Holocene environmental and climatic changes inferred from Wulungu Lake in northern Xinjiang, China

Sedimentological, geochemical and palynological data from Wulungu Lake in northern Xinjiang, China, are used to reconstruct environmental and climate changes since 9550 cal yr BP. High abundance of Sparganium and Poaceae, low Md (median diameter) and δ¹³C_organic values indicate aridity between 9550 and 6730 cal yr BP. High Md and δ¹³C_organic values, and the prevalence of desert-steppe and steppe vegetation between 4200 and 560 cal yr BP, indicate that effective moisture increased after 6730 cal yr BP, peaking at 4200 and 560 cal yr BP. Low Md values, a negative excursion of δ¹³C_org, and the transition from steppe to desert vegetation since 560 cal yr BP reflect a decrease in effective moisture during the latest Holocene. Late Holocene human activities were indicated by sharp increase in the abundance of Pediastrum then. Variations in carbonate contents indicate that temperature was generally high between 9550 and 7740 cal yr BP, low between 7740 and 6730 cal yr BP, intermediate between 6730 and 560 cal yr BP, and low during the last 560 yr. Regional comparison indicates that the Asian monsoon did not extend to Wulungu Lake and westerlies were the main factor in determining the moisture availability during the Holocene.     

陆表海盆地含煤地层的高分辨率层序地层研究

分析了鲁西南煤田陆表海盆地沉积充填序列中的T-R旋回特征;划分出陆表海盆地高分辨层序,依次为构造层序、超层序、层序、小层序组、小层序及更小级别的层序单元。在研究了陆表海盆地海平面变化特点及其对煤聚积控制作用的基础上,提出了“海侵事件成煤”观点,认为海侵事件是控制陆表海盆地煤聚积的重要事件,突发性海侵事件界面、暴露土壤化事件界面和海侵事件成因的煤层均具有等时性对比意义。      

北京斋堂东胡林全新世早期遗址的黄土剖面

门头沟斋堂东胡林遗址是目前北京地区发现的最早且内涵最丰富的新石器早期遗址(9281±120～8270±60 a BP)。该遗址的黄土剖面清晰,包含了晚更新世及早全新世的黄土堆积、全新世早期的沉积间断及埋藏古土壤。在相对精确的~(14)C年龄时间框架下,本文对保存该遗址的黄土剖面的分层、黄土的粒度特征、矿物成分、化学成分、孢粉图谱及蜗牛的相对丰度进行了研究。分析表明本地区晚更新世气候比较干冷,气候的明显转暖应在全新世早期(早于9281±120 a BP),在约8500 a BP华北地区的年均温度可能已达到比现在高约2～3℃左右的状况。正是在这样的环境背景下,山顶洞人的后裔们,在清水河畔的阶地上开始了全新的生活。     

西辽河平原东部沼泽发育与中全新世早期以来古环境演变

根据典型沼泽剖面14 C测年及其树木年轮校正、孢粉分析、粘土矿物X 衍射分析、泥炭植物残体鉴定和沉积物的化学元素聚集与迁移资料 ,研究了中全新世以来西辽河平原东部沼泽发育过程与古环境演变及其二者的关系。结果表明 ,位于生态环境过渡带、脆弱带的沼泽发生、发育对环境变化尤为敏感。中全新世早期以来 ,环境变化频繁 ,由此导致沼泽发育出现多次形成、发育、退化、消亡、再生循环变化。沼泽发育与古环境演变可划分为 6个时期 :中全新世早期沼泽孕育与萌芽发育期 ;中全新世中期沼泽旺盛发育期 ;中全新世中晚期沼泽间断发育期 ;中全新世晚期沼泽退化发育期 ;晚全新世早期沼泽复苏期 ;晚全新世晚期沼泽消亡期。距今 5 80 0年左右为本区全新世沼泽最早发育期。沼泽发育也遵循富营养沼泽长期发展的模式     

云南华坪全新世大暖期百年尺度的季风气候的石笋记录

通过对云南华坪葫芦洞FL4石笋进行高精度的ICP—MS—230Th/U测年和高分辨率的碳、氧同位素分析,建立了该地区6 060-4 185 a BP间高分辨率的西南季风气候变化时间序列,进而揭示了该时段发生的3次季风减弱事件。 这3次百年尺度（持续时间为90～240a）的干旱寒冷事件,分别发生在6 060－5 950 a BP、5 380－5 140 a BP、4 810-4 620 a BP,呈台阶状演变;而石笋的碳同位素记录揭示了2次强降水事件,分别发生在5 503－5 443 a BP和4 210-4 185 a BP,持续时间分别为25a和60a。石笋碳、氧同位素记录的西南季风减弱以及强降水事件明显受太阳辐射强度的控制。分辨率为3~10 a的碳、氧同位素记录表明,在百年尺度的西南季风气候变化上,叠加了一系列十年尺度的气候突变事件,呈锯齿状的高频波动。这些短时间尺度的季风气候波动事件与树轮14C 残差、冰芯记录极为相似,反映低纬度地区石笋记录的季风气候与高纬度及北极地区的气候具有极好的可比性,可能主要是受中低纬度太阳辐射强度以及北半球大气环流的影响,太阳辐射强度的变化是控制印度季风的快速推进或退出(萎缩)以及百年尺度上的气候波动的主要动因。      

Glacier Relics of the Last Glacial and Holocene Periods Discovered in the Middle‐low Mountains of Eastern China: Sedimentary Sequences and Environmental Evolution of Mengshan Mountain in Shandong Province since 80 ka

The goal of this research study is to describe academic issues which have been debated in the field of Chinese geosciences for a century. In 1922, Jonquei S. Lee(Li Siguang) discovered Quaternary glacial relics at Taihang Mountainin eastern China. In 1947, he published his research findings in the magazine Mount Lushan in Glacial Age. The research results had established three Ice Ages: Poyang(Gonzi), Dagu(Minde), and Lushan(Lisi). However, at that time, no Wurm glacial relics of the last Ice Age had been found in Lushan Mountain. Since then, the research team represented by Shi Yafeng, who is considered to be "the father of glaciers in China", questioned Jonquei S. Lee's research results and concluded that "Professor Jonquei S. Lee's Quaternary glacier research in Lushan Mountain having misread the debris flow". In 2005, the "middle-low mountains" in eastern China were finally defined as follows: "We clearly and unambiguously believe that there were no glacial activities in the middle-low mountainous areas of eastern China(east of 102° to 104°E; below 3,000 and 2,500 m) during the Quaternary Period". Currently, the long-standing academic debate appears to have come to a conclusion. As of 2015, the author and others began to investigate and study the Quaternary glacial relics in Mengshan Mountain(1,156 m above sea level), Shandong Province, one of the "middle-low mountains" of eastern China. The relics have been observed to posses the systematic features of glacial erosion, trough and valley striations, and moraine deposits. The applied dating method shave confirmed that there were not only glacial relics of the last Ice Age(Wurm), but also Holocene glacial relics in the Mengshan Mountain area. Therefore, in order to further establish the corresponding relationship between the glacier, loess, stream sediment series, and MIS in the Mengshan Mountain area, a large number of chronological studies have been carried out regarding the various types of sediments in the area, and 24 dating datahave been obtained using OSL, CRN, and 14 Cmethods.On this basis, the corresponding relationship between the sedimentary sequences and the MIS was established for the first time in eastern China, which in dicates the environmental changes which had occurred in eastern China since 80 ka. These discoveries s and chronological study results confirm the existence of the Last Ice Age, as well as Holocene glacial relics at Mengshan Mountain, there by confirming that Quaternary glaciation had occurred in the middle-low mountain areas of eastern China.     

太白山佛爷池剖面的全新世环境变化信息

太白山佛爷池海拔3410m,是一个发育在古冰斗中的冰蚀湖。自湖中210cm沉积剖面进行沉积物粒度、孢粉和测年采样分析,表明自8200aBP以来的环境经历了明显的冷暖干湿变化。8200~6800aBP温暖湿润,在7200aBP出现明显增温;6800~5900aBP气候开始波动,大约在6300aBP有一次短暂的变冷,在6000aBP前后出现明显暖期;5900~4800aBP气温下降,大约在5200aBP达到最低,然后气温缓慢回升;4800~2600aBP气候较为温暖湿润,大约在3000aBP达到最高;2600~900aBP气候变冷湿,大约1500aBP达到最低;900aBP~现代变好。      

含煤岩系沉积学研究的几点思考

根据沉积学和煤地质学的理论和方法 ,对聚煤作用、聚煤中心、煤层在地层格架中的分布、煤的前身--泥炭和成煤基地--沼泽地 ,以及煤和煤系中的矿物组分--高岭石进行了介绍、分析、论述 ,并再次提出华北晚古生代海侵问题。     

重庆丰都玉溪剖面的沉积学和气候意义

重庆丰都玉溪剖面AMS14C测年（校正为日历年）配合考古器物断代,证实约8 500～4 800 aBP间该剖面地层基本连续。玉溪剖面下部洪水淤砂—坡积物互层（31～10层）与上部坡积层（9～3层）形成鲜明对比,反映沉积物源和沉积环境曾发生过显著变化。研究认为,Rb、Sr等代用指标曲线的变化特征与剖面沉积结构变化相吻合,揭示了剖面上、下沉积结构的差异主要与不同气候背景有关;剖面下部堆积较厚、持续时间较短及沉积速率较快的洪水淤砂—坡积物互层,是研究区气候不稳定条件下水文异常变化的结果。进一步分析认为,该剖面沉积物的微观隐性代用指标与宏观显性结构的对应性特点还反映,研究区全新世大暖期气候存在阶段性的变化,约8 500～7 200 aBP为大暖期中的气候不稳定阶段;而约7 200～4 800 aBP则体现了大暖期鼎盛阶段暖湿稳定的气候特点,其转折点发生在7 200 aBP前后。     

洪积扇上全新世古土壤的特点及环境意义--以临汾盆地东坡沟剖面为例

通过对山西襄汾东坡沟全新世黄土剖面地层学和土壤学的研究,以及碳酸钙、铁和粒度的测定,发现全新世古土壤中碳酸钙经历了明显的淋溶与淀积,古土壤上部CaCO₃平均含量10.58%,下部为18.47%,CaCO₃结核的淀积深度约为1.1m,铁在古土壤顶部有微弱的淋移和富集,粘化作用不明显。成壤作用始于全新世大暖期之初,较为强烈的成壤作用发生于大暖期的晚期(4100aB.P～3100aB.P),这一阶段土壤湿度大,气候波动小,CaCO₃淋溶较强。大暖期结束后,冬季风在黄土高原占主导地位,土壤的淋溶作用和粘土作用均有一定程度减弱,显示气候干旱的趋势。该剖面位于古山前洪积扇前端,地形较高,降水易分散,淋溶作用总的说来不强烈,土壤上部CaCO₃残留较多,CaCO₃淀积深度较浅,土壤类型接近黑垆土。