The Origin Of Volcanic Rocks From East Tianshan And Its Tracer For The Mineralization

The volcanic rock of East Tianshan is composed of normal basalt, andesite, rich Nb basalt, magnesia andesite,adakite rock. The basalt has a characteristic of rich aluminum, high titanium, and low alkali. The trace element of the basalt has a characteristic of enrichment in the LREE and the LILE, relative loss in the HREE,The rich Nb basalt has the characteristics of positive Nb、 Ta anomaly. Magnesia andesite has a characteristic of high sodium, low alkali, enrichment of LREE;Adakite rock has a characteristic of low high Sr、Yb. The characteristics of εNd(t)from the basalt show that the main source of the basalt is mantle, at the same time it is contaminated by the earth’s crust material contamination. Adakite rocks with characteristics of relative high εNd(t)(εNd(t)= 6.55 ~ 9.06), is the result of partial melting of primary oceanic crust. Magnesia andesite is a blend of the slab-derived melts and mantle peridotite. The rock assemblage characteristics, geochemical characteristics, the characteristic of source rock characteristics and magma evolution and tectonic background, shows that this group of igneous rock is a product of subduction of oceanic ridge. The subduction of oceanic ridge has a importance for forming of the porphyry copper deposit in Tuwu and Yandong,at the same time is importance to the porphyry copper deposits in northern xinjiang.