Deep-Sea Sediments of the Indian Ocean

Schott, W.

doi:10.2110/pec.55.04.0396

Cited by 11 publications

(7 citation statements)

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“…1,000 years calcareous ooze deposition in the Pacific (Revelle et al 1955). The boundary between diatom ooze and subantarctic Globigerina calcareous ooze lies just north of the convergence and roughly parallel to it (Schott 1939).…”

Section: Introductionmentioning

confidence: 95%

Relative Importance of Habitat Variables in Predicting the Distribution of Phytoplankton at the Ecotone of the Antarctic Upwelling Ecosystem

Walsh¹

1971

Ecological Monographs

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The vertical distribution of phytoplankton standing crop, number of species, and community diversity in five transects across the ecotone of the Antarctic Convergence were studied in relation to physical and chemical habitat variables (light, temperature, salinity, density, relative stability, oxygen, phosphate, nitrate, and silicate) and to bacteria and yeasts. Two distinct phytoplankton communities were observed, one north and one south of the convergence. Within the convergence the southern diatomaceous Antarctic community sinks with the formation of Antarctic Intermediate Water and can be traced underneath the northern dinoflagellate subantarctic community by use of indicator species. Chaetoceros bulbosum, Chaetoceros dichaeta, Dactyliosolen antarctica, and Eucampia zoodiacus were used as indicators of the Antarctic community, and Rhizosolenia delicatula, Amphidinium amphidinoides, Oxytoxum variabile, and Phalacroma pulchellum represented the subantarctic community. Submergence of the Antarctic community is corroborated by the vertical distribution of phytoplankton biomass. South of the convergence in the upwelling system, biomass maxima of the phytoplankton consist of Antarctic species. Within the convergence separate subsurface biomass maxima contain the Antarctic community, and both Antarctic and subantarctic species constitute surface maxima of standing crop. In the upper water of the oceanic system north of the convergence, subantarctic species make up most of the biomass, where as small numbers of Antarctic species were observed in the aphotic zone. Surface layers of the euphotic zone in both systems were dominated by a small number of species. Maxima of species number occurred deeper than those of biomass, possibly reflecting the result of competitive exclusion. A low community diversity was observed in the upper water of each area, and a high ecotonal diversity was found at the convergence. A linear multiple regression analysis showed the relative importance of habitat variables in predicting the vertical distribution of the phytoplankton both within the oceanic and upwelling systems and within their transition zone. Water—mass structure, turbulence, light, silicate, and an index of heterotrophic conditions can be used to predict up to 66% of phytoplankton variation across the convergence. Additional prediction can only be achieved by incorporation of biological rate data and nonlinear expression of variable interaction in simulation models based on the present analysis.

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Section: Introductionmentioning

confidence: 95%

Relative Importance of Habitat Variables in Predicting the Distribution of Phytoplankton at the Ecotone of the Antarctic Upwelling Ecosystem

Walsh¹

1971

Ecological Monographs

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“…The influence of pressure (a function of depth) is important. In the deep-sea these factors probably all operate together as discussed by , Bramlette (1961), Schott (1955) and Correns (1937).…”

Section: ) the Radiolaritesmentioning

confidence: 90%

The Geology of Portuguese Timor

1968

Memoirs

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This thesis is an account of the stratigraphy and structure of Portuguese Timor (an area of. 16,000 sq. km.) supported by four geological maps (1:100,000).. Twenty four formations are distinguished, four of' which are allochthbnous. The autochthonous formations range in age from Lower Permian to Recent, and make up a section of 8000 metres thickness.Of the allochthonous formations one is pre-Permian, two are Permian, and the other a midMiocene gravity slide deposit. The lithology and petrography of each formation is described, the fauna and flora recorded, and the environment of deposition discussed.As limestones are the predominant rock type in Timor special attention has been paid to limestone petrography.Five separate periods of folding are recognised, two of which, the Timorean and the Ramelauean, were of major importance and accompanied by large scale overthrusting.

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“…Tethyan condensed sequences are always very pure calcareous deposits, whilst the coeval basinal deposits are more marly and siliceous; this is probably a result of sediment fractionation with clay minerals and siliceous tests being swept into troughs, as well as enhanced solution in the greater depths. It is perhaps not inapposite to compare this with some modern oceanic environments where Globigerina ooze accumulates on ridges and red clay in neighbouring basins (Schott, 1955). Jurassic basinal sequences must have been formed in primary morphological depressions since they may contain allodapic carbonates displaced from ' upslope' (e.g.…”

Section: Contrast With Basinal Successionsmentioning

confidence: 95%

The Genesis of Condensed Sequences in the Tethyan Jurassic

Jenkyns

1971

LET

107

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Pelagic limestones of the west Sicilian Middle Jurassic are used as type examples in this examination of Tethyan condensed sequences. Two main processes were involved in the genesis of this type of deposit: stratigraphic condensation (minimal sediment input) and reworking. The lack of nannoplankton during most of the Jurassic caused stratigraphic condensation, and the particular environment in which these beds were deposited – that of topographic high – was considerably influenced by currents; thus reworking led to a further reduction in sediment thickness. The presence of algal stromatolites in certain condensed sequences and the traces of boring algae in associated ferromanganese nodules suggest deposition within the photic zone. A maximum depth of 200 metres is inferred. Many features of condensed sequences are comparable with those on Recent seamounts; these include presence of ferromanganese nodules and crusts, mixed faunas, calcarenite lenses, algal biscuits, and evidence of submarine solution and lithification. Jurassic Tethyan condensed sequences can thus be interpreted as ancient seamount deposits.

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Deep-Sea Sediments of the Indian Ocean

Cited by 11 publications

References 0 publications

Relative Importance of Habitat Variables in Predicting the Distribution of Phytoplankton at the Ecotone of the Antarctic Upwelling Ecosystem

Relative Importance of Habitat Variables in Predicting the Distribution of Phytoplankton at the Ecotone of the Antarctic Upwelling Ecosystem

The Geology of Portuguese Timor

The Genesis of Condensed Sequences in the Tethyan Jurassic

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