吉林大学学报(地球科学版)
吉林大學學報(地毬科學版)
길림대학학보(지구과학판)
Journal of Jilin University (Earth Science Edition)
2015年
5期
1394-1404
,共11页
刘金龙%孙丰月%林博磊%王冠%许庆林%奥琮
劉金龍%孫豐月%林博磊%王冠%許慶林%奧琮
류금룡%손봉월%림박뢰%왕관%허경림%오종
锆石UPb年龄%地球化学%金沟岭组%粗面安山岩%活动大陆边缘%闹枝金矿
鋯石UPb年齡%地毬化學%金溝嶺組%粗麵安山巖%活動大陸邊緣%鬧枝金礦
고석UPb년령%지구화학%금구령조%조면안산암%활동대륙변연%료지금광
zircon U Pb chronology%geochemistry%Jingouling Group%trachyandesite rocks%active continental margin%Naozhi gold deposit
对延边闹枝金矿区金沟岭组粗面安山岩进行了锆石 LA ICP MS U Pb 年代学和地球化学特征的研究,结果表明:金沟岭组粗面安山岩中的锆石自形程度较好,主要为长柱状,具有较为清晰的韵律环带结构,Th/U 值为0.43~0.71(>0.40),表明锆石岩浆成因;锆石定年结果显示,金沟岭组粗面安山岩形成时代为早白垩世((130±2)Ma ,MSWD =1.8);岩石属于钙碱性系列,明显富集大离子亲石元素(如 K 、Ba 、Rb)、LREE 和强不相容元素(如 Th 、U ),相对亏损高场强元素(如 Ta 、Nb 、Ti 、P),高 Mg #值(43~52,平均为47),Na2 O/K2 O 值为1.73~2.25,平均值为1.93(>1.17),其地球化学特征与活动大陆边缘背景下形成的火成岩相似。结合岩石 Nb/Ta 值(14.40~14.72)、Rb/Sr 值(0.10~0.18)、Th/Nb 值(0.29~1.04)、Ba/La 值(17.61~23.92)等特征值,认为岩浆由壳幔混合而成。综合前人研究成果,认为金沟岭组粗面安山岩形成于古太平洋(伊泽奈崎)板块斜向俯冲亚洲大陆的活动陆缘环境。
對延邊鬧枝金礦區金溝嶺組粗麵安山巖進行瞭鋯石 LA ICP MS U Pb 年代學和地毬化學特徵的研究,結果錶明:金溝嶺組粗麵安山巖中的鋯石自形程度較好,主要為長柱狀,具有較為清晰的韻律環帶結構,Th/U 值為0.43~0.71(>0.40),錶明鋯石巖漿成因;鋯石定年結果顯示,金溝嶺組粗麵安山巖形成時代為早白堊世((130±2)Ma ,MSWD =1.8);巖石屬于鈣堿性繫列,明顯富集大離子親石元素(如 K 、Ba 、Rb)、LREE 和彊不相容元素(如 Th 、U ),相對虧損高場彊元素(如 Ta 、Nb 、Ti 、P),高 Mg #值(43~52,平均為47),Na2 O/K2 O 值為1.73~2.25,平均值為1.93(>1.17),其地毬化學特徵與活動大陸邊緣揹景下形成的火成巖相似。結閤巖石 Nb/Ta 值(14.40~14.72)、Rb/Sr 值(0.10~0.18)、Th/Nb 值(0.29~1.04)、Ba/La 值(17.61~23.92)等特徵值,認為巖漿由殼幔混閤而成。綜閤前人研究成果,認為金溝嶺組粗麵安山巖形成于古太平洋(伊澤奈崎)闆塊斜嚮俯遲亞洲大陸的活動陸緣環境。
대연변료지금광구금구령조조면안산암진행료고석 LA ICP MS U Pb 년대학화지구화학특정적연구,결과표명:금구령조조면안산암중적고석자형정도교호,주요위장주상,구유교위청석적운률배대결구,Th/U 치위0.43~0.71(>0.40),표명고석암장성인;고석정년결과현시,금구령조조면안산암형성시대위조백성세((130±2)Ma ,MSWD =1.8);암석속우개감성계렬,명현부집대리자친석원소(여 K 、Ba 、Rb)、LREE 화강불상용원소(여 Th 、U ),상대우손고장강원소(여 Ta 、Nb 、Ti 、P),고 Mg #치(43~52,평균위47),Na2 O/K2 O 치위1.73~2.25,평균치위1.93(>1.17),기지구화학특정여활동대륙변연배경하형성적화성암상사。결합암석 Nb/Ta 치(14.40~14.72)、Rb/Sr 치(0.10~0.18)、Th/Nb 치(0.29~1.04)、Ba/La 치(17.61~23.92)등특정치,인위암장유각만혼합이성。종합전인연구성과,인위금구령조조면안산암형성우고태평양(이택내기)판괴사향부충아주대륙적활동륙연배경。
LA ICP MS zircon U Pb dating and geochemical data of the trachyandesite rocks from Jingouling Group in Yanbian region are obtained to figure out their formation time and the regional tectonic background .The zircons from the trachyandesite rocks are euhedral in shape with oscillatory ring displaying in CL images with high Th/U valwes 0 .43 0 .71(> 0 .40) .This implies their magmatic origin .The dating results indicate that these rocks formed in Early Cretaceous (130 ± 2 Ma ,MSWD =1 .8) .The composition of these rocks fall into the calc‐alkaline category with enrichment in LILE(such as K ,Ba ,Rb) ,LREE and more mobile incompatible elements ,such as Th , U ,relative depletion of HFSE(such as Ta ,Nb ,Ti ,P) .Combined with their high Mg # values (43 52) and Na2 O/K2 O = 1 .73 2 .25(> 1 .17) ,it shows the characteristics of the rocks from an active continental margin magma .Based on its Nb/Ta (14 .40 14 .72) ,Rb/Sr (0 .10 0 .18) ,Th/Nb (0 .29 1 .04) ,and Ba/La (17 .61 23 . 92) ,we conclude that the magma was a mixture of crust and mantle material .Together with the research of regional tectonics ,the corresponding geodynamic mechanisms responsible for the formation of the rocks may be closely related to the subduction of Paleo‐Pacific plate and Izanagi plate towards Eurasia continent .