scholarly journals The glaciogenic origin of the Pleistocene calcareous dust in Argentina on the basis of field, mineralogical, textural, and geochemical analyses

2018 ◽  
Vol 91 (1) ◽  
pp. 218-233 ◽  
Author(s):  
Thea Vogt ◽  
Norbert Clauer ◽  
Isabelle Techer
Keyword(s):  
Sea Level ◽  
Soil Horizon ◽  
Field Observations ◽  
Radiocarbon Dates ◽  
Upper Pleistocene ◽  
Central Argentina ◽  
Chemical Signatures ◽  
Geochemical Analyses ◽  
Host Sediment

AbstractCalcareous dust occurs in Argentina as layers and pockets closely associated with Pleistocene deposits and periglacial features from southernmost Patagonia to at least the Mendoza Precordillera and has been traditionally interpreted as a soil horizon resulting from postdepositional pedogenesis during interglacials. Detailed field and microscopic observations and sedimentological and geochemical analyses of more than 100 samples collected from lower to upper Pleistocene deposits between 51°S and 33°S and from near sea level to 2800 m asl allow us to interpret the dust as synchronous with the host sediment. All observations and analyses lead us to conclude that: (1) the cryogenic morphology and the chemical signatures of the calcite component show that the dust is glaciogenic, (2) the dust was carried by southeasterly Antarctic winds, and (3) it was deposited over most of southern and central Argentina. Field observations, geomorphic evidence, and radiocarbon dates suggest that the dust was deposited during several Pleistocene glacial episodes.

The geochemical stratigraphy, field relations and temporal variation of the Mull–Morvern Tertiary lava succession, NW Scotland

1995 ◽  
Vol 86 (1) ◽  
pp. 35-47 ◽  
Author(s):  
Andrew Craig Kerr
Keyword(s):  
Sea Level ◽  
Main Part ◽  
Volcanic Ash ◽  
Lava Flows ◽  
Field Observations ◽  
Continuous Section ◽  
Flow Units ◽  
Early Tertiary ◽  
The Uk ◽  
Basaltic Lavas

AbstractThe early Tertiary Mull-Morvern lava succession, NW Scotland, represents the thickest continuous section (1000 m from sea level to the top of Ben More) of Tertiary lavas exposed in the UK. This succession has been sampled and geochemically analysed, on a flow-by-flow basis, throughout the lava succession. Field observations during the course of this sampling suggest that the early lava flows (the Staffa Magma sub-Type) ponded in palaeovalleys along with interlava sediments. In the main part of the Mull lava succession (the Mull Plateau Group) the lava flows are on average ∼ 5 m thick. Most previous Hebridean workers have assumed that the red horizons commonly found between these later lava flows, represent weathered flow tops. However, this study has shown that in some places these red ‘boles’ appear to be a combination of both volcanic ash and weathered basalt.Chemically distinctive units of flows have been found throughout the succession. The two most abundant magma sub-types of the Mull Plateau Group, primitive (>9wt% MgO) basalts with Ba/Nb» 15 and more evolved (<9wt% MgO) basalts-hawaiites with Ba/Nb<15, form packets of flow units which can be up to 200 m thick. These chemically distinctive flow units have been correlated across the lava succession. However, the correlation of individual lava flows has proved difficult. The Mull Plateau Group lavas generally become more evolved and less contaminated with continental crust towards the top of the succession, culminating in the trachytes of the Pale Group on Ben More. Basaltic lavas above the Pale Group have markedly different trace element ratios, and seem to represent shallower, more extensive asthenospheric melting than the Mull Plateau Group.

scholarly journals Moscow MV Lomonosov State University Radiocarbon Dates II: Sea Level Indicators from Coastal USSR

Radiocarbon ◽  
1983 ◽  
Vol 25 (3) ◽  
pp. 892-898 ◽  
Author(s):  
N I Glushankova ◽  
O B Parunin ◽  
A O Selivanov ◽  
A I Shlukov ◽  
T A Timashkova
Keyword(s):  
Soviet Union ◽  
Sea Level ◽  
State University ◽  
Radiocarbon Dates ◽  
Sea Levels ◽  
The Soviet Union ◽  
Laboratory Results ◽  
Last Deglacial

The following list summarizes the post-1970 laboratory results of 14C dating of ancient sea-level indicators from the coasts of the Soviet Union. One of the aims of the International Geologic Correlation Programme Project No. 61 “Sea level movements during the last deglacial hemicycle” is the global cataloguing and mapping of ancient sea levels. The laboratory, which acts as the USSR National curator for these age measurements obtains dates sampled from its own expeditions and from other institutions of the country.

scholarly journals Methods of calculating landslide volume using remote sensing data

2020 ◽  
Vol 149 ◽  
pp. 02009
Author(s):  
Maira Razakova ◽  
Alexandr Kuzmin ◽  
Igor Fedorov ◽  
Rustam Yergaliev ◽  
Zharas Ainakulov
Keyword(s):  
Remote Sensing ◽  
Sea Level ◽  
Remote Sensing Data ◽  
Field Studies ◽  
Aerial Photographs ◽  
Field Observations ◽  
Sensing Data ◽  
Quantitative Estimates ◽  
Landslide Volume ◽  
Engineering Protection

The paper considers the issues of calculating the volume of the landslide from remote sensing data. The main methods of obtaining information during research are field observations. The most important results of field studies are quantitative estimates, such as the volume of the embankment resulting from a landslide, morphometric indicators, etc. The study of a remote and remote object was carried out by remote methods using aerial photographs in the Ile Alatau foothills at 1,600 meters above sea level. The obtained materials from the mudflow survey will be useful in developing solutions to mitigate the effects of disasters and in the design of measures for engineering protection from landslides.

scholarly journals Late Quaternary Deglaciation, Glaciomarine Sedimentation and Glacioisostatic Recovery in the Rivière Nastapoka Area, Eastern Hudson Bay, Northern Québec

2005 ◽  
Vol 57 (1) ◽  
pp. 65-83 ◽  
Author(s):  
Patrick Lajeunesse ◽  
Michel Allard
Keyword(s):  
Sea Level ◽  
Late Quaternary ◽  
Phase 1 ◽  
Second Phase ◽  
Hudson Bay ◽  
Silty Clay ◽  
Paleoenvironmental Reconstruction ◽  
Relative Sea Level ◽  
Radiocarbon Dates ◽  
Fluvial Terraces

Abstract This study presents a paleoenvironmental reconstruction of deglaciation dynamics and chronology, glaciomarine and postglacial sedimentation, as well as glacioisostatic recovery in the Rivière Nastapoka area, eastern Hudson Bay. Results indicate that the retreat of Québec-Labrador ice was mainly controlled by topography and was marked by four phases. Radiocarbon dates indicate that deglaciation began about 8.3 ka cal. BP and was characterized by a stillstand of the ice margin in the Nastapoka Hills that lead to the deposition of a drift belt in a high relative sea-level (Phase 1). After this stabilisation, the ice margin retreated rapidly eastward in a region of low relief and deposited a drape of silty clay in a falling relative sea-level (Phase 2). A second phase of stabilization of the ice margin lasted until at least 7.2 ka cal.BP on the higher shield peneplaine east of the limit of the Tyrrell Sea (Phase 3). This lead to the deposition of a belt of glaciofluvial deltas in a lower relative sea-level. Following this stillstand, the eastward retreat and subsequent ablation of the ice in central Québec-Labrador generated meltwater that transported large volumes of glacial sediments by fluvial processes and downcutting of fluvial terraces in previously deposited glaciofluvial and marine sediments (Phase 4). Glacioisostatic rebound reached 0.07 m/yr during the early phase of deglaciation and decreased to 0.04 m/yr between 6 and 5 ka cal. BP and 0.016 m/yr in the last 1000 years.

scholarly journals Holocene Evolution of the Outer Lake of Hwajinpo Lagoon On the Eastern Coast of Korea; Environmental Changes with Holocene Sea-Level Fluctuation of the East Sea (Sea of Japan)

Radiocarbon ◽  
2004 ◽  
Vol 46 (2) ◽  
pp. 797-808 ◽  
Author(s):  
Jong-Gwon Yum ◽  
Kang-Min Yu ◽  
Keiji Takemura ◽  
Toshiro Naruse ◽  
Akihisa Kitamura ◽  
...  
Keyword(s):  
Sea Level ◽  
Environmental Changes ◽  
River System ◽  
Eastern Coast ◽  
Estuarine System ◽  
Level Fluctuation ◽  
Radiocarbon Dates ◽  
Sedimentary Environments ◽  
Sea Level Fluctuation ◽  
Low Sulfur Content

The evolution of the outer lake of Hwajinpo Lagoon in Korea has been reconstructed using environmental proxies (lithologic, geochemical, and fossil data) with a chronology established using 7 accelerator mass spectrometry (AMS) radiocarbon dates. Grain size, water content, and X-ray analyses from the core of outer coastal lakes (HJ99) were used to reconstruct sedimentary environments by using total organic carbon, C/N, S, and C/S chemical proxies. Assemblages of mollusc remains also provided paleoenvironmental information. The environmental changes of the outer lake of Hwajinpo Lagoon can be divided into 6 depositional phases. The basin of the Hwajinpo was exposed and underwent a weathering process before the Holocene period. The muddy sand layer on the weathered bedrock indicated an estuarine system about 6000 BP. The laminated layer implies that the lagoonal system was anoxic between about 5500–2800 BP. The marl layer implies a relatively oxic lagoonal condition with mollusc presence about 2500 B P. The layer of very low sulfur content indicates a freshwater lake system isolated by a sand barrier about 1700 BP. Beginning about 1000 B P, the river system deposits progress progradation on the marl layer. Two erosional landforms could be related with a high standing sea level span during Holocene. These high-stands are dated at 5700 BP and 2200 BP and are supposed to have formed erosional landforms of about 1.6 amsl and 0.8 amsl, respectively. Environmental changes of the outer lake of Hwajinpo Lagoon are considered due mainly to the lake- and sea-level fluctuation during Holocene.

scholarly journals Repeated evolution of flightlessness in Dryolimnas rails (Aves: Rallidae) after extinction and recolonization on Aldabra

2019 ◽  
Vol 186 (3) ◽  
pp. 666-672 ◽  
Author(s):  
Julian P Hume ◽  
David Martill
Keyword(s):  
Indian Ocean ◽  
Sea Level ◽  
Upper Pleistocene ◽  
Fossil Evidence ◽  
Before And After ◽  
Repeated Evolution ◽  
The Indian Ocean

AbstractThe Aldabra rail, Dryolimnas cuvieri subsp. aldabranus, endemic to the Aldabra Atoll, Seychelles, is the last surviving flightless bird in the Indian Ocean. Aldabra has undergone at least one major, total inundation event during an Upper Pleistocene (Tarantian age) sea-level high-stand, resulting in the loss of all terrestrial fauna. A flightless Dryolimnas has been identified from two temporally separated Aldabran fossil localities, deposited before and after the inundation event, providing irrefutable evidence that a member of Rallidae colonized the atoll, most likely from Madagascar, and became flightless independently on each occasion. Fossil evidence presented here is unique for Rallidae and epitomizes the ability of birds from this clade to successfully colonize isolated islands and evolve flightlessness on multiple occasions.

A Groundwater Hypothesis for the Origin of “Fire Areas” on the Northern Channel Islands, California

1986 ◽  
Vol 26 (2) ◽  
pp. 207-217 ◽  
Author(s):  
John Cushing ◽  
Adrian M. Wenner ◽  
Elmer Noble ◽  
Marla Daily
Keyword(s):  
Low Temperature ◽  
Channel Islands ◽  
Field Observations ◽  
Human Origin ◽  
X Ray Diffraction ◽  
Radiocarbon Dates ◽  
X Ray ◽  
The Past ◽  
Northern Channel Islands ◽  
In Fire

Pleistocene areas of red sediments and carbonized vegetation on the Northern Channel Islands, California, have in the past been interpreted as caused by fires of either natural or human origin. Some are associated with darkened mammoth and bird fossils, and these fossils have been considered as having been burned by early man. Reevaluation of these so-called “fire areas” indicates that the above phenomena are the result of low-temperature (≤100°C), nonheating processes occurring in groundwater. Evidence for this conclusion is derived from field observations on fossil carbonized vegetation, and the geology of the areas. Additional evidence derives from experiments on the red sediments and fossil wood, X-ray diffraction analyses, magnetic analyses, studies on the clay minerals smectite and illite, and the demonstration that fossil mammoth bone contains sufficient Fe and Mn to account for their discoloration. Much of the carbonization of vegetation probably occurred in water rather than in fire. Radiocarbon dates from the islands will probably need to be reevaluated. These data provide evidence contrary to the concept of the occurrence of significant fires, either natural or set by early man, on the Northern Channel Islands.

scholarly journals Relative sea-level changes in crete: reassessment of radiocarbon dates from Sphakia and west Crete

2002 ◽  
Vol 97 ◽  
pp. 171-200 ◽  
Author(s):  
Simon Price ◽  
Tom Higham ◽  
Lucia Nixon ◽  
Jennifer Moody
Keyword(s):  
Sea Level ◽  
Late Antiquity ◽  
Isotopic Fractionation ◽  
Sea Level Changes ◽  
Relative Sea Level ◽  
Radiocarbon Dates ◽  
Sea Levels ◽  
Catastrophic Earthquake ◽  
Radiocarbon Data ◽  
Calendar Dates

This article is concerned with the recognition and dating of Holocene relative sea-level changes along the coast of west Crete (an island located in the active Hellenic subduction arc of the southern Aegean) and in particular in Sphakia. Radiocarbon data for changes in sea levels collected and analysed previously must (a) be recorrected to take into account isotopic fractionation, and (b) recalibrated by using the new marine reservoir value. These new radiocarbon dates are analysed using Bayesian statistics. The resulting calendar dates for changes in sea level are younger than previously assumed. In particular the Great Uplift in western Crete in late antiquity must be dated to the fifth or sixth century AD, not to AD 365. Moreover, recent work on tectonics suggests that the Great Uplift need not have been accompanied by a catastrophic earthquake. Finally, we consider the consequences of the Great Uplift for some coastal sites in Sphakia.

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