Head Martin J
Department of Earth Sciences, Brock University, St. Catharines, Ontario L2S 3A1 Canada.
Prog Earth Planet Sci. 2021;8(1):50. doi: 10.1186/s40645-021-00439-2. Epub 2021 Sep 3.
The Global Boundary Stratotype Section and Point (GSSP) defining the base of the Chibanian Stage and Middle Pleistocene Subseries at the Chiba section, Japan, was ratified on January 17, 2020. Although this completed a process initiated by the International Union for Quaternary Research in 1973, the term Middle Pleistocene had been in use since the 1860s. The Chiba GSSP occurs immediately below the top of Marine Isotope Substage (MIS) 19c and has an astronomical age of 774.1 ka. The Matuyama-Brunhes paleomagnetic reversal has a directional midpoint just 1.1 m above the GSSP and serves as the primary guide to the boundary. This reversal lies within the Early-Middle Pleistocene transition and has long been favoured to mark the base of the Middle Pleistocene. MIS 19 occurs within an interval of low-amplitude orbital eccentricity and was triggered by an obliquity cycle. It spans two insolation peaks resulting from precession minima and has a duration of ~ 28 to 33 kyr. MIS 19c begins ~ 791-787.5 ka, includes full interglacial conditions which lasted for ~ 8-12.5 kyr, and ends with glacial inception at ~ 774-777 ka. This inception has left an array of climatostratigraphic signals close to the Early-Middle Pleistocene boundary. MIS 19b-a contains a series of three or four interstadials often with rectangular-shaped waveforms and marked by abrupt (< 200 year) transitions. Intervening stadials including the inception of glaciation are linked to the calving of ice sheets into the northern North Atlantic and consequent disruption of the Atlantic meridional overturning circulation (AMOC), which by means of the thermal bipolar seesaw caused phase-lagged warming events in the Antarctic. The coherence of stadial-interstadial oscillations during MIS 19b-a across the Asian-Pacific and North Atlantic-Mediterranean realms suggests AMOC-originated shifts in the Intertropical Convergence Zone and pacing by equatorial insolation forcing. Low-latitude monsoon dynamics appear to have amplified responses regionally although high-latitude teleconnections may also have played a role.
定义日本千叶剖面里番年阶底部和中更新世亚统的全球界线层型剖面和点位（GSSP）于2020年1月17日获得批准。尽管这完成了国际第四纪研究联合会于1973年启动的一个进程，但“中更新世”这一术语自19世纪60年代以来就一直在使用。千叶GSSP位于海洋同位素亚阶段（MIS）19c顶部之下紧邻处，天文年龄为774.1 ka。松山-布容古地磁反转的方向中点在GSSP上方仅1.1米处，是该界线的主要标志。这次反转处于早-中更新世过渡阶段，长期以来一直被认为是中更新世底部的标志。MIS 19发生在低振幅轨道偏心率区间内，由倾角周期触发。它跨越了由岁差最小值导致的两个日照峰值，持续时间约为28至33 kyr。MIS 19c始于约791 - 787.5 ka，包括持续约8 - 12.5 kyr的完整间冰期条件，并以约774 - 777 ka的冰川开始为结束。这次开始在早-中更新世边界附近留下了一系列气候地层信号。MIS 19b - a包含一系列三到四个间冰阶，通常具有矩形波形，以突然（<200年）转变为特征。包括冰川开始在内的中间冰阶与冰盖崩解进入北大西洋北部以及随后大西洋经向翻转环流（AMOC）的中断有关，这通过热双极跷跷板效应在南极引发了相位滞后的变暖事件。MIS 19b - a期间亚洲-太平洋和北大西洋-地中海区域间冰阶-冰阶振荡的一致性表明，AMOC导致了热带辐合带的移动，并由赤道日照强迫进行节奏控制。尽管高纬度遥相关可能也起到了作用，但低纬度季风动力学似乎在区域上放大了响应。
