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U-Pb geochronology of detrital zircon from Upper Jurassic synorogenic turbidites, Galice Formation, and related rocks, western Klamath Mountains: Correlation and Klamath Mountains provenance

Miller, M. Meghan and Saleeby, Jason B. (1995) U-Pb geochronology of detrital zircon from Upper Jurassic synorogenic turbidites, Galice Formation, and related rocks, western Klamath Mountains: Correlation and Klamath Mountains provenance. Journal of Geophysical Research B, 100 (B9). pp. 18045-18058. ISSN 0148-0227. doi:10.1029/95JB00761. https://resolver.caltech.edu/CaltechAUTHORS:20140827-140739118

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Abstract

Synorogenic turbidites of the Upper Jurassic Galice Formation overlie a variety of basement terranes within the western Klamath Mountains along the Oregon-California border, including the early Late Jurassic ophiolite assemblages, ensimatic arc deposits, and sedimentary terranes. U-Pb analyses of 68 multiple grain fractions from 11 samples of detrital zircon support the correlation of Galice Formation on these various basement terranes, although some new complexities in provenance are revealed. With one exception, upper intercept ages range from 1509^(+3)_(-3) to 1675^(+8)_(-8) Ma. Least squares regression of all fractions yields an upper intercept age of 1583±1 Ma, indicating the importance of an ultimately continental, recycled, and generally well-mixed sedimentary source. Early Mesozoic lower intercept ages range between 183^(+2)_(-2) and 263^(+4)_(-3) and average 215±1 Ma. Results from Galice cover on sedimentary basement show significantly older 2.1 Ga Precambrian component, however, that may be locally derived from pre-Late Jurassic basement rocks that are rich in recycled sedimentary debris. Existing isotopic data from older, zircon-bearing Klamath units further indicate that Galice detritus was derived from immediate source terranes within the Klamath Mountains. Reworking of fragile limestone clasts from the biogeographically distinctive eastern Klamath terrane (McCloud Limestone) into Galice Formation substrate also supports early paleogeographic ties between terranes. Thus the tectonic setting of the Late Jurassic Nevadan orogeny in the Klamath Mountains is tightly constrained by original paleogeographic ties between subterranes of the western belt and by provenance ties to terranes to the east. Ultimately continent-derived clastic debris and other distinctive tracers were recycled within this long-lived ensimatic convergent margin system.


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Additional Information:© 1995 American Geophysical Union. Received July 12, 1994; revised January 30, 1995; accepted February 28, 1995. Paper number 95JB00761. IBM and the Division of Geological and Planetary Sciences, California Institute of Technology are gratefully acknowledged for supporting Miller on this project. Laboratory work was supported by National Science Foundation grant EAR 87-08266. Greg Harper guided Miller through some of the secrets of Western Klamath terrane geology. Jim Wright has sparked Miller's interest in Klamath Mountains geology in general and in this project in particular. His ideas and his direction to important localities are gratefully acknowledged. Art Snoke, Sandra Wyld, and Doug Yule are also gratefully acknowledged for discussions and insight. Carol Dupuis corrected the data tables and Gerda Smeltzer and Carrie Whitehill assisted with finalizingt he figures. Jim Wright and Gary Ernst provided helpful reviews.
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Funding AgencyGrant Number
IBMUNSPECIFIED
Caltech Division of Geological and Planetary SciencesUNSPECIFIED
NSFEAR 87-08266
Issue or Number:B9
DOI:10.1029/95JB00761
Record Number:CaltechAUTHORS:20140827-140739118
Persistent URL:https://resolver.caltech.edu/CaltechAUTHORS:20140827-140739118
Official Citation:Miller, M. M., and J. B. Saleeby (1995), U-Pb geochronology of detrital zircon from Upper Jurassic synorogenic turbidites, Galice Formation, and related rocks, western Klamath Mountains: Correlation and Klamath Mountains provenance, J. Geophys. Res., 100(B9), 18045–18058, doi:10.1029/95JB00761.
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:49000
Collection:CaltechAUTHORS
Deposited By: Jason Perez
Deposited On:28 Aug 2014 17:34
Last Modified:10 Nov 2021 18:38

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