The petrology, geochemistry, and geochronology of hotspot seamounts in the North Pacific and arc/backarc volcanism on the northern Antarctic Peninsula Public Deposited

http://ir.library.oregonstate.edu/concern/graduate_thesis_or_dissertations/9c67wr28c

Descriptions

Attribute NameValues
Creator
Abstract or Summary
  • Volcanic rocks from hotspots and island arcs/backarcs typically have enriched trace element and isotopic compositions that contain a contribution from subducted oceanic crust. Isotopic and trace element data suggest that the enriched components in hotspot volcanism are ancient subducted sediment and crust, and the enriched components in arc/backarc volcanism are hydrous fluids and melts from the subducting slab. This thesis examines the origins of these enriched components, and how they change in time and space. The Hawaiian-Emperor seamount chain records over 81 million years of volcanism from the Hawaiian hotspot. Seamounts at the old (northern) end of the chain have isotopic compositions more depleted then anything previously reported from the Hawaiian hotspot. Detroit seamount (81 Ma) has the most depleted composition, and was created while an active spreading ridge was close to the hotspot. Proximity to a spreading ridge must have caused the hotspot to entrain and melt more of the depleted upper mantle. The Patton-Murray seamount platform, at the old end of the Cobb hotspot track in the Gulf of Alaska, was volcanically active at 33 Ma, 27 Ma, and 17 Ma. The 33 Ma tholeiitic phase and 27 Ma alkalic phase are related to passage over the hotspot. The 17 Ma phase erupted too late to be directly related to the hotspot, but may have been caused by minor extension along a zone of weakness originally created by passage over the hotspot. On the northern Antarctic Peninsula, volcanism occurred above a subducting slab up to 360 km from the South Shetland Trench. Volcanism on the South Shetland Arc has enriched trace element and isotopic compositions that can be modeled by mixing of subducted sediments and depleted mantle. Backarc basin volcanism in Bransfield Strait contains less of the subducted component, and the most depleted samples are distinguishable from MORB only by their slightly elevated Cs and Pb concentrations. Extreme-backarc volcanism on James Ross Island (360 km from the trench) shows no evidence for the subducted component in its trace element compositions, but its Pb isotopic ratios are affected by Pb from subducted sediment.
Resource Type
Date Available
Date Copyright
Date Issued
Degree Level
Degree Name
Degree Field
Degree Grantor
Commencement Year
Advisor
Committee Member
Academic Affiliation
Non-Academic Affiliation
Subject
Rights Statement
Peer Reviewed
Language
Digitization Specifications
  • File scanned at 300 ppi (Monochrome, 8-bit Grayscale) using ScandAll PRO 1.8.1 on a Fi-6770A in PDF format. CVista PdfCompressor 4.0 was used for pdf compression and textual OCR.
Replaces
Additional Information
  • description.provenance : Approved for entry into archive by Patricia Black(patricia.black@oregonstate.edu) on 2011-09-21T17:13:47Z (GMT) No. of bitstreams: 1 KellerRandallA1996.pdf: 10356824 bytes, checksum: b433bc0048ea1736007fafe9649902cc (MD5)
  • description.provenance : Approved for entry into archive by Patricia Black(patricia.black@oregonstate.edu) on 2011-09-21T17:08:41Z (GMT) No. of bitstreams: 1 KellerRandallA1996.pdf: 10356824 bytes, checksum: b433bc0048ea1736007fafe9649902cc (MD5)
  • description.provenance : Made available in DSpace on 2011-09-21T17:13:47Z (GMT). No. of bitstreams: 1 KellerRandallA1996.pdf: 10356824 bytes, checksum: b433bc0048ea1736007fafe9649902cc (MD5) Previous issue date: 1996-02-01
  • description.provenance : Submitted by Eric Vanderwall (ewscanner@gmail.com) on 2011-09-02T19:27:08Z No. of bitstreams: 1 KellerRandallA1996.pdf: 10356824 bytes, checksum: b433bc0048ea1736007fafe9649902cc (MD5)

Relationships

In Administrative Set:
Last modified: 08/19/2017

Downloadable Content

Download PDF
Citations:

EndNote | Zotero | Mendeley

Items