Hinterland drainage closure and lake formation in response to middle Eocene Farallon slab removal, Nevada, U.S.A.

Smith, M. Elliot; Cassel, Elizabeth J.; Jicha, Brian R.; Singer, Brad S.; Canada, Andrew S.

doi:10.1016/j.epsl.2017.09.023

Cited by 35 publications

(95 citation statements)

References 67 publications

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“…From the Paleogene to the early Miocene, a chain of metamorphic core complexes formed across the hinterland, from British Columbia to Arizona, some of which brought middle and lower crustal rocks from depths of ~35-40 km to the surface (Armstrong, 1982;Dokka et al, 1986;Hodges et al, 1992;McGrew and Snee, 1994;Henry et al, 2011;Hallett and Spear, 2014). Well-documented thermochronologic trajectories of multiple Cordilleran metamorphic core complexes suggest that initial metamorphic core complex exhumation occurred during the Late Cretaceous and/or Paleogene (Snoke and Miller, 1988;Wright and Snoke, 1993;Wells, 1997;McGrew et al, 2000), potentially aided by the onset of magmatism (MacCready et al, 1997;Bendick and Baldwin, 2009;Smith et al, 2014Smith et al, , 2017Hallett and Spear, 2015). However, this metamorphic core complex record of partial melting, crustal flow, and exhumation is not clearly reflected in the stratigraphic record (Colgan et al, 2010;Lund Snee et al, 2016;Smith et al, 2017;Canada et al, 2019).…”

Section: Research Papermentioning

confidence: 99%

“…Well-documented thermochronologic trajectories of multiple Cordilleran metamorphic core complexes suggest that initial metamorphic core complex exhumation occurred during the Late Cretaceous and/or Paleogene (Snoke and Miller, 1988;Wright and Snoke, 1993;Wells, 1997;McGrew et al, 2000), potentially aided by the onset of magmatism (MacCready et al, 1997;Bendick and Baldwin, 2009;Smith et al, 2014Smith et al, , 2017Hallett and Spear, 2015). However, this metamorphic core complex record of partial melting, crustal flow, and exhumation is not clearly reflected in the stratigraphic record (Colgan et al, 2010;Lund Snee et al, 2016;Smith et al, 2017;Canada et al, 2019). Outside or peripheral to the metamorphic core complexes, existing structural histories of Paleogene hinterland extension also commonly lack a well-preserved complementary stratigraphic record or constraints on the magnitude and/or timing of deformation (e.g., Camilleri and Chamberlain, 1997;Long et al, 2015;Pape et al, 2016).…”

Section: Research Papermentioning

confidence: 99%

“…Deposition of these sediments is interpreted to reflect accommodation formed during 4 km of throw along the Ninemile fault system, but this deformation is broadly attributed to episodic Late Cretaceous-Oligocene extension (Druschke et al, 2009b). To the north, fluvial and lacustrine rocks of the Elko Formation cover a 23,000 km 2 area adjacent to the Ruby Mountains-East Humboldt Range metamorphic core complex (Coats, 1987;Haynes, 2003) but are not unequivocally diagnostic of deposition within an extensional basin (Henry, 2008;Smith et al, 2017). Elko Formation strata are interpreted to be locally tilted 10°-15° to the southeast prior to eruption of ca.…”

Section: Research Papermentioning

confidence: 99%

“…40 Ar/ 39 Ar geochronology of abundant tuffs exposed within Copper Basin ( Fig. 2; e.g., Rahl et al, 2002;Henry et al, 2011;Smith et al, 2017) facilitates basin-wide correlation of strata and depositional age assessment for sediment lag-time calculations.…”

Section: Research Papermentioning

confidence: 99%

“…4; Coats, 1964;Henry, 2008). The age model for these strata integrates new single-crystal sanidine 40 Ar/ 39 Ar geochronology (Henry, 2008;Smith et al, 2017) and legacy biotite 40 Ar/ 39 Ar ages (Rahl et al, 2002) recalculated to the 28.201 Ma age for Fish Canyon Tuff sanidine (Fig. 2;cf.…”

Section: Stratigraphy Of Copper Basinmentioning

confidence: 99%

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Eocene exhumation and extensional basin formation in the Copper Mountains, Nevada, USA

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Within extended orogens, records that reflect the driving processes and dynamics of early extension are often overprinted by subsequent orogenic collapse. The Copper Mountains of northeastern Nevada preserve an exceptional record of hinterland extensional deformation and high-elevation basin formation, but current geochronology and thermochronology are insufficient to relate this to broader structural trends in the region. This extension occurred concurrent with volcanism commonly attributed to Farallon slab removal. We combine thermochronology of both synextensional hanging-wall strata and footwall rocks to comprehensively evaluate the precise timing and style of this deformation. Specifically, we apply (U-Th)/(He-Pb) double dating of minerals extracted from Eocene–Oligocene Copper Basin strata with multi-mineral (U-Th)/He and 40Ar/39Ar thermochronology of rocks sampled across an ∼20 km transect of the Copper Mountains. We integrate basement and detrital thermochronology records to comprehensively evaluate the timing and rates of hinterland extension and basin sedimentation. Cooling and U-Pb crystallization ages show the Coffeepot Stock, which spans the width of the Copper Mountains, was emplaced at ca. 109–108 Ma, and then cooled through the 40Ar/39Ar muscovite and biotite closure temperatures by ca. 90 Ma, the zircon (U-Th)/He closure temperature between ca. 90 and 70 Ma, and the apatite (U-Th)/He closure temperature between 43 and 40 Ma. Detrital apatite and zircon (U-Th)/(He-Pb) double dating of late Eocene fluvial and lacustrine strata of the Dead Horse Formation and early Oligocene fluvial strata of the Meadow Fork Formation, both deposited in Copper Basin, shows that Early Cretaceous age detrital grains have a cooling history that is analogous to proximal intrusive rocks of the Coffeepot Stock. At ca. 38 Ma, cooling and depositional ages for Copper Basin strata reveal rapid exhumation of proximal source terranes (cooling rate of ∼37 °C/m.y.); in these terranes, 8–12 km of slip along the low-angle Copper Creek normal fault exhumed the Coffeepot Stock in the footwall. Late Eocene–early Oligocene slip along this fault and an upper fault splay, the Meadow Fork fault, created a half graben that accommodated ∼1.4 km of volcaniclastic strata, including ∼20 m of lacustrine strata that preserve the renowned Copper Basin flora. Single-crystal sanidine 40Ar/39Ar geochronology of interbedded tuffs in Copper Basin constrains the onset of rapid exhumation to 38.0 ± 0.9 Ma, indicating that surface-breaching extensional deformation was coincident with intense proximal volcanism. Coarse-grained syndeformational sediments of the Oligocene Meadow Fork Formation were deposited just prior to formation of an extensive regional Oligocene–Miocene unconformity and represent one of the most complete hinterland stratigraphic records of this time. We interpret this history of rapid late Eocene exhumation across the Copper Mountains, coeval volcanism, and subsequent unconformity formation to reflect dynamic and thermal effects associated with Farallon slab removal. The final phase of extension is recorded by late, high-angle normal faults that cut and rotate the early middle Miocene Jarbidge Rhyolite sequence, deposited unconformably in the hanging wall. These results provide an independent record of episodic Paleogene to Miocene exhumation documented in Cordilleran metamorphic core complexes and establish that substantial extension occurred locally in the hinterland prior to province-wide Miocene extensional break-up.

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