| The Duobaoshan ore concentration area is located in the northeast part of Xing’an–Mongolia orogenic belt, and west side of the boundary fault between Xing’an block andSongnen block. This area is a tectonic overprinting and conversion area by thePaleo–Asian tectonic domain, the Mongolia–Okhotsk tectonic domain and Paleo–Pacifictectonic domain. Due to the favorable ore–forming condition, large number and volume ofore deposits as well as composite genetic types, this area has been the hot–point area forboth ore–prospecting and metallogenic theory for tens of years.In order to reveal regional mineralization and metallogenic regularity in the Duobaoshanore concentration area, basing on previous research production, the author chooses sevenrepresentative deposits (including Duobaoshan and Tongshan copper–molybdenumdeposits, Zhengguang gold deposit, Sankuanggou iron–copper deposit, Yubaoshancopper–iron deposit, Xiaoduobaoshan copper deposit and Huaduoshan copper–molybdenum mineral occurrence), and studied their geological features, deposit types,mineralization age, ore–forming materials resource and geodynamic background,metallogenic model and metallogenic regularities. Several conclusions have been drawn asfollows:1. The Triassic magmatic metallogenic events in Duobaoshan ore concentration areahas been recognized for the first time. Zircon U–Pb weighted mean ages of the tonalite inthe Duobaoshan deposit, the porphyritic granite in the Tongshan deposit, and the granite porphyry and granodiorite in the Xiaoduobaoshan deposit are230.9±2.3Ma,235.4±2.7Ma,226.6±1.7Ma, and232.8±1.7Ma, respectively. The Re–Os model age of themolybdenite in the Tongshan porphyritic granite is229.4±3.5Ma, indicating that theDuobaoshan ore concentration area experienced a Triassic magmatic–mineralizationevent.2. Ore deposits in the Duobaoshan ore field can be categorized into at least four types:porphyry copper–molybdenum deposits (Duobaoshan, Tongshan and deep Zhengguang),skarn copper (iron or molybdenum) deposit (Sankuanggou, Yubaoshan and Xiaoduobaoshan),epithermal gold deposit (Zhengguang) and crptoexplosive–breccia–rock type deposit(Huaduoshan).3.The Duobaoshan region has experienced at least four major magmatic–mineralizationevents: the Ordovician porphyry copper–molybdenum mineralization in the Duobaoshanand Tongshan deposits, the Triassic skarn copper mineralization in the Xiaoduobaoshandeposit and the porphyry copper–molybdenum mineralization in the Tongshan deposit, theEarly Jurassic skarn copper (iron) mineralization in Sankuanggou and Yubaoshan depositsand crptoexplosive–breccia–rock mineralization in Huaduoshan deposit, and the LateJurassic–Early Cretaceous event resulted in the epithermal Au mineralization in theZhengguang deposit.4. The source materials and geological background of intermediate acid intrusiverock formed in different stage have been determined. The early Cambrian Zhengguangdiorite, relationship with Pan African orogeny oceanic crust subduction, has adakiteproperty. Early Ordovician Duobaoshan granodiorite also with the adakitic geochemistryformed in collision and suturing between Xing’an block and Ergun block; middle Triassictonalite, which shows geochemistry properties of island arc magmatic rocks, has closerelationship with the Mongolia–Okhotsk plate subduction; early Jurassic acid intrusiverocks, which shows geochemistry properties of island arc magmatic rocks, has closerelationship with the Paleo–Pacific plate subduction.5. The ore–forming materials source, ore–forming fluid and metallogeniticmechanism have been discussed in this thesis. The intensive multiple fluid boiling is the main mechanism of Caledonian porphyry copper (molybdenum) mineral deposits. InIndosinian, ore–forming materials mainly come from mantle and ore–forming fluid mainlycomes from magmatic water. The early Yanshanian ore–forming materials are mixed bycrust–mantle materials, the intensive multiple fluids boiling played the important roles inmineralization. In late Yanshanian, ore–forming materials mainly come from mantle but alittle from crust and ore–forming fluid is characterized by mixing fluid.6. The metallogenic regularities of the Duobaoshan ore concentration area has beenconcluded by studying regional ore–forming conditions, rock–forming age andore–forming age and it’s evolution, spatial distribution regularities of deposit. Firstly,alumina–rich and high acid Adakite rock, which connected with middle OrdovicianDuobaoshan group strata. NW–extending faults, is the important ore–forming geologiccondition. Secondly, from the Early Paleozoic to Late Mesozoic, the deposit genesisregularly change, and mineralizing depth get shallower and shallower; Thirdly, from NWto SE in the ore concentration area, the deposit genesis changes from the sharn, porphyryto epithermal type. In addition, multi–phase superimposed mineralization may be the mainreason for forming the Duobaoshan ore concentration area. Based on such results, thisthesis analyzes the regional ore indications and further geological prospecting. |
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