晚更新世以来冲绳海槽天文驱动的气候变化:来自CSHC-15钻孔的证据  

Astronomically forced climate changes in the Okinawa Trough since the Late Pleistocene:Evidence from CSHC-15 core

作　　者：王蒙 李清 窦衍光 蔡峰 李明松 WANG Meng;LI Qing;DOU Yanguang;CAI Feng;LI Mingsong(Key Laboratory of Orogenic Belts and Crustal Evolution,MOE,School of Earth and Space Sciences,Peking University,Beijing 100871;Qingdao Institute of Marine Geology,China Geological Survey,Qingdao 266071,Shandong;Laboratory for Marine Mineral Resources,Laoshan Laboratory,Qingdao 266237,Shandong;Laboratory for Marine Geology,Laoshan Laboratory,Qingdao 266237,Shandong)

机构地区：[1]北京大学地球与空间科学学院,造山带与地壳演化教育部重点实验室,北京100871 [2]中国地质调查局,青岛海洋地质研究所,山东青岛266237 [3]崂山实验室,海洋矿产资源评价与探测技术功能实验室,山东青岛266237 [4]崂山实验室,海洋地质过程与环境功能实验室,山东青岛266237

出　　处：《第四纪研究》2023年第6期1711-1721,共11页Quaternary Sciences

基　　金：国家重点研发计划项目(批准号:2022YFF0802900和2018YFC0310001);国家自然科学基金项目(批准号:42072040);北京大学博雅博士后计划项目(批准号:2106390477);中国地质调查项目(批准号DD20230401)共同资助。

摘　　要：东海冲绳海槽是一个年轻的弧后盆地,自中新世以来接受了来自长江、黄河以及陆架输送的物质,具有高沉积速率和富有机质等沉积特征,但是沉积记录的年代学约束较为薄弱,影响了对气候信号变化的解读。本研究以冲绳海槽中北部CSHC-15钻孔的60 m连续样品为对象,选取高分辨率的主微量元素含量作为古气候替代指标开展天文年代学分析,采用碳同位素测年数据和底栖有孔虫氧同位素记录作为年龄约束,建立该钻孔约200 ka以来的沉积记录变化。通过对沉积物时间域Al、K、Ti等主微量元素含量序列进行频谱分析,观察到显著的100 ka短偏心率、41 ka斜率、约23 ka岁差以及10 ka半岁差周期。由于该钻孔的底栖有孔虫种属存在差异,在没有放射性同位素年龄的约束下,氧同位素值与国际标准曲线LR04的对比结果效果不佳。因此,本研究利用La04天文轨道模型的岁差周期进行约束,进行精细的天文调谐,以获得可靠的地层年代框架;此外,结合贝叶斯统计的年龄模型分析方法,计算了该天文年代标尺的误差范围,从而进一步提高了对冲绳海槽晚更新世以来沉积记录年代的可靠性,其结果有助于深入探究气候变化和环境演化的影响。Okinawa Trough is a young back-arc basin that has received sediments from the Yangtze River,Yellow River,and East China Sea shelf since the Middle Miocene,exhibiting characteristics such as high sedimentation rates and organic-rich sediments.However,the chronostratigraphic constraints in the sedimentary record are relatively weak,which has made it challenging to preserve and interpret climate change signals.In this study,we use high-resolution concentrations of elements from the continuous samples of the core CSHC-15 with thick-60 m in the northern Okinawa Trough.Based on age constraints of carbon isotope dating and benthic foraminiferal oxygen isotope records,we establish a sedimentary record covering approximately 200 ka for this core.Spectral analysis of the time series of element concentrations,such as aluminum and iron,reveals significant periodicities at 100 ka(short eccentricity),41 ka(obliquity),ca.23 ka(precession),and 11 ka(half-precession),respectively.Due to the variations in benthic foraminiferal species and the lack of constraints from radioisotope ages,the comparison between oxygen isotope values and the LR04 stack yields unreliable results.To construct a robust chronostratigraphic framework,we apply the precession cycle of the La04 astronomical solution for tuning and incorporate a Bayesian statistical age modeling approach to calculate the uncertainty range of this astronomical timescale.These efforts contributed to a more reliable chronostratigraphic framework for the Late Pleistocene to Holocene sedimentary record in the Okinawa Trough and advance our understanding of the influences of climate change and environmental evolution.

关 键 词：天文年代标尺 贝叶斯统计 天文周期 晚更新世 冲绳海槽 

分 类 号：P534.631[天文地球—第四纪地质学] P593[天文地球—古生物学与地层学] P512.6[天文地球—地质学]