Elemental composition of the Laguna Potrok Aike sediment sequence reveals paleoclimatic changes over the past 51 ka in southern Patagonia, Argentina

2014 ◽  
Vol 52 (4) ◽  
pp. 349-366 ◽  
Author(s):  
Annette Hahn ◽  
◽  
Pierre Kliem ◽  
Markus Oehlerich ◽  
Christian Ohlendorf ◽  
...  
Keyword(s):  
Elemental Composition ◽  
The Past ◽  
Paleoclimatic Changes ◽  
Southern Patagonia

scholarly journals Contrasting glacier variations of Glaciar Perito Moreno and Glaciar Ameghino, Southern Patagonia Icefield

2015 ◽  
Vol 56 (70) ◽  
pp. 26-32 ◽  
Author(s):  
Masahiro Minowa ◽  
Shin Sugiyama ◽  
Daiki Sakakibara ◽  
Takanobu Sawagaki
Keyword(s):  
Mass Balance ◽  
Area Ratio ◽  
Elevation Change ◽  
Climate Conditions ◽  
Altitude Profile ◽  
The Past ◽  
Surface Elevation Change ◽  
Southern Patagonia ◽  
Accumulation Area Ratio ◽  
Strong Control

AbstractGlaciar Perito Moreno (GPM) and Glaciar Ameghino (GA), Southern Patagonia Icefield, are in contact in the accumulation area, but have shown contrasting frontal variations in the past few decades. To investigate recent changes of the two glaciers and processes controlling the different responses to similar climate conditions, we measured surface elevation change from 2000 to 2008 and terminus positions from 1999 to 2012 using several types of satellite data. GPM shows no significant changes in terminus position and 0.4 ± 0.3 m a–1 thickening over the period, whereas GA retreated 55 ± 2 m a–1 and thinned 2.6 ± 0.3 m a–1. Mass-balance measurements over the period 1999/2000 show that accumulation at GPM was ten times greater than that at GA, but ablation was only three times greater. The mass-balance–altitude profile is similar for the two glaciers; differences in the mass-balance distribution are caused by differences in the accumulation–area ratio (AAR). Our results suggest that the AAR and the calving flux exert strong control on the evolution of glaciers in the region.

scholarly journals Little ice age advance and retreat of Glaciar Jorge Montt, Chilean Patagonia, recorded in maps, air photographs and dendrochronology

2011 ◽  
Vol 7 (5) ◽  
pp. 3131-3164 ◽  
Author(s):  
A. Rivera ◽  
M. Koppes ◽  
C. Bravo ◽  
J. C. Aravena
Keyword(s):  
Little Ice Age ◽  
Dynamic Responses ◽  
Ice Age ◽  
Past Century ◽  
Present Position ◽  
Tidewater Glaciers ◽  
The Past ◽  
Chilean Patagonia ◽  
Southern Patagonia ◽  
Induced Changes

Abstract. Glaciar Jorge Montt (48°20' S/73°30' W), one of the main tidewater glaciers of the Southern Patagonian Icefield (SPI), has experienced the fastest frontal retreat observed in Patagonia during the past century, with a recession of 19.5 km between 1898 and 2011. This record retreat uncovered trees overridden during the Little Ice Age (LIA) advance of the glacier. Samples of these trees were dated using radiocarbon methods, yielding burial ages between 460 and 250 cal yr BP. The dendrochronology and maps indicate that Glaciar Jorge Montt was at its present position before the beginning of the LIA, in concert with several other glaciers in Southern Patagonia, and reached its maximum advance position between 1650 and 1750 AD. The post-LIA retreat is most likely triggered by climatically induced changes during the 20th century, however, Glaciar Jorge Montt has responded more dramatically than its neighbours. The retreat of Jorge Montt opened a new fjord 19.5 km long, and up to 391 m deep, with a varied bathymetry well correlated with glacier retreat rates, suggesting that dynamic responses of the glacier are at least partially connected to near buoyancy conditions at the ice front, resulting in high calving fluxes, accelerating thinning rates and rapid ice velocities.

Alumina Characterization by XRF

1989 ◽  
Vol 33 ◽  
pp. 685-690 ◽  
Author(s):  
Frank R. Feret
Keyword(s):  
Sample Preparation ◽  
Elemental Composition ◽  
Elemental Analysis ◽  
Light Elements ◽  
The Past ◽  
Preparation Techniques ◽  
Analytical Program

One of the most important properties that characterizes alumina is its elemental composition. Although XRF has been applied to the analysis of aluminas for the past three decades, special aluminas have always presented a maj or challenge. Moreover, only recently did it become possible to analyze for light elements such as Na. Two new sample preparation techniques for elemental analysis of aluminas by XRF were developed. One is based on briquetted powders, another involves fused samples. Their advantages and limitations will be presented. In the case of fusion one analytical program was applied to aII types of aluminas, The performance of each method will be discussed.

Loess depositional dynamics and paleoclimatic changes in the Yili Basin, Central Asia, over the past 250 ka

CATENA ◽  
2020 ◽  
Vol 195 ◽  
pp. 104881
Author(s):  
He Yang ◽  
Guoqiang Li ◽  
Xin Huang ◽  
Xiaoyan Wang ◽  
Yunian Zhang ◽  
...  
Keyword(s):  
Central Asia ◽  
The Past ◽  
Paleoclimatic Changes

Dissimilarity Mapping Between Fossil and Contemporary Pollen Spectra in Europe for the Past 13,000 Years

1990 ◽  
Vol 33 (3) ◽  
pp. 360-376 ◽  
Author(s):  
Brian Huntley
Keyword(s):  
Distance Measure ◽  
Threshold Value ◽  
Late Glacial ◽  
The Holocene ◽  
The Past ◽  
Rates Of Change ◽  
Paleoclimatic Changes ◽  
Chord Distance ◽  
Changing Patterns

AbstractThe degree of analogy between fossil and contemporary pollen spectra in Europe has been investigated using the chord-distance dissimilarity measure. No-analog pollen spectra represent vegetation without a modern analog and hence, by inference, represent macroclimatic conditions different from any occurring in the region today. Such spectra have minimum chord distances that exceed a threshold value assessed using contemporary samples from the same and different vegetation u units. Contoured maps of minimum chord distance portray the changing patterns of analogous and no-analog pollen spectra, and hence vegetation units, since 13,000 yr B.P. No-analog vegetation units have been extensive in some regions for much of the Holocene, persisting as recently as 1000 years ago in many areas. The chord-distance measure has also been used to explore the patterns, extent, and rates of change in European pollen spectra since 13,000 yr B.P. Pollen spectra changed rapidly during late-glacial and early Holocene times and during the last millennium. Paleoclimatic changes have brought about the major changes in the Holocene paleovegetation of Europe. Human impact upon European vegetation has obscured neither the contemporary relationship between pollen spectra and vegetation nor the climatically determined long-term changes of vegetation across the continent since 13,000 yr B.P.

scholarly journals Volcanism and geochemistry of soil and vegetation cover of Kamchatka. Communication 2. Specificity of forming the elemental composition of volcanic soil in cold and humid conditions

2019 ◽  
pp. 25-33
Author(s):  
L. V. Zakharikhina ◽  
Yu. S. Litvinenko
Keyword(s):  
Chemical Composition ◽  
Elemental Composition ◽  
Vegetation Cover ◽  
Chemical Elements ◽  
Volcanic Rocks ◽  
Volcanic Soils ◽  
Volcanic Soil ◽  
Basic Composition ◽  
The Past ◽  
Acid Volcanics

Volcanic soils of Kamchatka have the low contents of most the chemical elements in relation to their overall prevalence in the soils of continents and volcanic soils of Europe. Relatively increased gross contents of elements typical for volcanic rocks of medium and basic composition: Na, Ca, Mg, Cd, Mn, Co, Cu, and steadily low contents of elements characteristic of acid volcanics: La, Ce, Pr, Nd, Nb, Hf, Tl, Rb and Th, is most characteristic of the soils of different areas of the peninsula. The existing in the past and currently observed different conditions of volcanism in the previously allocated soil areas of Kamchatka determine the diversity of the chemical composition of the soils in these territories.

Sign in / Sign up

Export Citation Format

Share Document