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| Titel |
Contrasting melt equilibration conditions across Anatolia |
| VerfasserIn |
Mary Reid, Jonathan Delph, W. Kirk Schleiffarth, Michael Cosca |
| Konferenz |
EGU General Assembly 2017
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| Medientyp |
Artikel
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| Sprache |
en
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| Digitales Dokument |
PDF |
| Erschienen |
In: GRA - Volume 19 (2017) |
| Datensatznummer |
250152952
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| Publikation (Nr.) |
 EGU/EGU2017-17864.pdf |
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| Zusammenfassung |
| The 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 in response to Arabian-Anatolian plate collision. We
used the results from basalt geochemistry and a passive-source broadband seismic experiment
obtained as part of an international collaborative effort (Continental Dynamics – Central
Anatolia Tectonics) to investigate the crust-mantle structure and melting conditions
associated with the Quaternary Hasandag Monogenic Cluster (HMC) south and west of
Hasandag volcano. The HMC is unusually mafic, not only for Central Anatolia but globally,
enabling meaningful comparisons between geochemical and seismic interpretations of mantle
conditions.
HMC basalts are characterized by orogenic signatures that could have originated
(1) in mantle wedge that, after stagnating because of collision, was remobilized
south and upward as a result of rollback of the African slab or, alternatively (2) by
piecemeal foundering of residual mantle lithosphere into convecting upper mantle,
producing small-scale convection and associated decompression melting. Melt
equilibration conditions for the HMC are hot (TP ∼1335-1250˚ C, assuming 1-4 wt.%
H2O) and shallow (P = 1.1 to 1.6 GPa), approaching those for MORB. Shear wave
velocities are relatively constant at ∼4.1 km/s between the Moho and a depth of
∼45-50 km (∼1.4 GPa; Fig. 6), below which Vs increases with increasing depth. We
infer that a melt-perfused mantle lid could be locally present between 40 and 55
km.
In contrast to Central Anatolia, estimated equilibration conditions for Western Anatolia
and Eastern Anatolia (east of the Inner Tauride Suture) mantle melts are hotter (by ≥60˚ C)
and deeper (mostly by 0.6-1.0 GPa). They also have chemical signatures that, unlike Central
Anatolia, are similar to those of intraplate basalts. These differences are likely related to the
presence of a fragmenting, if quite deep, Cyprus slab beneath Central Anatolia, in contrast to
absence of the Arabian slab beneath Eastern Anatolia since at least 10 Ma, and flow
of deep-seated asthenosphere through a tear in the African plate under Western
Anatolia.
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