Structural interpretation of new high-resolution aeromagnetic and radiometric data over central Iran: Block definition and rotational tectonics

Abstract

New high-resolution geophysical data over Central Iran defines > 30 continental fragments or blocks and lithotectonic domains, which are bounded by large-scale,kinematically-coherent structures that may be traced under significant cover. Normal, inverted normal and basin-bounding faults, and thrusts were transposed tosteeper dips with subsequent strike-slip movement. Assembly required three triangular“keystone blocks”, with edges defined by entrained ophiolites, which arerequired by rotational tectonics and the assembly of at least three adjacent blocks, in this instance combined with anticlockwise rotation of the Lut Block and CentralIranian Microcontinent. Late-kinematic, brittle-ductile to brittle, NNE-to NE-trending structures are superimposed on the macrostructural pattern. Fromc.12 Maonwards, NW-directed compressional tectonics resulted in the development of NNW-trending, dextral, strike-slip structures, notably the Dehshir Fault, whichoverlapped temporally with the main Cu-bearing, porphyry-forming event and Urumieh-Dokhtar Magmatic Arc development. The Shir-Kuh Block and fragmentsimmediately to the north of it originated approximately 200 km to the north, at the SW edge of the Anarak Metamorphic Complex. Southward movement of the Shir-Kuh Block was due to a combination of dextral movement along the Dehshir Fault and anticlockwise rotation of the Lut and Tabas Blocks. Major faults are delineatedin four separate basins: the Shotori Basin, the Kharanaq Basin, the Farrokhi Basin and the Gonabad Basin.