古元古代-中国重要的成矿期

Paleoproterozoic-an Important Metallogenic Epoch in China

古元古代是中国十分重要的成矿期,矿种多、成矿规模大、矿床类型复杂。与太古宙相比,古元古代构造体制发生了本质的变化,由太古宙全活动体制转换为活动带和稳定地块并存的构造格局,因而其成矿特征与太古宙有明显差别。太古宙成矿主要与绿岩带有关,相应形成铁、金、铜锌等矿床。在古元古代,与成矿有关的构造环境主要是与拉伸、裂陷和伸展活动有关的裂谷环境,其次为活动大陆边缘裂谷及弧后盆地和被动大陆边缘盆地,有少部分与伸展构造有关,产在深大断裂带中的矿床。因而古元古代成矿是以裂谷、裂陷为主的成矿体系。在古元古代形成华北陆块北缘东段辽吉与古元古代裂谷作用有关的硼、铁、菱镁矿、滑石、铅锌、铜镍、岫玉等矿床成矿系列、华北陆块南缘中条山-王屋山与古元古代裂谷作用有关的铜矿床成矿系列、佳木斯微陆块与古元古代沉积变质作用有关的石墨、金矿床成矿系列等11个主要矿床成矿系列。相应大规模成矿的有铁、铜、金、铅锌、金红石、钛铁矿等金属矿床及石墨、菱镁矿、硼、滑石等非金属矿床。就是同一种矿产,与太古宙相比,矿床类型也有明显差别,如条带状铁建造(BIF)型铁矿,在太古宙为阿尔戈马型,而古元古代则以苏必利尔湖型为主。

Paleoproterozoic is an important metallogenic epoch in China.There are many mineral species,great metallogenic scale and complex type of ore deposits in this period.Compare with Archean,Paleoproterozoic is a transition period in which the active crust was changing into steady blocks and active belts.So,it shows different metallogenic characters from Archean＇s.In Archean,the main mineralization are iron,gold and copper zinc,which related with granite-greenstone belt.In Paleoproterozoic the metallogenic tectonic environment is mainly rift valley,active continental margin rift,back-arc basin and passive continental margin basin,and less deep-seated fault structure.So that Paleoproterozoic mineralization is mainly belong to rift metallogenic system.There are mainly 11 metallogenic series in Paleoproterozoic in China,for example,the metallogenic series of the borium,iron,magnesite,talc,lead zinc,copper nickel;Xiuyan jade ore deposits related to Paleoproterozoic rift valley of Liaoning-Jilin province;the metallogenic series of copper ore deposits related to Paleoproterozoic rift valley in the Zhongtiaoshan-Wangwushan of Southern margin of North China Craton;the metallogenic series of graphite,gold ore deposits related to Paleoproterozoic sedimentary metamorphism in the Jiamusi tiny land block.The iron,copper,gold,lead,zinc,rutile,ilmenite metallic ore deposits and graphite,magnesite,borium,talc nonmetallic ore deposits most formed in the Paleoproterozoic.Compare with the Archean,there is distinguishing difference of one type of ore deposits in the same mineral species,for example BIF type iron deposits,in Archean was Algoma type,in Paleoproterozoic was mainly Lake Superior type.