Age relationships of distributary channels on Amazon deep-sea fan: Implications for fan growth pattern

Damuth, John E.; Kowsmann, Renato Oscar; Flood, Roger D.; Belderson, R. H.; Gorini, Marcus Aguiar

doi:10.1130/0091-7613(1983)11<470:arodco>2.0.co;2

Cited by 85 publications

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“…It is located on a flat terrace on the western levee of the Channel-levee System 5 (acoustic stratigraphic nomenclature defined by Damuth et al, 1983, and, at about 1 km east of the channel (Fig. 1).…”

Section: Clay Mineral Record Of a Quaternary Channel-levee System Locmentioning

confidence: 99%

“…During glacial low sea-level stands, the river discharged directly into the submarine canyon which crossed the continental slope and led to a large sinuous channel-levee system. This submarine topography is fairly well known due to extensive survey, swath-mapping bathymetry (SeaBeam) and deep-water side-scan sonar (GLORIA; Damuth et al, 1983;Manley and Flood, 1988). By contrast, the lithology and age of the late Neogene to Quaternary sediments that make up these systems, as well as the relationships between these systems and sea-level changes, were, until recently, rather poorly defined because of the lack of drilling cores.…”

Section: Introductionmentioning

confidence: 99%

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Clay mineral distribution and significance in Quaternary sediments of the Amazon Fan

Debrabant¹,

López²,

Chamley³

1997

Proceedings of the Ocean Drilling Program, 155 Scientific Results

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The clay mineral assemblages of samples from the Amazon Fan were investigated in middle Pleistocene to Holocene sediments from 16 Ocean Drilling Program Leg 155 sites and were placed in lithologic successions to study continental evolution and transport conditions. The sediments sampled along a transect parallel to the main channel reflect moderate differential settling processes, whereas those studied along a transect roughly parallel to the coast clearly suggest winnowing effects related to the North Brazil Current. High-resolution analyses of Holocene deposits reflect the dominant influence of downstream soil erosion relative to supply from the Andean range and the progressive increase of soil-derived relative to rock-derived outputs. The middle Pleistocene to uppermost Pleistocene and Holocene successions are marked by a constantly warm climatic background and by noticeable modifications in the rock-derived (illite, chlorite) and soil-derived (smectite, kaolinite) products. These products successively reflect sea-level changes, tectonic rejuvenation in the Andean range, regressive erosion, and rainfall increase.

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Section: Clay Mineral Record Of a Quaternary Channel-levee System Locmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Clay mineral distribution and significance in Quaternary sediments of the Amazon Fan

Debrabant¹,

López²,

Chamley³

1997

Proceedings of the Ocean Drilling Program, 155 Scientific Results

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“…2, 3). Because the spatial distribution of these units is very well constrained on the Amazon Fan (Damuth et al, 1983a(Damuth et al, , 1983bDamuth et al, 1988;Manley and Flood, 1988;Flood et al, 1991;Pirmez, 1994;Pirmez and Flood, 1995;, average grain-size profiles for each acoustic unit, both downfan and crossfan, can be constructed from the drilled sites.…”

Section: Comparison With Acoustic Unitsmentioning

confidence: 99%

“…The channel axes are associated with high-amplitude reflections (HARs, Kastens and Shor, 1985) on seismic reflection profiles. The relative age relationships of the systems were determined for the surficial channels by overlapping stratigraphic relationships (named 1 through 6C; Damuth et al, 1983aDamuth et al, , 1983bDamuth et al, , 1988Damuth and Flood, 1984), whereas the stratigraphy of buried channel-levee systems used overlapping stratigraphic relationships as well as depth to levee crests (given color names; Manley and Flood, 1988) (Table 1; Figs. 1, 2).…”

Section: Introductionmentioning

confidence: 99%

Grain-size characterization of Amazon Fan deposits and comparison to seismic facies units

Manley¹,

Pirmez²,

Busch³

et al. 1997

Proceedings of the Ocean Drilling Program, 155 Scientific Results

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Prior to Ocean Drilling Program Leg 155, the architecture of the Amazon Fan, as well as those of other modern submarine fans, had been investigated primarily by seismic reflection profiles. The acoustic facies and stratal patterns observed on these profiles provided a wealth of information that allowed deciphering fan growth patterns and the geometry of fan deposits. However, lithofacies could only be inferred from the seismic reflection data. Here we analyze grain-size data from 13 sites drilled during Leg 155, and place the results in the context of the stratigraphic units interpreted from seismic reflection data. Clay, silt, and fine sand are the dominant grain sizes of all cores retrieved from the Amazon Fan. In this mud-rich fan, sand is concentrated within the channel thalweg, at the base of channel-levee systems within the middle fan, and forms a significant fraction of the lower fan deposits drilled. All channel-levee deposits drilled are characterized by a fining-upward trend and by an overall coarsening in the downfan direction. Downfan coarsening of the levee deposits probably results from very efficient sorting associated with the channelized flow of turbidity currents together with the overall decrease in channel relief downfan. Finingupward cycles within a channel-levee system are observed in the middle fan where multiple phases of levee development are stacked upon each other. Each growth phase is marked by an abrupt coarsening that marks a channel bifurcation occurring downslope, followed by a fining-upward sequence of levee aggradation. Channel bifurcation results in the reworking of older channel deposits, and the formation of laterally widespread units. High-amplitude reflections (HARs) beneath the channel axis and high-amplitude reflection packet (HARPs) units are composed of two distinct grain-size populations. HARs and HARPs are the coarsest units that form the fan, with sizes up to 0 ø. Both units display an overall coarsening downfan. These characteristics are likely the result of multistep transport of sand downfan. Thick acoustically transparent units on seismic profiles are correlated to large mass-transport deposits, displaying grain-size characteristics similar to levee deposits with an overall finingupward and downfan-coarsening trend.

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“…35). Hole 93IB was drilled to 421.3 mbsf through Channel-levee System 5 (Damuth et al, 1983) and into a channel-levee system that is part of the Bottom Levee Complex . Five moderate-to high-amplitude reflections mark the boundaries between six seismic-facies units and are identified at 20, 35, 180, 290, and 410 ms sub-bottom (Fig.…”

Section: Core-seismic Integrationmentioning

confidence: 99%

Site 931

1995

Proceedings of the Ocean Drilling Program

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Principal results: Site 931 (proposed Site AF-10) is the most easterly site to be drilled on the Amazon Fan. It is located on a flat terrace on the western levee of the buried Channel 5 system. The holes penetrate a thin acoustic unit interpreted as muds with minor turbidite silt overlying the Channel 5 system, then the thick Channel 5 levee sequence passing down into highamplitude reflection packets (HARPs) interpreted as sandy lobes associated with channel avulsion. Three HARP units overlie a thick acoustically incoherent unit (interpreted as a debris flow) that laps out to the west against the crest of the unusually thick Bottom Levee Complex. The site was selected from a Ewing seismic profile (E9209; 1637UTC on 20 Sept.). Following Site 930, we ran a 12-hr seismic survey across proposed Sites 940, 932,933, and 931.Hole 931A was cored to 53.6 mbsf and recovered 56.99 m. Hole 931B was cored by advanced piston corer (APC) to 76.8 mbsf, then by extended core barrel (XCB) to 421.3 mbsf. Recovery was poor from 142.2 to 219.1 mbsf (15.6%) in alternating sand and mud. Total hole recovery was 296.1 m (70.3%). Temperature measurements were obtained using the ADARA at 67.3 mbsf, and using the WSTP at 103.5 mbsf and 142.2 mbsf, yielding a mean geothermal gradient of 34°/km. There was gas expansion in many cores. Methane was found throughout the hole, with a sharp increase at 10 mbsf, and peaks at about 50 mbsf and 400 mbsf. Only trace amounts of ethane and propane were detected in a few deep cores.Because some pipe had to be raised to retrieve a stuck core barrel, Hole 93IB was conditioned for logging prior to taking the final two cores. On the first logging run, the sonic and natural gamma tools of the Quad combo flooded. They were replaced, and the tool was run to 251 mbsf where a bridge prevented further passage downhole. The hole was logged from 251 to 90 mbsf, the pipe was raised to 72 mbsf, and the interval 150 to 72 mbsf was logged. A similar procedure was used on subsequent log runs with the FMS, geochemical, and GHMT combinations. Hole condi-123 SITE 931 tions were good, except in a few parts of the interval from 140 to 240 mbsf, where sand beds had washed out. Hole 931C was then cored to 32.6 mbsf and recovered 34.43 m (105.6% recovery).Five lithologic units are recognized: Unit I (0-0.57 mbsf) is a Holocene nannofossil-and foraminifer-rich clay that is bioturbated and contains about 50% carbonate.Unit II (0.57-189.63 mbsf) consists of mud with interbedded laminae and beds of silt and very fine sand. The mud contains about 3% carbonate. Subunit IIA (0.57-6.70 mbsf) comprises bioturbated and color-banded mud. Subunit IIB (6.70-27.50 mbsf) consists of mud with <20% silt laminae. These two subunits represent sediment that accumulated since the abandonment of Channel 5. Subunit IIC (27.50-199.20 mbsf), corresponding to the crest of the Channel 5 levee, contains mud with thin to thick beds of silt and fine sand, which increase in frequency and thickness toward the base of the subunit. The thickest sand beds contain...

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Age relationships of distributary channels on Amazon deep-sea fan: Implications for fan growth pattern

Cited by 85 publications

References 0 publications

Clay mineral distribution and significance in Quaternary sediments of the Amazon Fan

Clay mineral distribution and significance in Quaternary sediments of the Amazon Fan

Grain-size characterization of Amazon Fan deposits and comparison to seismic facies units

Site 931

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