Petrogenesis of mafic collision zone magmatism: the Armenian sector of the Turkish-Iranian Plateau
Neill, I.; Meliksetian, K.; Allen, M.B.; Navasardyan, G.; Kuiper, K.
Professor Mark Allen email@example.com
Head of Department
The Turkish–Iranian Plateau grew after the Middle Miocene following the initial Paleogene Arabia–Eurasia collision. Authors attribute uplift to break-off of the southern Neo-Tethys slab beneath the Bitlis–Zagros Suture at ~ 15–10 Ma, coupled with continued plate convergence and regional crustal shortening. Since this time there has been an upsurge in mantle-derived collision magmatism over large parts of NW Iran, Eastern Anatolia and the Lesser Caucasus, potentially hundreds of kilometres from the site of southern Neo-Tethys slab break-off, > 10 Myr after the proposed break-off event. Whole rock elemental and Sr–Nd–Pb–Hf isotope data are presented for < 3 Ma trachy-basalt to trachy-basaltic andesite lavas erupted in Armenia in the South Caucasus. Samples formed by < 5% melting of fertile subduction-modified spinel-facies lithospheric mantle, and few display elemental or isotopic evidence for contamination by the 45-km thick Mesozoic–Paleogene arc crust or South Armenian Block continental crust. Recent magmatic activity in Armenia may not be a direct consequence of southern Neo-Tethys slab break-off 300–450 km away, beneath the Bitlis Suture. Late Miocene break-off of a second (northern Neo-Tethys) slab beneath the Pontide Arc may have allowed asthenospheric upwelling over a wider area than was affected by southern Neo-Tethyan break-off. However, whole-scale delamination of mantle lithosphere is ruled out due to the modest degrees of partial melting, a lack of asthenospheric components and limited crustal involvement in magmatism. Small-scale sub-lithospheric convection may be complementary to break-off, causing localised removal of lithospheric mantle and aiding the occurrence of melting for a significant time interval after the break-off event(s). Collision magmas such as those in Armenia represent mantle-derived additions to continental crust, enriched in incompatible elements but with Th/La ratios ≤ 0.2, much lower than those calculated for continental crust (0.25–0.3). Collision magmatism in Turkic-style orogens must be balanced by infra-crustal recycling and delamination to produce bulk continental crust.
Neill, I., Meliksetian, K., Allen, M., Navasardyan, G., & Kuiper, K. (2015). Petrogenesis of mafic collision zone magmatism: the Armenian sector of the Turkish-Iranian Plateau. Chemical Geology, 403, 24-41. https://doi.org/10.1016/j.chemgeo.2015.03.013
|Journal Article Type||Article|
|Acceptance Date||Mar 12, 2015|
|Publication Date||May 1, 2015|
|Deposit Date||Mar 13, 2015|
|Publicly Available Date||Apr 2, 2015|
|Peer Reviewed||Peer Reviewed|
|Keywords||Arabia–Eurasia collision, Armenia, Continental crust, Orogenic plateau, Radiogenic isotopes, Sub-lithospheric convection|
Published Journal Article
Publisher Licence URL
© 2015 The Authors. This is an open access article under the CC BY license (http://creativecommons.org/licenses/by/4.0/).