caa a22 4500 467889937 CHVBK 20180406152746.0 cr unu---uuuuu 170328e20060901xx s 000 0 eng 10.1007/s00710-006-0159-z doi (NATIONALLICENCE)springer-10.1007/s00710-006-0159-z Dolomitic marbles from the ultrahigh-pressure metamorphic Kimi complex in Rhodope, N.E. Greece [Elektronische Daten] [E. Mposkos, I. Baziotis, A. Proyer, G. Hoinkes] Summary: Dolomitic marbles from the Organi and Pandrosos areas of the ultrahigh-pressure (UHP) metamorphic Kimi complex in East Rhodope, N.E. Greece have the mineral assemblage: Cal + Dol + Ol + Phl ± Di ± Hbl ± Spl ± Ti-Chu + retrograde Srp and Chl. Several generations of calcite and dolomite with variable composition and texture represent different stages of the P-T evolution: The first stage is represented by matrix dolomite ( ${\rm X}_{\rm MgCO_3}$ = 0.48) and relic domains of homogenous composition in matrix calcite ( ${\rm X}_{\rm MgCO_3}$ = 0.11-0.13); the second stage is evident from precipitation of lath-shaped and vermicular dolomite in matrix calcite. The third stage is represented by veinlets of almost pure CaCO3 and domainal replacement of prior calcite by nearly pure CaCO3 + Ca-rich dolomite ( ${\rm X}_{\rm MgCO_3}$ = 0.34-0.43). Matrix dolomite adjacent to CaCO3 veinlets also becomes Ca-rich ( ${\rm X}_{\rm MgCO_3}$ = 0.42). In fact, Ca-rich dolomites with ${\rm X}_{\rm MgCO_3}$ in the range of 0.40-0.34 are reported for the first time from metamorphic marbles. Coexisting Ca-rich dolomite and Mg-poor calcite cannot be explained by the calcite-dolomite miscibility gap. This assemblage rather suggests that Mg-poor calcite was aragonite originally, which formed together with Ca-rich dolomite according to the reaction Mg-Cal → Arg + Dol (1) at ultrahigh pressures and temperatures above at least 850 °C, when dolomite becomes disordered and incorporates more Ca than coexisting aragonite does in terms of Mg. The simplest explanation of these observations probably is to suggest two metamorphic events: The first one represented by relic matrix carbonates at relatively low to moderate pressures and temperatures of ca. 750 °C, and the second one limited by the minimum temperatures for dolomite disorder (ca. 850 °C) and in the aragonite + dolomite stability field, i.e. at a minimum pressure of 3 GPa and, if the presence of diamond-bearing metapelites nearby is considered, at conditions of at least 850 °C and 4.3 GPa in the diamond stability field. As there is hardly any back-reaction of Ca-rich dolomite + Mg-poor calcite to Mg-rich calcite, peak temperatures remained below the reaction (1) and the exhumation path probably crossed the aragonite-calcite transition at much lower than peak temperature. Cooling and decompression must have both occurred extremely fast in order for the µm-sized Ca-rich dolomite textures to be preserved. An alternative explanation of the formation of "UHP”-textures and compositions is by a fluid influx that not only caused serpentinisation and chloritisation of silicates but also Mg-leaching from carbonates, particularly from Mg-rich calcite and its fine grained dolomite-precipitates, thus transforming them into Mg-poor calcite + Ca-rich dolomite. Springer-Verlag, 2006 Mposkos E. Department of Geological Sciences, School of Mining and Metallurgical Engineering, National Technical University of Athens, Athens, Greece aut Baziotis I. Department of Geological Sciences, School of Mining and Metallurgical Engineering, National Technical University of Athens, Athens, Greece aut Proyer A. Department of Mineralogy and Petrology, Institute of Earth Sciences, Karl-Franzens University, Graz, Austria aut Hoinkes G. Department of Mineralogy and Petrology, Institute of Earth Sciences, Karl-Franzens University, Graz, Austria aut Mineralogy and Petrology Springer-Verlag 88/1-2(2006-09-01), 341-362 0930-0708 88:1-2<341 2006 88 710 https://doi.org/10.1007/s00710-006-0159-z text/html Onlinezugriff via DOI 1 research-article jats NATIONALLICENCE 856 40 https://doi.org/10.1007/s00710-006-0159-z text/html Onlinezugriff via DOI NATIONALLICENCE 700 1- Mposkos E. Department of Geological Sciences, School of Mining and Metallurgical Engineering, National Technical University of Athens, Athens, Greece aut NATIONALLICENCE 700 1- Baziotis I. Department of Geological Sciences, School of Mining and Metallurgical Engineering, National Technical University of Athens, Athens, Greece aut NATIONALLICENCE 700 1- Proyer A. Department of Mineralogy and Petrology, Institute of Earth Sciences, Karl-Franzens University, Graz, Austria aut NATIONALLICENCE 700 1- Hoinkes G. Department of Mineralogy and Petrology, Institute of Earth Sciences, Karl-Franzens University, Graz, Austria aut NATIONALLICENCE 773 0- Mineralogy and Petrology Springer-Verlag 88/1-2(2006-09-01), 341-362 0930-0708 88:1-2<341 2006 88 710 Metadata rights reserved Springer special CC-BY-NC licence nationallicence BK010053 XK010053 XK010000 NATIONALLICENCE NATIONALLICENCE NL-springer