氧同位素在古温度重建及水循环研究中的应用  

Oxygen isotope application in paleotemperature reconstruction and water cycle in the deep time

作　　者：陈波[1] 朱茂炎[1,2] Bo Chen;Maoyan Zhu(State Key Laboratory of Palaeobiology and Stratigraphy,Center for Excellence in Life and Paleoenvironment,Nanjing Institute of Geology and Palaeontology,Chinese Academy of Sciences,Nanjing 210008,China;College of Earth and Planetary Sciences,University of Chinese Academy of Sciences,Beijing 100049,China)

机构地区：[1]中国科学院南京地质古生物研究所,生物演化与环境卓越中心,现代古生物学和地层学国家重点实验室,南京210008 [2]中国科学院大学地球与行星科学学院,北京100049

出　　处：《科学通报》2023年第12期1528-1543,共16页Chinese Science Bulletin

基　　金：国家重点研发计划(2022YFF0800100);中国科学院战略性先导科技专项(B类)(XDB26000000);国家自然科学基金(42272025,41921002)资助。

摘　　要：适宜的温度是宜居地球最基本的要素之一.地质历史时期海水温度演变规律成为揭示地球气候变化和生物演化的关键环境参数.目前,恢复深时古海水温度最常用的技术手段是碳酸盐和磷酸盐矿物化石骨骼的氧同位素组成.但该方法面临成岩蚀变、化石属种的生命效应、区域性海水氧同位素组成差异、海水氧同位素组成是否随时间发生变化等诸多不确定性因素的影响.本文在回顾深时氧同位素古温度计基本原理的基础上,详细评估了成岩蚀变、生命效应、区域性海水同位素组成等不确定性因素对准确重建深时古温度的制约和解决方法;同时,还对应用氧同位素指标开展深时地表和深部水循环研究中的进展与存在的问题进行了探讨.Suitable temperature is the most important environmental parameter for the habitability of the Earth.The oxygen isotope composition of carbonate and phosphate fossils is the most widely used technique for reconstructing deep-time seawater temperatures.However,this technique is subject to uncertainties including diagenetic alteration,the vital isotope fractionation effects,regional variations in seawater oxygen isotope composition,and whether the latter changes with time in the geological past.In this contribution,we evaluated these constraints and solutions for these uncertainties.Our evaluation shows the rigorously screened oxygen isotope data provide the most continuous and reliable paleotemperature record of the Phanerozoic,generally consistent with climate changes indicated by other proxies.Lower temperatures are reconstructed from glaciated intervals(Late Ordovician,Carboniferous-Early Permian,Cenozoic)andhigher temperaturescorrespond to greenhouse intervals(Early Triassic and Middle Cretaceous).However,accurate calculation of absolute temperature is still a challenge due to the intensive dispute over constant or changingδ18O of the hydrosphere.We review and discuss the progress and remaining problems in using oxygen isotopes in deep time to understand surface and deep-water cycling.Because of the nonlinear dependence of water vapor pressure on temperature,it is generally assumed that an increase in temperature enhances the surface water cycle and precipitation.However,the exact mechanism and magnitude of the hydrological cycle response to temperature changes,as well as its spatiotemporal characteristics,are still unclear for deep time.A systematical evaluation of this relationship since the Neogene revealed that the hydrological cycle intensifies during warm climatic conditions,but the response of the hydrologic cycle to climate is not globally uniform and exhibits a marked spatial difference.This pattern is observed as well for older times,e.g.,during the Carnian Humid Episode(Late Triassic),the increase

关 键 词：碳酸盐化石 磷酸盐化石 岩石圈 水圈 深部水循环 表层水循环 

分 类 号：P53[天文地球—古生物学与地层学] P736.22[天文地球—地质学]