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δ 11 B as tracer of slab dehydration and mantle evolution in Western Anatolia Cenozoic Magmatism
Author(s) -
Tonarini Sonia,
Agostini Samuele,
Innocenti Fabrizio,
Manetti Piero
Publication year - 2005
Publication title -
terra nova
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.353
H-Index - 89
eISSN - 1365-3121
pISSN - 0954-4879
DOI - 10.1111/j.1365-3121.2005.00610.x
Subject(s) - geology , asthenosphere , intraplate earthquake , mantle (geology) , geochemistry , subduction , cenozoic , magmatism , paleontology , tectonics , structural basin
Boron isotope data are presented for Cenozoic Western Anatolia rocks, which define two main associations: (i) calc‐alkaline, shoshonitic and ultra‐potassic rocks (Early to Middle Miocene); and (ii) Late Miocene–Quaternary intraplate alkali basalts. Boron data, together with Sr–Nd isotope and other trace elements, are consistent with a progressive dehydration of the slab, producing fluid phases gradually depleted in B (and 11 B). These fluids were added to the supraslab mantle, triggering a partial melting that gave rise to orogenic magmatism. The stretching and tearing of the slab caused by the faster convergence of Greece over Africa with respect to Anatolia facilitated an interaction of the upwelling subslab asthenosphere with residual slab‐fluids during the Late Miocene followed by production of typical intraplate magmas during the Pleistocene–Holocene, whose relatively high δ 11 B (approximately −2‰) is considered representative of the local asthenosphere not affected by subduction contamination.