Antarctic erosion history reconstructed by Terre Adélie moraine geochronology

2020 ◽  
Vol 32 (5) ◽  
pp. 382-395
Author(s):  
Encelyn Voisine ◽  
Yann Rolland ◽  
Matthias Bernet ◽  
Julien Carcaillet ◽  
Guillaume Duclaux ◽  
...  
Keyword(s):  
Little Ice Age ◽  
Fission Track ◽  
Younger Dryas ◽  
East Antarctica ◽  
Ice Age ◽  
Apatite Fission Track ◽  
Glacial Erosion ◽  
Cosmogenic Nuclide ◽  
Erosion History ◽  
Terre Adélie

AbstractWe report apatite fission-track and 10Be terrestrial cosmogenic nuclide (TCN) dating of 14 moraine boulders originating from inland Terre Adélie, East Antarctica. These data show cooling of the Proterozoic Terre Adélie craton at < ~120°C between 350 and 300 Ma, suggesting > 4 km temperate glacial erosion during the Late Palaeozoic Ice Age, followed by nearly null Mesozoic erosion and low glacial erosion (< 2 km) in the Cenozoic. Based on glacial flux maps, the origin of the boulders may be located ~400 km upstream. Preliminary TCN (10Be) datings of moraine boulders cluster within the last 30 ka. Cosmogenic ages from the Lacroix Nunatak suggest a main deglaciation after the Younger Dryas at c. 10 ka, while those of Cap Prud'homme mostly cluster at 0.6 ka, in agreement with an exhumation of boulders during the Little Ice Age.

scholarly journals Tree-ring radiocarbon reveals reduced solar activity during Younger Dryas cooling

2020 ◽  
Author(s):  
Adam Sookdeo ◽  
Bernd Kromer ◽  
Florian Adolphi ◽  
Jürg Beer ◽  
Nicolas Brehm ◽  
...  
Keyword(s):  
Solar Activity ◽  
Tree Ring ◽  
North Atlantic ◽  
Little Ice Age ◽  
Ice Core ◽  
Younger Dryas ◽  
Ice Age ◽  
The North ◽  
Long Duration ◽  
Clear Sign

&lt;p&gt;The Younger Dryas stadial (YD) was a return to glacial-like conditions in the North Atlantic region that interrupted deglacial warming around 12900 cal BP (before 1950 AD). Terrestrial and marine records suggest this event was initiated by the interruption of deep-water formation arising from North American freshwater runoff, but the causes of the millennia-long duration remain unclear. To investigate the solar activity, a possible YD driver, we exploit the cosmic production signals of tree-ring radiocarbon (&lt;sup&gt;14&lt;/sup&gt;C) and ice-core beryllium-10 (&lt;sup&gt;10&lt;/sup&gt;Be). Here we present the highest temporally resolved dataset of &lt;sup&gt;14&lt;/sup&gt;C measurements (n = 1558) derived from European tree rings that have been accurately extended back to 14226 cal BP (&amp;#177;8, 2-&amp;#963;), allowing precise alignment of ice-core records across this period. We identify a substantial increase in &lt;sup&gt;14&lt;/sup&gt;C and &lt;sup&gt;10&lt;/sup&gt;Be production starting at 12780 cal BP is comparable in magnitude to the historic Little Ice Age, being a clear sign of grand solar minima. We hypothesize the timing of the grand solar minima provides a significant amplifying factor leading to the harsh sustained glacial-like conditions seen in the YD.&lt;/p&gt;

Thermal history of the Vestfold Hills (East Antarctica) between Lambert rifting and Gondwana break-up, evidence from apatite fission track data

2007 ◽  
Vol 19 (1) ◽  
pp. 97-106 ◽  
Author(s):  
Frank Lisker ◽  
Christopher J.L. Wilson ◽  
Helen J. Gibson
Keyword(s):  
Large Scale ◽  
Fission Track ◽  
East Antarctica ◽  
Prydz Bay ◽  
Apatite Fission Track ◽  
Subsequent Evolution ◽  
History Of ◽  
Thermal Histories ◽  
Break Up ◽  
Vestfold Hills

Analysis of five basement samples from the Vestfold Hills (East Antarctica) reveals pooled apatite fission track (FT) ages ranging from 188 to 264 Ma and mean lengths of 13.7 to 14.9 μm. Quantitative thermal histories derived from these data give consistent results indicating onset of cooling/denudation began sometime prior to 240 Ma, with final cooling below 105°–125°C occurring between 240 and 220 Ma (Triassic). A Cretaceous denudation phase can be inferred from the sedimentary record of the Prydz Bay offshore the Vestfold Hills. The two denudational episodes are likely associated with Palaeozoic large-scale rifting processes that led to the formation of the adjacent Lambert Graben, and to the Cretaceous Gondwana break-up between Antarctica and India. Subsequent evolution of the East Antarctic passive continental margin likely occurred throughout the Cenozoic based on the depositional record in Prydz Bay and constraints (though tentative) from FT data.

Holocene glacier fluctuations inferred from lacustrine sediment, Emerald Lake, Kenai Peninsula, Alaska

2016 ◽  
Vol 85 (1) ◽  
pp. 34-43 ◽  
Author(s):  
Taylor S. LaBrecque ◽  
Darrell S. Kaufman
Keyword(s):  
Little Ice Age ◽  
Younger Dryas ◽  
Lacustrine Sediment ◽  
Ice Age ◽  
Sedimentary Sequence ◽  
Sharp Transition ◽  
Kenai Peninsula ◽  
The Holocene ◽  
History Of ◽  
Age Model

Physical and biological characteristics of lacustrine sediment from Emerald Lake were used to reconstruct the Holocene glacier history of Grewingk Glacier, southern Alaska. Emerald Lake is an ice-marginal threshold lake, receiving glaciofluvial sediment when Grewingk Glacier overtops the topographic divide that separates it from the lake. Sub-bottom acoustical profiles were used to locate core sites to maximize both the length and resolution of the sedimentary sequence recovered in the 4-m-long cores. The age model for the composite sequence is based on 13 14C ages and a 210Pb profile. A sharp transition from the basal inorganic mud to organic-rich mud at 11.4 ± 0.2 ka marks the initial retreat of Grewingk Glacier below the divide of Emerald Lake. The overlaying organic-rich mud is interrupted by stony mud that records a re-advance between 10.7 ± 0.2 and 9.8 ± 0.2 ka. The glacier did not spill meltwater into the lake again until the Little Ice Age, consistent with previously documented Little Ice Ages advances on the Kenai Peninsula. The retreat of Grewingk Glacier at 11.4 ka took place as temperature increased following the Younger Dryas, and the subsequent re-advance corresponds with a climate reversal beginning around 11 ka across southern Alaska.

scholarly journals Equilibrium-line altitudes and rock glaciers during the Younger Dryas cooling event, Ferwall group, western Tyrol, Austria

1999 ◽  
Vol 28 ◽  
pp. 141-145 ◽  
Author(s):  
Rudolf Sailer ◽  
Hanns Kerschner
Keyword(s):  
Little Ice Age ◽  
Younger Dryas ◽  
Late Glacial ◽  
Ice Age ◽  
Equilibrium Line ◽  
Rock Glacier ◽  
Equilibrium Line Altitude ◽  
Discontinuous Permafrost ◽  
Rock Glaciers ◽  
Temperature Depression

AbstractThree cirques in the Ferwall group, western Tyrol, Austria, which are characterized by distinct Late-glacial moraines and rock glaciers, are discussed. The morphology of the moraines and the depression of the equilibrium-line altitude suggest they were deposited during the Egesen Stadial (Younger Dryas), which can be subdivided into three substages. Rock-glacier formation was initialized during or after the Egesen II substage. They became inactive at the Pleistocene—Holocene transition. ELA values are 290–320 m lower than the Little Ice Age ELA during the Egesen I substage, 190–230 m lower during the Egesen II substage and 120 —160 m lower during the Egesen III substage. The lowering of the rock-glacier belt (discontinuous permafrost) during and after the Egesen II substage is about 400 m, indicating a mean annual air-temperature depression in the order of 3 K. During the Egesen I (earlyYounger Dryas), the climate seems to have been rather cold and wet with precipitation similar to present-day values. During later phases (Egesen II and III), the climate remained cold and became increasingly drier. The rise of the ELA during the Egesen I—III substages seems to have been mainly caused by a decrease in precipitation.

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