Regional Metallogenic System Of Alashan Block In Inner Monolia Autonomous Region

With the guidance of the metallogenic system theory, on the basis of field geologicsurvey, with the principal clue of the diagenetic and metallogenic isotopegeochronology and by applying new theories, new technologies and new methods, thegeological setting and evolution of regional metallogeny was studied for the purpose ofsystematically summarizing the basic geology, the geology of mineral deposits, isotopegeochronology, the metallogenic system and rule in the study area. The metallogenicprediction was conducted and the suggestion for the future exploratory allocation wasalso presented. The following is the research fruits:1. The hi-solution SHRIMP method, TIMS method and Sm-Nd isochron methodwere utilized and it is the first time to acquire the formation age of the Diebusige groupcomplex as 3018±49Ma and to define the age of ore-hosted formation in Zhulazagalarge gold deposit less than Qingbaikou System but not the MesoproterozoicZhaertaishan Group. The formation age of the Alashan group complex was collatedafresh to be 1920-2005Ma. It has been acquired a set of high precision data of volcanicand intrusive rock formation age. Thereafter, it is confirmed that there arePaleoproterozoic, Neoproterozoic, Eopaleozoic, Neopaleozoic and Mesozoic volcanicand intrusive rocks. And it is the first time to identify the volcanic and intrusive rock inthe Caledonian period in Oubulage area. The confusion of age classification of thegranite is clarified, which provides valuable data for the ore prospecting and basicgeology survey.2. A new understanding on the structural attribution and structural unit of theAlashan block was presented. Based on the tracing of multi-isotopes as Sm, Nd, Rb, Srand Pb, it is presented that Alashan block is a micro-landmass relative to theDaxing'anling-Mongolian Orogen belt but not the past being part of the North Chinaplaeocontinent or relative to Tarim plaeocontinent. Afterwards, Two II class, Four IIIclass and eight IV class structure units were sorted out.3. By applying the metallogenic system theory, the regional metallogenic system ofAlashan block was defined for the first time, and the metallogenetic assembly primarilyconsisting of the discrete epicontinental metallogenetic model, the convergentepicontinental metallogenetic model, the post-collision metallogenetic model and itsdeposit characteristics were systematically elaborated. The main ore deposit types andthe precise metallogenetic ages of Zhulazaga gold deposit, Hulaxibai gold deposit,Oubulage cupper-gold deposit, Kureng copper deposit, Zhusileng copper deposit,Chaganchulu gold deposit, Huheshala and Shalaxibie copper-iron deposits wereconfirmed.4. The study on the regional geochemical setting suggests that Au-Pb-Zn assemblywas enriched in the Paleoproterozoic base period in Alashan area;Au-Zn-Pd-Niassembly was enriched in the Mesoproterozoic Era in the covering bed period;Pd-Pt-Niassembly enriched in the Neoproterozoic Era;Ag-Sb-Mo-U-Pt assembly in theCambrian period;Au-Cu-U-Th-Ni-Zn in the Ordovician period;Pb-Mo-Zn-Th-Ag-Cu inthe Silurian-Devonian period;Cu-Pb-Zn-Au-Ag in the Carboniferous period;Au-Hg-Pb-Zn-Cu in the Permian period;and Th-Zn in the Mesozoic-Cenozoic Era. Theenrichment rules offers prospecting target in the study area.5. Metallogenic prospective areas of all classes are classified and the regional metallogeniclaw and metallotect are summarized. Established the regional matallogenic model andprospecting criteria for the type of strata-bound magmatic hydrothermal complited gold deposit,the volcanic-subvolcanic type of cupper-gold deposit and the skarn type of copper-iron deposit.The four important coupling events of crustal evolution and metallogenesis and themetallogenetic evolution phases are also presented. It is confirmed that the main prospecting oretypes consist of copper and gold deposit and the prospecting deposit types are the type ofoverlying stratum-controlled magmatic hydrothermal gold deposit and the volcanic rocktype-porphyry type-skarn type deposit.6. On the basis of integrated study on geological, geophysical and geochemical informationand metallogenetic laws, attempts to adopt the regional geochemical block to attainprospecting information , 54 potential geophysical and geochemical prospectingabnormities were selected and 7 geochemical prospecting anomaly zones wereclassified,nine V class metallogenetic prediction areas are screened and sorted, and fourresource evaluation suggestions on the metallogenetic prospect area in Alashan are put forward.