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Interaction of basaltic dikes and wet lapilli tuff at glaciovolcanic centers: a case study of Sveifluháls, Iceland as a terrestrial analog for dike-cryosphere interaction on Mars

Kagy, Holly M. (2012) Interaction of basaltic dikes and wet lapilli tuff at glaciovolcanic centers: a case study of Sveifluháls, Iceland as a terrestrial analog for dike-cryosphere interaction on Mars. Master's Thesis, University of Pittsburgh. (Unpublished)

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Basaltic dikes emplaced into formerly wet unconsolidated phreatomagmatic tephra deposits were investigated at a glaciovolcanic fissure-fed complex, Sveifluháls, Reykjanes Peninsula SW Iceland. Such dikes serve as excellent terrestrial analogs for high-level basaltic dike-cryosphere interactions on Mars. The dikes revealed several large and small-scale geomorphic and textural characteristics, which would aid satellite and ground-based identification of similar dikes on Mars. The dikes at Sveifluháls typically have narrow (<1.5m wide) coherent interiors of both pillowed and non-pillowed types, but they develop peperitic margins with a geomorphic expression that is often an order of magnitude larger than the coherent dike. This has important implications for recognizing dikes emplaced into the cryosphere, interpreting past climates on Mars, estimating dike widths from remote imagery, and calculating magma flux rates on Mars. Large-scale geomorphological features of the Sveifluháls dikes include local dike-bounded plateaus, adjacent and at lower elevation to phreatomagmatic tephra ridges, with surfaces of dark dike-derived talus. The dikes commonly form narrow steep-sided ridges and less frequently form eroded troughs. The dikes are associated with broad bounding areas of orange to reddish-brown host lapilli tuff (“hydrothermal reddening”), that extends for up to 20m on either side of the dikes, and contrasts with the more typical buff-colored palagonitized lapilli tuff that has not been intruded by dikes. The reddening is likely caused by the presence of concentrically banded zones of possible hematite in vesicles and pore-spaces. Drag-folded, rotated and slumped blocks or domains of the host may extend up to 30m from dike margins. The dikes have a gross tabular morphology, but are locally pillowed or billowy along their margins, and also include finger-like or elongate pillowed projections up to 5m in length from their margins into the host lapilli tuff. Both margins also commonly display 1-3m wide peperitic zones of both blocky and fluidal (including pillow-like) types. Interestingly, the bedding or lamination in the drag folded domains is usually better developed than in the surrounding host deposits. Narrow steep conical mounds of pillow lavas resembling pillow-like haystacks, described from the submarine environment and are interpreted as areas where the dikes emerge on the substrate surface.


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Item Type: University of Pittsburgh ETD
Status: Unpublished
CreatorsEmailPitt UsernameORCID
Kagy, Holly
ETD Committee:
TitleMemberEmail AddressPitt UsernameORCID
Committee ChairSkilling, Ianskilling@pitt.eduSKILLING
Committee MemberHarbert, Williamharbert@pitt.eduHARBERT
Committee MemberRamsey, Michael S.mramsey@pitt.eduMRAMSEY
Date: 26 January 2012
Date Type: Publication
Defense Date: 18 November 2011
Approval Date: 26 January 2012
Submission Date: 9 December 2011
Access Restriction: 1 year -- Restrict access to University of Pittsburgh for a period of 1 year.
Number of Pages: 134
Institution: University of Pittsburgh
Schools and Programs: Dietrich School of Arts and Sciences > Geology and Planetary Science
Degree: MS - Master of Science
Thesis Type: Master's Thesis
Refereed: Yes
Uncontrolled Keywords: basalt, dike, glaciovolcanic, Iceland, terrestrial analog, cryosphere, Mars, peperite, ice, glacier, volcano, pillow haystack, cryolith, sediment deformation, hydrothermal alteration, tindar, Sveifluháls, Reykjanes, phreatomagmatic, tephra, tuff, palagonitized, intrusion, pillow lava
Date Deposited: 26 Jan 2012 19:30
Last Modified: 15 Nov 2016 13:55


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