Post-collisional transition from an extensional volcano-sedimentary basin to a continental arc in the Alborz Ranges, N-Iran

Petrology and geochemistry of the Karaj Dam basement sill: Implications for geodynamic evolution of the Alborz magmatic belt

“…As a result, the trace element compositions of the KDBS shoshonitic rocks are related to decompression but are derived from a metasomatized source, and so are indistinguishable from those derived directly from shoshonitic magmatism in typical arcs (e.g., Verdel et al, 2011). Extension and resultant decompression melting during the Eocene occurred during a stage of slab rollback (Dewey, 1980;Kazmin et al, 1986;Hassanzadeh et al, 2004;Brunet et al, 2003;Verdel et al, 2011), and the Karaj Formation and coeval intrusions are considered to have developed and evolved in a back-arc environment (Allen et al, 2003a,b;Brunet et al, 2003;Vincent et al, 2005;Guest et al, 2006a,b;Ballato et al, 2010;Asiabanha and Foden, 2012). The ratio versus ratio trace element plots are the best possible tools to test this theory and to distinguish between arc and back-arc as the environment in which the KDBS formed (e.g., Pearce and Stern, 2006).…”

“…This long-lasting period of subduction was followed by the collision of Arabia and One of the most significant events in the magmatic history of Iran was a widespread magmatic flare-up that occurred mainly in the UDMA and the AMB during the Eocene-Oligocene (Berberian and King, 1981;Verdel et al, 2011;Asiabanha and Foden, 2012). This phase of magmatism is characterized by rocks with intermediate compositions from calc-alkaline to pottasic affinity, which occur in an arc/back-arc system or extensional arc environment (Berberian, 1983;Kazmin et al, 1986;Hassanzadeh et al, 2004;Allen et al, 2003a,b;McQuarrie et al, 2003;Vincent et al, 2005;Agard et al, 2011;Verdel et al, 2011;Allen et al, 2013).…”

“…Much of the information available about the tectonics and the Cenozoic magmatism of the AMB has been derived mainly from studies into this phase of magmatism, and various scenarios and interpretations have therefore been proposed (e.g., Stöcklin, 1968;Jung et al, 1976;Brousse et al, 1977;Berberian and King, 1981;Priestley et al, 1994;Dilek and Moores, 1999;Allen et al, 2003a,b;Davidson et al, 2004;Hassanzadeh et al, 2004;Vincent et al, 2005;Verdel et al, 2011;Asiabanha and Foden, 2012). Little information is available, however, about the dynamics of the subduction zone or zones, the characteristics of the subduction beneath the AMB, including orientation and dip, and the tectonomagmatic relation between the AMB and adjacent regions, (e.g.…”

Petrochemistry and tectonic setting of the Davarzan-Abbasabad Eocene Volcanic (DAEV) rocks, NE Iran

“…12). The petrogenesis of the volcanics was closely related to major events during the geodynamic evolution of northeast Iran (Shojaat et al 2003;Shabanian et al 2012;Alavi 1996;Asiabanha et al 2009Asiabanha and Foden 2012). The Eocene successions, mainly composed of volcanics, c La/Yb vs. Dy/Yb plot used to determine the degrees of partial melting of the DAEV source rocks (after Thirlwall et al 1996).…”

“…Undoubtedly, the middle Eocene volcanic rocks of the area were related to Neo-Tethyan subduction and post-Eocene magmatism of the region associated with collision and post-collision events during the Oligocene-Miocene times (Berberian and King 1981;Ghasemi and Talbot 2006;Ghasemi et al 2010;Shabanian et al 2012;Asiabanha et al 2009Asiabanha and Foden 2012).…”