沉积再循环碎屑锆石的地质意义及其识别——以长江流域的碎屑物源研究为例
Geological Significance of the Sedimentary Recy-cling Detrital Zircon and Its Recognition:Taking Source Study of Clastic Rocks in the Yang-tze River Basin as an Example
宋仁龙 1秦拯纬 2周光颜 1鲍波2
作者信息
- 1. 中国地质大学(武汉),湖北武汉 430074
- 2. 中国地质调查局武汉地质调查中心(中南地质科技创新中心),湖北武汉 430205;中国地质调查局花岗岩成岩成矿地质研究中心,湖北武汉 430205
- 折叠
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.
Abstract
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 sur-face 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 zir-con.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 min-eral 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 radiation α-dose to assess the presence of recycled detrital zir-cons.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,consider-ing the potential impact of sedimentary recycling on data interpretation.
关键词
碎屑锆石/沉积再循环/岩浆构造历史/物源/长江流域Key words
detrital zircon/sedimentary recycling/magmatic-tectonic history/material sources/Yangtze riv-er basin引用本文复制引用
基金项目
中国地调局地质调查项目(DD20243429)
中国地调局地质调查项目(DD20221689)
中国地调局花岗岩成岩成矿地质研究中心开放基金(PMGR202111)
出版年
2024
国家科技期刊平台
NSTL
万方数据