Geochemistry,strontium isotopes characteristics and genesis of tremolite jade deposit in Dahua,Guangxi
Turbidite jade deposit in Dahua,Guangxi,produced in the poor magnesium carbonate rock stratum,is a new type of turbidite jade deposit.The source of its mineralization material and the cause of the study is rel-atively weak.This study has carried out a comparative study by testing the main trace elements and strontium i-sotopes of peripheral rocks,altered rocks,intrusive rocks and tremolite jade in the deposits.The results show that the trace element and rare earth element partitioning patterns tremolite jade are similar to those of limestone and marble,the trace element and rare earth element contents correlate well with marble(correlation coefficient 0.931),suggesting that the source of Ca is related to marble.There is a linear negative correlation between 87 Sr/86 Sr and 1 000/Sr in Dahua stratified tremolite jade,indicating that 87Sr/86Sr(0.707 0)is controlled by marble(0.707 5)and diabase(0.706 1)endmembers.The 87Sr/86Sr value obtained by extrapolating 1 000/Sr=0 is consistent with the 87 Sr/86 Sr value in the gabbro,suggesting that the mineralising fluid is magmatic hydro-thermal;the values of Y/Ho in Dahua stratified tremolite jade(avg.,49.10)are higher than those in marble and diabase(avg.,44.53 and 24.30,respectively),indicating that the marble is more strongly affected by magmatic-hydrothermal action.Combined with the characteristics of Dahua tremolite jade,it is inferred that Ca comes from marble,Mg and Si come from diabase.Using rare earth element composition,δCe,δEu,Zr/Hf,Nb/Ta,Sr/Ba,U/Th,W,V,Cu and other indicators,it determines that their mineralization environment is alkaline with high oxygen fugacity.The formation of tremolite jade deposits in Dahua,Guangxi,is divided into four stages:basic magmatic intrusion → limestone metamorphism to marble → formation of Mg-and Si-rich ba-saltic magmatic hydrothermal fluids→ hydrothermal fluid accounted for the formation of tremolite jade from mar-ble.
tremolite jadegeochemistrystrontium isotopeore-forming material sourceDahuaGuangxi
万方数据
维普
