scholarly journals Implications of till-provenance studies for glaciological reconstructions of the paleoglaciers of Wildhorse Canyon, Idaho, U.S.A.

1996 ◽  
Vol 22 ◽  
pp. 93-101 ◽  
Author(s):  
Keith A. Brugger
Keyword(s):  
Late Pleistocene ◽  
Equilibrium Line ◽  
Equilibrium Line Altitude ◽  
Flow Paths ◽  
Orographic Effects ◽  
Provenance Studies ◽  
Provenance Data ◽  
Mineral Assemblages

Detailed till-provenance studies of moraine complexes in the Wildhorse Canyon area, Idaho, U.S.A., allow inferences to be made regarding the flow paths and dynamics of Wildhorse and Fall Creek Glaciers, the two principal tributaries constituting a late-Pleistocene compound glacier. In particular, the distribution of statistically defined pebble and mineral assemblages within moraine complexes suggests that Wildhorse Glacier contributed a substantially greater volume of ice to the trunk glacier than did Fall Creek Glacier.An initial group of glaciological reconstructions yields estimates for the equilibrium-line altitude (ELA) of the compound glacier that are consistent with those independently arrived at using other methods of ELA determination. Ice-flux calculations imply, however, that for each reconstruction the relative contributions of ice from Wildhorse and Fall Creek Glaciers were about equal, which is inconsistent with the inferences drawn from the till-provenance data. An alternative reconstruction incorporated possible orographic effects on accumulation and ablation by using different ELAs for the two tributary glaciers. Calculations for this reconstruction suggest that the ice flux of Wildhorse Glacier was about twice that of Fall Creek Glacier. This reconstruction is more consistent with the till-provenance data, and furthermore suggests that such data might be invaluable in choosing between seemingly equally viable glaciological reconstructions of paleoglaciers.

scholarly journals Implications of till-provenance studies for glaciological reconstructions of the paleoglaciers of Wildhorse Canyon, Idaho, U.S.A.

1996 ◽  
Vol 22 ◽  
pp. 93-101 ◽  
Author(s):  
Keith A. Brugger
Keyword(s):  
Late Pleistocene ◽  
Equilibrium Line ◽  
Equilibrium Line Altitude ◽  
Flow Paths ◽  
Orographic Effects ◽  
Provenance Studies ◽  
Provenance Data ◽  
Mineral Assemblages

Detailed till-provenance studies of moraine complexes in the Wildhorse Canyon area, Idaho, U.S.A., allow inferences to be made regarding the flow paths and dynamics of Wildhorse and Fall Creek Glaciers, the two principal tributaries constituting a late-Pleistocene compound glacier. In particular, the distribution of statistically defined pebble and mineral assemblages within moraine complexes suggests that Wildhorse Glacier contributed a substantially greater volume of ice to the trunk glacier than did Fall Creek Glacier.An initial group of glaciological reconstructions yields estimates for the equilibrium-line altitude (ELA) of the compound glacier that are consistent with those independently arrived at using other methods of ELA determination. Ice-flux calculations imply, however, that for each reconstruction the relative contributions of ice from Wildhorse and Fall Creek Glaciers were about equal, which is inconsistent with the inferences drawn from the till-provenance data. An alternative reconstruction incorporated possible orographic effects on accumulation and ablation by using different ELAs for the two tributary glaciers. Calculations for this reconstruction suggest that the ice flux of Wildhorse Glacier was about twice that of Fall Creek Glacier. This reconstruction is more consistent with the till-provenance data, and furthermore suggests that such data might be invaluable in choosing between seemingly equally viable glaciological reconstructions of paleoglaciers.

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.

Late Pleistocene glaciers in Darhad Basin, northern Mongolia

2008 ◽  
Vol 69 (2) ◽  
pp. 169-187 ◽  
Author(s):  
Alan R. Gillespie ◽  
Raymond M. Burke ◽  
Goro Komatsu ◽  
Amgalan Bayasgalan
Keyword(s):  
Central Asia ◽  
Lake Sediments ◽  
Late Pleistocene ◽  
Cosmic Ray ◽  
Luminescence Dating ◽  
Equilibrium Line ◽  
Equilibrium Line Altitude ◽  
Exposure Dating ◽  
Northern Mongolia ◽  
Dammed Lake

Late Pleistocene glaciers around Darhad Basin advanced to near their maximum positions at least three times, twice during the Zyrianka glaciation (at ∼ 17–19 ka and ∼ 35–53 ka), and at least once earlier. The Zyrianka glaciers were smaller than their predecessors, but the equilibrium-line altitude (ELA) difference was < 75 m. End moraines of the Zyrianka glaciers were ∼ 1600 m asl; ELAs were 2100–2400 m asl.14C and luminescence dating of lake sediments confirm the existence of paleolake highstands in Darhad Basin before ∼ 35 ka. Geologic evidence and10Be cosmic-ray exposure dating of drift suggests that at ∼ 17–19 ka the basin was filled at least briefly by a glacier-dammed lake ∼ 140 m deep. However, lake sediments from that time have not yet been recognized in the region. A shallower paleolake briefly occupied the basin at ∼ 11 ka, but between ∼ 11 and 17 ka and after ∼ 10 ka the basin was probably largely dry. The timing of maximum glacier advances in Darhad appears to be approximately synchronous across northern Mongolia, but different from Siberia and western Central Asia, supporting the inference that paleoclimate in Central Asia differed among regions.

scholarly journals Late Pleistocene glaciation history of the southern Black Forest, Germany: 10 Be cosmic‐ray exposure dating and equilibrium line altitude reconstructions in Sankt Wilhelmer Tal

2022 ◽  
Author(s):  
Felix Martin Hofmann ◽  
Frank Preusser ◽  
Irene Schimmelpfennig ◽  
Laëtitia Léanni ◽  
Aster team (Georges Aumaître, Karim Keddadouche & Fawzi Zaid
Keyword(s):  
Late Pleistocene ◽  
Cosmic Ray ◽  
Equilibrium Line ◽  
Pleistocene Glaciation ◽  
Black Forest ◽  
Equilibrium Line Altitude ◽  
Exposure Dating ◽  
History Of

scholarly journals Glacier equilibrium line altitude variations during the “Little Ice Age” in the Mediterranean Andes (30◦–37◦ S)

2019 ◽  
Author(s):  
Álvaro González-Reyes ◽  
Claudio Bravo ◽  
Mathias Vuille ◽  
Martin Jacques-Coper ◽  
Maisa Rojas ◽  
...  
Keyword(s):  
Little Ice Age ◽  
Pearson Correlation ◽  
Temporal Changes ◽  
Global Climate Models ◽  
Ice Age ◽  
Equilibrium Line ◽  
Equilibrium Line Altitude ◽  
Mountainous Regions ◽  
The Mean ◽  
The Mediterranean

Abstract. The "Little Ice Age" (LIA; 1500–1850 Common Era (CE)), has long been recognized as the last period when mountain glaciers in many regions of the Northern Hemisphere (NH) recorded extensive growth intervals in terms of their ice mass and frontal position. The knowledge about this relevant paleoclimatic interval is vast in mountainous regions such as the Alps and Rocky Mountains in North America. However, in extra-tropical Andean sub-regions such as the Mediterranean Andes of Chile and Argentina (MA; 30º–37º S), the LIA has been poorly documented. Paradoxically, the few climate reconstructions performed in the MA based on lake sediments and tree rings do not show clear evidence of a LIA climate anomaly as observed in the NH. In addition, recent studies have demonstrated temporal differences between mean air temperature variations across the last millennium between both hemispheres. This motivates our hypothesis that the LIA period was not associated with a significant climate perturbation in the MA region. Considering this background, we performed an experiment using daily climatic variables from three Global Climate Models (GCMs) to force a novel glaciological model. In this way, we simulated temporal variations of the glacier equilibrium-line altitude (ELA) to evaluate the glacier response during the period 1500–1848 CE. Overall, each GCM shows temporal changes in annual ELA, with anomalously low elevations during 1640–1670 and 1800–1848 CE. An interval with high ELA values was identified during 1550–1575 CE. The spectral properties of the mean annual ELA in each GCM present significant periodicities between 2–7 years, and also significant decadal to multi-decadal signals. In addition, significant and coherent cycles at interannual to multi-decadal scales were detected between modeled mean annual ELAs and the first EOF1 extracted from Sea Surface Temperature (SST) within the El Niño 3.4 of each GCM. Finally, significant Pearson correlation coefficients were obtained between the mean annual ELA and Pacific SST on interannual to multi-decadal timescales. According to our findings, we propose that Pacific SST variability was the main modulator of temporal changes of the ELA in the MA region of South America during 1500–1848 CE.

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