Browsing by Author "Roquer Rodríguez, Tomás Esteban"

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    Fault-Driven Differential Exhumation in a Transpressional Tectonic Setting: A Combined Microstructural and Thermochronologic Approach From the Liquiñe-Ofqui Fault System, Southern Andes (39°S)
    (2023) Roquer Rodríguez, Tomás Esteban; Arancibia Hernández, Gloria Cecilia; Seymour N.M.; Veloso Espinosa, Eugenio Andrés; Rowland J.; Stockli D.F.; Jons N.; Morata D.
    Crustal deformation in transpressive tectonic settings is partitioned across fault-bounded tectonic blocks whose borders may represent ideal loci for enhanced rock exhumation. Field and petrographic analysis, geothermobarometry, zircon U-Pb geochronology, and zircon and apatite (U-Th)/He thermochronology were applied to intrusive and metamorphic rocks to investigate exhumation patterns of fault blocks delimited by the Liquiñe-Ofqui Fault System (LOFS), Southern Andes (39°S). Our integrated analyses document the relative influences of magmatism, fault-driven differential exhumation, and fault-controlled geothermal flow along the LOFS. Magmatism was concentrated in the Early to Late Jurassic (∼182–151 Ma), Early Cretaceous (∼116–104 Ma), and Miocene (∼17–6 Ma). Dextral mylonitic deformation was most likely coeval with the Miocene pulse of magmatism. Tectonic exhumation occurred across a positive flower structure during the Late Miocene to Early Pleistocene (∼6–2 Ma), and affected kilometric-scale tectonic blocks bound by N-striking, steeply dipping faults of the LOFS. Fault-controlled geothermal flow occurred from the Early Pleistocene to the present-day (∼1.5 Ma-present). Our results suggest that individual faults not only facilitate exhumation of tectonic blocks but also act as pathways for long-term hydrothermal fluid flow.
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    Mineral resource estimation for a placer gold deposit in Cordón Baquedano mining district, Tierra del Fuego, Chile (54°S)
    (2025) Serra Silva, Juan De Dios; Ortiz, Julián M.; Jara, José Joaquín; Marquardt Román, Carlos Jorge; Del Valle Lagos, Felipe Ignacio; Roquer Rodríguez, Tomás Esteban
    The genesis of gold placer deposits is related to different superficial processes, having varied characteristics and complex mechanisms of mineral concentrations. They are often exploited by medium to small-scale miners, with high geological uncertainty and/or without proper geological characterisation. This represents a difficulty for mineral resource estimation, and usually simpler geometric methods are employed. The Cordón Baquedano Gold Mining District (CBGMD) in southernmost South America has been a source of detrital gold for over a century. Some attempts of industrialised mining occurred but without success. Furthermore, the existing metallogenic models are over 30 years old and do not represent the complexity and variety of the deposits found in the district. This research follows the common practices for mineral inventory estimation to create a resource model for the Mina Nueva Deposit (MND) in the CBGMD. Mineralisation and resource models are proposed by using traditional and geostatistical methods. The results of this study indicate that the gold resources in the MND varies from 8,070 to 10,730 ounces using newly acquired dataset, and from 16,720 to 18,280 ounces for a database that incorporates new and historical information. This illustrates the great complexity and variability of results when estimating mineral resources within placer gold deposits in this area.