Petrogenesis of the Early Paleozoic Guixi leucogranite in central Jiangxi Province:Constraints from whole-rock geochemistry
In this study,we present the results of zircon U-Pb dating and whole-rock geochemical analysis of the Guixi granite in central Jiangxi Province.We discuss its genetic type,source characteristics,melting mechanism,and geodynamic background.The Guixi granite is classified as muscovite granite,with a zircon U-Pb age of 438±5 Ma.The results of whole-rock major and trace element analysis show that the Guixi granite is characterized by high silica,high potassium,low magnesium,low calcium,and strong peraluminous features.The LREE/HREE ratio of the Guixi granite ranges from 7.35 to 10.4,and their(La/Yb)N ranges from 8.08 to 15.0,indicating enrichment of light rare earth elements,depletion of heavy rare earth elements,and significant fractionation between light and heavy rare earth elements.The granite is relatively enriched in Rb,Th,U and K,while depleted in Sr,Ba,Ta,Nb.The relatively high Nb/Ta,Zr/Hf,K/Rb and Eu/Eu*ratios,as well as the low TE1,3 values,suggest that the Guixi granite is not a highly fractionated granite.The low Zr+Nb+Ce+Y(＜200×10-6)contents and Ga/Al ratios(＜2.5),high A/CNK ratios(＞1.2),the presence of aluminum-rich mineral muscovite,and the absence of mafic dark minerals indicate that the Guixi granite belongs to the S-type granite in terms of genetic type.The enriched whole-rock Nd isotope composition(εNd(t)=-11),high Rb/Sr ratio(＞2),moderate light rare earth element saturation temperatures and zircon saturation temperatures(699℃～794℃),and low titanium contents(＜0.2%)suggest that the Guixi granite was derived from ancient metasedimentary rocks and formed through muscovite dehydration melting.The Guixi granite was formed in a collisional environment rather than a subduction environment,indicating an intracontinental orogeny in the Early Paleozoic of South China.
国家科技期刊平台
NSTL
万方数据
