Westward-Derived Conglomerates in Moenkopi Formation of Southeastern California, and Their Probable Tectonic Significance

ABSTRACT The upper part of the Moenkopi Formation in the northern Clark Mountains, southeastern California, contains conglomerate beds whose clasts comprise igneous, metamorphic, and sedimentary rocks. Metamorphic clasts include foliated granite, meta-arkose, and quartzite, probably derived from older Precambrian basement and younger Precambrian clastic rocks. Volcanic clasts are altered plagioclase-bearing rocks, and sedimentary clasts were derived from Paleozoic miogeoclinal rocks. Paleocurrent data indicate that the clasts had a source to the southwest. An age of late Early or early Middle Triassic has been tentatively assigned to these conglomerates. These conglomerates indicate that Late Permian to Early Triassic deformational events in this part of the orogen affected rocks much farther east than has been previously recognized.