Journal of South American Earth Sciences 82 (2018) 239e260 Contents lists available at ScienceDirect Journal of South American Earth Sciences journal homepage: www.elsevier.com/locate/jsames Mineralogy, structural control and age of the Incachule Sb epithermal veins, the Cerro Aguas Calientes collapse caldera, Central Puna * Natalia Salado Paz a, ,Ivan Petrinovic b, Margarita Do Campo c, Jose Affonso Brod d, Fernando Nieto e, Valmir da Silva Souza f, Klauss Wemmer g, Patricio Payrola a, Roberto Ventura f a Instituto de Bio y Geociencias del NOA (IBIGEO), Universidad Nacional de Salta-CONICET, Av. Bolivia 5150, Salta 4000, Argentina b Centro de Investigaciones en Ciencias de la Tierra (CICTERRA), Universidad Nacional de Cordoba-CONICET, Cordoba X5016GCA, Argentina c Instituto de Geocronología y Geología Isotopica (INGEIS), Universidad Nacional de Buenos Aires- CONICET, Ciudad Universitaria C1428EHA CABA, Argentina d Facultade de Ci^encias e Tecnologia (FC), Universidade Federal de Goias, Brazil e Dpto de Mineralogía y Petrología e I.A.C.T, Universidad de Granada-CSIC, Avda. Fuentenueva s/n, 18002 Granada, Spain f Instituto de Geociencias, Universidade de Brasília, Campus Universitario Darcy Ribeiro, Asa Norte, CEP 70910-900, Brasília, DF, Brazil g University of Goettingen, Geoscience Centre, Goldschmidtstraße 3, 37077 Goettingen, Germany article info abstract Article history: The Incachule Sb epithermal veins is located near to the N-E rim of the Cerro Aguas Calientes collapse Received 28 March 2017 caldera (17.5e10.8 Ma), in the geologic province of Puna, Salta- Argentina. It is hosted in Miocene felsic Received in revised form volcanic rocks with continental arc signature. The district includes twelve vein systems with minerali- 23 June 2017 zation of Sb occurring in hydrothermal breccias and stockwork. The veins are composed of quartz-sulfide Accepted 9 July 2017 with pyrite, stibnite and arsenopyrite. All around the veins, wall rocks are variably altered to clay Available online 26 August 2017 minerals and sulfates in an area of around 2.5 km wide by more than 7 km long. The hydrothermal alterations recognized are: silicic, phyllic and argillic. Keywords: Collapse caldera The veins are characterized by high contents of Sb, As, and Tl and intermediate contents of Pb-Zn-Cu, fl Hydrothermal breccia and traces of Ag and Au. Homogenization and ice-melting temperatures of uid inclusions vary from 34 Epithermal 125 Cto189 C and À2.4 CtoÀ0.8 C. The isotopic data indicated a range of d S À3.04‰ to þ0.72‰ Low sulfidation consistent with a magmatic source for sulfur. We present the firsts K-Ar ages for hydrothermal illite/smectite mixed layers (I/SR1, 60% illite layers) and illite that constrain the age of the ore deposit (8.5e6.7 ± 0.2 Ma). The data shown here, let characterized the Incachule district as a shallow low sulfidation epithermal system hosted in a collapse caldera. Our data also indicate that mineralization is structurally controlled by a fault system related to the 10.3 Ma collapse of Aguas Calientes caldera. The interpreted local stress field is consistent with the regional one. © 2017 Elsevier Ltd. All rights reserved. 1. Introduction 2002; Sillitoe, 2008). This applies particularly to the Central Puna (~24S), which is one of the largest ore districts with silver, lead, In the Puna geological province profuse magmatic activity copper and gold mineralizations in epithermal veins (Sureda et al., occurred during the Miocene, giving place to different kinds of 1986; Pelayes, 1981; Sillitoe, 2008; Zappettini, 1999; Ramallo et al., volcanic and subvolcanic forms comprising stratovolcanoes, cal- 2011). Previous studies were focused on the mineralogy of the ore deras, and domes. Several metallogenetic major episodes, in some deposits, with the goal of defining whether or not they were of the cases of economic interest, are linked with that magmatic activity epithermal type (Arganaraz~ and Sureda, 1979; Morello, 1968). (Coira, 1983; Caffe, 1999; Kay and Mpodozis, 2001; Chernicoff et al., However, those studies did not explore the genetic linkage between the mineralization and specific volcanic episodes and/or volcanic centers. * Corresponding author. In the case of the Incachule mine, located in the Central Puna E-mail address: [email protected] (N. Salado Paz). http://dx.doi.org/10.1016/j.jsames.2017.07.002 0895-9811/© 2017 Elsevier Ltd. All rights reserved. 240 N. Salado Paz et al. / Journal of South American Earth Sciences 82 (2018) 239e260 (Fig. 1), previous works interpreted the mineralization as epi- 2. Regional geological setting thermal, and related it with the activity of the Quevar volcano (JICA, 1993; Zappettini, 1999; Chernicoff et al., 2002). In this study, we The Cerro Aguas Calientes collapse caldera hosts a Sb mineral- present new data suggesting a temporal and spatial link between ization and is located in the geological province of Puna (Turner and the mineralization of the Incachule area and the cerro Aguas Cal- Mendez, 1979), on the trace of the Calama-Olacapato-El Toro ientes collapse caldera and with the local and regional tectonic Lineament, a major strikeeslip fault system oriented NWeSE and framework. oblique to the NeS tectonics trends of the central Andes (Mon, The relationship between epithermal deposits and collapse 1979; Salfity, 1985). The products of the collapse caldera cover an calderas has been cited for various examples globally, where those area of 1700 Km2, with a late stage of resurgence in the caldera landforms are important structural traps for localization and dis- center that uplifts 1000 m the outcrops of the intracaldera with tribution of ore deposits. In the case of the geological province of respect to outflow caldera ignimbrites. The caldera has 15 km in the Puna, hydrothermal activity hosted in collapse caldera were diameter with the major axis oriented N30E in a left-lateral mentioned for northern Puna (Coira, 1999), but the relationship of transpressive setting (Petrinovic et al., 2010). magmatism and structure of the caldera remains as a matter of In Fig. 1 we summarize the geological background of the area. debate. Regarding the Central Puna (~24S), the first references that Thus, the stratigraphic basement of the studied area comprises the links the origin of polymetallic veins with posthumous volcanic Neoproterozoic-Lower Cambrian Puncoviscana Formation (marine activities and collapse caldera correspond to Petrinovic (1999) for low grade metasedimentary sequences, Turner, 1960) and a low the Aguas Calientes and to Riller et al. (2001) for the Negra Muerta Paleozoic plutonic-volcano-sedimentary marine sequence calderas. However, studies aimed to understand the relationship (Omarini et al., 1984; Coira et al., 2001; Viramonte et al., 2007). between magmatic and/or collapse caldera event structures Northward of the study area, Cretaceous-Paleocene continental (doming, subsidence, resurgence) and the hydrothermal- sedimentary sequences of the Salta Group crop out (Turner, 1960). mineralization episodes responsible for the Incachule ore district The Cretaceous Pirgua Subgroup is the best exposed unit of the have not yet been done. Salta Group in the area of the Piedra Caída-Cajon creeks (Vilela, The aim of this study is to characterize the mineral association of 1969). To the north and west of the study area, younger continen- the hydrothermal alteration halos and the mineralized zones, to tal sedimentary sequences, the Pastos Grandes Group occurs constrain the main features of the mineralizing fluids, based on (Turner, 1972). Miocene-Pliocene volcanic rocks of dacitic-andesitic geochemical analyses of fresh and altered rocks and ore minerals, composition, generally showing high potassium contents, crop out as well as on isotopic and fluid inclusions data. We discuss a genetic extensively in the study area. They comprise ignimbrites originated model for the Sb veins mineralization and its relation with the from cerro Aguas Calientes collapse caldera, ignimbrites and lavas caldera collapse and their structure. from central eruptions of Quevar and Tuzgle stratovolcanos and Incachule is the first ore deposit in Central Puna for which the volcanic rocks from minor eruptive centers (Petrinovic et al., 1999), genetic linkage with collapse caldera is investigated, thus the un- such as the domes and subvolcanic bodies of Concordia, El Morro, derstanding of the processes that originate this deposit can be Organullo, and Rupasca (Fig.1), with ages ranging between 12.1 and useful to understand the relationship of mineralized systems with 13.5 Ma obtained on biotite using the K-Ar method (JICA, 1993; caldera events or structure in similar mineral ore deposits in the Petrinovic et al., 1999). The latest records of volcanic activity in Central Andes. the area correspond to the monogenetic basaltic centers of the Negro de Chorrillos and San Jeronimo, which were dated (K/Ar Fig. 1. A- Regional geological map of the study area. Modified from Blasco et al. (1996), Petrinovic et al. (1999), and Petrinovic et al. (2010). N. Salado Paz et al. / Journal of South American Earth Sciences 82 (2018) 239e260 241 whole rock) by Aquater (1980) at 0.2 ± 0.08 Ma and 0.78 ± 0.1 Ma, a laminated structure consisting of 2 cm-long sheets (Fig. 2C). respectively, and the explosive rhyolitic centers in Tocomar with Phyllic alteration affects the Verde Ignimbrite, surrounding the ages between 1.15 and 0.5 Ma (Coira and Paris, 1981; Petrinovic and silicic alteration halos as an elliptical zone (Fig. 3H). The alteration Colombo Pinol,~ 2006). is intense to moderate and pervasive. According to Petrinovic et al. (2010) the evolution of the Aguas Argillic alteration is located in the northwest and south borders Calientes collapse caldera comprises two caldera-forming episodes of the phyllic alteration halo. In the field it can be identified by its that occurred at 17.15 Ma and 10.3 Ma. Both caldera collapses are whitish and yellowish colours. This zone shows intense and quite similar in shape, location and characteristics. The 17.5 Ma pervasive alteration (Fig.