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| Titel |
Metasomatic overprint of CO2-rich fluids/melts from altered oceanic crust and subducted Triassic plume-influenced volcanics via shallow oceanic subduction of Cyprus arc, and remobilization of EM-II type mantle metasomes beneath Isparta Angle, SW Turkey |
| VerfasserIn |
H. Çoban, N. Hoang, M. F. J. Flower, O. Parlak, Ş. Caran, L. Dallai, Ö. Çakir, M. Erduran |
| Konferenz |
EGU General Assembly 2012
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| Medientyp |
Artikel
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| Sprache |
Englisch
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| Digitales Dokument |
PDF |
| Erschienen |
In: GRA - Volume 14 (2012) |
| Datensatznummer |
250059296
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| Zusammenfassung |
| Episodic extensional basins of Isparta Angle (SW Turkey) host similar post-collisional mafic
(Si-poor and Si-rich) potassic rock types (e.g., lamproite, leucite-basalt, lamprophyre,
absarokite, shoshonite) with contrasting geochemical signatures within the distinct
geographical locations (e.g. orogenic-types at north, transitional-types at centre and
anorogenic-types at centre and south) in a back-arc position. Such contrasting magmas
producing these rock series can be evaluated into two groups from north to south: i) older
(Early-Late Miocene) orogenic (Si-rich and Si-poor) mafic potassic magmas in the northern
Kirka, Afyon, Sandikli extensional basins, and ii) younger (Late Miocene-Plio-Quaternary)
transitional to anorogenic (Si-poor) mafic potassic magmas in the central Isparta and southern
Bucak extensional basins. Accordingly, relative to the wide variation of 87-86Sr isotopic
compositions in northern orogenic magmas, Nd-Pb isotopic variations reflect a gradual
decrease in 207-208Pb with an increasing 206Pb and 143-144Nd ratios from north to south,
relatively. Similarly, in contrast to the those of young transitional to anorogenic magmas with
FOZO-like mantle signature, geochemical and isotopic variations of older orogenic
magmas suggest a crust-contaminated, subduction-modified (metasomatised) EM-II
type mantle source, interacting with asthenosphere. It is inferred that carbonate
wall-rock assimilation for orogenic Si-poor potassic magmas and carbonate-free
wall-rock assimilation for orogenic Si-rich potassic magmas played a significant role
during their evolution, as well as source contamination. The striking geochemical
and isotopic variations of overlapping post-collisional older orogenic and younger
transitional to anorogenic potassic magmas also reflect the geochemical imprints
of distinct metasomatic agents in mantle metasomes beneath northern orogenic,
central transitional and southern anorogenic volcanic centres. We propose that the
metasomatic enrichment mechanism of the mantle metasomes beneath the southern
transitional to anorogenic volcanic centres can be explained by the remobilization
and overprinting of CO2-rich FOZO-like metasomatic melts/fluids, released by
partial melting of altered oceanic crust and subducted Triassic plume-influenced
materials (e.g., Triassic-Early Cretaceous alkali basalts with HIMU signature), into
the pre-existing EM-II type orogenic mantle metasomes during shallow oceanic
subduction of Cyprus arc (between Late Miocene and Plio-Quaternary). Remelting
of this remobilized mantle metasomes (producing ultrapotassic melts), followed
by mixing with asthenospheric magmas, have produced transitional-anorogenic
potassic magmas with FOZO-like mantle signature, under an extensional tectonic. |
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