Geochemical characteristics of lamprophyres in the Xikuangshan antimony ore deposits, Hunan province.

Element and isotope geochemistry of the lamprophyres veins in the Xikuangsh an antimony ore deposits is systematically researched in this article, aimi ng at discussing genesis of lamprophyres. The lamprophyres studied were for med ca 120Ma ago, prior to mineralization chronology, and is considered to be closely related to antimony mineralization in the Xikuangshan area. The MORB-normalized spidergrams of samples studied are rich in high field eleme nt, with depleted Nb-Ta and non-depleted Ti, strong enrichment in Th and we ak enrichment in Ce, being similar to spidergrams of volcanic arc basalt. T heir tectonic setting probably is destructive plate boundaries of an inter continent. The rare-earth element of sample studied have characteristics of high total contents and non-distinct Eu anomalies. The chondrite-normalize d REE patterns are right-inclined. The isotopic contents of sample have hig h Sr-87/Sr-87 and low Nd-143/Nd-144. Combining element and isotope geochemi stry with geological history, the lamprophyres studied in the area result f rom partial melting of enriched REE and HSFE fluid related to subduction of metasomatic mantle, mixing with a little underlying granite and limestone compositions.