Island-arc geochemical signatures of Cenozoic alkali-rich intrusive rocks from western Yunnan and their implication

Alkali-rich intrusive rocks in western Yunnan were derived from an enriched lithospheric mantle （ EM Ⅱ ） source. The data available indicated they are alkali-rich （ K2o ＋ Na2o 〉 8wt% ） and shoshonitic. Although formed in a within-plate environment they exhibit signatures of arc magmatic rocks, such...

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Bibliographic Details
Published in:Acta geochimica 2005, Vol.24 (4), p.361-369
Main Authors: Wu, Kaixing, Hu, Ruizhong, Bi, Xianwu, Peng, Jiantang, Zhan, Xinzhi, Chen, Long
Format: Article
Language:English
Subjects:
Barium
Cenozoic
Chondrites
Contaminated sediments
Contamination
Geochemistry
Island arcs
Lithosphere
Magma
Mesozoic
Plate tectonics
Rock
Rocks
Sediment
Sediment pollution
Sedimentary geology
Sediments
Signatures
Subduction
Subduction (geology)
Tectonics
Trace elements
Zirconium
云南
地球化学
碱性岩
金沙江
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Summary:Alkali-rich intrusive rocks in western Yunnan were derived from an enriched lithospheric mantle （ EM Ⅱ ） source. The data available indicated they are alkali-rich （ K2o ＋ Na2o 〉 8wt% ） and shoshonitic. Although formed in a within-plate environment they exhibit signatures of arc magmatic rocks, such as high amounts of LILE and LREE relative to the HFSE and HREE, and thus high Ba/Nb, Ba/Zr, Sr/Y, La/Yb ratios as well as mimic chondrite-normalized REE and primitive mantle-normalized trace element patterns of subducted sediments, and they fall in the collision- or arc-related tectonic setting field on all discrimination diagrams. This might suggest the enrichment be related to the substantial extent of sediment contamination by the Mesozoic Tethyan subduction processes.
ISSN:1000-9426
2096-0956
1993-0364
2365-7499
DOI:10.1007/BF02873799