Late Pleistocene glaciolacustrine MIS 3 record at Fagnano Lake, Central Tierra del Fuego, southern Argentina

2020 ◽  
pp. 1-15
Author(s):  
Romina Sanci ◽  
María J. Orgeira ◽  
Andrea Coronato ◽  
Rita Tófalo ◽  
Héctor O. Panarello ◽  
...  
Keyword(s):  
Organic Matter ◽  
Late Pleistocene ◽  
Tierra Del Fuego ◽  
C3 Plant ◽  
Air Masses ◽  
Ice Cap ◽  
Average Sedimentation Rate ◽  
San Sebastian ◽  
Patagonian Andes ◽  
Calculated Average

Abstract A late Pleistocene glaciolacustrine record was studied at Fagnano Lake (54°35´S, 67°20´W), central Isla Grande de Tierra del Fuego, southernmost South America. Two profiles from the Río Valdéz outcrop were collected for isotopic, geochemical, sedimentological, and geophysical analyses. The sedimentological characteristics, such as rhythmites, presence of dropstones, absence of fossil record, and scarce presence of organic matter, suggest deposition in an ice-contact lake, possibly dammed by the Fagnano paleoglacier. Organic matter of C3 plant origin suggests certain cold and wet conditions. A chronology of the late Pleistocene outcrop was obtained from five 14C ages resulting in an age-depth model. The time span covered 49.01 cal ka BP to 32.14 cal ka BP. Based on the thickness of the deposit and the calculated average sedimentation rate, the glacial environment could have been present in the study area prior to the last glacial maximum, in agreement with the Inútil-San Sebastián paleoglacier. Both glaciers flowed from the same mountain ice sheet in the Darwin Cordillera, which makes it possible to infer a different behavior of this ice cap from those of the Patagonian Andes, perhaps forced by different atmospheric dynamics and proximity to the wet and cold subantarctic air masses.

scholarly journals Revisiting Late Pleistocene glacier dynamics north-west of the Feldberg, southern Black Forest, Germany

2020 ◽  
Vol 69 (1) ◽  
pp. 61-87
Author(s):  
Felix Martin Hofmann ◽  
Florian Rauscher ◽  
William McCreary ◽  
Jan-Paul Bischoff ◽  
Frank Preusser
Keyword(s):  
Late Pleistocene ◽  
Remote Sensing Data ◽  
Black Forest ◽  
Air Masses ◽  
North West ◽  
Ice Cap ◽  
Last Glaciation ◽  
The Alps ◽  
Area North ◽  
Glacial Landforms

Abstract. The southern Black Forest was temporarily covered by a ∼1000 km2 large ice cap during the Late Pleistocene. However, during the last glaciation maximum in the Alps the atmospheric circulation over Europe was presumably characterised by the advection of humid air masses from the Mediterranean Sea. As a consequence, the ice cap of the Black Forest was likely in a leeward position due to its location north of the Alps. This raises the question of whether it reached its last maximum extent simultaneously with the glaciers in the Alps. As modern dating techniques have hitherto not been applied to the southern Black Forest, the timing of the last local glaciation maximum remains poorly constrained. As a first step towards an independent regional glacier chronology, we present a critical re-examination of glacial landforms in the area north-west of the highest summit of the Black Forest (Feldberg, 1493 m a.s.l.). It relies on both the analysis of remote sensing data and field mapping. The review of previous studies highlights important disagreements regarding the location of ice-marginal positions and their correlation. In addition, our findings challenge earlier studies on the glaciation of the Black Forest: some previously described ice-marginal positions could not be confirmed, whereas some of the newly identified moraines are described for the first time. This highlights the need for detailed geomorphological investigations prior to the application of geochronological methods. A multi-ridged series of terminal moraines in one of the studied valleys, Sankt Wilhelmer Tal, is proposed as the main target for future dating. Due to discrepancies with earlier studies, future efforts should reinvestigate other key areas related to the last glaciation of the southern Black Forest.

scholarly journals Dissolved and Particulate Organic Carbon in Icelandic Proglacial Streams: A First Estimate

Water ◽  
2019 ◽  
Vol 11 (4) ◽  
pp. 748 ◽  
Author(s):  
Peter Chifflard ◽  
Christina Fasching ◽  
Martin Reiss ◽  
Lukas Ditzel ◽  
Kyle S. Boodoo
Keyword(s):  
Organic Matter ◽  
Organic Carbon ◽  
Particulate Organic Carbon ◽  
Ice Cap ◽  
Glacier Terminus ◽  
Fluorescence Measurements ◽  
Sampling Locations ◽  
Carbon Release ◽  
Annual Carbon ◽  
Spatio Temporal

Here for the first time, we analyze the concentration of dissolved (DOC) and particulate organic carbon (POC), as well as its optical properties (absorbance and fluorescence) from several proglacial streams across Iceland, the location of Europe’s largest non-polar ice cap. We found high spatial variability of DOC concentrations and dissolved organic matter (DOM) composition during peak melt, sampling 13 proglacial streams draining the 5 main Icelandic glaciers. Although glacial-derived organic matter (OM) was dominated by proteinaceous florescence, organic matter composition was variable among glaciers, often exhibiting relatively higher aromatic content and increased humification (based on absorbance and fluorescence measurements) closer to the glacier terminus, modulated by the presence of glacial lakes. Additional sampling locations the in flow path of the river Hvitá revealed that while POC concentrations decreased downstream, DOC concentrations and the autochthonous fraction of OM increased, suggesting the reworking of the organic carbon by microbial communities, with likely implications for downstream ecosystems as glaciers continue to melt. Based on our measured DOC concentrations ranging from 0.11 mg·L−1 to 0.94 mg·L−1, we estimate a potential annual carbon release of 0.008 ± 0.002 Tg·C·yr−1 from Icelandic glaciers. This non-conservative first estimate serves to highlight the potentially significant contribution of Icelandic pro-glacial streams to the global carbon cycle and the need for the quantification and determination of the spatio-temporal variation of DOC and POC fluxes and their respective drivers, particularly in light of increased rates of melting due to recent trends in climatic warming.

Late Pleistocene Cosmogenic 36Cl Glacial Chronology of the Southwestern Ahklun Mountains, Alaska

2001 ◽  
Vol 56 (2) ◽  
pp. 148-154 ◽  
Author(s):  
Jason P. Briner ◽  
Terry W. Swanson ◽  
Marc Caffee
Keyword(s):  
Late Pleistocene ◽  
Outlet Glacier ◽  
Ice Volume ◽  
Ice Cap ◽  
Global Ice Volume ◽  
Exposure Age ◽  
Alpine Glaciers ◽  
Glacial Chronology ◽  
Glacier Advance ◽  
Exposure Ages

AbstractThirty-two cosmogenic 36Cl surface exposure ages constrain the timing of two late Pleistocene glacial advances in the western Ahklun Mountains, southwestern Alaska. Boulders were sampled from one early Wisconsin (sensu lato) and six late Wisconsin moraines deposited by ice-cap outlet glaciers and local alpine glaciers. Four moraine boulders deposited during an extensive early Wisconsin ice-cap outlet glacier advance have a mean surface exposure age of 60,300±3200 yr. A moraine deposited by an ice-cap outlet glacier during the restricted late Wisconsin advance has a mean surface exposure age of 19,600±1400 yr. Five moraines deposited by late Wisconsin alpine glaciers have mean ages that range between 30,000 and 17,000 yr. The 36Cl ages are consistent with limiting 14C and thermoluminescence ages from related deposits and indicate that Ahklun Mountains glaciers reached their most extensive position of the last glaciation early during the late Pleistocene, in contrast to the deep-sea isotopic record of global ice volume.1

scholarly journals Subantarctic macrotidal flats, cheniers and beaches in San Sebastian Bay, Tierra Del Fuego, Argentina

1999 ◽  
Vol 160 (3-4) ◽  
pp. 301-326 ◽  
Author(s):  
Federico Vilas ◽  
Alfredo Arche ◽  
Marcelo Ferrero ◽  
Federico Isla
Keyword(s):  
Tierra Del Fuego ◽  
San Sebastian

Paleosol (organic matter and pedogenic carbonates) and paleontological δ13C records applied to the paleoecology of late Pleistocene–Holocene in Mexico

2016 ◽  
Vol 418 ◽  
pp. 147-164 ◽  
Author(s):  
T. Cruz-y-Cruz ◽  
V.A. Pérez-Crespo ◽  
K. Pustovoytov ◽  
S. Sedov ◽  
P. Morales-Puente ◽  
...  
Keyword(s):  
Organic Matter ◽  
Late Pleistocene ◽  
Pedogenic Carbonates

Metal contamination of natural surface soils from long-range atmospheric transport: Existing and missing knowledge

2006 ◽  
Vol 14 (3) ◽  
pp. 169-186 ◽  
Author(s):  
Eiliv Steinnes ◽  
Andrew J Friedland
Keyword(s):  
Organic Matter ◽  
Long Range ◽  
Atmospheric Transport ◽  
Long Range Transport ◽  
Surface Soils ◽  
Air Masses ◽  
Range Transport ◽  
Zinc Cadmium ◽  
Lead Zinc ◽  
Temporal And Spatial

This review focuses on the long-range atmospheric transport of metals to organic-rich surface soils (mostly 50–90% organic matter) in the temperate, coniferous, and boreal zones of North America and Europe. From various air-pollution related measurements (air, precipitation, moss, peat cores) Pb and Zn are known to be transported long distances in the air in large amounts. Arsenic, Cd, Hg, Sb, and Se are also typical representatives of long-range transported air masses, and there is evidence that Ag, Bi, In, Mo, Tl, and W belong to this group of elements. Through the use of “environmental archives” such as ice and peat cores it has become evident that long-range transport of pollutants and associated contamination of natural surfaces is not just a recent phenomenon. There is compelling evidence for widespread enrichment of surface soil horizons in Pb from long-range transport, and many studies support enrichment of Zn. Mercury is also generally elevated by anthropogenic emissions over natural levels in organic-rich surface soils, whereas results for Cd are less conclusive. There is evidence that As, Se, Ag, Mo, In, Sb, W, Tl, and Bi all are subject to some enrichment in organic-rich surface soils from long-range atmospheric transport, but studies are still few for most of these elements. With the exception of Pb, little is known about residence times of the elements in the organic-rich surface horizon, and more research is needed on this topic. Further studies are desirable on the temporal and spatial trends in supply of the above elements, which are poorly known in large parts of the northern temperate zone.Key words: natural soils, metals, long-range atmospheric transport, organic matter, lead, zinc, cadmium, mercury.

Late Pleistocene Glaciation of the Southwestern Ahklun Mountains, Alaska

2000 ◽  
Vol 53 (1) ◽  
pp. 13-22 ◽  
Author(s):  
Jason P. Briner ◽  
Darrell S. Kaufman
Keyword(s):  
Late Pleistocene ◽  
Equilibrium Line ◽  
Equilibrium Line Altitude ◽  
Sea Ice Extent ◽  
Ice Volume ◽  
Ice Cap ◽  
Global Ice Volume ◽  
Alpine Glaciers ◽  
Isotopic Signal ◽  
The Bering Sea

AbstractGlacial deposits in the southwestern Ahklun Mountains, southwestern Alaska, record two major glacier advances during the late Pleistocene. The Arolik Lake and Klak Creek glaciations took place during the early and late Wisconsin, respectively. During the Arolik Lake glaciation, outlet glaciers emanated from an ice cap centered over the central portion of the Ahklun Mountains and expanded beyond the present coast. During the Klak Creek glaciation, ice-cap outlet glaciers terminated ∼60 km upvalley from Arolik Lake moraines. The area also supported numerous alpine glaciers that expanded from small massifs. During both episodes of glaciation, these alpine glaciers apparently reached their maximum positions sometime after the retreat of the ice-cap outlet glaciers. Equilibrium-line altitudes for reconstructed alpine glaciers of the Klak Creek glaciation average ∼390 ± 100 m elevation in the western Ahklun Mountains, which is at most 500 m, and possibly only 200 m, below the estimated modern equilibrium-line altitude. The maximum late Pleistocene advance in the southwestern Ahklun Mountains occurred during the early Wisconsin, similar to advances elsewhere in western Alaska, but in contrast to the isotopic signal in the deep-sea record of global ice volume. The restricted extent of Klak Creek glaciers might reflect the increased distance to the Bering Sea resulting from eustatic sea-level regression and decreased evaporation resulting from lower sea-surface temperatures and increased sea-ice extent.

scholarly journals Feeding ecology of the crab Munida subrugosa (Decapoda: Anomura: Galatheidae) in the Beagle Channel, Argentina

2004 ◽  
Vol 84 (2) ◽  
pp. 359-365 ◽  
Author(s):  
M. Carolina Romero ◽  
Gustavo A. Lovrich ◽  
Federico Tapella ◽  
Sven Thatje
Keyword(s):  
Organic Matter ◽  
Feeding Habits ◽  
Stomach Contents ◽  
Superficial Layer ◽  
Tierra Del Fuego ◽  
Crab Species ◽  
Monthly Basis ◽  
Beagle Channel ◽  
Food Items ◽  
Autumn And Winter

Munida subrugosa is the most abundant galatheid crab species in the Beagle Channel (55°S 68°W) off Tierra del Fuego, Argentina. Samples of crabs and the epibenthic community were taken on a monthly basis at two different depth strata (<40 m and >70 m), by means of epibenthic trawling from 1998 to 1999. Stomach contents from 1582 crabs were analysed, out of which only 2% had empty stomachs. The quantity of food in the stomach contents was clearly seasonal and similar at both depths. The organic matter varied throughout the year and between both depths, being significantly higher in summer/spring than in autumn/winter. Munida subrugosa shows two different and simultaneous feeding habits: (1) as a predator M. subrugosa feeds on crustaceans, algae, and polychaetes; and (2) as a deposit feeder M. subrugosa consumes particulate organic matter and organisms associated with the superficial layer of the sediment. The composition of the diet of Munida subrugosa was similar for both years, and independent of depth, sex or season. Munida subrugosa selected crustaceans only in autumn and winter, whereas most food items were found according to their availability in the habitat.

scholarly journals Etnografía histórica de la migración croata y chilota en la fiebre del oro en Porvenir, Tierra del Fuego, Chile 1930-1990

2020 ◽  
Author(s):  
Juan Manuel Saldivar Arellano
Keyword(s):  
Tierra Del Fuego ◽  
San Sebastian

El artículo muestra hallazgos etnográficos sobre la fiebre del oro e incorporación de pirquineros croatas y chilotes en las inmediaciones del cordón Baquedano de Porvenir, Tierra del Fuego, Chile. Fueron dos etapas de fetichismo aurífero desarrolladas entre las décadas de 1883-1909 y 1930-1990. La primera se inició con el descubrimiento del mineral a través de expediciones europeas que encallaron en playas fuego-patagónicas; después los territorios fueron explotados por Julio Popper, quien formó la Compañía Anónima de Lavaderos de Oro del Sud trazando la ruta del oro desde Cabo Vírgenes hasta Punta Arenas, Isla Navarino, cabo de Hornos, Bahía Aguirre, Sloggett, Nueva, Picton y Lennox, siendo el Páramo en San Sebastián, su principal centro de operaciones. La segunda se desarrolló a través de la organización de comunidades de pirquineros croatas y chilotes, quienes continuaron con la explotación de manera artesanal en los yacimientos de la cordillera fueguina. La fiebre del oro contribuyó en la fundación de Porvenir, destacando las inversiones en ramos generales, hotelería y ocio como parte de las economías periféricas, además de la creciente industria lanar que continuó como economía duradera.

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