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Title: Provenance of the Bonner Formation (Belt Supergroup), Montana: Insights from U-Pb and Sm-Nd analyses of detrital minerals

Abstract

Individual detrital monazite grains from the Bonner Formation of the Belt Supergroup in southwestern Montana have been analyzed using U-Pb and Sm-Nd isotopes. Combined with single-grain U-Pb analyses of detrital zircon, these data place constraints on the age and isotopic characteristics of the source area, previously inferred to be the west and south of the Belt basin. U-Pb ages from eight single zircon grains range from 1.70 to 1.86 Ga; two grains were ca. 2.6 Ga. U-Pb ages from five monazite grains range from 1.64 to 1.79 Ga. Sm-Nd analyses of these same monazite grains yield {epsilon}{sub Nd} at the time of crystallization of +0.7 to {minus}14.5. These data suggest that the source area for this part of the Bonner Formation was an Early Proterozoic magmatic (orogenic ) belt with some reworked Archean material. It is postulated that this source area may have been the western edge of Archean crust (Wyoming craton) that was involved in younger magmatism, possibly continuous with rocks of similar age in south-central Montana, the subsurface of Alberta, or the southwestern United States.

Authors:
 [1]; ;  [2]
  1. (Geological Survey of Canada, Calgary, Alberta (Canada))
  2. (Geological Survey of Canada, Ottawa, Ontario (Canada))
Publication Date:
OSTI Identifier:
5524197
Resource Type:
Journal Article
Journal Name:
Geology; (USA)
Additional Journal Information:
Journal Volume: 19:4; Journal ID: ISSN 0091-7613
Country of Publication:
United States
Language:
English
Subject:
58 GEOSCIENCES; GEOLOGIC FORMATIONS; AGE ESTIMATION; ORIGIN; MONTANA; ALBERTA; CARBONATE ROCKS; CONTINENTAL CRUST; CRYSTALLIZATION; ISOTOPE DATING; ISOTOPE RATIO; LEAD ISOTOPES; MAGMATISM; MONAZITES; NEODYMIUM ISOTOPES; SAMARIUM ISOTOPES; SOURCE ROCKS; STRATIGRAPHY; URANIUM ISOTOPES; WYOMING; ZIRCON; ACTINIDE COMPOUNDS; ACTINIDE ISOTOPES; CANADA; DEVELOPED COUNTRIES; EARTH CRUST; FEDERAL REGION VIII; GEOLOGY; ISOTOPES; MATERIALS; MINERALS; NORTH AMERICA; OXYGEN COMPOUNDS; PHASE TRANSFORMATIONS; PHOSPHATES; PHOSPHORUS COMPOUNDS; RADIOACTIVE MATERIALS; RADIOACTIVE MINERALS; RARE EARTH COMPOUNDS; RARE EARTH ISOTOPES; ROCKS; SEDIMENTARY ROCKS; SILICATE MINERALS; SILICATES; SILICON COMPOUNDS; THORIUM COMPOUNDS; THORIUM MINERALS; THORIUM PHOSPHATES; TRANSITION ELEMENT COMPOUNDS; USA; ZIRCONIUM COMPOUNDS; ZIRCONIUM SILICATES; 580000* - Geosciences

Citation Formats

Ross, G.M., Parrish, R.R., and Dudas, F.O. Provenance of the Bonner Formation (Belt Supergroup), Montana: Insights from U-Pb and Sm-Nd analyses of detrital minerals. United States: N. p., 1991. Web. doi:10.1130/0091-7613(1991)019<0340:POTBFB>2.3.CO;2.
Ross, G.M., Parrish, R.R., & Dudas, F.O. Provenance of the Bonner Formation (Belt Supergroup), Montana: Insights from U-Pb and Sm-Nd analyses of detrital minerals. United States. doi:10.1130/0091-7613(1991)019<0340:POTBFB>2.3.CO;2.
Ross, G.M., Parrish, R.R., and Dudas, F.O. Mon . "Provenance of the Bonner Formation (Belt Supergroup), Montana: Insights from U-Pb and Sm-Nd analyses of detrital minerals". United States. doi:10.1130/0091-7613(1991)019<0340:POTBFB>2.3.CO;2.
@article{osti_5524197,
title = {Provenance of the Bonner Formation (Belt Supergroup), Montana: Insights from U-Pb and Sm-Nd analyses of detrital minerals},
author = {Ross, G.M. and Parrish, R.R. and Dudas, F.O.},
abstractNote = {Individual detrital monazite grains from the Bonner Formation of the Belt Supergroup in southwestern Montana have been analyzed using U-Pb and Sm-Nd isotopes. Combined with single-grain U-Pb analyses of detrital zircon, these data place constraints on the age and isotopic characteristics of the source area, previously inferred to be the west and south of the Belt basin. U-Pb ages from eight single zircon grains range from 1.70 to 1.86 Ga; two grains were ca. 2.6 Ga. U-Pb ages from five monazite grains range from 1.64 to 1.79 Ga. Sm-Nd analyses of these same monazite grains yield {epsilon}{sub Nd} at the time of crystallization of +0.7 to {minus}14.5. These data suggest that the source area for this part of the Bonner Formation was an Early Proterozoic magmatic (orogenic ) belt with some reworked Archean material. It is postulated that this source area may have been the western edge of Archean crust (Wyoming craton) that was involved in younger magmatism, possibly continuous with rocks of similar age in south-central Montana, the subsurface of Alberta, or the southwestern United States.},
doi = {10.1130/0091-7613(1991)019<0340:POTBFB>2.3.CO;2},
journal = {Geology; (USA)},
issn = {0091-7613},
number = ,
volume = 19:4,
place = {United States},
year = {1991},
month = {4}
}