Abstract A northerly trending zone of porphyry Cu-Au, porphyry Au, polymetallic replacement Pb-Zn-Au-Ag, and sedimentary rock-hosted Au deposits along the northwest margin of the Late Cretaceous Timok Magmatic Complex forms a part of the Bor metallogenic zone in eastern Serbia. The porphyry Cu-Au, epithermal quartz-alunite, and polymetallic replacement deposits in the northwest margin of the Complex represent parts of zoned magmatic-hydrothermal systems that are linked to Late Cretaceous oxidized, hornblende-biotite diorite porphyry intruded over a ~5- to 6-m.y. period between 83.6 ± 0.5 and 78.5 ± 1.3 Ma (U-Pb SHRIMP-RG ages on zircon), making them slightly younger than the larger Late Cretaceous (89-83 Ma) porphyry Cu-Au and high-sulfidation Cu-Au deposits in the eastern part of the Complex. The low-temperature sedimentary rock-hosted Au deposits in the northwest lie spatially near to, but are always separated by faults from, the polymetallic replacement and porphyry Cu-Au deposits. However, the common but not ubiquitous spatial association between the sedimentary rock-hosted Au deposits and the zoned porphyry Cu polymetallic replacement deposits, coupled with available exploration geochemical vectors evident in soil geochemistry, does suggest a genetic linkage between all the hydrothermal deposits. An important component required to fit the deposit types into a zoned magmatic hydrothermal model is a revised geologic and tectonic understanding that can also be extended to the entire Timok Magmatic Complex. A component of the revised model emphasizes the role of the Cenozoic faults formed during oroclinal bending of the region. Two fault generations are significant. Postmineral easterly trending normal faults bounding basins filled largely by early Miocene sedimentary rocks preserved the low-temperature sedimentary rock-hosted Au deposits and helped preserve deposits in the eastern area of the Complex. These faults accommodated elongation of the Complex and are kinematically linked to dextral strike-slip faults, such as the Timok-Cerna fault system, with as much as 100 km of displacement. Major, postmineral, NW-trending faults dismembered deposits in the northwest and accommodated sinistral displacement, which on a larger scale facilitated rotation between large crustal blocks, as well as Timok Magmatic Complex-scale shortening normal to the Complex during oroclinal bending of the region. The end result of the postmineral deformation during oroclinal bending and extensional and strike-slip deformation is preservation of different crustal levels, not just in the northwest but also throughout the region. The deformation furthermore enhanced the preservation of Cretaceous ore deposits beneath younger rocks. Because the Complex was constructed over a highly faulted Variscan and older basement terrane, it is possible that reactivation of the pre-Cretaceous basement faults in the basement beneath the Complex, such as the Variscan Blagojev-Kamen-Rudaria fault systems, played a role in the Late Cretaceous history of the Bor metallogenic zone, as well as controlling post-Cretaceous deformation in the Complex.

Abstract The Kassandra mining district in the eastern Chalkidiki Peninsula of northern Greece contains ~12 Moz Au in porphyry and polymetallic carbonate-hosted replacement sulfide orebodies. Zircon U-Pb geochronology defines two distinct magmatic episodes in the late Oligocene (27-25 Ma) and early Miocene (20-19 Ma). Both suites are characterized by high K calc-alkaline magmas with the younger early Miocene porphyritic stocks and dikes having indications of shoshonitic geochemistry. Normalized rare earth element patterns support plagio-clase fractionation among the late Oligocene suite, whereas amphibole or garnet fractionation is more likely for early Miocene porphyries. Carbonate replacement mineralization is hosted in marble contained within the semibrittle Stratoni fault zone. Mineralization varies along the 12-km strike length of the fault zone from Cu-bearing skarn adjacent to the late Oligocene Stratoni granodiorite stock westward into Au-Ag-Pb-Zn-Cu carbonate replacement deposits at Madem Lakkos and Mavres Petres. Piavitsa, at the western end of the exposed fault zone, hosts siliceous Mn-rich replacement bodies associated with crustiform Au-rich quartz-rhodochrosite veins. Structural and alteration relationships suggest that carbonate replacement mineralization is syn- to postemplacement of the late Oligocene Stratoni granodiorite stock at 25.4 ± 0.2 Ma. The Olympias Au-Ag-Pb-Zn carbonate replacement deposit, located north of the Stratoni fault zone, is hosted in marble and associated semibrittle structures. Olympias is broadly similar to the Madem Lakkos and Mavres Petres deposits. Early Miocene Au-Cu mineralization at Skouries is associated with a narrow pipe-shaped multiphase porphyry stock emplaced into the hinge zone of a regional antiform. Late Oligocene and early Miocene magmatism overlaps spatially within the district but defines distinct petrogenetic events separated by about 5 m.y. Carbonate replacement massive sulfide deposition was largely controlled by an extensional structure and receptive host rocks within the fault zone, whereas a major regional fold axis localized the Skouries porphyry system. The change in character of mineralization with time may reflect a combination of factors including preexisting structural control, magmatic-hydrothermal processes, and the availability of reactive host rocks.

Abstract The Kişladağ porphyry gold deposit (16.8 Moz) is located in western Anatolia, Turkey, and is hosted in a nested complex of monzonite porphyries that intruded coeval volcanic rocks of the Beydagi stratovolcano and the Menderes metamorphic basement. The intrusions and volcanic rocks have a high K calc-alkaline to shoshonitic affinity similar to the regional volcanic rocks of western Anatolia. Three main intrusive phases are recognized with average gold grades highest in the early intrusions, Intrusion 1 (~0.8 g/t Au) and Intrusion 2 (~0.7 g/t Au), followed by the weakly mineralized Intrusion 3 (typically <0.2 g/t Au). The highest gold (~0.84 g/t) is also associated with the higher temperature potassic (biotite-K feldspar ± actinolite) core of the deposit in Intrusion 1. Molybdenum is most closely associated with Au, whereas the Cu concentration on average is unusually low (~200 ppm) but increases with depth (500-1,000 ppm). Surrounding and partly overlapping the potassic zone is a distinct tourmaline-white mica (± pyrite ± albite ± quartz) alteration with tourmaline abundant up to 500 m from the center of the deposit. White mica is more widely distributed with compositions varying from proximal muscovite-paragonite to distal phengite. Stockwork veinlets are common within the potassic and tourmaline-white mica zones and evolve from volumetrically minor quartz-rich, to quartz-pyrite, to quartz-pyrite with tourmaline envelopes, to the most abundant pyrite-tourmaline veins and breccias, and finally pyrite-only veins. A poorly mineralized advanced argillic alteration assemblage (quartz-alunite ± dickite ± pyrophyllite ± pyrite) postdates the tourmaline-white mica alteration and is particularly abundant in the eastern flank of the deposit and as a lithocap. The most widespread alteration is argillic comprising kaolinite ± smectite ± pyrite ± quartz, and overprinting all alteration phases, and is particularly widespread in the surrounding volcanic package. New geochronological results from the Kisladag deposit constrain the timing and duration of the main gold mineralization stage to <0.4 m.y. (14.76 ± 0.01-14.36 ± 0.02 Ma). The system evolved in the following sequence: (1) Intrusion 1 (>14.76 ± 0.01 Ma), (2) Intrusion 2 (14.76 ± 0.01 Ma), (3) potassic alteration coeval with mineralization (14.4 ± 0.1 Ma), and (4) Intrusion 3 (14.36 ± 0.02 Ma). The deposition of gold is constrained by the emplacement of the sulfide mineralization dated at 14.49 ± 0.06 Ma by Re-Os on molybdenite. The Kişladağ deposit is classified as a gold-only porphyry deposit due to its exceptionally low Cu/Au ratio («0.03). There are few economically significant global analogues—examples include the Maricunga porphyry deposits (9.8 Moz Au) in Chile and La Colosa (33.2 Moz Au) in Columbia. The low Cu/Au ratio may in part be related to the shallow level of emplacement (<1 km?) but also reflects the postcollisional setting. The deposit formed at least 50 m.y. after closure of the northern Neotethys ocean that was related to Cretaceous collision and compression, and 15 m.y. after the commencement slab roll-back of the southern Neotethys ocean and the onset of upper plate extension in the late Eocene to early Oligocene. The Miocene volcanic rocks that host Kisladag are in part related to a slab tear that resulted in upwelling of asthenospheric mantle, which melted previously metasomatized subcontinental lithospheric mantle. Postcollision extension, fertile upper mantle, shallow subduction, and slab tear-induced magmatism, and shallow level of emplacement may have been important factors in the gold-rich nature of Kisladag.

Abstract The Biga Peninsula in northwestern Turkey hosts a large number of high- and low-sulfidation epithermal gold-silver-(copper) and associated copper-gold porphyry deposits and prospects, associated with voluminous, Eocene-Miocene calc-alkaline volcanism and plutonism. In this area, 50 to 20 Ma intermediate to felsic volcanic and volcaniclastic strata overlie metamorphosed basement rocks of the Camlica Group. The volcanic sequence is variably altered over an area covering several hundreds of square kilometers, including argillic, advanced argillic, and massive to vuggy residual quartz alteration, the latter present at the tops of many of the higher elevation peaks in the area. Moderate- and high-angle normal and oblique faults are common in the area and influenced the distribution of mineralization. While gold mineralization associated with these high-sulfidation epithermal systems and flanking low-sulfidation epithermal systems has long been recognized, the existence of porphyry roots to these systems was not fully appreciated until the discovery of the Halilaga porphyry in 2008. In the southern part of the TV Tower property, low relief areas consist of schist and serpentinite intruded by the Kuşçayir pluton, a composite, ~40 Ma intrusion that averages granodiorite in composition. Intermediate volcanic and volcaniclastic rocks are exposed in the highest elevation areas. The northern edge of the pluton, at low to intermediate elevations, consists of at least six intrusions of similar age and composition that differ primarily in degree of porphyritic texture and phenocryst quartz content. The intrusions are parsed into pre- syn- and late mineralization phases with respect to hydrothermal alteration and mineralization related to at least two Au-Cu porphyry centers, Valley and Hilltop. The porphyry systems occur below and are to some degree overprinted by high-sulfidation alteration and mineralization. The porphyry/high-sulfidation system was subjected to weathering and oxidation, giving rise to a supergene copper enrichment blanket that lies near the transition from the high sulfidation into the porphyry environment. Alteration associated with the porphyry systems includes chlorite-magnetite-actinolite, K-feldspar-biotite-quartz-magnetite-hematite (“potassic”), and, at higher elevations, overprinting quartz-muscovite (“phyllic”) alteration. Quartz stockwork veining is ubiquitous in the phyllic and potassic assemblages, and includes quartz-K-feldspar “A” veins, quartz sulfide “B” veins, pyrite-quartz “D” veins, and quartz-magnetite “M” veins. Copper mineral assemblages range from bornite-chalcopyrite to chalcopyrite-pyrite, and chalcopyrite-chalcocite or chalcocite-covellite-digenite in the supergene zones. High-sulfidation epithermal mineralization is dominantly oxidized, and consists of residual vuggy and massive quartz, alunite, pyrophyllite, and iron oxides. New U-Pb dates for the Kuşçayir pluton and Hilltop and Valley intrusions range from 38 to 40 Ma, consistent with other Cu-Au porphyry systems in the region, whereas most dated high-sulfidation epithermal deposits in the region formed at roughly 29 Ma, coeval with an Oligocene suite of intrusions. It is possible that the epithermal-porphyry relationship at Karaayi is one of overprinting of two unrelated hydrothermal systems.

Abstract Epithermal Au-(Ag) and porphyry Cu-Au-(Mo) mineralization of the Biga Peninsula in northwestern Turkey occurs in a district comprised of NE- to ENE-trending metamorphic horst blocks separated by half-graben volcano-sedimentary basins. These developed as a result of rollback of the northward-subducting African slab during the Eocene, Oligocene, and Miocene. We propose that epithermal and porphyry systems occupy distinct, favorable positions within the overall extensional architecture and fault/fracture array. High- and low-sulfidation epithermal alteration systems, along with related quartz veins, preferentially occupy half-graben basins and border faults. These epithermal systems are found above a core complex detachment fault system, forming major strata-bound silicified zones fed by steeply dipping extensional faults and associated fractures above inferred intrusions. At greater depths and higher pressure and temperature conditions, porphyry-style alteration systems are spatially associated with porphyritic stocks that occur in close association with plutonic bodies. These plutons have intruded the footwall of ductile to brittle extensional faults and spatially and temporally link to metamorphic core complex exhumation. Episodic changes in the tectonic stress resulted in pulses of crustal extension that favored porphyry-type and high-sulfidation-style mineralization during mid to late stages of Eocene and Oligocene extensional tectonic phases. On the other hand, the early stages of each extensional phase promoted higher structural permeability, enabling the development of vein systems and low-sulfidation epithermal-style mineralization. Postemplacement crustal extension resulted in “domino-style” block rotations and half-graben formation throughout the Miocene and Pliocene. Since the early Pliocene, the westward propagation of the North Anatolian fault has resulted in dextral transtension in the Biga Peninsula and, as a result, postmineralization structural dismemberment of deposits and alteration systems is common.

Abstract This contribution reviews the metallogenic setting of the Lesser Caucasus within the framework of the complex geodynamic evolution of the Central Tethys belt during convergence and collision of the Arabia-, Eurasia-, and Gondwana-derived microplates. New rhenium-osmium molybdenite ages are also presented for several major deposits and prospects, allowing us to constrain the metallogenic evolution of the Lesser Caucasus. The hostrock lithologies, magmatic associations, deposit styles, ore controls, and metal endowment vary greatly along the Lesser Caucasus as a function of the age and tectono-magmatic distribution of the ore districts and deposits. The ore deposits and ore districts can essentially be assigned to two different evolution stages: (1) Mesozoic arc construction and evolution along the Eurasian margin, and (2) Cenozoic magmatism and tectonic evolution following Late Cretaceous accretion of Gondwana-derived microplates with the Eurasian margin. The available data suggest that during Jurassic arc construction along the Eurasian margin, i.e., the Som-kheto-Karabagh belt and the Kapan zone, the metallogenic evolution was dominated by subaqueous magmatic-hydrothermal systems, VMS-style mineralization in a fore-arc environment or along the margins of a back-arc ocean located between the Eurasian margin and Gondwana-derived terranes. This metallogenic event coincided broadly with a rearrangement of tectonic plates, resulting in steepening of the subducting plate during the Middle to Late Jurassic transition. Typical porphyry Cu and high-sulfidation epithermal systems were emplaced in the Somkheto-Karabagh belt during the Late Jurassic and the Early Cretaceous, once the arc reached a more mature stage with a thicker crust, and fertile magmas were generated by magma storage and MASH processes. During the Late Cretaceous, low-sulfidation-type epithermal deposits and transitional VMS-porphyry-epithermal systems were formed in the northern Lesser Caucasus during compression, uplift, and hinterland migration of the magmatic arc, coinciding with flattening of the subduction geometry. Late Cretaceous collision of Gondwana-derived terranes with Eurasia resulted in a rearrangement of subduction zones. Cenozoic magmatism and ore deposits stitched the collision and accretion zones. Eocene porphyry Cu-Mo deposits and associated precious metal epithermal systems were formed during subduction-related magmatism in the southernmost Lesser Caucasus. Subsequently, late Eocene-Oligocene accretion of Arabia with Eurasia and final closure of the southern branch of the Neotethys resulted in the emplacement of Neogene collision to postcollision porphyry Cu-Mo deposits along major translithospheric faults in the southernmost Lesser Caucasus. The Cretaceous and Cenozoic magmatic and metallogenic evolutions of the northern Lesser Caucasus and the Turkish Eastern Pontides are intimately linked to each other. The Cenozoic magmatism and metal-logenic setting of the southernmost Lesser Caucasus can also be traced southward into the Cenozoic Iranian Urumieh-Dokhtar and Alborz belts. However, contrasting tectonic, magmatic, and sedimentary records during the Mesozoic are consistent with the absence of any metallogenic connection between the Alborz in Iran and the southernmost Lesser Caucasus.

Abstract Iran is a resource-rich country, with large deposits of iron, copper, zinc, and gold, as well as industrial minerals and oil and gas. Most of these resources were formed in response to complex and protracted contractional deformation events related to the subduction and eventual closure of the Neotethys ocean in the late Mesozoic and Cenozoic. Here we focus on porphyry Cu ± Mo ± Au and related epithermal Au deposits, which were once thought to be synonymous with subduction, but are now recognized to also form during collisional and other postsubduction tectonic processes. Recent advances in tectonic and paleogeographic reconstructions, and new geochronological and geochemical data reveal that in fact most of Iran’s major porphyry and epithermal deposits fall into this postsubduction category (e.g., Sungun, Sari Gunay, Meiduk, Sar Cheshmeh). The same applies to several major deposits in neighboring Turkey (e.g., Kişladağ, Çöpler), whereas continued subduction beneath the Makran in western Pakistan accounts for some of the only “normal” subduction-related porphyry deposits in the region (e.g., Saindak, Reko Diq). Few igneous rocks or mineral deposits associated with the Paleotethys ocean occur in Iran, although several Paleozoic ophiolite belts are preserved, and Early Cambrian Kiruna-type iron oxide-apatite deposits are found in the Bafq district of eastern Central Iran. Arc magmatism associated with Mesozoic subduction of the Neotethys ocean is widespread in the Sanandaj-Sirjan zone, but no porphyry or epithermal deposits of this age have been discovered to date, likely due to erosion down to batholithic levels. Arc magmatism shifted to the Urumieh-Dokhtar magmatic arc and the Lut block in the late Paleogene-early Neogene, and the first significant porphyry deposits formed in the Eocene and Oligocene. However, the main period of porphyry formation occurred later in the early to mid-Miocene, synchronous with terminal collision between the Afro-Arabian and Eurasian plates. Several large porphyry Cu (Sungun, Meiduk, and Sar Cheshmeh), as well as the porphyry-related Sari Gunay epithermal Au deposit, were formed at this time (~20–11 Ma) along the length of the orogen. Active subduction continues only beneath the Makran of southeastern Iran and western Pakistan, where the large Saindak (~22 Ma) and Reko Diq (13–10 Ma) porphyry deposits occur. Mineral exploration in Iran to date has been largely restricted to areas of outcrop, but the potential for extensions of known deposits, or “blind” discoveries below widespread Quaternary cover is considered to be high.

Abstract Tectonic, geologic, geochemical, geochronologic, and ore deposit data from the U.S. Geological Survey-led assessment of 26 porphyry belts identified in the central Tethys region of Turkey, the Caucasus, Iran, western Pakistan, and southern Afghanistan relate porphyry mineralization to the tectonomagmatic evolution of the region and associated subduction and postsubduction processes. However, uplift, erosion, subsidence, and burial of porphyry systems, as well as post-mineral deformation, also played an essential role in shaping the observed metallogenic patterns. We present a methodology that systematically evaluates the relationship between the level of erosion, the extent of cover, and the number of known porphyry occurrences in porphyry belts. Porphyry belts that exhibit coeval volcanic-to-plutonic rock aerial ratios between 33 and 66 and limited cover contain numerous identified porphyry occurrences. These belts are relatively well explored because porphyry systems are not eroded or buried. Porphyry belts with volcanic-to-plutonic ratios that are greater than 66, but are modestly covered, contain fewer identified porphyry occurrences. Current exploration in these belts is increasingly identifying porphyry systems under associated epithermal deposits. Porphyry belts that show volcanic-to-plutonic ratios that are greater than 66, but are extensively covered, contain few identified porphyry occurrences. These belts have not been extensively explored but have potential for discoveries under cover. Deformed porphyry belts exhibit variable volcanic-to-plutonic ratios that are typically below 33, but can be as high as 60. Commonly, these deformed belts are extensively covered. Exploration efforts for porphyry deposits in these variably exhumed belts have been limited. Exploration has resulted in the identification of 62.7 million tonnes (Mt) of copper, 2.0 Mt of molybdenum, and 4.200 t of gold in the 45 porphyry deposits contained in the 26 porphyry belts of the region: (1) 54.7 Mt of copper (87% of total), 1.74 Mt of molybdenum (87%), and 3,370 t of gold (80%) occur in the 25 deposits of the four porphyry belts that exhibit coeval volcanic-to-plutonic ratios between 33 and 66 and limited cover; (2) 5.44 Mt of copper (9%), 0.148 Mt of molybdenum (7%), and 581 t of gold (14%) are contained in the 11 deposits of the 11 porphyry belts that display volcanic-to-plutonic ratios greater than 66 and modest cover; (3) 2.08 Mt of copper (3%), 0.110 Mt of molybdenum (6%), and 244 t of gold (6%) occur in the seven deposits of the three porphyry belts that have volcanic-to-plutonic ratios that are greater than 66 and extensive cover; and (4) 0.388 Mt of copper (1%), 0.006 Mt of molybdenum (<<1%), and 6 t of gold (<<1%) are contained in the two deposits of the eight deformed and covered porphyry belts with variable but typically low volcanic-to-plutonic ratios. The central Tethys region is receiving considerable exploration attention. It hosts the Kadjaran (4.6 Mt Cu), Sungun (5.1 Mt Cu), Sar Cheshmeh (8.9 Mt Cu), and Reko Diq (23.0 Mt Cu) world-class porphyry deposits. Continued exploration for porphyry deposits in the region will likely lead to new discoveries in known porphyry belts, particularly under cover and below high- and intermediate-sulfidation epithermal systems.

Abstract A method is presented for integrating structural and alteration interpretations based on regional remote sensing magnetic and infrared spectral data. Integrated interpretations can provide insight about the controls that basement structural architecture exerts over porphyry mineralization. The method is illustrated by a study of the porphyry-endowed Kerman belt of Iran, for which structural interpretations of EMAG2 first vertical derivative magnetic data were refined using alteration lineaments interpreted from Landsat-8 infrared spectral data. This method makes use of regional linear alteration trends indicative of lithologic discontinuities to refine and to enhance the understanding of deep-seated structures interpreted from regional magnetic data. The integrated structural and alteration analysis of the Kerman belt of Iran highlights a first-order fault that is interpreted continuously at depth over approximately 500 km strike length and shows good spatial correlation with the location of most porphyry deposits and prospects. The analysis also allows for the visualization of a premineralization regional dilational zone that hosts the most prolific portion of the Kerman porphyry belt.

Abstract The Reko Diq porphyry cluster in the western Chagai magmatic belt, Pakistan, contains a geologic resource of 5.9 billion tons (5.35 Bt) @ O.41% Cu and O.22 g/t Au, largely in the H14 and H15 porphyry deposits. These two deposits, located approximately 1 km apart, are related to a series of petrologically similar, middle Miocene (12.6–12.O Ma), calc-alkaline porphyry intrusions hosted by Oligocene andesitic volcanic and clastic sedimentary rocks. The porphyry intrusions are characterized by phenocrysts of plagioclase, biotite, quartz, and amphibole in a microcrystalline mafic silicate-bearing quartzofeldspathic groundmass. Potassic, sericite-chlorite, sericitic, and propylitic alteration assemblages are zoned about the porphyry intrusions. The early and intermineral porphyry intrusions are overprinted by a pervasive potassic alteration assemblage composed of hydrothermal biotite-K-feldspar-magnetite ± anhydrite with associated chalcopyrite and bornite. Chalcopyrite, bornite, and lesser pyrite are disseminated or are associated with a stockwork of quartz ± magnetite ± K-feldspar A- and B-type and less common sulfide-only veins. Bornite characterizes a distinct high-grade core to the H14 deposit, but it is less common and always subsidiary in volume to chalcopyrite in the slightly older H15 deposit. Local sulfide mineral assemblages of pyrite-covellite-bornite-chalcopyrite associated with pervasive quartz-sericite alteration assemblages in the H15 deposit form narrow, steeply dipping vein-like zones or strata-bound horizons restricted to felsic tuff or sandstone. The late porphyry intrusions are weakly altered and mineralized, lack volumetrically significant veins, and generally have low Cu and Au concentrations. Sulfide-deficient potassic alteration assemblages at greater than 1,OOO m depth are overprinted by a texturally destructive alteration assemblage of albite-epidote ± actinolite ± chlorite, inferred to represent a sodic-calcic alteration assemblage. Total sulfide contents at these depths are less than 1%. At shallow depths, a sericite-chlorite alteration assemblage overprints potassic alteration mainly along late-stage centimeter-scale chalcopy-rite-pyrite D-type veins. The sericite-chlorite assemblage is much more extensive in the H15 deposit than in the H14 deposit. An outer sericitic alteration assemblage composed of quartz-muscovite-pyrite ± chalcopyrite flanks the sericite-chlorite assemblage. An intermediate argillic alteration assemblage composed of clay minerals (illite, smectite, montmorillonite) and carbonate is common in remnants of plagioclase within the sericite-chlorite and sericitic alteration assemblages. A propylitic alteration assemblage of chlorite-epidote-albite ± pyrite-carbonate is developed in the peripheral volcanic and sedimentary host rocks surrounding the H14-H15 porphyry complex.