Ore Controlling Structure And Metallogenic Regularity Of The Hutouya Ore Field In Qimantage Area

The tectonic position of Qimantage area is in the Qimantage early Paleozoic suture zone,and north to south from the Qaidam Massif to the Compound magmatic arc of the earlyPaleozoic-late Paleozoic. The region hace a well-exposed of strata, various tectonic conditions,complicated ore-bearing horizon, repeated tectonic movements and frequently to magmaticactivity. The Qimantage possess such mineralization geological condition of porphyrydeposit+skarn type deposit+hydrothermal type+submarine spouting hydrothermalsedimentary type.Hutouya orefield is located in the heart of Qimantage metallogenic belt, and belongs toone of the most important polymetallic deposits. Through the analysis of ore-controllingstructure and skarn deposit, the research have made a number of promising achievements.It is mainly discuss the determination of the relation of time and space betweenore-controlling structure and mineralization process.1）Pre-mineral periods structure mainlyincludes Kunbei faults and its secondary fault，and was formed in early Paleozoic.Thestructure provided migratory channels of the hydrothermal solution, and belongs to the mainleading structure.2）Metallogenic periods mainly includes NWW, nearly EW and NEEstructures, and was formed in the Late Paleozoic-earlyMesozoic. The contact zones, faults,interface of the different lithological character and anticlinal constitute the secondary structureof Hutouya orefield.3）The post-mineralization mainly includes NE and nearly SN structures.By studying the tectonic stress field, deformation age and the determination the relation oftime and space between ore-controlling structure and mineralization process, we can plottedto three periods tectonic stress field.This is the first systems research study for faultedstructures, joints and ductile faults of the area, and it is proposed that the structural stress fieldcan be divided into pre-mineral periods (NNE-SNâ†'NNEâ†'NNW), metallogenic periods(NNE-SN-NNW) and post-mineralization (NW-NWWâ†'NEE-EWâ†'SN). The researchshows that the evolution of principal stress direction is consistent with regional tectonicmovement, and establishs fundamental principles to analysis of the tectonic stress field inQimantage area.Genetic analysis of skarn: the recover of the skarn shows protolith belongs to carbonatite;the analysis for variable realrtion of common element shows characteristic of the contactmetasomatic skarn type; correlational analyses of common element for siliceous rocks showsthe geochemical features of the biogenic deposition. Above all, the analysess of common element and trace elements for intrusions, skarn, ore and carbonatite, show the forming of thedeposit has s genetic relationships with monzonitic granite, quartz porphyry and so on.Metallogenic model:the within-plate extension of the early-middle Variscan and theIntracontinental collision of the early Indosinian, made different geologic bodies in blockfaults. The magma of the mixture of crust and mantle which was from extension environmentof the late Indosinian, flowed along the Kunbei large fault from deep to shallow, and thenformed porphyroid monzonitic granite, quartz porphyry and syenogranite which is controledby secondary structure. At last, under combined effect of intrusions and surrounding rock,contact metasomatic skarn type deposit and fault-control hydrothermal type deposit areformed.