Wilkes Land Glacial History (WEGA)
Entry ID:
ASAC_1044
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Summary
Abstract:
A collaborative Italian/Australian marine geoscience research voyage to the George Vth Land sector of the East Antarctic continental margin was carried out between 11th February and 20th March, 2000, on board the of the RV Tangaroa. The cost of the expedition was shared jointly by the Italian and Australian National Antarctic Research Programs. Twenty four scientific personnel from 13 ... institutions participated in the expedition.
The geophysical data collected includes a total of 1827 km of multi-channel seismic data and 562 km of Chirper sonar data. A total of 11 gravity cores, 28 piston cores, 18 surface grabs and 11 short trigger cores were collected on the voyage. Water profile (CTD) measurements and water samples were collected at nine stations and seabed bottom photographs were made at 11 stations.
The expedition discovered and mapped a shelf sediment drift deposit covering about 400 km2 lying in an >800m deep section of the George Vth basin west of the Mertz Glacier. It is a true 'drift' deposit, since these sediments exhibit a patchy distribution, large-scale bedforms, contain foreset bedding and display a depositional architecture indicative of contour-parallel sediment transport. A significant observation is that the drift thins to the north into an acoustically-transparent veneer; this observation implies that the drift is sourced from the outer continental shelf, with sediment being transported landwards, across the shelf and into an 850m deep inner shelf basin. The 'Mertz Drift' is over 35 m thick and core samples demonstrate that it is composed of laminated, anoxic, gelatinous olive green, silicious mud and diatom ooze (SMO). Preliminary shipboard counts of the laminae suggest a thickness of from 4 to 20mm, with a mean of about 7mm. While the lower sediments are laminated, there is a 20 to 50cm thick sandy drape at the surface over the whole of the drift. This suggests that a recent (late Holocene) change in the depositional environment has occurred, possibly related to changes in the extent of the nearby Mertz Glacier tongue, current regime and/or to the persistence of sea ice over the shelf area.
Multi-channel seismic data show the occurrence of foreset beds at the shelf break, interpreted as having been deposited by ice streams that grounded on the outer shelf during glacial maxima. On the shelf, the seismic character of the seafloor exhibits highly reflective, parabolic reflectors suggestive of crystalline basement, cropping out at the seafloor. Northwards of these basement outcrops, the water depth increases to over 1,100 m which is the George Vth Basin. The basin coincides with an abrupt transition in seismic character from acoustic basement in the south to seaward (northeasterly) dipping reflectors. On the continental rise, seismic sections were taken across a contourite drift deposit and submarine canyon system in 2500 to 3500 m water depth. Piston cores were collected along the profile of one drift deposit which gave a preliminary Mid-Pliocene age to truncated strata that crop out on the drift's steeper lee side. These data will provide useful site-survey information in support of a proposal sent to the Ocean Drilling Program under the auspices of the SCAR-ANTOSTRAT project for drilling key sites along the Antarctic margin. 
Related URL
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Description:
Italian metadata record for the same project
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Geographic Coverage
(Click for Interactive Map)
Spatial coordinates
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N: -64.0
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S: -67.5
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E: 146.0
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W: 142.0
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Min Depth:
100
Max Depth:
3500
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Temporal Coverage
Start Date:
2000-09-30
Stop Date:
2001-03-31
Quality
The first step in creating a multihazard surface is to isolate those areas that are the most at-risk for mortality (deciles 8-10) for each of the hazards considered in the study (cyclones, droughts, earthquakes, floods, landslides, and volcanoes). Three categorical hazard surfaces representing the highest mortality risks are created from combinations of the single hazard surfaces. The hazard ... categories are as follows: drought: drought
seismic: earthquakes and volcanoes
hydro: cyclones, floods, and landslides
Each of the hazard category surfaces is binary. To produce the multihazard surface, each of the categorical surfaces is combined into a single surface. Each grid cell of the multihazard surface is attributed with information regarding its value in each of the hazard categories (items Drought3, Seismic3, and Hydro3). This sequence of values forms a unique class of multihazardness.
The population per grid cell is based on Gridded Population of the World, Version 3 (GPWv3). The area per grid cell, in square kilometers, is calculated by subtracting from the area of the grid cell those portions that are permanently inundated. Identification of permanently inundated areas utilizes VMAP(0) data. VMAP(0) data is also used to identify major roads and railroads.
Building upon a methodology proposed by Sachs et al. (2003), a Gross Domestic Product (GDP) value (US$, 2000, purchase power parity adjusted (PPP)) is estimated on a per grid cell basis. First, the contribution of subnational units to national GDP utilizing data of varied origin. The ratio of the subnational production to the national GDP is the contribution rate. To standardize across countries, these contribution rates are applied to published World Bank GDP estimates to determine GDP values of the subnational units.
The standardized, subnational GDP estimate is divided by the total population within the subnational unit to produce a spatially variable per capita GDP estimate.
Access Constraints
None
Use Constraints
The Trustees of Columbia University in the City of New York, Center for Hazards and Risk Research (CHRR), and International Bank for Reconstruction and Development/The World Bank hold the copyright of this dataset. Users are prohibited from any commercial, non-free resale, or redistribution without explicit written permission from CHRR, CIESIN, and The World Bank. Users should acknowledge CHRR, CIESIN, and The World Bank as the source used in the creation of any reports, publications, new datasets, derived products, or services resulting from the use of this dataset. CHRR, CIESIN, and The World Bank also request reprints of any publications and notification of any redistribution efforts.
Data Set Progress
COMPLETE
Distribution
Distribution Media:
Online FTP
Distribution Format:
ASCII
Fees:
0
Distribution Media:
Online FTP
Distribution Format:
DBF
Fees:
0
Distribution Media:
Online HTTP
Distribution Format:
PDF
Fees:
0
Distribution Media:
Online HTTP
Distribution Format:
PNG
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Personnel
Role:
TECHNICAL CONTACT
Phone:
+1 845-365-8920
Fax:
+1 845-365-8922
Email:
ciesin.info at ciesin.columbia.edu
Contact Address:
61 Route 9W, P.O. Box 1000
City:
Palisades
Province or State:
NY
Postal Code:
10964
Country:
USA
Role:
DIF AUTHOR
Phone:
+1 845-365-8988
Fax:
+1 845-365-8922
Email:
metadata at ciesin.columbia.edu
Contact Address:
61 Route 9W, P.O. Box 1000
City:
Palisades
Province or State:
New York
Postal Code:
10964
Country:
USA
Publications/References
Center for Hazards and Risk Research (CHRR)/Columbia University, Center for International Earth Science Information Network (CIESIN)/Columbia University, and International Bank for Reconstruction and Development/The World Bank (2005), Global Multihazard Frequency and Distribution, Center for Hazards and Risk Research (CHRR)/Columbia University, Palisades, NY, http://sedac.ciesin.columbia.edu/data/set/ndh-multihazard-frequency... Center for Hazards and Risk Research (CHRR)/Columbia University, Center for International Earth Science Information Network (CIESIN)/Columbia University, and International Bank for Reconstruction and Development/The World Bank (2005), Global Multihazard Proportional Economic Loss Risk Deciles, Center for Hazards and Risk Research (CHRR)/Columbia University, Palisades, NY, http://sedac.ciesin.columbia.edu/data/set/ndh-multihazard-proportio... Center for Hazards and Risk Research (CHRR)/Columbia University, Center for International Earth Science Information Network (CIESIN)/Columbia University, and International Bank for Reconstruction and Development/The World Bank (2005), Global Multihazard Total Economic Loss Risk Deciles, Center for Hazards and Risk Research (CHRR)/Columbia University, Palisades, NY, http://sedac.ciesin.columbia.edu/data/set/ndh-multihazard-total-eco...
Creation and Review Dates
DIF Creation Date:
2005-10-11
Last DIF Revision Date:
2013-02-14
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