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

作　　者：Meng LI Xin LI Stephen P.HESSELBO Mingjie LI Wenjin LIU Wei WU Jienan PAN Ruizhen GAO 

机构地区：[1]School of Resources and Environment,Henan Polytechnic University,Jiaozuo 454000,China [2]Camborne School of Mines and Environment and Sustainability Institute,University of Exeter,Penryn TR109FE,United Kingdom [3]Qinghai No.105 Coal Geological Exploration Team,Xining 810000,China

出　　处：《Science China Earth Sciences》2024年第1期252-267,共16页中国科学（地球科学英文版）

基　　金：This work was supported by the National Natural Science Foundation of China(Grant Nos.41502108,42372206&41602123);the China Postdoctoral Science Foundation(Grant No.2016T90667);the China Scholarship Council Project(Grant No.201907770004);the Fundamental Research Funds for the Universities of Henan Province(Grant No.NSFRF220401).

摘　　要：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(~183 Ma)and the late Pliensbachian cooling event(~185 Ma).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(174.2 Ma to 190.9 Ma)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 sealevel 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 longeccentricity cycles mainly regulate variations of lake level and sea level by controlli

关 键 词：Milankovitch cycles Orbital forcing Sedimentary noise model Lake level Continental basins 

分 类 号：P534.52[天文地球—古生物学与地层学] P512.2[天文地球—地质学]