In search of sediment deposits from the Limpopo (Delagoa Bight, southern Africa): Deciphering the catchment provenance of coastal sediments

Schüürman, Jan; Hahn, Annette; Zabel, Matthias

doi:10.1016/j.sedgeo.2018.11.012

Cited by 20 publications

(9 citation statements)

References 26 publications

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“…As they pass the Delagoa Bight, these eddies, together with the Agulhas Current itself, drive the Delagoa Bight eddy; a topographically constrained cyclonic lee eddy at the coring location (Lutjeharms and Da Silva, 1988;Quartly and Srokosz, 2004). Although the coring site is located just west of the mouth of the major Limpopo river system, Schüürman et al, (2019) show that the inorganic material at our site most likely originates from three minor rivers, Incomati, Matola, and Lusutfu, that flow into the Indian Ocean further to the southwest. This is attributed to the eastward deflection of the Limpopo sediments by the Delagoa Bight eddy.…”

Section: Regional Settingmentioning

confidence: 99%

Glacial to interglacial climate variability in the southeastern African subtropics (25–20° S)

Hahn¹,

Schefuß²,

Groeneveld³

et al. 2020

Preprint

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Abstract. We present a continuous and well-resolved record of climatic variability for the past 100,000 yrs from a marine sediment core taken in Delagoa Bight, off southeastern Africa. In addition to providing a sea surface temperature reconstruction for the past ca. 100,000 yrs, this record also allows a high-resolution continental climatic reconstruction. Climate sensitive organic proxies, like the distribution and isotopic composition of plant-wax lipids as well as elemental indicators for fluvial input and weathering type provide information on climatic changes in the adjacent catchment areas (Incomati, Matola, and Lusutfu rivers). At the transition between glacials and interglacials, shifts in vegetation correlate with changes in sea surface temperature in the Agulhas current. The local hydrology, however, does not follow these orbital-paced shifts. Instead, precipitation patterns follow millennial scale variations with different forcing mechanisms in glacial versus interglacial climatic states. During glacials, southward displacement of the Intertropical Convergence Zone facilitates a transmission of northern hemispheric signals (e.g. Heinrich events) to the southern hemispheric subtropics. Furthermore, the southern hemispheric westerlies become a more direct source of precipitation as they shift northward over the study site, especially during Antarctic cold phases. During interglacials, the observed short-term hydrological variability is also a function of Antarctic climate variability, however, it is driven by the indirect influence of the southern hemispheric westerlies and the associated South African high-pressure cell blocking the South Indian Ocean Convergence Zone related precipitation. As a consequence of the interplay of these effects, small scale climatic zones exist. We propose a conceptual model describing latitudinal shifts of these zones along the southeastern African coast as tropical and temperate climate systems shift over glacial and interglacial cycles. The proposed model explains some of the apparent contradictions between several paleoclimate records in the region.

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Section: Regional Settingmentioning

confidence: 99%

Glacial to interglacial climate variability in the southeastern African subtropics (25–20° S)

Hahn¹,

Schefuß²,

Groeneveld³

et al. 2020

Preprint

Self Cite

View full text Add to dashboard Cite

show abstract

“…As they pass the Delagoa Bight, these eddies, together with the Agulhas Current itself, drive the Delagoa Bight eddy, a topographically constrained cyclonic lee eddy at the coring location (Lutjeharms and Da Silva, 1988;Quartly and Srokosz, 2004). Although the coring site is located just west of the mouth of the major Limpopo River system, Schüürman et al (2019) show that the inorganic material at our site most likely originates from three minor rivers -Incomati, Matola and Lusutfu -that flow into the Indian Ocean further to the southwest. This is attributed to the eastward deflection of the Limpopo sediments by the Delagoa Bight eddy.…”

Section: Regional Settingmentioning

confidence: 77%

“…This is attributed to the eastward deflection of the Limpopo sediments by the Delagoa Bight eddy. The eddy appears to have been stable and strong enough to effectively constrain the drift of the Limpopo sediments eastwards over the Late Pleistocene and Holocene (Schüürman et al, 2019). The three rivers -Incomati (also known as Komati), Matola (also known as Umbeluzi) and Lusutfu (also known as Maputo) -have catchment areas of ca.…”

Section: Regional Settingmentioning

confidence: 99%

Glacial to interglacial climate variability in the southeastern African subtropics (25–20° S)

et al. 2021

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Abstract. We present a continuous and well-resolved record of climatic variability for the past 100 000 years from a marine sediment core taken in Delagoa Bight, off southeastern Africa. In addition to providing a sea surface temperature reconstruction for the past ca. 100 000 years, this record also allows a high-resolution continental climatic reconstruction. Climate sensitive organic proxies, like the distribution and isotopic composition of plant-wax lipids as well as elemental indicators of fluvial input and weathering type provide information on climatic changes in the adjacent catchment areas (Incomati, Matola and Lusutfu rivers). At the transition between glacials and interglacials, shifts in vegetation correlate with changes in sea surface temperature in the Agulhas Current. The local hydrology, however, does not follow these orbitally paced shifts. Instead, precipitation patterns follow millennial-scale variations with different forcing mechanisms in glacial vs. interglacial climatic states. During glacials, southward displacement of the Intertropical Convergence Zone facilitates a transmission of northern hemispheric signals (e.g., Heinrich events) to the southern hemispheric subtropics. Furthermore, the southern hemispheric westerlies become a more direct source of precipitation as they shift northward over the study site, especially during Antarctic cold phases. During interglacials, the observed short-term hydrological variability is also a function of Antarctic climate variability; however, it is driven by the indirect influence of the southern hemispheric westerlies and the associated South African high-pressure cell blocking the South Indian Ocean Convergence Zone related precipitation. As a consequence of the interplay of these effects, small-scale climatic zones exist. We propose a conceptual model describing latitudinal shifts of these zones along the southeastern African coast as tropical and temperate climate systems shift over glacial and interglacial cycles. The proposed model explains some of the apparent contradictions between several paleoclimate records in the region.

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“…Limpopo River sediment is thought to form the Limpopo Cone (Martin 1981); however, a large fraction of the sediment is being dispersed in the ocean (Walsh and Nittrouer 2009). Recently, it has been shown that a large part of Limpopo sediment is transported eastwards on the shelf, attributed to the Delagoa Bight eddy (Schüürman et al 2019).…”

Section: Regional Settingmentioning

confidence: 99%

“…The southern Mozambique continental shelf has not been a focus of geoscientific research in the last decades, with the exception of studies on coastal development south of Maputo (Cooper and Pilkey 2002;Armitage et al 2006;Green et al 2015) and sediment provenance in the Delagoa Bight (Schüürman et al 2019). However, the neighboring KwaZulu-Natal shelf in South Africa has been investigated by a number of studies.…”

Section: Regional Settingmentioning

confidence: 99%

Geological development of the Limpopo Shelf (southern Mozambique) during the last sealevel cycle

2020

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Paleo-shorelines on continental shelves give insights into the complex development of coastlines during sealevel cycles. This study investigates the geologic development of the Limpopo Shelf during the last sealevel cycle using multichannel seismic and acoustic datasets acquired on the shelf in front of the Limpopo River mouth. A detailed investigation of seismic facies, shelf bathymetry, and a correlation to sea level revealed the presence of numerous submerged shorelines on the shelf. These shorelines are characterized by distinct topographic ridges and are interpreted as coastal dune ridges that formed in periods of intermittent sealevel still-/slowstand during transgression. The shorelines are preserved due to periods of rapid sealevel rise (melt water pulses) that led to the overstepping of the dune ridges as well as due to early cementation of accumulated sediments that increased the erosive resistance of the ridges. The high along-shelf variability of the submerged dune ridges is interpreted as a result of pre-existing topography affecting shoreline positions during transgression. The pre-existing topography is controlled by the underlying sedimentary deposits that are linked to varying fluvial sediment input at different points on the shelf. The numerous prominent submerged dune ridges form barriers for the modern fluvial sediment from the Limpopo River and dam sediment on the inner shelf. They may also facilitate along-shelf current-induced sediment transport.

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In search of sediment deposits from the Limpopo (Delagoa Bight, southern Africa): Deciphering the catchment provenance of coastal sediments

Cited by 20 publications

References 26 publications

Glacial to interglacial climate variability in the southeastern African subtropics (25–20° S)

Glacial to interglacial climate variability in the southeastern African subtropics (25–20° S)

Glacial to interglacial climate variability in the southeastern African subtropics (25–20° S)

Geological development of the Limpopo Shelf (southern Mozambique) during the last sealevel cycle

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