摘要
岩石中的自然热释光强度是辐射诱发的热释光生长与衰退共同作用的结果。热释光的衰退包括热衰退和异常衰退两部分,其中,热衰退与温度有关。在岩石从地下向地表剥露过程中,随温度的降低热衰退减小,从而使岩石中的自然热释光强度增强,利用此现象可从热释光中得到岩石的冷却历史。钾长石热释光的封闭温度为40 ℃~80 ℃,低于其他低温热年代学方法的封闭温度,因此钾长石热释光热年代学方法能约束浅地表的剥露。同时,由于该方法具有更短的时间尺度和更高的精度,可精确描述剥露速率随时间的变化关系,因此可更好地揭示构造、侵蚀、气候三者间的关系,尤其是揭示第四纪以来这三者间的关系。最后,介绍了钾长石热释光热年代学在东喜马拉雅构造结以北中的应用,证实100 ka以来东构造结以北存在快速剥露,其可能是构造结向北扩张的结果。
Thermoluminescence thermochronometry of K-feldspar can be used as a new thermochronometer to constrain exhumation history of rocks over short-term timescale.This theory is based on that natural thermoluminescence level in buried rocks is a dynamic equilibrium between radiation-induced thermoluminescence growth and decay.There are two kinds of decay modes in thermoluminescence:thermal decay and athermal decay.The thermal decay is temperature-dependent and proportional to ambient temperature.The thermal decay decreases with geotherm decreasing when rocks exhume from deep in the crust to the surface,leading to the increase of thermoluminescence level in rocks.This phenomenon can be analyzed and used to constrain the cooling history of rocks.Lock temperature of this new method which is related to closure temperature of thermochronometry is between 40℃-80℃.Due to its low closure temperature,it can be used to constrain exhumation near the earth surface.Meanwhile,this method also has high resolution to constrain exhumation history over short timescale,thus it can be used to investigate the relationship among tectonic,erosion and climate,especially,in the quaternary.This paper introduces the application of this new method in the eastern Himalaya syntaxis.The results show that there is a period of rapid exhumation since 100 ka to the north of the syntaxis which may be caused by the northward expansion of the syntaxis.
作者
刘婷
杨蓉
LIU Ting;YANG Rong(School of Earth Sciences,Zhejiang University,Hangzhou 310027,China)
出处
《浙江大学学报（理学版）》
CAS
CSCD
北大核心
2021年第3期338-348,390,共12页
Journal of Zhejiang University（Science Edition）
基金
国家自然科学基金资助项目(41602210).
关键词
钾长石热释光热年代学
剥露历史
东喜马拉雅构造结
thermoluminescence thermochronometry of K-feldspar
exhumation history
eastern Himalayan syntaxis
