摘要
鲁西中生代侵入岩包括辉长岩,闪长岩,花岗闪长岩和花岗岩,以闪长岩最为常见。莱芜和沂南等地的闪长岩具有高Mg#(0.45～0.69),Cr(<278μg/g)的特点,并富集大离子亲石元素(LILE)和亏损高场强元素(HFSE),其总体成分特点类似于北美苏必利尔省的太古代高镁闪长岩和产于现代俯冲带的高镁安山岩。不过鲁西高镁闪长岩的HREE含量相对较高(Yb=1.1～1.9μg/g),La/Yb比值相对较低(6.7～20),其成分更接近于Piip型高镁安山岩。鲁西高镁闪长岩代表了华北地台早期拉张环境下的岩浆活动,可能是受深俯冲扬子大陆下地壳释放的埃达克质熔体交代的岩石圈地幔直接熔融的产物。
The Mesozoic intrusives in western S handong include gabbros,diorites,granodiorites and granites with diorites being dominant.The diorites from Laiwu and Yinan have high Mg # (0.45～0.69)and Cr contents(up to278μg /g),and are rich in large ion lithophile elements(LILE)and depleted in high strength field e lements(HFSE).They compositionally resemble the late Archaean high-Mg diorites from Superior Province in North America and magnesian andesites in modern subduction zones.Specifically,the relatively high HREE(Yb =1.1～1.9μg /g)contents and low La /Yb ratios(6.7～20)in the high-Mg diorites from western Shandong show their close affinity to the Piip-typ e magnesian andesites.It is propose d that the high-Mg diorites from western Shandong marked the early phases of m agmatism in a continental extension al setting.Their petrogenesis is pr obably related to partial melting of the lithospheric mantle that is metasomati zed by adakitic melts derived from su bducted Yangtze continental crust under the North China Craton.
出处
《大地构造与成矿学》
EI
CAS
CSCD
北大核心
2003年第3期228-236,共9页
Geotectonica et Metallogenia
基金
国家杰出青年基金项目(编号:49925308)资助.
关键词
中生代
高镁闪长岩
岩石圈地幔
华北地台
Mesozoic
high-Mg diorite
lithosp heric mantle
North China Craton
