Geological Features, Mineralization Model And Prospecting Of Iron Deposits In Taxkorgan Region, West Kunlun Mountains

Geology, ore-controlling structures and metallogenic processes are studied through studying of trace elements, REE, stable isotopes and zircon U-Pb geochronology of the Taxkorgan iron deposits. The study is based on the regional metallogeny theory and detailed studies of geological settings, through comprehensive geological, geophysical and geochemical characteristics. The metallogenic genisis of the iron deposits were discussed and the main metallogenic epoch of the Taxkorgan region iron deposits were primarily identified. New metallogenic model are established. The metallogenic regularities are summarized and metallogenic prognosis in the region is figured out. The main conclusions are summarized as follows:1. Detailed studies of the geological characteristics, lithologic associations, metallogenic features, ore genesis and mineralization ages reveal that the iron deposits in Taxkorgan region are of Algoma-type banded iron ore deposit(BIF). They show many characteristics including tectonic setting, ore structures, ore types, mineral associations etc., similar to the typical Algoma-type BIF.2. LA-ICP-MS zircon U-Pb dating results show that the granite, dacitic porphyry, biotite quartz schist, amphibolitic gneiss, amphibolitic schist in the iron deposits of Taxkorgan region were formed at 2.42Ga~2.37 Ga, 2.0Ga~1.8Ga and 0.85Ga~0.5Ga, respectively. Systematic analysis of ore-forming ages suggests that the mineralization of the banded iron formation occurred at ca. 2.4Ga in Paleoproterozoic.3. Detailed field geological survey indicates that the Paleoproterozoic Bulunkuole Group is the main ore-hosting horizon. The ore bodies are largely concordant with the bedding of the stratigraphic layers. Ore types include banded and massive ores, followed by banding in marbles where they show transitional relationship with the wall rocks. In such a case, there are various types of ore minerals and alterations are well-developed. The formation of the iron deposits in Taxkorgan region experienced a period composed of deposition period, regional metamorphism period and magmatic hydrothermal reformation period.4. Geological features of ore deposits, geochemical characteristics and the isotopic compositions of rocks and minerals provide evidences that the magnetite is the product of primary sedimentary, and a large number of terrigenous clasts were involved in the ore-forming process. The iron deposits were formed mainly through primary sedimentary processes related to submarine mafic volcanic activities and metamorphosed during subsequent crustal evolution.5. Through analysis of geological factors of mineralization, the author summarizes the targeting indicators and builds a new exploration model, which provides reference for future prospecting of the same type of deposits.6. With detailed studies of stratigraphic, structural, magmatic and metamorphic controls on iron ore mineralization, the author summarizes the basic rules of temporal and spatial distribution of ore deposits, and mineral paragenesis characteristics. It is shown that the iron deposits in the Taxkorgan region is mainly are located within the Paleoproterozoic strata, and the occurrence of the deposits are controlled by stratigraphic horizons, lithology and volcano-sedimentary basin.7. Based on the results of previous research and the present study, a comprehensive prospecting model is established. Combining with large-scale geophysical and geochemical investigations, a total resource up to 20 to 25 million tons is estimated for the discovered ore deposits, ore bodies and ore occurrences in study area.