scholarly journals Indícios de Variações Climáticas Neo-quaternárias no Médio Vale do Rio Doce

1977 ◽  
Vol 1 ◽  
pp. 110-113
Author(s):  
Maria Regina Mousinho de Meis
Keyword(s):  
Lake Level ◽  
Lake Area ◽  
The Holocene ◽  
Slope Deposits ◽  
Hydrologic Budget ◽  
Lake Waters

A tentative stratigraphy for the Upper Quaternary events in the Jacare lake area, middle rio Doce basin, was obtained through the analysis of borehole samples. The deposition of a thick sequence os slope deposits was interrupted at the beginning of the Holocene (9.840 220 years B.P.) by a transgression of the lake waters. This submersion is thought to be contemporaneous to the expansion of the rainforest over the area. More recent fluctuations of the lake level seem to denounce variations in the hydrologic budget.

scholarly journals Variations in Lake Levels during the Holocene in North America: An Indicator of Changes in Atmospheric Circulation Patterns

2007 ◽  
Vol 39 (2) ◽  
pp. 141-150 ◽  
Author(s):  
S. P. Harrison ◽  
S. E. Metcalfe
Keyword(s):  
North America ◽  
General Circulation ◽  
Lake Level ◽  
Data Bank ◽  
Relative Depth ◽  
Lake Levels ◽  
Regional Patterns ◽  
Air Mass ◽  
The Holocene ◽  
Lake Status

ABSTRACT Fluctuations in the extent of closed lakes provide a detailed record of regional and continental variations in mean annual water budget. The temporal sequence of hydrological fluctuations during the Holocene in North America has been reconstructed using information from the Oxford Lake-Level Data Bank. This data base includes 67 basins from the Americas north of the equator. Maps of lake status, an index of relative depth, are presented for the period 10,000 to 0 yr BP. The early Holocene was characterised by increasingly arid conditions, which led to widespread low lake levels in the mid-latitudes by 9,000 yr BP. By 6,000 yr BP this zone of low lakes extended from 32o to 51oN. Many of the features of the present day lake-level pattern, particularly high lake levels north of 46oN and along the eastern seaboard, were established by 3.000 yr BP. Four distinctive regional patterns of lake behaviour through time are apparent. Histograms of lake status from 20,000 to 0 yr BP are presented for each of these regions. They illustrate the temporal patterns of lake-level fluctuations on a time scale of 103 — 104 yr. Changes in lake status over North America are interpreted as indicating displacements in major features of the general circulation, specifically the zonal Westerlies and the Equatorial Trough, as reflected by changes in air mass trajectories and hence the position of air mass boundaries over the continent.

scholarly journals Optical Stimulation Luminescence Dating of Deltas Revealed the Early to Mid-Holocene Lake-level Fluctuations of Daihai, Inner Mongolia, Northern China

2021 ◽  
Vol 9 ◽  
Author(s):  
Shixin Huang ◽  
Xi Chun
Keyword(s):  
Lake Level ◽  
Climate Changes ◽  
Asian Summer Monsoon ◽  
Regional Climate ◽  
Lacustrine Sediments ◽  
Northern China ◽  
Luminescence Dating ◽  
Lake Area ◽  
Monsoon Precipitation ◽  
Lake Level Fluctuations

Lake-level reconstruction of inland enclosed lakes especially for monsoon-sensitive areas is of great significance to reveal regional climate changes. Daihai, a typical enclosed lake at the marginal of the East Asian summer monsoon (EASM) area in north China, is sensitive to climate changes due to its unique regional characteristics. There were a series of lakeshore terraces, highstand lacustrine sediments, and braided river deltas, providing sufficient geomorphologic and stratigraphic evidence for the reconstruction of lake-level fluctuations of Daihai. Reconstructed lake-level variations during the early and mid-Holocene were constructed based on 22 quartz optical stimulated luminescence (OSL) ages from six well-preserved profiles around Daihai Basin. Our results indicated Daihai showed a relatively low level at 10.2 ka, and a gradually increasing lake level following the enhanced monsoon precipitation during the mid-Holocene. Specifically, the high lake level began to develop at 8.1 ka and reached the maximum at 5.2 ka, with ∼40 m higher than present. At this time, the lake area expanded to ∼400 km2, approximately six times as large as that of present, corresponding to the maximum monsoon precipitation and intensity of EASM during the mid-Holocene. However, our stratigraphic records showed a part of the depositional records in the north and east of the Daihai was missed after 5.2 ka, probably indicating a sudden drop of the Daihai lake level. These rapid level fluctuations were likely to be interpreted by some local scenarios and need to be further investigated in the future. Overall, the lake-level fluctuation of Daihai during the early and mid-Holocene was slightly different from that observed in the previously published regional records. Possibly, the interaction of the EASM and regional feedback from topography, and hydrology factors might have contributed to the spatial complexity and distinction.

scholarly journals Variations in water level and glacier mass balance in Nam Co lake, Nyainqentanglha range, Tibetan Plateau, based on ICESat data for 2003-09

2014 ◽  
Vol 55 (66) ◽  
pp. 239-247 ◽  
Author(s):  
Hongbo Wu ◽  
Ninglian Wang ◽  
Xi Jiang ◽  
Zhongming Guo
Keyword(s):  
Tibetan Plateau ◽  
Mass Balance ◽  
Water Level ◽  
Lake Level ◽  
Altimeter Data ◽  
Glacier Mass Balance ◽  
Lake Area ◽  
Nam Co ◽  
Glacier Meltwater ◽  
Nam Co Lake

AbstractWater level fluctuations of inland lakes are related to regional-scale climate changes, and reflect variations in evaporation, precipitation and glacier meltwater flowing into the lake area in its catchment. In this paper, Ice, Cloud and land Elevation Satellite (ICESat) altimeter data and Landsat imagery (2002-09) are used to estimate Nam Co lake (Nyainqentanglha range, Tibetan Plateau) water elevation changes during 2002-09. In 2003 Nam Co lake covered an area of ~1998.8 ± 4.2 km2 and was situated at 4723 m a.s.l. Over such inland water bodies, ICESat altimeter data offer both wide coverage and spatial and temporal accuracy. We combine remote-sensing and GIS technology to map and reconstruct lake area and increased volume changes during a 7 year time series. Nam Co lake water level increased by 2.4±0.12m (0.33ma–1) between 23 February 2003 and 1 October 2009, and lake volume increased by 4.9 ±0.5 km3. In the past 7 years, Nam Co lake area has increased from 1998.78 ±5.4 to 2023.8 ±3.4 km2, the glacier-covered area has decreased from 832.34 to 821.0 km2 and the drainage basin area has decreased from 201.1 ±4.2 to 196.1 ±2.3 km2. However, the most spectacular feature is the continual water level rise from 2003 to 2009 without an obvious associated increase in precipitation. Based on digital elevation models (DEMs) from Shuttle Radar Topography Mission (SRTM) DEM data and corrected ICESat elevation data, significant changes to glacier mass balance in the western Nyainqentanglha mountains are indicated. Nyainqentanglha mountain glacier surface elevations decreased by 8.39 ± 0.45 m during 2003-09. Over the same period, at least 1.01 km3 of glacial meltwater flowed into Nam Co lake, assuming a glacial runoff coefficient of 0.6. The mean glacier mass-balance value is -490mmw.e. over the corresponding period, indicating that glacier meltwater in the catchment contributes to lake level rise. The contribution rate of glacial meltwater to lake water volume rise is 20.75%. The temporal lake level fluctuation correlates with temperature variations over the same time span.

scholarly journals A major hydrobiological change in Dasht-e Arjan Wetland (southwestern Iran) during the late glacial – early Holocene transition revealed by subfossil chironomids

2019 ◽  
Vol 56 (8) ◽  
pp. 848-856
Author(s):  
Cyril Aubert ◽  
Morteza Djamali ◽  
Matthew Jones ◽  
Hamid Lahijani ◽  
Nick Marriner ◽  
...  
Keyword(s):  
Lake Level ◽  
Regional Scale ◽  
Younger Dryas ◽  
Late Glacial ◽  
Early Holocene ◽  
Geochemical Data ◽  
The Holocene ◽  
Chironomus Plumosus ◽  
Subfossil Chironomids ◽  
Southwestern Iran

The late glacial – early Holocene transition is a key period in the earth’s history. However, although this transition is well studied in Europe, it is not well constrained in the Middle East and palaeohydrological records with robust chronologies remain scarce from this region. Here we present an interesting hydrobiological record showing a major environmental change occurring in the Dasht-e Arjan Wetland (southwestern Iran, near to Persepolis) during the late glacial – early Holocene transition (ca. 11 650 years cal BP). We use subfossil chironomids (Insecta: Diptera) as a proxy for hydrological changes and to reconstruct lake-level fluctuations. The Arjan wetland was a deep lake during the Younger Dryas marked by a dominance of Chironomus plumosus/anthracinus-type, taxa adapted to anoxic conditions of deep waters. At the beginning of the Holocene, a drastic decrease (more than 80% to less than 10%) of Chironomus plumosus/anthracinus-type, combined with diversification of littoral taxa such as Polypedilum nubeculosum-type, Dicrotendipes nervosus-type, and Glyptotendipes pallens-type, suggests a lake-level decrease and a more vegetalized aquatic environment. We compare and contrast the chironomid record of Arjan with a similar record from northwestern Iran. The palaeoclimatic significance of the record, at a local and regional scale, is subsequently discussed. The increase in Northern Hemisphere temperatures, inferred by geochemical data from NGRIP, at the beginning of the Holocene best explains the change from the Younger Dryas highstand to early Holocene lowstand conditions in the Dasht-e Arjan wetland. However, a contribution of the meltwater inflow from small local glaciers in the catchment basin is not excluded.

Charophyte Population Dynamics during the Late Quaternary at Lake Bibersee, Switzerland

1999 ◽  
Vol 47 (3) ◽  
pp. 315 ◽  
Author(s):  
Jean Nicolas Haas
Keyword(s):  
Bronze Age ◽  
Lake Level ◽  
Climatic Factors ◽  
Late Quaternary ◽  
Prehistoric Agriculture ◽  
The Holocene ◽  
Ph Values ◽  
Middle Bronze Age ◽  
The Town ◽  
Boreal Period

Oospores of 11 charophyte species were found in the Late Quaternary gyttja deposits of Lake Bibersee near the town of Zug. Except for the Boreal period rarely more than three different species were growing simultaneously during the Holocene. This compares well to typical Characeae lakes of the same size today, and shows that considerable changes in the hydrophyte diversity have taken place through time. During the first part of the Holocene the lake was oligotrophic and the species composition was mainly regulated by lake-level fluctuations due to climatic factors. During the younger periods of the Holocene the lake became mesotrophic, and pH values were for a longer period slightly alkaline. During the Early to Middle Bronze Age (1900–1400 BC) the considerable alterations in the hydrophyte composition and the simultaneous extensive prehistoric agriculture on the fertile shores of the lake point to human impact as the primary cause for changes in charophyte diversity.

A 45 kyr laminae record from the Dead Sea: Implications for basin erosion and floods recurrence

2020 ◽  
Author(s):  
Nicolas Waldmann ◽  
Yin Lu ◽  
Revital Bookman ◽  
Shmulik Marco
Keyword(s):  
High Frequency ◽  
Lake Level ◽  
Dead Sea ◽  
Last Deglaciation ◽  
The Holocene ◽  
Lamina Thickness ◽  
The Last Deglaciation ◽  
The Dead ◽  
Basin Erosion ◽  
The Last Glacial

<p>Recording and analyzing how climate change impacts flood recurrence, basin erosion, and sedimentation can improve our understanding of these systems. The aragonite-detritus laminae couplets comprising the lacustrine formations that were deposited in the Dead Sea Basin are considered as faithful monitors of the freshwater supply to the lakes. We count a total of ~5600 laminae couplets deposited in the last 45 kyr (MIS3-MIS1) at the Dead Sea depocenter, which encompass the upper 141.6 m of the ICDP Core 5017-1. The present study shows that aragonite and detritus laminae are thinner and occur at high frequency during MIS 3-2, while they are much thicker and less frequent during MIS 1. By analyzing multiple climate-connected factors, we propose that significant lake-level drops, enhanced dust input, and low vegetative cover in the drainage basin during the last deglaciation (22-11.6 ka) have considerably increased erodible materials in the Dead Sea watershed. We find a decoupling existed between the significant lake-level drop/lake size reduction and lamina thickness change during the last deglaciation. We argue that during the last glacial and the Holocene, the variation of lamina thickness at the multiple-millennium scale was not controlled directly by the lake-level/size change. We interpret this decoupling implying the transport capacity of flash-floods is low and might be saturated by the oversupply of erodible materials, and indicating a transport-limited regime during the time period. We suggest that the observed thickness and frequency distribution of aragonite-detritus laminae points to the high frequency of small-magnitude floods during the last glacial period, in contrast to low frequency, but large-magnitude floods during the Holocene.</p>

scholarly journals Diatom Stratigraphy of FA-1 Core, Qarun Lake, Records of Holocene Environmental and Climatic Change in Faiyum Oasis, Egypt

2017 ◽  
Vol 34 (1) ◽  
pp. 61-69 ◽  
Author(s):  
Abdelfattah A. Zalat ◽  
Leszek Marks ◽  
Fabian Welc ◽  
Alaa Salem ◽  
Jerzy Nitychoruk ◽  
...  
Keyword(s):  
Lake Level ◽  
Late Holocene ◽  
Distribution Patterns ◽  
Climatic Conditions ◽  
Anthropogenic Activity ◽  
Diatom Assemblages ◽  
The Holocene ◽  
Arid Conditions ◽  
Diatom Stratigraphy ◽  
Early And Middle Holocene

Abstract This study evaluates changes in the environmental and climatic conditions in the Faiyum Oasis during the Holocene based on diatom analyses of the sediment FA-1 core from the southern seashore of the Qarun Lake. The studied FA-1 core was 26 m long and covered the time span ca. 9.000 cal. yrs BP. Diatom taxa were abundant and moderately to well-preserved throughout the core sediments. Planktonic taxa were most abundant than the benthic and epiphytic forms, which were very rare and sparsely distributed. The most dominant planktonic genera were Aulacoseira and Stephanodiscus followed by frequently distribution of Cyclostephanos and Cyclotella species. The stratigraphic distribution patterns of the recorded diatoms through the Holocene sediments explained five ecological diatom groups. These groups represent distinctive environmental conditions, which were mainly related to climatic changes through the early and middle Holocene, in addition to anthropogenic activity during the late Holocene. Comparison of diatom assemblages in the studied sediment core suggests that considerable changes occurred in water level as well as salinity. There were several high stands of the freshwater lake level during humid, warmer-wet climatic phases marked by dominance of planktonic, oligohalobous and alkaliphilous diatoms alternated with lowering of the lake level and slight increases in salinity and alkalinity during warm arid conditions evident by prevalence of brackish water diatoms.

ULVS XVIII: The Quaternary Geomorphology and Calcretes of the Area around Gasr Banat in the Pre-desert of Tripolitania

1987 ◽  
Vol 18 ◽  
pp. 15-27 ◽  
Author(s):  
D. D. Gilbertson ◽  
C. O. Hunt ◽  
D. J. Briggs ◽  
G. M. Coles ◽  
N. M. Thew
Keyword(s):  
Thin Section ◽  
Quaternary Geology ◽  
Archaeological Remains ◽  
The Holocene ◽  
Aeolian Deposits ◽  
Slope Deposits ◽  
Barchan Dunes ◽  
Quaternary Geomorphology ◽  
Surficial Deposits ◽  
Holocene Period

AbstractThis paper describes the Quaternary geology of the area around Gasr Banat which lies near the confluence of the Wadis N'f'd and N'fed in the pre-desert of Tripolitania. The site is of interest because of its aridity, the notable archaeological remains that occur in the region and the opportunity it offered to map the surficial deposits of an area otherwise largely unknown. The survey revealed that two Pleistocene cobble and gravel units laid down by ‘torrential’ rivers could be distinguished: the older of which had been cemented by calcrete. Polyphase slope deposits occur. Thin section studies of the calcrete suggests it is possible to recognise two arid and two humid episodes from its micromorphology.The Holocene period is represented by water-lain and aeolian deposits on the wadi floodplain, and climbing and barchan dunes on the adjacent hills. The period immediately prior to the construction of major cross wadi barrages may have been characterised by larger or more frequent floods than occurred immediately prior to the 1984 survey; the palaeoclimatic significance of this observation is unclear. One major barrage in the area is shown to have been built on substantial earth foundations. The assumed Romano-Libyan date of these barrages still remains to be proven, but, conversely, it is now demonstrated that they were not constructed or reconstructed in the 1950s.

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