Identification of 2. 0 to 2. 4 Ga Nd model age crustal material in the Cheyenne belt, southeastern Wyoming: Implications for Proterozoic accretionary tectonics at the southern margin of the Wyoming craton

Journal Article · Mon Apr 01 00:00:00 EST 1991 · Geology; (USA)

DOI:https://doi.org/10.1130/0091-7613(1991)019<0360:IOTGNM>2.3.CO;2· OSTI ID:5611174

Ball, T T; Farmer, G L ^[1]

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1. Univ. of Colorado, Boulder (USA)

A detailed survey was conducted of the Nd-isotope compositions of Precambrian metamorphic rocks both within and adjacent to the Cheyenne belt, a metamorphosed crustal segment in southeastern Wyoming that defines the Proterozoic suture zone between the Archean Wyoming craton and accreted Proterozoic island arc(s). The results of the study indicate that Proterozoic miogeoclinal sedimentary rocks exposed north of the Cheyenne belt and deposited at the southern margin of the Wyoming craton contain only Archean crust derived material and no detritus from Proterozoic island arcs approaching from the south. Similarly, Proterozoic crust exposed south of the Cheyenne belt contains no crustal material derived from Archean sources. However, within the Cheyenne belt, paragneiss of the Barber Lake block has 2.0 to 2.4 Ga Nd model ages and is interpreted as metamorphosed intermixed sedimentary detritus from both Archean and Proterozoic sources. The paragneiss is thought to represent remnants of oceanic trench or foredeep sediments deposited in close proximity to both the Archean craton and the Proterozoic island arcs, similar to sedimentary rocks with 2.0 to 2.4 Ga Nd model ages exposed in the Penokean orogen in Wisconsin. The overall lack of 2.0 to 2.4 Ga modal age crustal material in the vicinity of the Cheyenne belt may reflect the fact that much of this crustal material was overthrust onto the Wyoming craton during accretion and then eroded during postorogenic rebound of the continental margin.

• OSTI ID: 5611174
• Journal Information: Geology; (USA), Vol. 19:4; ISSN 0091-7613
• Country of Publication: United States
• Language: English

Related Subjects

58 GEOSCIENCES
CONTINENTAL CRUST
DETECTION
GEOLOGIC FORMATIONS
TECTONICS
WYOMING
AGE ESTIMATION
COMPARATIVE EVALUATIONS
CONTINENTAL MARGIN
EROSION
GEOLOGIC HISTORY
GEOLOGIC STRUCTURES
GEOLOGY
ISOTOPE DATING
METAMORPHIC ROCKS
NEODYMIUM ISOTOPES
OCEANIC CRUST
PRECAMBRIAN ERA
SEDIMENTARY ROCKS
SOURCE ROCKS
WISCONSIN
DEVELOPED COUNTRIES
EARTH CRUST
FEDERAL REGION V
FEDERAL REGION VIII
GEOLOGIC AGES
NORTH AMERICA
ROCKS
USA
580000* - Geosciences