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.

The Rhodope-Serbo-Macedonian massif in northern Greece and southern Bulgaria represents a world-class case to study exhumation processes in an extensional back-arc setting, looking at supra-detachment basin formation, contemporaneous magmatism, and gold mineralization, analogous to the Basin and Range Province of the western United States and elsewhere. This field trip examined four different magmatic-hydrothermal systems in the Rhodope metallogenetic province. The guidebook contains five papers that describe the characteristics of the selected systems, including detailed guides for each day of the four-day field trip.

The Rhodope-Serbo-Macedonian massif in northern Greece and southern Bulgaria represents a world-class case to study exhumation processes in an extensional back-arc setting, looking at supra-detachment basin formation, contemporaneous magmatism, and gold mineralization, analogous to the Basin and Range Province of the western United States and elsewhere. This field trip examined four different magmatic-hydrothermal systems in the Rhodope metallogenetic province. The guidebook contains five papers that describe the characteristics of the selected systems, including detailed guides for each day of the four-day field trip.

Abstract The Little Whiteman prospect is located in the western part of the historic Fortymile mining district of the Yukon-Tanana Uplands of east-central, Alaska. The prospect consists of steeply dipping Zn-Pb-Ag-(Cu) massive and semimassive sulfide chimneys and mantos that replace marbles of the greenschist-grade Nasina assemblage of the Yukon-Tanana terrane. A prominent northeast-trending, sinistral strike-slip fault and accessory structures occur within a complex structural zone referred to as the Kechumstuk fault. Normal dip-slip displacement on the southeast-dipping Kechumstuk fault juxtaposed unreactive metavolcaniclastic footwall rocks adjacent to reactive hanging-wall carbonate rocks. Transtension along the Kechumstuk fault has resulted in left-lateral dilation at the northern part of the Little Whiteman prospect. Hydrothermal fluids were channelized along the Kechumstuk fault and vertically restricted by an overlying quartz diorite sill. Hydrothermal alteration ranges from dolomitization of the marble near fault contacts to a distal siliceous zone often containing abundant manganese-oxide stockwork veinlets. Acidic and partly oxidized hydrothermal fluids caused strong local alteration of porphyry dikes, resulting in a muscovite, quartz, pyrite, and kaolinite mineral assemblage. Sulfide bodies extend for >700 m along strike and to depths >300 m. Replacement-style sulfide deposition is localized near and along contacts of steeply dipping structures and felsic porphyry dikes. The sulfide-rich replacement bodies display a sulfide mineral paragenesis of early iron- and subordinate arsenic-bearing sulfide minerals, followed by zoned sphalerite with iron-rich margins containing abundant chalcopyrite inclusions. Continued sulfide mineral precipitation formed a galena and sulfosalt mineral assemblage that became increasingly silver rich through time. Most silver resides in tetrahedrite, which forms inclusions in galena or in late-stage carbonate-sulfide veinlets. Mineralization at the Little Whiteman prospect is interpreted to be the result of hydrothermal fluids driven by Late Cretaceous volcanism. The spatial relationship between the sulfide bodies and felsic porphyry dikes suggest they are related and, perhaps time equivalent to the adjacent Middle Fork caldera that has an age of 69 Ma.