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The etouchang-typeiron deposit is a typical stratabound deposit in the northern 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 valley-type trough appeared between the Lüzhijiang fault zone and the Luoci-Yimen fault zone. It was along the marginal areas of the trough 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, themigration and enrichment of iron substance and the formation of economic deposits. The LuociYimen 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 enricbment 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.
The etouchang-typeiron deposit is a typical stratabound deposit in the northern part of central Yunnan. The discussion centers 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. Preparation of 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 NS rift valley-type trough occurred between the Lüzhijiang fault zone and the Luoci-Yimen fault It was along the marginal areas of the trough that the iron-rich clay and sand of dominant terrigenous origin were accumulated, constitute the source bed of iron. During the Jinning movement, the basement had been formed and the longitudinal structural system took shape of the Chengjiang movement, the longitudinal structural system was strengthened and the central Yunnan xi-type structure, which controlled the activities of the Na-rich magma and thermal fluids, and the consequent reformation of the source bed, their migration and enrichment of iron substance and the formation of economic deposits. The LuociYimen fault zone controlled the distribution of the iron orefield while the lateral structures (eg, the Etouchang compounding shear structure) controlled the occurrence of the deposit. The reformation and enricbment 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.