Erdaohezi lead-zinc deposit belongs to the Derbugan metallogenic belt lying on the northwestern Hailaer-Genhe Mesozoic volcanic basin, located on the western slope of the Da Hinggan Mountains. The deposit is considere...Erdaohezi lead-zinc deposit belongs to the Derbugan metallogenic belt lying on the northwestern Hailaer-Genhe Mesozoic volcanic basin, located on the western slope of the Da Hinggan Mountains. The deposit is considered as one of the hypabyssal low-temprature hydrothermal lead-zinc deposits associated with volca- nism. In order to lay the foundation on studying its diagenesis and mineralization ages, the detailed studies were carried out by dating the host rocks （i. e. rhyolitic lithic-crystal tufts） using zircon LA-ICP-MS U-Pb method. The dating results show three groups ot! ages. The first group is the captured zircons （the weighted mean ^206pb/238U age as 175.6± 2.3 Ma, MSWD = 0.70, n = 3）. The second group can be regarded as the rock- forming age （the weighted mean ^206pb/238U age as 165.3± 1.9 Ma, MSWD = 2.40, n = 14）. The third group should represent the late stage of the magmatic evolution （the weighted mean ^206pb/238U age as 161.0 ± 3.1 Ma, MSWD = 0.86, n = 4）. According to the ages and the crystal form or CL image characteristics of zircons, it is determined that the diagenesis occurred in the late Middle Jurassic. Based on the regional geology and geo- chronological research, the acidic pyroclastic rocks are space accompaniment and time connection with the Tamu- langou Formation intermediate-mafic volcanic rocks. Both of them constitute the host rocks of the deposit together. The rock combination also provides favorable conditions for large-scale silver, lead and zinc mineralization in this area.展开更多
The south Gangdese region is the site of subduction of the Neo-Tethys and subsequent continental col- lision. Compared with widespread Cretaceous and Cenozoic magmatism, Early-Middle Jurassic magmatic rocks and relate...The south Gangdese region is the site of subduction of the Neo-Tethys and subsequent continental col- lision. Compared with widespread Cretaceous and Cenozoic magmatism, Early-Middle Jurassic magmatic rocks and related deposits are rarely reported, Our work identified a 〉200 km long felsic rock belt asso- ciated with Cu mineralization in the south Gangdese region. We report here zircon U-Pb ages, zircon Ce4＋/Ce3＋ values, and mineral assemblages of two Cu mineralized intrusions within the belt. A horn- blende granite and a diorite porphyry were emplaced at 177.3Ma and 166.3Ma, respectively. Geological occurrence and magmatic hematite-magnetite-chalcopyrite intergrowths suggest that Cu mineralization formed coeval with Jurassic intrusions. Mineralized intrusions have high zircon Ce4＋/ Ce3＋ and EuN/EuN ratios, and hematite-magnetite intergrowths, suggesting their parent magmas were highly oxidized, Hornblende is common and primary fluid inclusions are found in titanite and apatite, indicating their parent magmas were water-saturated and exsotved volatile phases at early stage of rnag- matic evolution. Those magma characters contribute to the formation of porphyry Cu deposits. Given that majority subduction-related porphyry Cu systems have been eroded following uplift and denudation, the well-preserved Early-Middle Jurassic cu mineralized igneous rocks in south Gangdese are favorable prospecting targets for subduction-related porphyry Cu deposits.展开更多
基金Supported by National Natural Science Foundation of China(No.41390444)
文摘Erdaohezi lead-zinc deposit belongs to the Derbugan metallogenic belt lying on the northwestern Hailaer-Genhe Mesozoic volcanic basin, located on the western slope of the Da Hinggan Mountains. The deposit is considered as one of the hypabyssal low-temprature hydrothermal lead-zinc deposits associated with volca- nism. In order to lay the foundation on studying its diagenesis and mineralization ages, the detailed studies were carried out by dating the host rocks （i. e. rhyolitic lithic-crystal tufts） using zircon LA-ICP-MS U-Pb method. The dating results show three groups ot! ages. The first group is the captured zircons （the weighted mean ^206pb/238U age as 175.6± 2.3 Ma, MSWD = 0.70, n = 3）. The second group can be regarded as the rock- forming age （the weighted mean ^206pb/238U age as 165.3± 1.9 Ma, MSWD = 2.40, n = 14）. The third group should represent the late stage of the magmatic evolution （the weighted mean ^206pb/238U age as 161.0 ± 3.1 Ma, MSWD = 0.86, n = 4）. According to the ages and the crystal form or CL image characteristics of zircons, it is determined that the diagenesis occurred in the late Middle Jurassic. Based on the regional geology and geo- chronological research, the acidic pyroclastic rocks are space accompaniment and time connection with the Tamu- langou Formation intermediate-mafic volcanic rocks. Both of them constitute the host rocks of the deposit together. The rock combination also provides favorable conditions for large-scale silver, lead and zinc mineralization in this area.
基金supported by Strategic Priority Research Program of Chinese Academy of Sciences(XDB03010302)the DREAM project of MOST,China(2016YFC0600407)a contribution No.IS-2396 from GIGCAS
文摘The south Gangdese region is the site of subduction of the Neo-Tethys and subsequent continental col- lision. Compared with widespread Cretaceous and Cenozoic magmatism, Early-Middle Jurassic magmatic rocks and related deposits are rarely reported, Our work identified a 〉200 km long felsic rock belt asso- ciated with Cu mineralization in the south Gangdese region. We report here zircon U-Pb ages, zircon Ce4＋/Ce3＋ values, and mineral assemblages of two Cu mineralized intrusions within the belt. A horn- blende granite and a diorite porphyry were emplaced at 177.3Ma and 166.3Ma, respectively. Geological occurrence and magmatic hematite-magnetite-chalcopyrite intergrowths suggest that Cu mineralization formed coeval with Jurassic intrusions. Mineralized intrusions have high zircon Ce4＋/ Ce3＋ and EuN/EuN ratios, and hematite-magnetite intergrowths, suggesting their parent magmas were highly oxidized, Hornblende is common and primary fluid inclusions are found in titanite and apatite, indicating their parent magmas were water-saturated and exsotved volatile phases at early stage of rnag- matic evolution. Those magma characters contribute to the formation of porphyry Cu deposits. Given that majority subduction-related porphyry Cu systems have been eroded following uplift and denudation, the well-preserved Early-Middle Jurassic cu mineralized igneous rocks in south Gangdese are favorable prospecting targets for subduction-related porphyry Cu deposits.
