The evolution of the Arabian lower crust and lithospheric mantle - geochemical constraints from southern Syrian mafic and ultramafic xenoliths

Journal article
(Original article)


Publication Details

Author(s): Krienitz MS, Haase K
Journal: Chemical Geology
Publisher: Elsevier
Publication year: 2011
Volume: 280
Pages range: 271-283
ISSN: 0009-2541
Language: English


Abstract


Geochemical compositions of lower crustal and lithospheric mantle xenoliths found in alkali basaltic lavas from the Harrat Ash Shamah volcanic field in southern Syria place constraints on the formation of the Arabian-Nubian Shield in northern Arabia. Compositions of lower crustal granulites are compatible with a cumulate formation from mafic melts and indicate that they are not genetically related to their host rocks. Instead, their depletion in Nb relative to other incompatible elements points to an origin in a Neoproterozoic subduction zone as recorded by an average depleted mantle Sm-Nd model age of 630. Ma.Lithospheric spinel peridotites typically represent relatively low degree (< 10%) partial melting residues of spinel lherzolite with primitive mantle compositions as indicated by major and trace element modelling of clinopyroxene and spinel. The primary compositions of the xenoliths were subsequently altered by metasomatic reactions with low degree silicate melts and possibly carbonatites. Because host lavas lack these signatures any recent reaction of the lherzolites with their host magma can be ruled out. Sm-Nd data of clinopyroxene from Arabian lithospheric mantle lherzolites yield an average age of 640. Ma suggesting that the lithosphere was not replaced since its formation and supporting a common origin of the Arabian lower crustal and lithospheric mantle sections.The new data along with published Arabian mantle xenolith compositions are consistent with a model in which the lithospheric precursor was depleted oceanic lithosphere that was overprinted by metasomatic processes related to subduction and arc accretion during the generation of the Arabian-Nubian Shield. The less refractory nature of the northern Arabian lithosphere as indicated by higher Al, Na and lower Si and Mg contents of clinopyroxenes compared to the more depleted nature of the south Arabian lithospheric mantle, and the comparable low extent of melt extraction suggest that the northern Arabian lithosphere formed in a continental arc system, whereas the lithosphere in the southern part of Arabia appears to be of oceanic arc origin. © 2010 Elsevier B.V.



FAU Authors / FAU Editors

Haase, Karsten Prof. Dr.
Lehrstuhl für Endogene Geodynamik


External institutions
Christian-Albrechts-Universität zu Kiel


How to cite

APA:
Krienitz, M.-S., & Haase, K. (2011). The evolution of the Arabian lower crust and lithospheric mantle - geochemical constraints from southern Syrian mafic and ultramafic xenoliths. Chemical Geology, 280, 271-283. https://dx.doi.org/10.1016/j.chemgeo.2010.11.015

MLA:
Krienitz, Marc-Sebastian, and Karsten Haase. "The evolution of the Arabian lower crust and lithospheric mantle - geochemical constraints from southern Syrian mafic and ultramafic xenoliths." Chemical Geology 280 (2011): 271-283.

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Last updated on 2018-11-12 at 20:50