Reconnaissance geological and mineral resource map of northern Sierra Madre Occidental, Mexico
The northern Sierra Madre Occidental (SMO) map (scale 1:500,000) comprises 305,000 km/sup 2/ in the states of Chihuahau and Sonora. The centrally-located plateau section is divided into an upper, predominantly rhyolitic sequence, overlying an andesite-rich interval, directly correlatable with Tertiary volcanic units in central and southern SMO, respectively (Clark, 1983; 1984). Precambrian rocks occur in both flanks of SMO, either in the subsurface or surface exposures. They are succeeded by Early and Late Paleozoic sedimentary strata in Sonora and by a more discontinuous sequence in western Chihuahua. Mesozoic strata are dominated by Cretaceous carbonate sequences in central Chihuahua, and by late Triassic - Early Jurassic continental and Jurassic magmatic arc deposits in Sonora. Late Mesozoic - Early Cenozoic batholiths were emplaced in numerous localities in Sonora, whereas only isolated granitoid stocks are exposed in Chihuahua. Widespread lavas of basaltic composition are Late Tertiary to Quaternary in age. Late Cenozoic unconsolidated clastic deposits fill basins and constitute the coastal plain on the west. The main mineralizing epoch occurred in Late Cretaceous - Early Tertiary time, is aligned in northwesterly-trending belts and included numerous porphyry (Cu-Mo) deposits, scattered contact metasomatic (Cu-W) ores and a fissure-vein (Ag-Au) assemblage in the western margin; a (Pb-Zn-Ag) assemblage in fissure-veins and manto-chimney deposits, manganese and volcanogenic uranium ores in the eastern flank. Important industrial minerals and rocks include graphite, fluorspar and building materials.
- Research Organization:
- Univ. of Texas, El Paso (USA)
- OSTI ID:
- 6877516
- Report Number(s):
- CONF-8510489-
- Journal Information:
- Geol. Soc. Am., Abstr. Programs; (United States), Vol. 17; Conference: 98. annual meeting of the Geological Society of America, Orlando, FL, USA, 28 Oct 1985
- Country of Publication:
- United States
- Language:
- English
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