Skip to main content
U.S. flag

An official website of the United States government

U-Pb zircon data for: The Poncha Pass and Deadman Creek areas, northern Sangre de Cristo mountains of south-central Colorado

July 29, 2019

Geologic mapping, characterization of geologic structures, and sampling for geochronology was completed in two areas of the northwestern Sangre de Cristo mountains from 2011 through 2017. This data release provides the raw analytical data, metadata and sample information for 20 zircon U-Pb age analyses from laser ablation-inductively coupled plasma mass spectrometry (LA-ICPMS). The two areas include the Poncha Pass area where the entire 71/2' Poncha Pass quadrangle and parts of five other quadrangles (Mount Ouray, Maysville, Salida West, Salida East, and Wellsville) were mapped at a scale of 1:24,000 (see Minor and others, 2019). The Deadman thrust fault is the second area, approximately 80 km southwest of the Poncha Pass area, and has been preliminarily mapped at a scale of 1:2,000. Ten new U-Pb ages were determined for each area and include Proterozoic metavolcanic, metasedimentary, and metaigneous rocks as well as non-metamorphosed felsic intrusive rocks of upper Mesozoic-Cenozoic age in the Poncha area. Rocks dated in the Deadman area include Proterozoic basement rocks, detrital zircons in Paleozoic sedimentary rocks, and Mesozoic- Cenozoic felsic intrusive rocks. Minor, S.A., Caine, J.S., Ruleman, C.A., Fridrich, C.J., Chan, C.F., Brandt, T.R., Holm- Denoma, C.S., Morgan, L.E., Cosca, M.A., and Grauch, V.J.S., 2019, Geologic Map of the Poncha Pass Area, Chaffee, Fremont, and Saguache Counties, Colorado: U.S. Geological Survey Scientific Investigations Map 3436, 3 sheets, scale 1:24,000, https://doi.org/10.3133/sim3436