鲁东地区侵入岩形成时代和期次划分

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

摘要:

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。

Abstract:

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; Paleoproterozoic 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 892~605Ma. 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.