检索结果-南通市图书馆

shrimp Age and Geochemistry of the Bikou Volcanic Terrane:Implications for Neoproterozoic Tectonics on the Northern Margin of the Yangtze Craton

引用

Acta Geologica Sinica(English Edition) 2003年第4期77卷 479-490页

作者： YANQuanren WANGZongqi A.D.HANSON P.A.DRUSCHKE YANZhen LIUDunyi JIANPing SONGBiao WANGTao JIANGChunfa InstituteofGeology ChineseAcademyofGeologicalSciencesBeijing100037 DepartmentofGeosciences UniversityofNevadaLasVegasLasVegasNV89154-4010USA InstituteofGeologyandGeophysics ChineseAcademyofSciencesBeijing100029

The Bikou volcanic terrane is predominated by subalkaline tholeiitic lavas. Rock samples display lower initial ratios of Sr and Nd, 0.701248-0.704413 and 0.511080-0.512341 respectively. 207Pb and 208Pb are significantly enriched in the lavas. Most samples have positive εNd, which indicates that the magma was derived from EM-type mantle source, while a few samples with negative εNd indicate that there was contamination in the magma evolution. Magma differentiation is demonstrated by variations of LREE and LILE from depletion to enrichment. Additionally, normalized REE patterns and trace elements showed that lavas from the Bikou volcanic terrane have similar characteristics to those of basalts in arc settings caused by subduction and collision. Analyses showed that the Bikou volcanic terrane is a volcanic arc. New evidence proved that the Hengdan Group, north of the Bikou arc, is a turbidite terrane filling a forearc basin. Consequently, the Bikou volcanic terrane and the Hengdan turbidite terrane construct an arc-basin system. New shrimp ages showed that this arc-basin system developed on the northern margin of the Yangtze craton in the Neoproterozoic (846-776 Ma), and this arc-basin system is in agreement with the tectonic processes of Rodinia in the Neoproterzoic.

关键词： geochemistry Sr-Nd-Pb isotopes shrimp ages Bikou Volcanic Terrane southwestern Qinling Mts. Yangtze Craton Rodinia

来源：