Villanes, C., Wiemer, D., and Hagemann, S.G. (2023) 4d Tectonic-Magmatic Evolution and Regional Implications for The Pataz Gold Deposits, Eastern Andean Cordillera, Northern Peru. In: Proceedings of the 26th World Mining Congress. pp. 1474-1485. From: 26th World Mining Congress, 26-29 June 2023, Brisbane, QLD, Australia.

PDF Restricted to Repository staff only

Abstract

The Pataz gold vein system represents one of the major gold deposits in the world-class Paleozoic Pataz-Parcoy gold districts in the northern Eastern Andean Cordillera of Perú. Total gold resources are estimated at over 17 Moz, and have been mined industrially since the late 1980’s. The deposit is hosted by the Carboniferous Pataz batholith, with minor gold lodes in adjacent Neoproterozoic-Early Paleozoic basement rocks. This contribution presents an overview of results from an ongoing multi-scale and -method exploration program aimed at the tectonic-magmatic reconstruction of the Pataz gold deposits and adjacent regions, to identify and develop structural, geochemical and geochronological, target criteria and strategies.

District- to vein-scale structural-kinematic data record a two-stage emplacement of the auriferous vein system. Stage 1 quartz-pyrite veins document an orogenic-style through fault-valve activity within a transpressional regime. Hydraulic breccia veins were superseded by crack-seal veins displaying increasing shear-strain accommodation. Stage 2 quartz-pyrite-galena-sphalerite vein in-fill attests to the re-opening of former veins, coinciding with the formation of normal faults, during a switch towards a transtensional regime. Establishment of the vein system geometry can be explained by three major controlling factors: i) inheritance of structures from the underlying basement, ii) dextral strike-slip along the major Rio Marañon fault, and iii) a tectonic switch from transpression to transtension within an overall ~NE-directed far-field stress field.

On the regional-scale, the Poderosa deposits are situated within a dilational jog, marked by a NNW-to N-trend of the Rio Marañon fault, delineated by intersections with identified cryptic NW-trending faults, sub-parallel to the structural grain of the basement. The cryptic structures control the localization of the vein system, and formed during the ~490-440 Ma Famatinian orogen. The relative timing of successive magmatic intrusions and available geochronological data implies that the tectonic switch and accompanying vein system initiation occurred at ca. 332-330 Ma, directly after solidification of the >350 to 332 Ma Western Suite of the Pataz batholith. Magmatic intrusions associated with the ca. 329-305 Ma Eastern Suite of the batholith lack evidence for vein-style gold. The Carboniferous magmatism shows a compositional bimodality of gabbro/basalt and associated dikes, and a differentiated suite of granodiorite/dacite - granite/rhyolite, across a SiO2 gap (57-62 wt.%). The primitive, mafic end-members are hydrous and oxidized, and are interpreted to represent ore-carrying recharge melts that accumulated in the deep- to mid-crust.

Ongoing work employs air-borne geophysics, and pathfinder elements and zircon-based isotopic analytical techniques. These new data sets are currently tested in the application of mine-scale, brown- and greenfield exploration paired with multi-scale prospectivity analyses.

Item ID:	83685
Item Type:	Conference Item (Research - E1)
ISBN:	9780646875651
Copyright Information:	© 2023 by the 26th World Mining Congress 2023 (WMC 2023), Inc. All rights reserved.
Date Deposited:	21 Jan 2025 01:00
FoR Codes:	37 EARTH SCIENCES > 3705 Geology > 370508 Resource geoscience @ 100%
SEO Codes:	25 MINERAL RESOURCES (EXCL. ENERGY RESOURCES) > 2503 Mineral exploration > 250305 Precious (noble) metal ore exploration @ 100%
Downloads:	Total: 5
	More Statistics