Deciphering the shoshonitic monzonites with I-type characteristic, the   Sisdagi pluton, NE Turkey: Magmatic response to continental lithospheric   thinning

doi:10.1016/j.jseaes.2012.02.003

CORC > 北京大学 > 地球与空间科学学院

	Deciphering the shoshonitic monzonites with I-type characteristic, the Sisdagi pluton, NE Turkey: Magmatic response to continental lithospheric thinning
	Karsli, Orhan ; Dokuz, Abdurrahman ; Uysal, Ibrahim ; Ketenci, Murat ; Chen, Bin ; Kandemir, Raif
刊名	journal of asian earth sciences
	2012
关键词	Mantle melting Lithospheric thinning Asthenospheric upwelling Shoshonitic I-type Sisdagi pluton Eastern Pontides PB ISOTOPIC CHARACTERISTICS OCEAN MANTLE DOMAIN NORTH CHINA CRATON BLACK-SEA REGION A-TYPE GRANITES EASTERN PONTIDES OROGENIC BELT GEOCHEMICAL CHARACTERISTICS NEOTETHYAN CONVERGENCE TECTONIC DEVELOPMENT
DOI	10.1016/j.jseaes.2012.02.003
英文摘要	Large-scale late Mesozoic to early Cenozoic plutons in the Eastern Pontide orogenic belt mostly show calc-alkaline and I-type geochemical features. However, we identify the Sisdagi pluton that has shoshonitic affinity and I-type character in the region. The pluton was emplaced at shallow depths (<5 km), revealed by Al-in hornblende barometry, in the northern margin of the orogenic belt, with SHRIMP zircon U-Pb age of 41.55 +/- 0.31 Ma, interpreted as dating magma crystallization. It is composed of monzonite, monzodiorite and monzogabbro. The samples show low zircon saturation temperature (T-zr) ranging from 603 to 769 degrees C compared to A-type rocks. They exhibit SiO2 contents of 47.6-61.4 wt.%, and high K2O + Na2O (5.0-8.8 wt.%) and K2O/Na2O (0.8-1.8). All the samples are characterized by low Mg# (<47) and relatively high but variable Al2O3 content (16.9-22.2 wt.%). They are also enriched in light rare earth elements (LREE), large ion lithophile elements (LILE) and depleted in high field strength elements (HFSE), with a weak negative Eu anomaly (Eu/Eu-center dot = 0.58-1.26) in mantle-normalized trace element patterns. The samples possess homogeneous initial Sr and Nd isotopic compositions, marked with low I-Sr = 0.70376-0.70408 and epsilon(Nd) (42 Ma) = +1.3 to +2.4. T-DM ages of the samples range from 0.70 to 0.85 Ga. The Pb isotopic ratios are (Pb-206/Pb-204) = 18.64-18.72, (Pb-207/Pb-204) = 15.51-15.58 and (Pb-208/Pb-204) = 38.31-38.65. These geochemical features imply that the parental magma resulted from melting of chemically enriched lithospheric mantle source. In such a case, a hot upwelling asthenosphere is necessary to partially melt the lithospheric mantle in order to form the parental magma. The pluton is considered to be a post-orogenic intrusion that was emplaced in an environment of lithospheric extension, triggering asthenospheric upwelling. The thermal anomaly induced by asthenospheric upwelling resulted in partial fusion of chemically enriched subcontinental lithospheric mantle beneath the region. Then, the shoshonitic melt, which subsequently underwent fractional crystallization with minor crustal contamination, ascent to shallower crustal levels to generate a monzonitic rock series ranging from monzogabbro to monzonite. All these data combined with the regional geology suggest that the crustal thickening as a consequence of regional compression during the Paleocene changed into a lithospheric extension and thinning throughout the early Cenozoic (at similar to 42 Ma) in the Eastern Pontides. Hence, the middle Eocene shoshonitic I-type magmatism is a unique pluton, signifying initiation of lithospheric thinning and thus of hot asthenospheric upwelling in the region. These interpretations also argue against the presence of an early Cenozoic subduction of oceanic slab in the Eastern Pontides. (C) 2012 Elsevier Ltd. All rights reserved.; Geosciences, Multidisciplinary; SCI(E); 0; ARTICLE; 45-62; 51
语种	英语
内容类型	期刊论文
源URL	[http://ir.pku.edu.cn/handle/20.500.11897/233371]
专题	地球与空间科学学院
推荐引用方式 GB/T 7714	Karsli, Orhan,Dokuz, Abdurrahman,Uysal, Ibrahim,et al. Deciphering the shoshonitic monzonites with I-type characteristic, the Sisdagi pluton, NE Turkey: Magmatic response to continental lithospheric thinning[J]. journal of asian earth sciences,2012.
APA	Karsli, Orhan,Dokuz, Abdurrahman,Uysal, Ibrahim,Ketenci, Murat,Chen, Bin,&Kandemir, Raif.(2012).Deciphering the shoshonitic monzonites with I-type characteristic, the Sisdagi pluton, NE Turkey: Magmatic response to continental lithospheric thinning.journal of asian earth sciences.
MLA	Karsli, Orhan,et al."Deciphering the shoshonitic monzonites with I-type characteristic, the Sisdagi pluton, NE Turkey: Magmatic response to continental lithospheric thinning".journal of asian earth sciences (2012).