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mods:
  schema location: http://www.loc.gov/mods/v3 http://www.loc.gov/standards/mods/v3/mods-3-2.xsd
  title info:
    title: Paleogene cooling (55-30 MA) as inferred from oxygen isotope variation within mollusc shells
  title info:
    title: Paleogene cooling (fifty five-thirty mean annual) as inferred from oxygen isotope variation within mollusc shells
  name:
    name part: Kobashi, Takuro
    name part: 1974-
    role:
      role term: creator
  type of resource: text
  genre: bibliography
  origin info:
    place:
      place term: xx
    date issued: 2001
    issuance: monographic
  language:
    language term: eng
  physical description:
    form: print
    form: remote
    extent: xii, 106 leaves : illustrations ; 28 cm.
  abstract: Paleogene cooling (c. 50-30 Ma) started sometime in the early-middle Eocene. This was a time when high-latitude and deep-sea temperatures were significantly warmer than today. This cooling culminated during the earliest Oligocene marked by the sudden appearance of a major continental glacier on Antarctica. We examine this cooling trend by analyzing oxygen isotope variation within mollusc shells from the Gulf Coastal Plain of the southern U.S. Our records show a secular cooling trend of mean annual temperature (MAT) in the Mississippi Embayment from an early Eocene tropical climate (26-27 ⁰C), with a seasonal temperature range (seasonality) of ~6 ⁰C, to an Oligocene paratropical climate (22-23⁰C) with an seasonality of ~8 ⁰C. These temperature records agree well with terrestrial climate proxies. This secular cooling trend, combined with sea-level change, was likely one of the major causes of molluscan turnover in the Mississippi Embayment to cool-tolerant taxa along the Paleogene cooling. Winter temperatures steadily decreased from the middle Eocene to early Oligocene. This contrasts with the sudden winter cooling at Eocene-Oligocene boundary proposed by Ivany et al. (2000). We examined seasonal temperature distribution of the modern marine shelf of the present northern U.S. Gulf Coast. A deeper water temperature model fits well with isotopic temperature profiles derived from fossils shells of the Red Bluff and Yazoo Formations shells, consistent with the paleobathymetry estimates inferred from independent proxies. This reveals that depth effect is one of the major factors controlling seasonality recorded in mollusc shells, resulting in decreasing MAT estimates when temperature stratification exists as in the present ocean. Warm Eocene low-latitude temperatures derived from molluscan oxygen isotope data agree with computer modeling results incorporating higher greenhouse gas concentrations. This supports the contention that the major reason for warm earth climate is …
  note: by Takuro Kobashi.
  note: "Major subject: Geology".
  note: Vita.
  note: Also available online.
  note: Issued also on microfiche from Lange Micrographics.
  note: M.S. Texas A&M University 2001.
  note: Includes bibliographical references (leaves 80-94).
  subject:
    topic: Major geology
  identifier: https://hdl.handle.net/1969.1/ETD-TAMU-2001-THESIS-K64
  related item:
    location:
      url: https://hdl.handle.net/1969.1/ETD-TAMU-2001-THESIS-K64
  record info:
    record content source: TXA
    record creation date: 020603
    record change date: 20220103134523.0
    record identifier: in00001690767