Carbonatites in the Wet Mountains area, Custer and Fremont Counties, Colorado — Chemical and mineralogical data

Geology and resources of thorium and associated elements in the Wet Mountains area, Fremont and Custer counties, Colorado

“…Replacement carbonatite, Wet Mountains area. Based on 6-step semiquantitative spectrographic and gamma ray spectrometric (RaeU and Th) analyses (Armbrustmacher and Brownfield, 1978). Number of samples -8.…”

“…Carbonatite dikes and irregularly shaped intrusions in and near the McClure Mountain and Gem Park Complexes form two distinct groups, replacement and primary magmatic, as determined chiefly by differences in petrography Armbrustmacher and Brownfield, 1978). Replacement car bonatites show textures indicating pseudomorphous replacement of an originally porphyritic or hypidiomorphic-granular rock by carbonate mineral.…”

“…The replacement carbonatites contain a fairly large variety of minerals, although not as many as the primary magmatic carbonatites (table 2), based on Annbrustmacher (1979) and Armbrustmacher and Brownfield (1978). Calcite/dolomite ratios are variable although calcite is usually more abundant.…”

Alkaline rock complexes in the Wet Mountains area, Custer and Fremont counties, Colorado

“…Majorelement analyses of mafic-ultramafic rocks from the Gem Park Complex are from Parker and Sharp (1970, Armbrustmacher (1979) and Armbrustmacher and Brownfield (1978). Radiometric ages of rocks in the complexes have been reported by Jaffe andothers (1959, p. 127), Fenton andFaure (1970), Olson and Marvin (1971), and Armbrustmacher and Hedge (1982).…”

Thorium resources of selected regions in the United States

“…Staatz and Conklin (1967), and the Goldie carbonatite has been described by Heinrich (1977). A total of 41 mineral species have been identified in the carbonatites, and they are listed in Armbrustmacher and Brownfield (1978). Calcite is ubiquitous, dolomite is very common, and strontianite and ankerite are sparse.…”