Multi-proxy speleothem-based reconstruction of mid-MIS 3 climate in South Africa
<p>The southern coast of South Africa displays a highly dynamical climate as it is at the convergence of the Atlantic and Indian oceans, and it is located near the subtropical/temperate zone boundary with seasonal influence of easterlies and westerlies. The region hosts some key archeological...
| Main Authors: | , , , , , , , , , |
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| Format: | Article |
| Language: | English |
| Published: |
Copernicus Publications
2023-09-01
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| Series: | Climate of the Past |
| Online Access: | https://cp.copernicus.org/articles/19/1847/2023/cp-19-1847-2023.pdf |
| Summary: | <p>The southern coast of South Africa displays a highly
dynamical climate as it is at the convergence of the Atlantic and
Indian oceans, and it is located near the subtropical/temperate zone boundary
with seasonal influence of easterlies and westerlies. The region hosts some key
archeological sites with records of significant cognitive, technological and
social developments. Reconstructions of the state and variability of past
climate and environmental conditions around sites of archeological
significance can provide crucial context for understanding the evolution of
early humans. Here we present a short but high-resolution record of
hydroclimate and temperature in South Africa. Our reconstructions are based
on trace elements, calcite and fluid inclusion stable isotopes, as well as fluid
inclusion microthermometry, from a speleothem collected in Bloukrantz cave,
in the De Hoop Nature Reserve in the southern Cape region of South Africa.</p>
<p>Our record covers the time period from 48.3 to 45.2 ka during marine isotope
stage 3. Both <span class="inline-formula"><i>δ</i><sup>18</sup></span>O<span class="inline-formula"><sub>c</sub></span> and <span class="inline-formula"><i>δ</i><sup>13</sup></span>C<span class="inline-formula"><sub>c</sub></span> show strong variability
and covary with <span class="inline-formula"><math xmlns="http://www.w3.org/1998/Math/MathML" id="M5" display="inline" overflow="scroll" dspmath="mathml"><mrow><mi mathvariant="normal">Sr</mi><mo>/</mo><mi mathvariant="normal">Ca</mi></mrow></math><span><svg:svg xmlns:svg="http://www.w3.org/2000/svg" width="33pt" height="14pt" class="svg-formula" dspmath="mathimg" md5hash="d245c5bda2707cc6c23ca818ac751f9c"><svg:image xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="cp-19-1847-2023-ie00001.svg" width="33pt" height="14pt" src="cp-19-1847-2023-ie00001.png"/></svg:svg></span></span>. This correlation suggests that the control on these
proxies originates from internal cave processes such as prior carbonate
precipitation, which we infer to be related to precipitation amount. The
hydroclimate indicators furthermore suggest a shift towards overall drier
conditions after 46 ka, coincident with cooling in Antarctica and drier
conditions in the eastern part of South Africa corresponding to the summer
rainfall zone (SRZ).</p>
<p>Fluid inclusion-based temperature reconstructions show good agreement
between the oxygen isotope and microthermometry methods, and results from
the latter display little variation throughout the record, with
reconstructed temperatures close to the present-day cave temperature of 17.5 <span class="inline-formula"><sup>∘</sup></span>C. Overall, the BL3 speleothem record thus suggests relatively stable temperature from
48.3 to 45.2 ka, whereas precipitation was variable with marked drier
episodes on sub-millennial timescales.</p> |
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| ISSN: | 1814-9324 1814-9332 |