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<front>
<journal-meta>
<journal-id journal-id-type="publisher">EGUsphere</journal-id>
<journal-title-group>
<journal-title>EGUsphere</journal-title>
<abbrev-journal-title abbrev-type="publisher">EGUsphere</abbrev-journal-title>
<abbrev-journal-title abbrev-type="nlm-ta">EGUsphere</abbrev-journal-title>
</journal-title-group>
<publisher><publisher-name>Copernicus Publications</publisher-name>
<publisher-loc>Göttingen, Germany</publisher-loc>
</publisher>
</journal-meta>
<article-meta>
<article-id pub-id-type="doi">10.5194/egusphere-2026-5607</article-id>
<title-group>
<article-title>Characterization of complex basal layering in an ancient Allan Hills ice core</article-title>
</title-group>
<contrib-group><contrib contrib-type="author" xlink:type="simple"><name name-style="western"><surname>Kirkpatrick</surname>
<given-names>Liam R.</given-names>
<ext-link>https://orcid.org/0000-0002-6476-5331</ext-link>
</name>
<xref ref-type="aff" rid="aff1">
<sup>1</sup>
</xref>
</contrib>
<contrib contrib-type="author" xlink:type="simple"><name name-style="western"><surname>Chalif</surname>
<given-names>Jacob I.</given-names>
<ext-link>https://orcid.org/0000-0001-5401-7148</ext-link>
</name>
<xref ref-type="aff" rid="aff2">
<sup>2</sup>
</xref>
<xref ref-type="aff" rid="aff3">
<sup>3</sup>
</xref>
</contrib>
<contrib contrib-type="author" xlink:type="simple"><name name-style="western"><surname>Brandis</surname>
<given-names>Derek</given-names>
<ext-link>https://orcid.org/0000-0002-0626-0327</ext-link>
</name>
<xref ref-type="aff" rid="aff4">
<sup>4</sup>
</xref>
</contrib>
<contrib contrib-type="author" xlink:type="simple"><name name-style="western"><surname>Carter</surname>
<given-names>Austin</given-names>
<ext-link>https://orcid.org/0000-0001-5153-2507</ext-link>
</name>
<xref ref-type="aff" rid="aff5">
<sup>5</sup>
</xref>
</contrib>
<contrib contrib-type="author" xlink:type="simple"><name name-style="western"><surname>Choi</surname>
<given-names>Alissa</given-names>
<ext-link>https://orcid.org/0009-0003-5589-0899</ext-link>
</name>
<xref ref-type="aff" rid="aff6">
<sup>6</sup>
</xref>
</contrib>
<contrib contrib-type="author" xlink:type="simple"><name name-style="western"><surname>Davidge</surname>
<given-names>Lindsey</given-names>
</name>
<xref ref-type="aff" rid="aff1">
<sup>1</sup>
</xref>
</contrib>
<contrib contrib-type="author" xlink:type="simple"><name name-style="western"><surname>Handley</surname>
<given-names>Michael J.</given-names>
</name>
<xref ref-type="aff" rid="aff7">
<sup>7</sup>
</xref>
</contrib>
<contrib contrib-type="author" xlink:type="simple"><name name-style="western"><surname>Harris Stuart</surname>
<given-names>Romilly</given-names>
</name>
<xref ref-type="aff" rid="aff10">
<sup>10</sup>
</xref>
</contrib>
<contrib contrib-type="author" xlink:type="simple"><name name-style="western"><surname>Hishamunda</surname>
<given-names>Valens</given-names>
</name>
<xref ref-type="aff" rid="aff5">
<sup>5</sup>
</xref>
</contrib>
<contrib contrib-type="author" xlink:type="simple"><name name-style="western"><surname>Jongebloed</surname>
<given-names>Ursula A.</given-names>
</name>
<xref ref-type="aff" rid="aff8">
<sup>8</sup>
</xref>
<xref ref-type="aff" rid="aff9">
<sup>9</sup>
</xref>
</contrib>
<contrib contrib-type="author" xlink:type="simple"><name name-style="western"><surname>Kalk</surname>
<given-names>Michael</given-names>
</name>
<xref ref-type="aff" rid="aff10">
<sup>10</sup>
</xref>
</contrib>
<contrib contrib-type="author" xlink:type="simple"><name name-style="western"><surname>Korotkikh</surname>
<given-names>Elena V.</given-names>
</name>
<xref ref-type="aff" rid="aff7">
<sup>7</sup>
</xref>
</contrib>
<contrib contrib-type="author" xlink:type="simple"><name name-style="western"><surname>Lowes-Bicay</surname>
<given-names>Haley</given-names>
</name>
<xref ref-type="aff" rid="aff1">
<sup>1</sup>
</xref>
<xref ref-type="aff" rid="aff11">
<sup>11</sup>
</xref>
</contrib>
<contrib contrib-type="author" xlink:type="simple"><name name-style="western"><surname>Marks-Peterson</surname>
<given-names>Julia</given-names>
<ext-link>https://orcid.org/0009-0005-5556-6348</ext-link>
</name>
<xref ref-type="aff" rid="aff10">
<sup>10</sup>
</xref>
</contrib>
<contrib contrib-type="author" xlink:type="simple"><name name-style="western"><surname>Schauer</surname>
<given-names>Andrew J.</given-names>
<ext-link>https://orcid.org/0000-0002-5941-5396</ext-link>
</name>
<xref ref-type="aff" rid="aff1">
<sup>1</sup>
</xref>
</contrib>
<contrib contrib-type="author" xlink:type="simple"><name name-style="western"><surname>Stoll</surname>
<given-names>Nicolas</given-names>
<ext-link>https://orcid.org/0000-0002-3219-8395</ext-link>
</name>
<xref ref-type="aff" rid="aff1">
<sup>1</sup>
</xref>
<xref ref-type="aff" rid="aff12">
<sup>12</sup>
</xref>
</contrib>
<contrib contrib-type="author" xlink:type="simple"><name name-style="western"><surname>Tipton</surname>
<given-names>Lilly</given-names>
</name>
<xref ref-type="aff" rid="aff2">
<sup>2</sup>
</xref>
</contrib>
<contrib contrib-type="author" xlink:type="simple"><name name-style="western"><surname>Aarons</surname>
<given-names>Sarah</given-names>
<ext-link>https://orcid.org/0000-0002-3580-0820</ext-link>
</name>
<xref ref-type="aff" rid="aff11">
<sup>11</sup>
</xref>
<xref ref-type="aff" rid="aff13">
<sup>13</sup>
</xref>
</contrib>
<contrib contrib-type="author" xlink:type="simple"><name name-style="western"><surname>Brook</surname>
<given-names>Edward</given-names>
<ext-link>https://orcid.org/0000-0001-5438-0115</ext-link>
</name>
<xref ref-type="aff" rid="aff10">
<sup>10</sup>
</xref>
</contrib>
<contrib contrib-type="author" xlink:type="simple"><name name-style="western"><surname>Buizert</surname>
<given-names>Christo</given-names>
<ext-link>https://orcid.org/0000-0002-2227-1747</ext-link>
</name>
<xref ref-type="aff" rid="aff10">
<sup>10</sup>
</xref>
</contrib>
<contrib contrib-type="author" xlink:type="simple"><name name-style="western"><surname>Cole-Dai</surname>
<given-names>Jihong</given-names>
<ext-link>https://orcid.org/0000-0003-0921-5916</ext-link>
</name>
<xref ref-type="aff" rid="aff4">
<sup>4</sup>
</xref>
</contrib>
<contrib contrib-type="author" xlink:type="simple"><name name-style="western"><surname>Higgins</surname>
<given-names>John</given-names>
</name>
<xref ref-type="aff" rid="aff5">
<sup>5</sup>
</xref>
</contrib>
<contrib contrib-type="author" xlink:type="simple"><name name-style="western"><surname>Koffman</surname>
<given-names>Bess G.</given-names>
</name>
<xref ref-type="aff" rid="aff14">
<sup>14</sup>
</xref>
</contrib>
<contrib contrib-type="author" xlink:type="simple"><name name-style="western"><surname>Osterberg</surname>
<given-names>Erich C.</given-names>
</name>
<xref ref-type="aff" rid="aff2">
<sup>2</sup>
</xref>
</contrib>
<contrib contrib-type="author" xlink:type="simple"><name name-style="western"><surname>Steig</surname>
<given-names>Eric J.</given-names>
<ext-link>https://orcid.org/0000-0002-8191-5549</ext-link>
</name>
<xref ref-type="aff" rid="aff1">
<sup>1</sup>
</xref>
</contrib>
<contrib contrib-type="author" xlink:type="simple"><name name-style="western"><surname>Shackleton</surname>
<given-names>Sarah</given-names>
</name>
<xref ref-type="aff" rid="aff15">
<sup>15</sup>
</xref>
</contrib>
<contrib contrib-type="author" xlink:type="simple"><name name-style="western"><surname>Fudge</surname>
<given-names>Tyler Jeffrey</given-names>
<ext-link>https://orcid.org/0000-0002-6818-7479</ext-link>
</name>
<xref ref-type="aff" rid="aff1">
<sup>1</sup>
</xref>
</contrib>
</contrib-group><aff id="aff1">
<label>1</label>
<addr-line>Department of Earth and Space Sciences, University of Washington, Seattle, WA 98195, USA</addr-line>
</aff>
<aff id="aff2">
<label>2</label>
<addr-line>Department of Earth and Planetary Sciences, Dartmouth College, Hanover, NH 03755, USA</addr-line>
</aff>
<aff id="aff3">
<label>3</label>
<addr-line>Department of Atmospheric and Climate Science, University of Washington, Seattle, WA 98195, USA</addr-line>
</aff>
<aff id="aff4">
<label>4</label>
<addr-line>Department of Chemistry, Biochemistry, &amp; Physics, South Dakota State University, Brookings, SD 57007, USA</addr-line>
</aff>
<aff id="aff5">
<label>5</label>
<addr-line>Department of Geosciences, Princeton University, Princeton, NJ 08544, USA</addr-line>
</aff>
<aff id="aff6">
<label>6</label>
<addr-line>Department of Geoscience, University of Wisconsin–Madison, Madison, WI 53706, USA</addr-line>
</aff>
<aff id="aff7">
<label>7</label>
<addr-line>Climate Change Institute, University of Maine, Orono, ME 04469, USA</addr-line>
</aff>
<aff id="aff8">
<label>8</label>
<addr-line>Department of Civil and Environmental Engineering, Massachusetts Institute of Technology, Cambridge, MA, USA</addr-line>
</aff>
<aff id="aff9">
<label>9</label>
<addr-line>Department of Earth, Atmospheric, and Planetary Sciences, Massachusetts Institute of Technology, Cambridge, MA 02139,  USA</addr-line>
</aff>
<aff id="aff10">
<label>10</label>
<addr-line>College of Earth, Ocean, and Atmospheric Sciences, Oregon State University, Corvallis, OR 97331, USA</addr-line>
</aff>
<aff id="aff11">
<label>11</label>
<addr-line>Scripps Institution of Oceanography, University of California San Diego, La Jolla, CA 92093, USA</addr-line>
</aff>
<aff id="aff12">
<label>12</label>
<addr-line>Department of Environmental Sciences, Informatics and Statistics, Ca’Foscari University of Venice, Venice, Italy</addr-line>
</aff>
<aff id="aff13">
<label>13</label>
<addr-line>Lamont-Doherty Earth Observatory, Columbia University, Palisades, NY 10964, USA</addr-line>
</aff>
<aff id="aff14">
<label>14</label>
<addr-line>Department of Earth Sciences, Colby College, Waterville, ME 04901, USA</addr-line>
</aff>
<aff id="aff15">
<label>15</label>
<addr-line>Woods Hole Oceanographic Institution, Woods Hole, MA 02543, USA</addr-line>
</aff>
<pub-date pub-type="epub">
<day>16</day>
<month>10</month>
<year>2026</year>
</pub-date>
<volume>2026</volume>
<fpage>1</fpage>
<lpage>39</lpage>
<permissions>
<copyright-statement>Copyright: &#x000a9; 2026 Liam R. Kirkpatrick et al.</copyright-statement>
<copyright-year>2026</copyright-year>
<license license-type="open-access">
<license-p>This work is licensed under the Creative Commons Attribution 4.0 International License. To view a copy of this licence, visit <ext-link ext-link-type="uri"  xlink:href="https://creativecommons.org/licenses/by/4.0/">https://creativecommons.org/licenses/by/4.0/</ext-link></license-p>
</license>
</permissions>
<self-uri xlink:href="https://egusphere.copernicus.org/preprints/2026/egusphere-2026-5607/">This article is available from https://egusphere.copernicus.org/preprints/2026/egusphere-2026-5607/</self-uri>
<self-uri xlink:href="https://egusphere.copernicus.org/preprints/2026/egusphere-2026-5607/egusphere-2026-5607.pdf">The full text article is available as a PDF file from https://egusphere.copernicus.org/preprints/2026/egusphere-2026-5607/egusphere-2026-5607.pdf</self-uri>
<abstract>
<p>Ice cores from the Allan Hills blue ice area in East Antarctica contain the oldest known direct samples of the ancient atmosphere, with ages extending through the Pleistocene (0.01&amp;ndash;2.58 Ma), Pliocene (2.58&amp;ndash;5.33 Ma), and into the late Miocene (&amp;gt;5.33 Ma). These cores are challenging to interpret because their timescales are compressed and discontinuous; understanding sub-meter-scale layering and stratigraphic continuity is therefore critical for robust climate interpretation. To provide insight into the composition and origins of sub-meter-scale layering in Allan Hills ice, we apply a coordinated sampling approach to two sections of the ALHIC1901 ice core, located 3 m and 5 m above the bed and dated to 1.3&amp;ndash;1.8 Ma. This study is the first high-resolution characterization of ice of this age in the Allan Hills, and so provides critical insight into the composition and variability within this ice. First, we use three-dimensional electrical conductivity measurements (3D ECM) to identify planar and steeply dipping layers across the large-diameter (241 mm) cores. We then construct a common dip-adjusted depth scale and apply it to measurements of trace elements, ions, particle size and concentration, greenhouse gases, major gas (N&lt;sub&gt;2&lt;/sub&gt;, O&lt;sub&gt;2&lt;/sub&gt;) isotope and elemental ratios, water-isotope ratios, and &lt;sup&gt;40&lt;/sup&gt;Ar&lt;sub&gt;atm&lt;/sub&gt; ages. Replicate measurements from different positions within the core cross section agree closely once aligned on the dip-adjusted depth scale, indicating coherent planar layering. Furthermore, &lt;sup&gt;40&lt;/sup&gt;Ar&lt;sub&gt;atm&lt;/sub&gt; dating demonstrates that the layers are consistent with isochronal layering at dating precision. Age differences can exceed 100 kyr across decimeter-scale layering. While some climate signal is preserved across layers in water isotope ratios, we conclude that the primary source of variability across most measurements in this near-bed Allan Hills ice is incorporated basal material. Multiple layers enriched in basal material exhibit distinct properties, suggesting that basal material is incorporated into multiple discrete ice packets rather than a single homogeneous unit. This study demonstrates a novel approach &amp;mdash; using high-resolution, multi-proxy measurements to characterize steeply dipping layering &amp;mdash; with broad applicability to future work at the Allan Hills and other ice core sites.</p>
</abstract>
<counts><page-count count="39"/></counts>
<funding-group>
<award-group id="gs1">
<funding-source>National Science Foundation</funding-source>
<award-id>NSF-2019719</award-id>
<award-id>OPP-2149518</award-id>
<award-id>OPP-2024132</award-id>
</award-group>
<award-group id="gs2">
<funding-source>W. M. Keck Foundation</funding-source>
<award-id>2024-2309</award-id>
</award-group>
<award-group id="gs3">
<funding-source>Horizon 2020</funding-source>
<award-id>101146092</award-id>
</award-group>
</funding-group>
</article-meta>
</front>
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<back>
</back>
</article>