Alireza Shaker Ardakani; Mohsen Arvin; Roland Oberhänsli
Volume 1, Issue 3 , December 2010, , Pages 47-64
Abstract
The Makran accretionary prism in southeastern Iran contains extensive Mesozoic melange zones and large intact ophiolites, representing remnants of the Neotethys oceanic crust that was ...
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The Makran accretionary prism in southeastern Iran contains extensive Mesozoic melange zones and large intact ophiolites, representing remnants of the Neotethys oceanic crust that was subducted beneath Eurasia. To the north of the Makran accretionary prism, the Jazmurian depression lies which is a subduction-related back-arc basin. The Ganj Complex is one of the ophiolitic complexes, located on the west side of the Makran accretionary prism and Jazmurian depression, and is bounded by the Jiroft fault system in the west. The Ganj Complex with an Upper Cretaceous age is composed mainly of lava flows, pillow lavas, acidic plutonic rocks and sedimentary rocks, which are intruded by northwest-southeast trending dykes and does not ressemble a classical ophiolitic sequence. It lacks the intrusive crustal and mantle sections. The Ganj Complex pillow lavas, mainly olivine basaltic, occur as normal and as mega-sized bodies and are mostly flattened - tubular in shape with bread crust crack surfaces. They show three textural zones from the top glassy (zone 1) through the intermediate (zone 2) to the holocrystaline interior (zone 3), with each characterized by varying assemblages of plagioclase and olivine that form different textures. The Ganj pillow basalts are characterized by variolitic, porphyritic, microlitic-porphyritic, intersertal, intergranular and amigdaloidal textures. Mineralogically, they consist of plagioclase ± olivine ± pyroxene + opaque. The outer glassy surfaces of pillows frequently consist of one, or rarely multiple rind. The rinds consist of three layers, which from surface inwards are: (1) sideromelane, (2) dark tachylyte and (3) tachylyte with elongated vesicles.
