华南地质与矿产
華南地質與礦產
화남지질여광산
GEOLOGY AND MINERAL RESOURCES OF SOUTH CHINA
2012年
2期
124-131
,共8页
TTG片麻岩%基性岩脉%锆石U-Pb年龄%Hf同位素%黄陵地区
TTG片痳巖%基性巖脈%鋯石U-Pb年齡%Hf同位素%黃陵地區
TTG편마암%기성암맥%고석U-Pb년령%Hf동위소%황릉지구
TTG gneiss%mafic dike%zircon U-Pb age%Hf isotope%Huangling area
采用激光剥蚀-等离子质谱（LA-ICP-MS）分析技术测定野马洞基性岩脉中锆石的U-Pb年龄和Hf同位素组成,以探讨黄陵地区TTG片麻岩原岩的形成及变质时间、是否存在比崆岭群更古老的地壳等问题。野马洞辉绿岩脉（1850 Ma）侵入TTG片麻岩,并从TTG片麻岩中捕获了大量捕掳晶锆石。捕掳晶锆石岩浆结晶核部的U-Pb年龄分别为2842 Ma、2900 Ma和2949 Ma,指示TTG花岗岩体为复式岩体,其至少经历了2949 Ma、2900 Ma和2842 Ma三期岩浆作用。捕掳晶锆石变质边部的U-Pb年龄为2557 Ma,指示TTG花岗岩体转变为TTG片麻岩,是＂水月寺运动＂及其构造热事件共同作用的结果,其变形变质的时间为2557～2511 Ma。捕掳晶锆石的εHf（t）为-9.85～0.89、平均值为-4.07,亏损地幔模式年龄TDM为3.6～3.2 Ga,指示黄陵地区存在比崆岭群（3.2 Ga）更古老的陆壳。
採用激光剝蝕-等離子質譜（LA-ICP-MS）分析技術測定野馬洞基性巖脈中鋯石的U-Pb年齡和Hf同位素組成,以探討黃陵地區TTG片痳巖原巖的形成及變質時間、是否存在比崆嶺群更古老的地殼等問題。野馬洞輝綠巖脈（1850 Ma）侵入TTG片痳巖,併從TTG片痳巖中捕穫瞭大量捕擄晶鋯石。捕擄晶鋯石巖漿結晶覈部的U-Pb年齡分彆為2842 Ma、2900 Ma和2949 Ma,指示TTG花崗巖體為複式巖體,其至少經歷瞭2949 Ma、2900 Ma和2842 Ma三期巖漿作用。捕擄晶鋯石變質邊部的U-Pb年齡為2557 Ma,指示TTG花崗巖體轉變為TTG片痳巖,是＂水月寺運動＂及其構造熱事件共同作用的結果,其變形變質的時間為2557～2511 Ma。捕擄晶鋯石的εHf（t）為-9.85～0.89、平均值為-4.07,虧損地幔模式年齡TDM為3.6～3.2 Ga,指示黃陵地區存在比崆嶺群（3.2 Ga）更古老的陸殼。
채용격광박식-등리자질보（LA-ICP-MS）분석기술측정야마동기성암맥중고석적U-Pb년령화Hf동위소조성,이탐토황릉지구TTG편마암원암적형성급변질시간、시부존재비공령군경고로적지각등문제。야마동휘록암맥（1850 Ma）침입TTG편마암,병종TTG편마암중포획료대량포로정고석。포로정고석암장결정핵부적U-Pb년령분별위2842 Ma、2900 Ma화2949 Ma,지시TTG화강암체위복식암체,기지소경력료2949 Ma、2900 Ma화2842 Ma삼기암장작용。포로정고석변질변부적U-Pb년령위2557 Ma,지시TTG화강암체전변위TTG편마암,시＂수월사운동＂급기구조열사건공동작용적결과,기변형변질적시간위2557～2511 Ma。포로정고석적εHf（t）위-9.85～0.89、평균치위-4.07,우손지만모식년령TDM위3.6～3.2 Ga,지시황릉지구존재비공령군（3.2 Ga）경고로적륙각。
By LA-ICP-MS methods,the U-Pb dating and Lu-Hf isotopic analysis were carried out for zircons from Yemadong mafic dikes in Huangling area,we can ascertain the forming and metamorphic age of TTG granites,and discuss whether there were some crustal remnants older than Kongling Group in the Huangling area.The Yemadong doleritic dikes intruded in the TTG gneisses,and captured many xenocrystic zircons from the country rocks.The xenocrystic zircons show the core-rim structure,the cores have magmatic oscillatory zoning,and the rims are not zoning,The thirty individual U-Pb spot analyses were done on magmatic cores of 30 xenocrystic zircon grains,and yielded three ages of 2949 Ma,2900 Ma and 2842 Ma,these indicate that the TTG granites is a complex intrusive which experiencing at least three stages of magmatism including 2949 Ma,2900 Ma and 2842 Ma.One U-Pb spot analysis was done on metamorphic rim of zircon grain,and yielded a concordant age of 2557 Ma,which is responsible for the timing of metamorphism.This provides the first demonstration for the occurrence of tectono-thermal event at about 2557 Ma,which has been connected to the Shuiyuesi movement.In the same time,the TTG granite has been metamorphism into the TTG gneisses during the tectono-thermal event resulted from the Shuiyuesi movement in the Huangling area.The xenocrystic zircons have the negative εHf（t） values of-9.85～0.89 with the average values of-4.07,and the Hf model age of 3.6～3.2 Ga,these reveals the existence of old crustal relicts with the age of 3.6～3.2 Ga rocks,which is older than the Kongling Group（3.2 Ga） in Huangling area.
