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Title:
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A rift-edge facies of the Late Jurassic Rogue-Chetco Arc and JosephineOphiolite, Klamath Mountains, Oregon
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Reference Number:
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2045
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ISSN:
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0072-1077
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Publication Year:
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2006
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Book Editors:
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Snoke, Arthur W; Barnes, Calvin G
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GeoREF Number:
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2007-028084 (View Original Data File)
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Authors:
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Yule, J Douglas; Saleeby, Jason B; Barnes, Calvin G
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Descriptors:
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California; depositional environment; fabric; Fiddler Mountain;Invertebrata; Josephine Ophiolite; Jurassic; Klamath Mountains;lithofacies; lithosphere; major elements; Mesozoic; metals;microfossils; olistostromes; Onion Camp; Oregon; plate tectonics;Protista; provenance; Radiolaria; rare earths; Rattlesnake CreekTerrane; rifting; Rogue-Chetco Arc; sedimentary structures; softsediment deformation; trace elements; United States; Upper Jurassic
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ISBN:
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0813724104; 978081372410
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Source:
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Special Paper - Geological Society of America, vol.410, pp.53-76,2006
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Abstract:
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The western Jurassic belt of the Klamath Mountains represents one ofthe Earth's best-preserved exposures of ancient marginal ocean basinlithosphere and chiefly consists of the coeval Rogue-Chetcovolcanic-plutonic oceanic arc and Josephine ophiolite. This LateJurassic ocean basin is hypothesized to have formed in response torifting that initiated at ca. 165 Ma along the western margin of NorthAmerica, disrupting a Middle Jurassic arc that had been constructed onolder Klamath terranes and forming a marginal ocean basin with anactive arc, inter-arc basin, and remnant arc. Previous workerscharacterized a rift-edge facies in the remnant-arc region. Thischapter describes field, age, and geochemical data that suggest that asimilar rift-edge facies exists in the vicinity of the active arc, onthe opposite side of the marginal basin. The rift-edge facies in theactive arc setting consists of two main lithotectonic units, hereinnamed informally as the Onion Camp complex and Fiddler Mountainolistostrome. The Onion Camp complex is partly composed of acharacteristic metabasalt and red chert association. Red chert yieldedscarce radiolarians of Triassic(?) and Early Jurassic age. A distinctchert-pebble conglomerate occurs at scarce localities withinmetasedimentary rocks. Concordant, composite bodies of amphibolite andserpentinized peridotite represent another distinctive feature of theOnion Camp complex. The metamorphic and lithologic features of theOnion Camp complex are similar to the lower melange unit of theRattlesnake Creek terrane, and the units are interpreted to becorrelative. The Fiddler Mountain olistostrome is composed of LateJurassic (Kimmeridgian?) pelagic and hemipelagic rocks interlayeredwith ophioliteclast breccia and megabreccia, similar in character toolistostromal deposits associated with the rift-edge facies of theremnant arc. The occurrence of the Rattlesnake Creek terrane and anassociated olistostromal deposit within the western Jurassic belt ofsouthwestern Oregon may therefore represent the rift-edge facies inthe active arc setting, at the transition between the Rogue-Chetco arcand Josephine ophiolite, further corroborating previous models for theLate Jurassic tectonic evolution of the Klamath Mountains.
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Copyright:
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GeoRef, Copyright 2007, American Geological Institute.
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