秦岭地区主要金属矿床成矿系列的划分及区域成矿规律探讨

本文根据我国公路建设项目投资、融资体制改革的发展趋势，阐述了改进公路建设项目可行性研究财务评价工作的重要意义及改进财务评价方法的原则，提出改进财务评价方法的途径。针对当前公路建设项目可行性研究财务评价的现状，提出了财务评价工作应注意几个问题，供有关部门参考。

Metallogenic series of main ore deposits and regional metallogeny in the Qinling area

Twenty-one metallogenic series of main Ore deposits from the Late Archean to the Mesozoic in the Qinling area have been distinguished, comprising one in the Late Archean, four from the Middle to the Late Proterozoic, three from the Late Proterozoic to the Lower Paleozoic, three in the Caledonian(including the Late Caledonian-Early Hercynian), one in the Hercynian, six in the Mesozoic and two whose metallogenie epochs are unidentified. Metallogenic processes of ore-forming elements such as Mo, Au, Ag, Pb, Zn, Hg, Sb, Nb, REE and U mostly took place in the area, and there is a wide variety of genetic types of deposits. Most of the metallogenic series of deposits are related genetically to magmatic intrusions and eruptions, with early (from the Late Archean to the Lower Paleozoic)ones to the basic-ultrabasic intrusions and the bimodality pattern marine volcanism resulting from spreading rifting and deep fauIting and the late (from the Late Paleozoic to the Mesozoic) ones to intermediate-acid intrusions and terrestrial volcanism, generated by conversion of tectonic environments from ocean to intracontinent. The ore-forming materials were derived mainly from deep-seated sources, showing that the tectonomagmatic activities reached very great depths. There are two important metallogenic ages: one is the Middle Proterozoic-Early Paleozoic during which the metallogenetic processes were related to the spreading rifting; the other, related to the intracontinental subduction, is the Mesozoic. The Early Proterozoic metallo genesis was quite weak. The regional metamorphism and high-pressure dynamo-metamorphism exerted remarkable effects on the formation of iron, gold, uranium, ruffle and blue asbestos ore deposits. Sedimentary metallogeneses, which must have brought about the formation of iron, manganese, lead, zinc and vanadium ore deposits, occurred largely in the Late Axchean, the Paleozoic and the Mesozoic. There are metallogenetically marked differences between the eastern Qinling and the western Qinling divided by longitude 106°E as a boundary. The distributions of deposits are mostly controlled by the EW-NWW striking structures, on which the Yanshanian NE-striking structures were superimposed later. Metallogeneses in the area are characterized by inheritance, polyphases, polysources and polygenesis. Many times of strong tectonic movements and their distinction in time and space played a dominant part in the formation of the unique metallogenic features in the Qinling area.