Terrestrial carbon isotope stratigraphy and mammal turnover during post-PETM hyperthermals in the Bighorn Basin, Wyoming, USA
<p>Paleogene hyperthermals, including the Paleocene–Eocene Thermal Maximum (PETM) and several other smaller events, represent global perturbations to Earth's climate system and are characterized by warmer temperatures, changes in floral and faunal communities, and hydrologic changes. Thes...
| Main Authors: | , , , , |
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| Format: | Article |
| Language: | English |
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Copernicus Publications
2022-04-01
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| Series: | Climate of the Past |
| Online Access: | https://cp.copernicus.org/articles/18/681/2022/cp-18-681-2022.pdf |
| _version_ | 1811314158559297536 |
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| author | S. J. Widlansky R. Secord K. E. Snell A. E. Chew W. C. Clyde |
| author_facet | S. J. Widlansky R. Secord K. E. Snell A. E. Chew W. C. Clyde |
| author_sort | S. J. Widlansky |
| collection | DOAJ |
| description | <p>Paleogene hyperthermals, including the Paleocene–Eocene Thermal
Maximum (PETM) and several other smaller events, represent global
perturbations to Earth's climate system and are characterized by warmer
temperatures, changes in floral and faunal communities, and hydrologic
changes. These events are identified in the geologic record globally by
negative carbon isotope excursions (CIEs), resulting from the input of
isotopically light carbon into Earth's atmosphere. Much about the causes and
effects of hyperthermals remains uncertain, including whether all
hyperthermals were caused by the same underlying processes, how biotic
effects scale with the magnitude of hyperthermals, and why CIEs are larger
in paleosol carbonates relative to marine records. Resolving these questions
is crucial for a full understanding of the causes of hyperthermals and their
application to future climate scenarios. The primary purpose of this study
was to identify early Eocene hyperthermals in the Fifteenmile Creek area of
the south-central Bighorn Basin, Wyoming, USA. This area preserves a
sequence of fluvial floodplain sedimentary rocks containing paleosol
carbonates and an extensive record of fossil mammals. Previous analysis of
faunal assemblages in this area revealed two pulses of mammal turnover and
changes in diversity interpreted to correlate with the ETM2 and H2
hyperthermals that follow the PETM. This was, however, based on long-distance correlation of the fossil record in this area with chemostratigraphic
records from elsewhere in the basin.</p>
<p>We present new carbon isotope stratigraphies using micrite <span class="inline-formula"><i>δ</i><sup>13</sup>C</span>
values from paleosol carbonate nodules preserved in and between richly
fossiliferous mammal localities at Fifteenmile Creek to identify the
stratigraphic positions of ETM2 and H2. Carbon isotope results show that the
ETM2 and H2 hyperthermals, and possibly the subsequent I1 hyperthermal, are
recorded at Fifteenmile Creek. ETM2 and H2 overlap with the two previously
recognized pulses of mammal turnover. The CIEs for these hyperthermals are
also somewhat smaller in magnitude than in more northerly Bighorn Basin
records. We suggest that basin-wide differences in soil moisture and/or
vegetation could contribute to variable CIE amplitudes in this and other
terrestrial records.</p> |
| first_indexed | 2024-04-13T11:06:54Z |
| format | Article |
| id | doaj.art-bcc5fd57c72041f5b5282a147ad90d28 |
| institution | Directory Open Access Journal |
| issn | 1814-9324 1814-9332 |
| language | English |
| last_indexed | 2024-04-13T11:06:54Z |
| publishDate | 2022-04-01 |
| publisher | Copernicus Publications |
| record_format | Article |
| series | Climate of the Past |
| spelling | doaj.art-bcc5fd57c72041f5b5282a147ad90d282022-12-22T02:49:15ZengCopernicus PublicationsClimate of the Past1814-93241814-93322022-04-011868171210.5194/cp-18-681-2022Terrestrial carbon isotope stratigraphy and mammal turnover during post-PETM hyperthermals in the Bighorn Basin, Wyoming, USAS. J. Widlansky0R. Secord1K. E. Snell2A. E. Chew3W. C. Clyde4Department of Earth Sciences, University of New Hampshire, Durham, NH 03824, USADepartment of Earth and Atmospheric Sciences, University of Nebraska – Lincoln, Lincoln, NE 68588, USADepartment of Geological Sciences, University of Colorado Boulder, Boulder, CO 80309, USADepartment of Ecology and Evolutionary Biology, Brown University, Providence, RI 02912, USADepartment of Earth Sciences, University of New Hampshire, Durham, NH 03824, USA<p>Paleogene hyperthermals, including the Paleocene–Eocene Thermal Maximum (PETM) and several other smaller events, represent global perturbations to Earth's climate system and are characterized by warmer temperatures, changes in floral and faunal communities, and hydrologic changes. These events are identified in the geologic record globally by negative carbon isotope excursions (CIEs), resulting from the input of isotopically light carbon into Earth's atmosphere. Much about the causes and effects of hyperthermals remains uncertain, including whether all hyperthermals were caused by the same underlying processes, how biotic effects scale with the magnitude of hyperthermals, and why CIEs are larger in paleosol carbonates relative to marine records. Resolving these questions is crucial for a full understanding of the causes of hyperthermals and their application to future climate scenarios. The primary purpose of this study was to identify early Eocene hyperthermals in the Fifteenmile Creek area of the south-central Bighorn Basin, Wyoming, USA. This area preserves a sequence of fluvial floodplain sedimentary rocks containing paleosol carbonates and an extensive record of fossil mammals. Previous analysis of faunal assemblages in this area revealed two pulses of mammal turnover and changes in diversity interpreted to correlate with the ETM2 and H2 hyperthermals that follow the PETM. This was, however, based on long-distance correlation of the fossil record in this area with chemostratigraphic records from elsewhere in the basin.</p> <p>We present new carbon isotope stratigraphies using micrite <span class="inline-formula"><i>δ</i><sup>13</sup>C</span> values from paleosol carbonate nodules preserved in and between richly fossiliferous mammal localities at Fifteenmile Creek to identify the stratigraphic positions of ETM2 and H2. Carbon isotope results show that the ETM2 and H2 hyperthermals, and possibly the subsequent I1 hyperthermal, are recorded at Fifteenmile Creek. ETM2 and H2 overlap with the two previously recognized pulses of mammal turnover. The CIEs for these hyperthermals are also somewhat smaller in magnitude than in more northerly Bighorn Basin records. We suggest that basin-wide differences in soil moisture and/or vegetation could contribute to variable CIE amplitudes in this and other terrestrial records.</p>https://cp.copernicus.org/articles/18/681/2022/cp-18-681-2022.pdf |
| spellingShingle | S. J. Widlansky R. Secord K. E. Snell A. E. Chew W. C. Clyde Terrestrial carbon isotope stratigraphy and mammal turnover during post-PETM hyperthermals in the Bighorn Basin, Wyoming, USA Climate of the Past |
| title | Terrestrial carbon isotope stratigraphy and mammal turnover during post-PETM hyperthermals in the Bighorn Basin, Wyoming, USA |
| title_full | Terrestrial carbon isotope stratigraphy and mammal turnover during post-PETM hyperthermals in the Bighorn Basin, Wyoming, USA |
| title_fullStr | Terrestrial carbon isotope stratigraphy and mammal turnover during post-PETM hyperthermals in the Bighorn Basin, Wyoming, USA |
| title_full_unstemmed | Terrestrial carbon isotope stratigraphy and mammal turnover during post-PETM hyperthermals in the Bighorn Basin, Wyoming, USA |
| title_short | Terrestrial carbon isotope stratigraphy and mammal turnover during post-PETM hyperthermals in the Bighorn Basin, Wyoming, USA |
| title_sort | terrestrial carbon isotope stratigraphy and mammal turnover during post petm hyperthermals in the bighorn basin wyoming usa |
| url | https://cp.copernicus.org/articles/18/681/2022/cp-18-681-2022.pdf |
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