南海珊瑚高精度热电离质谱和多接收电感耦合等离子体质谱铀系年龄和古环境意义  

High-precision timing of Nanhai coral by using MC-ICP-MS and TIMS techniques and its paleo-environmental significance

作　　者：彭子成[1,2] 贺剑峰[1] 罗晓忠[3] 刘桂建[1] 聂宝符[4] 陈特固[4] 

机构地区：[1]中国科学技术大学地球和空间科学学院 [2]中国科学院地球环境研究所黄土与第四纪地质国家实验室西安710054 [3]美国密歇根大学地質科学系 [4]中国科学院南海海洋研究所

出　　处：《核技术》2004年第6期469-474,共6页Nuclear Techniques

基　　金：中国科学院知识创新工程项目(KZCX2-SW-118;KZCX3-SW-120);国家科技部基础研究重大项目(2001CCB00100);国家自然科学基金项目(No.40176031);中国科学院地球环境研究所黄土与第四纪地质国家重点实验室开放基金项目(SKLLQG0324)资助

摘　　要：阐明了热电离质谱(TIMS)和多接收电感耦合等离子体质谱(MC-ICP-MS)技术进行铀系定年和示踪研究的特点。从实测国内石笋标样(GBW04412)和国际珊瑚标样(RKM-4)的结果表明;;其铀含量U/238U234和Th/234U比值;;以及铀系年龄均与标准值一致。应用该两种技术;;对采自雷州半岛、海南岛和西沙永兴岛230海域的珊瑚测定表明;;其铀含量大多低于3μg/g;;且δ234U(T)值处于150±5范围。这显示了所测定的南海珊瑚距今7000年以来保持着封闭体系;;其骨骼中赋存了原始的热带海洋环境信息。由所测得珊瑚的高精度年龄序列可以揭示南海海域曾出现过的三次高海平面;;分别为距今6799—6307年;;距今4472—4285年和距今1279—1012年。此三阶段与近万年以来中国曾出现过的全新世大暖期和中世纪暖期的热环境相映。The techniques of thermal ionization mass spectrometry (TIMS) and multicollector-inductively coupled plasma-mass spectrometry (MC-ICP-MS) were used for the high-precision timing of the domestic stalagmite standard (GBW04412), international coral standard (RKM-4) and the Nanhai corals. The results of uranium contents and the ratios of234U/238U and 230Th/234U in the two standards measured by using two techniques were consistent within the error range. Most of the Nanhai corals have less than 3 μg /g of the uranium contents and 150±5 of the δ234U(T) values, which means that the corals have not been subjected to the alternation since they were brought up 7000 years ago, therefore, they preserve the original environmental signals. The age sequence of the corals shows that three events of the high sea level happened in Nanhai area in the periods corresponding to 6799-6307 a B.P., 4472-4285 a B.P. and 1279-1012 a B.P. respectively. The above-mentioned three stages were relative to the Megathermal and Medieval Warm Periods in our country.

关 键 词：南海珊瑚 热电离质谱 多接收电感耦合等离子体质谱 铀系年龄 古环境意义 

分 类 号：P597.1[天文地球—地球化学] O657.63[天文地球—地质学]