The Characteristics Of Ore Controlling Structure For Kaladawan Iron Ore-field In The North Altun Area, Xinjiang

The Kaladawan iron ore-field is geographically in the eastern of the North Altun area and is geologically located in the early Paleozoic active continental margin. It’s one of the few available deposits in the North Altun and has reached large scale, which both has economic value and research value. Compared with the major breakthrough in exploration, the research of ore-field structure is weak and full of controversy.Based on the predecessors’ research data, the new theory in the study of ore-field structure, detailed filed work and comprehensive analysis, we find out the structure styles which control the distribution of ore-body. Meanwhile, we propose the new structure model controlling ore and its evolution history to provide a theoretical basis for further prospecting prediction. And we get following main results and understanding:The surrounding strata are mainly upper Cambrain volcanic-sedimentary rocks in the Kaladawan ore-field, trending from West to East. And the ore body is stably located between the marble and basalt, which bends with the folding of ore-bearing strata. On the scale of ore-field, the ore-bearing strata and ore body constitute the NWW reclined-fold, which display the characteristics of strata-bound and fold-bound. The deformation features and formation age of the NWW reclined-fold show it’s the production of the southward subduction of the oceanic crust during～490Ma.The contact-zone between the marble and basalt is the significant metallogenic structural plane and the alteration zonation is the production of intense material exchange near the contact-zone. The ore body exposed in the contact-zone with the epidote and tremolite reflects the features of contact-zone-bound.The metallogenic material mainly comes from the volcanic rock strata and some with the lighter 556Fe may derive from magmatic hydrothermal. During the process of migration, the change of physical and chemical conditions (e.g. the temperature, Ph-value, Eh-value) make the ore-forming material convert from the volcanic rocks to the early alteration minerals, eventually into the magnetite.From the perspective of tectonic, the location of Kaladawan iron ore-field is contolled by the environment of early Paleozoic active continental margin. In the scale of ore-field, the NWW inclined-fold decides the distribution and extension of ore-bearing strata. And the location of ore-body is determined by the structure of contact zone. Meanwhile, the Kaladanwan Ore-field experience the process of the formation of source bed before 517Ma, the deformation of fold controlled by the southward subduction during-490Ma and the mineralization associated with the granitoid during 480-460Ma.The next prospecting ideas as follows:along the fold extension direction, the position of alteration zone has a good prospect; the strata and ore-body controlled by the inclined-fold extend far away in deepth, which means the great potential of deep exploration.