The Genesis And Evolution Of The Huashugou Fe-Cu Association In The Western Sector Of The Northern Qilianshan

The Huashugou Fe-Cu deposit in the western sector of the Northern Qilianshanis an important type in Northwest China, its complicated formation process reflectsthe regional geological evolution history. The author made a detail study on this in thedissertation. The main achievements are as follows:1. The plate tectonic evolution of the west sector of the Northern Qilianshan hasbeen restructured. ①The Donghuang Group is composed of both Proterozoic andAchean, an age of 3488Ma is gotten. ②There might exist oceanic crust duringJixianian period based on the study of Xiaofengou ultrabasic rocks. ③ A newtectonic unit, Jianquanzigou Ordovician subduction complex, was founded, whichconsists of trench turbidites, ophiolites and radiolarian silicalites. ④ The Silurian is aset of Ⅰt ype sequence that include a lowerstand systems tract, a transgressivesystems tract and a highstand systems tract. ⑤ The Heixialao adamellite have beenconfirmed as a Caledonian syn-collisional ploton with an age of 345.5(±37)Ma. .2. The author made a thorough studied on the Huashugou Fe-Cu deposit. ①Two type of ores(phyllite-type and jasperite-type) have been reworked to differentdegrees by later reformation so that they can not be distinguished by geochemicalcharacteristics. ② The cluster analysis of the main elements of the deposit showsthat the formation of the Fe-Cu deposit is closely related to sedimentation. ③ TheREE features of the wall rocks, iron ores, copper ores, and quartz diorite are related toone another , showing that they are reformed by magmatic hydrothermal process todifferent extent. ④ Some characteristics of the deposit can be compared to otherSEDEX type deposits. ⑤The F10 is a contemporaneous fault, which reacted duringthe magmatic hydrothermal reformation stage, played an important role in theformation of the Huashugou Fe-Cu deposit. ⑥ The deposit is formed throughmulti-stage, with multi-resource, and by multi-origin.3. The formation of the Huashugou Fe-Cu deposit has been related to the platetectonic evolution of the western sector of the Northern Qilianshan and the formationof the deposit can be divided into three stages: ① during the sedimentation of theZhulongguan Group in a rift, submarine volcanoes have reserved ore substances forthe formation of the deposit;② during the sedimentation of the Jingtieshan Group,sedimentary exhalation formed the primal deposit;③ during late Caledonian, themagmatic hydrothermal in a subduction setting reformed the Huashugou Fe-Cudeposit, making Cu enrich more, and forming the deposit.4. The author has summarized the basic elements, processes, and products of themetallogenic system of the Huashugou Fe-Cu association in the western sector of theNorthern Qilianshan,and constructed a model for the origin of the Huashugou Fe-Cudeposit.5. The author has carried out metallogenic prediction according to the regionalmetallogenic features, marking off six prediction districts, that is of significance forfuture geological prospecting.