| The Haobugao lead-zinc deposit is located in the Xing-Meng orogenic belt between the North China Craton and the Siberia Craton.Representative large-scale deposits in the Huanggangliang-Ganzhuermiao polymetallic metallogenic belt in the south of Great Xing’an Range（referred to as the southern section）.One of the deposits is a typical skarn-type polymetallic deposit.In the Mesozoic Era,the southern section experienced multiple periods of strong magmatic activity,most of the deposits in the region are affected by magmatic-tectonic activity,and many magmatic rock bodies developed.There is a close connection with the ore body.The representative magmatic rock bodies exposed in the Haobugao are include xiaohanshan,wulandaba,wulanhundi,menghewula,bengbuleng rock mass and bengbulang vein,which are the products of Mesozoic diagenesis and mineralization.Based on the detailed field geological survey,combined with the regional geological background and geological characteristics of the deposit,this paper has carried out the whole rock master microanalysis,zircon U-Pb dating,Lu Hf isotope analysis,electron probe microanalysis and other methods,and made an in-depth study on the age,genesis,source area properties,structural background and evolution,and the change of metallogenic environment of magmatic rock mass in Haobugao are.The following understandings are obtained:The dating results of the magmatic bodies in the Haobugao area are 151.3±1.4 Ma（Wulandaba rock body）,150.3±0.54 Ma（Bengbuleng rock body）,145.0±0.74 Ma（Bengbuleng rock vein）,143.9±1.1 Ma（Xiaohanshan rock body）,142.46±0.31 Ma（Wulanhundi rock body）,and 134.33±0.28 Ma（Menghewula rock mass）.Combining the regional geological data and previous research results,the diagenetic age of the Bongbuleng rock body was redefined,and the Triassic,which was considered by previous authors,was determined to be the Late Jurassic,and the magmatic bodies in the region can be divided into three magmatic evolution sequences of 150~145 Ma,143~135 Ma and about 130 Ma.The analysis shows that the Wulandaba rock mass and the Bengbulang rock mass are the products of magmatism before mineralization,the Xiaohanshan rock mass is closely related to the mineralization of Haobugao lead-zinc deposit,the Wulanhundi rock mass is related to the mineralization of Wulanhundi lead-zinc deposit,and the Menghewula rock mass is the rock mass formed after the mineralization period.The overall trend in the trace element content of the magmatic bodies in the ore zone is similar;they are all enriched in Rb,U（LILE）and depleted in Ti,Y,P,Ba,Sr,and Nb.The pre-formation Bengbuleng and Wuandaba bodies are rich in silicon,deficient in aluminum,and relatively alkaline,with εHf（t）values ranging from 0.26 to 9.37.The two-stage model ages range from 442 to 982 Ma,and they appear to be Type I granites formed by partial melting of the newly formed crust in the lossy mantle,with the post-formation Menghewula body and Bengbuleng veins being highly Si-rich,Al-poor,and relatively alkali-rich.The former εHf（t）value ranges between 6.03 and 8.34,and the age of the two-stage model is between 467 and 612 Ma,indicating that it is a highly differentiated type I granite formed by partial melting of the new young crust in the lossy mantle,while the latter εHf（t）value ranges between 8.86 and 4.95,and the age of the two-stage-crustal Hf model is between 467 Ma and 612 Ma.The crustal Hf model has an age range of 698 to 1587 Ma,indicating the presence of highly differentiated I-type granites formed by partial melting of ancient crustal material in the source area,and the Xiaohanshan and Wulanhundi bodies associated with mineralization exhibit silica-rich,aluminum-deficient,and relatively alkali-rich characteristics,with εHf（t）values ranging from 3.70 to 8.86.Regarding the Hf model with two stages of crystallization,the age ranges between 632 Ma and 957 Ma,indicating that the A-type granite was formed by partial melting of the newly formed crust in the lossy mantle.When combined with the chronological characteristics,the Haobugao area’s magmatic body exhibits an evolutionary trend from I-type granite to highly differentiated I-type granite to A-type granite to highly differentiated I-type granite.Combining the results of previous research,the magmatic rock-tectonic evolution of the Haobugao area suggests that the late Eocene-Carboniferous period occurred in an oceanic crustal subduction environment;the Late Paleozoic-Early Mesozoic period occurred in a collisional orogenic environment;and the Late Jurassic-Early Cretaceous period occurred in a post-orogenic extension environment.The 150 Ma~135 Ma,the Haobugao area was in the post-orogenic extension environment,influenced by the upwelling of mantle material,the new crust of the deficient mantle and part of the remaining ancient crust were partially melted and formed magma along the area.The magma was formed,and the granite bodies were formed by multiple stages of tectonic uplift along the area.The mineralized hydrothermal fluid separated and precipitated after the magmatic period formed siliciclastic Pb-Zn deposits in favorable areas of mineralization. |
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