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Mineral chemistry and thermobarometry of plutonic, metamorphic and anatectic rocks from the Tueyserkan area (Hamedan, Iran)

Sepahi A. A., Borzoei K., Salami S.

Geological Quarterly

2013

Vol. 57, No. 3

515–-526

The study area is a part of the NW to SE striking Sanandaj–Sirjan metamorphic belt in western Iran. The Alvand Pluton, consisting of rocks that range in composition from gabbro to granite, is the major magmatic rock complex of this area. Gabbroic rocks include olivine gabbro, gabbro norite, norite and gabbro. Rocks around the Alvand Pluton were subjected to different P–T conditions due to polymetamorphism. Common metamorphic rocks are meta-pelites, but some meta-psammites, meta-basites and meta-carbonates also occur. Slates, phyllites, schists, migmatites and hornfelses are major rock units of meta-pelites in the metamorphic sequence. Based on mineral chemistry, the highest temperature of crystallisation (1300°C) was determined for the olivine gabbros, and the lowest temperature (950°C) was calculated for the hornblende-bearing gabbros. Clinopyroxene–plagioclase barometry suggests that pressures near 5 to 6 kbars prevailed during the crystallisation of the various mafic rocks. P–T estimates yield maximum temperatures of 700–750°C at 5–6 kbars for the high-grade metamorphic rocks from the metamorphic aureole around the pluton. These results indicate that the heat released from the Alvand Pluton (T = 950–1300°C), which intruded the metamorphic rocks at middle and upper crustal levels, was sufficient to cause partial melting leading to formation of the metatexites, diatexites and restite-rich S-type granites. During this process, part of the deep-seated gabbro-dioritic rocks were transported to higher crustal levels by viscous, enclave- and crystal-rich granitic magmas of the partial melting zone.

Proterozoiczne zmiany retrogresywne zapisane w granulitach i gnejsach podlaskiego kompleksu metamorficznego

Krzemińska E.

Przegląd Geologiczny

2001

Vol. 49 nr 12

1129-1136

Praca prezentuje wyniki badań petrologicznych oraz dane termobarometryczne granulitów i gnejsów z trzech głębokich otworów wiertniczych z kompleksu podlaskiego, w polskiej części platformy wschodnioeuropejskiej. Zastosowane geotermobarometry rejestrują w granulitach z Mielnika warunki wczesnoretrogresywnego etapu metamorfizmu (T = 650-700oC; p = 5,8-6,2 kbar) oraz regresywnego (T = 520-550oC; p = 4,1-5,2 kbar) etapu metamorfizmu proterozoicznego, datowanego na co najmniej 1527 mln lat. Skonstruowano hipotetyczną ścieżkę p-T dla tego stadium metamorfizmu, porównując otrzymane wyniki z analogicznymi danymi z zachodniej części białorusko-bałtyckiego pasa granulitowego i zachodniolitewskiego masywu granulitowego (rejon Lazdijai).

This paper presents the results o)penological study and thermobarometric data of granulites and gneisses from deep boreholes, from the Podlasie Complex, in Polish part of the East European Craton. Applied geothermobarometers indicate an early-retrograde, near peak (T = 650-700" C, p = 5.8-6.2 kbar) and retrograde stage (T- 520-550°C, p = 4.1-5.2 kbar) of Proterozoic metamorphism (1527 Ma) in the Mielnik granulites. These metamorphic conditions were also compared with those from the Ivje block in the Belarus-Baltic Granulite Belt and Lazdijai area, Western-Lithuanian Granulkę Domain.