Sedimentology and luminescence ages of Glacial Lake Humber deposits in the central Vale of York

The sedimentary sequence through the Hemingbrough Formation exposed at two sites in the central part of the Vale of York, south of the Escrick moraine ridge, is described and used to reconstruct the palaeoenvironmental history of Glacial Lake Humber. Interbedded wave ripples and laminated silts and clays at both sites indicate that Lake Humber was characterised by fluctuating water levels, often no deeper than wave base. Optically stimulated luminescence ages of 21.0 ± 1.9, 21.9 ± 2.0, and 24.1 ± 2.2 kyr returned from two wave-rippled sandy beds within the glaciolacustrine sequence at Hemingbrough, c. 10 km south of the Escrick moraine ridge, provide the first direct chronological determination for the low-level phase of Lake Humber. As these beds are principally attributed to glacial meltwater emanating from the Vale of York ice lobe of the British Ice Sheet, when its margin was at or near the Escrick moraine ridge, this corroborates the interpretation that this ridge marks the LGM ice limit.     

Stratigraphy, depositional environments and level reconstruction of the last interglacial Lake Samra in the Dead Sea basin

In this paper we describe the stratigraphy and sediments deposited in Lake Samra that occupied the Dead Sea basin between ∼ 135 and 75 ka. This information is combined with U/Th dating of primary aragonites in order to estimate a relative lake-level curve that serves as a regional paleohydrological monitor. The lake stood at an elevation of ∼ 340 m below mean sea level (MSL) during most of the last interglacial. This level is relatively higher than the average Holocene Dead Sea (∼ 400 ± 30 m below MSL). At ∼ 120 and ∼ 85 ka, Lake Samra rose to ∼ 320 m below MSL while it dropped to levels lower than ∼ 380 m below MSL at ∼ 135 and ∼ 75 ka, reflecting arid conditions in the drainage area. Lowstands are correlated with warm intervals in the Northern Hemisphere, while minor lake rises are probably related to cold episodes during MIS 5b and MIS 5d. Similar climate relationships are documented for the last glacial highstand Lake Lisan and the lowstand Holocene Dead Sea. Yet, the dominance of detrital calcites and precipitation of travertines in the Dead Sea basin during the last interglacial interval suggest intense pluvial conditions and possible contribution of southern sources of wetness to the region.     

A late Holocene paleoclimatic history of Lake Tanganyika, East Africa

A nearshore core (LT03-05) from the north basin of Lake Tanganyika provides diatom, pollen, and sedimentary time series covering the last ca. 3800 yr at 15-36 yr resolution. A chronology supported by 21 AMS dates on terrestrial and lacustrine materials allows us to account for ancient carbon effects on ¹⁴C ages and to propose refinements of the region's climatic history. Conditions drier than those of today were followed after ca. 3.30 ka by an overall wetting trend. Several century-scale climate variations were superimposed upon that trend, with exceptionally rainy conditions occurring 1.70-1.40 ka, 1.15-0.90 ka, 0.70-0.55 ka, and 0.35-0.20 ka. Around 0.55-0.35 ka, during the Spörer sunspot minimum, drier conditions developed in the northern Tanganyika basin while more humid conditions were registered at Lakes Victoria and Naivasha. This indicates significant variability in the nature and distribution of near-equatorial rainfall anomalies during much of the Little Ice Age.     

西藏班公湖岛弧带含硫化镍超基性岩的源区性质与基底背景

青藏高原班公湖一怒江成矿带上的超基性岩型硫化镍矿化是近年来在西藏地区发现的矿化新类型.文章根据成矿带西段班公湖地区含镍超基性岩体的岩石地球化学和Sr、Pb同位素分析结果,论述了含镍超基性岩浆的源区性质及生成条件,并根据锆石U-Pb LA-ICP-MS年龄测定结果,探讨了藏西北地区的基底背景.研究发现,班公湖地区的含镍超基性岩体以富集大离子不相容元素Rb、Th、U、Sr、Pb,亏损Ba、K为特点,高场强元素亏损Nb、Ti,富集Ta;稀士元素相对球粒陨石亏损强烈,但轻稀土元素相对富集.这些特点一致反映出含矿岩浆产生于受俯冲沉积物熔体交代的富集型岩石圈地幔源区.岩浆的生成深度较浅,为尖晶石二辉橄榄岩相,源区部分熔融程度较低,大体在10%左右.岩石中集中出现一批24.79亿年的残留锆石年龄,标志着当时班公湖中特斯洋盆沉积物的物源区较为单一,主要来自太古代末-元古代初的古老基底,并且推测太古代与元古代之交(25亿年)有可能是藏西北的一个古陆壳快速生长期.     

History of the Limnological Institutes at Lake Constance

This contribution tells the history of the limnological institutes, which were founded at the shores of Lake Constance. The history starts in the late 19th century examining the scientific and personal background of two institutes, the “Anstalt für Bodenseeforschung” in Konstanz-Staad (no longer existing) and the “Institut für Seenforschung und Seenbewirtschaftung” in Langenargen, both founded in 1919/1920. It follows the turbulent history of the institutes during the early 20th century, the 3rd Reich, and the Federal Republic of Germany and examines their competition until their unification in 1970. A third institute, the precursor of the current Limnological Institute of the University of Konstanz was founded in 1948 in the small Black Forest village Falkau, and moved to Konstanz in 1970. In addition, the role of leading limnologists of their time, e.g. Max Auerbach, Reinhard Demoll, Hans-Joachim Elster and August Thienemann in founding and shaping these institutes is described.     

Role of reservoir regulation and groundwater feedback in a simulated ground-soil-vegetation continuum: A long-term regional scale analysis

The regional terrestrial water cycle is strongly altered by human activities. Among them, reservoir regulation is a way to spatially and temporally allocate water resources in a basin for multi-purposes. However, it is still not sufficiently understood how reservoir regulation modifies the regional terrestrial- and subsequently, the atmospheric water cycle. To address this question, the representation of reservoir regulation into the terrestrial component of fully coupled regional Earth system models is required. In this study, an existing process-based reservoir network module is implemented into NOAH-HMS, that is, the terrestrial component of an atmospheric–hydrologic modelling system, namely, the WRF-HMS. It allows to quantitatively differentiate role of reservoir regulation and of groundwater feedback in a simulated ground-soil-vegetation continuum. Our study focuses on the Poyang Lake basin, where the largest freshwater lake of China and reservoirs of different sizes are located. As compared to streamflow observations, the newly extended NOAH-HMS slightly improves the streamflow and streamflow duration curves simulation for the Poyang Lake basin for the period 1979–1986. The inclusion of reservoir regulation leads to major changes in the simulated groundwater recharges and evaporation from reservoirs at local scale, but has minor effects on the simulated soil moisture and surface runoff at basin scale. The performed groundwater feedback sensitivity analysis shows that the strength of the groundwater feedback is not altered by the consideration of reservoir regulation. Furthermore, both reservoir regulation and groundwater feedback modify the partitioning of the simulated evapotranspiration, thus affecting the atmospheric water cycle in the Poyang Lake region. This finding motivates future research with our extended fully coupled atmospheric–hydrologic modelling system by the community.     

国家风景名胜区景观遗产的三维培育研究--以青海湖为例

国家风景名胜区以其自然与人文美成为旅游与研究的热点。将国家风景名胜区的景观遗产划分为自然景观遗产、物质性历史文化遗产、非物质及口头文化遗产三维,并且探讨了景观遗产的培育理念。以青海湖国家风景名胜区为例,实证研究了其自然景观遗产的培育、物质性历史文化遗产的培育、非物质及口头文化遗产的培育。最后讨论了三个问题：对资源的重新认识、实证对其他案例的借鉴、三维培育模式的提取。     

气候变暖背景下极端气候对青海祁连山水文水资源的影响

利用青海祁连山区极端气候要素和青海湖、哈拉湖及主要河流的水文资料,研究表明：冷夜日数（10%）呈显著减少趋势,暖夜日数（90%）呈显著增加趋势;年大风日数显著减少;年降水量21世纪初增加趋势最为显著并发生突变,降水量增加幅度中西段大于东段;≥ 5 mm、≥ 10 mm、≥ 25 mm年降水日数呈显著增加趋势,进入21世纪后更为明显,而≥ 0.1 mm年降水日数呈减少趋势;年平均大风日数与湖泊水位、河流流量变化呈负相关,大风天气的减少,可以缓解湖面和土壤因蒸发而导致的水分损失,对植被的改善可增加径流的产生,流入湖泊的流量增加;降水量与湖泊水位、河流流量呈正相关,受21世纪降水量增加的影响青海湖水位逐年上升,共上升1.67 m,达到20世纪70年代末的水位,中西部主要河流流量近几年也达到最大值,而东段流量增加不明显;祁连山区≥ 5 mm、≥ 10 mm、≥ 25 mm年平均降水量与湖泊、河流流量变化呈正相关,各量级年降水量对湖泊水位、河流流量的增加贡献显著。     

The lacustrine microbial carbonate factory of the successive Lake Bonneville and Great Salt Lake,Utah, USA

The Bonneville Basin is a continental lacustrine system accommodating extensive microbial carbonate deposits corresponding to two distinct phases: the deep Lake Bonneville (30 000 to 11 500 ¹⁴C bp ) and the shallow Great Salt Lake (since 11 500 ¹⁴C bp ). A characterization of these microbial deposits and their associated sediments provides insights into their spatio‐temporal distribution patterns. The Bonneville phase preferentially displays vertical distribution of the microbial deposits resulting from high‐amplitude lake level variations. Due to the basin physiography, the microbial deposits were restricted to a narrow shoreline belt following Bonneville lake level variations. Carbonate production was more efficient during intervals of relative lake level stability as recorded by the formation of successive terraces. In contrast, the Great Salt Lake microbial deposits showed a great lateral distribution, linked to the modern flat bottom configuration. A low vertical distribution of the microbial deposits was the result of the shallow water depth combined with a low amplitude of lake level fluctuations. These younger microbial deposits display a higher diversity of fabrics and sizes. They are distributed along an extensive ‘shore to lake’ transect on a flat platform in relation to local and progressive accommodation space changes. Microbial deposits are temporally discontinuous throughout the lake history showing longer hiatuses during the Bonneville phase. The main parameters controlling the rate of carbonate production are related to the interaction between physical (kinetics of the mineral precipitation, lake water temperature and runoff), chemical (Ca²⁺, Mg²⁺ and HCO₃^? concentrations, Mg/Ca ratio, dilution and depletion) and/or biological (trophic) factors. The contrast in evolution of Lake Bonneville and Great Salt Lake microbial deposits during their lacustrine history leads to discussions on major chemical and climatic changes during this interval as well as the role of physiography. Furthermore, it provides novel insights into the composition, structure and formation of microbialite‐rich carbonate deposits under freshwater and hypersaline conditions.