摘要
用单颗粒锆石Ｕ－Ｐｂ稀释法获得的浙西南前寒武纪变质基底中花岗质岩石的年龄为：下际二长花岗岩１９７５±８０Ｍａ，里庄二长花岗岩１８７０±３６Ｍａ，田后花岗闪长岩１８３２±８０Ｍａ，三枝树混合岩１９６３±４４Ｍａ。这些年龄数据证实本区基底岩石在１８７５±１００Ｍａ时期经历了一次广泛强烈的岩浆热事件，表明八都群（麻源群）岩石的形成应早于２．０Ｇａ。三枝树地区“鹤溪群”中混合岩年龄为１８６３±４４Ｍａ，斜长角闪岩全岩矿物Ｓｍ－Ｎｄ等时线年龄为２０７１±４８Ｍａ，表明景宁三枝树地区变质岩的时代应为早元古代，并非原来所属“鹤溪群”划归的晚古生代，这套变质岩可能是浙闽变质基底的一部分。
U-Pb isotopic ages of four Early Proterozoic granitic bodies in southern Zhejiang have been determined:Xiaji admellite 1975±80Ma, Lizhuang adme- llite 1870±36Ma,Tianhuo granodiorite 1832±80Ma,and Sanzhishu migmatite 1863±44Ma,These data show that the rocks of the Zhejiang-Fujian Preca- mbrian metamorphic basement underwent an intense magmatic thermal event in the period of 1875±100Ma. This magmatic thermal event,which resulted in migmatization,granitization and magmatic intrusion in the basement rocks,played an important role in the formation of Zhejiang-Fujian stable crystalline basement.These results also suggest that the formation of the host rocks of the granitic rocks,namely Badu(Mayuan)Group,occured be- fore 2.0Ga. The 1863±44Ma U-Pb age of migmatite and 2071±48 Sm-Nd iso- chron age of amphibolite in Sanzhishu demonstrate that at least part of the“Hexi” Group is of Early Proterozoic rather than Late Paleozoic.The meta- morphic rocks in Sanshishu may be a part of Zhejiang-Fujian metamorphic basement.
出处
《岩石矿物学杂志》
CAS
CSCD
1995年第1期1-8,共8页
Acta Petrologica et Mineralogica
关键词
单锆石测年
花岗质岩石
花岗岩
年代
zircon U-Pb dating,granitic rocks,Zhejiaz1g-Fujian meta- morphic basement.Zhejiang Province
