CAJ | 학술논문

查个勒铅锌矿床是西藏中冈底斯成矿带中段新发现的一个大型斑岩矽卡岩型矿床，但其成岩成矿时代一直缺乏年代学约束。本文对该矿床含矿斑岩进行了 LA ICP MS 锆石 U Pb 定年、辉钼矿Re Os 定年、主量和微量元素分析及 Sr Nd Hf 同位素组成研究，获得中冈底斯成矿带中段铜钼铅锌银矿化时代。含矿斑岩 LA ICP MS 锆石 U Pb 年龄为64．6～62．9 Ma ，代表岩浆的结晶年龄；辉钼矿 Re Os 等时线年龄为（62．3±1．4）Ma ，代表查个勒主成矿年龄，与其构造岩浆事件一致；结合区域林子宗群大规模火山活动（65～45 Ma）以及以亚贵拉铅锌矿床（68．6～65．0 Ma）为代表的成矿作用，表明在印度与欧亚大陆主碰撞过程中均可产生不同规模的成矿作用。查个勒含矿斑岩具富硅、富钾，贫钛、贫磷特征，铝饱和指数（A ／CN K）为1．12～1．60，富集大离子亲石元素 Rb 、Th 、U ，亏损高场强元素 Nb 、Zr 等，与冈底斯成熟大陆地壳物质相比具相对高的εNd （t）值（－6．64～－5．79）和相对低的（87 Sr／86 Sr）i 值（0．711813～0．717307），并具不均一的锆石εHf （t）值（－7．02～－1．27）以及古老的锆石 Hf 同位素地壳模式年龄（TCDM ＝1093～1419 Ma），属于过铝质 S 型花岗岩类。本文认为中冈底斯成矿带中段古新世岩浆活动和成矿作用，很可能与雅鲁藏布江洋盆闭合之后的印亚大陆碰撞诱发幔源岩浆底侵导致的冈底斯地体古老地壳物质部分熔融有关，岩浆在上升过程中有不同程度的分离结晶。
사개륵연자광상시서장중강저사성광대중단신발현적일개대형반암석잡암형광상，단기성암성광시대일직결핍년대학약속。본문대해광상함광반암진행료 LA ICP MS 고석 U Pb 정년、휘목광Re Os 정년、주량화미량원소분석급 Sr Nd Hf 동위소조성연구，획득중강저사성광대중단동목연자은광화시대。함광반암 LA ICP MS 고석 U Pb 년령위64．6～62．9 Ma ，대표암장적결정년령；휘목광 Re Os 등시선년령위（62．3±1．4）Ma ，대표사개륵주성광년령，여기구조암장사건일치；결합구역림자종군대규모화산활동（65～45 Ma）이급이아귀랍연자광상（68．6～65．0 Ma）위대표적성광작용，표명재인도여구아대륙주팽당과정중균가산생불동규모적성광작용。사개륵함광반암구부규、부갑，빈태、빈린특정，려포화지수（A ／CN K）위1．12～1．60，부집대리자친석원소 Rb 、Th 、U ，우손고장강원소 Nb 、Zr 등，여강저사성숙대륙지각물질상비구상대고적εNd （t）치（－6．64～－5．79）화상대저적（87 Sr／86 Sr）i 치（0．711813～0．717307），병구불균일적고석εHf （t）치（－7．02～－1．27）이급고로적고석 Hf 동위소지각모식년령（TCDM ＝1093～1419 Ma），속우과려질 S 형화강암류。본문인위중강저사성광대중단고신세암장활동화성광작용，흔가능여아로장포강양분폐합지후적인아대륙팽당유발만원암장저침도치적강저사지체고로지각물질부분용융유관，암장재상승과정중유불동정도적분리결정。
The newly discovered Chagele skarn‐porphyry deposit is located in the Middle‐Gangdese metallogenic belt . This study focuses on the zircon U Pb age of the ore‐bearing porphyry and molybdenite Re Os ,the whole rock major elements ,trace elements ,and the Sr Nd Hf isotopic data of the ore‐bearing rocks in Chagele deposit .The zircon U Pb age of the ore‐bearing porphyry changes from 64 .6 to 62 .9 Ma ,which represents the magmatic crystallization age .The Re Os isotopic age shows that the deposit was formed at (62 .3 ± 1 .4) Ma ,which is consistent with the magmatic age in the study area .Combing with the extensive volcanic event of Linzizong Group ,these new data suggests that the different scales of mineralization were formed at different stages in the entire collision between India and Eurasia continent .The ore‐bearing porphyry of Chagele deposit has high contents of SiO 2 ,K2 O , Rb ,Th ,and U ,coupled with low contents of TiO 2 , P2 O5 ,negative anomalies of Nb ,Zr ,variableεHf (t) ( - 7 .02 ~ - 1 .27) ,and ancient TCDM (1 093 ~ 1 419 Ma) .In comparison with the Gangdese continental crust composition ,the ore‐bearing porphyry is high in εNd (t) ( - 6 .64 ~ - 5 .79) and low in (87 Sr/86 Sr)i (0 .711 813 ~ 0 .717 307) .These geochemical features indicate that the porphyry of Chagele deposit is similar to the peraluminous feature of S‐type granite .The above discussion suggests that the Paleocene magmatism and mineralization in the middle section of the Middle‐Gangdese metallogenic belt could be formed through partial melting of the ancient crust materials of Gangdese micro‐continent accompanying with fractional crystallization ,which was probably induced by upwelling of mantle‐derived magma in the main collision between Indian and Eurasia continent .