基于碎屑锆石裂变径迹记录的下扬子构造热演化史研究  

Thermotectonic evolution history of the lower Yangtze area based on detrital zircon fission-track analysis

作　　者：王丹萍[1] 许长海[1] 焦若鸿[1] 周祖翼[1] 

机构地区：[1]同济大学海洋地质国家重点实验室,上海200092

出　　处：《中国矿业大学学报》2011年第2期227-234,共8页Journal of China University of Mining & Technology

基　　金：国家自然科学基金项目(40872138)

摘　　要：为了揭示下扬子南部露头区中、古生界地层的构造热演化特点及其控制环境,本文应用刻画温度与时间关系较好的锆石裂变径迹技术(ZFT),对苏皖下扬子15个中、古生界碎屑岩进行热演化分析.研究结果表明:中、古生界碎屑岩表现出214～75Ma的ZFT年龄特点,这些ZFT年龄及其颗粒年龄的变化,主要与后期差异热改造以及不同碎屑锆石的裂变径迹抵制退火的难易程度不同有关.这些碎屑岩ZFT年龄的一个显著特点是集中在157～95Ma,这一时限与下扬子乃至中国东部160～100Ma时期广泛的岩浆活动时间是一致的,可见岩浆热改造对于碎屑岩ZFT热年龄的影响是至关重要的.2个南华系碎屑岩(ZFT10和ZFT11)的ZFT测年结果(76～75Ma)与NW-SE向的区域构造带活动或者是断裂活动有关.It is difficult to acquire a corresponding relationship between temperature and time using reflectance of vitrinite as a major geothermometer.In order to reveal characteristics of the tectono-thermal evolution of the outcrops of south Lower Yangtze area and its regional controls,detailed zircon fission track analysis（ZFT）,which can depict a good corresponding relationship between temperature and time,on fifteen Palaeo-Mesozoic clastic rocks was carried out.The results show that the Palaeo-Mesozoic clastic rocks have zircon fission-track ages ranging from 214 to 75 Ma.These ZFT ages（pooled ages or central ages） coupled with ZFT grain ages show characteristics of regional thermal variation,corresponding to the difference of tectonothermal reconstruction and differential ZFT annealing properties.The ZFT ages dominantly concentrate on the period of 157 to 95 Ma,as a magnificent feature,according with the time of 160-100 Ma for large-scaled magmatism that ocurred in the Lower Yangtze and Southeast China.It follows that this magmatism is considered to exert appreciable influence upon sample ZFT thermochronology.Two younger ZFT results（ZFT10 and ZFT11） of 75 and 76 Ma from the Nanhua Series are associated with faulting of the NW-SE structural zone.

关 键 词：锆石裂变径迹 中、古生界 碎屑岩 热改造 

分 类 号：P579[天文地球—矿物学]