Upper Precambrian (?) Diamictite of Florida Mountains, Southwestern New Mexico

Abstract

Diamictite in the Florida Mountains is about 12 m thick, is probably of younger Precambrian age, and consists of igneous and sedimentary clasts as much as 1.2 m in diameter in a fissile shale matrix. The lower 9 m probably formed from ice-rafted pebbles, cobbles, and boulders that were dropped into marine mud. The clasts were not locally derived, as they consist of rock types not present in the older Precambrian rocks of the Florida Mountains. The upper 3 m appears to be a conglomeratic arkose derived locally after faulting of the lower part of the diamictite.