Tectonics and Metallogeny of the Tethyan Orogenic Belt
The Tethyan orogenic belt stretches from the Alps, through the Carpathians and Balkans, Taurides and Caucasus, Zagros, Makran, and Himalayas, to Indochina and into the southwest Pacific Ocean. It represents a complete Wilson Cycle, from opening and closure of the Paleotethys Ocean in the mid-Paleozoic to the Late Triassic, opening of the Neotethys Ocean in the Permian-Early Triassic, and its progressive closure throughout the late Mesozoic and Cenozoic eras. The current state of the orogen includes all stages of convergence from active subduction beneath the Makran and eastern Mediterranean, through advanced continental collision in the Caucasus/Taurides and Zagros, to syn- to postcollisional readjustment in the Carpathians, Balkans, Himalayas, and Indochina (Richards, 2015).
The region has been the focus of significant recent attention from geologists interested both in its tectonic evolution and metallogeny, made possible by increased accessibility to many of the geographic sections of the orogen. Key breakthroughs in understanding its tectonic history have come through improved geochronological techniques and expansion of the database of samples and events dated, combined with more accurate paleogeographic and tectonic models. In parallel, an improved understanding of the subtle relationships between tectonomagmatic and metallogenic processes have refined interpretations that were once based on simplistic assumptions (e.g., that porphyry deposits only form above active subduction zones). Indeed, economic geologists have been among the key drivers of these advances by demanding more accurate and predictive tectonomagmatic models for ore formation that can reliably inform mineral exploration.
Consequently, the Tethyan orogen is now understood to be the best preserved global example of a collisional orogen, where all stages of convergence can be observed in real or recent geological time, and the detailed relationships to ore formation, commonly reflecting tectonic changes measured on submillion-year timescales, can be accurately documented and modeled.
In this volume, we present a selection of papers that showcase this advancement in knowledge, with examples from Eastern Europe to South Asia.Beginning in the Balkans, Knaak et al. (2016) describe the variety of mineral deposits that occur in the emergent worldclass Timok region of eastern Serbia. The origin of the Late Cretaceous Timok Magmatic Complex remains debated, but the authors propose that arc magmatism was focused by dextral transtensional structures, followed by complex structural rearrangement in the Cenozoic. Porphyry Cu-Au deposits, polymetallic replacement deposits, and sedimentary rockhosted Au deposits occur in close spatial, and possibly genetic, relationship to the Late Cretaceous arc rocks. A key contribution of this study is the detailed reconstruction of later Cenozoic fault movements that led to structural dislocation and oroclinal bending, complicating geologic and metallogenic correlations in the region.
Magmatic and Metallogenic Framework of Au-Cu Porphyry and Polymetallic Carbonate-Hosted Replacement Deposits of the Kassandra Mining District, Northern Greece
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Published:January 01, 2016
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CiteCitation
Chris R. Siron, John F. H. Thompson, Tim Baker, Richard Friedman, Pavlos Tsitsanis, Sally Russell, Scott Randall, Jim Mortensen, 2016. "Magmatic and Metallogenic Framework of Au-Cu Porphyry and Polymetallic Carbonate-Hosted Replacement Deposits of the Kassandra Mining District, Northern Greece", Tectonics and Metallogeny of the Tethyan Orogenic Belt, Jeremy P. Richards
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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.
- absolute age
- carbonate rocks
- carbonates
- Cenozoic
- Chalkidiki
- copper ores
- dates
- Europe
- faults
- gold ores
- granodiorites
- Greece
- Greek Macedonia
- igneous rocks
- intrusions
- lead ores
- lead-zinc deposits
- Macedonia
- magmatism
- metal ores
- metallogeny
- mineral deposits, genesis
- Miocene
- Neogene
- Oligocene
- Paleogene
- plutonic rocks
- polymetallic ores
- porphyry copper
- sedimentary rocks
- Serbo-Macedonian Massif
- silver ores
- Southern Europe
- stocks
- structural controls
- Tertiary
- U/Pb
- zinc ores
- northern Greece
- Mavres Petres Deposit
- Olympias Deposit
- Madem Lakkos Deposit
- Kassandra mining district
- Tsikara Deposit
- Stratoni fault zone