37ka以来日本海沉积物有机质碳和氮稳定同位素变化及其古海洋学意义  

Stable carbon and nitrogen isotope variations in sedimentary organic matter in the Sea of Japan since 37ka:Paleoceanographic implications

作　　者：邹建军 宗娴 朱爱美 豆汝席 林锦辉 冯旭光 董智 Sergey A.GORBARENKO 郑立伟 石学法 ZOU Jianjun;ZONG Xian;ZHU Aimei;DOU Ruxi;LIN Jinhui;FENG Xuguang;DONG Zhi;Sergey A.GORBARENKO;ZHENG Liwei;SHI Xuefa(Key Laboratory of Marine Geology and Metallogeny,First Institute of Oceanography,Ministry of Natural Resources,Qingdao 266061,China;Laboratory for Marine Geology,Pilot National Oceanography Laboratory for Marine Science and Technology(Qingdao),Qingdao 266237,China;V.I.Il'ichev Pacific Oceanological Institute,Far East Branch of the Russian Academy of Sciences,Vladivostok 690041,Russia;State Key Laboratory of Marine Resource Utilization in South China Sea,Hainan University,Haikou 570000,China)

机构地区：[1]自然资源部第一海洋研究所海洋地质与成矿作用重点实验室,山东青岛266061 [2]青岛海洋科学与技术试点国家实验室海洋地质过程与环境功能实验室,山东青岛266237 [3]俄罗斯科学院远东分院太平洋海洋研究所,俄罗斯符拉迪沃斯托克690041 [4]海南大学南海海洋资源利用国家重点实验室,海南海口570000

出　　处：《地学前缘》2022年第4期123-135,共13页Earth Science Frontiers

基　　金：国家自然科学基金项目(41876065,41420104005);国家自然科学基金委山东海洋科学中心项目(U1606401);泰山学者攀登计划(TSPD20181216)。

摘　　要：海洋沉积物有机质碳氮稳定同位素(δ^(13)C、δ^(15)N)广泛用于有机质来源示踪、古生产力和古海洋环境重建。日本海沉积物δ^(13)C和δ^(15)N值一个显著特征是在末次冰盛期(LGM)同步负偏,但是对这一现象产生的原因以及他们的演化过程的认识仍然存在明显不足。在本研究中,我们详细调查了37 ka以来日本海中部LV53-23-1岩心沉积物δ^(13)C和δ^(15)N演化历史。结果显示,沉积物δ^(13)C和δ^(15)N分别介于-26.3‰至-22.5‰和1.6‰至6.1‰,低值出现在LGM(26.5~17 ka)暗色层状泥发育时期,指示较强的陆源输入贡献。在Heinrich冰阶1时期(17~14.5 ka),δ^(13)C和δ^(15)N快速正偏,表明日本海海洋环境发生了明显的转换,对应于对马海峡淹没及对马暖流入侵。14.5 ka之后,沉积物δ^(15)N值恢复到5‰,与开阔大洋海水硝酸盐的δ^(15)N值近似。我们采用二端员混合模型粗略地估算了有机质来源的相对贡献。LGM时期陆源有机质贡献介于65%至80%,14.5 ka以后海源有机质贡献介于60%至80%。除了增加的陆源有机质贡献以外,LGM时期沉积物δ^(15)N亏损还涉及如下过程:(1)较高的含Fe沙尘供给提高日本海表层海洋生物固氮效率;(2)缺氧环境盛行减弱成岩作用对沉积物δ^(15)N影响。37 ka以来,日本海沉积物δ^(13)C和δ^(15)N变化与有机质来源、营养盐的供给、表层生产力和沉积物氧化还原条件相关,实际受海平面和全球气候制约。Stable carbon and nitrogen isotopes in sedimentary organic matter(δ^(13)C and δ^(15)N)have been widely used in the organic matter source tracing and reconstruction of paleoproductivity and paleoenvironment.A pronounced feature of sedimentary δ^(13)C and δ^(15)N in the Sea of Japan is their synchronous negative excursions during the Last Glacial Maximum(LGM),yet the causes and mechanisms of this phenomenon are poorly understood.In this study,we investigated the evolutionary history of sedimentary δ^(13)C and δ^(15)N since 37 ka in core LV53-23-1 retrieved from the Oki Ridge of the central Sea of Japan.According to the results,sedimentary δ^(13)C and δ^(15)N ranged from 26.3‰ to 22.5‰ and 1.6‰ to 6.1‰,respectively,with the lower values coinciding with the deposition of dark laminated mud during the LGM(26.517 ka),indicating an increased contribution of terrestrial organic matter.Both δ^(13)C and δ^(15)N showed positive excursions during Heinrich Statidal 1(1714.5 ka),indicating distinct oceanic environmental changes in the Sea of Japan,which corresponds to the Tsushima Strait flooding and the Tsushima Warm Current invasion into the Sea of Japan at that time.After 14.5 ka sedimentary δ^(15)N reached~5‰,comparable to the average δ^(15)N of nitrate in seawater.We estimated the relative contributions of organic sources using a binary mixing model.The contribution of terrigenous organic matter ranged between 65% to 80% in the LGM,while marine source contributed between 60% to 80% since 14.5 ka.Besides,sedimentary δ^(15)N depletion during the LGM can be caused by(1)improved nitrogen fixation in the surface water of the Sea of Japan due to higher dust-borne Fe supply,and(2)decreased effects of early diagenesis on sedimentary δ^(15)N due to prevailing suboxic or anoxic environment.Taken together,the variations of sedimentary δ^(13)C and δ^(15)N in the Sea of Japan since 37 ka are controlled by eustatic sea level and global climate changes,which modulate the organic source,nutrient supply,primary p

关 键 词：碳氮稳定同位素 沉积物有机质来源 海平面 末次冰期 日本海 

分 类 号：P736.4[天文地球—海洋地质]