Tertiary granitoids of Rhodope, northern Greece: Magmatism related to extensional collapse of the Hellenic Orogen?

doi:10.1016/0040-1951(92)90327-3

Tectonophysics

Volume 210, Issues 3–4, 15 September 1992, Pages 295-314

https://doi.org/10.1016/0040-1951(92)90327-3 Get rights and content

Abstract

Many granites that occur in orogenic belts such as the Himalaya, the Hercynides or Caledonides are thought to result from anatexis of the lower parts of over-thickened thrust-stacked crustal units, just preceding termination of the orogenic cycle. Numerous Tertiary granitoids occur in the Rhodope Zone of northern Greece (and adjacent regions of Bulgaria), a belt regarded as an eastern extension of the Alpine System. These granites could also be regarded as syn- or late-tectonic crustal melts in that some have been emplaced as sheet-like bodies along major Alpine thrust planes, and show a strong marginal foliation parallel to the pervasive Alpine compressional fabrics. In detail, however, the geochemistry of the granitoids, their timing and relationships with country rocks, suggest they have been emplaced in an extensional regime that is related to the collapse of the Hellenic Orogen and, more particularly, to the crustal thinning that the Aegean region has suffered since the mid-Tertiary. Rather than being products of crustal thickening, it is suggested that their petrogenesis is related to the elevation of thermal gradients during the extensional phase, which initiated thermal breakdown of hydrous minerals in the lithosphere and lower crust that had existed metastably during compression and the subduction of cool ocean lithosphere beneath the region in the late Mesozoic-early Tertiary.

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The most significant mineralization styles comprise porphyry, epithermal, carbonate-replacement, reduced intrusion-related gold, intrusion-related Mo-W and polymetallic veins. Porphyry and epithermal deposits are commonly associated with extensive hydrothermal alteration halos, whereas in other cases alteration is of restricted development and mainly structurally controlled. Porphyry deposits include Cu-Au-, Cu-Mo-Au-Re, Mo-Re, and Mo-W variants. Epithermal deposits include mostly high- and intermediate-sulfidation (HS and IS) types hosted in volcanic rocks, although sedimentary and metamorphic rock hosted mineralized veins, breccias, and disseminations are also present. The main metal associations are Cu-Au-Ag-Te and Pb-Zn-Au-Ag-Te in HS and IS epithermal deposits, respectively. Major carbonate-replacement deposits in the Kassandra and Lavrion mining districts are rich in Au and Ag, and together with reduced intrusion-related gold systems played a critical role in ancient economies. Finally hundreds of polymetallic veins hosted by metamorphic rocks in the Rhodopes and Cyclades significantly add to the metal endowment of Greece.

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Tertiary granitoids of Rhodope, northern Greece: Magmatism related to extensional collapse of the Hellenic Orogen?

Abstract

Chem. Geol.

Chem. Geol.

Tectonophysics

J. Struct. Geol.

Tectonophysics

Tectonophysics

Earth Planet. Sci. Lett.

Earth Planet. Sci. Lett.

The Oligocene volcano-sedimentary sequence of the Dipotama Basin, N. Greece: temporal relationships between Tertiary granites and volcanics, and implications for the regional tectonic evolution

Geol. Mijnbouw

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Terra Abstr.

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Geology

The late Alpine evolution of an extensional shear zone, Naxos, Greece

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Instrumental neutron activation analysis —a routine method

Geological setting of part of the western Rhodope Massif

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Neues Jahrb. Mineral. Abh.

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Tectonics

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Alterbestimmungen zum Oligozänen Vulkanismus der Süd-Rhodopen/Nord Griechenland

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Synextensional magmatism in the Basin and Range province

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Geol. Soc. Am. Bull.

Mediterranean back arc basins

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Bull. Volcanol.

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Structure and geodynamic evolution of the Aegean region