Quaternary deposits on the South Barbados accretionary prism

1991 ◽  
Vol 96 (3-4) ◽  
pp. 247-267 ◽  
Author(s):  
J.C. Faugères ◽  
E. Gonthier ◽  
L. Masse ◽  
M. Parra ◽  
J.C. Pons ◽  
...  
Keyword(s):  
Accretionary Prism ◽  
The South ◽  
Quaternary Deposits

Contribution a l'etude du Quaternaire des Idjibitene et de la bordure meridionale de l'Adrar (El Gletat, Mauritanie)

1966 ◽  
Vol S7-VIII (5) ◽  
pp. 749-759
Author(s):  
Maurice Taieb
Keyword(s):  
The South ◽  
Quaternary Deposits ◽  
Southern Border ◽  
White Sands ◽  
Southwest Border

Abstract Two morphologically different regions are distinguished in the Quaternary of the Idjibitene mountains and along the southern border of the Adrar (El Gletat, Mauritania). Along the south and southwest border of the Adrar, deposits resulting from slope erosion are observed; to the south, dune structures and lake formations with white sands, brown sands, rare ferruginous crusts, and sand cemented by calcite (tarous) are seen. By observation of the terrain, collection of in place Acheulean industries, and study of the sands (granulometric and morphometric) it has been possible to reach an understanding of the stratigraphy. A chronology of Quaternary deposits of the Idjibitene is proposed. Close analogies with the Quaternary formations of Majabat are established.

scholarly journals The Col-Gully and Glacial Deposits at Court Hill, Clevedon, Near Bristol, England

1978 ◽  
Vol 20 (82) ◽  
pp. 173-188 ◽  
Author(s):  
D. D. Gilbertson ◽  
A. B. Hawkins
Keyword(s):  
Ice Sheet ◽  
Quaternary Geology ◽  
The South ◽  
Quaternary Deposits ◽  
Glacial Deposits ◽  
Complex Sequence ◽  
Water And Sediment ◽  
Sandy Silt ◽  
Carboniferous Limestone

AbstractAn outline is given of the Quaternary geology and geomorphology of Court Hill Col in Failand Ridge near Clevedon, Avon County, from observations made during the construction of the M5 Motorway.A glacial col-gully about 100 m wide and approximately 25 m deep is described. The col-gully, eroded through the Carboniferous Limestone, opens and deepens northward. Associated with the Col and the col-gully is a complex sequence of Quaternary deposits. Uppermost in the sequence is a layer of red sandy silt (cover sand) approximately 0.5 m thick, of periglacial origin, probably of Devensian (Weichselian) age. Largely confined to the col-gully are unstratified tills, stratified ice-contact deposits and glacio-lacustrine deltaic deposits. The glaciogenic deposits are up to 25 m thick. Boulders of about 8 Mg in weight have been observed.The geomorphology of the col-gully, and the stratification and composition of the glaciogenic deposits, demonstrate that an ice sheet at least 85 m thick had impinged against the south flank of Failand Ridge and was discharging immense quantities of water and sediment down an ice-contact slope through the Col into a small ice-marginal lake north of the col-gully. The ice sheet is regarded as being Wolstonian, or Anglian, in age.The precise origins of the col-gully and the interpretation of the glacial sequence are not yet completely clear. However, it is believed that the balance of evidence indicates that both the col-gully itself and the glaciogenic deposits represent a complex sub-, en- and pro-glacial sequence associated with the downwasting and division of an ice mass into two parts by the "emergence" of Failand Ridge. The possible extent and geomorphological implications of ice-sheet penetration into the Bristol area are briefly discussed.

A new fossil cricetid (Rodentia, Sigmodontinae) from northeastern Brazil with remarks on small mammal extinctions in the tropical Quaternary

2020 ◽  
Vol 101 (4) ◽  
pp. 1133-1147
Author(s):  
Simone B das Neves ◽  
Ulyses F J Pardiñas ◽  
Patrícia Hadler ◽  
Elver L Mayer ◽  
Ana M Ribeiro
Keyword(s):  
New Species ◽  
South America ◽  
Small Mammal ◽  
Late Quaternary ◽  
Northeastern Brazil ◽  
The South ◽  
Quaternary Deposits ◽  
Extant Species ◽  
Genetic Features ◽  
History Of

Abstract The rare cricetid rodent Bibimys Massoia, 1980 contains three extant species that are distributed in the lowlands of eastern South America between 35°S and 20°S and distinguished mostly by subtle morphological and genetic features. Several fragmented jaws belonging to this genus were recovered from Late Quaternary deposits located in northeastern Brazil, forming part of a rich archaeological and paleontological small mammal assemblage that has been recovered from caves in the Serra da Capivara, state of Piauí. This material is described herein as belonging to a new species, the most hypsodont member of the genus. The specimens also represent an extralimital occurrence of this sigmodontine, as the nearest extant population of Bibimys is ~1,200 km to the south. Because there are few reliable records of extinct small mammals from the Pleistocene–Holocene transition on the South American continent, in describing this new sigmodontine we extend the records of past biodiversity preserved in the Quaternary deposits of tropical South America. This new species likewise highlights that the Serra da Capivara deposits are promising for understanding the evolutionary history of cricetid rodents.

scholarly journals Deciphering the metamorphic evolution of the Pulo do Lobo metasedimentary domain (SW Iberian Variscides)

Solid Earth ◽  
2020 ◽  
Vol 11 (2) ◽  
pp. 469-488 ◽  
Author(s):  
Irene Pérez-Cáceres ◽  
David Jesús Martínez Poyatos ◽  
Olivier Vidal ◽  
Olivier Beyssac ◽  
Fernando Nieto ◽  
...  
Keyword(s):  
B Cell ◽  
Microstructural Analysis ◽  
Carbonaceous Material ◽  
Accretionary Prism ◽  
Low Pressure ◽  
White Mica ◽  
Cell Dimension ◽  
Low Grade ◽  
The South ◽  
Metamorphic Evolution

Abstract. The Pulo do Lobo domain is one of the units exposed within the orogenic suture zone between the Ossa-Morena and the South Portuguese zones in the SW Iberian Variscides. This metasedimentary unit has been classically interpreted as a Rheic subduction-related accretionary prism formed during pre-Carboniferous convergence and eventual collision between the South Portuguese Zone (part of Avalonia) and the Ossa-Morena Zone (peri-Gondwanan terrane). Discrete mafic intrusions also occur within the dominant Pulo do Lobo metapelites, related to an intra-orogenic Mississippian transtensional and magmatic event that had a significant thermal input. Three different approaches have been applied to the Devonian–Carboniferous phyllites and slates of the Pulo do Lobo domain in order to study their poorly known low-grade metamorphic evolution. X-ray diffraction (XRD) was used to identify the mineralogy and measure crystallographic parameters (illite “crystallinity” and K-white mica b-cell dimension). Compositional maps of selected samples were obtained from electron probe microanalysis, which allowed for processing with XMapTools software, and chlorite semiempirical and thermodynamic geothermometry was performed. Thermometry based on Raman spectroscopy of carbonaceous material (RSCM) was used to obtain peak temperatures. The microstructural study shows the existence of two phyllosilicate growth events in the chlorite zone, the main one (M1) related to the development of a Devonian foliation S1 and a minor one (M2) associated with a crenulation cleavage (S2) developed in middle–upper Carboniferous times. M1 entered well into epizone (greenschist facies) conditions. M2 conditions were at lower temperature, reaching the anchizone–epizone boundary. These data accord well with the angular unconformity that separates the Devonian and Carboniferous formations of the Pulo do Lobo domain. The varied results obtained by the different approaches followed, combined with microstructural analysis, provide different snapshots of the metamorphic history. Thus, RSCM temperatures are higher in comparison with the other methods applied, which is interpreted to reflect a faster re-equilibration during the short-lived thermal Mississippian event. Regarding the metamorphic pressure, the data are very homogeneous: very low celadonite content (0 %–10 %) in muscovite (and low values of K-white mica b-cell dimension; 8.995 Å mean value), indicating a low pressure–temperature gradient, which is unexpected in a subduction-related accretionary prism. Highlights A multidisciplinary approach has been applied to study the metamorphism of the Pulo do Lobo metapelites. Devonian metamorphism entered epizone conditions. Carboniferous metamorphism reached the anchizone–epizone boundary. The inferred low-pressure gradient is incompatible with a subduction-related accretionary prism.

Observations sur la bordure occidentale de la Bresse, region de Pont-de-Vaux (Ain)

1951 ◽  
Vol S6-I (4-6) ◽  
pp. 265-275
Author(s):  
Philibert Russo
Keyword(s):  
The South ◽  
The West ◽  
Quaternary Deposits ◽  
Crustal Movements ◽  
Tectonic Processes ◽  
West Central

Abstract Presents data on the distribution of the Pliocene and Quaternary in the western part of the Bresse region, France, obtained from 40 well borings, ranging from 7 to 17 meters in depth, in the vicinity of Pont-de-Vaux. Valleys cut in the Plaisancian (lower Pliocene) blue clays during later Pliocene times are filled with Quaternary deposits. The changes in level causing dissection and filling seem to have been produced by tectonic processes associated with the Alpine crustal movements, which caused subsidence in the west-central part of the region and uplift in the south, rather than by eustaticmovements.

Sr-Nd isotopes as tracers of fine-grained detrital sediments: the South-Barbados accretionary prism during the last 150 kyr

1997 ◽  
Vol 136 (3-4) ◽  
pp. 225-243 ◽  
Author(s):  
Mario Parra ◽  
Jean-Claude Faugères ◽  
Francis Grousset ◽  
Claude Pujol
Keyword(s):  
Accretionary Prism ◽  
The South ◽  
Nd Isotopes ◽  
Fine Grained

scholarly journals The Mesohellenic trough and the Thrace Basin. Two Tertiary molassic Basins in Hellenides: do they really correlate?

2017 ◽  
Vol 47 (2) ◽  
pp. 551
Author(s):  
Ad. Kilias ◽  
A. Vamvaka ◽  
G. Falalakis ◽  
A. Sfeikos ◽  
E. Papadimitriou ◽  
...  
Keyword(s):  
Structural Data ◽  
Accretionary Prism ◽  
Strike Slip ◽  
Geological Mapping ◽  
Upper Eocene ◽  
Calc Alkaline ◽  
Quaternary Deposits ◽  
Upper Oligocene ◽  
Thrace Basin ◽  
Oblique Convergence

Based on lithostratigraphic and structural data, as well as geological mapping, the mollasic Thrace Basin (ThB) in NE Greece (including the Paleogene deposits of the Axios Basin) was compared with the Mesohellenic Trough (MHT) in NW Greece. Both basins are characterized by a thick sedimentary sequence of molassic-type strata (3-5km thickness) of Tertiary age, overlain unconformably by Miocene- Pliocene and Quaternary deposits. Molassic sedimentation started almost simultaneously in both areas during the Mid-Upper Eocene but it finished in different time, in the Mid-Upper Miocene for the MHT and the Upper Oligocene for the ThB, respectively. Sedimentation in ThB was also linked with an important calc-alkaline and locally shoshonitic magmatism of Eocene-Oligocene age. We interpreted the MHT as a polyhistory strike-slip and piggy-back basin, above westward-emplacing ophiolites and Pelagonian units on the cold Hellenic accretionary prism. In contrast to MHT, the ThB evolved as a Paleogene supra-detachment basin above the strongly extended during the Eocene-Oligocene Hellenic Hinterland. The syn-depositional magmatic products, linked possibly with subduction processes in Pindos or Axios ocean(s). In any case, MHT and ThB are related to inferred oblique convergence of the Apulia plate and the internal Hellenic units.

scholarly journals REMARKS ON THE KARSTIFICATION IN THE WIDER AREA OF THE UPPER MESSINIA CLOSED HYDROGEOLOGICAL BASIN (SW PELOPONNESUS, GREECE)

2017 ◽  
Vol 43 (4) ◽  
pp. 1785 ◽  
Author(s):  
I. Mariolakos ◽  
E. Spyridonos
Keyword(s):  
Water Flow ◽  
Upper Cretaceous ◽  
Fault Zones ◽  
Karstic Aquifer ◽  
The South ◽  
Quaternary Deposits ◽  
The North ◽  
Hydraulic Conditions ◽  
Underground Flow ◽  
Hydrogeological System

The Upper Messinia Basin is part of the Kalamata - Kyparissia graben structure, defined by two fault zones, one of E-W direction to the north and one of N-S direction to the east. The Tripolis and the Pindos alpidic units build up the basement of the region, and are covered by post-alpidic Pleistocene and quaternary deposits. The Basin is a closed hydrogeological system. In the upper cretaceous Pindos limestones, we observe two different karst types, according to drilling results. In the western part of the basin, where the limestones appear on the surface, the merokarst type is observed and water flow is limited in separated karstic conduits. On the contrary, in the central part of the basin, where the limestones underlie the clastic post-alpidic formations, the holokarst type is observed and a rich karstic aquifer is developed. This is explained by the closed hydraulic conditions. In the western part of the basin the karstic aquifer is unconfined, while in the central part it is confined, due to the overlying impermeable post-alpidic sediments and the overall closure of underground flow to the south. It appears that the confined conditions led to the development from merokarst to holokarst in this region.

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