Stable carbon and oxygen isotopic evidence for late Pleistocene to middle Holocene climatic fluctuations in the interior of southern Africa

Abstract

2002. Stable carbon and oxygen isotopic evidence for late Pleistocene to middle Holocene climatic fluctuations in the interior of southern Africa.ABSTRACT: Stable carbon and oxygen isotope analyses of ungulate grazers from four archaeological sites located in different environs within the Caledon River Valley have provided a relatively well-dated proxy palaeoenvironmental and palaeoclimatic sequence for the period between 16 000 and 6000 calendar (cal.) yr BP. Within the overall trend towards hot mid-Holocene temperatures and a summer rainfall pattern, stable carbon isotope results show that there were three periods when growth season temperatures were cool enough for C 3 grasses to be present: 16 000-14 000; 10 200-9600, and 8400-8000 cal. yr BP. Similar trends were recorded in stable oxygen isotope values, reflecting shifts in either temperature or available moisture. Although having a similar pattern to that of the lower altitude site, sites situated in foothills and montane portions of the valley consistently maintained lower temperatures until the mid-Holocene altithermal. At this time growth season temperatures warmed sufficiently for a 100% C 4 grassland to expand in altitude from the warmer low lying localities. In relation to present understanding of synoptic and global climatic patterning, these findings suggest that the early to middle Holocene transition was not a gradual warming trend, but rather it was marked by a series of climatic fluctuations. Of particular note is the possible global, rather than regional, occurrence of the 8200 cal. yr BP 'event'.

Sources of carbon isotope variation in kangaroo bone collagen and tooth enamel

“…This approach has provided strong evidence of a global expansion of C 4 grasses since the Miocene Passey et al, 2002), and fluctuations in C 4 relative abundance since the Pleistocene (Smith et al, 2002;Miller et al, 2005). C 4 relative abundance itself has been used as a proxy for a number of environmental variables, including atmospheric CO 2 concentration , temperature (Smith et al, 2002), and summer rainfall (Connin et al, 1998).…”

multi-disciplinary review of late Quaternary palaeoclimates and environments for Lesotho

“…43,52 Consequently, there have been continued calls, and recent efforts made, to extract palaeobotanical climate proxiesincluding charcoal, faunal remains, phytoliths and stable isotopes -from material recovered at archaeological excavations in the region. 4,7,9,19,48,59 Palaeoenvironmental reconstructions Detailed continuous palaeoenvironmental records from Lesotho are limited. 3,5,7 For example, the only pollen reconstruction for the eastern Lesotho highlands 60 was sampled at poor resolution and lacks chronology, and no information on site location is provided.…”

“…4,9,19,53,59 Holocene charcoal assemblages were analysed from three shelters (Tloutle, Ha Makotoko and Ntloana Tsoana) along a tributary of the Caledon River in western Lesotho (Figure 1). 19,66 Considerable differences in species composition were noted between Tloutle, which is closer to the river, and Ha Makotoko and Ntloana Tsoana throughout the periods of occupation; these findings highlight the influence of microclimates within small geographic areas in Lesotho 19 .…”

“…4,59 The isotopic values for herbivore grazers reflect the proportion of C 3 :C 4 vegetation consumed, from which the vegetation balance at the site can be inferred 59 . Evidence for the three Caledon River sites in Lesotho indicate a progressive warming from 16 000 to 6000 cal yr BP, marked by considerable fluctuations.…”

“…Evidence for the three Caledon River sites in Lesotho indicate a progressive warming from 16 000 to 6000 cal yr BP, marked by considerable fluctuations. 59 The fluctuations notably include periods that were sufficiently cool to encourage the growth of C 3 plants during the periods 16 000-14 000 cal yr BP, 10 200-9600 cal yr BP and 8400-8000 cal yr BP. 59 A more recent study using stable carbon isotopes provides further environmental proxy data for Ntloana Tsoana and Tloutle for the period spanning the Pleistocene-Holocene transition.…”