Nb-depleted, continental rift-related Akaz metavolcanic rocks (West Kunlun): implication for the rifting of the Tarim Craton from Gondwana

GIG OpenIR > 中科院广州地化所(-2008)

	Nb-depleted, continental rift-related Akaz metavolcanic rocks (West Kunlun): implication for the rifting of the Tarim Craton from Gondwana
	Yuan C; Sun M; Yang JS; Zhou H; Zhou MF
Source Publication	Workshop on Tectonic Processes in the Evolution of China
	2002-04-01
Conference Date	2002-4-1
Conference Place	Hong Kong, PEOPLES R CHINA
Indexed By	SCI
Language	英语
Abstract	The Akaz metavolcanic rocks of the West Kunlun Mountains possess low to intermediate SiO2 (42.3-64.7 wt%) and MgO (2.69-7.54 wt%) and high TiO2 (0.94-3.05 wt%) and Fe2O3T (7.64-18.47 wt%), indicating a basaltic to andesitic protolith. These rocks have high contents of Zr (89.6-470 ppm), Nb (10.0-40.3 ppm), Y (19.7-52.7 ppm), Th (0.86-15.96 ppm) and total REE (67.7-407 ppm), and are characterized by relatively high Ti/Y (183-649), Th/Yb (0.5-3.9), and low Hf/Ta (3.0-8.6) ratios. They are LREE-enriched (La/Yb = 5.4-20) and most have small negative Nb anomalies (Nb/Nb* = 0.20-1.16). These characteristics are transitional between within-plate and subduction-related basalts. The relatively high Gd/Yb ratios (1.4-2.9) distinguish these rocks from island-arc tholeiites and the high Zr/Y (3-12), Ta/Yb (0.3-0.7) and low Zr/Nb (< 12) ratios strongly support a continental affinity. The protoliths for the Akaz metavolcanic rocks are interpreted to be continental rift basalts formed during rifting of the Tarim Craton from Gondwana. Stratigraphic and palaeontological data indicate that the rifting occurred in Sinian to Cambrian times, roughly contemporaneously with rifting in the East Kunlun and North Qilian orogenic belts farther to the east.
Document Type	会议论文
Identifier	http://ir.gig.ac.cn/handle/344008/9444
Collection	中科院广州地化所(-2008)
Recommended Citation GB/T 7714	Yuan C,Sun M,Yang JS,et al. Nb-depleted, continental rift-related Akaz metavolcanic rocks (West Kunlun): implication for the rifting of the Tarim Craton from Gondwana[C],2002.

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