DOI: 10.1016/j.tecto.2020.228610
论文题名: Evidence for strain rate variation and an elevated transient geothermal gradient during shear zone evolution in the Cordillera Blanca, Peru
作者: Hughes C.A. ; Jessup M.J. ; Shaw C.A. ; Newell D.L.
刊名: Tectonophysics
ISSN: 00401951
出版年: 2020
卷: 794 语种: 英语
中文关键词: 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
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. Citation statistics:
资源类型: 期刊论文
标识符: http://119.78.100.158/handle/2HF3EXSE/170609
Appears in Collections: 气候变化与战略
There are no files associated with this item.
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
Recommended Citation:
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]. Tectonophysics,2020-01-01,794