Simoneau, Elizabeth
(2012)
Eruption and Emplacement Mechanisms and Paleoenvironment of Phreatomagmatic Tephra at Koko Crater Tuff Cone, O’ahu, Hawaii.
Master's Thesis, University of Pittsburgh.
(Unpublished)
Abstract
The emplacement processes of proximal tuff cone deposits are often difficult to distinguish. This thesis focuses on the steep outer flank and surrounding apron deposits of Koko Crater, O’ahu, Hawaii. Four sections were logged in detail and interpreted. The steep outer slope deposits are dominated by slumped pyroclastic fallout deposits, some of which may be directly eruption-fed, and minor pyroclastic density current (PDC) deposits, that are rarely slumped. The lack of slumping of the PDC deposits is interpreted as due to their lower eruption volumes, lower depositional rates, lower water content, and longer transport distances, all of which favor more stable slopes. Slumping is also less common on previously slumped substrate, as slumps typically generate a lower gradient than the primary deposits. The occurrence of PDC deposits overlying fallout deposits, may suggest that the PDC deposits were generated by column collapse (partial, sustained or complete). The flanking apron deposits, i.e. those around the base of the steep outer slopes, are dominated by pyroclastic density current, with minor fallout deposits. Slumping is rare in the flanking apron deposits, probably because of the lower substrate gradients. The increasing abundance of PDC deposits with distance from the vent is most likely due to the longer transport distance compared to the ballistic fallout.
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Details
| Item Type: |
University of Pittsburgh ETD
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| Status: |
Unpublished |
| Creators/Authors: |
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| ETD Committee: |
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| Date: |
26 January 2012 |
| Date Type: |
Publication |
| Defense Date: |
25 July 2011 |
| Approval Date: |
26 January 2012 |
| Submission Date: |
8 December 2011 |
| Access Restriction: |
No restriction; Release the ETD for access worldwide immediately. |
| Number of Pages: |
42 |
| 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: |
phreatomagmatic, tephra, Koko Crater, tuff cone, emplacement |
| Date Deposited: |
26 Jan 2012 21:13 |
| Last Modified: |
15 Nov 2016 13:55 |
| URI: |
http://d-scholarship.pitt.edu/id/eprint/10741 |
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