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Quantitative Investigations of Polygonal Ground in Continental Antarctica: Terrestrial Analogues for Polygons on Mars

Sassenroth, C. and Hauber, Ernst and de Vera, Jean Pierre Paul and Schmitz, Nicole (2017) Quantitative Investigations of Polygonal Ground in Continental Antarctica: Terrestrial Analogues for Polygons on Mars. In: Geophysical Research Abstracts, 19, EGU2017-16618. European Geosciences Union General Assembly 2017, 23–28 April, 2017, Wien, Österreich.

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Official URL: http://meetingorganizer.copernicus.org/EGU2017/EGU2017-16618-2.pdf

Abstract

Polygonally fractured ground is widespread at middle and high latitudes on Mars. The latitude-dependence and the morphologic similarity to terrestrial patterned ground in permafrost regions may indicate a formation as thermal contraction cracks, but the exact formation mechanisms are still unclear. In particular, it is debated whether freeze-thaw processes and liquid water are required to generate the observed features. This study quantitatively investigates polygonal networks in ice-free parts of continental Antarctica to help distinguishing between different hypotheses of their origin on Mars. The study site is located in the Helliwell Hills in Northern Victoria Land (�71.73�S/161.38�E) and was visited in the framework of the GANOVEX XI expedition during the austral summer of 2015/2016. The local bedrock consists mostly of sediments (sandstones) of the Beacon Supergroup and mafic igneous intrusions (Ferrar Dolerites). The surfaces are covered by glacial drift consisting of clasts with diverse lithologies. Thermal contraction cracks are ubiquitous.We mapped polygons in the northern part of Helliwell Hills in a GIS environment on the basis of high-resolution satellite images with a pixel size of �50 cm. The measured spatial parameters include polygon area, perimeter, length, width, circularity and aspect.We also analyzed the connectivity of enclosed polygons within a polygon network. The polygons do not display significant local relief, but overall the polygon centers are slightly higher than the bounding cracks (i.e. high-center polygons). Sizes of polygons can vary widely, dependent on the geographical location, between 10m2 and >900m2. In planar and level areas, thermal contraction cracks tend to be well connected as hexagonal or irregular polygonal networks without a preferred alignment. In contrast, polygonal networks on slopes form elongated, orthogonal primary cracks, which are either parallel or transverse to the steepest topographic gradient. During fieldwork, excavations were made in the center of polygons and across the bounding cracks. Typically, the uppermost �40 cm of regolith are dry and unconsolidated. Below that, there is commonly a sharp transition to ice-cemented material or very clear ice with no bubbles. Soil profiles were recorded, and sediment samples were taken and analyzed for their grain size composition with laser diffractometric measurement methods. External factors such as slope gradient and orientation, insolation and composition of surface and subsurface materials were included in the analysis.

Item URL in elib:https://elib.dlr.de/116502/
Document Type:Conference or Workshop Item (Speech)
Title:Quantitative Investigations of Polygonal Ground in Continental Antarctica: Terrestrial Analogues for Polygons on Mars
Authors:
AuthorsInstitution or Email of AuthorsAuthors ORCID iD
Sassenroth, C.dlr-pfUNSPECIFIED
Hauber, Ernsternst.hauber (at) dlr.dehttps://orcid.org/0000-0002-1375-304X
de Vera, Jean Pierre Pauljean-pierre.devera (at) dlr.deUNSPECIFIED
Schmitz, Nicolenicole.schmitz (at) dlr.deUNSPECIFIED
Date:2017
Journal or Publication Title:Geophysical Research Abstracts
Refereed publication:No
Open Access:Yes
Gold Open Access:No
In SCOPUS:No
In ISI Web of Science:No
Volume:19
Page Range:EGU2017-16618
Status:Published
Keywords:Mars, Antarctica, polygons, water, ice, climate, terrestrial analogues, permafrost
Event Title:European Geosciences Union General Assembly 2017
Event Location:Wien, Österreich
Event Type:international Conference
Event Dates:23–28 April, 2017
Organizer:European Geosciences Union
HGF - Research field:Aeronautics, Space and Transport
HGF - Program:Space
HGF - Program Themes:Space Science and Exploration
DLR - Research area:Raumfahrt
DLR - Program:R EW - Erforschung des Weltraums
DLR - Research theme (Project):Project MARS-EXPRESS / HRSC
Location: Berlin-Adlershof
Institutes and Institutions:Institute of Planetary Research > Planetary Geology
Institute of Planetary Research > Leitungsbereich PF
Deposited By: Hauber, Ernst
Deposited On:05 Dec 2017 12:34
Last Modified:31 Jul 2019 20:13

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