Peruvian Speleothem Record of Climate and Hydrologic Variability from 167,000 yrs B.P. to 135,000 yrs B.P.
Peruvian speleothems have been shown to be excellent recorders of paleoclimate by tracking changes in rainfall amount through oxygen isotopes in calcite. Measured changes in rainfall amount have been attributed to changes in the intensity of the South American Seasonal Monsoon (SASM). High insolatio...
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ftunioncollege:oai:digitalworks.union.edu:theses-3634 2023-05-15T16:41:34+02:00 Peruvian Speleothem Record of Climate and Hydrologic Variability from 167,000 yrs B.P. to 135,000 yrs B.P. Plummer, Ian 2022-06-01T07:00:00Z application/pdf https://digitalworks.union.edu/theses/2587 https://digitalworks.union.edu/cgi/viewcontent.cgi?article=3634&context=theses unknown Union | Digital Works https://digitalworks.union.edu/theses/2587 https://digitalworks.union.edu/cgi/viewcontent.cgi?article=3634&context=theses Honors Theses paleoclimate peru speleothem hydrology monsoon MIS 6 caves hydroclimate andes tropics Geology Glaciology Other Earth Sciences text 2022 ftunioncollege 2022-09-10T17:25:54Z Peruvian speleothems have been shown to be excellent recorders of paleoclimate by tracking changes in rainfall amount through oxygen isotopes in calcite. Measured changes in rainfall amount have been attributed to changes in the intensity of the South American Seasonal Monsoon (SASM). High insolation in the Southern Hemisphere and low insolation in the Northern Hemisphere is believed to increase the meridional SST gradient, leading to a southerly migration of the mean position of the Inter-Tropical Convergence Zone (ITCZ) and strengthening of the SASM intensity. Conversely, a decrease in Southern Hemisphere insolation and an increase in Northern Hemisphere insolation is believed to have led the ITCZ to a more northerly mean position and weakening of SASM intensity. I present a record from speleothem 19-11, which grew in Pacupahuain Cave between 167,068 yrs B.P. and 135,165 yrs B.P., also known as the penultimate glacial period or Marine Isotope Stage 6 (MIS 6). The δ18O record from 19-11 shows exceptional agreement with overlapping speleothem records from nearby Huagapo Cave (HC). All of these records are anti-phased with 11°S January insolation, supporting the idea that shifts in the mean position of the ITCZ modulate SASM intensity. From 165 ka to 150 ka an increase in δ18O occurs contemporaneously with a decrease in 11°S Jan insolation. This period of time reflects a broad decrease in SASM intensity, a hypothesis corroborated by decreased sediment input into regional lake records. δ18O values are lower at the beginning and end of the 19-11 record, coinciding with 11°S Jan insolation highs. Within long-term insolation driven changes in δ18O, the 19-11 record has rapid oscillations that are also seen in the HC records. Previous researchers have attributed these rapid fluctuations to high-latitude Northern Hemisphere forcing. Increased temperature in the Northern Atlantic and ice sheet melt coincides with apparent weakening of the SASM. This relationship is explained by a weakening of SST gradient and northern ... Text Ice Sheet Union College: Digital Works |
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Union College: Digital Works |
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ftunioncollege |
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unknown |
topic |
paleoclimate peru speleothem hydrology monsoon MIS 6 caves hydroclimate andes tropics Geology Glaciology Other Earth Sciences |
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paleoclimate peru speleothem hydrology monsoon MIS 6 caves hydroclimate andes tropics Geology Glaciology Other Earth Sciences Plummer, Ian Peruvian Speleothem Record of Climate and Hydrologic Variability from 167,000 yrs B.P. to 135,000 yrs B.P. |
topic_facet |
paleoclimate peru speleothem hydrology monsoon MIS 6 caves hydroclimate andes tropics Geology Glaciology Other Earth Sciences |
description |
Peruvian speleothems have been shown to be excellent recorders of paleoclimate by tracking changes in rainfall amount through oxygen isotopes in calcite. Measured changes in rainfall amount have been attributed to changes in the intensity of the South American Seasonal Monsoon (SASM). High insolation in the Southern Hemisphere and low insolation in the Northern Hemisphere is believed to increase the meridional SST gradient, leading to a southerly migration of the mean position of the Inter-Tropical Convergence Zone (ITCZ) and strengthening of the SASM intensity. Conversely, a decrease in Southern Hemisphere insolation and an increase in Northern Hemisphere insolation is believed to have led the ITCZ to a more northerly mean position and weakening of SASM intensity. I present a record from speleothem 19-11, which grew in Pacupahuain Cave between 167,068 yrs B.P. and 135,165 yrs B.P., also known as the penultimate glacial period or Marine Isotope Stage 6 (MIS 6). The δ18O record from 19-11 shows exceptional agreement with overlapping speleothem records from nearby Huagapo Cave (HC). All of these records are anti-phased with 11°S January insolation, supporting the idea that shifts in the mean position of the ITCZ modulate SASM intensity. From 165 ka to 150 ka an increase in δ18O occurs contemporaneously with a decrease in 11°S Jan insolation. This period of time reflects a broad decrease in SASM intensity, a hypothesis corroborated by decreased sediment input into regional lake records. δ18O values are lower at the beginning and end of the 19-11 record, coinciding with 11°S Jan insolation highs. Within long-term insolation driven changes in δ18O, the 19-11 record has rapid oscillations that are also seen in the HC records. Previous researchers have attributed these rapid fluctuations to high-latitude Northern Hemisphere forcing. Increased temperature in the Northern Atlantic and ice sheet melt coincides with apparent weakening of the SASM. This relationship is explained by a weakening of SST gradient and northern ... |
format |
Text |
author |
Plummer, Ian |
author_facet |
Plummer, Ian |
author_sort |
Plummer, Ian |
title |
Peruvian Speleothem Record of Climate and Hydrologic Variability from 167,000 yrs B.P. to 135,000 yrs B.P. |
title_short |
Peruvian Speleothem Record of Climate and Hydrologic Variability from 167,000 yrs B.P. to 135,000 yrs B.P. |
title_full |
Peruvian Speleothem Record of Climate and Hydrologic Variability from 167,000 yrs B.P. to 135,000 yrs B.P. |
title_fullStr |
Peruvian Speleothem Record of Climate and Hydrologic Variability from 167,000 yrs B.P. to 135,000 yrs B.P. |
title_full_unstemmed |
Peruvian Speleothem Record of Climate and Hydrologic Variability from 167,000 yrs B.P. to 135,000 yrs B.P. |
title_sort |
peruvian speleothem record of climate and hydrologic variability from 167,000 yrs b.p. to 135,000 yrs b.p. |
publisher |
Union | Digital Works |
publishDate |
2022 |
url |
https://digitalworks.union.edu/theses/2587 https://digitalworks.union.edu/cgi/viewcontent.cgi?article=3634&context=theses |
genre |
Ice Sheet |
genre_facet |
Ice Sheet |
op_source |
Honors Theses |
op_relation |
https://digitalworks.union.edu/theses/2587 https://digitalworks.union.edu/cgi/viewcontent.cgi?article=3634&context=theses |
_version_ |
1766032004747362304 |