张八岭地区中生代岩体中黑云母的^(40)Ar-^(39)Ar年龄及其地质意义  

^(40)Ar-^(39)Ar DATING OF BIOTITE FROM THE MESOZOIC INTRUSIONS IN ZHANGBALING AREA AND ITS GEOLOGICAL SIGNIFICANCE

作　　者：牛漫兰[1] 

机构地区：[1]合肥工业大学资源与环境工程学院,合肥230009

出　　处：《地质科学》2006年第2期217-225,共9页Chinese Journal of Geology(Scientia Geologica Sinica)

基　　金：国家自然科学基金项目(批准号:40272094)的部分成果。

摘　　要：张八岭地区顺郯庐断裂带由北向南出露了管店、瓦屋刘和瓦屋薛3个岩体,岩性分别为花岗闪长岩、石英二长岩和花岗岩。对其中两个侵入岩体中黑云母进行了40Ar-39Ar定年研究。张八岭隆起北段瓦屋刘石英二长岩和瓦屋薛花岗岩中黑云母的40Ar-39Ar坪年龄分别为127.84±0.77Ma和119.97±0.64Ma,表明岩浆活动主要发生在早白垩世中期。结合最近断裂带内走滑糜棱岩中角闪石143.3±1.3Ma的40Ar-39Ar年龄,暗示了早白垩世中期断裂带内出现岩浆活动时,郯庐断裂带已转变成正断层活动,而不是以往认为由断裂带走滑诱发的岩浆活动,与华北地块东部岩石圈减薄的峰期时间基本一致。Three extended intrusions, in southward order, the Guandian granodiorite, the Wawuliu quartz monzonite and the Wawuxue granite occurred in Zhangbaling area, Anhui, along the Tan-Lu fault zone. The 40Ar-39Ar dating of biotites from the latter two intrusions was made. The 40Ar-39Ar plateau ages of biotites from the Wawuliu quartz monzonite and Wawuxue granite yielded 127.84±0.77 Ma and 119.97 ± 0.64 Ma, respectively. The mentioned above dating resuits implied that the Mesozoic magmatism in the northern segment of the Zhangbaling Rise along the Tan-Lu fault zone mainly occurred in the middle period of Early Cretaceous. Combined with 40Ar-39Ar ages （ 143.3 ± 1.3 Ma） of the homblendes from the mylonites of the TanLu fault zone, it suggested that the Tan-Lu fault zone had turned into extensional movement at the middle period of Early Cretaceous, and the magmatic activities might not be induced by strike-slipping of the Tan-Lu fault zone, which was coincident with lithospheric thinning peak time in eastern North China Block.

关 键 词：AR-AR年代学 岩石圈减薄 郯庐断裂带 中生代侵入岩 

分 类 号：P597[天文地球—地球化学]