Structural and sedimentary discontinuities control the generation of karst dissolution cavities in a carbonate sequence, Potiguar Basin, Brazil

2021 ◽  
Vol 123 ◽  
pp. 104753
Author(s):  
Renata E.B. Araújo ◽  
Vincenzo La Bruna ◽  
Andrea Rustichelli ◽  
Francisco H.R. Bezerra ◽  
Milton M. Xavier ◽  
...  
Keyword(s):  
Potiguar Basin ◽  
Carbonate Sequence

scholarly journals Living Benthic Foraminifera from the Surface and Subsurface Sediment Layers Applied to the Environmental Characterization of the Brazilian Continental Slope (SW Atlantic)

Water ◽  
2021 ◽  
Vol 13 (13) ◽  
pp. 1863
Author(s):  
Luciana Cristina de Carvalho Santa-Rosa ◽  
Sibelle Trevisan Disaró ◽  
Violeta Totah ◽  
Silvia Watanabe ◽  
Ana Tereza Bittencourt Guimarães
Keyword(s):  
Continental Slope ◽  
Benthic Foraminifera ◽  
Subsurface Layer ◽  
Environmental Characterization ◽  
Potiguar Basin ◽  
Middle Slope ◽  
Sw Atlantic ◽  
Sediment Layers ◽  
Lower Slope

Living benthic foraminifera (>63 µm) were studied to characterize the continental slope of the Potiguar Basin (SW Atlantic). Foraminifers from the surface (0–2 cm), subsurface (2–5 cm), and integrated (0–5 cm) sediment layers were analyzed to verify their contribution to environmental characterization. It was also estimated if and which changes occur when the subsurface is added. Sampling stations were distributed in five transects in four isobaths (150, 400, 1000, and 2000 m). Sediment samples were fixed with 4% buffered formaldehyde and stained with Bengal rose. Were recorded 396 species in the surface layer, 228 in the subsurface, and 449 in integrating both layers. This study did not include tubular agglutinated species. The assemblages from 150 m isobath indicated the upper slope, from 400 m indicated the middle slope and the ones from the 2000 m indicated the lower slope. The surface layer’s assemblage at 1000 m isobath was more similar to the middle slope; in contrast, its subsurface layer´s assemblage had more similarity with the lower slope. Rarefaction curves, Permanova, and NMDS routines indicated a high resemblance between surface and integrated layers. Therefore, the first two centimeters were sufficient to characterize this region based on living benthic foraminifera.

Five new species of Oncholaimellus (Oncholaimidae: Nematoda) from north-east Brazil, with an emended diagnosis and an updated key to the genus

2014 ◽  
Vol 94 (4) ◽  
pp. 703-727 ◽  
Author(s):  
Patrícia Fernandes Neres ◽  
Maria Cristina da Silva ◽  
Geruso Vieira de Miranda-Júnior ◽  
Verônica Fonsêca-Genevois ◽  
André Morgado Esteves
Keyword(s):  
New Species ◽  
Continental Shelf ◽  
North East ◽  
Potiguar Basin ◽  
Tail Shape ◽  
Emended Diagnosis

Five new species of Oncholaimellus are described. They were found in macrofauna samples from the continental shelf in the Potiguar Basin, north-east Brazil. Cuticular pores with a sclerotized outline associated with a gland were observed in some species. Oncholaimellus multiporus sp. nov. is differentiated from other species by the presence of cuticular pores of different sizes; the smaller pores are abundant and give an appearance of ornamentation. Oncholaimellus intersexus sp. nov. and O. distortus sp. nov. are similar, but differ in the size of the external labial and cephalic setae compared to the corresponding diameter, the presence of the cuticular pores and the tail shape. Oncholaimellus paulus sp. nov. and O. sineporus sp. nov. are similar, although features such as the external labial and cephalic setae size compared to the corresponding diameter and the cuticular pores differentiate between them.

scholarly journals Toe-of-slope facies of the Eocene limestones in Aghioi Pantes sequence (Zakynthos island, Western Greece)

2018 ◽  
Vol 34 (2) ◽  
pp. 699
Author(s):  
Μ. ΚΑΤΗ
Keyword(s):  
Shallow Water ◽  
Debris Flows ◽  
Depositional Environment ◽  
Facies Analysis ◽  
Facies Association ◽  
Gravity Flows ◽  
Carbonate Sequence ◽  
Western Greece ◽  
Water Carbonate ◽  
Water Facies

The facies analysis of the Eocene limestones in the Aghioi Pantes section in central Zakynthos, part of the Preapulian carbonate sequence in the greater area, showed three megafacies types: a) graded beds, in which two main subtypes have been recognized, medium- to thin-bedded calcarenites-calcilutites and thick-bedded ruditic calcarenites, consisting mainly of redeposited shallow-water carbonate sands (mostly bioclasts of nummulites and echinoids); based on their sedimentary structures they have been interpreted as low density turbidite and high density turbidite (or sandy debris flows) deposits correspondingly, b) calcareous conglomerates consisting of shallow-water facies lithoclasts and abundant pelagic intraclasts all of which have been interpreted as debris flow deposits and c) folded strata of pelagic-hemipelagic composition that have been interpreted as slumps. Subsequently, the studied limestones constitute exclusively deep-water resedimented facies having been deposited mainly through sediment gravity flows, carrying significant amounts of shallow-water bio- lithoclastic material. The distribution and the organization of this facies association, with the dominance in particular of the base cut-out turbidites, suggest as depositional environment of the studied Eocene limestones a "low" in the outer slope connecting the Preapulian platform with the adjacent Ionian basin.

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