大别山东端郯庐断裂带由走滑向伸展运动转换的^(40)Ar-^(39)Ar年代学记录  

^(40)Ar-^(39)Ar GEOCHRONOLOGY RECORDS OF TRANSITION FROM STRIKE-SLIP TO EXTENSION IN THE TAN-LU FAULT ZONE ON EASTERN TERMINAL OF THE DABIE MOUNTAINS

作　　者：王勇生[1] 朱光[1] 宋传中[1] 刘国生[1] 向必伟[1] 李长城[1] 谢成龙[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242-255,共14页Chinese Journal of Geology(Scientia Geologica Sinica)

基　　金：国家自然科学基金资助项目(批准号:40272094)。

摘　　要：通过对大别山东端郯庐左旋韧性剪切带中一系列含白云母、黑云母、斜长石和钾长石的糜棱岩样品40Ar-39Ar同位素年代学研究,发现大别山东端的郯庐断裂带在距今139Ma之前发生过一次左行平移运动,随后转变为伸展活动,由走滑向伸展活动转换的时间介于距今139Ma至128Ma之间。在伸展活动中,大别山东端的郯庐走滑韧性剪切带发生了缓慢的抬升和冷却,从而导致封闭温度较低的矿物记录了较小的年龄。黑云母110Ma±以及斜长石97~92Ma的40Ar-39Ar年龄值指示郯庐断裂带的伸展活动一直持续到距今90Ma±。So far there is a dispute on active modes and time of the Tan-Lu fault zone. This paper used 40Ar-39Ar geochronology to study the samples of muscovite, biotite, plagioclase or K-feldspar from the mylonites along the sinistral Tan-Lu ductile shear zone on eastern terminal of the Dabie Mountains. It was discovered that the Tan-Lu fault zone acted as a sinistral strike-slip one before 139 Ma, then became an extensional one. Our work revealed that the transition time might be 128 - 139 Ma ago. In the course of extension, the Tan-Lu ductile shear zone experienced slowly rift and cooling, which caused the minerals with less closure temperature recorded small ages. The 40Ar-39Ar ages of 110 Ma of the biotite and 97 -92 Ma of the plagioclase indicated that the extension activity of the Tan-Lu fault zone continued to about 90 Ma.

关 键 词：40Ar-396Ar年龄 走滑向伸展的转换 郯庐断裂带 大别山东端 早白垩世 

分 类 号：P597[天文地球—地球化学]