References of "Steemans, Philippe"
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See detailLlandovery biostratigraphy of the Paraná Basin, East Paraguay
Mendlowicz Mauller, P.; Pereira, E.; Grahn, Y. et al

Conference (2004)

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See detailPalynology of the Jauf Formation from the Northeastern part of the Arabian Shield
Al-Ruwaili, M.; Breuer, P.; Higgs, K. et al

Conference (2004)

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See detailAnálise bioestratigráfica do intervalo Llandoveriano da Bacia do Paraná no Paraguai Oriental
Mendlowicz Mauller, P.; Pereira, E.; Grahn, Y. et al

in Revista Brasiliera de Paleontologia (2004), 7(1), 199-212

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See detailA Psammosteid Heterostracan (Vertebrata: Pteraspidomorphi) from the Emsian (Lower Devonian) of the Grand Duchy of Luxembourg
Delsate, D.; Blieck, A.; Steemans, Philippe ULg

in Geologica Belgica (2004), 7(1-2), 21-26

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See detailThe plant Leclercqia (Lycopsida) in Gondwana: implications for reconstructing Middle Devonian palaeogeography
Meyer-Berthaud, B.; Fairon-Demaret, Muriel ULg; Steemans, Philippe ULg et al

in Geological Magazine (2003), 140(2), 119-130

Abundant and well-preserved material of the ligulate lycopsid genus Leclercqia is reported from a new Middle Devonian locality in northeastern Queensland (Australia). The plants occur in a chert horizon ... [more ▼]

Abundant and well-preserved material of the ligulate lycopsid genus Leclercqia is reported from a new Middle Devonian locality in northeastern Queensland (Australia). The plants occur in a chert horizon in the Storm Hill Sandstone of the Dosey-Craigie Platform. Lithological data and conodont analyses combined with information from in situ spores provide an age for the plant levels ranging from Eifelian, possibly Middle Eifelian, to Early Givetian. Plant taxonomic identification is based on vegetative and fertile stems that display both external morphology and anatomy. This material represents the best documented occurrence of Leclercqia outside Laurussia and possibly the earliest in Gondwana; it provides evidence that colonization of Gondwana by the species L. complexa was contemporaneous to that of Siberia and Kazakhstan. Analysis of the distribution patterns of L. complexa suggests that it was adapted to a wide range of environments, but within certain limits which we hypothesize to be those of a climatic belt. Such considerations support previous studies using other biological data, such as faunas and palynomorphs, for reconstructing Devonian palaeogeography. They favour a close proximity of Laurussia and Gondwana rather than the occurrence of a wide ocean separating the two palaeocontinents in Middle Devonian times. [less ▲]

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See detailAnalysis of the Llandovery in the Paraná Basin, Paraguay, boreholes 269-R1 and 269-R2
Mauller, P. M.; Pereira, E.; Grahn, Y. et al

Conference (2003)

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See detailDe l'utilité des miospores en prospection pétrolière
Steemans, Philippe ULg

Scientific conference (2003)

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See detailVila Maria Formation (Silurian, Parana Basin, Brazil): integrated radiometric and palynological age determinations
Mizusaki, A. M. P.; Melo, J. H. G.; Vignol-Lelarge, M. L. et al

in Geological Magazine (2002), 139(4), 453-463

Fresh shale samples taken from a well-known outcrop section of the Silurian Vila Maria Formation, located on the northeastern margin of the Parana Basin (Tres Barras Farm, Goias State, central-western ... [more ▼]

Fresh shale samples taken from a well-known outcrop section of the Silurian Vila Maria Formation, located on the northeastern margin of the Parana Basin (Tres Barras Farm, Goias State, central-western Brazil), have been analysed for both palynological and radiometric age determinations. The rocks yielded a fairly diverse, age-definitive cryptospore assemblage, and the same samples proved suitable for Rb-Sr analysis, despite Silurian sedimentary rocks being rarely suited to radiometric dating techniques. This study thus introduces an alternative, independent method for estimating the minimum depositional age of the Vila Maria Formation. The Rb-Sr age value has been calculated via an isochron diagram that yields 435.9 +/- 7.8 Ma. Accordingly, the latter value is interpreted as the minimum depositional age of the analysed Vila Maria strata, implying their deposition during Llandovery times. This concurs with the palynological results, which indicate an age no older than Early Silurian and, more particularly, favour an Early to Middle Llandovery (Rhuddanian-Early Aeronian) attribution. [less ▲]

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See detailPalaeozoic palynology. A special Issue in honour of Dr. Stanisla Loboziak
Steemans, Philippe ULg; Servais, T.; Streel, Maurice ULg

in Review of Palaeobotany and Palynology (2002), 118(Special Issue), 1-421

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See detailMiospore assemblages from the Silurian-Devonian boundary, in borehole A1-61, Ghadamis Basin, Libya
Rubinstein, C.; Steemans, Philippe ULg

in Review of Palaeobotany and Palynology (2002, April), 118(1-avr Sp. Iss. SI), 397-421

Well preserved and diversified miospore assemblages have been recorded from a relatively continuous sequence in borehole A1-61 which spans the Silurian-Devonian boundary in the northwestern part of the ... [more ▼]

Well preserved and diversified miospore assemblages have been recorded from a relatively continuous sequence in borehole A1-61 which spans the Silurian-Devonian boundary in the northwestern part of the Ghadamis Basin, Libya. The sequence is represented by early Devonian Lochkovian beds of the Tadrart Formation that transgress onto the Silurian Ludlow-Pridoli beds of the upper part of the 'Alternances Argilo-greseuses' Formation. The present work demonstrates a succession of miospore assemblages from closely sampled layers that have been stratigraphically dated as Ludlow-middle Pridoli and early Lochkovian by chitinozoans and acritarchs. Over 80 species of cryptospores and trilete spores have been identified. Modified detailed morphological interpretations are given. The miospore assemblages are correlated with miospore zonation schemes established for the type sequences of the Welsh Borderland, and those previously described from Libya. Early occurrences of some species as Streelispora newportensis on the western Gondwana plate, are put forward by comparison with the Old Red Sandstone continent. Phytogeographic and palaeobotanic implications based on these observations are discussed. (C) 2002 Elsevier Science B.V. All rights reserved. [less ▲]

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See detailDistribution du genre Leclercqia au Dévonien: implications paléogéographiques.
Meyer-Berthaud, Brigitte; Gerrienne, Philippe ULg; Fairon-Demaret, Muriel ULg et al

Conference (2002)

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See detailPaleozoïc Palynology: a special issue in honour of Dr. Stanislas Loboziak
Steemans, Philippe ULg; Servais, T.; Streel, Maurice ULg

Book published by Elsevier (2002)

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See detailThe Middle Devonian plant Leclercqia (Lycopsida) in eastern Gondwana
Meyer-Berthaud, B.; Fairon-Demaret, Muriel ULg; Steemans, Philippe ULg et al

Conference (2002)

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See detailGeology, palaeobotany and palynology of the Northeastern part of the Ardenne, Belgium
Steemans, Philippe ULg; Vanguestaine, M.; Gerrienne, Philippe ULg

Book published by Paleopalyno. Paléobot. Micropal. (2002)

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See detailLlandovery miospore biostratigraphy and stratigraphic evolution of the Parana Basin, Paraguay - Palaeogeographic implications
Steemans, Philippe ULg; Pereira, E.

in Bulletin de la Société Géologique de France (2002), 173(5), 407-414

The Parana Basin covers 1,600,000 km(2) including parts of southern Brazil, Paraguay, Uruguay and Argentina. It contains rocks ranging from the Ordovician to Tertiary in age. The present study is focused ... [more ▼]

The Parana Basin covers 1,600,000 km(2) including parts of southern Brazil, Paraguay, Uruguay and Argentina. It contains rocks ranging from the Ordovician to Tertiary in age. The present study is focused on the Itacurubi Group, of Llandovery age, from Paraguay. The sedimentology and palynology have been studied in three boreholes from the central part of Paraguay. The Itacurubi Group consists of the Euzebio Ayala, Vargas Pena and Cariy Formations. It corresponds to a complete transgressive - regressive cycle with maximum flooding in the Vargas Pena Formation. The sediments of the group were deposited in a glacio-marine regime and are included in the second order sequence. The palynofacies are dominated by acritarchs and chitinozoans, with miospores rare. Among the latter, cryptospores are most abundant and trilete spores very rare. The miospore assemblages are typical of the Llandovery. The presence of Laevolancis divellomedia and the successive first occurrence of the trilete spore genus Ambitisporites, followed by Archaeozonotriletes, allow the recognition of three biozones : divellomedia I, divellomedia II and chulus-nanus. Correlations between the three boreholes based on miospore biostratigraphy and sequence stratigraphy techniques are similar. The miospore assemblages have important palaeogeographic implications: (1) Ordovician / Silurian miospore assemblages, identified in South America are similar to those described in palaeogeographically distinct regions such as China, UK, Belgium, USA etc. This suggests that the phytogeographical differentiation proposed by Gray et al. [1992], with a Malvinokaffric Realm characterised by smooth tetrads and an extra-Malvinokaffric Realm characterised by ornamented tetrads, has to be reconsidered. Clearly, the same miospores are recovered from both regions, no matter if they are close to the palaeo-equator or the palaeo-pole, as is the case in Paraguay. These findings suggest that the same vegetation could survive under various climates. (2) In theory, large oceans could be impassable geographic barriers for land plant miospores larger than 25 mum in diameter. As similar miospore assemblages occur, around the Ordovician - Silurian boundary, on the Gondwana, Avalonia and Laurentia plates, it seems likely that these palaeo-continental plates were in close proximity permitting the expansion of the vegetation through these continents. Therefore, palaeogeographic reconstructions with narrow oceans between the continents better explain early miospore biogeographies in early Silurian times. (3) Maps produced by Dalziel et al. [1994] better explain the diachronism of trilete spore first appearances Hirnantian in Turkey, Rhuddanian in Saudi Arabia, early Aeronian in Libya, late Aeronian in Paraguay, latest Aeronian in UK, and possibly Telychian in USA. (4) The Baltica plate could possibly have been isolated by a geographic barrier during the Ashgill and the Llandovery, as only simple naked tetrads are known from that plate. The first appearance of the trilete spores in Gotland during the early Wenlock could correspond to the end of this geographic isolation. This apparent isolation of the Baltica plate could be due to a lack of data. [less ▲]

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See detailAn Early Devonian flora, including Cooksonia from the Paraná Basin (Brazil)
Gerrienne, Philippe ULg; Bergamaschi, S.; Pereira, E. et al

in Review of Palaeobotany and Palynology (2001), 116

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