Laguna La Gaiba, Bolivia 40 KYr Leaf Wax Carbon and Hydrogen Isotope Data Fornace, K.; Whitney, B.S.; Galy, V.V.; Hughen, K.A.; Mayle, F.E. Fornace, K. Whitney, B.S. Galy, V.V. Hughen, K.A. Mayle, F.E. Monsoon earth science/paleoclimate/paleolimnology (delta 13C,C31 n-alkane,one standard deviation,per mil VPDB,null,paleolimnology,null,gas chromatography|isotope ratio mass spectrometry,N,null) earth science/paleoclimate/paleolimnology (depth,null,null,centimeter,null,paleolimnology,null,null,N,null) earth science/paleoclimate/paleolimnology (delta 13C,C29 n-alkane,null,per mil VPDB,null,paleolimnology,null,gas chromatography|isotope ratio mass spectrometry,N,null) earth science/paleoclimate/paleolimnology (delta 2H,C33 n-alkane,null,per mil VSMOW,null,paleolimnology,corrected,gas chromatography|isotope ratio mass spectrometry,N,corrected for ice volume effects on mean ocean dD) earth science/paleoclimate/paleolimnology (sample identification,null,null,null,null,paleolimnology,null,null,C,null) earth science/paleoclimate/paleolimnology (delta 2H,C29 n-alkane,null,per mil VSMOW,null,paleolimnology,corrected,gas chromatography|isotope ratio mass spectrometry,N,corrected for ice volume effects on mean ocean dD) earth science/paleoclimate/paleolimnology (delta 13C,C31 n-alkane,null,per mil VPDB,null,paleolimnology,null,gas chromatography|isotope ratio mass spectrometry,N,null) earth science/paleoclimate/paleolimnology (delta 13C,C33 n-alkane,one standard deviation,per mil VPDB,null,paleolimnology,null,gas chromatography|isotope ratio mass spectrometry,N,null) earth science/paleoclimate/paleolimnology (delta 2H,C31 n-alkane,one standard deviation,per mil VSMOW,null,paleolimnology,corrected,gas chromatography|isotope ratio mass spectrometry,N,corrected for ice volume effects on mean ocean dD) earth science/paleoclimate/paleolimnology (delta 13C,C29 n-alkane,one standard deviation,per mil VPDB,null,paleolimnology,null,gas chromatography|isotope ratio mass spectrometry,N,null) earth science/paleoclimate/paleolimnology (delta 13C,C27 n-alkane,null,per mil VPDB,null,paleolimnology,null,gas chromatography|isotope ratio mass spectrometry,N,null) earth science/paleoclimate/paleolimnology (delta 13C,C27 n-alkane,one standard deviation,per mil VPDB,null,paleolimnology,null,gas chromatography|isotope ratio mass spectrometry,N,null) earth science/paleoclimate/paleolimnology (delta 2H,C29 n-alkane,one standard deviation,per mil VSMOW,null,paleolimnology,corrected,gas chromatography|isotope ratio mass spectrometry,N,corrected for ice volume effects on mean ocean dD) earth science/paleoclimate/paleolimnology (delta 2H,C31 n-alkane,null,per mil VSMOW,null,paleolimnology,corrected,gas chromatography|isotope ratio mass spectrometry,N,corrected for ice volume effects on mean ocean dD) earth science/paleoclimate/paleolimnology (delta 2H,C33 n-alkane,one standard deviation,per mil VSMOW,null,paleolimnology,corrected,gas chromatography|isotope ratio mass spectrometry,N,corrected for ice volume effects on mean ocean dD) earth science/paleoclimate/paleolimnology (age,null,null,calendar year before present,null,paleolimnology,null,null,N,null) earth science/paleoclimate/paleolimnology (delta 13C,C33 n-alkane,null,per mil VPDB,null,paleolimnology,null,gas chromatography|isotope ratio mass spectrometry,N,null) earth science/paleoclimate/paleolimnology earth science/paleoclimate/paleolimnology (Laguna La Gaiba>LATITUDE -17.77>LONGITUDE -57.72) Stable isotope analysis of leaf waxes in a sediment core from Laguna La Gaiba, a shallow lake located at the Bolivian margin of the Pantanal wetlands, provides new perspective on vegetation and climate change in the lowland interior tropics of South America over the past 40,000 years. The carbon isotopic compositions (d13C) of long-chain n-alkanes reveal large shifts between C3- and C4-dominated vegetation communities since the last glacial period, consistent with landscape reconstructions generated with pollen data from the same sediment core. Leaf wax d13C values during the last glacial period reflect an open landscape composed of C4 grasses and C3 herbs from 41-20 ka. A peak in C4 abundance during the Last Glacial Maximum (LGM, ~21 ka) suggests drier or more seasonal conditions relative to the earlier glacial period, while the development of a C3-dominated forest community after 20 ka points to increased humidity during the last deglaciation. Within the Holocene, large changes in the abundance of C4 vegetation indicate a transition from drier or more seasonal conditions during the early/mid-Holocene to wetter conditions in the late Holocene coincident with increasing austral summer insolation. Strong negative correlations between leaf wax d13C and image values over the entire record indicate that the majority of variability in leaf wax image at this site can be explained by variability in the magnitude of biosynthetic fractionation by different vegetation types rather than changes in meteoric water image signatures. However, positive image deviations from the observed d13C-image trends are consistent with more enriched source water and drier or more seasonal conditions during the early/mid-Holocene and LGM. Overall, our record adds to evidence of varying influence of glacial boundary conditions and orbital forcing on South American Summer Monsoon precipitation in different regions of the South American tropics. Moreover, the relationships between leaf wax stable isotopes and pollen data observed at this site underscore the complementary nature of pollen and leaf wax d13C data for reconstructing past vegetation changes and the potentially large effects of such changes on leaf wax image signatures. STUDY NOTES: Leaf wax (C27-C33 n-alkane) carbon and hydrogen isotope data from Laguna La Gaiba sediments NCDC-Paleoclimatology https://www.ncdc.noaa.gov/data-access/paleoclimatology-data - Bauer Bruce Investigator : Fornace, K. Investigator : Whitney, B.S. Investigator : Galy, V.V. Investigator : Hughen, K.A. Investigator : Mayle, F.E. 2016-03-04 ONLINE Files online, ASCII https://www.ncdc.noaa.gov/paleo/study/19848 https://www1.ncdc.noaa.gov/pub/data/paleo/paleolimnology/southamerica/bolivia/gaiba2016iso.txt https://www1.ncdc.noaa.gov/pub/data/paleo/paleolimnology/southamerica/bolivia/gaiba2016iso.txt English https://www.ncdc.noaa.gov/paleo/study/19848 https://www1.ncdc.noaa.gov/pub/data/paleo/paleolimnology/southamerica/bolivia/gaiba2016iso.txt Kyrstin L. Fornace, Bronwen S. Whitney, Valier Galy, Konrad A. Hughen, Francis E. Mayle2016Late Quaternary environmental change in the interior South American tropics: new insight from leaf wax stable isotopesEarth and Planetary Science Letters43875-7810.1016/j.epsl.2016.01.007http://www.sciencedirect.com/science/article/pii/S0012821X16000145 START YEAR: 41100 cal yr BP * END YEAR: 0 cal yr BP -57.72 -17.77 -57.72 -17.77