Tectonic environment of Precambrian quartz-pebble conglomerate uranium deposits formed along the southern margin of the Archean Shield in North America

Uraniferous Early Proterozoic conglomerates have been discovered at several localities in Canada and the United States near the southeastern edge of the Archean Superior and Wyoming Provinces. Sedimentary successions that contain the uraniferous conglomerates apparently were deposited in fault-bounded troughs or basins and on faulted coastal plains that formed on or near the margin of an Archean craton or cratons. The Early Proterozoic history of this cratonal margin, called the Proterozoic-Archean boundary zone, is characterized by approximately synchronous periods of (1) extensional tectonics with rifting, volcanism, and subsidence; (2) intrusion of mafic dikes and sills; (3) carbonate shelf development; (4) eugeoclinal sedimentation and volcanism; and (5) orogeny. (author). 47 refs, 4 figs, 4 tabs