DOI: 10.1016/j.epsl.2020.116177
论文题名: Geochronologic constraints on deformation and metasomatism along an exhumed mylonitic shear zone using apatite U-Pb, geochemistry, and microtextural analysis
作者: Odlum M.L. ; Stockli D.F.
刊名: Earth and Planetary Science Letters
ISSN: 0012821X
出版年: 2020
卷: 538 语种: 英语
中文关键词: apatite
; geo-thermochronology
; metasomatism
; rift margin
; shear zone evolution
; tectonics
英文关键词: Analytical geochemistry
; Apatite
; Binary alloys
; Deformation
; Dynamic recrystallization
; Exploratory geochemistry
; Lead alloys
; Mineralogy
; Rare earth elements
; Rare earths
; Silicate minerals
; Tectonics
; Trace elements
; Zircon
; Brittle ductile transitions
; Dissolution-reprecipitation
; Light rare earth elements
; metasomatism
; Partial recrystallization
; rift margin
; Shear zone
; Thermochronology
; Uranium alloys
; apatite
; Cretaceous
; deformation
; geochemistry
; geochronology
; metasomatism
; mylonite
; rift zone
; shear zone
; thermochronology
; uranium-lead dating
; Pyrenees
英文摘要: Directly dating and characterizing deformation and metasomatism in fault zones is critical to understanding fault zone processes and lithospheric evolution. Integrated apatite U-Pb geo-thermochronometry, geochemistry, and microtextural analysis has potential to directly date and characterize deformation and fluid-rock interactions in shear zones using a single mineral phase. Integrated apatite U-Pb, microtextural, and trace and rare earth element results from an exhumed mylonitic shear zone, the Main Mylonitic Band in the Northern Pyrenees, constrain timing of deformation and metasomatism along the shear zone as Early Cretaceous, synchronous with ductile deformation and exhumation of middle-lower crustal gneisses in the footwall, and significant mineralization and metasomatism in the brittle hanging wall. Samples from the hanging wall preserve magmatic apatite U-Pb crystallization ages that overlap with zircon and monazite U-Pb ages of ∼300 Ma, granitic geochemical trends, and primary magmatic growth zoning. Footwall samples below the MMB record dynamic recrystallization of apatite associated with mylonitization and exhumation of the gneisses in the Early Cretaceous. Apatite along the MMB record partial recrystallization via dissolution-reprecipitation associated with shearing and circulation of deeply sourced fluids along the shear zone evident by mixed ages (300-100 Ma), geochemical signatures enriched in light rare earth elements, and patchy microtextures. The MMB likely acted as a conduit for deeply sourced fluids that affected the brittle-ductile transition, strain localization, and fluid pathways through the continental crust. This study demonstrates that the integration of apatite U-Pb geo-thermochronology, geochemistry, and microtextural analysis is a powerful approach to dating deformation and metasomatism, characterizing grain scale deformation and (re)crystallization processes, and geochemically characterizing fluid-rock interactions in exhumed middle crustal shear zones. © 2020 Elsevier B.V. Citation statistics:
资源类型: 期刊论文
标识符: http://119.78.100.158/handle/2HF3EXSE/165189
Appears in Collections: 气候变化与战略
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作者单位: Jackson School of Geosciences, University of Texas at Austin, Austin, TX, United States
Recommended Citation:
Odlum M.L.,Stockli D.F.. Geochronologic constraints on deformation and metasomatism along an exhumed mylonitic shear zone using apatite U-Pb, geochemistry, and microtextural analysis[J]. Earth and Planetary Science Letters,2020-01-01,538