Geochronology of Holocene sediments on the western margin of South Africa

Herbert, Caren T.; Compton, John S.

doi:10.2113/gssajg.110.2-3.327

Cited by 38 publications

(51 citation statements)

References 33 publications

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“…Nevertheless, when compared with its SE counterpart, the South African margin, marked by intense upwelling and terrigenous input (Herbert and Compton 2007), the pattern observed in our study area shows important similarities, such as the presence of a starving surface on the outer shelf Wiltshire 2009, Compton et al 2010). In the Holocene mudbelt of the western margin of South Africa, Herbert and Compton (2007) estimated sedimentation rate values ranging from 25 to 240 cm.kyr -1 , whereas on the slope, the values varied from 4 to 22 cm.kyr -1 .…”

Section: Sedimentary Processessupporting

confidence: 50%

Radiocarbon geochronology of the sediments of the São Paulo Bight (southern Brazilian upper margin)

Mahiques

Sousa

Burone

et al. 2011

An. Acad. Bras. Ciênc.

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The aim of this work was to generate an inventory of the data on radiocarbon datings obtained from sediments of the São Paulo Bight (southern Brazilian upper margin) and to analyze the data in terms of Late Quaternary sedimentary processes and sedimentation rates. A total of 238 radiocarbon datings from materials collected using different sampling procedures was considered for this work. The sedimentation rates varied from less than 2 to 68 cm.kyr -1 . The highest sedimentation rate values were found in a low-energy (ría type) coastal system as well as in the upwelling zones of Santa Catarina and Cabo Frio. The lowest rates were found on the outer shelf and upper slopes. Our results confirm the strong dependency of the shelf currents, with an emphasis to the terrigenous input from the Río de La Plata outflow which is transported via the Brazilian Coastal Current, as well as of the coupled Brazil Current -Intermediate Western Boundary Current (BC-IWBC) dynamics on the sedimentary processes. At least three indicators of the paleo sea level were found at 12200 yr BP (conventional radiocarbon age) (103 meters below sea level -mbsl), 8300-8800 cal yr BP (13 mbsl) and 7700-8100 cal yr BP (6 mbsl).

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Section: Sedimentary Processessupporting

confidence: 50%

Radiocarbon geochronology of the sediments of the São Paulo Bight (southern Brazilian upper margin)

Mahiques

Sousa

Burone

et al. 2011

An. Acad. Bras. Ciênc.

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“…In contrast, an increasing flood occurrence in the banks of the Buffels River (Figs. 1 and 7j) (Benito et al, 2011) and in the Lower Orange River (Herbert and Compton, 2007, and references therein) as well as pulses of freshening events evident in the Lake Verlorenvlei record (Stager et al, 2012) (Figs. 1 and 7k) over the last 700-600 yr lend credence to our Nd and Sr isotope-based inference of increased sediment contribution from the local rivers.…”

Section: Climate Trend In Southwestern Africa During the "Little Ice mentioning

confidence: 87%

“…The mudbelt is a prominent Holocene sediment package that covers a narrow strip along the inner-shelf between the Kunene River in the northwest and St. Helena Bay in the southeast (Compton et al, 2009(Compton et al, , 2010Herbert and Compton, 2007;Meadows et al, 2002;Rogers and Rau, 2006).…”

Section: Regional Settingmentioning

confidence: 99%

“…1) that consists of Precambrian sedimentary rocks (> 2.5 billion years (Ga) old) and intrusions of 1 Ga granite and gneiss (Cowling et al, 1999). With a total catchment area of ∼ 65 200 km 2 and an arid/semi-arid climate, the overall sediment contribution of the local rivers to the mudbelt is estimated to be relatively small (a quantitative estimate is not available) as compared to that of the Orange River (Herbert and Compton, 2007;Meadows et al, 2002;Rogers and Rau, 2006). Notable sedimentary imprint of the ephemeral rivers is found in sediment sequences recovered from the immediate vicinity of local river mouths (Mabote, 1997;Rogers and Rau, 2006).…”

Section: Regional Settingmentioning

confidence: 99%

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Holocene climate variability in the winter rainfall zone of South Africa

Weldeab

Stuut

Schneider³

et al. 2013

Clim. Past

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Abstract. We established a multi-proxy time series comprising analyses of major elements in bulk sediments, Sr and Nd isotopes, grain size of terrigenous fraction, and δ 18 O and δ 13 C in tests of Neogloboquadrina pachyderma (sinistral) from a marine sediment sequence recovered off the Orange River. The records reveal coherent patterns of variability that reflect changes in wind strength, precipitation over the river catchments, and upwelling of cold and nutrient-rich coastal waters off western South Africa. The wettest episode of the Holocene in the winter rainfall zone (WRZ) of South Africa occurred during the "Little Ice Age" (700-100 cal years BP) most likely in response to a northward shift of the austral westerlies. Wet phases and strengthened coastal water upwellings are companied by a decrease of Agulhas water leakage into the South Atlantic and a reduced dust incursion over Antarctica, as indicated in previous studies. A continuous aridification trend in the WRZ and a weakening of the southern Benguela Upwelling System (BUS) between 9000 and 5500 cal years BP parallel with increase of dust deposition over Antarctica and an enhanced leakage of warm Agulhas water into the eastern South Atlantic. The temporal relationship between precipitation changes in the WRZ, the thermal state of the coastal surface water, and leakage of warm water in the South Atlantic, and variation of dust incursion over Antarctica suggests a causal link that most likely was related to latitudinal shifts of the Southern Hemisphere westerlies. Our results of the mid-Holocene time interval may serve as an analogue to a possible long-term consequence of the current and future southward shift of the westerlies. Furthermore, warming of the coastal surface water as a result of warm Agulhas water incursion into the southern BUS may affect coastal fog formation.

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“…This, coupled with the site setting in a back-flooding tributary mouth, the composition of the sediments through the excavated sequence, and the statistically similar OSL ages taken 700 mm apart in the west section imply that PL1 is a slackwater deposit, most likely reflecting three or more large flood events in the Doring River around the start of MIS 3. Dated slackwater deposits are known from the Holocene and the Last Glacial Maximum in the Orange River and further north in Namibia (Heine and Heine, 2002;Heine and Volkel, 2011;Herbert and Compton, 2007), but have previously not been documented from MIS 3. Further OSL work along the river may allow the temporal range, magnitude and periodicity of these events to be identified.…”

Section: Discussionmentioning

confidence: 99%

Putslaagte 1 (PL1), the Doring River, and the later Middle Stone Age in southern Africa's Winter Rainfall Zone

Mackay

Sumner

Jacobs

et al. 2014

Quaternary International

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Existing data suggest weak human occupation of southern Africa's Winter Rainfall Zone (WRZ) during later Marine Isotope Stage (MIS) 3, the causes of which are unknown. Here we report briefly on the results of recent surveys of alluvial terrace sites of the Doring River in the WRZ, which document occupation over a broad expanse of the later Middle Stone Age (MSA) and Pleistocene Later Stone Age. We then report on test excavations at one terrace site, denoted Putslaagte site 1 (PL1), describe in detail the assemblage of flaked stone artefacts produced from that excavation, and present two OSL ages obtained from 0.8 m to 1.5 m below surface. The results suggest that a) artefact accumulations at PL1 are dense, b) the technological systems documented are characteristically MSA but differ in form from the range of systems known from other excavated sites in the region, and c) that the assemblages accumulated in MIS 3. Taken together with the survey data the results introduce new variation into the later MSA in southern Africa, and imply reorganisation of land use in the WRZ in late MIS 3 rather than abandonment. We suggest that a research emphasis on rock shelter deposits may have produced misleading depictions of regional occupation. AbstractExisting data suggest weak human occupation of southern Africa's Winter Rainfall Zone (WRZ) during later Marine Isotope Stage (MIS) 3, the causes of which are unknown. Here we report briefly on the results of recent surveys of alluvial terrace sites of the Doring River in the WRZ, which document occupation over a broad expanse of the later Middle Stone Age (MSA) and Pleistocene Later Stone Age. We then report on test excavations at one terrace site, denoted Putslaagte site 1 (PL1), describe in detail the assemblage of flaked stone artefacts produced from that excavation, and present two OSL ages obtained from 0.8 m and 1.5 m below surface. The results suggest that a) artefact accumulations at PL1 are extremely dense, b) the technological systems documented are characteristically MSA but differ in form from the range of systems known from other excavated sites in the region, and c) that the assemblages accumulated in MIS 3. Taken together with the survey data the results introduce new variation into the later MSA in southern Africa, and imply reorganisation of land use in the WRZ in late MIS 3 rather than abandonment. We suggest that a research emphasis on rock shelter deposits may have produced misleading depictions of regional occupation.

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Geochronology of Holocene sediments on the western margin of South Africa

Cited by 38 publications

References 33 publications

Radiocarbon geochronology of the sediments of the São Paulo Bight (southern Brazilian upper margin)

Radiocarbon geochronology of the sediments of the São Paulo Bight (southern Brazilian upper margin)

Holocene climate variability in the winter rainfall zone of South Africa

Putslaagte 1 (PL1), the Doring River, and the later Middle Stone Age in southern Africa's Winter Rainfall Zone

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