滇西富碱斑岩中特殊包体岩石的流体包裹体幔源不混溶特征

滇西地区沿金沙江-哀牢山断裂带产出了一套新生代富碱斑岩,其中发现了与镁铁-超镁铁质深源包体岩石共生的含石英的方解石包晶(体)、石英钠长石伟晶岩包体和含玻璃包裹体的纯石英包晶(体)以及富铁熔浆包体.流体包裹体地球化学研究表明,该四类特殊包体的形成与富含CO2流体持续减压而造成的不混溶作用有关;而玻璃包裹体与水溶液包裹体以...

Immiscible characteristics of mantle-derived fluid inclusions in special xenoliths from Cenozoic alkalic-rich porphyry in west Yunnan

There are a series of Cenozoic alkali-rich porphyries along Jinshajiang-Ailaoshan fault belt in western Yunnan Province.Quartz calcite peritectic,quartz-albite pegmatitic xenolith,glass inclusions-bearing pure quartz peritectic and Fe-rich melt xenoliths have been discovered from alkali-rich porphyries.All of these are paragenesis with mafic-ultramafic deep xenoliths.Geochemistry of fluid inclusions show that formation of pure quartz peritectic,quartz calcite peritectic and pegmatitic xenolith of quartz-albite is related to immiscibility,which is caused by continuous decompressing of CO2-rich fluid.The paragenetic relationship,with paragenesis of glass H2O-NaCl and CO2 inclusions,indicates the immiscibility of melt and liquid fluid.REE and trace elements indicate that fluid came from enriched mantle.Reversed anomalies of Zr and Hf in pure quartz peritectic and iron-rich melt xenoliths shows special peritectic(xenoliths) are immiscible products of mantle fluid or melt,because of the decompression in upwelling,implying that mantle fluids might change from melt to liquid fluid.