摘要
滇中北部的鹅头厂式铁矿是一种典型的层控矿床。在矿床形成的过程中,构造起着双重的控制作用,即:东川运动之后的经向构造体系萌芽期,南北向的裂谷式海槽控制了矿源层的形成;晋宁—澄江运动时的经向构造体系定型和发展期,由南北向的罗次-易门断裂带派生的多字型构造控制了矿源层的改造,以及成矿物质的转移、富集和矿床的形成。因此,这类矿床是构造体系成生、发展控制层控矿床形成和分布的典型实例。
The Etouchang-type iron deposit is a typical stratabound deposit in the northorn part of central Yunnan.The discussion centres on the controlling effect of the generation and development of the structural system in the orefield on the formation of this type of deposit and establish a time-space ore-control model so as to get a better understanding of the mechanism for its formation.During the formation and enrichment of the Etouchang-type iron deposit,the structures performed a dual control function on the generation and distribution and also on the reformation and enrichment of the source bed.The Etouchang-type iron deposit is a typical example for the stratabound deposits of which the formation and distribution are controlled by the generation and development of structural systems.During the embryonic period of the longitudinal structural system shortly after the Dongchuan movement,a N-S rift valleytype trough appeared between the Luzhijiang fault zone and the Luoci-Yimen fault zone.It was along the marginal areas of the trought that the iron-rich clay and sand of dominant terrigenous origin were accumulated,constituting the source bed of iron.During the Jinning movement the basement had been finally formed and the longitudinal structural system took shape.During the Chengjiang movement,the longitudinal structural system was strengthened and the central Yunnan Xi-type structure appeared,which controlled the activities of the Na-rich magma and thermal fluids,and the consequent reformation of the source bed,the migration and enrichment of iron substance and the formation of economic deposits.The Luoci-Yimen fault zone controlled the distribution of the iron orefield while the lateral structures(e.g.the Etouchang compounding shear structure)controlled the occurrence of the deposit.The reformation and enrichment of the Etouchang-type iron deposits were concomitant with the formation of an ore-controlling structure.The scale and grade of the orebodies were strictly controlled by the structural pattern,and the orebodies occurred in the shear structures and were enriched in the tensional portion of a compressive structure.
作者
孙家
Sun Jiacong(Department of Geology,Kunming Institute of Technology,Kunming,Yunnan)
出处
《地质学报》
1986年第3期275-285,共11页
Acta Geologica Sinica
