Limited Contribution of Preferential Dissolution to Radiogenic Uranium Isotope Disequilibrium Observed in Weathered Moraines  

作　　者：Laifeng Li Laura FRobinson Tianyu Chen Zhewen Xu Jun Chen Gaojun Li 

机构地区：[1]MOE Key Laboratory of Surficial Geochemistry,Department of Earth and Planetary Sciences,Nanjing University,Nanjing 210023,China [2]School of Geography and Ocean Science,Nanjing University,Nanjing 210023,China [3]School of Earth Sciences,University of Bristol,Bristol BS81RJ,UK [4]Frontiers Science Center for Critical Earth Material Cycling,Nanjing University,Nanjing 210023,China

出　　处：《Journal of Earth Science》2022年第1期57-66,共10页地球科学学刊（英文版）

基　　金：supported by the Royal Society-Newton Advanced Fellowship(No.NA201244);the Natural Science Foundation of China(Nos.42061130212,41991321,41877351,41761144058,and 41730101);the Second Tibetan Plateau Scientific Expedition and Research(STEP) Program(No.2019QZKK0707);the Fundamental Research Funds for the Central Universities(No.0206-14380124);support from the China Scholarship Council Fellowship。

摘　　要：Radiogenic uranium isotope disequilibrium(^(234)U/^(238)U) has been used to trace a variety of Earth surface processes,and is usually attributed to direct recoil of ^(234)Th and preferential dissolution of radioactively damaged lattices at the mineral surface.However,the relative contribution of these two mechanisms in the natural environment remains unresolved,making it hard to use the extent of disequilibrium to quantify processes such as weathering.This study tests the contribution of preferential dissolution using well-characterized weathered moraines and river sediments from the southeastern Tibetan Plateau.The observations show that weathering of recent moraines where the contribution from direct recoil is negligible and is not associated with depletion of ^(234)U at the mineral surface.It suggests a limited role for preferential dissolution in this setting.We attribute this lack of preferential dissolution to a near-to-equilibrium dissolution at the weathering interfaces,with little development of etch pits associated with radioactively damaged energetic sites.

关 键 词：preferential dissolution uranium isotope disequilibrium Gongga Mountain comminution comminution age etch pits 

分 类 号：P597[天文地球—地球化学]