Amino acid racemization of planktonic foraminifera: pretreatment effects and temperature reconstructions
Amino acid racemization (AAR) is a geochronological method that uses the ratio of D- to L- configurations in optically active amino acids from carbonate-based fossils to determine the time elapsed since the death of an organism. In well-dated fossil samples, the extent of racemization can be used to...
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ftunivdelaware:oai:udspace.udel.edu:19716/24957 2023-06-11T04:16:09+02:00 Amino acid racemization of planktonic foraminifera: pretreatment effects and temperature reconstructions Watson, Emily 2019-08-07T16:03:32Z application/pdf http://udspace.udel.edu/handle/19716/24957 en eng University of Delaware 1137241006 http://udspace.udel.edu/handle/19716/24957 Thesis 2019 ftunivdelaware 2023-05-01T12:57:12Z Amino acid racemization (AAR) is a geochronological method that uses the ratio of D- to L- configurations in optically active amino acids from carbonate-based fossils to determine the time elapsed since the death of an organism. In well-dated fossil samples, the extent of racemization can be used to calculate post-depositional temperatures (also known as the effective diagenetic temperature). Calculated post-depositional temperatures of bracketed time intervals have uncertainties ranging from ±2 to 4°C with the dominant source of error in the D/L ratios (Kaufman 2003). Here, I aim to reduce these uncertainties using a bleach pretreatment that isolates the intra-crystalline fraction of amino acids in order to reduce the variability in foraminiferal D/L values to improve the precision of environmental paleotemperature estimates. I investigate the effect of this pretreatment method on the D/L ratios in three species of planktic foraminifera (Globorotalia tumida, Pulleniatina obliquiloculata, and Globorotalia truncatulinoides) from Holocene (~4-5 ka) deep sea sediments of similar environmental settings (Ocean Drilling Program Sites 1056, 1059, and 1062) and early Holocene to Pleistocene (~10.5-410 ka) sediments down-core (Ocean Drilling Program Site 1056 and KNR140 JPC-37). Results are reported for aspartic acid (Asp) and glutamic acid (Glu) because they are among the most abundant amino acids in foraminiferal protein and are the best resolved chromatographically. I analyzed 42 samples, each with an average of 9 replicates per sample and 5-10 individual tests per replicate, depending on the pretreatment method. Comparing D/L ratios from bleached versus unbleached samples indicates that bleaching only slightly reduces the variability in D/L values within the same sample (i.e. same species from the same core interval) by, on average, 1.1% and 3.0% for Asp and Glu, respectively. Furthermore, comparison of D/L ratios from the same species found at more than one site does not show statistical differences whether bleached ... Thesis Planktonic foraminifera The University of Delaware Library Institutional Repository |
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The University of Delaware Library Institutional Repository |
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English |
description |
Amino acid racemization (AAR) is a geochronological method that uses the ratio of D- to L- configurations in optically active amino acids from carbonate-based fossils to determine the time elapsed since the death of an organism. In well-dated fossil samples, the extent of racemization can be used to calculate post-depositional temperatures (also known as the effective diagenetic temperature). Calculated post-depositional temperatures of bracketed time intervals have uncertainties ranging from ±2 to 4°C with the dominant source of error in the D/L ratios (Kaufman 2003). Here, I aim to reduce these uncertainties using a bleach pretreatment that isolates the intra-crystalline fraction of amino acids in order to reduce the variability in foraminiferal D/L values to improve the precision of environmental paleotemperature estimates. I investigate the effect of this pretreatment method on the D/L ratios in three species of planktic foraminifera (Globorotalia tumida, Pulleniatina obliquiloculata, and Globorotalia truncatulinoides) from Holocene (~4-5 ka) deep sea sediments of similar environmental settings (Ocean Drilling Program Sites 1056, 1059, and 1062) and early Holocene to Pleistocene (~10.5-410 ka) sediments down-core (Ocean Drilling Program Site 1056 and KNR140 JPC-37). Results are reported for aspartic acid (Asp) and glutamic acid (Glu) because they are among the most abundant amino acids in foraminiferal protein and are the best resolved chromatographically. I analyzed 42 samples, each with an average of 9 replicates per sample and 5-10 individual tests per replicate, depending on the pretreatment method. Comparing D/L ratios from bleached versus unbleached samples indicates that bleaching only slightly reduces the variability in D/L values within the same sample (i.e. same species from the same core interval) by, on average, 1.1% and 3.0% for Asp and Glu, respectively. Furthermore, comparison of D/L ratios from the same species found at more than one site does not show statistical differences whether bleached ... |
format |
Thesis |
author |
Watson, Emily |
spellingShingle |
Watson, Emily Amino acid racemization of planktonic foraminifera: pretreatment effects and temperature reconstructions |
author_facet |
Watson, Emily |
author_sort |
Watson, Emily |
title |
Amino acid racemization of planktonic foraminifera: pretreatment effects and temperature reconstructions |
title_short |
Amino acid racemization of planktonic foraminifera: pretreatment effects and temperature reconstructions |
title_full |
Amino acid racemization of planktonic foraminifera: pretreatment effects and temperature reconstructions |
title_fullStr |
Amino acid racemization of planktonic foraminifera: pretreatment effects and temperature reconstructions |
title_full_unstemmed |
Amino acid racemization of planktonic foraminifera: pretreatment effects and temperature reconstructions |
title_sort |
amino acid racemization of planktonic foraminifera: pretreatment effects and temperature reconstructions |
publisher |
University of Delaware |
publishDate |
2019 |
url |
http://udspace.udel.edu/handle/19716/24957 |
genre |
Planktonic foraminifera |
genre_facet |
Planktonic foraminifera |
op_relation |
1137241006 http://udspace.udel.edu/handle/19716/24957 |
_version_ |
1768373612033605632 |