Distribution patterns of facies, radiolarians, and conodonts in the Mississippian to Jurassic siliceous rocks of the northern Brooks Range, Alaska

Mississippian to Jurassic fine-grained siliceous rocks in the northern Brooks Range of Alaska constitute one of the longest known records of continuous deposition of siliceous pelagic and hemipelagic sediments in the world. These rocks include bedded chert, siliceous argillite, siliceous fine-grained limestone, and black carbonaceous shale. They crop out within an east-trending thrust and fold belt more than 1100 km long. The purpose of this chapter is twofold: (1) to document localities in which siliceous fine-grained facies have been dated by means of radiolarians or conodonts and (2) to examine the temporal and spatial distribution patterns of the microfossil faunas and their associated lithofacies. Because of the large number of samples collected for dating during the mapping of the National Petroleum Reserve in Alaska (NPRA) and adjacent areas, the northern Brooks Range samples constitute the largest data base available in the Cordillera for examining relations between the biofacies and lithofacies of chert and associated rocks.