TY - JOUR
T1 - Shallow melting of MORB-like mantle under hot continental lithosphere, Central Anatolia
AU - Reid, Mary R.
AU - Schleiffarth, W. Kirk
AU - Cosca, Michael A.
AU - Delph, Jonathan R.
AU - Blichert-Toft, Janne
AU - Cooper, Kari M.
N1 - Funding Information:
The reviews of Maryjo Brounce, Aaron Pietruszka, and an anonymous reviewer helped us more clearly convey the key points and rigor of our interpretations, and make them more accessible to a general audience. This research is part of the Continental Dynamics-Central Anatolia Tectonics (CD-CAT) international and interdisciplinary research project, supported by NSF grant EAR-1109826 to M.R.R. The collective efforts of the CD-CAT group are gratefully acknowledged. In particular, the support of Gonca Gencalioglu-Kuscu (Mugla University) was instrumental to the success of this project. J.R.D. received support from the Wiess Postdoctoral Research Fellowship at Rice University. J.B.T. acknowledges support from the French Agence Nationale de la Recherche through grant ANR-10-BLANC-0603. Patrick Maloney (formerly of NAU) assisted with some of the early work in this investigation. Members of ENS Lyon and especially Philippe Telouk are thanked for ensuring that M.R.R. could obtain the isotopic data reported here. The data used are listed in the supporting information and the references. Any use of trade, product, or firm names is for descriptive purposes only and does not imply endorsement by the U.S. Government.
Publisher Copyright:
© 2017. American Geophysical Union. All Rights Reserved.
PY - 2017/5/1
Y1 - 2017/5/1
N2 - Widespread mafic volcanism, elevated crustal temperatures, and plateau-type topography in Central Anatolia, Turkey, could collectively be the result of lithospheric delamination, mantle upwelling, and tectonic escape. We use results from 40Ar/39Ar geochronology, basalt geochemistry, and a passive-source broadband seismic experiment obtained in a collaborative international effort (Continental Dynamics-Central Anatolia Tectonics) to investigate the upper mantle structure and evolution of melting conditions over an ∼2400 km2 area south and west of Hasan volcano. New 40Ar/39Ar dates for the basalts mostly cluster between 0.2 and 0.6 Ma, but some scoria cones are as old as 2.5 Ma. Basalts are dominantly Mg-rich (Mg# = 62–71), moderately alkaline (normative Ne < 5 wt %), and, based on major and trace element signatures, derived from a peridotitic source. Covariations between radiogenic isotope and trace element signatures reveal contributions from a subduction-related component and intraplate-like mantle asthenosphere, as well as from ambient upper mantle. Central Anatolian basalts reflect maximum mantle potential temperatures of <1350°C and an average pressure of melt equilibration of 1.4 GPa, which are cooler and shallower than for basalts from Eastern and Western Anatolia. When considered in light of regionally slow upper mantle shear wave velocities, the mantle lithosphere may be thin and infiltrated by melts, or largely absent. An absence of secular changes in melting conditions suggests little to no lithospheric thinning over the past ∼1 Ma, despite evidence for lithospheric extension. Hasan basalts appear to be generated by decompression melting in response to the rollback of the Cyprean slab.
AB - Widespread mafic volcanism, elevated crustal temperatures, and plateau-type topography in Central Anatolia, Turkey, could collectively be the result of lithospheric delamination, mantle upwelling, and tectonic escape. We use results from 40Ar/39Ar geochronology, basalt geochemistry, and a passive-source broadband seismic experiment obtained in a collaborative international effort (Continental Dynamics-Central Anatolia Tectonics) to investigate the upper mantle structure and evolution of melting conditions over an ∼2400 km2 area south and west of Hasan volcano. New 40Ar/39Ar dates for the basalts mostly cluster between 0.2 and 0.6 Ma, but some scoria cones are as old as 2.5 Ma. Basalts are dominantly Mg-rich (Mg# = 62–71), moderately alkaline (normative Ne < 5 wt %), and, based on major and trace element signatures, derived from a peridotitic source. Covariations between radiogenic isotope and trace element signatures reveal contributions from a subduction-related component and intraplate-like mantle asthenosphere, as well as from ambient upper mantle. Central Anatolian basalts reflect maximum mantle potential temperatures of <1350°C and an average pressure of melt equilibration of 1.4 GPa, which are cooler and shallower than for basalts from Eastern and Western Anatolia. When considered in light of regionally slow upper mantle shear wave velocities, the mantle lithosphere may be thin and infiltrated by melts, or largely absent. An absence of secular changes in melting conditions suggests little to no lithospheric thinning over the past ∼1 Ma, despite evidence for lithospheric extension. Hasan basalts appear to be generated by decompression melting in response to the rollback of the Cyprean slab.
KW - Ar/Ar basalt geochronology
KW - Central Anatolia
KW - magma genesis
KW - primary basalts
KW - shear wave tomography
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U2 - 10.1002/2016GC006772
DO - 10.1002/2016GC006772
M3 - Article
AN - SCOPUS:85019130188
SN - 1525-2027
VL - 18
SP - 1866
EP - 1888
JO - Geochemistry, Geophysics, Geosystems
JF - Geochemistry, Geophysics, Geosystems
IS - 5
ER -