Late Quaternary volcanic ash in the peatlands of central Alberta

1989 ◽  
Vol 26 (2) ◽  
pp. 207-214 ◽  
Author(s):  
S. C. Zoltai
Keyword(s):  
Volcanic Ash ◽  
Late Quaternary ◽  
Middle Layer ◽  
Accumulation Rates ◽  
Peat Accumulation ◽  
Peat Deposits ◽  
Volcanic Events ◽  
Before And After ◽  
Aerial Deposition

Three distinct volcanic-ash layers were identified in peat deposits through visual, microscopic, and chemical means. These layers were related to known volcanic events through the 14C dating of 34 peat samples. The upper layer was probably Bridge River ash, deposited about 2350 years BP. The middle layer was possibly St. Helens Y tephra, deposited around 3400 years BP. The lower ash was related to Mazama tephra, deposited about 6600 years BP. Ash-enriched layers were formed in the accumulating peat as aerial deposition of tephra occurred, often for several hundred years before and after the presumed main eruption, as shown by 14C dates and peat accumulation rates. This implies periodic eruptions by the volcanoes, not all of which produced distinct ash layers in areas distant from the source. Redeposition from wind-eroded beds of Mazama ash during the dry postglacial climatic maximum is a possibility.

scholarly journals A Late Quaternary climate record based on long-chain diol proxies from the Chilean margin

2018 ◽  
Vol 14 (11) ◽  
pp. 1783-1803 ◽  
Author(s):  
Marijke W. de Bar ◽  
Dave J. Stolwijk ◽  
Jerry F. McManus ◽  
Jaap S. Sinninghe Damsté ◽  
Stefan Schouten
Keyword(s):  
Late Quaternary ◽  
Nutrient Concentrations ◽  
Phytoplankton Production ◽  
Accumulation Rates ◽  
Last Interglacial ◽  
Climate Record ◽  
Quaternary Climate ◽  
Before And After ◽  
Mis 5 ◽  
Long Chain

Abstract. In this study we have applied different indices based on long-chain diols, i.e., the long-chain diol index (LDI) as a proxy for past SST, the diol index as an indicator of past upwelling conditions, and the nutrient diol index (NDI) as a proxy for nitrate and phosphate concentrations in seawater. The proxies were analyzed in marine sediments recovered at ODP Site 1234, located within the Peru–Chile upwelling system, with a ∼2 kyr resolution covering the last 150 kyr. We also generated TEX86H and U37K′ temperature and planktonic δ18O records, as well as total organic carbon (TOC) and accumulation rates (ARs) of TOC and lipid biomarkers (i.e., C37 alkenones, GDGTs, dinosterol, and loliolide) to reconstruct past phytoplankton production. The LDI-derived SST record covaries with TEX86H- and U37K′-derived SST records as well as with the planktonic δ18O record, implying that the LDI reflects past SST variations at this site. TOC and phytoplankton AR records indicate increased export production during the last interglacial (MIS 5), simultaneous with a peak in the abundance of preserved Chaetoceros diatoms, suggesting intensified upwelling during this period. The diol index is relatively low during the upwelling period, but peaks before and after this period, suggesting that Proboscia diatoms were more abundant before and after the period of upwelling. The NDI reveals the same trends as the diol index, suggesting that the input of nitrate and phosphate was minimal during upwelling, which is unrealistic. We suggest that the diol index and NDI should perhaps be considered as indicators for Proboscia productivity instead of upwelling conditions or nutrient concentrations.

scholarly journals Fires and volcanic activity: History of fire in the Mexico basin during late Pleistocene based on carbonized material records in the Chalco lake

2019 ◽  
Vol 36 (2) ◽  
pp. 259-269
Author(s):  
Rodrigo Martínez-Abarca ◽  
Socorro Lozano-García ◽  
Beatriz Ortega-Guerrero ◽  
Margarita Caballero-Miranda
Keyword(s):  
Volcanic Activity ◽  
Forest Fires ◽  
Particle Dispersion ◽  
Particle Analysis ◽  
Particle Model ◽  
Central Mexico ◽  
Accumulation Rates ◽  
Volcanic Events ◽  
Charcoal Particle ◽  
Before And After

Forest fires, considered as free and not programmed fire propagation, are perturbations that greatly alter ecosystems. During fires, variable quantities of charcoal particles are produced by the burning vegetation, which can be later deposited in lacustrine basins. The traditional charcoal size particle model associates the > 100 µm primary particles to local fire events, within the watershed, and the < 100 µm particles are linked to regional fire events, outside the watershed. Fires can be related with favorable climatic conditions, but in tectonically active areas like the basin of Mexico, volcanism can also be a factor producing fires and charcoal particles. We document the history, intensity and frequency of fires recorded in the lacustrine sediments of lake Chalco (core CHAVII-11), by performing a high-resolution charcoal particle analysis in sediments deposited before and after three main volcanic events.  The sources of these events had different distances to lake Chalco: Tláhuac tephra (TTH; 28690 years cal BP), probably produced by the Teuhtli volcano, was a local event; the Tutti Frutti Pumice (PTF; 17000 years cal BP) produced by the Popocatépetl volcano, was an extra-local event and the Upper Toluca Pumice (PTS; 12300 years cal BP) produced by the Nevado de Toluca volcano, was a regional event.  Charcoal accumulation rates (CHAR) and distribution of size particles indicate that paleoclimate was a direct factor defining the intensity and recurrence of fires before and after volcanic activity, as climate defines vegetation type and density, and therefore fuel availability.  Fires before and after the TTH were frequent, local and intense in comparison with fires reconstructed before or after the PTF and PTS events. CHAR values were lower during the more widespread PTF event, than for the local TTH event, although the highest CHAR values were recorded for the most distant, regional, and intense PTS event. These results show that charcoal accumulation rates during the volcanic events in central Mexico cannot be interpreted following traditional model of charcoal particle dispersion. This model have important restrictions in active volcanic regions such as central Mexico.

RATIONALE FOR MONITORING GROUNDWATER LEVELS IN THE REHABILITATED PEATLANDS OF PRIPYAT POLESIE

2020 ◽  
pp. 33-43
Author(s):  
Olga N. Ratnicava ◽  
Irina P. Lisitsyna ◽  
Inna V. Аgeichik
Keyword(s):  
Field Studies ◽  
Natural State ◽  
Groundwater Levels ◽  
Discharge Water ◽  
Peat Deposits ◽  
Disturbed Areas ◽  
Key Points ◽  
Before And After ◽  
Vegetation Maps ◽  
Relationship Of

Based on studies of geomorphology, stratigraphy, hydrology, various maps of Polesie, zones of influence of amelioration canals, vegetation maps, modern satellite images, as well as field studies of peatlands of Pripyat Polesie, two independent drainage systems have been identified, with a network of amelioration canals that intensively discharge water into the rivers Stwiga and Ybort`. Maps of key points were built In GIS-format, on which five sites were laid in the field within the Mezhch and Neresnya peat deposits for further long-term monitoring of GWL parameters. The locations of the sensors installation are based on the relationship of bog phytocenoses with the average annual GWL values and the amplitude of their fluctuations. Analysis of the GWL parameters before and after environmental rehabilitation measures will allow assessing the effectiveness of planned measures in disturbed areas and obtaining new data on areas of peat deposits in their natural state.

scholarly journals Optimal ash particle refractive index model for simulating the brightness temperature spectrum of volcanic ash clouds from satellite infrared sounder measurements

2021 ◽  
Author(s):  
Hiroshi Ishimoto ◽  
Masahiro Hayashi ◽  
Yuzo Mano
Keyword(s):  
Refractive Index ◽  
Brightness Temperature ◽  
Volcanic Ash ◽  
Satellite Measurements ◽  
Temperature Spectrum ◽  
Index Model ◽  
Rock Types ◽  
Volcanic Events ◽  
Atmospheric Sounding ◽  
Using Data

Abstract. Using data from the Infrared Atmospheric Sounding Interferometer (IASI) measurements of volcanic ash clouds and radiative transfer calculations, we identify the optimal refractive index model for simulating the measured brightness temperature spectrum of volcanic ash material. We assume that the optimal refractive index model has the smallest root mean square of the brightness temperature difference between measurements and simulations for channels in the wavenumber range of 750–1400 cm−1 and compare 21 refractive index models for optical properties of ash particles, including recently published models. From the results of numerical simulations for 164 pixels of IASI measurements for ash clouds from 11 volcanoes, we found that the measured brightness temperature spectrum could be well simulated using certain newly established refractive index models. In the cases of Eyjafjallajökull and Grímsvötn ash clouds, the optimal refractive index models determined through numerical simulation correspond to those deduced from the chemical composition of ash samples for the same volcanic eruption events. This finding suggests that infrared sounder measurement of volcanic ash clouds is an effective approach to estimating the optimal refractive index model. However, discrepancies between the estimated refractive index models based on satellite measurements and the associated volcanic rock types were observed for some volcanic events.

scholarly journals Lidar observation and model simulation of a volcanic-ash-induced cirrus cloud during the Eyjafjallajökull eruption

2012 ◽  
Vol 12 (6) ◽  
pp. 15675-15707 ◽  
Author(s):  
C. Rolf ◽  
M. Krämer ◽  
C. Schiller ◽  
M. Hildebrandt ◽  
M. Riese
Keyword(s):  
Volcanic Ash ◽  
Model Simulation ◽  
Cirrus Cloud ◽  
Backward Trajectories ◽  
Microphysical Properties ◽  
Ice Nuclei ◽  
A Value ◽  
Lidar Measurements ◽  
Before And After ◽  
Western Germany

Abstract. Heterogeneous ice formation induced by volcanic ash from the Eyjafjallajökull volcano eruption in April 2010 is investigated based on the combination of a cirrus cloud observed with a backscatter lidar over Jülich (Western Germany) and model simulations along backward trajectories. The microphysical properties of the cirrus cloud could only be represented by the microphysical model under the assumption of an enhanced number of efficient ice nuclei originating from the volcanic eruption. The ice nuclei (IN) concentration determined by lidar measurements directly before and after cirrus cloud occurrence implies a value of around 0.1 cm−3 (in comparison clean IN conditions: 0.01 cm−3). This leads to a cirrus cloud with rather small ice crystals having a mean radius of 12 μm and a modification of the ice particle number (0.08 cm−3 instead of 3 × 10−4 cm−3 under clean IN conditions). The effectiveness of ice nuclei was estimated by the use of the microphysical model and the backward trajectories based on ECMWF data, establishing a freezing threshold of around 105% relative humidity with respect to ice in a temperature range from −45 to −55 °C. Only with these highly efficient ice nuclei was it possible for the cirrus cloud to be formed in a slightly supersaturated environment.

scholarly journals Quartz OSL dating of late quaternary Chinese and Serbian loess: A cross Eurasian comparison of dust mass accumulation rates

2019 ◽  
Vol 502 ◽  
pp. 30-44 ◽  
Author(s):  
Zoran Perić ◽  
Emma Lagerbäck Adolphi ◽  
Thomas Stevens ◽  
Gábor Újvári ◽  
Christian Zeeden ◽  
...  
Keyword(s):  
Late Quaternary ◽  
Osl Dating ◽  
Accumulation Rates ◽  
Dust Mass ◽  
Mass Accumulation Rates ◽  
Mass Accumulation

scholarly journals The Distal and Local Volcanic Ash in the Late Pleistocene Sediments of the Termination I Interval at the Reykjanes Ridge, North Atlantic, Based on the Study of the Core AMK-340

Geosciences ◽  
2019 ◽  
Vol 9 (9) ◽  
pp. 379
Author(s):  
Matul ◽  
Gablina ◽  
Khusid ◽  
Libina ◽  
Mikhailova
Keyword(s):  
North Atlantic ◽  
Volcanic Ash ◽  
Late Quaternary ◽  
Central Zone ◽  
Younger Dryas ◽  
Quaternary Sediments ◽  
Reykjanes Ridge ◽  
Volcanic Material ◽  
The North ◽  
Russian Research

We made the geochemical analysis of the volcanic material from the sediment core AMK-340 (the Russian research vessel “Akademik Mstislav Keldysh” station 340), the central zone of the Reykjanes Ridge. Two ash-bearing sediment units within the interval of the Termination I can be detected. They correlate with the Ash Zone I in the North Atlantic Late Quaternary sediments having an age of 12,170–12,840 years within the Younger Dryas cold chronozone and 13,600–14,540 years within the Bølling–Allerød warm chronozone. The ash of the Younger Dryas unit is presented mostly by the mafic and persilicic material originated from the Icelandic volcanoes. One sediment sample from this unit contained Vedde Ash material. The ash of the Bølling–Allerød unit is presented mostly by the mafic shards which are related to the basalts of the rift zone on the Reykjanes Ridge, having presumably local origin. Possible detection of Vedde Ash could help to specify the timing of the previously reconstructed paleoceanographic changes for the Termination I in the point of the study: significant warming in the area might have occurred as early as 300 years before the end of the conventional Younger Dryas cold chronozone.

Analysis of Elemental Composition of the Eggshell before and after Incubation in the Loggerhead Turtle (Caretta caretta) in Oman

2011 ◽  
Vol 17 (3) ◽  
pp. 452-460 ◽  
Author(s):  
S.N. Al-Bahry ◽  
I.Y. Mahmoud ◽  
K. Melghit ◽  
I. Al-Amri
Keyword(s):  
Elemental Composition ◽  
Amorphous Material ◽  
Loggerhead Turtle ◽  
Middle Layer ◽  
Caretta Caretta ◽  
Exothermic Peak ◽  
Shell Membrane ◽  
Emergence Success ◽  
Significant Difference ◽  
Before And After

AbstractTo date, there are limited studies on loggerhead turtle (Caretta caretta) eggshell ultrastructure and its elemental composition. Eggs were collected from turtle nests immediately after oviposition and post hatching. Three eggshell layers were recognized. The outer calcareous layer consists of loose nodular units of different shapes and sizes with loose attachment between the units, resulting in numerous spaces and openings. Each unit consists of CaCO3crystals in aragonite (99%) and calcite (1%). The middle layer has several strata with numerous openings connecting the calcareous and the inner shell membrane. Crystallites of the middle layer are a mix of amorphous material with aragonite (62%) and calcite (38%). The inner shell membrane has numerous reticular fibers mixed predominantly with halite (NaCl) and small amounts of sylvite. Thermogravimetry analysis of the calcareous showed a low exothermic peak at 425°C, which corresponds to a transitional phase from aragonite to calcite. A high endothermic peak at 814°C corresponds to decomposition of calcite CaCO3to CaO and CO2. Electron diffraction confirmed the presence of NaCl halite crystal. A significant difference was found in the percentage of elements and crystal configurations in the three layers. This study has value in assessing the emergence success in this endangered species.

Episodic Emergence in the Past 3000 Years at the Akkeshi Estuary, Hokkaido, Northern Japan

2001 ◽  
Vol 56 (2) ◽  
pp. 231-241 ◽  
Author(s):  
Yuki Sawai
Keyword(s):  
Volcanic Ash ◽  
Late Quaternary ◽  
Vertical Crustal Movement ◽  
The Past ◽  
Marine Terraces ◽  
The Pacific ◽  
Tectonically Active ◽  
Emergence Event ◽  
Rapid Emergence ◽  
Northern Japan

AbstractAt the Akkeshi estuary, rapid emergence interrupted Holocene submergence at least four times in the past 3000 years. Each emergence event produced an upward change from estuarine mud to freshwater peat. While the estuarine mud abounds in brackish and marine diatoms, freshwater taxa dominate the peat. Emergence events occurred from 1700 to 2300, 1000 to 1300, and 500 to 700 cal yr B.P. An additional emergence event predated by several decades a volcanic ash that erupted in A.D. 1694. At least three of the events produced contacts abrupt enough to represent uplift during earthquakes. Such uplift may reconcile seemingly conflicting records of vertical crustal movement in eastern Hokkaido. This tectonically active area, which is being subducted by the Pacific plate at 8 cm/yr, contains marine terraces that imply 0.1–0.5 mm/yr of net uplift in the late Quaternary. However, these terraces adjoin tide gages that recorded 8–9 mm/yr of steady submergence in the 20th century. The terrace uplift need not conflict with the gaged submergence if the region is subject to occasional coseismic uplift, as during the emergence events implied by Holocene geology near Akkeshi.

Sign in / Sign up

Export Citation Format

Share Document