• Login
    View Item 
    •   Home
    • UA Graduate and Undergraduate Research
    • UA Theses and Dissertations
    • Dissertations
    • View Item
    •   Home
    • UA Graduate and Undergraduate Research
    • UA Theses and Dissertations
    • Dissertations
    • View Item
    JavaScript is disabled for your browser. Some features of this site may not work without it.

    Browse

    All of UA Campus RepositoryCommunitiesTitleAuthorsIssue DateSubmit DateSubjectsPublisherJournalThis CollectionTitleAuthorsIssue DateSubmit DateSubjectsPublisherJournal

    My Account

    LoginRegister

    About

    AboutUA Faculty PublicationsUA DissertationsUA Master's ThesesUA Honors ThesesUA PressUA YearbooksUA CatalogsUA Libraries

    Statistics

    Most Popular ItemsStatistics by CountryMost Popular Authors

    Mollusk-Shell Radiocarbon as a Paleoupwelling Proxy in Peru

    • CSV
    • RefMan
    • EndNote
    • BibTex
    • RefWorks
    Thumbnail
    Name:
    azu_etd_10325_sip1_m.pdf
    Size:
    4.391Mb
    Format:
    PDF
    Description:
    azu_etd_10325_sip1_m.pdf
    Download
    Author
    Jones, Kevin Bradley
    Issue Date
    2009
    Keywords
    Argopecten
    Mesodesma
    Peru
    radiocarbon
    reservoir age
    upwelling
    Advisor
    Hodgins, Gregory
    Quade, Jay
    Committee Chair
    Hodgins, Gregory
    Quade, Jay
    
    Metadata
    Show full item record
    Publisher
    The University of Arizona.
    Rights
    Copyright © is held by the author. Digital access to this material is made possible by the University Libraries, University of Arizona. Further transmission, reproduction or presentation (such as public display or performance) of protected items is prohibited except with permission of the author.
    Abstract
    Mollusk shells from Peruvian archaeological middens provide brief (< 5 yr per shell) records of past marine conditions. Marine radiocarbon age, R, is recorded in shell carbonate at the time of precipitation. R varies with changes in upwelling: when radiocarbon-depleted sub-thermocline water wells up, R is large; increased contribution from radiocarbon-enriched surface water (due to seasonal cycles or an El Niño event) reduces R. Are molluscan records of R a useful proxy for Peruvian upwelling? If so, does R from archaeological shells reveal mid-Holocene upwelling changes that constrain the Holocene history of El Niño-Southern Oscillation (ENSO)? Profiles of R along ontogeny from early 20th century Argopecten purpuratus (bay scallop) shells and mid-Holocene A. purpuratus, Mesodesma donacium (surf clam), and Trachycardium procerum (cockle) shells from eight coastal Peru locations show that R varies by up to 530 ± 200 ¹⁴C yr within individual shells. El Niño events are easily detectable in post-1950s shell carbonate due to increased radiocarbon contrast between sub- and super-thermocline water from “bomb carbon,” but R differences between El Niño and La Niña shells from the early 20th century are subtle. Decreasing precision in older shells due to ¹⁴C decay makes detecting El Niño events in the archaeological past using radiocarbon very difficult. Because of intrashell radiocarbon variation, caution is prudent when using marine material for chronometry in variable upwelling environments. Based on modeling, mollusks that grow seasonally rather than year-round can skew long-term average (> 1 yr) R reconstructions by nearly 200 ¹⁴C yr toward R of the preferred growth season. Coldloving M. donacium, for example, records older marine reservoir ages on average than A. purpuratus in the same water, because A. purpuratus grows in both warm and cold conditions. Comparisons of R between species with opposite seasonal growth habits can compound this effect. Because of intrashell R variation, seasonal growth biases, and measurement uncertainties, a change in R due to past ENSO changes would have to be hundreds of ¹⁴C yr or greater to be identifiable. Thus far, clear evidence for such a Holocene change in R has not been seen.
    Type
    text
    Electronic Dissertation
    Degree Name
    Ph.D.
    Degree Level
    doctoral
    Degree Program
    Geosciences
    Graduate College
    Degree Grantor
    University of Arizona
    Collections
    Dissertations

    entitlement

     
    The University of Arizona Libraries | 1510 E. University Blvd. | Tucson, AZ 85721-0055
    Tel 520-621-6442 | repository@u.library.arizona.edu
    DSpace software copyright © 2002-2017  DuraSpace
    Quick Guide | Contact Us | Send Feedback
    Open Repository is a service operated by 
    Atmire NV
     

    Export search results

    The export option will allow you to export the current search results of the entered query to a file. Different formats are available for download. To export the items, click on the button corresponding with the preferred download format.

    By default, clicking on the export buttons will result in a download of the allowed maximum amount of items.

    To select a subset of the search results, click "Selective Export" button and make a selection of the items you want to export. The amount of items that can be exported at once is similarly restricted as the full export.

    After making a selection, click one of the export format buttons. The amount of items that will be exported is indicated in the bubble next to export format.