U-Pb isotope geochronologic data from 23 igneous rock units in cental and southeastern Arizona

Spencer, J.E.; Isachsen, C.E.; Ferguson, C.A.; Richard, S.M.; Skotnicki, S.J.; Wooden, J.; Riggs, N.R.

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Spencer, J.E., Isachsen, C.E., Ferguson, C.A., Richard, S.M., Skotnicki, S.J., Wooden, J., and Riggs, N.R., 2003, U-Pb isotope geochronologic data from 23 igneous rock units in cental and southeastern Arizona. Arizona Geological Survey Open File Report, OFR-03-08, 40 p.

Description

Geochronologic analyses of igneous rocks were done over the past several years as part of the joint State-Federal STATEMAP program. These analyses were done to determine the age of rocks in areas where Arizona Geological Survey geologists were making geologic maps at 1 :24,000 scale or compiling geologic maps at 1: 100,000 scale. Geochronologic analyses are a basic component of geologic map making in areas where igneous rocks are present but their ages are poorly known. Most ofthe dates reported here are the result of laboratory analyses by Clark Isachsen at the University of Arizona Department of Geosciences, and were determined in most cases by analysis of single zircon crystals from the rock samples. Two dates were produced at the US Geological Survey in Menlo Park, California, by Joe Wooden, and two are from samples collected by Nancy Riggs and analyzed at UC Santa Barbara. These analyses used multiple zircon crystals divided into size fractions for each laboratory analysis. Sample locations and descriptions are reported in Table 1, and basic geochronologic results are reported in Table 2. Concordia diagrams and analytical data are given in Appendix A. ( 40 pages)

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http://hdl.handle.net/10150/630033

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https://library.azgs.arizona.edu/

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Series/Report no.

OFR-03-08

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Documents in the AZGS Document Repository collection are made available by the Arizona Geological Survey (AZGS) and the University Libraries at the University of Arizona. For more information about items in this collection, please contact azgs-info@email.arizona.edu.

North Bounding Coordinate

34.2708

South Bounding Coordinate

31.3536

West Bounding Coordinate

-112.566

East Bounding Coordinate

-109.05

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AZGS Document Repository