Alaskan-type mafic-ultramafic complex at Padhar, Betul Belt, Central India

Abstract

We report here an Alaskan-type mafic-ultramafic complex at Padhar from the Precambrian Betul Belt of Central India. The Padhar intrusive bodies show lithological zoning defined by olivine-bearing ultramafic rocks in the core and gabbroic rocks at the margins, and are commonly accompanied by Cr-Cu-Ni sulphide mineralization. Mineral chemistry and whole-rock geochemistry of these rocks indicate that they are derived from the crystallization of hydrous magmas. The Padhar complex is characterized by high Mg and low abundance of incompatible trace elements. Flat REE pattern with negative Nb anomaly suggests arcmagmatism typical of Ural-Alaskan type. Presence of Mg-rich clinopyroxene and hornblende-rich rock types in the Padhar mafic-ultramafic intrusives along with paucity of orthopyroxenes in them further distinguish its from different types of complexes, i.e. ophiolite, Alpine and stratiform layered-type. These features are akin to Alaskan-type rocks as seen in Alaska, Canada and Urals of Russia. This finding of Alaskan-type ultramafic complex in the Padhar area of Betul Belt, Madhya Pradesh, is significant and has important implications in the tectonics and geodynamics of the Central Indian Tectonic Zone in general, and in the search of platinum group of minerals in particular.