有机质激光拉曼光谱温度计应用——以鄂西灯影组为例  

Application of organic matter laser Raman spectroscopy thermometry:A case study of Dengying Formation in Western Hubei

作　　者：肖倩 牛岩 范小军 何宏伟 佘振兵[3] 夏志诚 Xiao Qian;Niu Yan;Fan Xiaojun;He Hongwei;She Zhenbing;Xia Zhicheng(Western Hubei Geological Design Co.,Ltd,Yichang,Hubei 443100;Seventh Geological Brigade of Hubei Geological Bureau,Yichang,Hubei 443100;China University of Geosciences,Wuhan,Hubei 430074)

机构地区：[1]湖北鄂西地质设计有限公司,湖北宜昌443100 [2]湖北省地质局第七地质大队,湖北宜昌443100 [3]中国地质大学(武汉),湖北武汉430074

出　　处：《资源环境与工程》2024年第5期486-495,共10页Resources Environment & Engineering

摘　　要：激光拉曼光谱测试是一种快速、简便且对样品无损的分析方法,在评估深时地质样品中碳质物热演化历史方面具有显著优势,但在其使用过程中还存在较大的争议。以鄂西地区灯影组碳酸盐岩为研究对象,通过批量激光拉曼光谱测试,计算获得平均拉曼温度为201~226℃,该温度变化在可接受的范围内。灯影组白马沱段与蛤蟆井段白云岩拉曼温度偏高且较为稳定,而石板滩段灰岩单个样品拉曼温度范围较广(180~230℃),在不同有机质富集程度下拉曼光谱特征差异大,垂向上温度波动也较为明显,I_(1350)/I_(1600)值(0.5~1.5)在石板滩段也呈现相似的分布特征,但其与有机碳同位素比值(δ^(13)C_(org))、总有机碳(TOC)含量之间不存在相关性。结果表明,有机质激光拉曼光谱(RSCM)温度计在评估深时地质样品埋藏变质温度具有较大潜力,在使用时应以同一盆地中最高变质温度为准,并增大单个样品中数据采集点数以减少误差;灯影组有机质拉曼温度不均一性是由于不同有机质富集程度的不均匀热演化程度导致的,其总体上处于极低级埋藏变质温度条件,有利于埃迪卡拉后生动物化石的保存。Raman spectroscopy is a rapid,simple,and non-destructive analytical method that has significant advantages in assessing the thermal evolution history of carbonaceous materials in deep-time geological samples.However,its usage remains controversial and disputed.This study,taking the Dengying Formation carbonates in western Hubei region as an example,conducted batch Raman spectroscopy tests and calculated the average temperature to be 201℃to 226℃.This temperature variation falls within an acceptable range.The Raman temperatures of dolomite in the Baimatuo and Hamajing Members are relatively high and stable,whereas the Ramen temperature range within individual limestone samples from the Shibantan Member is large(180-230℃).The Raman spectral characteristics vary significantly with different degrees of organic matter enrichment,and the temperature fluctuations are also evident vertically.The I_(1350)/I_(1600) ratio(0.5-1.5)in Shibantan memeber exhibits a similar distribution pattern,but there is no correlation with organic carbon isotope ratios(δ^(13)C_(org))and total organic carbon(TOC).These results indicate that the organic matter Raman thermometer has substantial potential for evaluating the burial metamorphic temperature of deep-time samples.When employing this method,the highest metamorphic temperature should be considered in the same basin,and increasing the number of sampling points within a single sample can reduce errors.The heterogeneity in the Raman temperatures of organic matter in the Dengying Formation is due to uneven metamorphism related to varying degrees of organic matter enrichment.The Dengying Formation is under ultra-low-grade burial metamorphic temperature conditions,which is conducive to the preservation of Ediacaran metazoan fossils.

关 键 词：拉曼光谱温度计 灯影组 埋藏变质温度 有机质富集程度 热演化程度 鄂西地区 

分 类 号：P575.4[天文地球—矿物学]