晚中新世以来东赤道太平洋冷舌的地质演化  

Evolution of the East Equatorial Pacific cold tongue since the late Miocene

作　　者：田军[1] 刘晶晶[1] 柳中晖[2] Tian Jun;Liu Jingjing;Liu Zhonghui(State Key Laboratory of Marine Geology,Tongji University,Shanghai 200092;Department of Earth Sciences,The University of Hong Kong,Hong Kong 999077)

机构地区：[1]同济大学海洋地质国家重点实验室,上海200092 [2]香港大学地球科学系,香港999077

出　　处：《中国科学基金》2019年第6期585-591,共7页Bulletin of National Natural Science Foundation of China

基　　金：国家自然科学基金（项目批准号：41525020,41776051）的资助

摘　　要：东赤道太平洋冷舌(东太冷舌)的演变对揭示古气候变化的动力学机制存在重要的科学意义,但学术界对东赤道太平洋冷舌的形成时间和发育机制仍存在争论。我们选择东赤道太平洋暖池边缘区国际大洋发现计划(International Ocean Discovery Program,IODP)IODP-U1337站的深海沉积物,利用U3K7′温度指标,重建了过去8 Ma以来该站海水表层温度(Sea Surface Temperature,SST)记录。我们利用东太暖池区IODP-U1337站和东太冷舌区ODP846站的SST梯度(ΔSSTU1337-846),来指示东太冷舌8 Ma以来的演变历史。我们发现晚中新世以来东赤道太平洋冷舌的演变主要分为两个阶段:6.2~4.3 Ma期间,冷舌发育较为微弱,其中包括了晚中新世冷事件期间;4.3Ma至今,冷舌发育逐渐增强阶段,直到0.8 Ma左右达到现代水平。巴拿马海峡的关闭为冷舌发育提供前提条件,而在"温跃层传播机制"作用下,中高纬变冷才是上——更新世以来冷舌发育的持续动力。Understanding the evolution of the eastern equatorial Pacific(EEP)cold tongue is vital to reveal the dynamics of the past climate change.However,the timing and mechanisms of the eastern equatorial Pacific cold tongue development are intensely debated on geological time scales.We reconstructed the sea surface temperature(SST)changes by the alkenone method over the past 8 million years,and used the SST gradient(ΔSSTU1337-846)between Site IODP-U1337 in the Eastern Pacific Warm Pool and Site ODP846 in the cold tongue core area to investigate the cold tongue development since the late Miocene.The cold tongue evolution could be divided into two stages since the late Miocene.The cold tongue remained very weak between 6.2 and 4.3 Ma,but then underwent gradual intensification until^0.8 Ma when the cold tongue developed into its modern state.We suggest that the cold tongue development was preconditioned by the closure of Central America Seaway and was intensified by the cooling in extratropical regions through the‘thermocline tunneling’mechanism.

关 键 词：东太冷舌 晚中新世 演化 

分 类 号：P73[天文地球—海洋科学]