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Constraints on Mars sampling based on models of basaltic flow surfaces and interiorsRecent field observation and numerical modelling of the pattern and origin of vesicle zones and joints in terrestrial basaltic flows has resulted in increased understanding of the processes which affect flow surface morphology. This work has documented the ubiquitous occurrence of three vertical zones in basalt flows: (1) an upper vesicular zone; (2) a middle vesicle-free zone; and (3) a lower vesicular zone. The upper vesicular zone is generally about one-half of the total flow thickness. Computer modeling of the development of these zones confirms that vesicle zonation is a result of the nucleation, growth and rise of bubbles in solidifying lava and can be expected to occur in all basaltic flows. Degradation of basaltic flows, therefore, will produce vesicular blocks until the erosional level reaches the central vesicle-free zone. In addition, observation of terrestrial basaltic flows has shown that most thin (less than 10 m thick) flows have a regular pattern of orthogonal joints in vertical section in which the spacing of joints increases with depth beneath the flow surface. Using these studies we have performed a preliminary analysis of the Viking lander sites.
Document ID
19890008921
Acquisition Source
Legacy CDMS
Document Type
Conference Paper
Authors
Aubele, J. C. (Brown Univ. Providence, RI, United States)
Crumpler, L. S. (Brown Univ. Providence, RI, United States)
Date Acquired
September 5, 2013
Publication Date
January 1, 1988
Publication Information
Publication: Lunar and Planetary Inst., Workshop on Mars Sample Return Science
Subject Category
Lunar And Planetary Exploration
Accession Number
89N18292
Distribution Limits
Public
Copyright
Work of the US Gov. Public Use Permitted.

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