气候变化领域集成服务门户(CCPortal): Hydrothermal silicification in the intraplate Samambaia seismogenic fault, Brazil: Implications for fault loss of cohesion and healing in rifted crust

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DOI	10.1016/j.tecto.2021.229002
	Hydrothermal silicification in the intraplate Samambaia seismogenic fault, Brazil: Implications for fault loss of cohesion and healing in rifted crust
	Bezerra F.H.; Balsamo F.; Corsi G.; Legrand J.M.; Sousa M.O.L.; Nogueira F.C.C.; Salvioli-Mariani E.; Menezes C.P.
发表日期	2021
ISSN	00401951
卷号	815
英文摘要	This study investigates the Samambaia seismogenic fault at the border of the Potiguar rift Basin, Brazil, to evaluate the relationships among hydrothermal processes, seismicity, and preexisting tectonic fabric. The fault is a 27 km-long structure composed of three left-bend, en echelon segments spaced 1.0–1.5 km apart. The segments strike N31°E – N35°E, dip 70° NW and have focal depths between 1 and 9 km. The seismogenic fault coincides with a swarm of silica-rich veins that range in size from a few centimeters wide and 1–2 m long to 20–50 m wide and hundreds of m long. These structures encompass a V1 vein set composed of quartz veins parallel to the Proterozoic-Archean basement metamorphic foliation and a V2 vein set composed of chalcedony, opal, cryptocrystalline silica, and quartz geodes that cut across Cretaceous siliciclastic and carbonate sedimentary units in the basin and the basement. Fluid inclusions from the V1 vein set yield trapping temperatures of 91 °C–336 °C, whereas the V2 vein set yields temperatures of 147 °C–388 °C. The fluid inclusions and oxygen isotope analyses indicate a magmatic fluid source, although contamination by lateritic soil–derived fluids can be recognized in the V2 vein set. We conclude that in the Samambaia fault, fluid pressure reduces the effective stress until the fault experiences failure, contributing to fault weakening and seismicity. Subsequent cooling of hydrothermal fluids leads to fault healing after coseismic slip and precipitation of Si-rich cements. This process was associated with variation from hydrostatic to lithostatic pressure during cementation, reducing permeability along the fault. Then, the fault locks and fluid pressures begin to rise again. We interpret the superposed V1 and V2 vein sets as the expression of fault-valve behavior caused by repeated fluid-driven reactivation through time along preexisting structures in an extended, rifted crust. © 2021 Elsevier B.V.
关键词	Fluid pressure Hydrothermal fluids Intraplate seismicity Reactivation Seismogenic fault
英文关键词	Mineralogy; Quartz; Hydrothermal fluids; Hydrothermal process; Hydrothermal silicification; Lithostatic pressure; Sedimentary units; Seismogenic faults; Subsequent cooling; Trapping temperature; Buildings
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/207946
作者单位	Departamento de Geologia, Universidade Federal do Rio Grande do Norte, Natal, RN, Brazil; Programa de Pós-graduação em Geodinâmica e Geofísica, Universidade Federal do Rio Grande do Norte, Natal, RN, Brazil; Dipartimento di Scienze Chimiche, della Vita e della Sostenibilità Ambientale, Università di Parma, Italy; Departamento de Engenharia do Petróleo, Universidade Federal de Campina Grande, Campina Grande, PB, Brazil
推荐引用方式 GB/T 7714	Bezerra F.H.,Balsamo F.,Corsi G.,et al. Hydrothermal silicification in the intraplate Samambaia seismogenic fault, Brazil: Implications for fault loss of cohesion and healing in rifted crust[J],2021,815.
APA	Bezerra F.H..,Balsamo F..,Corsi G..,Legrand J.M..,Sousa M.O.L..,...&Menezes C.P..(2021).Hydrothermal silicification in the intraplate Samambaia seismogenic fault, Brazil: Implications for fault loss of cohesion and healing in rifted crust.Tectonophysics,815.
MLA	Bezerra F.H.,et al."Hydrothermal silicification in the intraplate Samambaia seismogenic fault, Brazil: Implications for fault loss of cohesion and healing in rifted crust".Tectonophysics 815(2021).