2023年12月15日出版的《中国科学：地球科学》杂志发表了河南理工大学李猛研究团队的最新成果，他们的研究利用沉积噪声模拟重建了早侏罗世冰室-(超)温室湖泊水位变化的轨道步调和长期演化。

研究通过沉积噪声模拟，给出了从早更新世到早古生代这一关键时期的超长非海相湖泊水位记录，基于对柴达木盆地岩石颜色资料(CIE b*)的旋回地层学分析，构建了16.7 Myr长的天文时间尺度(174.2 Ma-190.9 Ma），研究结果记录了5-10个百万年(Myr)尺度上的湖泊水位振荡，结果显示了与长期气候变化和极端气候事件有明显的相关性，以及1-2.5 Myr尺度的湖泊水位变化，这种变化主要由2.4 Myr尺度的长偏心率作用力和1.2 Myr的倾角作用力引起的。在Pliensbachian阶段，1.2 Myr尺度的湖泊水位变化与同期海平面变化是同步的。极地地区短暂或永久冰盖的轨道作用力生长和衰减，被解释为控制大陆湖泊水位和全球海平面的同步起伏。

然而，在Toarcian无冰温室效应-(超)温室效应期间，1.2 Myr尺度的湖泊水位变化与全球海平面呈反相关系，表明大陆水库(湖泊和地下水)与全球海洋之间存在“跷跷板”相互作用。2.4 Myr长偏心率旋回主要通过控制小尺度大陆冰盖的生长和衰减来调节湖泊和海平面的变化，这在Pliensbachian阶段尤为明显。这些发现表明，在Pliensbachian-Toarcian冰期-(超)温室期间，水文循环模式发生了显著转变，这为研究全球海平面变化(如冰川—海平面上升和含水层—海平面上升)，和非海相地层学中长周期天文作用力提供了新的视角和证据。

据悉，湖泊水位变化对大陆盆地的古环境演化、资源赋存、陆地碳收支、生物多样性等具有重要影响。气候是控制湖泊水位变化的最关键因素之一。早侏罗世的古气候表现为冰室到(超)温室的振荡，并伴有间断的间歇性极端气候事件(高温和变冷)，如Toarcian海洋缺氧事件(约183Ma)和晚Pliensbachian变冷事件(约185Ma)。由于缺乏持续高分辨率的非海相证据，人们对早侏罗世冰室-(超)温室期间湖泊平面演变和地表水文循环知之甚少。

附：英文原文

Title: Orbital pacing and secular evolution of lake-level changes reconstructed by sedimentary noise modeling during the Early Jurassic icehouses-(super)greenhouses

Author: Meng LI, Xin LI, Stephen P. HESSELBO, Mingjie LI, Wenjin LIU, Wei Wu, Jienan PAN, Rui zhen GAO

Issue&Volume: 2023-12-15

Abstract: Lake-level changes can significantly affect paleoenvironmental evolution, resource occurrence, terrestrial carbon budget, and biodiversity in continental basins. Climate is one of the most critical factors controlling lake-level changes. Paleoclimate of the Early Jurassic has been evidenced by oscillating icehouses to (super) greenhouses with interrupted intermittent extreme climatic events (hyperthermal and cooling), e.g., the Toarcian oceanic anoxic event (~183Ma) and the late Pliensbachian cooling event (~185Ma). Lake-level evolution and hydrologic cycling on Earth’s surface during the Early Jurassic icehouses-to-(super)greenhouses are thus far poorly understood due to a lack of continuous high-resolution nonmarine evidence. Here we present a super-long nonmarine lake level record for this pivotal interval from the early Pliensbachian to Toarcian by sedimentary noise modeling, and construct a 16.7-Myr-long astronomical time scale (174.2Ma to 190.9Ma) based on cyclostratigraphy analysis of rock color datasets (CIE b*) of the Qaidam Basin. Our results document lake-level oscillations on a 5- to 10-million-year (Myr) scale which shows a pronounced correlation with long-term climate variation and extreme climatic events, and 1- to 2.5-Myr-scale lake-level changes that are prominently paced by the 2.4-Myr long-eccentricity forcing and the 1.2-Myr obliquity forcing. At the Pliensbachian Stage, the 1.2-Myr-scale lake-level changes are in phase with the coeval sea-level variations. Orbitally forced growth and decay of the ephemeral or permanent ice sheets in polar regions are interpreted to control the synchronous ups-and-downs of continental lake level and global sea level. However, during the Toarcian ice-free greenhouses to (super)greenhouses, the 1.2-Myr-scale lake-level variations show an anti-phase relationship with global sea level, indicating a ‘seesaw’ interaction between continental reservoirs (lakes and groundwater) and global oceans. The 2.4-Myr long-eccentricity cycles mainly regulate variations of lake level and sea level by controlling the growth and decay of small-scale continental ice sheets, which is especially notable during the Pliensbachian Stage. These findings indicate a remarkable transition of hydrological cycling pattern during the Pliensbachian-Toarcian icehouses to (super)greenhouses, which provides new perspectives and evidence for investigating the hypothesis of global sea-level changes (e.g., glacio-eustasy and aquifer-eustasy) and long-period astronomical forcing in nonmarine stratigraphy.

DOI: 10.1007/s11430-023-1187-8

Source: https://www.sciengine.com/10.1007/s11430-023-1187-8