A P-T path for amphibolites from the metamorphic sole of the Dinaride ophiolite zone in Bosnia (CROSBI ID 648545)
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Podaci o odgovornosti
Balen, Dražen ; Massonne, Hans-Joachim
engleski
A P-T path for amphibolites from the metamorphic sole of the Dinaride ophiolite zone in Bosnia
The Dinarides, an Alpine-cycle mountain chain in SE Europe, originated along the margin of the Adriatic microplate. It is characterized by complex fold, thrust, and imbricate structures and partially dismembered ophiolites forming significant parts of the Dinarides. In the Krivaja-Konjuh ultramafic massif (KKUM ; Bosnia) tectonic peridotite (spinel lherzolite) occurs as NE deeping thrust sheets underlain by gradually decreasing high- to low-grade metamorphic sole rocks (up to 1200 m thick). The sole rocks originated from cumulus gabbro and peridotites and are mainly composed of granulite and amphibolite varieties with various proportions of amphibole, plagioclase, pyroxenes, garnet, and quartz. These rocks vary in textures (granoblastic, porphyroblastic and nematoblastic) and grain size. Conventional thermobarometry of garnet- and clinopyroxene-bearing amphibolites directly beneath the contact to the overlying peridotite resulted in peak pressure (P) – temperature (T) conditions of 11-12 kbar (depth of 35–40 km) and 745-830°C. Those amphibolites without clinopyroxene experienced peak conditions of 7 kbar and 630°C, whereas the lowermost-grade amphibolites yielded peak temperatures of 550°C only. The obtained values can be related to a geothermal gradient of 21-25 °C/km. P-T pseudosections, contoured by mineral isopleths, combined with chemical zonation of garnet, elucidated by X-ray mapping, and the study of the succession of accessory Ti-minerals (Ilmenite->Rutile->Titanite) suggest a composite P-T path characterized by pressure decrease accompanied by temperature increase. This path can be interpreted in the frame of late Jurassic to early Cretaceous regional geodynamic processes that involve collision at the edge of the Adriatic microplate, subduction and underplating of mafic cumulus rocks under the hot upper mantle part of the KKUM and finally subsequent erosional events. Support by the Croatian Science Foundation (IP-2014-09-9541) is acknowledged.
P-T path, amphibolite, metamorphic sole, Dinarides
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Podaci o prilogu
V33D-3145-x.
2016.
objavljeno
Podaci o matičnoj publikaciji
2016 AGU Fall Meeting
Podaci o skupu
2016 AGU Fall Meeting
poster
12.12.2016-16.12.2016
San Francisco (CA), Sjedinjene Američke Države