| Large sales of ultramafic rocks were produced in Paleozoic in Northern Xinjiang, China, and magmatic deposits of significance were developed. The Paleozoic basalts from Junggar basin plays an important role for studying the Paleozoic ultramagmatism of the basin and its tectonic evolution history. In this thesis, we have collected Paleozoic basalt cores from oil exploration team and conducted petrogeochemistry and volatile geochemical study and comparison, which is of significance for understand the genesis and evolution of Carboniferous basalts from Junggar basin, and discussed its geological implications. Five conclusions are list below:1. The Carboniferous basalts studied are low in SO2(45.39%-50.47), CaO and MgO, high of TiO2 and PaO5,and medium of Al2O, lie in basalts area in TAS pattern, which is deviated for the right. LREE are enriched, Eu lightly depleted.Active elements such as Sr, K, etc, are depleted, high field-strength elements are high, and large ion lithophile elments are obviously delepleted.2. Chemical compositions of basalt volatiles:The volatiles are mainly H2O, CO2, O2, N2, and also consisted of some CH4,C0, H2. For the total amount of gases released from samples by heating, it is found that gases are mainly released from three different temperature intervals,200℃～400℃,400℃～800℃,800℃～1100℃, and 400℃～800℃ interval amounts for the largest volume ratio in gases volume, about 2500mm3.STP/g in average.3. Volatiles carbon isotopes:δ13CCO2 is -27.234‰～-16.69‰, and δ13CC2H6, δ13CC4H10,δ13CC3H8, and δ13CCH4 are respectively -29.32‰～-20.738‰,-23.25‰～-18.967‰,-25.364‰～-15.321‰.4. Magma evolution:The negative abnormal of Sr and Eu suggest some scales of crystallization and differentiation of plagioclase, and low Mg value indicates a strong evolution.High incompatible element content and low Th/Nb ratio and arc volcanic characteristics show that basalts were generated under an extensional environment after post collision. |
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