GIG OpenIR  > 中科院广州地化所(-2008)  > 会议论文
Geochemistry of Mesozoic mafic volcanic rocks from the Yanshan belt in the northern margin of the North China Block: relations with post-collisional lithospheric extension
Guo F; Fan WM; Li XY; Li CW
Source PublicationMeeting on Mesozoic Sub-Continental Lithospheric Thinning Under Eastern Asia
2005-06-01
Conference Date2005-6-1
Conference PlaceBeijing, PEOPLES R CHINA
Indexed BySCI
Language英语
AbstractMajor element, trace element and Sr-Nd isotope data for three suites of mafic volcanic rocks that erupted at c. 180 Ma (Group 1), c. 163-140 Ma (Group 2) and 136-110 Ma (Group 3) in the Yanshan belt in the northern margin of the North China Block (NCB) are presented in this paper. All the rocks show significant enrichment in large ion lithophile elements and light REE (LREE) but depletion in Nb-Ta and Th-U, and moderately radiogenic Sr ( (87) Sr/(86) Sr(i) = 0.7052-0.7068) and unradiogenic Nd (epsilon(Nd)(t) = - 15.1 to -7.2) isotopic compositions. Sr-Nd isotopic modelling suggests an insignificant role of crustal contamination or assimilation fractional crystallization, and the geochemical variations in these rocks were mainly attributed to source heterogeneity and variable degrees of ferromagnesian, plagioclase and accessory mineral fractionation. The low Th/La (0.039-0.10) points to recycling of low-Th/La (e.g. Th/La <0.2) ancient crustal materials into the source region, probably related to the palaeo-Asian Ocean subduction. Compared with the late Mesozoic mafic rocks from the NCB interior, the Yanshan belt mafic lavas generally have higher Al2O3, TiO2, P2O5, LREE, high field strength elements, Sr and (87) Sr/ (86) Sr(i) but lower MgO and compatible elements. Major element extrapolation (MgO = 8% normalization) reveals that the Yanshan belt mafic volcanic rocks have higher Ti-8 and Fe-8, and lower Si-8 than those from the NCB interior, suggesting that they were probably derived from a relatively fertile mantle source, different from the Mesozoic chemically refractory lithospheric mantle beneath the NCB interior. Combining the geochemical features of the mafic rocks with Mesozoic deformation events in the northern NCB, we suggest that the three stages of mafic volcanism were caused by episodic lithospheric extension. The Group I rocks, which occur locally along major faults, were generated during a post-compressional extension related to the collision between the NCB and Mongolian Block; the Group 2 rocks formed as a result of post-collisional lithospheric extension related to the collision between the North China-Mongolian Block and the Siberian plate; and the Group 3 rocks were extruded in an extensional regime in response to lateral escape related to surrounding plate interactions.
Document Type会议论文
Identifierhttp://ir.gig.ac.cn/handle/344008/9434
Collection中科院广州地化所(-2008)_会议论文
Recommended Citation
GB/T 7714
Guo F,Fan WM,Li XY,et al. Geochemistry of Mesozoic mafic volcanic rocks from the Yanshan belt in the northern margin of the North China Block: relations with post-collisional lithospheric extension[C],2005.
Files in This Item:
There are no files associated with this item.
Related Services
Recommend this item
Bookmark
Usage statistics
Export to Endnote
Google Scholar
Similar articles in Google Scholar
[Guo F]'s Articles
[Fan WM]'s Articles
[Li XY]'s Articles
Baidu academic
Similar articles in Baidu academic
[Guo F]'s Articles
[Fan WM]'s Articles
[Li XY]'s Articles
Bing Scholar
Similar articles in Bing Scholar
[Guo F]'s Articles
[Fan WM]'s Articles
[Li XY]'s Articles
Terms of Use
No data!
Social Bookmark/Share
All comments (0)
No comment.
 

Items in the repository are protected by copyright, with all rights reserved, unless otherwise indicated.