Cosmogenic 10Be exposure dating of Bull Lake and Pinedale moraine sequences in the upper Arkansas River valley, Colorado Rocky Mountains, USA

2020 ◽  
Vol 97 ◽  
pp. 125-139 ◽  
Author(s):  
Avriel D. Schweinsberg ◽  
Jason P. Briner ◽  
Joseph M. Licciardi ◽  
Ralph R. Shroba ◽  
Eric M. Leonard
Keyword(s):  
Rocky Mountains ◽  
Last Deglaciation ◽  
Valley Bottom ◽  
Arkansas River ◽  
Climate Conditions ◽  
Exposure Dating ◽  
Colorado Rocky Mountains ◽  
Sawatch Range ◽  
Cosmogenic 10Be ◽  
Exposure Ages

AbstractMany formerly glaciated valleys in the western United States preserve detailed glacial features that span the penultimate glaciation through the last deglaciation; however, numerical age control is limited in many of these systems. We report 35 new cosmogenic 10Be surface exposure ages of moraine boulders in the Sawatch Range, Colorado. Eight ages suggest Bull Lake moraines in Lake Creek (range: 132–120 ka, n = 4) and Clear Creek (range: 187–133 ka, n = 4) valleys may correlate with Marine Isotope Stage 6. In Lake Creek valley, 22 10Be ages from Pinedale end moraines average 20.6 ± 0.6 ka, and 5 10Be ages from a recessional moraine average 15.6 ± 0.7 ka, indicating that glaciers occupied two extended positions at ~21–20 and ~16 ka. The glacial extent dated to ~16 ka was nearly as great as that of the earlier glacial phase, suggesting that climate conditions in the Colorado Rocky Mountains at this time were similar to those of the last glacial maximum. Combining these moraine ages with seven previously published 10Be ages from cirque and valley-bottom bedrock reveals that the Lake Creek paleoglacier lost 82% of its full glacial length in ~1.5 ka and was completely deglaciated by ~14 ka.

scholarly journals Deglaciation of the Colorado Rocky Mountains following the Last Glacial Maximum

2017 ◽  
Vol 43 (2) ◽  
pp. 497 ◽  
Author(s):  
E.M. Leonard ◽  
B.J.B. Laabs ◽  
A.D. Schweinsberg ◽  
C.M. Russell ◽  
J.P. Briner ◽  
...  
Keyword(s):  
Last Glacial Maximum ◽  
Rocky Mountains ◽  
Glacial Maximum ◽  
San Juan ◽  
The South ◽  
Last Glacial ◽  
San Juan Mountains ◽  
The North ◽  
Colorado Rocky Mountains ◽  
Exposure Ages

The availability of almost 180 cosmogenic-radionuclide (CRN) surface-exposure ages from moraine boulders and glacially polished bedrock surfaces makes possible an assessment of the timing and character of the local Last Glacial Maximum (LLGM) and subsequent deglaciation in the Colorado Rocky Mountains. A review of glacial chronologies and numerical modeling results indicates that although glaciers across Colorado responded broadly synchronously, apparent differences in the timing and magnitude of glacier retreat following the LLGM suggest that spatially variable regional forcing, possibly precipitation related, played a role in glacier behavior along with more spatially uniform hemispheric or global forcing. Glaciers in the five ranges examined reached their greatest LLGM extents before ~19.5 ka and abandoned their outermost LLGM moraines between ~23.5 and 19.5 ka. Detailed deglaciation chronologies are available for glaciers in four of the ranges. In the Sawatch Range and Sangre de Cristo Mountains, glaciers were near their LLGM extents at 17-16 ka, before retreating rapidly. In the San Juan Mountains and the Front Range, glaciers may have begun their post-LLGM recession earlier, although early deglaciation is indicated by only a few ages on polished bedrock that potentially contains pre-LLGM CRN inheritance, and thus may be too old. Regardless of the timing of the onset of deglaciation, the equilibrium-line rise associated with deglaciation was earlier and significantly larger in the San Juan Mountains than elsewhere in Colorado. This suggests that the San Juan Mountains, located well to the southwest of the other ranges, may have experienced enhanced precipitation during the LLGM, as did areas farther to the south and west, while LLGM conditions may have been drier in the northern and eastern Colorado ranges. A breakdown in this pattern after the LLGM, with precipitation decreasing in the south and west and increasing in the north and east, may have led to the range-to-range differences evident across Colorado. Deglaciation was nearly complete in all four ranges by 15-13 ka. While some proxy records indicate a later Younger Dryas-age cooling in the Colorado mountains, there is not clear moraine evidence of glacier readvance at that time.

Cosmogenic 10Be exposure dating of glacial erratics on Horseshoe Island in western Antarctic Peninsula confirms rapid deglaciation in the Early Holocene

2019 ◽  
Vol 31 (6) ◽  
pp. 319-331 ◽  
Author(s):  
Attila Çiner ◽  
Cengiz Yildirim ◽  
M. Akif Sarikaya ◽  
Yeong Bae Seong ◽  
Byung Yong Yu
Keyword(s):  
Antarctic Peninsula ◽  
Late Quaternary ◽  
Western Antarctic Peninsula ◽  
Sea Levels ◽  
Exposure Dating ◽  
Ice Stream ◽  
Marguerite Bay ◽  
History Of ◽  
Cosmogenic 10Be ◽  
Exposure Ages

AbstractThe rapid warming observed in the western Antarctic Peninsula gives rise to a fast disintegration of ice shelves and thinning and retreat of marine-terminating continental glaciers, which is likely to raise global sea levels in the near future. In order to understand the contemporary changes in context and to provide constraints for hindcasting models, it is important to understand the Late Quaternary history of the region. Here, we build on previous work on the deglacial history of the western Antarctic Peninsula and we present four new cosmogenic 10Be exposure ages from Horseshoe Island in Marguerite Bay, which has been suggested as a former location of very fast ice stream retreat. Four samples collected from erratic pink granite boulders at an altitude of ~80 m above sea level yielded ages that range between 12.9 ± 1.1 ka and 9.4 ± 0.8 ka. As in other studies on Antarctic erratics, we have chosen to report the youngest erratic age (9.4 ± 0.8 ka) as the true age of deglaciation, which confirms a rapid thinning of the Marguerite Trough Ice Stream at the onset of Holocene. This result is consistent with other cosmogenic age data and other proxies (marine and lacustrine 14C and optically stimulated luminescence) reported from nearby areas.

36Cl exposure dating of post-glacial features along the Mt Vettore Fault (Central Apennines, Italy) constraining fault slip rate and last glacial advance.

2021 ◽  
Author(s):  
Lea Pousse-Beltran ◽  
Lucilla Benedetti ◽  
Jules Fleury ◽  
Paolo Boncio ◽  
Valery Guillou ◽  
...  
Keyword(s):  
Slip Rate ◽  
Fault Slip ◽  
Fault System ◽  
Central Apennines ◽  
Climate Conditions ◽  
Last Glacial ◽  
Exposure Dating ◽  
Fault Systems ◽  
Fault Slip Rate ◽  
Exposure Ages

<p>In the Central Apennines (Italy), up to now, no absolute dating directly based on the moraines has been carried out to constrain glacial oscillation. However, climatic constrains are often used in the Central Apennine to estimate long term (> 10 ka) fault slip rate. In addition slip rate assessments based on offset morphotectonic markers on the main branches of fault systems and encompassing several seismic cycles (> 10 ka) are sparse. This is particularly true for the Monte Vettore-Monte Bove fault system which triggered the 2016-2017 seismic sequence. We thus provide new assessment for the vertical slip rates along the Mt Vettore-Mt Bove fault system.  Offset measurements were made using a 5-cm resolution DEM obtained through a drone survey and constrain a fault scarp height of 15.5 ± 1.4 m and a cumulative offset of 32-40.5 m. Samples were collected from the Valle Lunga terminal moraine at 1710 m asl and yield <sup>36</sup>Cl exposure ages of 12.7 + 2.2/-1.9 ka while the flat, abraded surface located on top of the tectonic scarp yield <sup>36</sup>Cl exposure ages of 23.4 + 5.3/-4.3 ka. Assuming the offset started to accumulate when climate conditions allow its preservation, thus once the surface was abandoned, we constrain a vertical slip rate of 1.2 ± 0.2 mm/yr along the master branch of the Mt Vettore normal fault.  This rate is higher than the ones previously obtained from trenches along secondary splays of the Mt Vettore-Mt Bove and on the Norcia fault systems. Besides, the yielded chronology for the last glacial maximum in that area at ~23 ka is in good agreement with the timing previously proposed for the LGM in the Apennines.</p>

Late Quaternary glaciation of the Tianshan, Central Asia, using cosmogenic 10Be surface exposure dating

2009 ◽  
Vol 72 (2) ◽  
pp. 229-233 ◽  
Author(s):  
Ping Kong ◽  
David Fink ◽  
Chunguang Na ◽  
Feixin Huang
Keyword(s):  
Electron Spin Resonance ◽  
Central Asia ◽  
Late Quaternary ◽  
Glacial Retreat ◽  
Surface Exposure Dating ◽  
Exposure Dating ◽  
Quaternary Glaciation ◽  
Spin Resonance ◽  
Cosmogenic 10Be ◽  
Exposure Ages

AbstractGlacial deposits are present at the head of the Ürümqi River valley, Tianshan, Central Asia. 10Be surface exposure ages of 15 boulders from three sites along a 12 km valley transect range from 9 to 21 ka suggesting emplacement by glacial retreat and advance commencing at the global last glacial maximum (LGM) and most likely abating in the early Holocene. Although the age spread for a given locality is not small, perhaps indicating post-depositional reworking, maximum ages per site are either coeval with or are post-LGM and inconsistent with previous pre-LGM electron spin resonance ages.

scholarly journals 10Be ages of flood deposits west of Lake Nipigon, Ontario: evidence for eastward meltwater drainage during the early Holocene Epoch

2016 ◽  
Vol 53 (3) ◽  
pp. 321-330 ◽  
Author(s):  
Meredith A. Kelly ◽  
Timothy G. Fisher ◽  
Thomas V. Lowell ◽  
Peter J. Barnett ◽  
Roseanne Schwartz
Keyword(s):  
Water Flow ◽  
Coarse Grained ◽  
Laurentide Ice Sheet ◽  
Last Deglaciation ◽  
Climate Conditions ◽  
Exposure Dating ◽  
Large Maximum ◽  
Flood Deposits ◽  
Climate Events ◽  
River Site

The Nipigon channels, located to the west and northwest of Lake Nipigon, Ontario, are thought to have enabled the eastward drainage of meltwater from glacial Lake Agassiz during the last deglaciation. Here we present the first direct ages of flood deposits in two of these channels using 10Be surface exposure dating. Five 10Be ages of a coarse-grained deposit near the Roaring River in the Kaiashk channel complex indicate deglaciation and cessation of water flow by ∼11 070 ± 430 years. To test for inherited nuclides in boulder samples, we also measured the 10Be concentrations of the undersides of two boulders at the Roaring River site. Five 10Be ages of boulders atop a large bedform near Mundell Lake in the Pillar channel complex indicate deglaciation and cessation of water flow by ∼10 770 ± 240 years. Two 10Be ages of nearby bedrock are slightly younger (10 340 ± 260 and 9860 ± 270 years). The 10Be ages from the two sites are statistically indistinguishable and indicate that Laurentide Ice Sheet recession occurred rapidly in the region. We used clast diameters and channel dimensions at the Mundell Lake site to estimate paleodischarge and evaluate the possibility that meltwater drainage influenced climate conditions. We estimate a large maximum discharge of 119 000–159 000 m3·s−1 at the site. However, the timing of meltwater discharge at both Roaring River and Mundell Lake is not contemporaneous with abrupt climate events.

Lake-specific responses to elevated atmospheric nitrogen deposition in the Colorado Rocky Mountains, U.S.A.

Hydrobiologia ◽  
2003 ◽  
Vol 510 (1-3) ◽  
pp. 103-114 ◽  
Author(s):  
Koren R. Nydick ◽  
Brenda Moraska Lafrancois ◽  
Jill S. Baron ◽  
Brett M. Johnson
Keyword(s):  
Nitrogen Deposition ◽  
Rocky Mountains ◽  
Atmospheric Nitrogen Deposition ◽  
Atmospheric Nitrogen ◽  
Colorado Rocky Mountains

scholarly journals Sedimentological characteristics of ice-wedge polygon terrain in Adventdalen (Svalbard) – environmental and climatic implications for the late Holocene

Solid Earth ◽  
2014 ◽  
Vol 5 (2) ◽  
pp. 901-914 ◽  
Author(s):  
M. Oliva ◽  
G. Vieira ◽  
P. Pina ◽  
P. Pereira ◽  
M. Neves ◽  
...  
Keyword(s):  
Organic Matter Content ◽  
Soil Formation ◽  
Matter Content ◽  
Valley Bottom ◽  
Radiocarbon Dates ◽  
Climate Conditions ◽  
Fluvial Terraces ◽  
Ice Wedge ◽  
Homogeneous Composition ◽  
Climatic Severity

Abstract. Ice wedges are widespread periglacial features in the landscape of Adventdalen, Svalbard. The networks of ice wedges have created areas with well-developed polygonal terrains in the lowest fluvial terraces in this valley. We have examined the sedimentological characteristics of the northern and southern banks of the Advent river for palaeoenvironmental purposes. The base of two sedimentary sections reported radiocarbon dates of 3.3 and 3.9 ka BP, respectively. The northern site is constituted by three very different lithostratigraphical units, which suggests that their formation should be related to different environmental and climate conditions. By contrast, the southern section shows a rather homogeneous composition, with no significant variations in grain size and organic matter content. In both cases the uppermost sediments are constituted by a thick aeolian deposit. According to our data, warmer climate conditions may have prevailed during the mid Holocene until 3.3 ka BP with widespread peat formation in the valley bottom. Subsequently, a period with alternating soil formation and aeolian sedimentation took place from 3 to 2.5 ka BP, probably due to increasing climatic severity. During the last millennium a long-term cooling trend has favoured aeolian deposition in the lowest part of Adventdalen.

scholarly journals Late Pleistocene glacial chronologies and paleoclimate in the northern Rocky Mountains

2021 ◽  
Author(s):  
Brendon Quirk ◽  
Elizabeth Huss ◽  
Benjamin Laabs ◽  
Eric Leonard ◽  
Joseph Licciardi ◽  
...  
Keyword(s):  
Rocky Mountains ◽  
Ice Sheet ◽  
Northern Rocky Mountains ◽  
Mountain Ranges ◽  
Mountain Glaciers ◽  
Continental Divide ◽  
Ice Retreat ◽  
Geologic Record ◽  
Glacier Modeling ◽  
Exposure Ages

Abstract. The geologic record of mountain glaciations is a robust indicator of terrestrial paleoclimate change. During the last glaciation, mountain ranges across the western U.S. hosted glaciers while the Cordilleran and Laurentide ice sheets flowed to the west and east of the continental divide, respectively. Records detailing the chronologies and paleoclimate significance of these ice advances have been developed for many sites across North America. However, relatively few glacial records have been developed for mountain glaciers in the northern Rocky Mountains near ice sheet margins. Here, we report cosmogenic beryllium-10 surface exposure ages and numerical glacier modeling results showing that mountain glaciers in the northern Rockies abandoned terminal moraines after the end of the Last Glacial Maximum around 17–18 ka and could have been sustained by −10 to −8.5 °C temperature depressions relative to modern assuming similar or drier than modern precipitation. Additionally, we present a deglacial chronology from the northern Rocky Mountains that indicates while there is considerable variability in initial moraine abandonment ages across the Rocky Mountains, the pace of subsequent ice retreat through the Lateglacial exhibits some regional coherence. Our results provide insight on potential regional mechanisms driving the initiation of and sustained deglaciation in the western U.S. including rising atmospheric CO2 and ice sheet collapse.

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