South African Climates (Agulhas LGM Density Profile)

Hall, Ian R; Hemming, S. R.; LeVay, Leah J.; Scientists, Expedition

doi:10.14379/iodp.proc.361.2017

Cited by 15 publications

(14 citation statements)

References 157 publications

(257 reference statements)

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“…Sediment core IODP Expedition 361 Site U1476 Holes A, D and E (15° 49.25′ S; 41° 46.12′ E, at 2,166 m water depth) yielded a continuous spliced section with a total length of about 242 m. All sample depths are reported against the shipboard spliced core composite depth below sea floor (CCSF) 14,51 . Site U1476 is situated on the eastern flank of the Davie Ridge at the northern entrance of the Mozambique Channel near DSDP Site 242.…”

Section: Methodsmentioning

confidence: 99%

“…Site U1476 is situated on the eastern flank of the Davie Ridge at the northern entrance of the Mozambique Channel near DSDP Site 242. The dominant greenish grey sediments are mainly composed of calcareous nannofossils and foraminifera with moderate amounts of lithogenic sediments (on average less than 58%) and notable occurrences of fine to medium sand 14,51 .…”

Section: Methodsmentioning

confidence: 99%

“…1). This MCT flow-speed record is based on lithogenic properties of sediments in a marine core retrieved from International Ocean Discovery Program (IODP) Site U1476 (15° 49.25′ S, 41° 46.12′ E, at 2,166 m water depth) 14 at the Davie Ridge, a bathymetric high in the narrows of the Mozambique Channel (Fig. 1).…”

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confidence: 99%

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Indo-Pacific Walker circulation drove Pleistocene African aridification

Lubbe

Hall

Barker

et al. 2021

Nature

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Section: Methodsmentioning

confidence: 99%

Section: Methodsmentioning

confidence: 99%

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Indo-Pacific Walker circulation drove Pleistocene African aridification

Lubbe

Hall

Barker

et al. 2021

Nature

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“…IODP Site U1475 (41°25.61′S; 25°15.64′E, 2,669 mbsl) is located south of Africa on the southwestern flank of the Agulhas Plateau (Figure 1) (Hall, Hemming, LeVay, Barker, Berke, Brentegani et al, 2017). Site U1475 offers a strategic location to study latitudinal migrations of the STF; it currently lies between the far northern edge of the modern STF and the ARC path (Hall, Hemming, LeVay, Barker, Berke, Brentegani et al, 2017;Hall, Hemming, LeVay, Barker, Berke, Caley et al, 2017). Sediments recovered using an advanced piston coring system from Holes U1475B, U1475C, U1475E, and U1475F were spliced together to generate a continuous sequence (∼292 m CCSF) based on RGB blue, b* color reflectance, and natural gamma radiation (NGR) data (Hall, Hemming, LeVay, Barker, Berke, Brentegani et al, 2017;Hall, Hemming, LeVay, Barker, Berke, Caley et al, 2017).…”

Section: Site U1475mentioning

confidence: 99%

“…Site U1475 offers a strategic location to study latitudinal migrations of the STF; it currently lies between the far northern edge of the modern STF and the ARC path (Hall, Hemming, LeVay, Barker, Berke, Brentegani et al, 2017;Hall, Hemming, LeVay, Barker, Berke, Caley et al, 2017). Sediments recovered using an advanced piston coring system from Holes U1475B, U1475C, U1475E, and U1475F were spliced together to generate a continuous sequence (∼292 m CCSF) based on RGB blue, b* color reflectance, and natural gamma radiation (NGR) data (Hall, Hemming, LeVay, Barker, Berke, Brentegani et al, 2017;Hall, Hemming, LeVay, Barker, Berke, Caley et al, 2017). In total 352 samples were selected from the interval of the splice spanning from 1.4-0.3 Ma to generate organic geochemistry records at the Agulhas Plateau with an average resolution of approximately 3 kyr.…”

Section: Site U1475mentioning

confidence: 99%

Latitudinal Migrations of the Subtropical Front at the Agulhas Plateau Through the Mid‐Pleistocene Transition

Cartagena‐Sierra

Berke

Robinson

et al. 2021

Paleoceanog and Paleoclimatol

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The meridional variability of the Subtropical Front (STF) in the Southern Hemisphere, linked to expansions or contractions of the Southern Ocean, may have played an important role in global ocean circulation by moderating the magnitude of water exchange at the Indian-Atlantic Ocean Gateway, so called Agulhas Leakage. Here we present new biomarker records of upper water column temperature ( K' 37 U and 86 TEX ) and primary productivity (chlorins and alkenones) from marine sediments at IODP Site U1475 on the Agulhas Plateau, near the STF and within the Agulhas retroflection pathway. We use these multiproxy time-series records from 1.4 to 0.3 Ma to examine implied changes in the upper oceanographic conditions at the mid-Pleistocene transition (MPT, ca. 1.2-0.8 Ma). Our reconstructions, combined with prior evidence of migrations of the STF over the last 350 ka, suggest that in the Southwestern Indian Ocean the STF may have been further south from the Agulhas Plateau during the mid-Pleistocene Interim State (MPIS, MIS 23-12) and reached its northernmost position during MIS 34-24 and MIS 10. Comparison to a Globorotalia menardii-derived Agulhas Leakage reconstruction from the Cape Basin suggests that only the most extreme northward migrations of the STF are associated with reduced Agulhas Leakage. During the MPIS, STF migrations do not appear to control Agulhas Leakage variability, we suggest previously modeled shifting westerly winds may be responsible for the patterns observed. A detachment between STF migrations and Agulhas Leakage, in addition to invoking shifting westerly winds may also help explain changes in CO 2 ventilation seen during the MPIS.CARTAGENA-SIERRA ET AL.

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The impact of internal waves on upper continental slopes: insights from the Mozambican margin (southwest Indian Ocean)

Miramontes

Jouet

Thereau

et al. 2020

Earth Surf Processes Landf

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Evidences of sedimentation affected by oceanic circulation, such as nepheloid layers and contourites are often observed along continental slopes. However, the oceanographic processes controlling sedimentation along continental margins remain poorly understood. Multibeam bathymetry and high‐resolution seismic reflection data revealed a contourite depositional system in the Mozambican upper continental slope composed of a contourite terrace (a surface with a gentle seaward slope dominated by erosion) and a plastered drift (a convex‐shape sedimentary deposit). A continuous alongslope channel and a field of sand dunes (mainly migrating upslope), formed during Holocene, were identified in the contourite terrace at the present seafloor. Seismic reflection data of the water column show internal waves and boluses propagating in the pycnocline near the upper slope. The channel and the dunes are probably the result of the interaction of the observed internal waves with the seafloor under two different conditions. The alongslope channel is located in a zone where intense barotropic tidal currents may arrest internal solitary waves, generating a hydraulic jump and focused erosion. However, upslope migrating dunes may be formed by bottom currents induced by internal solitary waves of elevation propagating landwards in the pycnocline. These small‐scale sedimentary features generated by internal waves are superimposed on large‐scale contouritic deposits, such as plastered drifts and contourite terraces, which are related to geostrophic currents. These findings provide new insights into the oceanographic processes that control sedimentation along continental margins that will help interpretation of palaeoceanographic conditions from the sedimentary record. © 2020 The Authors. Earth Surface Processes and Landforms published by John Wiley & Sons Ltd

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South African Climates (Agulhas LGM Density Profile)

Cited by 15 publications

References 157 publications

Indo-Pacific Walker circulation drove Pleistocene African aridification

Indo-Pacific Walker circulation drove Pleistocene African aridification

Latitudinal Migrations of the Subtropical Front at the Agulhas Plateau Through the Mid‐Pleistocene Transition

The impact of internal waves on upper continental slopes: insights from the Mozambican margin (southwest Indian Ocean)

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