Arc plutonism following regional thrusting: Petrology and geochemistry of syn- and post-Nevadan plutons in the Siskiyou Mountains, Klamath Mountains province, California

Barnes, Calvin G.; Snoke, Arthur W.; Harper, Gregory D.; Frost, Carol D.; McFadden, Rory R.; Bushey, Jonathan C.; Barnes, Melanie A.

doi:10.1130/2006.2410(17)

Cited by 13 publications

(22 citation statements)

References 45 publications

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“…Accretion of the outboard Wallowa terrane prior to 160 Ma is consistent with pre-Late Jurassic accretion in all major Paleozoic-Mesozoic terranes of the western United States. In the Klamath Mountains, widespread Middle Jurassic plutons of the Wooley Creek suite stitch previously accreted pre-Late Jurassic terranes and indicate that any ocean basin that lay between the western US plate margin and offshore Triassic-Jurassic island arcs had closed by the end of Middle Jurassic time (e.g., Wright and Fahan 1988;Wright and Wyld 1994;Allen and Barnes 2006;Barnes et al 2006;Dickinson 2008;Ernst et al 2008;Ernst 2015). Although accretion timing may be more ambiguous in the Sierra Nevada on the basis of the ages of stitching plutons (see the review in Dickinson 2008), numerous interpretations suggest that accretion was complete by the end of Middle Jurassic time (e.g., Dilek et al 1988;Sharp 1988;Dilek 1989;Edelman and Sharp 1989;Herzig and Sharp 1992;Girty et al 1995;Miller and Saleeby 1995;Godfrey and Dilek 2000;Snow and Scherer 2006;Snow 2007).…”

Section: Discussionmentioning

confidence: 99%

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Westward Growth of Laurentia by Pre–Late Jurassic Terrane Accretion, Eastern Oregon and Western Idaho, United States

LaMaskin

Dorsey

Vervoort

et al. 2015

The Journal of Geology

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Nd data from the Blue Mountains province, eastern Oregon and western Idaho, clarify terrane correlations and regional evolution of the western Laurentian plate margin during Mesozoic time. We report an Early Jurassic age for a red tuff unit at Pittsburg Landing, Idaho, which is 25 m.yr. older than previous Middle Jurassic estimates. In the Coon Hollow Formation at Pittsburg Landing and at the type location on the Snake River, chemical abrasion thermal ionization mass spectrometry U-Pb zircon ages on interbedded tuff and detrital zircon U-Pb maximum depositional ages indicate that deposition spanned ca. 160-150 Ma, entirely during Late Jurassic time. Detrital zircon U-Pb ages represent local Wallowa arc basement and regional magmatic sources spanning ca. 290-140 Ma. Mudrock Nd isotope compositions of the Coon Hollow Formation record an increase in juvenile magmatism consistent with regional Late Jurassic trends in western North American magmatic systems. These data show that the Coon Hollow Formation is not part of a Middle Jurassic overlap assemblage, as has been historically interpreted. Instead, we propose that the Coon Hollow Formation is part of a belt of suprasubduction-zone extensional back-arc basins that formed in latest Jurassic time due to a well-documented period of trench retreat in the western United States. Our new data require that the underlying Wallowa terrane was accreted to and received detritus from western North America by ca. 160 Ma (early Late Jurassic). This minimum estimate for the age of terrane accretion in western Idaho and eastern Oregon is substantially earlier than previous estimates (∼135-118 Ma). In the Blue Mountains region, westward expansion of Laurentia was accomplished by accretion of arc terranes to the North American craton prior to Late Jurassic time.

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Section: Discussionmentioning

confidence: 99%

“…By 165-160 Ma, arc accretion had ended in all major terranes of the western United States (Harper and Wright 1984;Coleman et al 1988;Wright and Fahan 1988;Hacker et al 1995;Barnes et al 2006;Dorsey and LaMaskin 2007), and a period of postaccretionary subduction and extensional trench retreat began ca. 160-155 Ma ( fig.…”

Section: Discussionmentioning

confidence: 99%

Westward Growth of Laurentia by Pre–Late Jurassic Terrane Accretion, Eastern Oregon and Western Idaho, United States

LaMaskin

Dorsey

Vervoort

et al. 2015

The Journal of Geology

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“…153-150 Ma;Harper and Wright, 1984;Chamberlain et al, 2006), and an important Middle Jurassic orogeny has been referred to as the Siskiyou orogeny (ca. 169-161 Ma; Coleman et al, 1988;Barnes et al, 2006;Snoke and Barnes, 2006). These regional contractional events were separated by a widespread extensional episode manifested by the development of ophiolitic assemblages (e.g., Preston Peak, Josephine ophiolites: Snoke, 1977;Saleeby et al, 1982;Harper and Wright, 1984;Harper et al, 1994;Snoke and Barnes, 2006).…”

Section: Introductionmentioning

confidence: 91%

Late Jurassic magmatism, metamorphism, and deformation in the Blue Mountains Province, northeast Oregon

Schwartz

Snoke

Cordey

et al. 2011

Geological Society of America Bulletin

100

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International audienceAn early to mid-Mesozoic record of sedimentation, magmatism, and metamorphism is well developed in the Blue Mountains Province of northeast Oregon. Detailed studies-both north and south of the Blue Mountains Province (e. g., terranes of the Intermontane belt, Klamath Mountains, and western Sierra Nevada) have documented a complex Middle to Late Jurassic orogenic evolution. However, the timing of magmatic, metamorphic, and deformational events in the Blue Mountains, and the significance of these events in relationship to other terranes in the western North American Cordillera remain-poorly understood. In this study, we investigate the structural, magmatic, and metamorphic histories of brittle to semibrittle deformation zones that indicate widespread Late Jurassic orogenesis in the Blue Mountains Province. Folding and faulting associated with contractional deformation are primarily localized along terrane boundaries (e. g., Baker-Wallowa and Baker-Izee-Olds Ferry boundaries) and within the composite Baker oceanic melange terrane (e. g., Bourne-Greenhorn subterrane boundary). These brittle to semibrittle deformation zones are broadly characterized by the development of E-W-oriented slaty to spaced cleavage in fine-grained metasedimentary rocks of the Baker terrane (e. g., Elkhorn Ridge Argillite), approximately N-S-bivergent folding, and N- and S-dipping reverse and thrust faulting on opposite flanks of the Baker terrane. Similarly oriented contractional features are also present in late Middle Triassic to early Late Jurassic (i.e., Oxfordian Stage, ca. 159 Ma) sedimentary rocks of the John Day and Huntington areas of northeast Oregon. Radiometric age constraints from youngest detrital zircons in deformed sedimentary rocks and crystallization ages of postkinematic plutons, which intrude the deformation zones, limit deformation to between ca. 159 and ca. 154 Ma. We suggest that the widespread, approximately N-S-directed contractional features in the Blue Mountains Province record a short-lived, intense early Late Jurassic deformational event and preserve an example of upper-crustal strain localization associated with terminal arc-arc collision between the Olds Ferry and Wallowa island-arc terranes. The age interval of deformation in the Blue Mountains Province is younger than Middle Jurassic deformation in the Canadian Cordillera and Klamath Mountains (Siskiyou orogeny) and predates classic Nevadan orogenesi

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“…The amagmatic interval in the Blue Mountains province lasted for ~6 m.y. and was followed by a renewed phase of regionally extensive, high-Sr/Y magmatism that extended from the Blue Mountains in Oregon to the Klamath Mountains in northern California (Barnes et al, 1996(Barnes et al, , 2006Schwartz et al, 2011b).…”

Section: Timing Of Batholith Constructionmentioning

confidence: 99%

Time scales and processes of Cordilleran batholith construction and high-Sr/Y magmatic pulses: Evidence from the Bald Mountain batholith, northeastern Oregon

et al. 2014

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Cordilleran granitic batholiths (sensu lato) preserve information about time scales and processes of upper crustal magmatic arc construction during Mesozoic subduction and mountain building. The Bald Mountain batholith in northeastern Oregon (USA) is a classic example of a composite, incrementally constructed batholith that formed during terrane amalgamation outboard of the western U.S. Cordillera. Whole-rock geochemistry and zircon trace element, U-Pb, Lu-Hf, and O isotopic data reveal that batholith construction occurred over ~15 Ma, commencing with the syncollisional emplacement of small, low-Sr/Y (<40) norite-granite plutons from 157 to 155 Ma. The next phase of magmatism was postcollisional and dominated by high-Sr/Y (>40) tonalite-granodiorite mag matism that produced the main mass of the batholith, including the granodiorite of Anthony Lake (147 Ma) and the tonalite of Bald Mountain (145-141 Ma). Zircons from the norite-granite suite display a narrow range in initial εHf of 7.2-7.7 and elevated δ 18 O (Zrn) ranging from 8.2‰ to 10.0‰ (excluding one outlier). Zircons from the later granodiorite-tonalite suite show a similar range of initial εHf values (6.3-8.9) and δ 18 O (7.1‰-10.0‰), indicating a similar history of interaction with evolved crustal material. Modeling of whole-rock and zircon geochemistry indicates that both the low-and high-Sr/Y magmas composing the main phase of the batholith were generated by dehydration-partial melting of mafi c arc crust (e.g., amphibolite), leaving behind a plagioclase-poor restite, which was garnet granulite in the case of the high-Sr/Y magmas. Final magma compositions in both suites were affected by assimilation of supracrustal material either at depth or during ascent. We suggest that high-Sr/Y magmas in the Bald Mountain batholith were generated by partial melting of thickened arc crust ~10 m.y. after arc-arc collision began at 159-154 Ma. Heat to drive lower crustal melting was conveyed by an increase in mantle power input as a result of renewed subduction-related magmatism. Mixing and homogenization in the lower crust involving mantle-derived basalts and crustally derived partial melts can account for the geochemical variation we observe in tonalites and granodiorites in the Bald Mountain batholith.

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Arc plutonism following regional thrusting: Petrology and geochemistry of syn- and post-Nevadan plutons in the Siskiyou Mountains, Klamath Mountains province, California

Cited by 13 publications

References 45 publications

Westward Growth of Laurentia by Pre–Late Jurassic Terrane Accretion, Eastern Oregon and Western Idaho, United States

Westward Growth of Laurentia by Pre–Late Jurassic Terrane Accretion, Eastern Oregon and Western Idaho, United States

Late Jurassic magmatism, metamorphism, and deformation in the Blue Mountains Province, northeast Oregon

Time scales and processes of Cordilleran batholith construction and high-Sr/Y magmatic pulses: Evidence from the Bald Mountain batholith, northeastern Oregon

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