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dc.contributor.authorCameron, Christopher P.
dc.contributor.authorStone, David B.
dc.date.accessioned2024-10-01T19:56:58Z
dc.date.available2024-10-01T19:56:58Z
dc.date.issued1970-07
dc.identifier.urihttp://hdl.handle.net/11122/15428
dc.descriptionUAG R-213, Scientific Report.en_US
dc.description.abstractA brief review of the general geology and tectonic setting of the Aleutian Island Arc is presented, followed by an account of the paleo-magnetism of selected areas. Paleomagnetic results are presented for Tertiary and Quaternary volcanic rocks from Shemya and Adak Islands. The specimens were collected and measured using standard paleomagnetic methods. Alternating field demagnetization techniques were applied to test the stability of the remanence and to remove unwanted secondary components of magnetization. The variation of the intensity of the NRM with the bulk susceptibility is discussed from the standpoint of the magnetic stability of the rocks. Mid-Late Tertiary and Quaternary specimens satisfy several criteria of magnetic stability in igneous rocks, and derived pole positions are thought to reflect the ambient geomagnetic field at the time of the origin of the rocks. By comparison, the remanent magnetization of Early Tertiary rocks investigated is less stable and yields uncertain results in terms of pole positions. The paleomagnetic results from the various sites are discussed with respect to the background geology of each island. Paleomagnetic pole positions derived from the results are compared with pole positions from other Tertiary and Quaternary sites in North Pacific tectonic belts.en_US
dc.description.sponsorshipThe bulk of the research was supported by the National Science Foundation, Grant No. GA 1216, together with financial aid from State of Alaska funds for the initial field season.en_US
dc.description.tableofcontentsAbstract -- Table of contents -- List of illustrations -- List of tables -- Ch.1. Introduction - Location and description of the study area - Regional geology and tectonic setting – General statement – Seismicity and volcanism – Structure – Geology – Early marine series – Late Tertiary and Quaternary rocks – Summary of the geologic history - Purpose of the study -- Ch.2. Methods and techniques in paleomagnetism – The paleomagnetic theory – Thermoremanent magnetization – Chemical remanent magnetization – Detrital remanent magnetization – Viscous remanent magnetization – Method of investigation – Interpretation of paleomagnetic results -- Ch.3. Paleomagnetism and petrology of Shemya Island – Description and petrography of sampling sites - Paleomagnetic observations I – Directions of remanent magnetization – Mid-late Miocene rocks – Late Cretaceous or Eocene rocks – Paleomagnetic observations II – Susceptibilities, intensities of NRM, and Curie points – Discussion of results -- Ch. 4. Paleomagnetism of northern Adak Island – Description and petrography of sampling sites – Paleomagnetic observations – Late Tertiary and Quaternary rocks – Eocene rocks – Discussion of results -- Ch.5. Conclusions – Interpretation of paleomagnetic results – Quaternary and Plio-Pleistocene results – Plio-Pleistocene and Pliocene results – Plio-Miocene and Miocene results – Paleogene results -- Acknowledgements -- Appendix I. Reference list of Tertiary and Quaternary paleomagnetic directions and pole positions for North Pacific tectonic belts -- References.en_US
dc.language.isoen_USen_US
dc.publisherGeophysical Institute at the University of Alaska Fairbanksen_US
dc.subjectGeologyen_US
dc.subjectPaleomagnetismen_US
dc.subjectAlaskaen_US
dc.subjectAleutian Islandsen_US
dc.titleOutline geology of the Aleutian Islands with paleomagnetic data from Shemya and Adak Islandsen_US
dc.typeReporten_US
refterms.dateFOA2024-10-01T19:57:00Z


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