Epithermal precious metal mineralization in a strike-slip corridor; the San Dimas District, Durango, Mexico

Abstract

The San Dimas district, Durango, Mexico, was investigated to define the structural control of epithermal AgAu mineralization and to unravel the tectonic history of the area. Three distinct deformational events have been identified. Deformational event D1 is characterized by the formation of subvertical east-west-to east-northeast-west-southwest-trending tension gashes and hybrid extensional shear fractures that were caused by the ongoing but weakened compression due to subduction west of Mexico during the Early Oligocene. Changing stress conditions during deformational event Ds developed north-south-trending right-lateral strike-slip faults with accompanying secondary structures, forming a complex pattern of a transtensional corridor. The structures of both D1 and D2 are hosted by the Lower Volcanic Group and the underlying Piaxtla intrusive rocks, and they carry low-sulfidation epithermal silver-gold mineralization. Subsequent extension on reactivated north-south-trending strike-slip faults and northwest-southeast-trending normal faults established Basin and Range-type tectonics through both the Oligocene and Miocene. The transition from compression to extension is documented by this strike-slip corridor which was established during the Late Oligocene.

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“…38 and ca. 32 Ma (Horner and Enríquez, 1999). This constrains this fi rst extensional episode as Late Oligocene, as inferred in the Presidio valley.…”

“…Microstructural studies established that the fi rst episode formed a negative fl ower structure defi ned by northsouth-to north-northwest-striking faults with right-lateral extensional kinematics, distributed in a 4-km-wide belt east of Tayoltita (Horner and Enríquez, 1999). This right-lateral transtensional corridor is the northern prolongation of the breakaway fault zone observed in the Presidio River valley (Tayoltita-Pueblo Nuevo fault system).…”

“…2), where some of the faults (e.g., the prominent Ballena and Cabreras faults) are also northwest trending and served as mineralization pathways during the Early Miocene (RamosRosique, 2013). The direction of extension during this fi rst phase is not well constrained but, considering the right-lateral component of motion reported in the northern part of the Tayoltita-Pueblo Nuevo fault system (Horner and Enríquez, 1999), it may be slightly oblique with respect to the main faults, i.e., west-northwesteast-southeast directed (Fig. 15).…”

Internal vein texture and vein evolution of the epithermal Shila-Paula district, southern Peru

“…Nevertheless, most studies devoted to this vein type have concentrated more directly on ore-forming factors such as: (1) the ore and alteration mineralogy, combined with chemical and textural aspects (e.g., Hayba et al 1985;Petersen et al 1990;Dong et al 1995;White and Hedenquist 1995); (2) physico-chemical and isotopic characterization of the involved hydrothermal fluids (e.g., Bodnar et al 1985;De Ronde and Blattner 1988;Moore et al 1992;Matsuhisa and Aoki 1994;Hayashi et al 2001); (3) the effects of boiling, mixing, and water/rock interaction on ore transport and deposition (e.g., Drummond and Ohmoto 1985;Reed and Spycher 1985;Cole and Drummond 1986); and (4) the lateral and vertical zoning of hydrothermal ore and gangue minerals (e.g., Cline et al 1992;Plumlee 1994;Cooke and McPhail 2001;André-Mayer et al 2002). Very few studies were focused on the geometric and textural aspects of mineralized epithermal veins in relation to the regional structural setting (e.g., Fletcher et al 1989;Naito 1993;Horner and Enriquez 1999;Ponce and Glen 2002). Because low-sulfidation deposits occur mainly as veins and/or stockworks, one needs to understand the process of trap formation in which hydrothermal fluids have sufficient space to percolate.…”

Geochronology of Mexican mineral deposits. VI: the Tayoltita low-sulfidation epithermal Ag-Au district, Durango and Sinaloa

“…This tight relationship in time and space between the magmatic and hydrothermal activity that begot these epithermal deposits can be attributed to a genetic link, although associated with the climactic stage of volcanism in the Sierra Madre Occidental (Ferrari et al, 2005(Ferrari et al, , 2007. Additionally, this region experienced important E-W and ENE-WSW strike-slip and normal faulting at the end of the Eocene (Horner and Enriquez, 1999). Therefore, the long-lasting and continuous, albeit episodic, hydrothermal activity that produced the epithermal deposits of Tayoltita is associated with an exceptional (at its time) hypabyssal and volcanic activity whose emplacement was seemingly controlled by a major strikeslip corridor.…”