Descriptions - Federal 1-17R, North Sioux Pass, sec. 17, T26N, R58E, Richland Co., MT
Location: NE NW SEC. 17-T26N-R58E
Interval: RATCLIFFE
Reported Core Interval: 8783-8865
Adjusted Core Interval: 8786-8868
8783-8796.5
Brown to gray, peloidal, skeletal, and algal mudstone to wackestone. Algal fragments are Ortonella nodules and skeletal fragments are sparse crinoids. There is sparse visible porosity and poor oil staining at the base of the unit.
8796.5-8802.5
Black skeletal wackestones and packstones. Skeletal fragments are crinoids and tabulate corals. Deposition was in shallow shelf environments.
8802.5-8809
Brown dolomitic mudstone. Planolites burrow structures are common and there is good visible porosity and oil staining.
8809-8814
Black skeletal mudstones and wackestones. Skeletal fragments are crinoids and brachiopod fragments. Deposition was in shallow shelf environments.
8814-8818
Black to gray laminated mudstone.
8818-8833
Black skeletal mudstones and wackestones. Skeletal fragments are crinoids and brachiopod fragments. The interval is burrowed by Thalassinoides and Planolites. Deposition was in shallow shelf environments.
8833-8837
Black to gray laminated mudstone.
8837-8848
Black to dark brown, skeletal mudstone. Skeletal fragments are sparse crinoids. Planolites burrow structures are common and the unit is slightly dolomitic.
8848-8862
Black skeletal mudstones and wackestones. Skeletal fragments are crinoids and brachiopod fragments. Deposition was in shallow shelf environments.
8862-8865
Black to dark brown, skeletal mudstone. Skeletal fragments are sparse crinoids. Planolites burrow structures are common.