Late Precambrian tectonism in the Kingston Range, southern California

Speculation on the early history of the Cordilleran geosyncline of North America has relied in part on interpretation of the tectonic setting of the Precambrian Pahrump Group. Recent mapping in the Kingston Range resulted in new data to aid our speculation. Specifically, Precambrian tectonic events involving folding and later low-angle normal faulting affected the Crystal Spring Formation, Beck Spring Dolomite, and lower part of the Kingston Peak Formation. Unconformably overlying these units is a relatively undeformed conglomerate. Diamictite occurs both above and below the unconformity; hence, Cordilleran-wide correlations of the Kingston Peak Formation based on diamictite require reassessment. The nature of boundaries, localized deformation, and outcrop distribution of the Pahrump Group suggest that these rocks may be preserved in transtensional basins associated with strike-slip faulting, possibly occurring during development of the late Precambrian continental margin. *Present addresses: Walker, Department of Geology, University of Kansas, Lawrence, Kansas 66045; Klepacki, Exxon Production Research Co., P.O. Box 2189, Houston, Texas 77001