The Experts below are selected from a list of 261 Experts worldwide ranked by ideXlab platform
D K Wright - One of the best experts on this subject based on the ideXlab platform.
-
chemostratigraphy a method to improve interwell correlation in barren sequences a case study using onshore duckmantian Stephanian sequences west midlands u k
Sedimentary Geology, 1999Co-Authors: T J Pearce, B M Besly, David Wray, D K WrightAbstract:Abstract Chemostratigraphy has been applied to onshore Duckmantian/Stephanian successions encountered in outcrop and penetrated by two boreholes from the West Midlands (U.K.). These successions represent the onshore equivalents of the `Barren Red Measures' which are important hydrocarbon-bearing sequences in the Southern North Sea. Much is known about the onshore successions in terms of sedimentology, mineralogy and provenance and thus they provide the ideal test for the validity of chemostratigraphy as a stratigraphic tool. Reliable inorganic geochemical data have been acquired from geochemical analyses of core, sidewall core and cuttings samples, with 19 elements being determined. Stratigraphic variations in elemental concentrations are compared with known variations in the mineralogical data. The established lithostratigraphic units of the Duckmantian/Stephanian intervals can also be recognized from the geochemical data and by using these data can be subdivided further. This results in an independent chemostratigraphic correlation being established for the two boreholes, which has been assessed statistically by discriminant function analysis. From the geochemical and mineralogical data, distinct changes in provenance are identified within the Upper Carboniferous successions. The sediments of the Coal Measures were derived from a north westerly and westerly source (?Caledonian), whereas the Etruria Formation sediments came from the Wales Brabant Massif, the sediments having mixed Caledonian and Cadomian characteristics. Eventually these sediments were replaced by sediments from a southern Hercynian source (Halesowen and Salop Formations).
-
Chemostratigraphy: a method to improve interwell correlation in barren sequences — a case study using onshore Duckmantian/Stephanian sequences (West Midlands, U.K.)
Sedimentary Geology, 1999Co-Authors: T J Pearce, B M Besly, David Wray, D K WrightAbstract:Abstract Chemostratigraphy has been applied to onshore Duckmantian/Stephanian successions encountered in outcrop and penetrated by two boreholes from the West Midlands (U.K.). These successions represent the onshore equivalents of the `Barren Red Measures' which are important hydrocarbon-bearing sequences in the Southern North Sea. Much is known about the onshore successions in terms of sedimentology, mineralogy and provenance and thus they provide the ideal test for the validity of chemostratigraphy as a stratigraphic tool. Reliable inorganic geochemical data have been acquired from geochemical analyses of core, sidewall core and cuttings samples, with 19 elements being determined. Stratigraphic variations in elemental concentrations are compared with known variations in the mineralogical data. The established lithostratigraphic units of the Duckmantian/Stephanian intervals can also be recognized from the geochemical data and by using these data can be subdivided further. This results in an independent chemostratigraphic correlation being established for the two boreholes, which has been assessed statistically by discriminant function analysis. From the geochemical and mineralogical data, distinct changes in provenance are identified within the Upper Carboniferous successions. The sediments of the Coal Measures were derived from a north westerly and westerly source (?Caledonian), whereas the Etruria Formation sediments came from the Wales Brabant Massif, the sediments having mixed Caledonian and Cadomian characteristics. Eventually these sediments were replaced by sediments from a southern Hercynian source (Halesowen and Salop Formations).
Robert Herman Wagner - One of the best experts on this subject based on the ideXlab platform.
-
Gondomaria grandeuryi (Zeiller) Wagner & Castro, 1998, in the context of an upper Stephanian flora from Surroca (prov. Girona, Catalonia, Spain)
2020Co-Authors: Robert Herman WagnerAbstract:A brief discussion on the general composition of the Stephanian C flora of Surroca is followed by a description of Gondomaria grandeuryi (Zeiller), a rare form of fernlike foliage of uncertain affinity. The genus Gondomaria Teixeira 1964 is discussed and comparison is made with Rhachiphyllum Kerp 1986, a 'callipterid' formgenus of Stephanian C (early Autunian) to later Autunian ages. Key words: Stephanian, Catalonia, Callipterid, Fernlike, Gondomaria.
-
proposal for the recognition of a saberian substage in the mid Stephanian west european chronostratigraphic scheme
2014Co-Authors: John A Knight, Robert Herman WagnerAbstract:A proposal by WAGNER & ALVAREZ-VAZQUEZ (2010) to recognise a Saberian Regional Substage to follow upon Barruelian is now formalised with reference to a boundary stratotype in the Sabero Coalfield (Leon), NW Spain. A brief historical perspective on the Stephanian substages (formerly stages) confirms the inadequacy of the classical A, B and C subdivision recognised in the intramontane basins of the Massif Central, France. The lower Stephanian succession in the Cantabrian Mountians, NW Spain, where it is in continuity with the highest Westphalian and shows both marine and terrestrial facies, has already provided suitable stratotypes for the Cantabrian and Barruelian substages. A Barruelian–Stephanian B boundary was recognised in the Sabero Coalfield, NW Spain, in correlation with the putative Stephanian A–B boundary identified in the Carmaux Coalfield, south-central France. This boundary lies below the base of type Stephanian B as defined in the Saint Etienne Basin. A Saberian Substage following upon Barruelian and occupying the gap below the Stephanian B at Saint Etienne is now formalised by a proposed stratotype at Sabero. Palaeobotanical analysis confirms that the Saberian is broadly equated with the Alethopteris zeilleri Megafloral Zone. The proposed stratotype is described in the context of a coastal basin with westerly onlap both within and beyond the Sabero Coalfield. Pyroclastic tonsteins in the reference Saberian succession of Sabero have permitted radiometric U-Pb dating of zircons (CATIMS) from two bands at around 302 Ma. A preliminary account of the absolute age analysis is given.
-
The Carboniferous floras of the Iberian Peninsula: A synthesis with geological connotations
Review of Palaeobotany and Palynology, 2010Co-Authors: Robert Herman Wagner, Carmen Álvarez-vázquezAbstract:Abstract A general review is presented of the Carboniferous floral records in the Iberian Peninsula in the context of the geological history and distribution of the different basins. Mississippian floras are found in Sierra Morena, where major strike-slip faults brought in terranes of diverse provenance. Lower Pennsylvanian floras are represented in the Penarroya–Belmez–Espiel (Cordoba) and Villanueva del Rio y Minas (Sevilla) coalfields of SW Spain (also strike-slip controlled), at La Camocha, near Gijon (Asturias), and in other parts of northern Spain. Middle Pennsylvanian is represented near Oporto, but more completely in the Central Asturian Coalfield, as well as other, more limited localities in NW Spain and the Pyrenees. Upper Pennsylvanian (Stephanian Stage–Cantabrian to Stephanian B substages) floras are splendidly represented in NW Spain. Uppermost Pennsylvanian (Stephanian C–Autunian) floras are present in the strike-slip controlled Douro and Bucaco basins of North Portugal, the Pyrenees, Central Spain (Ciudad Real, Guadalajara, Zaragoza), and SW Spain (Guadalcanal and Valdeviar in Sevilla province). A complete succession of megafloral zones is presented. This includes a new Annularia spicata Zone at the top of the Pennsylvanian (equivalent to middle to upper Autunian which has been often attributed to the Lower Permian). The information is summarised in charts compiled from a selection of the most significant species. A number of floral elements are illustrated including the zonal indices. Brief taxonomic comments are provided in the Appendix.
-
gondomaria grandeuryi zeiller wagner castro 1998 in the context of an upper Stephanian flora from surroca prov girona catalonia spain
Treballs del Museu de Geologia de Barcelona, 2004Co-Authors: Robert Herman WagnerAbstract:A brief discussion on the general composition of the Stephanian C flora of Surroca is followed by a description of Gondomaria grandeuryi (Zeiller), a rare form of fernlike foliage of uncertain affinity. The genus Gondomaria Teixeira 1964 is discussed and comparison is made with Rhachiphyllum Kerp 1986, a 'callipterid' formgenus of Stephanian C (early Autunian) to later Autunian ages. Key words: Stephanian, Catalonia, Callipterid, Fernlike, Gondomaria.
Hans Kerp - One of the best experts on this subject based on the ideXlab platform.
-
Aromatized arborane/fernane hydrocarbons as biomarkers for cordaites
Naturwissenschaften, 2006Co-Authors: Stefan Auras, Volker Wilde, Kay Scheffler, Stephan Hoernes, Hans Kerp, Wilhelm PüttmannAbstract:Previous palaeobotanical and palynological studies on coals from Euramerican Pennsylvanian (≡ Late Carboniferous) coal basins indicate a major change in coal-swamp floras, especially at the Westphalian–Stephanian (≈Kasimovian–Gzhelian, according to Geological Time Scale 2004) boundary. A flora dominated by arborescent lycophytes was replaced by a vegetation dominated by marattialean tree ferns in various Euramerican coal basins. Earlier combined palynological and organic geochemical studies on Westphalian/Stephanian coals and shales from the Saar-Nahe Basin (Germany) revealed that the distribution of aromatized arborane/fernane hydrocarbons in solvent extracts reflects the increasing importance of seed plants, especially cordaites (extinct group of gymnosperms), conifers and pteridosperms. However, the biological source of the precursor molecules could not be specified. To clarify if the arborane/fernane derivatives MATH, MAPH, DAPH 1, and DAPH 2 in Westphalian/Stephanian coals can be assigned to one of the three potential source plant groups, we analyzed coals, sediments and fossil plant remains from different Euramerican locations with respect to their biomarker composition and stable carbon isotopic composition. Thereby, stable carbon isotopic ratios showed only insignificant variations between Westphalian and Stephanian samples and proved to be an unsuitable tool to describe floral changes during the Westphalian/Stephanian of the Saar-Nahe Basin. In contrast, we were able to show for the first time that MATH, MAPH, DAPH 1 and DAPH 2 are prominent constituents only in extracts of cordaitean macrofossils and can therefore be regarded as biomarkers for this group of gymnosperms.
-
Epidermal anatomy of Barthelopteris germarii from the Upper Carboniferous and Lower Permian of France and Germany.
American Journal of Botany, 1998Co-Authors: Michael Krings, Hans KerpAbstract:The epidermal anatomy of Barthelopteris germarii, a late Paleozoic seed fern, is described on the basis of material from the Upper Stephanian of Central France. A number of features are described for the first time for this species. Some have never been reported for late Paleozoic pteridosperms. Although our material is in most respects very similar to previously described material of B. germarii from Germany, there are also some striking differences, especially the peltate glandular trichomes that are very common in the French but completely absent in the German material. Their presence is most probably an ecological adaptation as in many modern plants. This and other epidermal and gross-morphological features (e.g., the presence of papillae on subsidiary cells of the stomata, anastomosing venation) indicate that B. germarii was well adapted to stressed conditions. Of more general interest is the preservation of the material. There appears to exist a clear relationship between the preservation of anticlinal walls and the thickness of the parenchymatic mesophyll; anticlinal walls are very well preserved where parenchyma was thin. Therefore, the absence of anticlinal walls in fossil cuticles, which has often been used as a taxonomic character, is not necessarily a primary feature. Barthelopteris Zodrow et Cleal 1993 is a monotypic genus of pteridosperm foliage, known from the Lower Stephanian (Upper Barruelian) to the Rotliegend (?Upper Carboniferous‐Lower Permian) of Germany, France, Yugoslavia, and the Iberian Peninsula; its main occurrence is in the Upper Stephanian. Barthelopteris germarii was first described by Giebel (1857) from the Stephanian C → → →
-
Climbing and scrambling growth habits: common life strategies among Late Carboniferous seed ferns*
Comptes Rendus De L Academie Des Sciences Serie Ii Fascicule A-sciences De La Terre Et Des Planetes, 1998Co-Authors: Hans Kerp, Michael KringsAbstract:Three different types of climbing organs of seed ferns are reported from the Upper Stephanian (Uppermost Carboniferous) of central France on the basis of cuticular material. These three types are climber hooks, tendrils and branched tendrils terminating in adhesive discs. All are very similar to climbing organs of modern angiosperms. These discoveries demonstrate the potential of cuticular analysis for the reconstruction of growth habits of fossil plants. Moreover, they exemplify that climbing and scrambling were common life strategies among Late Carboniferous seed ferns. The increasing proportion of climbing seed ferns in the Stephanian is interpreted as an expression of changing community structures of Late Palaeozoic coal swamp forests.
-
regular articlecuticles oflescuropteris genuinafrom the Stephanian upper carboniferous of central france evidence for a climbing growth habit
Botanical Journal of the Linnean Society, 1997Co-Authors: Michael Krings, Hans KerpAbstract:This paper provides the first description of the cuticles ofLescuropteris genuina, a pteridosperm from the Upper Stephanian of the Blanzy-Montceau Basin, Central France. The status of the genusLescuropteris, which is often compared withOdontopteris, is discussed. However, cuticles seem to justify a separate status. Of special interest is the discovery of a modified pinna terminal with well developed tendrils, providing evidence thatL. genuinahad a climbing growth habit. The ecology ofL. genuinais discussed on the basis of new information on the epidermal anatomy.
-
cuticles of lescuropteris genuina from the Stephanian upper carboniferous of central france evidence for a climbing growth habit
Botanical Journal of the Linnean Society, 1997Co-Authors: Michael Krings, Hans KerpAbstract:Abstract This paper provides the first description of the cuticles of Lescuropteris genuina , a pteridosperm from the Upper Stephanian of the Blanzy-Montceau Basin, Central France. The status of the genus Lescuropteris , which is often compared with Odontopteris , is discussed. However, cuticles seem to justify a separate status. Of special interest is the discovery of a modified pinna terminal with well developed tendrils, providing evidence that L. genuina had a climbing growth habit. The ecology of L. genuina is discussed on the basis of new information on the epidermal anatomy.
T J Pearce - One of the best experts on this subject based on the ideXlab platform.
-
chemostratigraphy a method to improve interwell correlation in barren sequences a case study using onshore duckmantian Stephanian sequences west midlands u k
Sedimentary Geology, 1999Co-Authors: T J Pearce, B M Besly, David Wray, D K WrightAbstract:Abstract Chemostratigraphy has been applied to onshore Duckmantian/Stephanian successions encountered in outcrop and penetrated by two boreholes from the West Midlands (U.K.). These successions represent the onshore equivalents of the `Barren Red Measures' which are important hydrocarbon-bearing sequences in the Southern North Sea. Much is known about the onshore successions in terms of sedimentology, mineralogy and provenance and thus they provide the ideal test for the validity of chemostratigraphy as a stratigraphic tool. Reliable inorganic geochemical data have been acquired from geochemical analyses of core, sidewall core and cuttings samples, with 19 elements being determined. Stratigraphic variations in elemental concentrations are compared with known variations in the mineralogical data. The established lithostratigraphic units of the Duckmantian/Stephanian intervals can also be recognized from the geochemical data and by using these data can be subdivided further. This results in an independent chemostratigraphic correlation being established for the two boreholes, which has been assessed statistically by discriminant function analysis. From the geochemical and mineralogical data, distinct changes in provenance are identified within the Upper Carboniferous successions. The sediments of the Coal Measures were derived from a north westerly and westerly source (?Caledonian), whereas the Etruria Formation sediments came from the Wales Brabant Massif, the sediments having mixed Caledonian and Cadomian characteristics. Eventually these sediments were replaced by sediments from a southern Hercynian source (Halesowen and Salop Formations).
-
Chemostratigraphy: a method to improve interwell correlation in barren sequences — a case study using onshore Duckmantian/Stephanian sequences (West Midlands, U.K.)
Sedimentary Geology, 1999Co-Authors: T J Pearce, B M Besly, David Wray, D K WrightAbstract:Abstract Chemostratigraphy has been applied to onshore Duckmantian/Stephanian successions encountered in outcrop and penetrated by two boreholes from the West Midlands (U.K.). These successions represent the onshore equivalents of the `Barren Red Measures' which are important hydrocarbon-bearing sequences in the Southern North Sea. Much is known about the onshore successions in terms of sedimentology, mineralogy and provenance and thus they provide the ideal test for the validity of chemostratigraphy as a stratigraphic tool. Reliable inorganic geochemical data have been acquired from geochemical analyses of core, sidewall core and cuttings samples, with 19 elements being determined. Stratigraphic variations in elemental concentrations are compared with known variations in the mineralogical data. The established lithostratigraphic units of the Duckmantian/Stephanian intervals can also be recognized from the geochemical data and by using these data can be subdivided further. This results in an independent chemostratigraphic correlation being established for the two boreholes, which has been assessed statistically by discriminant function analysis. From the geochemical and mineralogical data, distinct changes in provenance are identified within the Upper Carboniferous successions. The sediments of the Coal Measures were derived from a north westerly and westerly source (?Caledonian), whereas the Etruria Formation sediments came from the Wales Brabant Massif, the sediments having mixed Caledonian and Cadomian characteristics. Eventually these sediments were replaced by sediments from a southern Hercynian source (Halesowen and Salop Formations).
David Wray - One of the best experts on this subject based on the ideXlab platform.
-
chemostratigraphy a method to improve interwell correlation in barren sequences a case study using onshore duckmantian Stephanian sequences west midlands u k
Sedimentary Geology, 1999Co-Authors: T J Pearce, B M Besly, David Wray, D K WrightAbstract:Abstract Chemostratigraphy has been applied to onshore Duckmantian/Stephanian successions encountered in outcrop and penetrated by two boreholes from the West Midlands (U.K.). These successions represent the onshore equivalents of the `Barren Red Measures' which are important hydrocarbon-bearing sequences in the Southern North Sea. Much is known about the onshore successions in terms of sedimentology, mineralogy and provenance and thus they provide the ideal test for the validity of chemostratigraphy as a stratigraphic tool. Reliable inorganic geochemical data have been acquired from geochemical analyses of core, sidewall core and cuttings samples, with 19 elements being determined. Stratigraphic variations in elemental concentrations are compared with known variations in the mineralogical data. The established lithostratigraphic units of the Duckmantian/Stephanian intervals can also be recognized from the geochemical data and by using these data can be subdivided further. This results in an independent chemostratigraphic correlation being established for the two boreholes, which has been assessed statistically by discriminant function analysis. From the geochemical and mineralogical data, distinct changes in provenance are identified within the Upper Carboniferous successions. The sediments of the Coal Measures were derived from a north westerly and westerly source (?Caledonian), whereas the Etruria Formation sediments came from the Wales Brabant Massif, the sediments having mixed Caledonian and Cadomian characteristics. Eventually these sediments were replaced by sediments from a southern Hercynian source (Halesowen and Salop Formations).
-
Chemostratigraphy: a method to improve interwell correlation in barren sequences — a case study using onshore Duckmantian/Stephanian sequences (West Midlands, U.K.)
Sedimentary Geology, 1999Co-Authors: T J Pearce, B M Besly, David Wray, D K WrightAbstract:Abstract Chemostratigraphy has been applied to onshore Duckmantian/Stephanian successions encountered in outcrop and penetrated by two boreholes from the West Midlands (U.K.). These successions represent the onshore equivalents of the `Barren Red Measures' which are important hydrocarbon-bearing sequences in the Southern North Sea. Much is known about the onshore successions in terms of sedimentology, mineralogy and provenance and thus they provide the ideal test for the validity of chemostratigraphy as a stratigraphic tool. Reliable inorganic geochemical data have been acquired from geochemical analyses of core, sidewall core and cuttings samples, with 19 elements being determined. Stratigraphic variations in elemental concentrations are compared with known variations in the mineralogical data. The established lithostratigraphic units of the Duckmantian/Stephanian intervals can also be recognized from the geochemical data and by using these data can be subdivided further. This results in an independent chemostratigraphic correlation being established for the two boreholes, which has been assessed statistically by discriminant function analysis. From the geochemical and mineralogical data, distinct changes in provenance are identified within the Upper Carboniferous successions. The sediments of the Coal Measures were derived from a north westerly and westerly source (?Caledonian), whereas the Etruria Formation sediments came from the Wales Brabant Massif, the sediments having mixed Caledonian and Cadomian characteristics. Eventually these sediments were replaced by sediments from a southern Hercynian source (Halesowen and Salop Formations).
