Document Type : Original Research Paper
Authors
1 M. Sc. Student, Department of Geology, Faculty of Science, University of Sistan and Baluchestan, Zahedan, Iran
2 Assistant Professor, Department of Geology, Faculty of Science, University of Sistan and Baluchestan, Zahedan, Iran
Abstract
The Deh-Salm metamorphic complex (DMC), late Jurassic in age, is exposed at the west of Nehbandan and at the the eastern margin of the Lut block. This is one of the exceptional outcrops of the Lut block’s basement in East Iran. The metamorphosed ultramafic rocks in this complex are identified and introduced for the first time, and are studied in association with the metabasites. Extensive field excursions as well as satellite image investigations represented the metabasites and metaperidotites of the DMC in three elongated and separate belts, parallel to the extension of the complex; we named the belts as the east, central, and the west belts. A tectonic, broken to dismembered units of greenschist, amphibolite, metaperidotite, serpentinite, and talc-schist can be recognized in the east and central belts, while, amphibole-calcschist is the most important rock constituent of the west belt in the Galugah complex. The main minerals in the rocks of these belts are hornblende, epidote, plagioclase (andesine), and sporadic pyroxene in the metabasite, and olivine, ortho-amphibole, augite, talc, and spinel in metaperidotite, respectively. On the basis of the geochemical studies, the protoliths of the mentioned rocks are classified in the basalt and peridotite groups. However, due to metamorphic and intense metasomatic processes, it is impossible to suggest a distinct origin and tectonic setting for the above metamorphic assemblages. The presence of mafic and ultramafic metamorphic rocks adjacent to the other rock units of the DMC indicates that the mafic-ultramafic rocks were initially emplaced in the eastern margin of the Lut block in a time before the late Jurassic, then they were metamorphosed in their recent arrangement.
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