Chapter 5.5 Gaussberg: volcanology and petrology

2021 ◽  
pp. M55-2018-85
Author(s):  
J. L. Smellie ◽  
K. D. Collerson
Keyword(s):  
Transition Zone ◽  
Pillow Lava ◽  
East Antarctica ◽  
Volcanic Centre ◽  
Kerguelen Plume ◽  
Ice Surface ◽  
Marine Isotope Stage 3 ◽  
Magmatic Event ◽  
The Last Glacial

AbstractGaussberg is a nunatak composed of lamproite pillow lava situated on the coast of East Antarctica. It is the most isolated Quaternary volcanic centre in Antarctica but it is important palaeoenvironmentally and petrologically out of all proportion to its small size. The edifice has a likely low, shield-like, morphology c. 1200 m high and possibly up to 10 km wide, which is unusually large for a lamproite construct. Gaussberg was erupted subglacially at 56 ± 5 ka, which places it late in the last glacial, close to the peak of marine isotope stage 3. The coeval ice sheet was c. 1300 m thick, and c. 420 m has been removed from the ice surface since Gaussberg erupted. Lamproite is a rare ultrapotassic mantle-derived magma, and Gaussberg is one of two type examples worldwide. Although traditionally considered as related in some way to the Kerguelen plume, it is more likely that the Gaussberg magma is a product of a separate magmatic event. It is ascribed to the storage and long-term (Gy) isolation of sediment emplaced by subduction in the Transition Zone of the deep mantle, followed by entrainment and subsequent melting in a plume.

scholarly journals Unglaciated areas in East Antarctica during the Last Glacial (Marine Isotope Stage 3) – New evidence from Rauer Group

2016 ◽  
Vol 153 ◽  
pp. 1-10 ◽  
Author(s):  
Sonja Berg ◽  
Duanne A. White ◽  
Ole Bennike ◽  
Réka-H. Fülöp ◽  
David Fink ◽  
...  
Keyword(s):  
East Antarctica ◽  
Marine Isotope Stage ◽  
Last Glacial ◽  
Marine Isotope Stage 3 ◽  
New Evidence ◽  
The Last Glacial

Satellite Altimeter Results Over East Antarctica

1982 ◽  
Vol 3 ◽  
pp. 32-35 ◽  
Author(s):  
R. L. Brooks
Keyword(s):  
Tracking System ◽  
Ice Sheet ◽  
East Antarctica ◽  
Satellite Altimeter ◽  
Ice Shelves ◽  
Ice Surface ◽  
Operational Lifetime ◽  
Waveform Retracking ◽  
Better Than

During the operational lifetime of the Seasat altimeter from 3 July to 10 October 1978, more than 450 overflights were made over East Antarctica inland to latitude 72°S. An analysis of selected passes over a variety of ice features demonstrates that the oceanographic altimeter performed surprisingly well over the ice sheet and ice shelves, acquiring useful measurements during approximately 70% of each pass. The altimeter's onboard tracking system dampened out the ice-surface elevations, but post-flight retracking of the stored return waveforms reveals excellent ice-surface details. After waveform retracking, the altimeter repeatability is better than ±1 m.

Spatial variation of East Asian winter monsoon evolution between northern and southern China since the last glacial maximum

2021 ◽  
pp. 1-14
Author(s):  
Qin Li ◽  
Haibin Wu ◽  
Jun Cheng ◽  
Shuya Zhu ◽  
Chunxia Zhang ◽  
...  
Keyword(s):  
East Asian Winter Monsoon ◽  
Southern China ◽  
Ice Sheets ◽  
Northern China ◽  
Winter Monsoon ◽  
Asian Winter Monsoon ◽  
Spatial Differences ◽  
The Last Glacial Maximum ◽  
The Last Glacial

Abstract The East Asian winter monsoon (EAWM) is one of the most dynamic components of the global climate system. Although poorly understood, knowledge of long-term spatial differences in EAWM variability during the glacial–interglacial cycles is important for understanding the dynamic processes of the EAWM. We reconstructed the spatiotemporal characteristics of the EAWM since the last glacial maximum (LGM) using a comparison of proxy records and long-term transient simulations. A loess grain-size record from northern China (a sensitive EAWM proxy) and the sea surface temperature gradient of an EAWM index in sediments of the southern South China Sea were compared. The data–model comparison indicates pronounced spatial differences in EAWM evolution, with a weakened EAWM since the LGM in northern China but a strengthened EAWM from the LGM to the early Holocene, followed by a weakening trend, in southern China. The model results suggest that variations in the EAWM in northern China were driven mainly by changes in atmospheric carbon dioxide (CO2) concentration and Northern Hemisphere ice sheets, whereas orbital insolation and ice sheets were important drivers in southern China. We propose that the relative importance of insolation, ice sheets, and atmospheric CO2 for EAWM evolution varied spatially within East Asia.

scholarly journals Mass balance of the Antarctic ice sheet 1992–2016: reconciling results from GRACE gravimetry with ICESat, ERS1/2 and Envisat altimetry

2021 ◽  
pp. 1-27
Author(s):  
H. Jay Zwally ◽  
John W. Robbins ◽  
Scott B. Luthcke ◽  
Bryant D. Loomis ◽  
Frédérique Rémy
Keyword(s):  
Mass Balance ◽  
Antarctic Peninsula ◽  
East Antarctica ◽  
Mantle Material ◽  
West Antarctica ◽  
Mantle Viscosity ◽  
Grounding Line ◽  
The Antarctic ◽  
Total Gain

Abstract GRACE and ICESat Antarctic mass-balance differences are resolved utilizing their dependencies on corrections for changes in mass and volume of the same underlying mantle material forced by ice-loading changes. Modeled gravimetry corrections are 5.22 times altimetry corrections over East Antarctica (EA) and 4.51 times over West Antarctica (WA), with inferred mantle densities 4.75 and 4.11 g cm−3. Derived sensitivities (Sg, Sa) to bedrock motion enable calculation of motion (δB0) needed to equalize GRACE and ICESat mass changes during 2003–08. For EA, δB0 is −2.2 mm a−1 subsidence with mass matching at 150 Gt a−1, inland WA is −3.5 mm a−1 at 66 Gt a−1, and coastal WA is only −0.35 mm a−1 at −95 Gt a−1. WA subsidence is attributed to low mantle viscosity with faster responses to post-LGM deglaciation and to ice growth during Holocene grounding-line readvance. EA subsidence is attributed to Holocene dynamic thickening. With Antarctic Peninsula loss of −26 Gt a−1, the Antarctic total gain is 95 ± 25 Gt a−1 during 2003–08, compared to 144 ± 61 Gt a−1 from ERS1/2 during 1992–2001. Beginning in 2009, large increases in coastal WA dynamic losses overcame long-term EA and inland WA gains bringing Antarctica close to balance at −12 ± 64 Gt a−1 by 2012–16.

scholarly journals Long-Term Effects of Vegetation Treatments in the Chaparral Transition Zone

Rangelands ◽  
2001 ◽  
Vol 23 (1) ◽  
Author(s):  
Kelly N. Fuhrmann ◽  
Timothy E. Crews ◽  
Keyword(s):  
Transition Zone ◽  
Long Term Effects

scholarly journals Are longitudinal ice-surface structures on the Antarctic Ice Sheet indicators of long-term ice-flow configuration?

2014 ◽  
Vol 2 (2) ◽  
pp. 911-933 ◽  
Author(s):  
N. F. Glasser ◽  
S. J. A. Jennings ◽  
M. J. Hambrey ◽  
B. Hubbard
Keyword(s):  
Flow Line ◽  
Ice Sheet ◽  
Surface Structures ◽  
Surface Velocity ◽  
Ice Flow ◽  
Antarctic Ice Sheet ◽  
Ice Surface ◽  
Ice Stream ◽  
The Antarctic

Abstract. Continent-wide mapping of longitudinal ice-surface structures on the Antarctic Ice Sheet reveals that they originate in the interior of the ice sheet and are arranged in arborescent networks fed by multiple tributaries. Longitudinal ice-surface structures can be traced continuously down-ice for distances of up to 1200 km. They are co-located with fast-flowing glaciers and ice streams that are dominated by basal sliding rates above tens of m yr-1 and are strongly guided by subglacial topography. Longitudinal ice-surface structures dominate regions of converging flow, where ice flow is subject to non-coaxial strain and simple shear. Associating these structures with the AIS' surface velocity field reveals (i) ice residence times of ~ 2500 to 18 500 years, and (ii) undeformed flow-line sets for all major flow units analysed except the Kamb Ice Stream and the Institute and Möller Ice Stream areas. Although it is unclear how long it takes for these features to form and decay, we infer that the major ice-flow and ice-velocity configuration of the ice sheet may have remained largely unchanged for several thousand years, and possibly even since the end of the last glacial cycle. This conclusion has implications for our understanding of the long-term landscape evolution of Antarctica, including large-scale patterns of glacial erosion and deposition.

scholarly journals Two independent methods for mapping the grounding line of an outlet glacier – example from the Astrolabe Glacier, Terre Adélie, Antarctica

2013 ◽  
Vol 7 (4) ◽  
pp. 3969-4014
Author(s):  
E. Le Meur ◽  
M. Sacchettini ◽  
S. Garambois ◽  
E. Berthier ◽  
A. S. Drouet ◽  
...  
Keyword(s):  
Control Points ◽  
Gps Measurements ◽  
Outlet Glacier ◽  
Ice Surface ◽  
Surface Displacements ◽  
Grounding Line ◽  
Terre Adélie ◽  
Elastic Slab ◽  
Kinematic Approach

Abstract. The grounding line is a key element acting on the dynamics of coastal outlet glaciers. Knowing its position accurately is fundamental for both modelling the glacier dynamics and establishing a benchmark to which one can later refer in case of change. Here we map the grounding line of the Astrolabe Glacier in East Antarctica (66°41´ S; 140°05´ E), using hydrostatic and tidal methods. The first method is based on new surface and ice thickness data from which the line of buoyant flotation is found. We compare this hydrostatic map with kinematic GPS measurements of the tidal response of the ice surface. By detecting the transitions where the ice starts to move vertically in response to the tidal forcing we find control points for the grounding line position along GPS profiles. %If it can be shown that the long-term viscous mechanical behaviour of the ice slab validates the hydrostatic approach, mapping the grounding line from the ice supper surface displacements conversely requires correcting for the rigid elastic slab effect that dominates at tidal frequencies. With the help of a 2-dimensional elastic plate model, rigid elastic deviations are computed and applied to these control points. Once the extent of the grounding zone, the kinematic approach is consistent with the hydrostatic map. These two approaches lead us to propose a grounding line for the Astrolabe Glacier that significantly deviates from those obtained so far from satellite imagery.

Sign in / Sign up

Export Citation Format

Share Document