Abstract:
Abstract:Mineralizations in Central Asia and adjacent areas were dominated by C, B, P, Mg, Au, Fe and Cu in the early stage (in Precambrian) of evolution of the earth, and by Al, Pb, Zn, W, Sn, Mo, Hg and Sb in the late stage (in late Phaneozoic). Carbon (graphite) dominated in Precambrian might have been related to the low oxygen fugacity in the crust and the atmosphere in the early stage of the earth; in that case carbon was not easy to be oxidized. B and P are volatile elements, hence their enrichment in Precambrian may imply that the crust was relatively enriched with B and P in the early stage of the earth. Mg, Fe and Au compositions indicate that the crust was rich in these elements at that time. Cu mineralization took place repeatedly in Proterozoic, Paleozoic and Mesozoic. Economically important Al deposits, i.e., bauxite deposits, presented peak mineralization in Carboniferous and Permian, as can be seen in China. Pb, Zn, W, Sn, Mo deposits were formed in Mesozoic. Hg and Sb, though primarily deposited in Paleozoic, were mainly formed in Mesozoic, even later than Pb, Zn, W, Sn, Mo mineralizations. In the Periodic Table, C, B,P, Mg and Al belong to Periods 2-3. The mineralizations of these elements mainly took place in Precambrian; Fe, Au, Cu, Pb, Zn, W, Sn, Mo, Hg and Sb belong to Periods 4-6. Mineralizations of these elements mainly took place in the late stage of the evolution of the earth. Uranium (U) belongs to Period 7. The U mineralization in China almost all appeared after mineralizations of W, Sn, Mo, Bi, Fe, Cu, Zn, Nb, Ta and REE. In other words, in the evolutionary history of the earth, the atomic structures of ore-forming elements become more and more complex, while the outer electronic layers increase from 2 or 3 layers (C, B, P, etc.) up to 7 layers (U).In ore-prospecting, therefore, to look for mineral deposits of the elements in the upper part of the Periodic Table, we should conduct relevant prospecting work in old crustal regions (Precambrian regions); to look for those in the middle part of the Period Table, we should take into account both old and young crustal regions; to look for those in the lower part of the Periodic Table, we should carry out relevant work in the regions where young geological, tectonic, magmatic and hydrothermal activities are developed.Since Phanerozoic, especially since Late Paleozoic and Mesozoic, further developments of the hydrosphere, atmosphere and biosphere have made the evolutionary tendency further complicated; the formation of sedimentary deposits,especially the recycles of C, H and O, have resulted in the generation of large amounts of coal, petroleum and natural gas.