摘要
碎屑锆石U-Pb年代学分析被广泛应用于限定地层沉积时代、重建沉积物源和古地理格局,结合Lu-Hf-O同位素的分析可以进一步制约地壳生长演化历史。锆石在地表过程中具有极强的稳定性,沉积再循环的碎屑锆石长期以来被认为广泛存在于各类碎屑沉积岩中,对碎屑锆石的数据解读产生重要影响,但是目前还没有简单直接的方式进行有效识别。本文对沉积再循环作用和再循环碎屑锆石判别手段的原理和相关地质应用做了简要总结,包括碎屑矿物结构、岩石化学成分、锆石多同位素年代学分析、多种碎屑副矿物联合示踪和放射性损伤评估等方法,评述了不同方法的优劣和适用条件。本文以长江流域的碎屑物源研究为例,使用源归一化的辐射剂量(α-dose)评估流域内再循环碎屑锆石的存在及其对物源重建的意义。我们强调基于碎屑锆石的研究应该综合区域的沉积记录和岩浆构造历史,考虑沉积再循环作用对数据解读的可能影响,为碎屑锆石数据赋予更加合理的地质解释。
The U-Pb geochronology analysis of detrital zircons is widely used to constrain the deposit age of strata and reconstruct sediment sources and paleogeographic evolution.Combined with the analysis of Lu-Hf-O isotopes,it can further constrain the history of crustal growth and evolution.Sedimentary recycled detrital zircon is widely present in various types of clastic sedimentary rocks due to its high resistance to surface processes,which has long been considered to bear a significant impact on the interpretation of detrital zircon data.However,there is currently hardly any efficient way to identify sedimentary recycled detrital zircon.This study provides a summary of the principles and related geological applications of sedimentary recy-cling and the discrimination methods for recycled detrital zircons,including means such as detrital mineral structure,rock chemical composition,multi-isotope geochronology analysis on zircons,multiple detrital mineral analysis,and radioactive damage assessment.The advantages and disadvantages of different methods and their applicable conditions have been evaluated.This article presented a case study on zircon provenance in the Yangtze River,using source-normalized radiationα-dose to assess the presence of recycled detrital zircons.We emphasize that research based on detrital zircon should integrate regional sedimentary records and magmatic-tectonic history to provide more reliable geological interpretations for detrital zircon data,considering the potential impact of sedimentary recycling on data interpretation.
作者
宋仁龙
秦拯纬
周光颜
鲍波
SONG Ren-Long;QIN Zheng-Wei;ZHOU Guang-Yan;BAO Bo(China University of Geosciences,Wuhan 430074,Hubei,China;Wuhan Center of China Geological Survey(Geosciences Innovation Center of Central South China),Wuhan 430205,Hubei,China;Research Center for Petrogenesis and Mineralization of Granitoid Rocks,China Geological Survey,Wuhan 430205,Hubei,China)
出处
《华南地质》
CAS
2024年第1期1-27,共27页
South China Geology
基金
中国地质调查局地质调查项目(DD20243429、DD20221689)
中国地质调查局花岗岩成岩成矿地质研究中心开放基金课题(PMGR202111)。
关键词
碎屑锆石
沉积再循环
岩浆构造历史
物源
长江流域
detrital zircon
sedimentary recycling
magmatic-tectonic history
material sources
Yangtze riv�er basin
