scholarly journals Development of Solontsovskie Lakes as indicator of humidity within Central Sikhote-Alin in the Late Holocene

2021 ◽  
Vol 5 (3) ◽  
pp. 287-304
Author(s):  
N.G. Razjigaeva ◽  
◽  
L.A. Ganzey ◽  
T.A. Grebennikova ◽  
T.A. Kopoteva ◽  
...  
Keyword(s):  
Late Holocene ◽  
Hydrological Regime ◽  
Taxonomic Composition ◽  
Climatic Conditions ◽  
Ice Age ◽  
Sikhote Alin ◽  
Frequent Change ◽  
Radiocarbon Dates ◽  
Trophic Preferences ◽  
Middle Mountains

The stages of development of small Solontsovskie (Shanduyskie) Lakes located in the middle mountains of the Central Sikhote-Alin within large landslides, formed on the slopes of the paleovolcano, are identified on the basis of complex study of the sediment section of the Nizhnee Lake. The ecological-taxonomic composition of the diatom flora, the botanical composition of peat have been analyzed, and the tendencies of lacustrine sedimentation depending on the different scale of hydroclimatic changes in the Late Holocene have been established. The age model is based on 6 radiocarbon dates. The temporary resolution for the reconstructions is 30–60 years. A comparison of the development of Nizhnee and Izyubrinye Solontsi Lakes was carried out, the stages of watering and shallowing of lakes were identified on the basis of their dynamics, which made it possible to restore the change in moisture in the middle mountains. Organogenic deposits in lacustrine basins accumulated at high rates (up to 1.7–1.9 mm/ year). The most detailed data were obtained for the last 2.6 thousand cal. yr BP based on the study of the sediment section of the Nizhnee Lake, which responded more sensitively to changing climatic conditions. Frequent changes in diatom assemblages and peat-forming plants indicate unstable hydroclimatic conditions with varying degrees of watering and drainage up to complete overgrowth of water bodies. According to the data of diatom analysis, a successive change in the trophicity of the lake was traced. A frequent change of sphagnum mosses of different sections with different trophic preferences was established. The main reason for the change in the hydrological regime of the lakes was variations in precipitation during the short-term climatic changes. The correlation of the identified paleoclimatic events with global data has been carried out. Cooling periods, as a rule, were accompanied by a decrease in moisture, but the Little Ice Age was wet due to an increase in precipitation.

scholarly journals Paleoflood records within Sikhote-Alin foothills during last 2.2 ka

2019 ◽  
pp. 85-99
Author(s):  
N. G. Razzhigaeva ◽  
L. A. Ganzey ◽  
T. A. Grebennikova ◽  
T. A. Kopoteva ◽  
M. A. Klimin ◽  
...  
Keyword(s):  
Little Ice Age ◽  
Heavy Rainfall ◽  
Late Holocene ◽  
River Flow ◽  
Ash Content ◽  
Ice Age ◽  
Peat Bog ◽  
Sikhote Alin ◽  
Radiocarbon Dates ◽  
Mineral Components

The periods of intensification of the frequency of severe floods in Late Holocene were reconstructed on the basis of a multi-proxy study of the section of paleo-bend deposits in the lower reaches of the Bikin River, which includes a peat bog, buried by floodplain loam. The peat bog was formed on the place of flood lake and is represented by interlayering of the layers with a different contents of mineral components, which brought during heavy floods. The criteria for the allocation of phases of abundant river flow were defined. Peat ash content, biostratigraphic data (diatom, botanical analyzes) and radiocarbon dates of the peat bog showed that the flood activity in the foothills of the Sikhote-Alin changed significantly over the last 2.24 ka. The most severe floods occurred in the Medieval Warm Period and warm phases of the Little Ice Age. Duration of periods with strong floods varied from 70 to 200 years. Synoptic situations leading to heavy rainfall were probably similar to modern ones. Strong floods began last 210 yr in the conditions of a trend for warming. Reduction of flood activity, as a rule, occurred in cooling. The intensification of fires took place in drier periods. The response of swamp landscapes to the passage of severe floods and fires has been established.

Unstable Climate Oscillations during the Late Holocene in the Eastern Bransfield Basin, Antarctic Peninsula

2002 ◽  
Vol 58 (3) ◽  
pp. 234-245 ◽  
Author(s):  
Boo-Keun Khim ◽  
Ho Il Yoon ◽  
Cheon Yun Kang ◽  
Jang Jun Bahk
Keyword(s):  
Antarctic Peninsula ◽  
Late Holocene ◽  
Accumulation Rate ◽  
Silica Content ◽  
Climatic Conditions ◽  
Ice Age ◽  
Geochemical Data ◽  
Sediment Properties ◽  
Bransfield Basin ◽  
Distinct Features

AbstractCore A9-EB2 from the eastern Bransfield Basin, Antarctic Peninsula, consists of pelagic (diatom ooze-clay couplets and bioturbated diatom ooze) and hemipelagic (bioturbated mud) sediments interbedded with turbidites (homogeneous mud and silt–clay couplets). The cyclic and laminated nature of these pelagic sediments represents alternation between the deposition of diatom-rich biogenic sediments and of terrigenous sediments. Sediment properties and geochemical data explain the contrasting lamination, with light layers being finer-grained and relatively rich in total organic carbon and biogenic silica content. Also, the high-resolution magnetic susceptibility (MS) variations highlight distinct features: high MS values coincide with clastic-rich sections and low MS values correspond to biogenic sections. The chronology developed for core A9-EB2 accounts for anomalous ages associated with turbidites and shows a linear sedimentation rate of approximately 87 cm/103 yr, which is supported by an accumulation rate of 80 cm/103 yr calculated from 210Pb activity. The late Holocene records clearly identify Neoglacial events of the Little Ice Age (LIA) and Medieval Warm Period (MWP). Other unexplained climatic events comparable in duration and amplitude to the LIA and MWP events also appear in the MS record, suggesting intrinsically unstable climatic conditions during the late Holocene in the Bransfield Basin of Antarctic Peninsula.

Siliceous microfossils and mineral magnetic characteristics in a sediment core from Lake Manitoba, Canada: a remnant of glacial Lake Agassiz

1999 ◽  
Vol 36 (8) ◽  
pp. 1299-1314 ◽  
Author(s):  
Jan Risberg ◽  
Per Sandgren ◽  
James T Teller ◽  
William M Last
Keyword(s):  
Great Plains ◽  
Late Holocene ◽  
Climatic Conditions ◽  
Glacial Lake ◽  
Magnetic Characteristics ◽  
Northern Great Plains ◽  
Silty Clay ◽  
Lake Agassiz ◽  
Radiocarbon Dates ◽  
Glacial Lake Agassiz

A 14.2 m long core was recovered from the southern Lake Manitoba basin. The sediment, consisting mainly of silty clay, was studied for siliceous microfossil content and mineral magnetics; 14 new accelerator mass spectrometry (AMS) radiocarbon dates provide chronological control of the paleoenvironmental history of the basin. The basal 5 m contains ice-rafted clasts and is largely barren of siliceous microfossils; these sediments were deposited when the lake was part of glacial Lake Agassiz. Sediments immediately overlying the barren part of the sequence contain AMS dates of 7700-7400 BP and reflect a dramatic change in conditions in the basin. Diatom abundances rise abruptly. Magnetic characteristics change substantially. The presence of freshwater taxa such as Stephanodiscus niagarae, together with brackish water diatoms, indicate that shallow, turbid, high-nutrient conditions with variable salinity occurred during the early part of the middle Holocene. Although climatic conditions throughout the northern Great Plains are known to have become drier and warmer during the mid-Holocene, there is a distinct change in diatom taxa in the Lake Manitoba sequence toward less saline conditions at this time. The presence of the riverine diatom Aulacoseira granulata in this interval supports previous conclusions that these freshwater conditions resulted from the northward diversion of the Assiniboine River into the basin. Following this, diatoms indicate an abrupt increase in salinity to >1500 mg·L-1 total dissolved solids between 4000 and 2600 BP, reflecting the diversion of the fresh waters of the Assiniboine River away from Lake Manitoba. Increasingly cooler and wetter conditions during the late Holocene, combined with differential isostatic rebound, caused a freshening of the lake during the late Holocene.

scholarly journals Small glaciers disappearing in the tropical Andes: a case-study in Bolivia: Glaciar Chacaltaya (16o S)

2001 ◽  
Vol 47 (157) ◽  
pp. 187-194 ◽  
Author(s):  
Edson Ramírez ◽  
Bernard Francou ◽  
Pierre Ribstein ◽  
Marc Descloitres ◽  
Roger Guérin ◽  
...  
Keyword(s):  
Surface Area ◽  
Hydrological Regime ◽  
High Elevation ◽  
Climatic Conditions ◽  
Ice Age ◽  
Tropical Andes ◽  
Equilibrium Line Altitude ◽  
La Paz ◽  
Ground Penetrating ◽  
Near Future

AbstractGlaciar Chacaltaya is an easily accessible glacier located close to La Paz, Bolivia. Since 1991, information has been collected about the evolution of this glacier since the Little Ice Age, with a focus on the last six decades. The data considered in this study are monthly mass-balance measurements, yearly mappings of the surface topography and a map of the glacier bed given by ground-penetrating radar survey. A drastic shrinkage of ice has been observed since the early 1980s, with a mean deficit about 1 m a−1 w.e. From 1992 to 1998, the glacier lost 40% of its average thickness and two-thirds of its total volume, and the surface area was reduced by >40%. With a mean estimated equilibrium-line altitude lying above its upper reach, the glacier has been continuously exposed to a dominant ablation on the whole surface area. If the recent climatic conditions continue, a complete extinction of this glacier in the next 15 years can be expected. Glaciar Chacaltaya is representative of the glaciers of the Bolivian eastern cordilleras, 80% of which are small glaciers (<0.5 km2). A probable extinction of these glaciers in the near future could seriously affect the hydrological regime and the water resources of the high-elevation basins.

Late Glacial and Late Holocene Moraines in the Cerros Cuchpanga, Central Peru

1984 ◽  
Vol 21 (3) ◽  
pp. 275-285 ◽  
Author(s):  
H.E. Wright
Keyword(s):  
Little Ice Age ◽  
Late Holocene ◽  
Late Glacial ◽  
Ice Age ◽  
Recent Past ◽  
Valley Bottom ◽  
Radiocarbon Dates ◽  
Western Cordillera ◽  
Limestone Bedrock ◽  
Ice Field

Small ice fields on the western cordillera northeast of Lima were expanded to three times their present size in the recent past, and the regional snow line was probably about 100 m lower than it is today. Outwash from the expanded glaciers formed deltas of silt in valley-bottom lakes. When the ice lobes retreated, the reduced outwash was trapped behind recessional moraines, and the clear meltwater infiltrated into the limestone bedrock and emerged at the heads of the deltas in spring pools. The delta surfaces then became covered with peat, and radiocarbon dates for the base of the peat (1100 ± 70 and 430 ± 70 yr B.P. for two different deltas) indicate that the maximum ice advance was older than those dates and, thus, older than the Little Ice Age of many north-temperate regions. Much older moraines date from expansion of the same local summit glaciers to even lower levels in the main valleys, which had previously been inundated by the cordilleran ice field. The cordilleran deglaciation and this expansion of local glaciers probably occurred between 12,000 and 10,000 yr ago, on the basis of slightly contradictory radiocarbon dates.

Modern and past periglacial features in Central Asia and their implication for paleoclimate reconstructions

2015 ◽  
Vol 40 (3) ◽  
pp. 369-391 ◽  
Author(s):  
Frank Lehmkuhl
Keyword(s):  
Central Asia ◽  
Late Holocene ◽  
Large Degree ◽  
Climatic Conditions ◽  
Ice Age ◽  
Soil Humidity ◽  
Air Temperatures ◽  
Rock Glaciers ◽  
Ice Wedge ◽  
Moisture Conditions

In the continental areas of Central and High Asia, periglacial landform assemblages, sediment structures and processes are mainly influenced and determined by of soil humidity during freeze–thaw cycles. These cryogenic processes result in periglacial landforms such as solifluction, earth hummocks or patterned ground. The distribution of rock glaciers as clear indicators of permafrost is additionally determined by rock fall or moraine debris composed of large boulders (e.g. of granite). Periglacial features were used to reconstruct past climatic conditions, e.g. relict involutions and ice-wedge casts provide evidence for the distribution of former permafrost, say, for the Last Glacial Maximum (LGM). Past temperatures, e.g. mean annual air temperatures, can be estimated from these periglacial features and can be compared with other proxy data, such as glacier fluctuations. Examples from late Holocene solifluction activity in the Altai, Khangai and north-eastern Tibetan Plateau show a different intensity of solifluction processes during the late Holocene and Little Ice Age due to a decrease in temperature and higher soil humidity. The distribution of past permafrost in some regions is still a matter of debate because of different interpretations of sediment structures: sometimes features described as ice-wedge casts may be caused by roots or desiccation cracks due to drying of clay rich sediments. Seismically deformed unconsolidated deposits (seismites) can also be misinterpreted as periglacial involutions. The lack of certain landform assemblages and sediment structures does not necessarily mean that the area had no permafrost. Moisture conditions can also determine the periglacial landform generation to a large degree. They can be ordered in Central Asia as follows (from highest moisture availability to lowest): solifluction; rock glacier; permafrost involutions; ice-wedge casts; sand-wedge casts.

Holocene sedimentary architecture and paleoclimate variability at Mono Lake, California

2019 ◽  
Author(s):  
S.R.H. Zimmerman ◽  
S.R. Hemming ◽  
S.W. Starratt
Keyword(s):  
Sierra Nevada ◽  
Lake Level ◽  
Late Holocene ◽  
Mono Lake ◽  
Ice Age ◽  
Historical Period ◽  
Radiocarbon Dates ◽  
The Core ◽  
Sedimentary Architecture ◽  
Lake Floor

ABSTRACT Mono Lake occupies an internally drained basin on the eastern flank of the Sierra Nevada, and it is sensitive to climatic changes affecting precipitation in the mountains (largely delivered in the form of snowpack). Efforts to recover cores from the lake have been impeded by coarse tephra erupted from the Mono Craters, and by disruption of the lake floor due to the uplift of Paoha Island ~300 yr ago. In this study, we describe the stratigraphy of cores from three recent campaigns, in 2007, 2009, and 2010, and the extents and depths of the tephras and disturbed sediments. In the most successful of these cores, BINGO-MONO10-4A-1N (BINGO/10-4A, 2.8 m water depth), we used core stratigraphy, geochemistry, radiocarbon dates, and tephrostratigraphy to show that the core records nearly all of the Holocene in varying proportions of detrital, volcanic, and authigenic sediment. Both the South Mono tephra of ca. 1350 cal yr B.P. (calibrated years before A.D. 1950) and the 600-yr-old North Mono–Inyo tephra are present in the BINGO/10-4A core, as are several older, as-yet-unidentified tephras. Laminated muds are inferred to indicate a relatively deep lake (³10 m over the core site) during the Early Holocene, similar to many records across the region during that period. The Middle and Late Holocene units are more coarsely bedded, and coarser grain size and greater and more variable amounts of authigenic carbonate detritus in this interval are taken to suggest lower lake levels, possibly due to lower effective wetness. A very low lake level, likely related to extreme drought, is inferred to have occurred sometime between 3500 and 2100 cal yr B.P. This interval likely corresponds to the previously documented Marina Low Stand and the regional Late Holocene Dry Period. The BINGO/10-4A core does not preserve a complete record of the period encompassing the Medieval Climate Anomaly, the Little Ice Age, and the historical period, probably due to erosion because of its nearshore position.

scholarly journals Population collapse in Congo rainforest from 400 CE urges reassessment of the Bantu Expansion

2021 ◽  
Vol 7 (7) ◽  
pp. eabd8352
Author(s):  
Dirk Seidensticker ◽  
Wannes Hubau ◽  
Dirk Verschuren ◽  
Cesar Fortes-Lima ◽  
Pierre de Maret ◽  
...  
Keyword(s):  
Human Activity ◽  
Climatic Conditions ◽  
Radiocarbon Dates ◽  
Expansion Phase ◽  
Bantu Languages ◽  
Population Collapse ◽  
Early Stages ◽  
Linguistic Evidence ◽  
Spread Model ◽  
Migration Event

The present-day distribution of Bantu languages is commonly thought to reflect the early stages of the Bantu Expansion, the greatest migration event in African prehistory. Using 1149 radiocarbon dates linked to 115 pottery styles recovered from 726 sites throughout the Congo rainforest and adjacent areas, we show that this is not the case. Two periods of more intense human activity, each consisting of an expansion phase with widespread pottery styles and a regionalization phase with many more local pottery styles, are separated by a widespread population collapse between 400 and 600 CE followed by major resettlement centuries later. Coinciding with wetter climatic conditions, the collapse was possibly promoted by a prolonged epidemic. Comparison of our data with genetic and linguistic evidence further supports a spread-over-spread model for the dispersal of Bantu speakers and their languages.

Tree line shifts, changing vegetation assemblages and permafrost dynamics on Galdhøpiggen (Jotunheimen, Norway) over the past ~4400 years

The Holocene ◽  
2021 ◽  
pp. 095968362110665
Author(s):  
Helen Hallang ◽  
Cynthia A Froyd ◽  
John F Hiemstra ◽  
Sietse O Los
Keyword(s):  
Scots Pine ◽  
Late Holocene ◽  
Accumulation Rate ◽  
Climatic Changes ◽  
Climatic Conditions ◽  
Tree Line ◽  
Peat Core ◽  
Modern Pollen ◽  
Modern Analogue ◽  
Downy Birch

An environmental reconstruction based on palynological evidence preserved in peat was carried out to examine late-Holocene alpine tree line dynamics in the context of past climatic changes on Galdhøpiggen (Jotunheimen, southern Norway). We analysed a peat core taken from a mire at the present-day tree line (1000 m a.s.l.), c. 450 m downslope from the lower limit of sporadic permafrost. We adopted a combination of commonly used indicators of species’ local presence to reconstruct past vegetation assemblages, such as the relative pollen abundance (%), pollen accumulation rate (PAR), and presence of indicator species. Additionally, fossil pollen from the peat sequence was compared to modern pollen from a surface moss polster to establish a modern analogue. The results were compared with studies covering the late-Holocene climatic changes in the area. The reconstruction demonstrates that a pine-dominated woodland reached above the present-day tree line at c. 4300 cal. yr BP, suggesting a warmer climate suitable for Scots pine ( Pinus sylvestris) growth at this altitude. Scots pine retreated to lower altitudes between c. 3400 and 1700 cal. yr BP, accompanied by the descent of the low-alpine shrub-dominated belt, in response to cooling climatic conditions. The colder period covered c. 1700–170 cal. yr BP, and an open downy birch ( Betula pubescens) woodland became widespread at 1000 m a.s.l., whilst pine remained sparse at this altitude. From c. 170 cal. yr BP onwards, warming allowed pine to re-establish its local presence alongside downy birch at 1000 m a.s.l.

scholarly journals FAME (v1.0): a simple module to simulate the effect of planktonic foraminifer species-specific habitat on their oxygen isotopic content

2018 ◽  
Vol 11 (9) ◽  
pp. 3587-3603 ◽  
Author(s):  
Didier M. Roche ◽  
Claire Waelbroeck ◽  
Brett Metcalfe ◽  
Thibaut Caley
Keyword(s):  
Late Holocene ◽  
Simple Module ◽  
Climatic Conditions ◽  
Model Data ◽  
Planktonic Foraminifer ◽  
Planktonic Foraminifers ◽  
Oxygen Isotopic ◽  
Species Specific ◽  
Almost All ◽  
Multiproxy Approach

Abstract. The oxygen-18 to oxygen-16 ratio recorded in fossil planktonic foraminifer shells has been used for over 50 years in many geoscience applications. However, different planktonic foraminifer species generally yield distinct signals, as a consequence of their specific living habitats in the water column and along the year. This complexity is usually not taken into account in model–data integration studies. To overcome this shortcoming, we developed the Foraminifers As Modeled Entities (FAME) module. The module predicts the presence or absence of commonly used planktonic foraminifers and their oxygen-18 values. It is only forced by hydrographic data and uses a very limited number of parameters, almost all derived from culture experiments. FAME performance is evaluated using the Multiproxy Approach for the Reconstruction of the Glacial Ocean surface (MARGO) Late Holocene planktonic foraminifer calcite oxygen-18 and abundance datasets. The application of FAME to a simple cooling scenario demonstrates its utility to predict changes in planktonic foraminifer oxygen-18 to oxygen-16 ratio in response to changing climatic conditions.

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