Deposits of low and medium grade phosphate rock were found recently at seven localities on the Arctic slope of Alaska. They were reported by field parties of the U.S. Geological Survey during the mapping of Naval Petroleum Reserve No. 4 and adjacent areas. The deposits are sedimentary in origin and are confined to a thin zone in the Lisburne group of Mississippian age. Six of the localities are in a narrow belt along the north front of the Brooks gang between the Anaktuvuk and Okokmilaga rivers. The seventh is near the Ipnavik River about 100 miles northwest of the Okokmilaga River. At all but two of these localities the zone of soft phosphatic rocks does not crop out extensively and samples of phosphate rock were collected chiefly from float or talus. Little or nothing is known about the thickness and extent of the deposits. Near Chandler Lake on the upper Kiruktagiak River and 11 miles west of at the head of Tiglukpuk Creek, the phosphatic zone is well-exposed. This paper is a preliminary report on the results of a detailed examination of the phosphatic zone in these two areas during the summer of 1953.
