期刊论文详细信息
Journal of earth system science | |
Pb isotope geochemistry of the late MioceneâPliocene volcanic rocks from Todeshk, the central part of the UrumiehâDokhtar magmatic arc, Iran: Evidence of an enriched mantle source | |
Mahnaz Khodami^11  | |
[1]Department of Geology, Yazd University, Yazd, Iran.^1 | |
关键词: Pb isotopes geochemistry; calc-alkaline; enriched mantle; UrumiehâDokhtar magmatic arc; Zagros orogen; Iran; | |
DOI : | |
学科分类:天文学(综合) | |
来源: Indian Academy of Sciences | |
【 摘 要 】
The late MioceneâPliocene volcanic rocks from Todeshk, south-east of Isfahan, are located in the middle of the UrumiehâDokhtar magmatic belt. The belt is considered the subduction-related magmatic arc. The late MioceneâPliocene calc-alkaline volcanic rocks are mainly andesite and dacite. The rocks have been formed during the post-collisional stage of the Zagros orogen. Geochemical data show the enrichment of light rare-earth elements and large ion lithophile elements such as Cs, Rb, K, Pb, Ba and Th as well as the depletion of elements with high field strength such as Nb, Ta and Ti. The PbâSrâNd isotopic ratios of the studied rocks are characterised by $^{206}$Pb/$^{204}$Pb =18.41â18.72; $^{207}$Pb/$^{204}$Pb =15.64â15.67; $^{208}$Pb/$^{204}$Pb = 38.49â38.83; $^{207}$Pb/$^{206}$Pb = 0.8372â0.8496; $^{208}$Pb/$^{206}$Pb = 2.0743â2.0905; $^{87}$Sr/$^{86}$Sr = 0.7051â0.7068 and $^{143}$Nd/$^{144}$Nd = 0.5125. The rocks have $\Delta$7/4Pb = 15.44â15.82 and $\Delta$8/4Pb = 57.26â60.44. Based on petrological studies and the whole rock Pb, Sr and Nd isotopes data, the late MioceneâPliocene calc-alkaline volcanic rocks have been generated from the partial melting of the subduction-related metasomatised mantle. Additionally, the slab-derived melts and fluids were recycled into the mantle source. The data demonstrate that terrigenous sediments accompanied by a subducted slab play an important role in the formation of the enriched mantle as the source of volcanic rocks.【 授权许可】
CC BY
【 预 览 】
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