Abstract/Details

Analysis of enigmatic structures on Mars and Venus and implications for crustal history


2005 2005

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Abstract (summary)

The crustal history of two structurally complex areas on two different planetary bodies is explored, using a combination of image and topographic analysis, kinematic mapping and numerical modeling. Throughout the polygonal terrain of Utopia Planitia, Mars are found circular grabens that are inferred to overlie the rims of buried impact craters. The correspondence of circular grabens and polygonal terrain suggests that their formation may be intrinsically linked. A topographic analysis of circular grabens shows that they bound topographic depressions whose surface relief scales directly with diameter, consistent with a model of polygon formation dependent upon a “wet” cover material. A model is presented for why the circular grabens are sometimes comprised of two nested ring fractures. The model results imply that cover material in the southwestern polygonal area of Utopia may range from 1–2 km thick and strongly favors a wet sedimentary origin for the cover material. A systematic study of the topography of quasi-circular depressions (QCDs) around the Utopia Basin is presented. The results of this study support the assumption that QCDs are the surface representations of buried impact craters. There are ridges radial to Irnini Mons, Venus, revealed by high resolution mapping at 75 m/pixel. Unlike the unit of arcuate ridges directly south, these ridges are on top of the Irini flows and cannot be an older feature. Analytical modeling of the perturbation of regional stresses around a pressurized magma chamber conduit shows that in the presence of the regional north-south compression, responsible for the regional set of east-west trending wrinkle ridges, circumferential stresses can be compressive. Directional models of Venus' tectonic history argue that all wrinkle ridge formation occurred prior to the formation of large volcanoes. Thus, continuing the regional compression that formed the wrinkle ridges through the volcano building event contradicts directionalism and supports non-directional tectonic models.

Indexing (details)


Subject
Geology
Classification
0372: Geology
Identifier / keyword
Earth sciences; Irnini Mons; Mars; Utopia Planitia; Venus
Title
Analysis of enigmatic structures on Mars and Venus and implications for crustal history
Author
Buczkowski, Debra L.
Number of pages
102
Publication year
2005
Degree date
2005
School code
0118
Source
DAI-B 66/06, Dissertation Abstracts International
Place of publication
Ann Arbor
Country of publication
United States
ISBN
9780542197468, 0542197464
Advisor
McGill, George E.
University/institution
University of Massachusetts Amherst
University location
United States -- Massachusetts
Degree
Ph.D.
Source type
Dissertations & Theses
Language
English
Document type
Dissertation/Thesis
Dissertation/thesis number
3179860
ProQuest document ID
304997049
Copyright
Database copyright ProQuest LLC; ProQuest does not claim copyright in the individual underlying works.
Document URL
http://search.proquest.com/docview/304997049
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