Geochemical Characteristics And Geological Significance Of Qiakuertu Uranium-bearing Igneous Rock,Northeast Margin Of Junggar Basin

Junggar basin is located in the hinterland of central orogenic belt and lies between Siberian plate and Tarim plate in geotectonic. There are common development of igneous rocks around the basin. The research area Qiakuertu is located in the northeast edge of Junggar Basin and lies in the conjunction of Taerbahatai-Aermantai Trench arc belt and Beitashan compound Trench arc belt in geotectonic. The paper mainly discussed the petrology and geochemistry of uranium-bearing igneous rocks and their geological significance.The samples collected mainly included doleritic, dioritic porphyrite, pyroxene andesite, rhyolite and moyite. They all outcropped in the Batamayineishan formation of Upper Carboniferous. Most basic rocks belonged to the calcalkalic series while most intermediate and acid rocks belonged to high-K calcalkaline series,yielding a typical calcium alkaline sequence evolution trend and the characteristics of subduction zone volcanic rocks. There is a negatively correlated relationship between SiO2 content and major elements content with an obvious linear relation. This demonstrated that they might from the same source.Trace element model curve showed an enrichment of incompatible elements and is consistent with the typical epicontinental arc calc-alkaline volcanic rocks. The curves of basic, intermediate and acid igneous rocks were similar with each other and might be the product of cognate magma evolution. The trace element content ranged a lot and there was an obvious loss of Eu, Sr, Ba, P and Ti. These indicated that they have gone through strong minerals fractional crystallization. U had direct positive related relationship with major and trace elements.The change of δ18O value of the igneous rocks might be the result of the join of large amounts of meteoric water during the evolution of magma. The granite was I type from the partial melting of continental crust igneous. The tectonic background of the research area is complicated and is different from that of typical mid-ocean range and island-arc. It might be a certain transitional tectonic setting.The uranium metallogenic conditions of Junggar Basin and Tuha Basin was compared. They have similar geotectonic background, basement structure, cover layer and landscape-weather conditions. But the igneous rocks of southern margin of Tuha Basin were better in providing uranium than those of Junggar Basin. Besides, due to the strong structural movements of Junggar Basin, the existed metallogenic geological conditions were damaged by the later structural movements.Thus,uranium mineralization capability and potential prospecting was limited.