二次离子质谱微区原位牙形石氧同位素分析及其在古海表水温记录中的应用  

In situ oxygen isotope analysis of conodonts by SIMS and its implication for paleo-sea surface temperature

作　　者：王润[1] 陈剑波[1] 赵来时[1] 陈泳霖[1] 唐国强[2] 李献华[2] 

机构地区：[1]中国地质大学地质过程与矿产资源国家重点实验室,武汉430074 [2]中国科学院地质与地球物理研究所岩石圈演化国家重点实验室,北京100029

出　　处：《世界地质》2013年第4期652-658,共7页World Geology

基　　金：国家自然科学基金(41272025);地质过程与矿产资源国家重点实验室科技部专项经费(MSFGPMR201110)联合资助

摘　　要：利用生物成因磷灰石的氧同位素信息能够重建古海水温度,尤其是牙形石,结合其在生物地层学上的研究,它的数据解释具有明确的古环境意义。牙形石微小的个体一直是其精确地球化学分析的限制因素。作为对牙形石微区原位氧同位素测试方法的探索研究,本文利用Cameca IMS--1280型二次离子质谱仪对牙形石进行了微区原位氧同位素组成测试,通过分析得到可靠的古表层海水温度(SST)记录,表明从晚二叠世到早三叠世SST存在明显的上升过程。相比常规Ag3PO4实验方法,牙形石微区原位氧同位素分析方法更加快速,而且能够有效避免牙形石易受到污染的部位,获得更为可靠的牙形石氧同位素组成的测定结果。Oxygen isotope composition of biogenic apatite, especially of the conodonts, is potentially useful in the reconstruction of contemporaneous surface seawater temperature （SST）. Combined with abundant researches on their biostratigraphy, the geochemical analysis of conodonts is more significant for indicating paleoenvironmental changes. However, the small size of conodont is always a factor limited for accurate analysis. In this work, the au- thors test the in situ oxygen isotope of conodont using Cameca IMS-1280 secondary ion mass spectrometry （SIMS） for the first time and acquire reliable records on contemporaneous SST. The results show that SST raised rapidly from Late Permian to Early Triassic. Compared with the AgaPO4method for popular use, this analysis is faster in carrying out with high resolution and high spatial resolution, and avoiding the contaminated position so as to acquire easily the reliable original oxygen isotopic compositions.

关 键 词：牙形石 氧同位素 微区原位分析 二次离子质谱 古温度 

分 类 号：Q913.2[天文地球—古生物学与地层学] P597.1[生物学—古生物学]