Geochemistry and petrogenesis of intrusive and extrusive ophiolitic plagiogranites, central Anatolian crystalline complex, Turkey

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doi: 10.1016/S0024-4937(97)00044-3
Authors:Floyd, P. A.; Yaliniz, M. K.; Goncuoglu, M. C.
Author Affiliations:Primary:
Keele University, Department of Earth Sciences, Staffordshire, United Kingdom
Other:
Celal Bayar University, Turkey
Middle East Technical University, Turkey
Volume Title:Lithos (Oslo)
Source:Lithos (Oslo), 42(3-4), p.225-240. Publisher: Elsevier, Amsterdam, International. ISSN: 0024-4937
Publication Date:1998
Note:In English. 53 refs.; illus., incl. 2 tables, geol. sketch maps
Summary:Plagiogranites associated with the Sarikaraman ophiolite of the Central Anatolian Crystalline Complex, Turkey, closely resemble other plagiogranites from supra-subduction zone-type ophiolites of Neotethys. The ophiolite is remarkable in displaying a higher proportion of the plagiogranite suite (ca. 10% by volume) than is usually associated with such bodies. The Sarikaraman plagiogranites are represented by intrusive sheets and netvein trondhjemites largely developed at the top of the upper gabbros and as multiphase dykes within the sheeted dyke complex. The plagiogranite dykes are considered to feed extrusive silicified rhyolites associated with the basaltic lavas in the volcanic section of the ophiolite. Field relations suggest that the trondhjemites were probably generated from the roof section of a dynamic and evolving gabbroic magma chamber. Both the deep-seated trondhjemites and the volcanic rhyolites constitute the Sarikaraman plagiogranite suite. Geochemically there is complete overlap between the intrusive trondhjemites and extrusive rhyolites, which are characterised by (MORB-normalized) low HFS element contents with small negative Nb-Ta anomalies and variably enhanced LIL element abundances. Unlike other plagiogranites, however, the Sarikaraman suite is not characterized by consistently low K2O contents; a feature that reflects the variable mobilization of the LIL elements under lower greenschist facies conditions. The REE are uniformly enriched relative to the basic components of the complex, but have similar normalized patterns exhibiting mild light REE depletion. In terms of their origin, the initial or most primitive plagiogranite melts could have been generated by either fractional crystallization (70-85% of clinopyroxene-feldspar±amphibole) or partial melting (5-15% batch melting) of a gabbroic "source material", although only the first process can produce most of the range of the plagiogranite compositions. As a group the plagiogranites exhibit some degree of internal variation which can be generated by further fractionation largely dominated by feldspar with minor apatite and amphibole. Abstract Copyright (1998) Elsevier, B.V.
Sections:Geochemistry
Subsections:Igneous rocks
Subjects:Chemical composition; Dikes; Diorites; Extrusive rocks; Fractional crystallization; Genesis; Geochemistry; High-field-strength elements; Igneous rocks; Intrusions; Lithofacies; Magmas; Metals; Ophiolite; Partial melting; Petrography; Plagiogranite; Plate tectonics; Plutonic rocks; Rare earths; Rhyolites; Subduction; Trondhjemite; Volcanic rocks; Asia; Middle East; Turkey; Anatolian crystalline complex; Large ion lithophile elements; Sarikaraman Ophiolite; Sarikaraman plagiogranites
Coordinates:N384500 N384500 E0341500 E0341500
Abstract Numbers:98M/3904
Record ID:1998031657
Copyright Information:GeoRef, Copyright 2019 American Geosciences Institute. Reference includes data from CAPCAS, Elsevier Scientific Publishers, Amsterdam, Netherlands
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