Geological Characteristics And Genesis Of Xishimen Skarn Iron Deposit In Handan

Xishimen iron deposit is one of the typical Han-Xing-type iron deposit in southern Hebei,China. The deposit lies in the contact zone of the Middle Ordovician carbonate rocks and theYanshanian monzonite-diorite complex. In this paper, geological characteristics and genesis ofthe study is established based on metallogenic model. It provides a theoretical basis for furtherexploration. The conclusions are follow:1. Mineralization diorite pluton-monzonite rocks belong to calc-alkaline-alkaline rocktypes, with sodium-rich features, and Na2O> K2O.Xishimen forming U-Pb zircon dating results,the age is127±1.1Ma, indicates the Cretaceous magmatic activity in this area.Magma intrusionprocess, only partial melting also occurred in the presence of fractional crystallization,magmatic processes and crustal material involved in assimilation effects occurred.2. EW trending Kuangshan basement fault zone and Wuan basin margin NE fault zone ofKuangshan is to control the vertical upwelling of magma within the mining area the mainchannel. Layered rock mass and rock contact zone and the contact zone between thedepartment of rock layers in the fracture zone and folds collapse sliding structure, is the mainore-controlling structures.3. Wall-rock is the Middle Ordovician limestone Cixian.The main rock types aredolomitic limestone, and dolomite lime. They belong to calcium magnesium carbonate,and arethe most favorable wall-rock. The chemical composition of MgO and Cixian group brecciatedlimestones related to mineralization, as the most important rock prospecting prospecting layer.4. Field and laboratory study shows that the wall-rock alteration zone has obviouszonation. From the intrusion to carbonate rock，the alteration of wall rocks can be divided intofive alteration zones:albitization zone, albitite zone, skarn zone, ore zone and marble zone.There are gradual changes between the five alteration zones. Albitization zone and albitite zonecorrelate closely to mineralization. The iron extracted from alterated intrusion is the mainsource of ore-forming materials.The size of ore is in direct proportion to albitization zone andalbitite zone in scale and scope. Mineralization occurs mainly in skarn stage. Diopsidezationand phlogopitization are closely related with the mineralization. Albitization, diopsidezationand phlogopitization are the main indications of wall rock alteration for prospecting.5. Ore-forming materials mainly come from the surrounding rock albitization precipitation of iron, and a deep source of iron and iron-rich metamorphic basement rocks in the iron and theinvolvement of magma.Hydrothermal fluids come from magmatic water.Iron was in thehydrothermal fluids (Na, K)3[Fe3+Cl6],(Na, K)2[Fe2+Cl4],(Na, K)[Fe3+Cl4] complexforms of migration.δ34S‰range is16.4～18.4and the general magma sources S δ34S‰<10, showing that the sedimentary rocks of the gypsum may be the main source of S. Diopsideand carbonate which are rich in calcium caused the precipitation of iron.Mineralizationconcentrated in the temperature range between280-510℃. The occurrence of mineralizationmakes the fluid from high-density-high salinity to low salinity-medium density changes.6. By studying the geological characteristics of ore-forming conditions, the causes andlaw of mineralization, we established a metallogenic model, provided clues for prospectingexploration, and suggested directions for further exploration work.