摘要
华北地块中东部中生代侵入杂岩存在有富闪侵入岩和花岗闪长岩类两套岩石组合。对其中8个侵入杂岩体中的角闪石和黑云母进行了40Ar/39Ar定年研究。山西临汾塔儿山正长闪长斑岩、山西长治西安里岩体和河南安阳东冶岩体富闪侵入岩中角闪石的40Ar/39Ar坪年龄分别为(124.9±0.3)Ma,(127.7±0.3)Ma和(127.1±0.1)Ma;鲁西临朐铁寨正长闪长岩和枣庄流井花岗闪长斑岩中角闪石的40Ar/39Ar坪年龄均为(124.9±0.2)Ma;鲁西莱芜铁铜沟辉石闪长岩和蒙阴虎头崖花岗闪长斑岩中黑云母的40Ar/39Ar坪年龄分别为(132.8±0.3)Ma和(124.4±0.3)Ma;皖北管店花岗闪长斑岩中角闪石的40Ar/39Ar坪年龄为(126.9±0.2)Ma。上述结果显示华北地块中生代的岩浆活动主要发生在早白垩世。含有丰富幔源捕虏体的富闪侵入岩类和具有地壳成因的花岗闪长岩类岩石的共存,暗示早白垩世华北地块中生代岩石圈减薄达到了峰期。
Mesozoic intrusive complex in central eastern North China Block (NCB) is mainly composed of two sets of rock associations such as appinite and granodiorite. The 40Ar/39Ar dating of hornblendes and biotites from eight intrusives is made. The 40Ar/39Ar plateau ages of hornblendes from syenodiorite in Taershan intrusive, Linfen City, Shanxi Province, from appinites in Xianli intrusive, Changzhi City, Shanxi Province and in Dongye intrusive, Anyang City, Henan Province, are (124.9±0.3) Ma, (127.7±0.3) Ma and (127.1±0.1) Ma, respectively. The 40Ar/39Ar plateau ages of hornblendes both from syenodiorite in Tiezhai intrusive and from granodioritic porphyry in Liujing intrusive, western Shandong Province are (124.9±0.2) Ma. The 40Ar/39Ar plateau ages of biotites from pyroxene diorite in Tietonggou intrusive and from granodioritic porphyry in Hutouya intrusive, western Shandong are (132.8±0.3) Ma and (124.4±0.3) Ma, respectively. The 40Ar/39Ar plateau age of hornblende from granodiorite in Guandian intrusive, northern Anhui Province is (126.9±0.2) Ma. The mentioned above dating results imply that Mesozoic magmatism in the NCB chiefly happened in early Cretaceous. The coexistence of the mantle derived appinites and the crust derived granodiorites suggests that early Cretaceous magmatism is characterized by bimodal igneous rock association. It is proposed that the Mesozoic lithospheric thinning in the NCB could take place in early Cretaceous.
出处
《地球化学》
CAS
CSCD
北大核心
2004年第3期221-231,共11页
Geochimica
基金
国家自然科学基金(40172030
40133020)
中国石油化工股份有限公司"十五"重点科技攻关项目(P0000202)
关键词
中生代
侵入杂岩
AR-AR年代学
岩石圈减薄
华北地块
Mesozoic
intrusive complex
^(40)Ar/^(39)Ar dating
lithospheric thinning
the North China Block
