磷灰石(U-Th)/He定年技术及应用简介  

Apatite (U-Th)/He dating and its application

作　　者：保增宽[1] 袁万明[1] 王世成[1] 汤云晖[1] 韩春明[1] 

机构地区：[1]中国科学院高能物理研究所

出　　处：《岩石矿物学杂志》2005年第2期126-132,共7页Acta Petrologica et Mineralogica

基　　金：国家自然科学基金资助项目 (4 0 0 72 0 68;10 175 0 76;10 475 0 93 ) ;国家重点基础研究发展规划项目 (2 0 0 1CB40 980 4)

摘　　要：本文阐述了磷灰石 (U_Th) /He定年技术的基本原理和方法、影响因素以及该技术在地质研究中的应用。磷灰石 (U_Th) /He定年是近年来发展起来的一种新型低温热年代学技术 ,能够给出地质体在 4 0～ 85℃低温范围内的独特信息。同裂变径迹定年技术一样 ,磷灰石 (U_Th) /He技术可用于年轻地质体的定年 ,也可确定时代较老的地质体最后一次热事件发生的时间。由于磷灰石 (U_Th) /He年龄数据与样品的海拔或埋藏深度密切相关 ,所以能够很好地约束古地形。结合其他同位素技术如裂变径迹定年技术等还可进行系统的热演化分析 ,如盆地的热史演化。与其他同位素定年技术相比 ,磷灰石 (U_Th) /He定年技术具有测量方便、精度高、所需样品数量少等优点。虽然这种技术目前尚处于不断完善之中 。This paper presents an overview of the fundamentals, techniques, influencing factors, and applications of the apatite (U-Th)/He dating method. (U-Th)/He dating of apatite is a newly developed low-temperature thermochronometry and has been gradually applied to different geological aspects, such as dating, tectonics, geological thermal history and paleotopography. The closure temperature of the apatite (U-Th)/He age is only about 75℃, which is lower than that of any other known technique, suggesting that apatite He age provides some information on the final stages of cooling. By combining apatite (U-Th)/He with other methods such as feldspar multidomain thermochronometry and fission track technique, more detailed and robust cooling histories may be obtained. Compared with other techniques, the attractions of the apatite He method lie in sensitivity to previously inaccessible temperature ranges, high precision and less sample mass. Although this technique remains at the developing stage, it may after all be accepted as a quite effective method for the low-temperature thermochronology. It is noted that this field is growing rapidly, and what is presented in this paper is likely to be superseded in the coming years.

关 键 词：定年方法 (U-Th)/He 低温热年代学 磷灰石 热历史 

分 类 号：P597.3[天文地球—地球化学] P578.922[天文地球—地质学]