气候变化领域集成服务门户(CCPortal): Evidence for strain rate variation and an elevated transient geothermal gradient during shear zone evolution in the Cordillera Blanca, Peru

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DOI	10.1016/j.tecto.2020.228610
	Evidence for strain rate variation and an elevated transient geothermal gradient during shear zone evolution in the Cordillera Blanca, Peru
	Hughes C.A.; Jessup M.J.; Shaw C.A.; Newell D.L.
发表日期	2020
ISSN	00401951
卷号	794
英文摘要	The Cordillera Blanca shear zone (CBSZ) occupies the footwall of the Cordillera Blanca detachment fault, an active low-moderate angle detachment fault extending for ~200 km along the western margin of the Cordillera Blanca in central Peru. Recrystallized quartz paleopiezometry, two-feldspar thermometry on asymmetric strain-induced myrmekite, and structural analysis from the CBSZ provide evidence for shear zone evolution within a transient elevated geotherm during syn-convergent extension. Shear zone width varies by a factor of six along strike, with widths of up to ~400 m within the central segment of the shear zone. Microstructurally-derived strain rates, calculated from quartz paleopiezometry and two-feldspar thermometry results, are on the order of 10−14 to 10−12 s−1 and are broadly consistent with macrostructurally-derived strain rates of 10−14 to 10−13 s−1 calculated from shear zone thickness and previously determined exhumation rates. Within the context of existing thermochronological data, constraints on batholith emplacement, and previously determined offset along the Cordillera Blanca detachment, our data suggest that ductile deformation in the CBSZ occurred within a transient elevated geothermal gradient of at least ~50 °C/km and potentially as high as ~100 °C/km, which deviated from a ~30 °C/km gradient for an unspecified duration of time. We discuss the evolution of the Cordillera Blanca, where observed deformation fabrics are related to strain localization along an exhuming fault as well as thermal weakening from the interplay between faulting and magmatism. © 2020 Elsevier B.V.
关键词	Cordillera Blanca Geothermal gradient Paleopiezometry Shear zone Strain rate Strength profile
英文关键词	Deformation; Faulting; Feldspar; Quartz; Thermometers; Detachment fault; Ductile deformations; Exhumation rates; Feldspar thermometries; Geothermal gradients; Rate variation; Strain induced; Strain localizations; Strain rate; deformation; detachment fault; faulting; footwall; geothermal gradient; magmatism; shear zone; strain rate; strength; Ancash; Cordillera Blanca; Cordillera Occidental [Peru]; Peru
语种	英语
来源期刊	Tectonophysics
文献类型	期刊论文
条目标识符	http://gcip.llas.ac.cn/handle/2XKMVOVA/207776
作者单位	Department of Earth and Planetary Sciences, University of Tennessee- Knoxville, 1621 Cumberland Avenue, 602 Strong Hall, Knoxville, TN 37996-1526, United States; Department of Earth Sciences, Montana State University, P.O. Box 173480, Bozeman, MT 59717-3480, United States; Department of Geosciences, Utah State University, 4505 Old Main Hill, Logan, UT 84322, United States
推荐引用方式 GB/T 7714	Hughes C.A.,Jessup M.J.,Shaw C.A.,et al. Evidence for strain rate variation and an elevated transient geothermal gradient during shear zone evolution in the Cordillera Blanca, Peru[J],2020,794.
APA	Hughes C.A.,Jessup M.J.,Shaw C.A.,&Newell D.L..(2020).Evidence for strain rate variation and an elevated transient geothermal gradient during shear zone evolution in the Cordillera Blanca, Peru.Tectonophysics,794.
MLA	Hughes C.A.,et al."Evidence for strain rate variation and an elevated transient geothermal gradient during shear zone evolution in the Cordillera Blanca, Peru".Tectonophysics 794(2020).