摘要
同位素地球化学被广泛用于岩石年代学和源区示踪。但是在地壳深熔过程中,地壳岩石的熔融温度一般较低,且壳内岩石的熔融通常伴有强烈的构造变形,加速了熔体提取,使得熔融过程中产生的熔体和残留体之间的同位素较难达到均一化。因此,开展地壳岩石深熔过程中同位素组成变化的研究,评估地壳深熔过程中熔体与残留体和原岩间同位素组成是否达到平衡,对于我们利用同位素进行地球化学示踪十分关键。在地壳深熔过程中,影响同位素不平衡的因素较多,包括变质深熔的温度压力条件、熔融方式、不同矿物的分解和贡献以及源区不均一性等。然而,这些同位素不平衡最终可能是在一定的温压条件下,不同的矿物或熔流体参与熔融反应所引起的。因此,考察地壳深熔过程中不同矿物的行为至关重要,包括矿物的化学组成、矿物的母体与子体同位素(或轻重金属稳定同位素)的元素含量和同位素比值、矿物在不同温压条件下的稳定性以及参与熔融反应的矿物比例等。
Isotope geochemistry is widely used in petrochronology and source tracing.However,during crustal anatexis,melting temperatures are typically lower than those required for mantle melting.Furthermore,partial melting of crustal rocks is often accompanied by intense structural deformation,facilitating the extraction of anatectic melts.This hinders the achievement of isotopic equilibrium between the anatectic melt and its residual source.Consequently,investigating isotopic composition changes during the partial melting of deeply subducted crustal rocks is crucial for assessing whether isotopic equilibrium is attained among the melt,residue,and protolith.Such assessment is essential for the reliable application of isotopes in geochemical tracing.Multiple factors influence isotopic variations during crustal anatexis,including the P-T conditions of metamorphism and melting process,melting modes,the decomposition and contribution of constituent minerals,and source heterogeneity.Ultimately,the isotope disequilibrium arising from these diverse factors stems from the distinct participating of specific minerals or melts/fluids in melting reaction under certain P-T conditions.Therefore,it is crucial to investigate the behavior of different minerals during crustal anatexis,including the mineral chemistry,the contents and ratios of parent and daughter isotopes(or heavy and light metal isotopes)in minerals,the stability of minerals under different P-T conditions,as well as the proportion of minerals involved in the melting reaction,etc.
作者
夏琼霞
朱二林
束浩鸿
陈仁旭
XIA QiongXia;ZHU ErLin;SHU HaoHong;CHEN RenXu(School of Earth and Space Sciences,University of Science and Technology of China,Hefei 230026,China;State Key Laboratory of Lithospheric and Environmental Coevolution,University of Science and Technology of China,Hefei 230026,China)
出处
《岩石学报》
北大核心
2025年第9期3180-3189,共10页
Acta Petrologica Sinica
基金
国家自然科学基金项目(42472069、92155306)资助.
