New Sr, Nd, and Pb isotopic data from plutons in the northern Great Basin: Implications for crustal structure and granite petrogenesis in the hinterland of the Sevier thrust belt

Journal Article · Wed May 01 04:00:00 EDT 1991 · Geology; (USA)

DOI:https://doi.org/10.1130/0091-7613(1991)019<0457:NSNAPI>2.3.CO;2· OSTI ID:5470362

Wright, J E ^[1]; Wooden, J L ^[2]

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1. Rice Univ., Houston, TX (USA)
2. Geological Survey, Menlo Park, CA (USA)

The influence of tectonic setting and age on the variation of isotopic signatures of granitic plutons in the northern Great Basin has, in general, not been apparent from previous investigations. None of these studies revealed the remarkable correlation shown by this expanded Sr, Nd, and Pb isotopic data base. Jurassic-Early Cretaceous plutons in the northern Great Basin have a limited range of Sr and Nd isotopic values that cluster near bulk earth. Construction of Sr 0.706 and {epsilon}{sub Nd} = {minus}7 isotopic boundaries is virtually impossible for plutons of this age range. In contrast, Upper Cretaceous peraluminous granites east of the {epsilon}{sub Nd} = {minus}7 line have very negative {epsilon}{sub Nd} values and high initial Sr ratios, and they appear to represent essentially pure crustal melts. The data favor a model that equates generation of these plutons via crustal thickening associated with the Sevier thrust belt. Cenozoic plutons appear to be mixtures of mantle and crustal reservoirs, and their isotopic systematics, along with those of the Late Cretaceous age plutonic suite, define a previously unrecognized, approximately east-west-trending crustal boundary between predominantly Archean crust to the north and predominantly Proterozoic crust to the south. The isotopic data from the Jurassic-Early Cretaceous plutonic suite do not reflect the presence of this boundary, suggesting that the isotopic systematics of this plutonic suite may not have been controlled by the same variations in crustal and/or mantle lithospheric structure at depth.

• OSTI ID: 5470362
• Journal Information: Geology; (USA), Journal Name: Geology; (USA) Vol. 19:5; ISSN GLGYB; ISSN 0091-7613
• Country of Publication: United States
• Language: English

Related Subjects

58 GEOSCIENCES
580000* -- Geosciences
AGE ESTIMATION
ALKALINE EARTH ISOTOPES
BOUNDARY LAYERS
CENOZOIC ERA
CONTINENTAL CRUST
CRETACEOUS PERIOD
DEVELOPED COUNTRIES
DIMENSIONS
EARTH CRUST
EARTH MANTLE
GEOLOGIC AGES
GEOLOGIC FORMATIONS
GEOLOGIC MODELS
GEOLOGIC STRUCTURES
GRANITES
GREAT BASIN
IGNEOUS ROCKS
ISOTOPE RATIO
ISOTOPES
JURASSIC PERIOD
LAYERS
LEAD ISOTOPES
MESOZOIC ERA
NEODYMIUM ISOTOPES
NORTH AMERICA
PETROGENESIS
PLUTONIC ROCKS
PRECAMBRIAN ERA
ROCKS
STRONTIUM ISOTOPES
TECTONICS
THICKNESS
USA