西太平洋帕劳砗磲高分辨率氧同位素记录及其指示的气候环境变化  

High-resolution oxygen isotope records of Tridacna gigas from Palau,Western Pacific and its climatic and environmental implications

作　　者：文汉锋 赵楠钰 刘成程[1,2] 周鹏超 王国桢 晏宏 WEN Hanfeng;ZHAO Nanyu;LIU Chengcheng;ZHOU Pengchao;WANG Guozhen;YAN Hong(State Key Laboratory of Loess and Quaternary Geology,Institute of Earth Environment,Chinese Academy of Sciences,Xi’an 710061,China;University of Chinese Academy of Sciences,Beijing 100049,China;Interdisciplinary Research Center of Earth Science Frontier(IRCESF),Beijing Normal University,Beijing 100875,China)

机构地区：[1]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,西安710061 [2]中国科学院大学,北京100049 [3]北京师范大学地球科学前沿交叉研究中心,北京100875

出　　处：《海洋地质与第四纪地质》2021年第1期1-13,共13页Marine Geology & Quaternary Geology

基　　金：国家自然科学基金“利用砗磲重建南海北部小时分辨率气候变化初探”(41877399),“地质新时代的人类世:时限、特征与影响”(41991250);中国科学院战略性先导科技专项B类(XDB40000000);中国科学院“西部之光”人才培养引进计划。

摘　　要：砗磲是海洋中最大的双壳类贝壳,其碳酸盐壳体通常具有年纹层和天纹层,是一种理想的高分辨率古气候研究载体。氧同位素是砗磲古气候研究中最常用的指标之一,但在将其应用于古气候重建之前,通常需要对其现代地球化学过程进行准确的校准。帕劳群岛位于西太平洋暖池西北边缘,其珊瑚礁盘具有丰富的砗磲壳体资源,为开展古气候研究提供了丰富的材料。在本次研究中,对采自帕劳群岛的现代活体库氏砗磲(Tridacna gigas)PL-1的内层壳体进行了高分辨率氧同位素分析,同时利用该砗磲较为清晰的天生长纹层对氧同位素的年代学框架进行了标定。结果表明,该砗磲壳体的氧同位素没有明显的变化趋势,说明砗磲个体的生命效应对氧同位素没有显著影响;砗磲壳体氧同位素没有清晰的年周期变化,常出现不规则的毛刺状峰值。结合现代器测资料分析发现,帕劳砗磲内层壳体的氧同位素记录了热带太平洋ENSO活动对该区域水文气候变化的影响。该研究结果表明,帕劳砗磲内层壳体天生长纹层和氧同位素,具有用于开展高分辨率古气候研究的潜力。Tridacna gigas is the largest marine bivalve,and its hard and dense aragonite shells usually have annual and daily growth lines,which have been demonstrated to be an ideal material for high-resolution paleoclimate research.The oxygen isotope has been widely used in Tridacna paleoclimate studies.However,the oxygen isotope of Tridacna shells must be accurately calibrated by modern geochemical process before paleoclimate reconstructions.Palau is located in the northwestern edge of the Western Pacific Warm Pool.Long-lived Tridacna spp.is a common species in the coral reefs of Palau Islands,which may provide abundant materials for paleoclimate reconstructions.In this study,we present a high-resolution oxygen isotope profile from the inner shell of a modern living T.gigas specimen PL-1 from Palau.The high-resolution chronology of the oxygen isotope profile is determined by the clear daily growth layers in the inner shell.The result suggests that theδ18Oc profile of the T.gigas shell has no obvious trend,indicating that the vital effects have no significant influence on the oxygen isotope of shell.Combining with the instrumental data,we found that the ENSO activities in the tropical Pacific had impacts on the regional hydro-climate changes of Palau,and left some fingerprint in the oxygen isotope of Tridacna shell.This study indicates that the daily growth layer and the oxygen isotope in the inner shell of Tridacna from Palau have the potential for high-resolution paleoclimate research.

关 键 词：砗磲 天生长纹层 氧同位素 ENSO 

分 类 号：P532[天文地球—古生物学与地层学] P736.4[天文地球—地质学]