Atlantic 2MYr Foraminiferal Amino Acid Racemization Data Kvenvolden, K.A.; Peterson, E.; Wehmiller, J.F.; Hare, P.E. Kvenvolden, K.A. Peterson, E. Wehmiller, J.F. Hare, P.E. earth science/paleoclimate/others (V23-110>LATITUDE 17.63>LONGITUDE -45.87) (V12-122>LATITUDE 17>LONGITUDE -74.4) Ratios of D- to L-amino acids in acid hydrolysates from foraminifera of two deep-sea cores from the Caribbean Sea and Atlantic Ocean increase with depth and consequently with age over a span from 40,000 to 2,000,000 yr. The changing ratios do not seem to follow first-order reversible rate laws. Valine, leucine and glutamic acid apparently racemize (isoleucine epimerizes) at slower rates than do phenylalanine, alanine, aspartic acid and proline. The general relative order for rates of racemization of total (free and bound) amino acids may depend on the electron-withdrawing capacity of the R substituents of the amino acids and on the rates with which the amino acids are naturally hydrolyzed. In contrast to the total amino acids, the free amino acids in these samples are more extensively racemized, probably as a result of various catalytic and hydrolytic reactions. Previous related work based on ion-exchange chromatography has considered only ratios of alloisoleucine to isoleucine. With the gas chromatographic method used here, D/L ratios of all common asymmetric amino acids can be estimated. Measurement of the extent of racemization of amino acids in marine sediments seems to provide the basis for a geochronological tool covering the last few million years. STUDY NOTES: Measurement of D/L values for nine amino acids from mixed foraminfera samples from sediment cores from Atlantic and Caribbean cores. Wehmiller, J.F. , 1971. Diagenesis of amino acids in fossil calcerous organisms. PhD dissertation, Columbia University, Dept. of Geology, New York. 329 pp. NCDC-Paleoclimatology https://www.ncdc.noaa.gov/data-access/paleoclimatology-data - Bauer Bruce Investigator : Kvenvolden, K.A. Investigator : Peterson, E. Investigator : Wehmiller, J.F. Investigator : Hare, P.E. 2011-05-23 ONLINE Files online, ASCII https://www.ncdc.noaa.gov/paleo/study/11199 https://www1.ncdc.noaa.gov/pub/data/paleo/aar/kvenvolden1973forams/kvenvolden1973forams.txt https://www1.ncdc.noaa.gov/pub/data/paleo/aar/kvenvolden1973forams/kvenvolden1973forams.xls https://www1.ncdc.noaa.gov/pub/data/paleo/aar/kvenvolden1973forams/kvenvolden1973forams.txt https://www1.ncdc.noaa.gov/pub/data/paleo/aar/kvenvolden1973forams/kvenvolden1973forams.xls English https://www.ncdc.noaa.gov/paleo/study/11199 https://www1.ncdc.noaa.gov/pub/data/paleo/aar/kvenvolden1973forams/kvenvolden1973forams.txt https://www1.ncdc.noaa.gov/pub/data/paleo/aar/kvenvolden1973forams/kvenvolden1973forams.xls Kvenvolden, K.A., E. Peterson, J. Wehmiller, and P.E. Hare. 1973. Racemization of amino acids in marine sediments determined by gas chromatography. Geochimica et Cosmochimica Acta, Vol. 37, Issue 10, October 1973, pp. 2215-2225. doi:10.1016/0016-7037(73)90100-2 START YEAR: 2000000 cal yr BP * END YEAR: 40000 cal yr BP -74.4 17 -45.87 17.63