noaa-other-10290 South Africa Deglacial Hyrax Midden Stable Isotope Data Chase, B.M.; Quick, L.J.; Meadows, M.E.; Scott, L.; Thomas, D.S.G.; Reimer, P.J. South Africa Deglacial Hyrax Midden Stable Isotope Data 2011-01-27 NCDC-Paleoclimatology ONLINE Files Pending https://www.ncdc.noaa.gov/paleo/study/10290 Investigator B.M. Chase Investigator L.J. Quick Investigator M.E. Meadows Investigator L. Scott Investigator D.S.G. Thomas Investigator P.J. Reimer earth science paleoclimate others geoscientificInformation Younger Dryas 19386 cal yr BP 7261 cal yr BP Complete -32.446 -32.446 19.221 19.221 Continent Africa Southern Africa South Africa De Rif>LATITUDE -32.446>LONGITUDE 19.221 None Please cite original publication, online resource, dataset and publication DOIs (where available), and date accessed when using downloaded data. If there is no publication information, please cite investigator, title, online resource, and date accessed. The appearance of external links associated with a dataset does not constitute endorsement by the Department of Commerce/National Oceanic and Atmospheric Administration of external Web sites or the information, products or services contained therein. For other than authorized activities, the Department of Commerce/NOAA does not exercise any editorial control over the information you may find at these locations. These links are provided consistent with the stated purpose of this Department of Commerce/NOAA Web site. English DOC/NOAA/NESDIS/NCEI National Centers for Environmental Information, NESDIS, NOAA, U.S. Department of Commerce https://www.ncdc.noaa.gov/data-access/paleoclimatology-data DATA Center Contact Bruce Bauer bruce.a.bauer@noaa.gov paleo@noaa.gov 303-497-6280 303-497-6513

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Boulder CO 80305-3328 USA online ASCII Chase, B.M., L.J. Quick, M.E. Meadows, L. Scott, D.S.G. Thomas, and P.J. Reimer. 2011. Late-glacial interhemispheric climate dynamics revealed in South African hyrax middens. Geology, Vol. 39, No. 1, pp. 19-22, January 2011. doi:10.1130/G31129.1

Our ability to identify the timing and extent of past major climate fluctuations is central to understanding changes in the global climate system. Of the events that have occurred in recent geological time, the Younger Dryas (YD, 13-11.5 ka), an abrupt return to near-glacial conditions during the last glacial-interglacial transition (ca. 18-11.5 ka), is one of the most widely reported. While this event is apparent throughout the Northern Hemisphere (Peteet, 1995), evidence for its occurrence in the Southern Hemisphere remains equivocal due to a lack of well-dated terrestrial records. Here we report high-resolution stable carbon and nitrogen isotope records obtained from a rock hyrax midden, revealing the first unequivocal terrestrial manifestation of the YD from the southern African subtropics. These results provide key evidence for the relative influence of the YD, and suggest that a subtropical-temperate transition zone existed along the oceanic Subtropical Front (~41°S) across the Southern Hemisphere, with the Northern Hemisphere exerting a strong influence on all but the higher latitudes of the Southern Hemisphere after the Heinrich Stadial 1 (15 ka). STUDY NOTES: Here we present stable carbon and nitrogen isotope data obtained from a rock hyrax (Procavia capensis) midden recovered from the Cederberg Mountains of South Africa's Western Cape (32.446°S, 19.221°E). Located in the core of southern Africa's winter rainfall zone (sensu Chase and Meadows (2007)), the site presently receives c. 380 mm yr-1 of rainfall with >80% falling between April and October. This marked seasonality is a product of the annual expansions and migrations of westerly storm tracks and associated frontal systems. Each winter these systems bring rain to southwestern Africa and each summer, as they contract poleward, their influence is replaced by the southward displacement of the South Atlantic Anticyclone and the development of coastal upwelling cells. The behaviour and influence of these systems on terrestrial environments over centennial to multi-millennial timescales, however, remains largely unresolved. Accelerator mass spectrometry radiocarbon analyses of 10 samples from a 400 mm section of the De Rif midden indicate that it was deposited between ca. 19,500 and 7300 cal yr B.P., spanning the entire Last Glacial-Interglacial Transition (LGIT). Further, the distribution of ages as a function of depth shows that accumulation throughout this period was broadly continuous, with no hiatuses indicated. Upper (0-70 mm) and lower (235-400 mm) sections are composed primarily of urine and accumulated at a rate of ~20–30 um yr-1. Separating these sections is a 165-mm-thick layer that contains a greater admixture of fecal pellets, which increased the rate of deposition to ~94 um yr-1. Samples for stable isotope analysis were drilled by hand with a 1-mm-diameter drill bit with an average sample interval of 1.5 mm. The d15N values vary from 5.3‰ to -2.3‰. Among herbivores, such 15N abundance in animal tissues is influenced by climate, diet, and/or physiology (Ambrose and DeNiro, 1986; Heaton et al., 1986). While many studies have focused on the possible effects of animal metabolism on the signal (Ambrose and DeNiro, 1986), studies of d15N in plants across aridity gradients indicate clear correlations between enriched d15N and decreased rainfall (Murphy and Bowman, 2006; Schwarcz et al., 1999), suggesting that metabolism per se may have negligible or relatively minor influence on the signal. In particular, spatially extensive studies of d15N in both grass and kangaroo bone from across Australia reveal a strong, consistent relationship between plant and bone d15N values, suggesting that water availability, through its influence on the isotopic signature of consumed vegetation, is the primary control on animal d15N, with metabolism having no clear effect (Murphy and Bowman, 2006). These findings are supported by stable isotope records obtained from hyrax middens in Namibia, which show strong similarities between variations in d15N and a range of paleoenvironmental proxies reflecting changes in precipitation over multimillennial time scales (Chase et al., 2009). The d13C values from the midden vary between -28.3‰ and -26.9‰. As a reflection of hyrax diet, these values indicate that the site has hosted a predominantly to purely C3 vegetation throughout the recorded period. This ecosystem stability over time provides a unique opportunity for variations in d13C to be used as a proxy for climate rather than vegetation. Although variations in d13C in middens are often interpreted in terms of changing proportions of C3 versus C4 plants in the landscape (Scott and Vogel, 2000), in ecosystems supporting only C3 plants, variations in d13C are primarily a function of leaf-level changes in water-use efficiency (Ehleringer and Cooper, 1988). Thus, the d13C variations in the De Rif hyrax midden are interpreted as primarily reflecting changes in effective precipitation. This interpretation is supported by the strong similarities that are evident between the d13C and d15N records (and argues against a significant influence of long-term changes in atmospheric CO2; Arens et al., 2000), providing mutual validation that climate is the primary determinant of the observed signals.

GET DATA https://www1.ncdc.noaa.gov/pub/data/paleo/midden/africa/de-rif2011iso.txt GET DATA https://www1.ncdc.noaa.gov/pub/data/paleo/midden/africa/de-rif2011iso.xls USA/NOAA DIF Version 9.8.4 2018-12-11 2018-12-11