<rdf:RDF xmlns:rdf="http://www.w3.org/1999/02/22-rdf-syntax-ns#" xmlns:skos="http://www.w3.org/2004/02/skos/core#" xmlns:gcmd="https://gcmd.earthdata.nasa.gov/kms#" xmlns:dcterms="http://purl.org/dc/terms/" xml:base="https://gcmd.earthdata.nasa.gov/kms/concept/">
  <gcmd:gcmd>
    <gcmd:termsOfUse>https://cdn.earthdata.nasa.gov/conduit/upload/5182/KeywordsCommunityGuide_Baseline_v1_SIGNED_FINAL.pdf</gcmd:termsOfUse>
    <gcmd:keywordVersion>23.7</gcmd:keywordVersion>
    <gcmd:schemeVersion>2026-04-15T10:53:30.610Z</gcmd:schemeVersion>
    <gcmd:viewer>https://gcmd.earthdata.nasa.gov/KeywordViewer/scheme/sciencekeywords/a65ec029-86a7-4c3b-b2b3-ee26353aaf36</gcmd:viewer>
  </gcmd:gcmd>
  <skos:Concept rdf:about="a65ec029-86a7-4c3b-b2b3-ee26353aaf36">
    <skos:broader rdf:resource="45325a01-2522-48d3-bffa-0edf1a934d48"/>
    <skos:prefLabel xml:lang="en">OXYGEN ISOTOPES</skos:prefLabel>
    <gcmd:reference gcmd:text="Bradley, R.S. 1999. Paleoclimatology: Reconstructing Climates of the Quaternary, 2nd edition. Harcourt Academic Press (especially Chapter 6.3)." xml:lang="en"/>
    <skos:definition xml:lang="en">Isotopes of oxygen (O-18, O-16, O-13) are found in calcium carbonate in seawater. The production of O18 is highly dependent on temperature. The oxygenisotope record in marine sediments varies locally with temperature and globallywith variations in continental ice volume. Oxygen isotope analyses have beencarried out on deep sea cores from areas of calcareous sedimentation throughoutthe world and similar variations in O18 are recorded everywhere. The O18 signalis that of ice volume changes on the continents and concomitant changes in theisotopic content of the oceans.</skos:definition>
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