Carboniferous Tidal-Flat Deposits of the North Flank, Northeastern Brooks Range, Arctic Alaska

Abstract

In the Sadlerochit Mountains and adjacent areas (Fig. 43-1) the Carboniferous Lisburne Group, some 460 to 640 meters thick, was formed by a two-phase carbonate depositional cycle that began in late Mississippian time with the deposition of the basal Alapah Limestone and continued into Pennsylvanian time, when the Wahoo Limestone was deposited (Fig. 43-2). These carbonate sediments are part of a regional transgressive sequence. In the Sadlerochit Mountains above the Kayak(?) Shale, the basal late Mississippian Alapah limestones typically consist of well-sorted, pelletoidal-bioclastic grainstones and packstones and lesser amounts of ooid grainstones. Overlying these are beds of poorly sorted bryozoan-echinoderm packstones and wackestones. The environment of deposition for these carbonates is interpreted as open platform normal marine.