Adakite-like granitoid porphyries in the Eastern Pontides, NE Turkey:   Potential parental melts and geodynamic implications

doi:10.1016/j.lithos.2011.08.014

CORC > 北京大学 > 地球与空间科学学院

	Adakite-like granitoid porphyries in the Eastern Pontides, NE Turkey: Potential parental melts and geodynamic implications
	Karsli, Orhan ; Ketenci, Murat ; Uysal, Ibrahim ; Dokuz, Abdurrahman ; Aydin, Faruk ; Chen, Bin ; Kandemir, Raif ; Wijbrans, Jan
刊名	lithos
	2011
关键词	Adakite-like porphyry Partial melting Heterogeneous lower continental crust Eastern Pontides NE Turkey LOWER CONTINENTAL-CRUST THICKENED LOWER CRUST TRONDHJEMITE-GRANODIORITE TTG PB ISOTOPIC CHARACTERISTICS UNDERPLATED BASALTIC CRUST OCEAN MANTLE DOMAIN SLAB-DERIVED MELTS I-TYPE GRANITOIDS BLACK-SEA REGION NORTHERN TURKEY
DOI	10.1016/j.lithos.2011.08.014
英文摘要	The tectonic setting of the Eastern Pontides during the late Mesozoic to early Cenozoic remains a subject of debate. Petrogenesis of adakite-like granitoid porphyries plays a critical role in determining the nature of the lower continental crust and mantle dynamics during orogenic processes in the region. Here we describe, for the first time, the late Paleocene to early Eocene adakite-like granitoid porphyries from the northern part of the Eastern Pontides although their counterparts in the southern part have recently been found. The adakitic porphyries, which emplaced into the subduction-related Turonian-Santonian volcanics from northern part of the region, consist of I-type calc-alkaline quartz monzonite-tonalite (SiO(2) = 62.89-65.07 wt.%) and high-k calc-alkaline granodiorite-granite associations (SiO(2) = 69.06-70.43 wt.%). The former displays peraluminous to metaluminous signatures, whereas the latter shows peraluminous geochemical character. The granite-granodiorite porphyries have high K(2)O (3.32-3.84 wt.%), and low Na(2)O (3.48-4.61 wt.%) and MgO (0.91-1.04 wt.%) relative to the quartz monzonite-tonalite association (K(2)O = 1.50-1.92 wt.%; Na(2)O = 4.08-6.45 wt.%; MgO = 1.44-2.07 wt.%). Ar-Ar geochronology studies on the amphibole separates reveal that the adakite-like porphyries have a crystallization ages of 51.34 +/- 0.27 to 53.55 +/- 0.34 Ma. Here, we contend that these rocks were formed by partial fusion of a mafic lower continental crust in a collisional phase but not in a subduction setting. All the samples exhibit the typical geochemical characteristics of adakite, that is, high Sr (250-1141 ppm), high Sr/Y ratios (16-147), low Y (6.8-14.8 ppm) and low HREE concentrations; they are similar to adakites formed by slab melting associated with the subduction zone. However, the rocks exhibit heterogeneity in isotopic composition, with I(Sr) ranging from 0.70554 to 0.70986, epsilon(Nd) (51 Ma) from -8.5 to -0.9 and Nd model ages from 0.72 to 1.26 Ga. The samples are characterized by relatively high Th, Th/U and no significant Eu anomalies, implying that garnet was stable in their source during partial melting. The compositional diversity between rock groups is probably related to partial melting of heterogeneous lower crustal source. All of the features are inconsistent with a slab-melting origin and slab-related petrogenetic model, but instead, they favor an origin by melting of heterogeneous lower continental crust due to a thermal anomaly that was induced by the upwelling of the asthenosphere through a slab break-off in a collisional setting. These interpretations argue against the evidence for the presence of an early Cenozoic arc setting in the Eastern Pontides. Instead, the early Cenozoic time in the region may be attributed to a geodynamic response to a post-collisional uplift phase that occurred along the continent-continent collision between the Pontide and the Anatolide-Tauride blocks. (C) 2011 Elsevier B.V. All rights reserved.; http://gateway.webofknowledge.com/gateway/Gateway.cgi?GWVersion=2&SrcApp=PARTNER_APP&SrcAuth=LinksAMR&KeyUT=WOS:000298070600023&DestLinkType=FullRecord&DestApp=ALL_WOS&UsrCustomerID=8e1609b174ce4e31116a60747a720701 ; Geochemistry & Geophysics; Mineralogy; SCI(E); 20; ARTICLE; 1-2; 354-372; 127
语种	英语
内容类型	期刊论文
源URL	[http://ir.pku.edu.cn/handle/20.500.11897/237708]
专题	地球与空间科学学院
推荐引用方式 GB/T 7714	Karsli, Orhan,Ketenci, Murat,Uysal, Ibrahim,et al. Adakite-like granitoid porphyries in the Eastern Pontides, NE Turkey: Potential parental melts and geodynamic implications[J]. lithos,2011.
APA	Karsli, Orhan.,Ketenci, Murat.,Uysal, Ibrahim.,Dokuz, Abdurrahman.,Aydin, Faruk.,...&Wijbrans, Jan.(2011).Adakite-like granitoid porphyries in the Eastern Pontides, NE Turkey: Potential parental melts and geodynamic implications.lithos.
MLA	Karsli, Orhan,et al."Adakite-like granitoid porphyries in the Eastern Pontides, NE Turkey: Potential parental melts and geodynamic implications".lithos (2011).