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OVERVIEW OF THE GEOLOGIC SETTING AND PORPHYRY Cu-Mo DEPOSITS OF SOUTHERN PERU Xth International Congress of Prospectors and Explorers Lima Peru May 10 - 14, 2017 Richard M. Tosdal*, Adam T. Simmons**, Alan H. Clark*** * PicachoEx LLC, Folly Beach, SC 29439, U.S.A. [email protected] ** AngloAmerican, London, U.K. ***. Queens University, Kingtson, Ontario K7L3N6, Canada INTRODUCTORY COMMENTS Ranging from Cerro Verde-Santa Rosa in the northwest to the giant Toquepala deposit in the southeast, the Paleocene to early Eocene porphyry Cu belt in southern Perú represents one of the world's most poorly appreciated major concentrations of porphyry Cu deposits in the Andes of South America (Fig. 1). They constitute the northern extent of a belt of similar age porphyry Cu deposits that extends from southern Peru into northern Chile (Camus, 2003; Sillitoe and Perelló, 2005), and lies slightly inboard of the older Cretaceous belt, which includes in southern Perú the Zafranal prospect (Fig. 2). Like their late Eocene to Oligocene brethren in northern Chile (Camus, 2003), the southern Peruvian porphyry Cu-Mo deposits are spatially associated with a major trench-linked fault system in the Precordillera physiographic province of the Andean cordillera. As with most Andean porphyry Cu deposits, the southern Peruvian deposits are related to porphyry stocks intruded relatively late in the magmatic cycle. However, unlike the Eocene Chilean porphyries, much fundamental knowledge about the Peruvian porphyry CuMo deposits is not known because of the lack of geologic studies undertaken therein. This guide outlines the geologic framework of southern Peru as well as the general geology of the deposits to be visited during a field trip associated with the International Congress of Prospectors and Explorers (ProExplo). It updates the initial field guide prepared for the 3rd ProExplo conference held in 2003. The field guide is not intended to be a comprehensive discussion of the deposits and their geologic setting. Instead it is constructed from publicly available information or from our observations and unpublished data. The field guide serves to provide a broad overview of the deposits to be visited on this trip and their geologic

setting. An extensive reference list is provided for those interested in further information.

Figure 1. Porphyry copper belts of the central Andes showing the relationship of the Paleocene and Eocene porphyry Cu deposits in southern Peru to similar age deposits in northern Chile and to the younger late Eocene and Oligocene porphyry Cu deposits in northern Chile and southern Peru. Modified from Sillitoe (1988) and Sillitoe and Perelló (2005). The trip begins with the Cerro VerdeSanta Rosa deposits near Arequipa, which is operated by Sociedad Minera Cerro Verde

(subsidiary of Freeport McMoRan). The trip proceeds south to the cluster of three deposits near Moquegua. These deposits include the giant Cuajone and Toquepala mines operated by Southern Peru Copper Corporation, and the Quellaveco prospect being developed by AngloAmerican.

along the coast in southern Perú and in uplifted fault blocks in northern Chile (Fig. 2). They represent the northern extension of the Famatimian arc that is well developed in western Argentina (Ramos, 2008). They furthermore are of similar age to granitoids present in the eastern cordillera farther north and to the east in central and northern Perú where they intruded the Proterozoic Maraňón Complex (Chew et al., 2007, 2016), which is part of the Amazon craton underlying Brazil to the east. In central Perú, these rocks are bordered by remnants of ophiolitic rocks (Tassinari et al., 2011), which represent the suture between an allochthonous crystalline Paracas terrane and the Amazon craton (Ramos, 2011; Chew et al., 2016). Metamorphism of the early Paleozoic sedimentary rocks in the Ordovician accompanied closure of the back-arc basin and essentially the second collision of the parautochthonous Arequipa Massif with the Amazon craton (Ramos, 2011 and references therein). Overlying the early Paleozoic and older rocks are Carboniferous to Permian rocks known in southern Perú (Fig. 2) by various names, but by the marine sedimentary rocks Carboniferous Ambo Formation and riftrelated subaerial volcanic and sedimentary rocks Permian to Triassic Mitu Group in the vicinity of the porphyry Cu prospects. These sedimentary rocks were deposited in basins currently bounded by westerly striking faults that in the field appear to be inverted growth faults. The Mitu Group rocks are considered related to the onset of early Mesozoic Andean arc rifting related to the breakup of Gondwana, with the major axis of extension principally concentrated along the Proterozoic suture zone in the eastern Cordillera of Perú and Bolivia and along the early Paleozoic basins formed between the Arequipa Massif and the Amazon craton (Jaillard et al., 2000; Sempere et al., 2002; Ramos, 2011).

GEOLOGIC FRAMEWORK Basement to the Mesozoic and early Cenozoic Andean arcs A complex Proterozoic and Paleozoic basement underlies the Andean Jurassic to Eocene magmatic arcs and the Paleocene to early Eocene porphyry Cu belt (Fig. 2). The oldest rocks are the Arequipa Massif, a complex Proterozoic terrane containing rocks with ages between 1.8 and 1.0 Ga (Wasteneys et al., 1995; Tosdal, 1996; Wörner et al., 2000; Lowey et al, 2003; Casquet et al., 2010) that underwent high grade metamorphism at least in southern Perú and perhaps into northern Bolivia during the late Mesoproterozoic around 1.0 Ga (Martignole and Martelate, 2003; Casquet et al., 2010). These rocks are currently considered to be an allochthonous terrane derived from Laurentia, having collided with the Amazon craton during the Sunsas / Grenville orogeny (Loewy et al. 2003; Ramos, 2008, 2011). The complex history of these rocks has imparted distinct radiogenic isotopic compositions to rocks that have interacted with them since their emplacement, (Barreiro and Clark, 1984; Boiley et al., 1990; Tosdal, 1996; Loewy et al 2003; Mamani et al., 2008, 2010) which permits their distribution in the subsurface of the Andes to be mapped and defined. Sedimentary basins are considered to have formed in the late Neoproterozoic to early Cambrian and in the late Cambrian and Ordovician. These rocks mainly are present to the east in the area of the modern Altiplano, and represent rift-drift cycles that are best understood in Chile and Argentina within the Punoviscana basin and in the fold-and-thrust belt of Bolivia (Ramos, 2008 and references therein). These basins represent the effect of rifting that detached the main mass of Laurentia from Amazonia, leaving behind the orphan Arequipa Massif, and the southern extension in Chile and Argentina known as the Antofalla craton (Ramos, 2011). Ordovician calcalkaline granitic rocks of the San Nicolás Batholith intruded the metamorphic basement rocks (Mukasa and Henry, 1990; Loewy et al., 2004), and outcrop

Continental-margin rifting in the midMesozoic Rifting of the continental margin along the western margin of Gondwana in the middle Mesozoic marked the onset of the Andean orogen (Coira et al., 1982; Davidson and Mpodozis, 1990; Benavides-Cáceres, 1999; Sempere et al., 2002). Along most of the leading edge of Gondwana, intra-arc and back-arc rifts formed in a suprasubduction zone environment as result of the steep subduction of a cold oceanic plate and the 2

Figure 2. Simplified geologic map of southern Perú showing distribution of porphyry Cu mines and prospects in the region. Modified from 1:1,000,000 scale geology map available from INGEMMET. Note that multiple units have been combined in some of the map units on the figure; internal contacts between those units are preserved on the simplified map.

oceanward retreat of the trench. Significant volumes of mafic, mantle-derived volcanic and plutonic material was erupted and emplaced in the rift basins (Jones, 1981Atherton et al., 1983, 1985), and detritus shed from the rift margins filled the marine basins (Benavides, 1956; Wilson, 1983, 2000). Active rifting and continental-margin basin formation continued into the early Late Cretaceous until the onset of extension and opening of the southern Atlantic Ocean. The Jurassic to Cretaceous intra-arc rift basin along most of Perú is the HuarmeyCanete basin (Benavides-Cáceres, 1999); the basin in southern Perú is not well defined as the margins have been extensively intruded by Jurassic and Cretaceous granitic rocks and also largely covered by Tertiary continental sedimentary rocks (Fig. 2). However, gravity modeling indicates that the rift continues through the region (Jones, 1981). The continental or northeast boundary of the rift basin is diffuse, but broadly corresponds to the Incaic Megafault in central Perú, the Cincha - Luta and Incapucio faults in southern Perú (Fig. 2), and the Domeyko fault system including the West Fissure in Chile. Within the basin, the Mesozoic rocks are largely of marine origin (Benavides-Cáceres, 1999; Jaillard et al., 2000). Paleozoic and Precambrian rocks cropping out along the coast in southern Perú represent the southwestern rift shoulder (Fig. 2). A variety of ore deposits formed during the rifting include volcanic-hosted massive sulfides in central and northern Perú, iron-oxide-coppergold deposits in southern Perú as well as porphyry Cu deposits (Clark et al., 1990a; Injoque et al., 1997; Injoque-Espinoza, 2002; Winter et al., 2004; Sillitoe and Perelló, 2005; Carlotto et al., 2009; Chen et al., 2010). These deposits furthermore are related metallogenically to the similar ones in northern Chile such as Romeral, Punta del Cobre district, and Mantos Blancos (Bookstrom, 1977; Vila et al., 1996; Marschik and Fontbote, 2002). In southern Perú (Fig. 2), a magmatic arc formed along the coast potentially as early as the late Permian, certainly by the Triassic but primarily during the Jurassic in what is now the Cordillera de la Costa (Jenks, 1948; Narváez, 1964; Clark et al., 1990a; Martínez and Cervantes, 2003; Mamani et al., 2010). Boekhout et al. (2012) report Middle Jurassic U-Pb ages (~172 to 166 Ma) for andesitic lava and detrital zircons in volcaniclastic sandstones that have mean U-Pb ages

ranging from ~170 to 162 Ma. The marine supracrustal rocks and associated plutonic complexes were erupted and or intruded through the crystalline basement terrane of the Arequipa Massif and unconformably overlying upper Paleozoic sedimentary rocks. The largely medium-K calcalkaline basaltic to andesitic volcanic rocks, known as the Chocolate Volcanics, are intercalated with volcaniclastic rocks derived therefrom and locally with limestone. The volcanic rocks are overlain and interfinger in their upper parts with shallow marine sedimentary rock sequences that grade upward and laterally into Jurassic rocks of the Socosani Formation and Yura Group which filled a back-arc extensional basin (Sempere et al., 2002). These rocks are common around Arequipa and the Cerro Verde – Santa Rosa porphyry Cu deposits (Fig. 3; Jenks, 1948). A shortlived shortening event in the earliest Late Cretaceous deformed the sedimentary sequence (Vicente et al., 1989; BenavidesCáceres, 1999; Sempere et al., 2002). Whereas the stratigraphy and temporal constraints on the volcanic sequences are generally poorly understood, considerable work has been devoted to the plutonic complexes that formed during the Jurassic and early Cretaceous (Clark et al., 1990a; Mamani et al., 2010; Boekhout et al., 2012; Demouy et al. 2012). The oldest known plutonic rocks are gabbroic to dioritic in composition that crop out around Arequipa and have Early and Middle Jurassic U-Pb ages between ~200 and 180 Ma (Mukasa, 1986; Demouy et al., 2012); these rocks may represent subplutonic complexes broadly associated with the Chocolate Volcanics. A second episode of plutonism with U-Pb ages between ~175 to 152 Ma is more widespread in the Cordillera de la Costa, and was characterized by more felsic compositions ranging from diorite to granodiorite (Clark et al. 1990a; Boekhout et al., 2012; Demouy et al., 2012). The medium-K calcalkaline plutonic complexes are the oldest members of the Toquepala segment of the Coastal Batholith of Perú (Pitcher et al., 1985; Beckinsale et al., 1985). Radiogenic isotopic compositions of the Jurassic volcanic and plutonic rocks indicate varying interaction with the old crystalline basement rocks underlying southern Peru, with magma derived from mafic lithospheric sources (James, 1982; Boiley et al., 1990; Mamani et al., 200, 2010; Boekhout et al., 2012; Demouy et al., 2012).

Figure 3. Simplified geologic map of deposits. Modified from Jenks (1948; Phelps Dodge, 2002). Continental-margin shortening and magmatism leading to porphyry Cu formation Beginning in the earliest Late Cretaceous and coinciding with the opening of the south Atlantic, a fundamental tectonic and magmatic shift characterized the Andes. The arcs shifted northeastward with time. In central Perú, magmatism, recorded largely by the Lima segment of the huge Coastal Batholith (Pitcher et al., 1985), was continuous throughout the Cretaceous and into the early Tertiary (Mukasa, 1986). In contrast, available age constraints indicate a significant gap in magmatism in the Arequipa and Toquepala segments of southern Perú that, based on available data lasted for 50 to 60 million years, with arc magmatism resuming in the earliest Late Cretaceous (~90 Ma) and continuing into the early Eocene (Mukasa, 1986; Beckinsale et al., 1985; Martínez and Cervantes, 2003; Demouy et al., 2012; Simmons, 2013). The eruptive products and the upper crustal batholiths have largely buried or obliterated the in-land margin of the older rift basin and the Cretaceous fold and thrust belt, except to the northwest of

the

Cerro

Verde-Santa

Rosa

porphyry

Cu

Arequipa east of the Cincha – Luta fault (Fig. 2). Volcanism began at ~90 Ma with the onset of poorly dated, on a regional basis, intermediate composition volcanism forming part of the Huracanne formation at the base of the Toquepala Group (Bellido, 1979; Demouy et al., 2012; Simmons, 2013), which is most extensive in the vicinity of Moquegua (Figs. 2 and 4), but has been largely eroded near Arequipa (Figs. 2 and 3). The Toquepala Group in the vicinity of Moquegua is subdivided into a series of formations that generally has more intermediate composition rocks at the base but become more felsic in composition near the top of the volcanic sequence. Ignimbrite dominates the upper Late Cretaceous Toquepala Group. These formations have various names, including the Huaracanne, Inogoya, Parlalque, Matalaque, and Quellaveco formations (Bellido et al., 1979; Martínez and Cervantes, 2003; Cervantes et al., 2005). Near Cuajone (Fig. 4) in excess of 3000m of volcanic and sedimentary rocks composing the upper parts of the Toquepala Group (Fig. 5) were erupted over a 6 million year time frame between 74 and 68 Ma (Martínez and Cervantes, 2003; Simmons, 2013).

Figure 4. Regional geologic map of the Cuajone – Quellaveco – Toquepala porphyry Cu deposits. Modified from Bellido (1979). Coordinates in Peruvian Coordinate System (PSAD56); zone 19S. Large plutons with principally medium-K calcalkaline granodioritic to granitic compositions form the roots of the arc. Near Arequipa where the level of exhumation is deeper (Fig. 3), plutonic rocks forming the Tiabaya, Linga, and Yarabamba units have UPb ages that range from 90 to 62 Ma (Mukasa, 1986; Demouy et al., 2012), essentially spanning the time frame of the volcanic rocks sequences of the Toquepala Group near Moguegua. In the vicinity of Cuajone and Toquepala, U-Pb ages of the plutons are considerably fewer, and where present are largely younger than their host volcanic rocks; U-Pb ages around between 60 and 65 Ma are reported (Simmons, 2013, Simmons et al., 2013) with K-Ar and Ar-Ar ages on the batholithic rocks extending to slightly younger ages (Clark et al., 1990a; Martínez and Cervantes, 2003). Little

mineralized rock is associated with the Late Cretaceous magmatic rocks, although they form a significant host rock at all of the porphyry Cu deposits. Radiogenic isotopic compositions of the Cretaceous volcanic and plutonic rocks indicate varying interaction with the old crystalline basement rocks underlying southern Perú, with magma derived from mafic lithospheric sources (James, 1982; Boiley et al., 1990; Mamani et al., 2008, 2010; Boekhout et al., 2012; Demouy et al., 2012). Near Arequipa however the degree of crustal interaction between the Cretaceous magma and the ancient crystalline basement rocks is considerably less than is recorded in the Jurassic intrusive rocks (Demouy et al., 2012). Inherited cores in zircons as well as xenocrystic zircons from the Late Cretaceous Toquepala Group with Proterozoic and

Figure 5. Simplified stratigraphic column through the Toquepala Group. Section is measured from near Moquegua toward the northeast and lies to the northeast of Cuajone. Simplified from unpublished mapping by A.T. Simmons.

Archean ages demonstrate that ancient crystalline crust also is present at depth in the Moquegua area (Simmons, 2013). Paleocene to early Eocene porphyry intrusions Porphyry Cu-Mo deposits are associated with Paleocene and early Eocene granodiorite and granite porphyry stocks. They constitute the youngest intrusions in region. At Cerro Verde – Santa Rosa, the porphyry intrusions are dated at about 61 Ma (Mukasa, 1986). At Quellaveco, mineralized and hydrothermally altered porphyry intrusions intruded episodically at ~58 Ma, 56 Ma, and 54 Ma (Sillitoe and Mortensen, 2010; Simmons, 2013; Simmons et al., 2013). At Cuajone and Toquepala, porphyry intrusions have ages of ~56 and 54 Ma, but contain 58 Ma xenocrystic zircons, which suggest there was likely 58 Ma intrusions as well (Simmons et al., 2013). Previously published K-Ar and Ar-Ar ages for these deposits extend to younger ages, and record the cooling of the hydrothermal systems (Clark et al., 1990a; Quang et al., 2003). Valdivia et al. (2015) summarized changes trace element variations in the Cretaceous to early Eocene intrusions, and note a change in composition from normal arc-type Sr/Y composition in the older rocks to elevated Sr/Y compositions >20 that indicate hydrous magmas that on a worldwide basis commonly associated with mineralized porphyry Cu systems (Kay and Mpodozis, 2001; Richards and Kerrich, 2007; Richards et al., 2014). Chiaradia (2015) argues that thickening crust is crucial to forming elevated Sr/Y values, a feature that is common elsewhere in the Andes (Kay and Mpodozis, 2003; Bissig and Tosdal, 2009). There is furthermore a change in rare earth element patterns in the southern Peruvian porphyry intrusions to the characteristic spoon shape (Valdivia et al., 2015) that is also associated with mineralized porphyry intrusions (e.g. Hollings et al., 2005). A major trench-parallel fault system consisting of discontinuous and subparallel faults and splays cuts the western part of the present outcrop of the Late Cretaceous and Paleogene arc, and is coincident with the edge of the Jurassic and Early Cretaceous back-arc rift basin (Fig. 2). This fault system is known as the Incapucio Fault in the Toquepala-Cuajone area. The equivalent fault near Arequipa is the Cincha – Luta systems whose trace in the vicinity is largely

obliterated by the northwesterly elongate Late Cretaceous plutonic rocks (Fig. 2). Kinematics of individual faults and the overall system is complex, with normal, strike-slip as well as contractional strains being accommodated at various time since the Mesozoic (Sébrier et al., 1985; Jacay et al., 2002; Semperé et al., 2005; Carlotto et al., 2005, 2009). Nonetheless, post-Eocene deformation related to shortening in southern Peru regional and post-Oligocene counterclockwise rotation has not significantly modified any of the porphyry Cu centers. Post-porphyry Cu Magmatism largely shifted northeastward soon after formation of the porphyry Cu deposits to be established in the Andahuaylas - Yauri region in the Eocene and Oligocene (Noble et al., 1984; Perello et al., 2003; Carlotto et al., 2009). The northward shift is attributed to the flattening of the subduction zone (Sandeman et al., 1995; James and Sacks, 1999). In southern Perú, the Oligocene Tacaza Group is present near the border with Chile (Fig. 2). These rocks represent the westernmost extent of the arc of that age and locally host hydrothermal deposits of which the recently described latest Oligocene to early Miocene (24-22.5 Ma) Chipispaya porphyry Cu deposit (Valdivia et al., 2014) is the most notable (Fig. 2). In southern Perú, continental clastic sedimentary rocks, the Moquegua formation, now referred to as the Moquegua Group (Decou et al., 2011), record the erosion and degradation of the Cretaceous to early Eocene magmatic arc (Fig. 2). The detritus began filling a fore-arc basin lying west of the porphyry Cu deposits by ~50 Ma, and continued intermittently to ~19 Ma (Tosdal 1981; Quang et al., 2003, 2005; Roperch et al., 2006; Decou et al., 2011). Angular unconformities separate units within the Group. The youngest and upper parts of the new Moquegua Group deposited after ~19 Ma represent pediment deposits cut into the lower units of the Moquegua Groups; these pediment surfaces formed as the region was uplifted and the exoeric rivers draining the Cordillera cut across the forearc toward the Pacific Ocean (Tosdal et al., 1981, 1984; Quang et al., 2005; Decou et al., 2011). Deposition of the upper post-19 Ma parts of the Group record the renewed volcanism in the Cordillera and coincided with the oldest record of supergene enrichment in the porphyry Cu deposits (Clark et al., 1990b;

Quang et al., 2005). Parts of the Moquegua Group interfinger and are laterally equivalent to late Oligocene and Miocene marine deposits of the Camaná Group present along the coast (Decou et al., 2011; Alván et al., 2015). Explosive volcanism resumed in the region at about 25 Ma, with a major pulse of explosive volcanic activity between 25 and 19 Ma forming the extensive ignimbrites of the Huaylillas Formation (Tosdal et al., 1981; Quang et al., 2003). Prior to about 19 Ma, ignimbrites are interbedded with the upper Moquegua Group in the forearc basin but in the Precordillera form prominent plateaus burying a regional scale planar erosional landscape, the Altos de Camilaca surface. Post-19 Ma ignimbrite filling valleys cut into the pediment gravels forming the upper units of the Moquegua Group of Decou et al. (2011) and fill valleys cut into the Huaylillas Formation and older rocks in the Precordillera. These rocks are known in southern Perú as the Chuntacala Formation, which was erupted between 14.8 and 13 Ma and the Asana Formation erupted around 10 Ma (Manrique and Plazolles, 1975; Tosdal et al., 1981; Quang et al., 2005). Tosdal et al (1984) argued that the region by the early Miocene was characterized by low-relief topography with an erosional highland in the Precordillera and an aggradational plain formed by the Moquegua Formation that extended to the Pacific Coast. The widespread presence of late Oligocene and early Miocene zircons in the marine sedimentary rocks of the lower parts but not the upper parts of the Camaná Formation is consistent with this topography (Alván et al., 2015). Rapid broad-scale uplift of the southwest flank of the Andes initiated in the early Miocene and coincided with shortening, orogen-scale uplift, 37° counterclockwise rotation, and accentuation of the major oroclinal bend in the Andes (Isacks, 1988; Roperch et al., 2006; Arriagada et al., 2008; Eichelberger and McQuarrie, 2015). Eruption of small-volume ash-flows of the Chuntacala and Asana Formations accompanied uplift in the immediate area of the porphyry Cu deposits whereas pediment formation and deposition of the upper units of the Moguegua Group represent the time-equivalent rocks in the forearc basin. Supergene enrichment of the porphyry Cu deposits began by 38 Ma, contemporaneous with deposition of the Moquegua Group to the southwest and was

largely completed by about 10 Ma, although local evidence for minor supergene activity persisted into the Pliocene (Clark et al., 1990b; Quang et al., 2005; Sillitoe, 2005). By the late Miocene, the climate was hyper-arid, as the mountain range became a sufficiently elevated orographic feature to create a rain shadow on the western flank (Tosdal et al., 1984). The hyper-arid climate that now dominates the southwestern slopes effectively precluded significant additional supergene modification, and only in-situ oxidation and limited supergene weathering of the deposits occurred. THE SOUTHERN PERUVIAN CU BELT Ranging from Zafranal on the northwest to the Chipispaya prospect on the southeast (Fig. 2), the western Cordillera in southern Perú contains a significant number of porphyry Cu-Mo-Au prospects of which three (Cerro Verde-Santa Rosa, Cuajone, and Toquepala) have been in production for decades whereas a fourth (Quellaveco) is currently under construction. Other prospects including Zafranal, La Calara, Chapi, and Chipispaya have been explored with resources announced, whereas exploration on many others prospects has not reached a stage of resource definition. The four operating and soon-to-be operating mines on porphyry Cu deposits are the focus of the field trip and this section briefly outlines their history and general geology. Cerro Verde – Santa Rosa The Cerro Verde – Santa Rosa porphyry Cu deposit near Arequipa was put into production in 1977 by Minero Perú with reserves of 62 million tonnes of 1% Cu in leachable ore and a resource of 1,2oo Mt at 0.6% Cu of sulfide ore. Reserves announced in 2012 by Freeport McMoRan are 3,920 Mt milled ore averaging 0.38% Cu and 0.015%Mo, 108 Mt of crushed leach ore grading 0.46% Cu, and 94Mt of run-of-mine leach ore grading 0.20% Cu (Stegen, 2014). The description of these deposits, the first stop of the field trip, is adapted from LeBel (1985 and references therein), Quang et al. (2005), and from Phelps Dodge Mining Company (2002) and Sociedad Minera Cerro Verde (2007). Geologic framework and mineralization sequence The Cerro Verde – Santa Rosa deposits consist of two separate porphyry systems 2

separated by about 1 km (Figs. 3 and 6). The deposits are associated with granodioritic porphyries emplaced at about 61 Ma. Plagioclase, biotite, and quartz phenocrysts, typical of many Andean porphyries, dominate the phenocrysts in the porphyry stocks. The stocks are arrayed in a northwesterly zone, and a similar elongation is found within the deposits. The Cerro Verde deposit contains hydrothermal breccias, which are localized along the contact between the porphyry stock and the host Late Cretaceous (~68 Ma) Yarabamba granodiorite (Figs. 3 and 6). Alteration assemblages typical of porphyry Cu deposits characterize both deposits (Fig. 6). There is a central deep zone of potassic alteration assemblage (K feldspar – biotite – magnetite – anhydrite – chalcopyrite – bornite with local chlorite) overlain at shallower depths by phyllic (quartz – sericite - pyrite ± chlorite) alteration assemblages and an outer zone of propylitic alteration assemblage (chlorite – epidote – calcite – pyrite ± minor chalcopyrite). There is a notable zone of enrichment in hydrothermal quartz forming greater than 70% of the rock within the phyllic alteration assemblage. The alteration assemblages in Cerro Verde at shallow depth were zoned about the two porphyry stocks with a 1% Cu shell hosted in the country rock lying between the two stocks (Fig. 7); the stocks coalesced at depth (Fig. 6). The location of the high-grade Cu between two porphyry intrusions suggests multiple episodes of intrusion and porphyry Cu mineralization. In contrast in the Santa Rosa deposit, the 0.5% Cu zone forms a subhorizontal tabular cap cutting through the host porphyry (Fig. 6). Chalcopyrite is the dominant copper sulfide, and at Santa Rosa the pyrite to chalcopyrite ratio varies from 0.5 to 3. Accessory galena, sphalerite, molybdenite and tennantite are also present. At Santa Rosa, the molybdenite and tennantite overlap the margins of the 0.5% Cu shell and are concentrated in the wall rocks. Late galena and sphalerite occur with chalcopyrite within the porphyry stock. The sulfides were deposited from boiling magmatic-derived fluids at about 400°C.

up to 300 m thick and extended up to 465 m below the summit of Cerro Verde (~2903 m.a.s.l.). At Santa Rosa, the supergene sulfide enriched zone is thinner, being about 30 to 50 m thick, and only shallowly buried about 50 m below the surface. The great depth of enrichment at Cerro Verde with respect to Santa Rosa likely reflects the much more permeable breccia host to the deposits. An area of supergene enrichment lies between the two porphyry centers (Fig. 6). Quang et al. (2003) demonstrated polyphase supergene enrichment in the two deposits, with the oldest evidence of significant enrichment having occurred by 3638 Ma, followed by a younger event between 24 and 28 Ma. These two physically distinct enrichment events at Cerro Verde were controlled by major erosional surfaces, the La Caldera and Santa Rosa surfaces respectively (Fig. 6), that progressively developed during protracted exhumation in this part of the Andes. Supergene enrichment at Santa Rosa apparently had a simpler history with only a single blanket forming at ~26 Ma; the presence of a single blanket opens the question of whether, or not, an older early Oligocene enrichment event happened at this center and has since been removed by erosion. Supergene enrichment process at these deposits appears to have diminished in intensity with decreasing age, but with minor supergene enrichment and alteration happening within the Miocene (~12 Ma) and late Miocene and Pliocene (4.9 - 6.7 Ma). Oxidation of the deposit and formation of jarosite occurred in the Pleistocene. Cuajone Cuajone was recognized as a potential porphyry Cu deposits in the 1930’s (Lacy, 1991). It was first drilled in 1942. The 157 Mt at 1.27% Cu prospect at that time was not considered economic (Lacy, 1991). Subsequent drilling in 1952 expanded the resource to 417 Mt at 1.05% Cu. Development on the Cuajone property ceased once Toquepala began production (see below). However, under the pressure from the Peruvian government, Cuajone project began to be developed, with the first production being in mid-1976. Concha and Valle (1999) reported reserves of 1,400 Mt at 0.64% Cu and 0.033% Mo at a cut-off of 0.40% Cu. Total resources and reserves in 2006 are reported to be 2,236 Mt at 0.56% Cu (Southern Peru Copper Corporation, 2007).

Supergene modification Post-mineral modification of the two porphyry Cu deposits is significant. Cerro Verde displayed an extensive bronchantitedominated upper oxide copper zone that overlay a zone of sulfide enrichment that was 3

Figure 6. Cross sections of the Cerro Verde – Santa Rosa porphyry Cu deposit showing the distribution of rock types in upper panel and hydrothermal alteration assemblages (center panel0 and supergene zone in lower panel. Modified from Phelps Dodge (2002) and Quang et al. (2003).

Geologic framework Lacy (1958) published the first geologic description of the property (Fig. 7). Since then, there have been only a few subsequent studies of the hypogene geology of the

deposit, and this giant deposit largely remains poorly documented and largely unknown except for brief summaries by Manrique and Plazolles (1975), Satchwell (1983), and Concha and Valle (1999).

Figure 7. Geologic map of the Cuajone porphyry Cu deposit. Coordinates in Peruvian Coordinate System (PSAD56); zone 19S. Modified from Manrique and Plazolles (1975), Concha and Valle (1999), Southern Peru Copper Corporation (2007a) and Simmons et al. (2013). The Toquepala Group including basalt, andesite and quartz porphyry, is present in the Rio Torata, which crosses the northwestern part of the deposit (Fig. 7 and 8). Late Cretaceous diorite (66.7 ± 1.7 Ma; Park in Concha and Valle, 1999) and granodiorite (64-65 Ma in Simmons et al., 2013) intruded the Toquepala Group volcanic rocks. These plutons form part of the Yarabamba batholith (Simmons et al., 2013) that is widespread in the in the region (Fig. 4). Unlike the other two deposits to the south (see below), the batholithic rocks are not a major host to ore. Most of the ore is hosted in the temporally related porphyry stocks and immediate volcanic wall rocks (Manrique and Plazolles, 1975). At least four intermediate composition porphyry stocks intruded the Toquepala

Group rhyolitic and andesitic host rocks (Figs. 7 and 8). The porphyries are spatially and temporally related to the porphyry Cu deposit (Manrique and Plazolles, 1975). The oldest, mapped in the mine as intrusive andesite (Fig. 7) is pervasively altered to a potassic assemblage of biotite ± K feldspar that is largely barren. An extensively altered and mineralized early quartz-phyric porphyry, mapped as LP1 porphyry, intruded the intrusive andesite unit, and is temporally associated with the bulk of the Cu-sulfide deposition (Concha and Valle, 1999). It lies beneath the Quebrada Chuntacala (Fig. 7), which bisects the main part of the deposit. A second but less altered quartz phyric porphyry, mapped as BLP porphyry, forms an inter- to late mineral intrusive suite. It underlies unconformably post-mineral

Figure 8. Cross sections of the Cuajone mine showing the distribution of rock units, hydrothermal alteration assemblages, and supergene enrichment, oxide Cu and leached-oxide zone. Modified from Clark et al. (1990b) and Southern Peru Copper Corporation (2007a).

ignimbrites and sedimentary rocks in the interfluve between Quebrada Chuntacala and Rio Torata (Fig. 7). Marginal breccias to the inter- to late mineral BLP porphyry are variably mineralized due to the presence of clasts of older well-mineralized porphyry; the breccias are intimately associated with the margins of these stocks (Concha and Valle, 1999). Highly altered andesite dikes within the deposit, which are volumetrically minor, clearly must represent small early to intermineral intrusions related to the larger porphyry units. Simmons et al. (2013) report essentially identical U-Pb ages 55.6 ±0.6 and 56.2 ±0.7 Ma for these three intrusive units that are intimately associated with Cu deposition in the porphyry deposit. Collectively the U-Pb ages indicate intrusion, hydrothermal alteration, and Cu precipitation over a short duration of time, as it becoming evident in most porphyry Cu deposits on a global basis. The youngest porphyry intrusions, mapped as LP3 porphyry (Fig. 7), cut the northern part of the porphyry ore body and outcrop on the margins of the Rio Torata. These weakly altered rocks are latest mineral to post-mineral (Concha and Valle, 1999), and were emplaced almost 2 million years after the main Cu event at 53.5 ± 0.4 Ma (Simmons et al., 2013). Clark et al. (1990a) report an Eocene age of 52.4±1.9 Ma for sericite from a quartz-chalcopyrite-pyrite veined rock in the Rio Torata, which records the finally cooling of the hydrothermal system. Late Oligocene and Miocene sedimentary and volcanic rocks unconformably overlie the Eocene igneous rocks. The oldest rocks form the Huaylillas Formation. The basal ignimbrites of the formation filled a paleovalley to the southeast of the deposit at about 22.8 ± 0.8 Ma (Tosdal et al., 1981; Quang et al., 2005). The top of the formation consists of regionally extensive ignimbrites that form the planar benches on either side of the Cuajone deposit. These ignimbrites were erupted about 19 Ma, and buried the highest of the supergene enriched zones and leached and oxidized rocks that overlay it. Subsequently, a valley was cut down across the northwest trending axis of the deposit, and filled with a sequence of ignimbrites and sedimentary rocks known as the Chuntacala Formation (Manrique and Plazolles, 1975; Tosdal et al., 1981; Satchwell, 1983). These rocks were deposited across leached and oxidized rocks as well as secondary enriched rocks (Clark et al., 1990b). The paleovalley began to fill at

about between 14.8 and 14.2 Ma (Quang et al., 2005), and effectively prohibited further enrichment of the deposit. Mineralization sequence Hydrothermal alteration assemblages at Cuajone are typical for most porphyry Cu deposits. An early biotite ± K feldspar preserved in the intrusive andesite represents the oldest hydrothermal event mapped in the mine (Manrique and Plazolles, 1975; Concha and Valle, 1999). Phyllic alteration assemblages (Fig. 8) of quartz – sericite dominate the porphyry units in the upper levels of the deposits (Concha and Valle, 1999). Quartz veins contain chalcopyrite – pyrite ± bornite and minor enargite. The oldest veins carry bornite and the younger are more pyritic. The assemblage of bornite – pyrite ± enargite seen in some veins at high levels suggest local transition to high sulfidation type assemblages commonly found in porphyry Cu deposits where pervasive sericitic alteration has destroyed the buffering capacity of the host rocks. A transitional assemblage of sericite - chlorite lies between the pervasively biotite altered rocks and the phyllic alteration assemblages and between the phyllic and propyllitic alteration assemblages. Typical potassic alteration assemblages of biotite – magnetite – quartz – K feldspar – anhydrite – Cu-Fe sulfide lie at depth. Late molybdenite - quartz veins cut the Cu-bearing veins. Within areas of less intense hydrothermal alteration, late stage mixed argillic – phyllic assemblages (intermediate argillic assemblage) composed of smectite clays – chlorite – sericite (illite) overprint the higher temperature assemblages but did not remove Cu (Satchwell, 1983). Clearly the evidence for two intrusive events each carrying an associated hydrothermal fluid has complicated the simple hydrothermal picture of the deposit. Manrique and Plazolles (1975) note that the distribution of sulfides and Cu grade is very regular both laterally and vertically, except where the younger and less mineralized intrusions diluted the Cu ore grade. Pyrite, chalcopyrite, bornite, molybdenite and lesser amounts of sphalerite, galena, and enargite constitute the hypogene sulfide mineral assemblage. Molybdenite is present in quartz veins or is disseminated in the rock (Concha and Valle, 1999).

Supergene modification The secondary enrichment blanket at Cuajone was only about 20 m thick, the thinnest of all the deposits (Fig. 8). It appears to be a single blanket-like horizon that dipped gently to the west. Immediately above the sulfide-bearing enriched zone was a 40-m thick oxide Cu zone overlies the secondary sulfides, derived from the weathering of secondary Cu sulfides (Clark et al., 1990b). On the southern side of the deposit, the enriched zone tapers to a wedge about 150 m below the unconformity at the base of the 22.8 Ma ignimbrite that forms the lower Huaylillas Formation. A distinct hematitic horizon beneath the unconformity suggests the past presence of supergene sulfides that have now been leached and transported to lower elevations. Tosdal et al. (1984) concluded that this unconformity represented an early stage of the formation of the early Miocene Altos de Camilaca surface, a regionally extensive pediplane that influenced supergene enrichment in each of the deposits. On the northwest side of the deposit, the 14.8 Ma Chuntacala Formation unconformably overlies the secondary sulfide and oxide Cu zones (Fig. 8), effectively dating the end of supergene enrichment. Sillitoe (2005 on figure 18) reported an age for supergene enrichment at Cuajone to pre-date the Huaylillas Formation, and to be contemporaneous with deposition of the upper Moquegua Formation. Clark et al (1990b) concluded that supergene enrichment clearly began prior to the Oligocene, and was probably largely complete by about 22.8 Ma with the final formation of the Altos de Camilaca surface. Further enrichment likely occurred during the down cutting of the valley that was subsequently filled by the Chuntacala Formation, however, this was likely minimal (Clark et al., 1990b). The limited enrichment at Cuajone in comparison with Quellaveco and Toquepala derives directly from the fact that the deposit was largely covered by ignimbrites, which disrupted the paleohydrology, thereby limiting the efficacy of the supergene enrichment process.

1970 before being nationalized and explored further by Minero Perú in 1972 (Candiotti de los Rios, 1995). Announced reserves at that time were 405 Mt at 0.8% Cu (Estrada, 1975). Subsequent exploration by Anglo American Exploration Perú S.A has defined a geological resource of 1,670 Mt at 0.56 % Cu (cut-off at 0.3 % Cu) with reserves of 979 Mt at 0.63 % Cu, 0.021 % Mo and 2.19 g/t Ag, including 213 Mt @ 0.95 % Cu. The details of the deposit are summarized from Estrada (1975), Toropoca (1979), Guerrero and Candiotti (1979), Kihien (1975, 1995), Candiotti de los Rios (1995), Sillitoe and Mortensen, (2010) and Simmons (2013). Geologic framework The Quellaveco deposit is bisected by the Rio Asana, and hypogene and supergene sulfides outcrop on the floor and flanks of the modern river valley (Figs. 9 and 10). The deposit is hosted by a sequence of andesite overlain by the felsic ignimbrites of the Toquepala Group that were intruded by a large ~60 Ma granodiorite batholith. The calcalkaline volcanic rocks of the Toquepala Group include two members (Kihien, 1995). Quartzfeldspar phyric rhyolites of the Quellaveco Rhyolite form the base of the sequence. Andesite and basaltic-andesite flows and breccias of the Samanape Andesite discordantly overlie the older volcanic rocks. Tonalite, granodiorite, and quartz monzonite intrude the volcanic rocks. A series of porphyritic granodiorite stocks intrude the volcanic and plutonic rocks. These rocks are most closely associated in time and space with the porphyry Cu deposit. Late quartz latite dikes cut the complex. Available chronologic data suggest three distinct ages of porphyry intrusion (Sillitoe and Mortensen, 2010; Simmons, 2013). The oldest but volumetrically smallest porphyry unit containing with highest Cu grade was emplaced at ~58 Ma. The volumetrically most abundant and mineralized porphyry units carry most of the contained Cu were emplaced between 56 and 57 Ma. A weakly mineralized set of porphyry intrusions was emplaced at ~54 Ma. On the north bank of the Rio Asana, the deposit is unconformably overlain by unwelded ignimbrites of the Miocene (ca. 13 Ma) Chuntacala Formation (Tosdal et al., 1981) and 10-Ma tuff forming the Rio Asana Formation (Figs. 9 and 10). These rocks filled a paleovalley that paralleled the current Rio Asana on the north. On the south bank, the

Quellaveco Quellaveco was recognized as potential porphyry Cu deposits in the 1930’s (Lacy, 1991). It was explored by Northern Peru Mining and Smelting Co. between 1947 and 1952, Southern Peru Copper Corporation in 2

Figure 9. Geologic map of the Quellaveco porphyry Cu deposit. Coordinates in Peruvian Coordinate System (PSAD56); zone 19S. Modified from Simmons (2013). oldest members (~13 Ma) of the Chuntacala Formation are preserved in small depressions Mineralization sequence. in the exhumed early Miocene Altos de Porphyry Cu-style veins and alteration is Camilaca surface at elevations of about 4000 elongated northwest to southeast (Figs. 9 and m. Ignimbrites of the Chuntacala Formation 11). The hypogene alteration at Quellaveco throughout the Precordillera fill paleovalleys is complex, as the rocks have been exposed cut into the regional Altos de Camilaca to several generations of hydrothermal fluids. surface and overlying Huaylillas Formation. Thus, distinguishing the timing of the wall rock The ash flows of the Chuntacala Formation alteration relative to the rock types and their preserved the secondary sulfide horizon that related vein paragenesis is exceptionally developed during the Miocene. difficult. Nonetheless patterns of alteration

Seven main hypogene alteration mineral assemblages are identified: a) biotite - KFeldspar; b) chlorite over biotite – K feldspar; c) chlorite over biotite - K-feldspar with overprinted quartz-sericite; d) biotite – K feldspar with overprinted quartz - sericite; e) epidote - chlorite; f) epidote - chlorite with overprinted quartz - sericite; and d) quartz sericite (Fig. 11). Felsic mineral sites are altered to hydrothermal K feldspar, quartz sericite and minor epidote, whereas the mafic silicate sites are commonly altered to biotite, chlorite, epidote and in cases of extreme

intense alteration quartz – sericite. The majority of alteration assemblages dominated by K-feldspar and biotite are located within and around early porphyry units and adjacent into the older regional granodiorite. This alteration assemblage typically does not extend far into the host granodiorite with a minimum penetration of approximately 300m from the nearest early porphyry intrusion. Minor K-feldspar - biotite assemblages are spatially associated with some of the intermineral dike complexes.

Figure 10. Cross sections of the Quellaveco deposit showing the distribution of rocks and supergene enrichment, oxide Cu and leached-oxide zone Modified from Clark et al. (1990b) and Simmons (2013).

2

Figure 11. Geologic map of hydrothermal mineral assemblages at Quellaveco. Geologic contacts from figure 9 are shown in dashed lines. Coordinates in Peruvian Coordinate System (PSAD56); zone 19S. Modified from Simmons (2013). Chlorite or quartz - sericite overprinted Kfeldspar - biotite mineral assemblages are mainly restricted to the periphery of the early porphyry units where these rocks intruded the granodiorite unit. Quartz and sericite dominated hypogene alteration assemblages are mainly restricted to the area around the intermineral dike complex at shallow levels in the deposit, and can be mapped on the valley walls at higher elevations above the current

deposit. Epidote and chlorite dominated mineral assemblages are, for the most part, restricted to the granodiorite within the lateral extents of the deposit and to the late porphyry units that intruded older porphyry units. Fluid inclusion thermometry indicates the K-silicate alteration and Cu-Mo sulfides were deposited from high-temperature saline, magmaticderive hydrothermal fluids (Kihien, 1975, 1995). Fluids responsible for some of the

quartz-sericite alteration were of intermediate temperature (>300°C). Some general points can be inferred from the hypogene alteration distribution. Firstly, Kfeldspar and biotite mineral assemblages are in general temporally associated with older porphyry phases (i.e. Early and Earliest Porphyries) and dominate at depth within the system. Quartz-sericite dominated assemblages are temporally associated with intermineral porphyry units and dominate the upper levels within the overall system; presumably these assemblages are underlain at depth by potassic mineral assemblages. Epidote and chlorite dominated mineral assemblages are spatially associated with the distal parts of the Quellaveco resource and temporally associated with the very youngest porphyry units.

Toquepala Toquepala was recognized in the 1930’s as a porphyry Cu prospect by Carl Schmedeman (Lacy, 1991) based upon the surface outcrops of leached and limonite filled veinlets that locally contained copper oxides and carbonate minerals. The Cerro de Pasco company drilled the property through 1942 and outlined a resource of 9 Mt of 4.21% Cu at a cut-off grade of 3%. In 1949, the information and property became part of Northern Peru Mining and Smelting Co. and an exploration program outlined a 363 Mt at 1.05% Cu ore body. Mattos and Valle (1999) report reserves of 300 Mt at 0.83% Cu and 0.07% Mo in sulfide ore and 700 Mt at 0.2 Cu in leachable ore. The current reserve figures do not take into account past production reported to be 558 Mt of 1.03% Cu (Mattos and Valle, 1999).

Supergene alteration An irregular secondary enrichment zone about 50 to 60 m thick developed on the hypogene sulfide ore body (Estrada, 1975; Clark et al., 1990b). It consists of two zones: an upper zone of moderate to strong enrichment overlying a lower Cu grade zone that presumably represents a downward transition into the hypogene ore (Fig. 10). On the north slopes of the Rio Asana (Fig. 10), a 10.1 ± 0.3 Ma ignimbrite of the Rio Asana Formation, and a 13.0 ± 0.4 Ma ignimbrite of the Chuntacala Formation and an underlying conglomerate, which locally contains exotic oxide Cu, unconformably overlie leached and oxidized rocks and subjacent secondary enriched zone (Clark et al., 1990b; Quang et al., 2005). The relationships indicate that the last stage of secondary enrichment occurred in the Miocene. Based on the complex geometry of the secondary enrichment zone and the reconstructed paleogeomorphology (Tosdal et al., 1984; Quang et al. 2003), the enrichment blanket is thought to be the product of two or more superposed enrichment phases (Clark et al., 1990b). The presence of perched horizons of chalcocite and hematitic rich leached zones provide support for the polyphase enrichment history. The enrichment occurred at least in Miocene during the down cutting of broad valleys into the deposit but likely began prior to the final formation of the Altos de Camilaca surface. Supergene ages reported in Sillitoe (2005 on figure 18) indicate enrichment in the early Miocene but also local supergene activity contemporaneous with the Pliocene and younger Barroso Group.

Geologic framework Richard and Courtright (1958) first described the geology of the deposit (Fig. 11). Subsequent study of the deposit has been sporadic, and includes description of Zweng and Clark (1995; see also Clark et al., 1990a), Mattos and Valle (1999), and Southern Peru Copper Corporation (2007b). The porphyry Cu-Mo deposit is associated with a complex intrusive center dominated by several dacite stocks, a dacitic diatreme complex, and extensive hydrothermal breccias. These rocks were emplaced into Paleocene quartz monzodiorite pluton (U-Pb age of 61.4 Ma; Simmons et al., 2013; 40Ar-39Ar age of about 55.5 Ma; Clark et al., 1990; Laughlin et al., 1968) and still older rhyolitic and intermediate volcanic rocks. The volcanic rocks are known as the Serie Alta, Toquepala Series, and Quellaveco quartz porphyry, which are subdivisions of the Quellaveco Formation of the Toquepala Group (Richard and Courtright, 1958; Bellido, 1979). The deposit lies about 1 to 2 km northeast of the Micalaco Fault, which is a subsidiary strand of the Incapucio Fault system that lies still farther to the southwest. The deposit consists of a sequence of alteration and mineralization events that are spatially and genetically related to the multiphase dacitic intrusions. Southern Peru Copper Corporation (2007b) refers to these as dacite porphyry with an U-Pb age of 56.8 ± 0.6 Ma and dacite agglomerate with an U-Pb age of 56.2 ± 0.8 Ma (Simmons et al., 2013). Complex hydrothermal events occurred between the two intrusions, with extensive 2

Figure 12. Geologic map of the Toquepala Mine. Coordinates in Peruvian Coordinate System (PSAD56); zone 19S. Modified from Richard and Courtright (1958), Zweng and Clark (1995) and Simmons et al., (2013). brecciation and chalcopyrite and molybdenite introduction. A large pebble breccia followed intrusion of the dacite agglomerate unit. The early Cu-rich veinlets are most abundant in the oldest porphyry, but these veins cut all the porphyry intrusions. The dacite porphyry unit is the largest intrusion and dominates the pit. Barren tourmaline breccia cuts the porphyry stocks and early Cu-rich veins. Tourmaline breccias are common also in the hills surrounding the open pit, and are a widespread phenomenon in the deposit area. Some quartz – sericite - pyrite alteration accompanied breccia formation, but little

copper was deposited at this time. Late dacite porphyry dikes intrude the tourmaline breccia within the pit (Zweng and Clark, 1995). Late to post-mineral latite porphyry (U-Pb age of 54.3 ± 0.6 Ma; Simmons et al., 2013) intruded all older igneous and hydrothermal units at. The effect of the late activity is to dilute the Cu endowment of the deposit (Zweng and Clark, 1995). Mineralization sequence Early Cu-rich veins accompanied widespread potassic alteration of the

porphyries, with the intensity of alteration decreasing with age, as is common in porphyry Cu deposits (Gustafson and Hunt, 1975; Zweng and Clark, 1995). The veins contain biotite, K- and Na-feldspar as well as chalcopyrite - bornite or are barren quartz with accessory anhydrite. They were deposited from high temperature >400°C fluids with at least 35% wt. percent NaCl equivalent (Zweng and Clark, 1995). The veins are furthermore well developed deep in the deposit at elevations below approximately 2,550 m.a.s.l. Their sinuous character makes them analogous to the early “A-veins” at El Salvador (Gustafson and Hunt, 1975). Zweng and Clark (1975) suggest that only a limited amount of Cu in the Toquepala system was deposited in association with the early veins. Tourmaline veins and breccias cross cut the early Cu-rich veins. These veins and breccias lack appreciable sulfide, and were accompanied by quartz - sericite and tourmaline - quartz alteration of the wall rock. Fluid temperatures are interpreted to have been lower, and about 390°C and only saturated in NaCl (Zweng and Clark, 1995). The net result of this stage of alteration is a large upward-flaring tourmaline breccia that localizes the vertical axis of the Toquepala deposit. Zweng and Clark (1995) suggest that the tourmaline breccia stage at Toquepala may correlate, on a much grander scale, with similar veins that make up the transitional stage at El Salvador (Gustafson and Hunt, 1975). The root of the pipe is suggested to be at an elevation of about 2000 m.a.s.l. above the apex of a deeper porphyry (Zweng and Clark, 1995). Emplacement of the central tourmaline breccia furthermore provided a vertical permeability framework to the deposit that enhanced the upward rise and sulfide deposition during the main stage. Main stage alteration and mineralization consist of chalcopyrite - molybdenite veins responsible for the vast bulk of the metal endowment at Toquepala. Quartzmolybdenite-chalcopyrite and chalcopyritepyrite are the dominant veins. Molybdenite is also present as the matrix to irregular vertically oriented breccia and as a coating on fracture. Sparse magnetite veins deep in the system post-date molybdenite deposition. Zweng and Clark (1995) suggest an upward enrichment of copper relative to molybdenum deposited during this stage. This enrichment is reflected in the abundance of quartz – molybdenite - chalcopyrite veins in the deeper portion of the deposit and their diminished

presence and the dominance of chalcopyrite pyrite in the shallow portions of the deposit. Main stage sulfides were deposited from fluids with an average temperature of about 335°to 360° C and about 35 wt. % equivalent NaCl. Late-stage alteration consisting of quartz – sericite - pyrite veins and texturally destructive albite - sericite, quartz – sericite - pyrite ± andalusite alteration selvages is similar to that found in most porphyry Cu deposits. Highsulfur and arsenic-rich minerals (bornite and tennantite-pyrite) and throughgoing vein fabrics are characteristic. Fluids associated with this stage are of lower temperature, being about 300° C, and salinity in the range of 7 to 8 wt. % NaCl. A 300 m in diameter and >500 m in depth pebble breccia and numerous pebble dikes represent one of the latest events in the deposit. For the most part, these are postmineral and dilute the overall Cu grades. Chalcopyrite has been seen in the matrix of at least 1 pebble dike, thereby implying that pebble dikes probably developed at episodic times over the course of the deposit formation. Supergene enrichment Toquepala had the thickest and most extensive record of supergene enrichment of the three southern porphyry Cu deposits (Richard and Courtright, 1958), but virtually all of the zones have been removed by mining. The oldest record of supergene sulfide enrichment was preserved between 3525 and 3100 m.a.s.l., and lay within 40 to 75 m below a regional early Miocene erosional surface, the Altos de Camilaca surface (Tosdal et al., 1985; Clark et al., 1990b). A supergene age in Sillitoe (2005 on figure 18) is consistent with this interpretation. The most extensive zone had a broadly planar but very irregular upper surface that slopes gently from north to south across the hypogene sulfide deposit between elevations of 3,350 and 3,250 m.a.s.l. The zone had deep roots that were in excess of 150 m deep. Clark et al. (1990b) concluded that the extensive and thick enrichment zone formed in the Miocene after 19 Ma and before 11 Ma. Formation of the enriched zone accompanied uplift of the western slope of the Cordillera. Richard and Courtright (1958) and Anderson (1982) reached a similar conclusion. REFERENCES 2

Alván, A., von Eynatten, H., Dunkl, I., and Gerdes, A. 2015, Zircon U-Pb geochronology and heavy mineral compositions of the Camaná Formation, southern Peru: Constraints on sediment provenance and uplift of the Coastal and Western Cordilleras: Journal of South American Earth Sciences, v. 61, p. 14-32. Anderson, J.A., 1982, Characteristics of leached capping and techniques of appraisal, in Titley, S.R., ed, Advances in the geology of porphyry copper deposits, southwest North America: Tucson, Univ. Arizona Press, p. 245-287. Arriagada, C., Roperch, P., Mpodozis, C., and Cobbold, P.R., 2008, Paleogene building of the Bolivian Orocline; tectonic restoration of the central Andes in 2-D map view: Tectonics, v. 27, TC6014, doi:10.1029/2008TC002269. Atherton, M., Pitcher, W., and Warden, V., 1983, The Mesozoic marginal basin of central Peru: Nature, v. 305, p. 303-305. Atherton, M., Warden, V., and Sanderson, L.M., 1985, The Mesozoic marginal basin of central Peru: a geochemical study of within plate-edge volcanism, in Pitcher, W.S. et al., eds., Magmatism at a plate edge: The Peruvian Andes: Glasgow, Blackie, John Wiley and Sons, p. 47-58. Barreiro, B.A and Clark, A.H., 1984, Lead isotopic evidence for evolutionary changes in magma-crust interaction, Central Andes, southern Perú: Earth Planet. Sci. Let., 69: 30-42. Beckinsale, R.D., Sanchez-Fernandez, A.W., Brook, M., Cobbing, E.J., Taylor, W.P., and Moore, N.D., 1985. Rb-Sr whole-rock isochron and K-Ar age determinations for the Coastal Batholith of Peru, in Pitcher, W.S., Atherton, M.P., Cobbing, E.J., and Beckinsale, R.D., eds., Magmatism at a plate edge: The Peruvian Andes: Glasgow, Blackie, John Wiley and Sons, p. 177-202. Benavides, V., 1956, Cretaceous system in northern Peru: Bulletin American Museum of Natural History, v. 108, p. 252-494. Benavides-Cáceres, V., 1999, Orogenic evolution of the Peruvian Andes: The Andea cycle, in Skinner, B.J., ed., Geology and Ore Deposits of the Central Andes: Society of Economic Geologists Special Publication no. 7, p. 61-107. Bellido, E., 1979, Geologia del cuadrángulo de Moquegua (hoja: 35-u): Lima, Peru, Instituto Geologica Minero Metalalugica, 78 p.

Bissig, T., and Tosdal, R.M., 2009, Metallogeny of carbonate-rock hosted ore deposits in the eastern Cordillera Occidental of Central Perú: a petrochemical study: Journal of Geology, v. 117, p. 499-518. Boiley, M., Ludden, J.N., and Brooks, C., 1990. Geochemical constraints on the magmatic evolution of the pre- and postOligocene volcanic suites of southern Perú: implications for the tectonic evolution of the Central Volcanic Zone: Geological Society of America Bulletin, v. 102, p. 1565-1579. Boekhout, F., Spikings, R., Sempere, T., Chiaradia, M., Ulianov, A., and Schaltegger, U., 2012, Mesozoic arc magmatism along the southern Peruvian margin during Gondwana breakup and dispersal: Lithos, v. 146-147, p. 48-64. Bookstrom, A.A., 1977, The magnetite deposits of El Romeral, Chile: Economic Geology, v. 72, p. 1101-1130. Camus, F., 2003, Geología de los sistemas porfíricos en los Andes de Chile: Servicio Nacional de Geologia y Minería, 267 p. Candiotti de los Ríos, H., 1995. Geología y analisis de datos cuantitativos del yacimento de pórfido de cobre Quellaveco: Sociedad Geologica del Perú, volumen Jubilar Alberto Benavides, p. 33-46. Carlotto, V., Cerpa, L., Cárdenas, J., Quispe, J., and Carlier, G., 2005, Paleogeographic, structural and magmatic evidence for the existence of different lithospheric blocks in the central Andes of soutehrn Peru and northern Chile: 6th International Symposium on Andean Geodynamics (ISAG 2005, Barcelona), Extended Abstracts, p. 146-149. Carlotto, V., and 12 others, 2009, Dominios geotectónicos y metalogénesis del Peru: Boletin de la Sociedad del Peru: v. 103, p. 1-89. Casquet, C., Fanning, C.M., Galindo, C., Pankurst, R.J., Rapela, C.W.,, and Torres, P., 2010, The Arequipa Massif of Peru: New SHRIMP and isotope constraints on a Paleoproterozoic inlier in the Grenvillian orogen: Journal of South American Earth Sciences, v. 29, p. 128-142. Cervantes, J., Martínez, W., Romero, D., Zapata, A., and Navarro, P, 2005, The Matalaque Formation of southern Peru: New stratigraphic and geochemical data: 6th International Sumposium on Andean 3

Geodynamics (ISAG 2005, Barcelona), Extended Abstracts, p. 162-165. Chen, H.Y., Clark, A.H., Kyser, T.K., Ullrich, T.D., Baxter, R., Chen, Y.M., Moody, T.C., 2010, Evolution of the giant Marcona-Mina Justa iron oxide copper gold district, south-central Peru: Economic Geology, v. 105, p. 155-185. Chew, D., U. Schaltegger, J. Kosler, M. J. Whitehouse, M. Gutjahr, R. A. Spikings, and A. Miskovíc (2007), UPb geochronologic evidence for the evolution of the Gondwanan margin of the northcentral Andes, Geol. Soc. Am. Bull., 119, 697–711, doi:10.1130/B26080.1. Chew, D., Pedemonte, G., and Corbett, E., 2016, Proto-Andean evolution of the Eastern Cordillera of Peru: Gondwana Research, v. 35, p. 59-78. Chiaradia M., 2015 Crustal thickness control on Sr/Y signatures of recent arc magmas. an Earth scale perspective. Science Report, v. 5, 8115, DOI. 10.1038/srep08115. Clark, A.H., and 10 others, 1990a, Geologic and geochronologic constraints on the metallogenic evolution of the Andes of southeastern Perú: Economic Geology, v. 85, p. 1520-1583. Clark, A.H., Tosdal, R.M., Farrar, E., and Plazolles V., A., 1990b, Geomorphologic environment and age of supergene enrichment of the Cuajone, Quellaveco, and Toquepala porphyry copper deposits, southeastern Peru: Economic Geology, v. 85, p. 1604-1628. Coira, B., Davidson, J., Mpodozis, C., and Ramos, V., 1982, Tectonic and magmatic evolution of the Andes of northern Argentina and Chile: Earth Science Reviews, v. 18, p. 302-332. Concha, D. and Valle, J., 1999. Prospeccion, Exploracion y Desarrollo del Yacimiento Cuajone: Bol. Primer Vol. Mono. Yacimientos Peruanos: Pro Explo 1999, v. 2, p. 117-143. Davidson, J., and Mpodozis, C., 1991. Regional geologic setting of epithermal gold deposits, Chile. Economic Geology, v. 86, p. 1174-1186. Decou, A., vn Eynatten, H., Mamani, M, Sempere, T., and Wörner, G., 2011, Cenozoic forearc basin sediments in southern Peru (15-18°S): Stratigraphy and heavy mineral constraints for Eocene and Miocene evolution of the Central Andes: Sedimentary Geology, v. 237, p. 55-72.

Demouy, S., Paquette, J.-L., de Saint Blanquat, M., Benoit, M., Belousova, E.A., O’Reilly, S.Y., Garcia, F., Tejada, L.C., Gallegos, R., and Sempere, T., 2012, Spatial and temporal evolution of Liassic to Paleocene arc activity in southern Peru unraveled by zircon U-Pb and Hf in-situ data on plutonic rocks: Lithos, v. 155, p. 183-200. Eichelberger, N., McQuarrie, N., 2015, Kinematic reconstruction of the Bolivian orocline: Geopshere, v. 11, no. 2, p. 445562. Estrada, F., 1975, Geologia del Quellaveco: Boletin de la Sociedad Geologica del Perú, v. 46, p. 65-86. Guerrero, T., and Candiotti, H., 1979, Ocurrencía de monzonita profirítica y zonamiento alteración-mineralización en el stock de granodiorita-Quellaveco: Boletin de la Sociedad Geologica del Perú, v. 63, p. 69-79. Gustafson, L.B., and Hunt, J.P., 1975, The porphyry copper deposit at El Salvador, Chile: Economic Geology, v. 70, p. 857912. Hollings, P., Cook, D., and Clark, A., 2005, Regional geochemistry of Tertiary igneous rocks in central Chile: Implications for the geodynamic environment of giant porphyry copper and epithermal gold mineralization: Economic Geology, v. 100, pp. 887-904. Injoque, J., 1997, Yacimientos de Cu tipo manto: mineralizaciones economicas producto de sistemas geothermales mesozoicos andinos, relacionadas al metamorfismo regional, volcanismo y ambiente geotectonico: IX Congresso Peru Geologica, Resumes Extendido, p. 45-49. Injoque-Espinoza, J., 2002, Fe oxide-Cu-Au deposits in Peru: an integrated view, in Porter, T.M., ed., Hydrothermal iron oxide copper-gold & related deposits: A global perspective: Linden Park, Australia, PGC Publishing, v. 2, p. 97-114. Isacks B. L., 1988, Uplift of the central Andean plateau and bending of the Bolivian orocline. Journal of Geophysical Research, v. 93, p. 3211-3231. Jacay, J., Semperé, T., Husson, L. and Pino, A., 2002, Structural characteristics of the Incapuquio Fault System, southern Peru: 5th International Symposium on Andean Geodynamics, p. 319-321. Jaillard, E., Hérail, G., Monfret, T., DíazMartínez, E., Baby, P., Lavenu, A., and 4

Dumont, J.F., 2000, Tectonic evolution of the Andes of Ecuador, Peru, Bolivia and northernmost Chile, in Cordani, U.G., Milani, E.J., Filho, T., and Campos, D.A., eds. Tectonic evolution of South America: 31st International Geologic Congress, Rio de Janeriro, Brazil, Proceedings, p. 481559. James, D.E., 1982, A combined, O, Sr, Nd, Sr isotopic and trace element study of crustal contaimination in central Andea lavas. 1: Local geochemical varioations: Earth and Planetary Science Letters, v. 57, p. 47-62. James, D.E., and Sacks, I.S., 1999, Cenozoic formation of the Central Andes: A geophysical perspective, in Skinner, B.J., ed., Geology and Ore Deposits of the Central Andes. Society of Economic Geologist Special Publication, no. 7, p. 125. Jenks, W.F., 1948, Geología de la Hoja de Arequipa: Boletin de la Instituto Geologica Perú, v. 9, Jones, P.R., III, 1981, Crustal structures of the Peru continental margin and adjacent Nazca Plate 9°S latitude: Geological Society of America Memoir 154, p. 423443. Kay, S.M., and Mpodozis, C., 2001), Central Andean ore deposits linked ot evolving shallow subduction systems and thickening crust: GSA Today, v. 11, no. 3, p. 4-9 Kihien, A., 1975, Alteración y sus relación con la mineralización en el pórfido de cobre de Cerro Verde: Boletin de la Sociedad Geológíca del Perú, v. 46, p. 103-126. Kihien, A., 1995, Geología, génesis de la mineralización-alteración y evolución de los fluiídos hidrotermales en el porfido de cobre de Quellaveco: Sociedad Geologica del Perú, vol. Jubilar Alberto Benavides, p. 159-178. Lacy, W.C. 1958, Porphyry copper deposit, Cuajone, Peru: American Institute of Mining, Metallurgy, and Petroleum Engineers Transactions, v. 11, p. 104-107. Lacy, W.C., 1991, Discovery and development of the Toquepala and Cuajone deposits, Peru, in Hollister, V.F., ed., Porphyry copper, molybdenum, and gold deposits, volcanogenic deposits (massive sulfides), and deposits in layered rock: Soc. Min., Metal., and Explor., v. 3, p.53-61. Le Bel, L.M., 1985. Mineralization in the Arequipa segment: the porphyry-Cu deposit of Cerro Verde/Santa Rosa, in

Pitcher, W.S., Atherton, M.P., Cobbing, E.J., and Beckinsale, R.D., eds., Magmatism at a plate edge: The Peruvian Andes: Glasgow, Blackie, John Wiley and Sons, p. 250-260. Loewy, S.L., Connelly, J.N., Dalziel, I.W.D., and Gower, C.F., 2003, Eastern Laurentia in Rodinia: constraints from whole rock Pb and U/Pb geochronology: Tectonophysics, v. 375, p. 169–197. Loewy, S.L., Connelly, J.N., and Dalziel, I.W.D., 2004, An orphaned basement block: the Arequipa-Antofalla Basement of the central Andean margin of South America: Geological Society of America Bulletin, v. 116, p. 171-187. Mamani, M., Tassara, A., and Wörner, G., 2008, Composition and structural control of crustal domains in the central Andes: Geochemistry, Geophysics, Geosystems, G3, v. 9, Q03006, doi:10.1029/2007GC001925. Mamani, M., Wörner, G., and Sempere, T., 2010, Geochemical variation in igneous rocks of the Central Andean orocline (13° to 18°): Tracing crustal thickening and magma generation through time and space: Geological Society of America Bulletin, v. 122, no. 1/2, p. 162-182. Manrique J., and Plazolles, A., 1975, Geología de Cuajone: Boletin de la Sociedad Geologica del Perú, v. 46, p. 137-150. Marschik, R., and Fontbote, Lluis, 2002, The Candelaria-Punta del Cobre iron oxide Cu-Au(-Zn-Ag) deposits, Chile: Economic Geology, v. 96, p. 1799-1826. Martignole, J., and Martelat, J.E., 2003, Regional-scale Grenvillian-age UHT metamorphism in the Mollendo–Camana block (basement of the Peruvian Andes): Journal of Metamorphic Geology, v. 21, p. 99–120. Martínez, W., and Cervantes, J., 2003, Rocas ígneas en el sur del Perú: Nuevos datos geocronométricos, geoquímicos y estructurales entre los paralelos 16° y 18°30′S: Lima, Peru, INGEMMET, Boletínes, serie D, v. 26, 140 p. Mattos, M. and Valle, J. 1999. Prospeccion, exploracion y desarrollo del yacimiento Toquepala, in Bol. Primer Volumen de Monografías de Yacimientos Peruanos: Pro Explo 1999, v. 2, p. 101-116. Mukasa, S.B., 1986, Zircon U-Pb ages of super-units in the coastal batholith, Perú: Geol. Soc. Am. Bull., v. 97, p. 241-254. Mukasa,S . B., and Henry, D. J., 1990, The 5

San Nicolás batholith of coastal Peru: Early Paleozoic continental arc or continental rift magmatism: Geological Society of London,v . 147, p. 27-40. Narváez, S., 1964, Geología de los cuadrangulos de Ilo y Locumba (Hojas 36t y 36-u): Peru Comision Carte Geologica Nacional Boletin 7, 75 p. Noble, D.C., McKee, E.H., Eyzaguirre, V.R., and Marocco, R., 1984, Age and regional tectonic and metallogenetic implications of igneous activity and mineralization in the Andahuaylas-Yauri belt of southern Peru: Econ. Geol. v. 79, p. 172-176. Perelló, J., Carlotto, V., Zárate, A., Ramos, P., Posso, H., Heyra, C., Caballero, A., Fuster, N., and Muhr, R., 2003, Porphyrystyle alteration and mineralization of the middle Eocene to early Oligocene Andahuaylas-Yaui belt, Cusco region, Peru: Economic Geology, v. 98, p. 15751605. Phelps Dodge Mining Company, 2002, Geologia de las porfidos de cobre Cerro Verde y Santa Rosa: Arequipa, Peru, Sociedad Minera Cerro Verde S.A., unpublished report, 21 p. Pitcher, W.S., Atherton, M.P., Cobbing, E.J., and Beckinsale, R.D., eds., 1985, Magmatism at a plate edge: The Peruvian Andes: Glasgow, Blackie, John Wiley and Sons, 328 p. Quang, C.X., Clark, A.H., Lee, J.K.W., and Guillén–B., J, 2003, 40Ar-39Ar ages of hypogene and supergene mineralization in the Cerro Verde – Santa Rosa porphyry Cu-Mo cluster, Arequipa, Peru: Economic Geology, v. 98, p. 1683-1696. Quang, C.X., Clark, A.H., Lee, J.K.W., and Hawkes, N., 2005, Response of supergene processes to episodic Cenozoi uplift, pediment erosion, and ignimbrite eruption in the Porphyry copper Province of southern Perú: Economic Geology, v. 100, p. 87-114. Ramos, V., 2008, The basement of the Central Andes: The Arequipa and related terranes: Annual Review of Earth and Planetary Sciences: v. 36, p. 289-324. Ramos, V.A., 2011. Anatomy and global context of the Andes: Main geologic features and the Andean orogenic style: Geological Society of America Memoirs, v. 204, p. 31-65. Richard, K., and Courtright, H.W., 1958, Geology of Toquepala, Peru: Mining Engineering, v. 10, p. 262-266.

Richards, J.P and Kerrich, R., 2007, Special paper: Adakite-like rocks: Their diverse origins and questionable role in metallogenesis, Economic Geology, v. 102, no. 4, pp. 537-576. Richards, J.P., Spell, T., Rameh, E., Razique, A., and Fletcher, T. 2012. High Sr/Y magmas reflect arc maturity, high magmatic water content, and porphyry Cu ± Mo ± Au potential: Examples from the Tethyan arcs of central and eastern Iran and western Pakistan. Economic Geology, v. 107, p. 295–332. Roperch, P., Semperé T., Macedo, O., Arriagada, C., Fornari, M., Tapa, C., Garcia, M. and Laj, C. 2006, Counterclockwise rotation of Late EoceneOligocene forearc deposits in southern Peru and its significance for oroclinal bending in the Central Andes: Tectonics, v. 25 TC3010, doi: 10.1029/2005TC001882. Sandeman, H.A., Clark, A.H., and Farrar, E., 1995, An integrated tectono-magmatic model for the evolution of the southern Peruvian Andes (13-20°S) since 55 Ma: International Geology Review, v. 37, p. 1039-1073. Satchwell, P.C., 1983, Geología de la mina Cuajone: Boletin de la Sociedad Geologica del Perú, v. 72, p. 127-146. Sébrier, M., Mercier, J.L., Mégard, F., Laubacher, G., Carey-Gailhardis, E., 1985, Quaternary normal and reverse faulting and the state of stress in the central Andes of south Peru: Tecotnics, v. 4, p. 739-780. Sempere, T., Carlier, G., Soler, P., Fornari, M., Carlotto, V., Jacay, J., Arispe, O., Néraudeau, D., Cárdenas, J., Rosas , S., and Jiménez, N., 2002, Late Permian– Middle Jurassic lithospheric thinning in Peru and Bolivia, and its bearing on Andean-age tectonics: Tectonophysics, v. 345, p. 153–181, doi: 10.1016/S00401951(01)00211-6. Sempere, T., and 18 coauthors, 2004, Sistemas transcurrentes de escala lithosférica en el sur del Perú: Sociedad Geologica del Peru, Publicación Especial No. 5, p. 105-110. Shackleton, R.M., Ries, A.C., Coward, M.P., and Cobbold, P.R., 1979, Structure, metamorphism and geochronology of the Arequipa massif of coastal Peru: Journal of the Geological Society London, v. 136, p.195–214. 6

Sillitoe, R.H., 2005, Supergene oxidized and enriched porphyry copper and related deposits: Economic Gology 100th anniversary volume, p. 723-768. Sillitoe, R.H., and Perelló, J., 2005, Andean copper province: Tectonomagmatic settings, deposit types, metallogeny, exploration, and Discovery: Economic Gology 100th anniversary volume, p. 845– 890. Sillitoe, R.H., and Mortensen, J.K., 2010, Longevity of porphyry copper formation at Quellaveco, Peru: Economic Geology, v. 105, p. 1157-1162. Simmons, A.T., 2013, Magmatic and hydrothermal stratigraphy of Paleocene and Eocene porphyry Cu-Mo deposits in southern Peru: Vancouver, Canada, Ph.D. thesis, 305 p. Simmons, A., Tosdal, R.M., Wooden, J.L., Mattos, R., Concha, O., McCracken, S., Beale, T., 2013, Punctuated magmatism associated with Paleocene to Eocene porphyry Cu deposits of southern Peru: Economic Geology, v. 108, p. 625-630. Sociedad Minera Cerro Verde S.A., 2007, Visita Técnica Pro-Explo 2007: Field trip presentation, 40p Soler, P., Grandin, G., and Fornari, M., 1986, Essai de synthèse sur la métallogénie du Perou: Géodynamique, v. 1, p. 33-68. Southern Peru Copper Corporation, 2007a, Cuajone: Field trip presentation, 108p. Southern Peru Copper Corporation, 2007b, Potencial del recurso geologico en la mina Toquepala: Field trip presentation, 38p. Stegan, R., 2014, The Cerri Verde porphyry Cu-Mo deposit, Peru: Hypogene and supergene mineralization: PDAC abstract, 1 p. Tassinari, C.C.G., Castroviejo, R., Rodrigues, J.F., Acosta, J., Pereira, E., 2011. A Neoproterozoic age for the chromitite and gabbro of the Tapo ultramafic massif, Eastern Cordillera, Central Peru and its tectonic implications. Journal of South American Earth Sciences 32, 429–437. Torpoco, C., 1979, Petrograpfía, alteraciones y mineralización del yacimiento de Quellaveco—Moquegua: Boletin de la Sociedad Geologica del Perú, v. 63, p. 117-134. Tosdal, R.M., 1996, The Amazon–Laurentian connection as viewed from Middle Proterozoic rocks in the central Andes, western Bolivia and northern Chile Tectonics, v. 15, p. 827–42

Tosdal, R.M., Clark, A.H., and Farrar, E., 1981, K-Ar geochronology of the late Cenozoic volcanic rocks of the Cordillera Occidental, southernmost Peru: Journal of Volcanology and Geothermal Research, v. 10, p. 157-173. Tosdal, R.M., Clark, A.H., and Farrar, E., 1984, Cenozoic polyphase landscape and tectonic evolution of the Cordillera Occidental, southernmost Peru: Geol. Soc. Am. Bull., v. 95, p. 1318-1332. Valdivia, V., Toro, J.C., Mamani, M., and Terán, J.C., 2014, Chipispaya: Porfido CuAu del Miocene inferior en el sur de Peru: XVII Congresso Peruano de Geologia, 4p. Vicente, J.-C., 1989, Early Late Cretaceous overthrusting in the western cordillera of southern Perú, in Ericksen, G.E., Canas Pinochet, M.T.,and Reinemund, J.A., eds., Geology of the Andes and its relation to hydrocarbon and mineral resources: Houston, Texas, Circum-Pacific Council for Energy and Mineral Resources Earth Science Series, v. 11, p. 81-117. Vila, T., Lindsay, N., and Zamora, R., 1996, Geology of the Manto Verde copper deposit, northern Chile: a specularite-rich, hydrothermal –tectonic breccia related to the Atacama fault zone, in Camus, F., Sillitoe, R.H., and Petersen, R., eds., Andean copper deposits: New Discoveries, Mineralization, Styles and Metallogeny: Society of Economic Geologists Special Publication no. 5, p. 157-169. Wasteneys, A.H., Clark, A.H., Farrar, E., and Langridge, R.J., 1995, Grenvillian granulite-facies metamorphism in the Arequipa massif, Peru: a LaurentiaGondwana link: Earth and Planetary Science Letters, v. 132, p. 63–73. Winter, L. Tosdal, R.M., Franklin, J., and Tegart, P 2004, A reconstructed Cretaceous depostional setting for giant volcanogenic massive sulfide deposits at Tambogrande, northwestern Peru: Society of Economic Geologists Special Publication no. 11, p. 319-340. Wörner, G., Lezaun, J., Beck, A., Heber, V., Lucassen, R., Zinngrebe, E., Rössling, R., and Wilke, H.G., 2000, Precambrian and Early Paleozoic evolution of the Andean basement at Belen (northern Chile) and Cerro Uyarani (western Bolivia Altiplano): Journal of South American Earth Sciences, v. 13, p. 717-737. Wilson, J.J., 1983, Cretaceous stratigraphy of central Andes of Peru: Bull. American 7

Association of Petroleum Geologists, v. 47, p. 1-34. Wilson, J.J., 2000, Structural development of the northern Andes of Peru: X Congresso Peru, Geologica, volumen presentacion. Zweng, P.L., and Clark, A.H., 1996, Hypogene evolution of the Toquepala porphyry copper-molybdenum deposit, Moquegua, southern Peru, in Pierce, F.W., and Bolm, J.G., eds., Porphyry copper deposits of the American Cordillera: Tucson, Arizona Geological Society Digest 20, p. 566-612.

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