Marine sedimentary environments on some parts of the tropical and equatorial Atlantic margins of Africa during the Late Quaternary

Barusseau, Jean-Paul; Giresse, Pierre; Faure, H.; Lézine, Anne-Marie; Masse, Jean Pierre

doi:10.1016/0278-4343(88)90021-0

Cited by 27 publications

(19 citation statements)

References 4 publications

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“…3) provide a record of Congo palaeodischarge, as fluvial supply of these elements to the fan environment dominates all other mechanisms (Dupont and Agwu, 1991;Jahns, 1996). The pollen taxa have been grouped into ecological assemblages; Cyperaceae and Poaceae dominate the savannah grassland (Stuiver et al, 1998) recommendation for this region; this is supported by a 400-yr offset in oxygen isotopic spikes between this core and uncorrected dates on bulk organic (largely terrestrial) (Barusseau et al, 1988) matter on overlapping sections of nearby core GeoB 1007-4 ( Fig. 1) for the period 12-9 14 C kyr BP.…”

Section: T89-16 Multiproxy Recordsmentioning

confidence: 70%

Integrated marine and terrestrial evidence for abrupt Congo River palaeodischarge fluctuations during the last deglaciation

Marret

Scourse

Versteegh

et al. 2001

J Quaternary Science

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We present a high-resolution reconstruction of tropical palaeoenvironmental changes for the last deglacial transition (18 to 9 cal. kyr BP) based on integrated oceanic and terrestrial proxies from a Congo fan core. Pollen, grass cuticle, Pediastrum and dinoflagellate cyst fluxes, sedimentation rates and planktonic foraminiferal δ 18 O ratios, u K 37 sea-surface temperature and alkane/alkenone ratio data highlight a series of abrupt changes in Congo River palaeodischarge. A major discharge pulse is registered at around 13.0 cal. kyr BP which we attribute to latitudinal migration of the Intertropical Convergence Zone (ITCZ) during deglaciation. The data indicate abrupt and short-lived changes in the equatorial precipitation regime within a system of monsoonal dynamics forced by precessional cycles. The phases of enhanced Congo discharge stimulated river-induced upwelling and enhanced productivity in the adjacent ocean.

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Section: T89-16 Multiproxy Recordsmentioning

confidence: 70%

Integrated marine and terrestrial evidence for abrupt Congo River palaeodischarge fluctuations during the last deglaciation

Marret

Scourse

Versteegh

et al. 2001

J Quaternary Science

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“…The South Atlantic Central Water is the main source of nutrient-rich water masses, leading to a 50-70 km wide coastal band of intensive upwelling (Hagen, 1981(Hagen, , 2000Lutze and Coulbourn, 1984;Helmke et al, 2005). The northern-most site GeoB 9510 is located between the Senegal River and Dakar, where terrigenous silty-clayey muds dominate (Barusseau et al, 1988;Mulitza et al, 2006). GeoB sites 9519 and 9518 are located slightly south between Dakar and the Gambia River.…”

Section: Study Area and Sampling Sitesmentioning

confidence: 99%

Benthic phosphorus and iron budgets for three NW African slope sediments: a balance approach

2010

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Abstract. Despite intensive research on the different domains of the marine phosphorus (P) cycle during the last decades, frequently discussed open questions still exist especially on controlling factors for the benthic behaviour of P and its general distribution in sediment-pore water systems. Steady state or the internal balance of all relevant physical and (bio)geochemical processes are amongst the key issues. In this study we present and discuss an extended data set from surface sediments recovered from three locations on the NW African continental slope. Pore water data and results from sequential sediment extractions give clear evidence to the well-known close relationship between the benthic cycles of P and iron. Accordingly, most of the dissolved phosphate must have been released by microbially catalyzed reductive dissolution of iron (oxhydr)oxides. However, rates of release and association of P and iron, respectively, are not directly represented in profiles of element specific sediment compositions. Results from steady-state based transport-reaction modelling suggest that particle mixing due to active bioturbation, or rather a physical net downward transport of P associated to iron (oxyhydr)oxides, is an essential process for the balance of the inspected benthic cycles. This study emphasizes the importance of balancing analytical data for a comprehensive understanding of all processes involved in biogeochemical cycles.

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“…The resulting sequence is aggrading and relates to the`keep-up' growth style, in the sense of Schlager (1981), Davies and Montaggioni (1985), NeuFig. 4 Primary productivity, carbonate production and upwelling intensity during the post-glacial transgression along the West African shelf (after Barusseau et al 1988) mann and MacIntyre (1985) and Sarg (1988), and characterizes high water energy reef-edge zones (Montaggioni 1988). The response of the Papeete barrier reef (Tahiti) to the post-glacial sea-level rise conspicuously illustrates this`keep-up' mode .…”

Section: Features Linked To Increasing Accommodationmentioning

confidence: 97%

Growth history of shallow-water carbonates: control of accommodation on ecological and depositional processes.

Massé¹,

Montaggioni²

2000

Int J Earth Sci

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We explore the role played on the growth of shallow-water carbonates by changes in accommodation using case studies from Late Quaternary to modern carbonate environments, i.e. coral reefs and carbonate platforms and ramps. Accommodation appears not to influence either primary productivity or community structure (K-versus r-strategists) as these are directly governed by nutrient supply; but it does control submarine depositional profiles and their stratigraphic expression (i.e. volumetric sedimentary partitioning). The growth of communities from incipient to senescent stages is dictated by relative rates of sea-level variations, although ambient temperatures and trophic conditions may modify the community response. A decrease or stabilization of accommodation favours lateral migration, thus generating ecological and sedimentary innovations. Organic carbon production tends to be positively correlated to that of carbonate, both declining as accommodation decreases. Shallow water carbonates develop as a result of the interplay of factors, including the types and rates of biological and physical processes. Applying depositional models of Recent shallow-water carbonates to the interpretation of ancient carbonate platforms first needs to acknowledge the respective role of the two contrasting phases that operated during the post-glacial sea-level rise (an earlier, fast-rising phase versus a later, slowly rising to stabilizing phase); the period of relative sea-level stabilization (i.e. the past 6,000 years) appears a relevant reference for stillstand-related carbonate systems. Furthermore, the oligotrophic nutrient model, a dominant feature of the modern shallow-water tropics, can be used as an analogue in reconstructing carbonate growth histories during greenhouse episodes of Earth history.

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Marine sedimentary environments on some parts of the tropical and equatorial Atlantic margins of Africa during the Late Quaternary

Cited by 27 publications

References 4 publications

Integrated marine and terrestrial evidence for abrupt Congo River palaeodischarge fluctuations during the last deglaciation

Integrated marine and terrestrial evidence for abrupt Congo River palaeodischarge fluctuations during the last deglaciation

Benthic phosphorus and iron budgets for three NW African slope sediments: a balance approach

Growth history of shallow-water carbonates: control of accommodation on ecological and depositional processes.

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