Post-collisional Cenozoic extension in the northern Aegean: The high-K to shoshonitic intrusive rocks of the Maronia Magmatic Corridor, northeastern Greece

Abstract

The Maronia Magmatic Corridor is a NE-trending belt of Oligocene plutons that intrudes the Kechros Dome of the northern Rhodope Core Complex in northeastern Greece. The post-collisional magmatism transitions from early high-K calc-alkaline magmatism in the NE to a younger, shoshonitic phase in the SW. We use a full suite of whole-rock geochemical analyses, including rare earth elements, to show a shared metasomatized mantle source of the magmatism. Evidence of plagioclase saturation from the onset of crystallization and amphibole-pyroxene-controlled fractionation in the high-K calc-alkaline magmatism suggest a drier (<4.75 wt% H 2 O) parental magma than is typical of subduction-related magmatism. Continued H 2 O depletion of the metasomatized source mantle resulted in the transition to a shoshonitic trend where deep crustal fractionation of an H 2 O-poor (< ~2 wt% H 2 O) magma in the absence of major olivine resulted in incompatible enrichment over a small range of SiO 2. High-precision U-Pb zircon geochronology is presented here for the first time to provide chronological markers for the transition in the magmatic evolution of the Kechros dome. A 2.2 Myr break in magmatism separates the intrusion of the shoshonitic Maronia pluton at 29.8 Ma from the emplacement of the rest of the high-K calc-alkaline Maronia Magmatic Corridor between 32.9-32.0 Ma. The Maronia pluton is the hottest, driest, and youngest episode of post-collisional magmatism in the Kechros dome; we suggest that the emplacement of Maronia marks the cessation of magmatism in the northern Rhodope Core Complex as asthenospheric mantle upwelling migrated southward.

Trace Elements in Magnetite from the Pagoni Rachi Porphyry Prospect, NE Greece: Implications for Ore Genesis and Exploration

“…Radiometric dating for the monzodiorite yielded ages of 31.9 ± 0.5 Ma (Rb/Sr on biotite, [38]). Recently, Perkins et al [65] provided further geochronological data for the magmatic intrusion in the Kirki area (32.05 ± 0.07 Ma, U-Pb on zircon). Late, NNW-trending microgranite porphyry dikes ( Figure 2) crosscut the aforementioned magmatic rocks and comprise the final intrusive stage in the area [51].…”

A New Porphyry Mo Mineralization at Aisymi-Leptokarya, South-Eastern Rhodope, North-East Greece: Geological and Mineralogical Constraints

“…Recently, Perkins et al [28], extending previous studies of Del Moro et al [24], classified the magmatic rocks of the Maronia-Leptokarya corridor, into two, temporally and geochemically distinct, magmatic complexes, the Kassiteres-Leptokarya magmatic suite and the Maronia plutonic complex respectively. Both complexes comprise magmatic rocks with calc-alkaline to shoshonitic compositions and post-collisional affinities.…”

“…The Leptokarya pluton, forms part of a NE-trending intrusive belt that includes the Kassiteres, Kirki, Leptokarya and Tris Vrisses intrusions ( Figure 1) and consists of quartz monzogabbros/monzodiorites predominantly along with tonalites and granodiorite [24,25,27,28]. Theses intrusive rocks are characterized by a medium-grained, granular to porphyritic texture consisting of plagioclase and variable amounts of pyroxene, amphibole, biotite and Fe-Ti oxides, with quartz and K-feldspar occurring as interstitial minerals.…”

“…Radiometric data (Rb-Sr in biotite) yielded ages of 31.4 ± 0.7 to 31.9 ± 0.5 Ma [24]. Recently, Perkins et al [28] provided a high precision age of 32.235 ± 0.026 Ma, based on Pb-U geochronology, for the Leptokarya pluton.…”

Mineralogical Study of the Advanced Argillic Alteration Zone at the Konos Hill Mo–Cu–Re–Au Porphyry Prospect, NE Greece

“…Available geochronological data for the monzodiorite yielded cooling ages of 31.9 ± 0.5 Ma (Rb/Sr on biotite [49]) and 32.6 ± 0.5 Ma ( 40 Ar/ 39 Ar on biotite [50]). Recently, Perkins et al [51] conducted a U-Pb zircon geochronological study on the Kassiteres magmatic suite, showing that magmatism occurred between 32.05 ± 0.02 and 32.93 ± 0.02 Ma. Previous studies in this area have shown that the granodiorite hosts the Konos Hill porphyry Mo-Cu-Re-Au porphyry prospect [22,26,27].…”