鲁东地区侵入岩形成时代和期次划分——锆石SHRIMP U-Pb年龄的证据

Study on Intrusive Rocks Forming Period and Stages Division in Ludong Area

鲁东地区前寒武纪侵入岩其侵入活动集中于新太古代和新元古代,均遭受不同程度的区域变质和韧性剪切带的改造,形成一套花岗质片麻岩类。新太古代早期TTG质花岗岩分布于胶北隆起区莱州—栖霞一带,经受了区域变质作用,形成一套灰色片麻岩,锆石内核SHRIMP U-Pb年龄2 726~2 707 Ma基本代表岩浆结晶年龄,锆石变质边为2500 Ma;古元古代侵入岩——莱州基性-超基性岩组合形成于1900~1850 Ma左右,锆石SHRIMP U-Pb年龄(1852±9)Ma,(1868±11)Ma;新元古代侵入岩主要为花岗闪长质—二长花岗质片麻岩,出露于胶南-威海造山带,锆石U-Pb定年结果集中为892~605 Ma,其中荣成超单元锆石SHRIMP U-Pb年龄720~780 Ma。中生代侵入岩以花岗岩类为主,集中出露于半岛北部和东南沿海一带。燕山早期侵入岩文登超单元、垛崮山超单元、玲珑超单元锆石SHRIMP U-Pb同位素年龄值集中在167~150 Ma;燕山晚期侵入岩大店超单元锆石SHRIMP U-Pb年龄120±4 Ma,崂山超单元锆石SHRIMP U-Pb同位素年龄值为(120±2)^(114±2)Ma。

Intrusive activities of early Precambrian intrusive rocks in Ludong area focused on new Archean and Proterozoic are all sufferred different degrees of regional metamorphism and ductile shear zone, and formed a series of granitic gneiss. TTG granitoids of new early Archean distributed in Laizhou - Qixia area of Jiaobei uplift, and experienced regional metamorphism and formed a set of gray gneiss. SHRIMP U - Pb age of zircon core is 2726 2707Ma, which basically represent magmatic crystallization age. The zircon metamorphic side is 2500Ma; Paleo- proterozoic intrusive rocks, that is Laizhou basic -ultrabasic rock combination were formed in about 1900 1850Ma. Its zircon SHRIMP U -Pb age is （1852 ±9）Ma, （1868 ± 11） Ma; Neoproterozoic intrusive rocks are mainly composed of granodioritic- monzonitic granitic gneiss, and exposed in Jiaonan -Weihai orogenic belt. Its zircon U - Pb dating results focus on 892 - 605 Ma. Mesozoic intrusive rocks are mainly composed of granitoid, and concentrated exposed in north part ofthe peninsula and southeast along the coast. Zircon SHRIMP U - Pb isotopic ages of intrusive rocks in early Yanshan period, such as Wendeng superunit, Duogushan superunit and Linglong superunit are 167 - 150Ma; while zircon SHRIMP U - Pb isotopic ages of Laoshan superunit in Yanshan intrusive rocks is （119.8 ±2.5） - （114.3 ± 1.9）Ma.