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Title: Nd, O and Sr isotopic constraints on the origin of Precambrian rocks, southern Black Hills, South Dakota

Abstract

The Nd, O and Sr isotopic characteristics of Precambrian metasedimentary, metavolcanic and granitic rocks from the Black Hills of South Dakota are examined. Two late-Archean granites (2.5-2.6 Ga) have T/sub DM/ ages of 3.05 and 3.30 Ga, suggesting that at least one of the granites was derived through the melting of significantly older crust. Early-Proterozoic metasedimentary rocks have T/sub DM/ ages that range from 2.32 to 2.45 Ga. These model ages, in conjunction with probable stratigraphic ages ranging from 1.9 to 2.2 Ga, indicate that mantle-derived material was added to the continental crust of this region during the early-Proterozoic. Previous studies of the Harney Peak Granite complex have reported U-Pb and Rb-Sr ages of about 1.71 Ga, and most granite samples examined in this study have Sr isotopic compositions consistent with that age. Two granite samples taken from the same sill, however, give two-point Rb-Sr and Sm-Nd ages of 2.08 +/- 0.08 and 2.20 +/- 0.20 Ga, respectively. In addition, whole-rock and apatite samples of the spatially associated Tin Mountain pegmatite give a Sm-Nd isochron age of 2000 +/- 100 Ma.

Authors:
; ; ;
Publication Date:
Research Org.:
State Univ. of New York, Stony Brook
OSTI Identifier:
6691580
Alternate Identifier(s):
OSTI ID: 6691580
DOE Contract Number:  
AC02-79ER10412; AS03-82ER12040; FG01-84ER13259
Resource Type:
Journal Article
Journal Name:
Geochim. Cosmochim. Acta; (United States)
Additional Journal Information:
Journal Volume: 50:12
Country of Publication:
United States
Language:
English
Subject:
58 GEOSCIENCES; GRANITES; ORIGIN; METAMORPHIC ROCKS; SOUTH DAKOTA; ISOTOPE RATIO; NEODYMIUM ISOTOPES; OXYGEN ISOTOPES; STRONTIUM ISOTOPES; ALKALINE EARTH ISOTOPES; FEDERAL REGION VIII; IGNEOUS ROCKS; ISOTOPES; NORTH AMERICA; PLUTONIC ROCKS; ROCKS; USA 580300* -- Mineralogy, Petrology, & Rock Mechanics-- (-1989); 580400 -- Geochemistry-- (-1989)

Citation Formats

Walker, R.J., Hanson, G.N., Papike, J.J., and O'Neil, J.R. Nd, O and Sr isotopic constraints on the origin of Precambrian rocks, southern Black Hills, South Dakota. United States: N. p., 1986. Web. doi:10.1016/0016-7037(86)90230-9.
Walker, R.J., Hanson, G.N., Papike, J.J., & O'Neil, J.R. Nd, O and Sr isotopic constraints on the origin of Precambrian rocks, southern Black Hills, South Dakota. United States. doi:10.1016/0016-7037(86)90230-9.
Walker, R.J., Hanson, G.N., Papike, J.J., and O'Neil, J.R. Mon . "Nd, O and Sr isotopic constraints on the origin of Precambrian rocks, southern Black Hills, South Dakota". United States. doi:10.1016/0016-7037(86)90230-9.
@article{osti_6691580,
title = {Nd, O and Sr isotopic constraints on the origin of Precambrian rocks, southern Black Hills, South Dakota},
author = {Walker, R.J. and Hanson, G.N. and Papike, J.J. and O'Neil, J.R.},
abstractNote = {The Nd, O and Sr isotopic characteristics of Precambrian metasedimentary, metavolcanic and granitic rocks from the Black Hills of South Dakota are examined. Two late-Archean granites (2.5-2.6 Ga) have T/sub DM/ ages of 3.05 and 3.30 Ga, suggesting that at least one of the granites was derived through the melting of significantly older crust. Early-Proterozoic metasedimentary rocks have T/sub DM/ ages that range from 2.32 to 2.45 Ga. These model ages, in conjunction with probable stratigraphic ages ranging from 1.9 to 2.2 Ga, indicate that mantle-derived material was added to the continental crust of this region during the early-Proterozoic. Previous studies of the Harney Peak Granite complex have reported U-Pb and Rb-Sr ages of about 1.71 Ga, and most granite samples examined in this study have Sr isotopic compositions consistent with that age. Two granite samples taken from the same sill, however, give two-point Rb-Sr and Sm-Nd ages of 2.08 +/- 0.08 and 2.20 +/- 0.20 Ga, respectively. In addition, whole-rock and apatite samples of the spatially associated Tin Mountain pegmatite give a Sm-Nd isochron age of 2000 +/- 100 Ma.},
doi = {10.1016/0016-7037(86)90230-9},
journal = {Geochim. Cosmochim. Acta; (United States)},
number = ,
volume = 50:12,
place = {United States},
year = {1986},
month = {12}
}