秦岭造山带构造-成矿旋回与演化

构造与成矿活动是否具有旋回性是地质界长期争论的一个命题。本文根据矿床成矿系列理论和方法,论述了秦岭造山带构造-成矿活动,划分出新太古代-古元古代早期、古元古代晚期、中-新元古代、早古生代、晚古生代和中、新生代6个构造-成矿旋回,探讨了每个旋回的矿床成矿系列特征和成矿演化历史。指出该造山带的成矿作用既有长期性和连续性,也有间断性和旋回性;中、新元古代至早古生代和中、新生代两个时期是秦岭造山带中两个主要的成矿高峰期;构造-成矿作用可分为开裂、拼合及相对稳定三个阶段;成矿作用早期以幔源岩浆侵入及海相火山活动为主,晚期以壳幔混源-壳源的陆相中酸性岩浆侵入及火山活动为主;与火成活动及开裂作用有关的成矿活动在南、北两个成矿域之间具有振荡性演化的特征. 

TECTONO-MINEROGENIC CYCLES AND MINEROGENETIC EVOLUTION THROUGH GEOLOGICAL HISTORY IN THE QINLING OROGENIC BELT

It has been disputed for a long time whether tectonic and minerogenic cycles did ever exist through geological history.On the basis of the theory and method of the minerogenic series of ore deposits,the authors advanced and discussed a concept of "tetono-minerogenic cycle".Cyclicity of tectono-minerogenic activities in the Qinling orogenic belt is systematically discussed in this paper,and six tectono-minerogenic cycles are drawn:(1) from the Latest Archean to the initial Proterozoic;(2) the Early Proterozoic;(3) Middle Proterozoic and the Late Proterozoic;(4) the Early Paleozoic;(5) the Late Paleozoic and (6) Mesozoic to Cenozoic.Minerogenic evolution is duscussed by a summarization of the characteristics of each of the six minerogenic cycles.The mineralization in the Qinling orogenic belt was either long and continuous or intermittent and cyclic.Many of the ore deposits are formed in two major peak mineralization periods,one is from the Middle Proterozoic to the Early Paleozoic,characterized by mantle-derived magmatic intrusions and marine volcanism;the other is from the Mesozoic to the Cenozoic,during which the intermediate and acid magmatic intrusions and continental volcanism are mainly derived from the crust or with a mantle-crust source.The 24 minerogenic series of ore deposits in this orogenic belt are considered to have formed in three major types of tectono-minerogenic processes,ie splitting,convergence,and a relatively stable stage.The mineralization associated with volcanism and splitting would have experienced a vibration between the north and south Qinling orogenic belt through out the geological history.