Mineralization Related To Post-collisional Mafic-Ultramafic Complex In North Xinjiang

A set of mineral deposits related to post-collisional mafic-ultramafic complex develops in north Xinjiang, i.e. copper-nickel sulfide (CNS) deposit, vanadic titianomagnetite (VTM) deposit and magnetite-cobalt (MC) deposit, which constitute a distinctive metallogenic spectrum in post-collisional tectonic evolution stage. The characteristics and intrinsic relationship of deposit types, and the deep tectonic environments of this metallogenic spectrum are the focus and urgent issues for post-collisional tectonic-mineralization of the Central Asia metallogenic province. Based on the study of previous results and by starting with typical deposit anatomy for some important types, this thesis has discussed the characteristics of mineral deposit, mineralization and metallogenic mechanism by means of research of field investigation, microscope observation, petrology, mineralogy, ore petrology, major and trace elements geochemistry, isotope chronology and isotope geochemistry, and comprehensive comparative analysis. In conjunction with the regional geological setting and mineralization contrast with relevant area, magmatism-mineralization model of the metallogenic spectrum is built up. Strategic regional prospecting prognosis and target also have been suggested in this PhD thesis. The main achieved advancements from this thesis are as follows:1. CNS deposits in the area are systematically studied, and a metallogenic model by multilevel intrusion-differentiation of mantle-derived magma is set up; It is discovered that hydrothermal fluid may participate in mineralization of CNS deposit; It is pointed out that hydrothermal activity and assimilation-hybridization are favorable factors to induce magma unmixing and to lead to sulfide liquation.2. For the first time, this thesis studies and confirms the Xiangshanxi CNS-VTM composite deposit, which reveals an intrinsic relationship between the CNS deposits and VTM deposits and offers a crucial evidence for building metallogenic spectrum related to mantle-derived magma in north Xinjiang.3. The Weiya VTM deposit in eastern Tianshan area is first in-depth studied and its metallogenic model is established, which supplies a gap of previous studies.4. A distinctive metallogenic spectrum is constructed in the thesis by in-depth study on the evolvement regularity and tectonic setting of mineralization related to mafic-ultramafic complex in north Xinjiang.5,A series of prediction criteria for prospecting of post-collisional CNS deposit and CNS-VTM composite deposit are summarized according to the results of theoretical research. Four strategic Cu-Ni deposit prospecting prognosis areas and three strategic CNS-VTM composite deposit prospecting prognosis areas are suggested.