气候变化领域集成服务门户(CCPortal): Accelerating exhumation in the Eocene North American cordilleran hinterland: Implications from detrital zircon (U-Th)/(He-Pb) double dating

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DOI	10.1130/B35160.1
	Accelerating exhumation in the Eocene North American cordilleran hinterland: Implications from detrital zircon (U-Th)/(He-Pb) double dating
	Canada A.S.; Cassel E.J.; Stockli D.F.; Smith M.E.; Jicha B.R.; Singer B.S.
发表日期	2020
ISSN	167606
起始页码	198
结束页码	214
卷号	132 期号:2021-01-02
英文摘要	Basins in orogenic hinterlands are directly coupled to crustal thickening and extension through landscape processes and preserve records of deformation that are unavailable in footwall rocks. Following prolonged late Mesozoic-early Cenozoic crustal thickening and plateau construction, the hinterland of the Sevier orogen of western North America underwent late Cenozoic extension and formation of metamorphic core complexes. While the North American Cordillera is one of Earth's best-studied orogens, estimates for the spatial and temporal patterns of initial extensional faulting differ greatly and thus limit understanding of potential drivers for deformation. We employed (U-Th)/(He-Pb) double dating of detrital zircon and (U-Th)/He thermochronology of detrital apatite from precisely dated Paleogene terrestrial strata to quantify the timing and magnitude of exhumation and explore the linkages between tectonic unroofing and basin evolution in northeastern Nevada. We determined sediment provenance and lag time evolution (i.e., the time between cooling and deposition, which is a measure of upper-crustal exhumation) during an 8 m.y. time span of deposition within the Eocene Elko Basin. Fluvial strata deposited between 49 and 45 Ma yielded Precambrian (U-Th)/He zircon cooling ages (ZHe) with 105-740 m.y. lag times dominated by unreset detrital ages, suggesting limited exhumation and Proterozoic through early Eocene sediment burial (<4-6 km) across the region. Minimum nonvolcanic detrital ZHe lag times decreased to <100 m.y. in 45-43 Ma strata and to <10 m.y. in 43-41 Ma strata, illustrating progressive and rapid hinterland unroofing in Eocene time. Detrital apatite (U-Th)/He ages present in ca. 44 and 39 Ma strata record Eocene cooling ages with 1-20 m.y. lag times. These data reflect acceleration of basement exhumation rates by >1 km/m.y., indicative of rapid, large-magnitude extensional faulting and metamorphic core complex formation. Contemporaneous with this acceleration of hinterland exhumation, syntectonic freshwater lakes developed in the hanging wall of the Ruby Mountains-East Humboldt Range metamorphic core complex at ca. 43 Ma. Volcanism driven by Farallon slab removal migrated southward across northeastern Nevada, resulting in voluminous rhyolitic eruptions at 41.5 and 40.1 Ma, and marking the abrupt end of fluvial and lacustrine deposition across much of the Elko Basin. Thermal and rheologic weakening of the lithosphere and/or partial slab removal likely initiated extensional deformation, rapidly unroofing deeper crustal levels. We attribute the observed acceleration in exhumation, expansion of sedimentary basins, and migrating volcanism across the middle Eocene to record the thermal and isostatic effects of Farallon slab rollback and subsequent removal of the lowermost mantle lithosphere. © 2019 Geological Society of America.
语种	英语
来源期刊	Bulletin of the Geological Society of America
文献类型	期刊论文
条目标识符	http://gcip.llas.ac.cn/handle/2XKMVOVA/184888
作者单位	Department of Geological Sciences, University of Idaho, Moscow, ID 83844, United States; Department of Geological Sciences, University of Texas at Austin, Austin, TX 78712, United States; School of Earth Science and Environmental Sustainability, Northern Arizona University, Flagstaff, AZ 86011, United States; Department of Geoscience, University of Wisconsin-Madison, Madison, WI 53706, United States
推荐引用方式 GB/T 7714	Canada A.S.,Cassel E.J.,Stockli D.F.,et al. Accelerating exhumation in the Eocene North American cordilleran hinterland: Implications from detrital zircon (U-Th)/(He-Pb) double dating[J],2020,132(2021-01-02).
APA	Canada A.S.,Cassel E.J.,Stockli D.F.,Smith M.E.,Jicha B.R.,&Singer B.S..(2020).Accelerating exhumation in the Eocene North American cordilleran hinterland: Implications from detrital zircon (U-Th)/(He-Pb) double dating.Bulletin of the Geological Society of America,132(2021-01-02).
MLA	Canada A.S.,et al."Accelerating exhumation in the Eocene North American cordilleran hinterland: Implications from detrital zircon (U-Th)/(He-Pb) double dating".Bulletin of the Geological Society of America 132.2021-01-02(2020).