|
| ||
|
|
||
Carboniferous
Kinds of Carboniferous Selected AbstractsROSS AND BUDE FORMATIONS (CARBONIFEROUS, IRELAND AND ENGLAND): REINTERPRETED AS LAKE-SHELF TURBIDITESJOURNAL OF PETROLEUM GEOLOGY, Issue 1 2004R. Higgs The Ross Formation (Namurian, Ireland) and the near-identical Bude Formation (Westphalian, England), both amply described in the literature, are used by oil companies as deep-sea-fan reservoir analogues. However, the Ross Formation is reinterpreted here, like the Bude Formation in recent publications, to be composed of river-fed turbidites deposited on the wave-influenced northern shelf of a Variscan foreland-basin lake, which also had a southern flysch trough. Key features of these formations are: (i) two classes of thin (, 0.4m) sandstone "event bed" in shale comprising (a) structureless turbidite-like beds, and (b) rippled beds with combined-flow ripples and/or hummocky cross-stratification, neither structure having previously been reported from the Ross Formation; (ii) "trademark" tabular packets (1,10 m) of amalgamated event beds which interfinger laterally with mudstones; (iii) sharp packet bases and tops; (iv) rare sinuous channel fills; and (v) rare thick (1,10m) shale units, each containing a thin (cm-dm) fossiliferous band. The fossil bands are interpreted here as maximum flooding surfaces, reflecting glacioeustatic marine incursions over the lake spill point (sill), forcing the lake to rise and to turn marine or strongly brackish; these bands define Galloway-type depositional sequences 50,100 m thick. During eustatic falls, the lake was forced down to sill level, where it perched and turned fresh (desalination). Intervals containing sandstone packets are attributed to the falling-stage and lowstand systems tracts, each packet representing a higher-order lowstand systems tract. Packets are interpreted as tongue shaped, supplied by river-fed underflows. Packet bases (sharp) represent the storm-wave-graded equilibrium shelf profile, glacioeustatically forced to its lowstand position. On this erosion surface were deposited underflow turbidites produced by floods in the catchment. Occasional catastrophic storms on the lake shaved these turbidites and interfingering fair-weather muds back down to the equilibrium level, leaving behind a subsidence-accommodated increment whose surface was sculpted by storm wind and wave currents, forming hummocks, combined-flow ripples and erosional megaflutes. Whenever a river-fed underflow accompanied one of these storms, the resulting highly erosive combined flow carved a sinuous channel on the wave-sculpted equilibrium surface. Sandstone-shale intervals separating the sandstone packets are interpreted as transgressive- and highstand systems tracts. They contain both turbidites and wave-modified turbidites (rippled beds), deposited on the out-of-equilibrium drowned shelf. A gradual rotation in sole-mark direction with time in both formations is attributed to a reversal of Coriolis deflection as the plate drifted north across the equator, causing underflows (deflected along-shelf geostrophically) to flow first NEwards and then SWwards on an inferred SE-facing shelf. The lack of evidence for emergence in the Ross and Bude Formations, in spite of the great thicknesses (460m and 1,290m, respectively) of these shallow-water deposits, is attributed to regulation of minimum water depth firstly by the lake sill blocking eustatically-forced exposure, and secondly by storm grading, preventing emergence by sedimentation. [source] AGGREGATION BEHAVIOUR IN JUVENILE MILLIPEDES FROM THE UPPER CARBONIFEROUS OF MAZON CREEK, ILLINOISPALAEONTOLOGY, Issue 4 2006HEATHER M. WILSON Abstract:, Two ironstone nodules are described from the Braidwood Biota of the Upper Carboniferous Mazon Creek Lagerstätte, Illinois, each preserving numerous juvenile millipedes referred to Euphoberia sp. The millipedes belong to different stadia, as evidenced by segment number, but are similar in size so probably nearly the same age. These juvenile euphoberiids differ from adults in having shorter pleurotergal spines, a reduced number of ocelli and a series of reduced, apodous trunk rings posteriorly. These nodules provide the first evidence of aggregation behaviour in Palaeozoic millipedes. Aggregation in juvenile euphoberiids is hypothesized to serve as a defence mechanism, compensating for the reduced length of their pleurotergal spines relative to adults, possibly through a collective chemical defence. [source] A new platysomid from the Upper Carboniferous of Kansas (USA) and remarks on the systematics of deep-bodied lower actinopterygiansACTA ZOOLOGICA, Issue 2009Kathryn E. Mickle Abstract Scales and presumptive tooth plates from deep-bodied platysomid actinopterygians have previously been reported from the Lower Permian of Kansas (USA), but until now, an articulated specimen from this state has not been recovered. The first articulated deep-bodied platysomid fish from the Upper Carboniferous of Kansas is described herein. This specimen is compared to other known species from the genus Platysomus, with special attention paid to the North American taxa. The cranial osteology of this new specimen is closest to Platysomus schultzei from the Upper Carboniferous of New Mexico. The newly described platysomid species highlights the need for a revision of the fish included within the genus Platysomus. [source] A juvenile Early Carboniferous (Viséan) coelacanth from Rösenbeck (Rhenish Mountains, Germany) with derived postcranial charactersFOSSIL RECORD-MITTEILUNGEN AUS DEM MUSEUM FUER NATURKUNDE, Issue 2 2010Florian Witzmann Abstract A small coelacanth specimen of Viséan age from a newly described locality near Rösenbeck at the northern margin of the Rhenish Mountains (North Rhine-Westphalia, Germany) is described. The head and pectoral girdle are not preserved, however, the specimen can be distinguished from all other known Carboniferous coelacanths by derived characters of the articulated postcranial skeleton. Derived characters include: (1) The slender first and second dorsal fins that carry only seven to eight and six fin rays, respectively. (2) Both the pelvic and anal fin have a broad base and are unusually weakly lobed. (3) The fin rays of the second dorsal fin are much more robust than those of the first dorsal fin. (4) The second dorsal and anal fins are longer than the first dorsal and pelvic fins. The Rösenbeck coelacanth is interpreted as a juvenile specimen, since the basal plates that support the fins are not ossified. (© 2010 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source] The ammonoids from the Argiles de Teguentour of Oued Temertasset (early Late Tournaisian; Mouydir, Algeria)FOSSIL RECORD-MITTEILUNGEN AUS DEM MUSEUM FUER NATURKUNDE, Issue 1 2010Dieter Korn Abstract The ammonoids from the Teguentour Shales (Tournaisian, Early Carboniferous) of Oued Temertasset (Mouydir, Algeria) are described monographically. The following new ammonoid taxa are introduced: Imitoceras dimidium n. sp., Imitoceras strictum n. sp., Triimitoceras tantulum n. sp., Acrocanites disparilis n. sp., Jdaidites cultellus n. sp., Pericyclus tortuosus n. sp., Pericyclus circulus n. sp., Pericyclus trochus n. sp., Pericyclus intercisus n. sp., Nodopericyclus n. gen., Nodopericyclus circumnodosus n. sp., Nodopericyclus deficerus n. sp., Ammonellipsites serus n. sp., Helicocyclus formosus n. sp., Helicocyclus inornatus n. sp., Helicocyclus laxaris n. sp., Ouaoufilalites creber n. sp., family Temertassetiidae n. fam., Temertassetia n. gen., Temertassetia temertassetensis n. sp., Temertassetia secunda n. sp., Temertassetia decorata n. sp., Temertassetia coarta n. sp., Jerania n. gen., Jerania jeranensis n. sp., Jerania sicilicula n. sp., Jerania pusillens n. sp., Jerania subvexa n. sp., Jerania persimilis n. sp., Kusinia n. gen., Kusinia falcifera n. sp., Bouhamedites insalahensis n. sp., Muensteroceras subparallelum n. sp., M ensteroceras multitudum n. sp., Follotites n. gen., Follotites folloti n. sp., Follotites stelus n. sp., Follotites flexus n. sp., family Rotopericyclidae n. fam., Eurites permutus n. sp., Eurites doliaris n. sp., Mouydiria n. gen., Mouydiria mouydirensis n. sp., Mouydiria scutula n. sp., Rotopericyclus kaufmanni n. sp., Rotopericyclus rathi n. sp., Rotopericyclus wendti n. sp., Rotopericyclus lubesederi n. sp., subfamily Dzhaprakoceratinae n. subfam., Dzhaprakoceras punctum n. sp., Dzhaprakoceras amplum n. sp., Dzhaprakoceras vergum n. sp., Dzhaprakoceras biconvexum n. sp., Progoniatitinae n. subfam., Progoniatites uncus n. sp., Progoniatites pilus n. sp., Progoniatites paenacutus n. sp., Progoniatites globulus n. sp., Habadraitinae n. subfam., Habadraites n. gen., Habadraites weyeri n. sp., Habadraites supralatus n. sp., Primogoniatites n. gen., Primogoniatites fundator n. sp., Antegoniatitinae n. subfam., Antegoniatites n. gen., and Antegoniatites anticiparis n. sp.. The ammonoids occur in three successive assemblages and are the richest ammonoid faunas of the time interval worldwide. (© 2010 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source] The ammonoids from the Dalle à Merocanites of Timimoun (Late Tournaisian,Early Viséan; Gourara, Algeria)FOSSIL RECORD-MITTEILUNGEN AUS DEM MUSEUM FUER NATURKUNDE, Issue 1 2010Volker Ebbighausen Abstract The ammonoids from the Early Carboniferous (Mississippian) Dalle à Merocanites of Timimoun (Gourara, Algeria) are described. The following new ammonoid taxa are introduced: subfamily Hammatocyclinae n. subfam., Hammatocyclus pollex n. sp., Hammatocyclus corrugatus n. sp., Neopericyclus arenosus n. sp., Ammonellipsites pareyni n. sp., Ammonellipsites menchikoffi n. sp., Ammonellipsites conradae n. sp., Muensteroceras fabrei n. sp., Eurites commutatus n. sp., Eurites pondus n. sp., subfamily Trimorphoceratinae n. subfam., Trimorphoceras n. gen., Trimorphoceras crassilens n. sp., Trimorphoceras absolutum n. sp., Trimorphoceras molestum n. sp., Obturgites n. gen., Obturgites polysarcus n. sp., Obturgites oligosarcus n. sp., Dzhaprakoceras dzhazairense n. sp., and Merocanites merocanites n. sp. These species occur in one very prolific horizon and can be attributed to the North African Ammonellipsites - Merocanites Assemblage (Fascipericyclus - Ammonellipsites Genus Zone; Late Tournaisian to Early Viséan). They represent one of the most diverse ammonoid faunas known from this time interval. (© 2010 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source] Ammonoids from the Dalle des Iridet of the Mouydir and Ahnet (Central Sahara) and the Formation d'Hassi Sguilma of the Saoura Valley (Late Tournaisian,Early Viséan; Algeria)FOSSIL RECORD-MITTEILUNGEN AUS DEM MUSEUM FUER NATURKUNDE, Issue 1 2010Dieter Korn Abstract Four ammonoid species are described from the Early Carboniferous (Mississippian) Iridet Formation of the Ahnet and Mouydir (Central Sahara, Algeria); three of which are new: Eurites temertassetensis n. sp., Trimorphoceras teguentourense n. sp., and Trimorphoceras azzelmattiense n. sp. The species can be attributed to the North African Ammonellipsites - Merocanites Assemblage (Fascipericyclus - Ammonellipsites Genus Zone; Late Tournaisian to Early Viséan). Additionally, the two new species Ammonellipsites sguilmensis n. sp. and Muensteroceras beniabbesense n. sp. are described from the time equivalent Hassi Sguilma Formation of the Saoura Valley (north-western Algeria). (© 2010 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source] A Late Carboniferous fossil scorpion from the Piesberg, near Osnabrück, GermanyFOSSIL RECORD-MITTEILUNGEN AUS DEM MUSEUM FUER NATURKUNDE, Issue 1 2008Jason A. Dunlop Abstract A new fossil scorpion , only the second from the Late Carboniferous (Pennsylvanian) of western Germany , is described from the Westphalian D of the Piesberg near Osnabrück, Germany. This slender and rather gracile specimen is very closely related to the stratigraphically contemporary Eoscorpius carbonarius Meek & Worthern, 1868 from Mazon Creek, Illinois, USA and is here assigned to E. cf. carbonarius. A precise placement is hindered by the need for revision of the late Carboniferous scorpion fauna. (© 2008 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source] Palaeozoic tropical rainforests and their effect on global climates: is the past the key to the present?GEOBIOLOGY, Issue 1 2005CHRISTOPHER J. CLEAL ABSTRACT Wetland forests, known as coal forests, extended over large areas of the palaeotropics during the Late Carboniferous and the Permian Periods. They were initiated during the Serpukhovian Age as a response to lowering sea levels having exposed large areas of continental shelf. They expanded dramatically during the late Bashkirian Age, but then contracted by over one-half during the Kasimovian Age. The estimated loss of carbon sink probably resulted in an annual increase in atmospheric CO2 of about 2,5 ppm, and coincided with clear evidence of global warming in both the northern and southern high latitudes. A return to cooler conditions in very Early Permian times coincided with an expansion of the palaeotropical coal forests in the Far East, but this was short-lived and most of the rest of the Permian was a time of global warming. The Palaeozoic evidence clearly confirms that there is a correlation between levels of atmospheric CO2 and global climates. However, care must be taken in extrapolating this evidence to the present-day tropical forests, which do not act as a comparable unsaturated carbon sink. [source] Palynological evidence for Pennsylvanian (Late Carboniferous) vegetation change in the Sydney Coalfield, eastern CanadaGEOLOGICAL JOURNAL, Issue 4 2010Tatyana K. Dimitrova Abstract The palynology of clastic samples from seven stratigraphical levels in the late Moscovian Sydney Mines Formation, exposed along the shore at Bras d'Or, Nova Scotia, has been investigated. Most of the samples were from roof shales of major coals; the one sample that was not yielded a much higher proportion of pollen derived from extra-basinal vegetation. The four stratigraphically lower roof shale samples yielded essentially similar palynological spectra, with 39,±,4% lycophytes, 9,±,4% sphenophylls, 23,±,4% tree-ferns, 12,±,4% other ferns and 5,±,3% cordaites. The palynology of the upper part of the investigated succession suggests a shift in vegetation towards one favouring more marattialean tree-ferns, cordaites and conifers, and fewer lycophytes. This correlates with changes in drainage patterns as the alluvial plain migrated seawards and thus changed water tables. No evidence was found to suggest significant climate change at this time. Copyright © 2009 John Wiley & Sons, Ltd. [source] From the intra-desert ridges to the marine carbonate island chain: middle to late Permian (Upper Rotliegend,Lower Zechstein) of the Wolsztyn,Pogorzela high, west PolandGEOLOGICAL JOURNAL, Issue 2-3 2010Hubert Kiersnowski Abstract The tectonic Wolsztyn,Pogorzela palaeo-High (WPH) is the south-eastern termination of the Brandenburg,Wolsztyn High (western Poland), which during Late Permian times was an intra-basin ridge surrounded by Upper Rotliegend sedimentary basins within the Southern Permian Basin. The geological history and structural framework of the WPH are complex. The High belongs to the Variscan Externides, consisting at present of strongly folded, faulted and eroded Viséan to Namurian flysch deposits capped by a thick cover of Upper Carboniferous,Lower Permian volcanic rocks. This sedimentary-volcanic complex was strongly fragmented and vertically differentiated by tectonic movements and subsequently eroded, resulting in the deposition of coarse clastics surrounding uplifted tectonic blocks. During late Rotliegend time, arid climatic conditions significantly influenced occurrences of specific facies assemblages: alluvial, fluvial, aeolian and playa. Sedimentological study helped to recognize the interplay of tectonic and palaeoclimatic factors and to understand the phenomenon of aeolian sandstones interbedded with coarse deposits of alluvial cones close to fault scarps. Subsequent tectonic and possible thermal subsidence of the studied area was synchronous with inundation by the Zechstein Sea. The rapid inundation process allowed for the preservation of an almost perfectly protected Uppermost Rotliegend landscape. Based on 3D seismic data from the base Zechstein reflector, a reconstruction of Rotliegend palaeogeomorphology was carried out, which shows examples of tectonic rejuvenation of particular tectonic blocks within the WPH area before inundation by the Zechstein Sea. The inundation led to the deposition of the marine Kupferschiefer Shale followed by the Zechstein Limestone. In the deeper parts of the basin the latter is developed in thin basinal facies: in shallow parts (e.g. uplifted tectonic blocks forming in some cases islands), carbonate buildups were formed. The remarkable thickness of those buildups (bryozoan reefs) is interpreted as due to stable tectonic subsidence together with a rise of sea level. A detailed study of carbonate buildups has showed that their internal structure reflects changes in shallow marine environments and even emersion events, caused by sea-level oscillations and tectonic movements of the reef substrate. Copyright © 2010 John Wiley & Sons, Ltd. [source] A high-resolution relative time scale for the Viséan Stage (Carboniferous) of the Kulm Basin (Rhenish Mountains, Germany)GEOLOGICAL JOURNAL, Issue 3 2009Dieter Korn Abstract The Viséan (Carboniferous) sedimentary succession of the basinal Kulm facies (Rhenish Mountains) was investigated in detail in order to achieve a high-resolution stratigraphic subdivision and correlation. Additionally, the ranges of fossil index taxa (ammonoids), fossil marker beds, volcaniclastic horizons and sedimentary features (e.g. colour changes) were integrated in the correlation. As a result, a comprehensive database was compiled, which contains 190 stratigraphic events of the Viséan interval of this area. Several sections are almost completely composed of shales, which are regarded to represent a slow but constant basinal background sedimentation of the Kulm facies. The thickness of lithological homogeneous sections thus indicates an approximately linear record of time and the average thicknesses of biozones and positions of stratigraphic events can easily be calculated from the compiled database. The result is an approximately time-linear biostratigraphic scale for the Viséan Stage of the Kulm Basin. Given a numerical length of the Viséan Stage of ca. 19,Ma, 190 stratigraphic events give a mean resolution of 100,000 years. This is unique in Palaeozoic stratigraphy. Copyright © 2008 John Wiley & Sons, Ltd. [source] Early Carboniferous (Mississippian) calciturbidites in the northern Rhenish Mountains (Germany)GEOLOGICAL JOURNAL, Issue 2-3 2008D. Korn Abstract Viséan calciturbidites occur in two separate turbidite sequences at the northern margin of the Rhenish Mountains: (1) the Herdringen Sequence (Becke-Oese, Retringen and Herdringen formations), and (2) the Hellefeld Sequence (Hellefeld, Linnepe and Wennemen formations). Both sequences show temporal fluctuations in the carbonate content, which can be related to global eustatic fluctuations. Two peaks of carbonate sedimentation which occurred during lowstands in the Holkerian to early Asbian and in the Brigantian are interrupted by a late Asbian decline of carbonate deposition during a transgressive interval. Patterns of bed thickness and carbonate content in the Herdringen Sequence indicate a sediment source to the north; it shifted during the Late Viséan from the northeast to the northwest. Coeval sediments in the Hellefeld Sequence were derived from a source to the southeast. Detailed analyses of Asbian sections show the high potential for fine-scaled correlation. Copyright © 2007 John Wiley & Sons, Ltd. [source] Lower Carboniferous peritidal carbonates and associated evaporites adjacent to the Leinster Massif, southeast Irish MidlandsGEOLOGICAL JOURNAL, Issue 2 2005Zsolt R. Nagy Abstract Analysis of a 275,m-thick section in the Milford Borehole, GSI-91-25, from County Carlow, Ireland, has revealed an unusual sequence of shallow subtidal, peritidal and sabkha facies in rocks of mid?-late Chadian to late Holkerian (Viséan, Lower Carboniferous) age. Sedimentation occurred on an inner ramp setting, adjacent to the Leinster Massif. The lower part of the sequence (late Chadian age) above the basal subtidal bioclastic unit is dominated by oolite sand facies associations. These include a lower regressive dolomitized, oolitic peloidal mobile shoal, and an upper, probably transgressive, backshoal oolite sand. A 68,m-thick, well-developed peritidal sequence is present between the oolitic intervals. These rocks consist of alternating stromatolitic fenestral mudstone, dolomite and organic shale, with evaporite pseudomorphs and subaerial exposure horizons containing pedogenic features. In the succeeding Arundian,Holkerian strata, transgressive,regressive carbonate units are recognized. These comprise high-energy, backshoal subtidal cycles of argillaceous skeletal packstones, bioclastic grainstones with minor oolites and algal wackestones to grainstones and infrequent algal stromatolite horizons. The study recognizes for the first time the peritidal and sabkha deposits in Chadian rocks adjacent to the Leinster Massif in the eastern Irish Midlands. These strata appear to be coeval with similar evaporite-bearing rocks in County Wexford that are developed on the southern margin of this landmass, and similar depositional facies exist further to the east in the South Wales Platform, south of St. George's Land, and in Belgium, south of the Brabant Massif. The presence of evaporites in the peritidal facies suggests that dense brines may have formed adjacent to the Leinster Massif. These fluids may have been involved in regional dolomitization of Chadian and possibly underlying Courceyan strata. They may also have been a source of high salinity fluids associated with nearby base-metal sulphide deposits. Copyright © 2005 John Wiley & Sons, Ltd. [source] Fluid evolution in base-metal sulphide mineral deposits in the metamorphic basement rocks of southwest Scotland and Northern IrelandGEOLOGICAL JOURNAL, Issue 1 2005Martin Baron Abstract The Dalradian and Ordovician,Silurian metamorphic basement rocks of southwest Scotland and Northern Ireland host a number of base-metal sulphide-bearing vein deposits associated with kilometre-scale fracture systems. Fluid inclusion microthermometric analysis reveals two distinct fluid types are present at more than half of these deposits. The first is an H2O,CO2,salt fluid, which was probably derived from devolatilization reactions during Caledonian metamorphism. This stage of mineralization in Dalradian rocks was associated with base-metal deposition and occurred at temperatures between 220 and 360°C and pressures of between 1.6 and 1.9,kbar. Caledonian mineralization in Ordovician,Silurian metamorphic rocks occurred at temperatures between 300 and 360°C and pressures between 0.6 and 1.9,kbar. A later, probably Carboniferous, stage of mineralization was associated with base-metal sulphide deposition and involved a low to moderate temperature (Th 70 to 240°C), low to moderate salinity (0 to 20,wt% NaCl eq.), H2O,salt fluid. The presence of both fluids at many of the deposits shows that the fractures hosting the deposits acted as long-term controls for fluid migration and the location of Caledonian metalliferous fluids as well as Carboniferous metalliferous fluids. Copyright © 2004 John Wiley & Sons, Ltd. [source] Tectono-sedimentary evolution of the northernmost margin of the NE German Basin between uppermost Carboniferous and Late Permian (Rotliegend)GEOLOGICAL JOURNAL, Issue 1 2001H. Rieke Abstract The tectono-sedimentary evolution of the Rotliegend deposits of the northernmost margin of NE German Basin (NEGB) has been analysed on the basis of detailed sedimentary logs of 300,m of core material together with the re-evaluation of 600,km of seismic lines. Three distinct phases were recognized. During the initial Phase I, basin geometry was largely controlled by normal faulting related to deep-seated ductile shearing leading to a strong asymmetric shape, with a steep fault-controlled eastern margin and a gently, dipping western margin. The results of forward modelling along a cross-section fit the basin geometry in width and depth and reveal a footwall uplift of c. 1000,m. Adjacent to the steep faults, local sedimentation of Lithofacies Type I was confined to non-cohesive debris flow-dominated alluvial fans, whereas the gently dipping western margin was dominated by alluvial-cone sedimentation. During the post-extensional period (Phase II), cooling of the lithosphere generated additional accommodation space. The sediments of Lithofacies Type II, comprising mainly clast-supported conglomerates, are interpreted as braided ephemeral stream flow-surge deposits. Tectonic quiescence and an increase in flood events resulting from wetter climate led to progradation of this facies over the entire region. At the end of this period, the accommodation space was almost completely filled resulting in a level topography. Phase III was controlled by the thermal-induced subsidence of the southerly located NEGB in post-Illawarra times. The formerly isolated region tilted towards the SW, thus forming the northern margin of the NEGB during uppermost Havel and Elbe Subgroup times. The sediments of Lithofacies Type III were divided into a marginal sandstone-dominated environment and a finer-grained facies towards the SW. The former consists of poorly-sorted coarse-grained sandstones of a proximal and medial ephemeral stream floodplain facies. The latter comprise mud flat fines and fine-grained distal ephemeral stream deposits. The end of the tectono-sedimentary evolution is marked by the basinwide Zechstein transgression. Copyright © 2001 John Wiley & Sons, Ltd. [source] Going underground: in search of Carboniferous coal forestsGEOLOGY TODAY, Issue 5 2009Howard J. Falcon-Lang The development of coal forests during the Carboniferous is one of the best-known episodes in the history of life. Although often reconstructed as steamy tropical rainforests, these ancient ecosystems were a far cry from anything we might encounter in the Amazon today. Bizarre giant club-mosses, horsetails and tree ferns were the dominant plants, not flowering trees as in modern rainforests. At their height, coal forests stretched all the way from Kansas to Kazakhstan, spanning the entire breadth of tropical Pangaea. Most of what we know of their biodiversity and ecology has been quite literally mined out of the ground through two centuries of hard labour. Without coal mining, our knowledge would be greatly impoverished. Over the past few years, we've been exploring underground coal mines in the United States, where entire forested landscapes have been preserved intact over huge areas. Never before have geologists had the opportunity to walk out through mile upon mile of fossilized forest. In this feature article, we describe some of our recent explorations and attempt to shed new light on these old fossils. [source] Provenance of Coals Recovered from the Wreck of HMAV BountyINTERNATIONAL JOURNAL OF NAUTICAL ARCHAEOLOGY, Issue 1 2008Nigel Erskine Coal samples from HMAV Bounty were analysed using standard techniques to shed light on their provenance. Petrographic analysis indicated they were Carboniferous, with high vitrinite and liptinite content and a mean random reflectance of vitrinite of 0.99%. Palynological analysis indicated the samples were derived from the Middle Coal Measures, Westphalian B. Combining coal rank (vitrinite reflectance), age, knowledge of seam distributions and coalfield history indicates the most like source to be the Durham Coalfield, possibly the Hutton or Low Main Seams. These coals were mined along the valley of the Weir in the latter part of the 18th century. © 2007 The Authors [source] Robust support for tardigrade clades and their ages from three protein-coding nuclear genesINVERTEBRATE BIOLOGY, Issue 2 2004Jerome C. Regier Abstract. Coding sequences (5,334 nt total) from elongation factor-1,, elongation factor-2, and the largest subunit of RNA polymerase II were determined for 6 species of Tardigrada, 2 of Arthropoda, and 2 of Onychophora. Parsimony and likelihood analyses of nucleotides and amino acids yielded strong support for Tardigrada and all internal nodes (i.e., 100% bootstrap support for Tardigrada, Eutardigrada, Parachela, Hypsibiidae, and Macrobiotidae). Results are in agreement with morphology and an earlier molecular study based on analysis of 18S ribosomal sequences. Divergence times have been estimated from amino acid sequence data using an empirical Bayesian statistical approach, which does not assume a strict molecular clock. Divergence time estimates are pre-Vendian for Tardigrada/Arthropoda, Vendian or earlier for Eutardigrada/Heterotardigrada, Silurian to Ordovician for Parachela/Apochela, Permian to Carboniferous for Hypsibiidae and Macrobiotidae, and Mesozoic for Isohypsibius/Thulinia (both within Hypsibiidae) and Macrobiotus/Richtersius (both within Macrobiotidae). [source] Role of southeastern Sanandaj,Sirjan Zone in the tectonic evolution of Zagros Orogenic Belt, IranISLAND ARC, Issue 4 2009Ramin Arfania Abstract Geological studies indicate that the southeastern Sanandaj,Sirjan Zone, located in the southeastern Zagros Orogenic Belt, is subdivided transversally into the Esfahan,Sirjan Block with typical Central Iranian stratigraphic features and the Shahrekord,Dehsard Terrane consisting of Paleozoic and Lower Mesozoic metamorphic rocks. The Main Deep Fault (Abadeh Fault) is a major lithospheric fault separating the two parts. The purpose of this paper is to clarify the role of the southeastern Sanandaj,Sirjan Zone in the tectonic evolution of the southeastern Zagros Orogenic Belt on the basis of geological evidence. The new model implies that Neo-Tethys 1 came into being when the Central Iran Microcontinent split from the northeastern margin of Gondwana during the Late Carboniferous to Early Permian. During the Late Triassic a new spreading ridge, Neo-Tethys 2, was created to separate the Shahrekord,Dehsard Terrane from Afro,Arabian Plate. The Zagros sedimentary basin was formed on a continental passive margin, southwest of Neo-Tethys 2. The two ophiolitic belts of Naien,Shahrebabak,Baft and Neyriz were developed to the northeast of Neo-Tethys 1 and southwest of Neo-Tethys 2 respectively, related to the sinking of the lithosphere of the Neo-Tethys 1 in the Late Cretaceous. It can be concluded that deposition of the Paleocene conglomerate on the Central Iran Microcontinent and Pliocene conglomerate in the Zagros Sedimentary Basin is directly linked to the uplift generated by collision. [source] Structure of Sumatra and its implications for the tectonic assembly of Southeast Asia and the destruction of PaleotethysISLAND ARC, Issue 1 2009Anthony J. Barber Abstract It is now generally accepted that Southeast Asia is composed of continental blocks which separated from Gondwana with the formation of oceanic crust during the Paleozoic, and were accreted to Asia in the Late Paleozoic or Early Mesozoic, with the subduction of the intervening oceanic crust. From east to west the Malay peninsula and Sumatra are composed of three continental blocks: East Malaya with a Cathaysian Permian flora and fauna; Sibumasu, including the western part of the Malay peninsula and East Sumatra, with Late Carboniferous,Early Permian ,pebbly mudstones' interpreted as glaciogenic diamictites; and West Sumatra, again with Cathaysian fauna and flora. A further unit, the Woyla nappe, is interpreted as an intraoceanic arc thrust over the West Sumatra block in the mid Cretaceous. There are varied opinions concerning the age of collision of Sibumasu with East Malaya and the destruction of Paleotethys. In Thailand, radiolarites have been used as evidence that Paleotethys survived until after the Middle Triassic. In the Malay peninsula, structural evidence and the ages of granitic intrusions are used to support a Middle Permian to Early Triassic age for the destruction of Paleotethys. It is suggested that the West Sumatra block was derived from Cathaysia and emplaced against the western margin of Sibumasu by dextral transcurrent faulting along a zone of high deformation, the Medial Sumatra Tectonic Zone. These structural units can be traced northwards in Southeast Asia. The East Malaya block is considered to be part of the Indochina block, Sibumasu can be traced through Thailand into southern China, the Medial Sumatra Tectonic Zone is correlated with the Mogok Belt of Myanmar, the West Burma block is the extension of the West Sumatra block, from which it was separated by the formation of the Andaman Sea in the Miocene, and the Woyla nappe is correlated with the Mawgyi nappe of Myanmar. [source] The Cathaysia Flora and the Mixed Late Permian Cathaysian-Angaran Floras in East AsiaJOURNAL OF INTEGRATIVE PLANT BIOLOGY, Issue 4 2006Ke-Qin Sun Abstract The Cathaysia flora, one of the most prominent floras of the Carboniferous and Permian, was mainly distributed in East Asia and was characterized by numerous endemic elements. China is one of the most important localities of the Cathaysia flora and it is also the center of origin of this flora. This paper reviews and discusses the characteristics of the Cathaysia flora and the biogeographically mixed Permian Cathaysian-Angaran floras of East Asia. In addition, the formative mechanism of the mixed Permian floras is also discussed. (Managing editor: Ya-Qin) [source] P,T,X controls on phase stability and composition in LTMP metabasite rocks , a thermodynamic evaluationJOURNAL OF METAMORPHIC GEOLOGY, Issue 5 2010G. PHILLIPS Abstract The stability of pumpellyite + actinolite or riebeckite + epidote + hematite (with chlorite, albite, titanite, quartz and H2O in excess) mineral assemblages in LTMP metabasite rocks is strongly dependent on bulk composition. By using a thermodynamic approach (THERMOCALC), the importance of CaO and Fe2O3 bulk contents on the stability of these phases is illustrated using P,T and P,X phase diagrams. This approach allowed P,T conditions of ,4.0 kbar and ,260 °C to be calculated for the growth of pumpellyite + actinolite or riebeckite + epidote + hematite assemblages in rocks containing variable bulk CaO and Fe2O3 contents. These rocks form part of an accretionary wedge that developed along the east Australian margin during the Carboniferous,Triassic New England Orogen. P,T and P,X diagrams show that sodic amphibole, epidote and hematite will grow at these conditions in Fe2O3 -saturated (6.16 wt%) metabasic rocks, whereas actinolite and pumpellyite will be stable in CaO-rich (10.30 wt%) rocks. With intermediate Fe2O3 (,3.50 wt%) and CaO (,8.30 wt%) contents, sodic amphibole, actinolite and epidote can coexist at these P,T conditions. For Fe2O3 -saturated rocks, compositional isopleths for sodic amphibole (Al3+ and Fe3+ on the M2 site), epidote (Fe3+/Fe3+ + Al3+) and chlorite (Fe2+/Fe2+ + Mg) were calculated to evaluate the efficiency of these cation exchanges as thermobarometers in LTMP metabasic rocks. Based on these calculations, it is shown that Al3+ in sodic amphibole and epidote is an excellent barometer in chlorite, albite, hematite, quartz and titanite buffered assemblages. The effectiveness of these barometers decreases with the breakdown of albite. In higher- P stability fields where albite is absent, Fe2+ -Mg ratios in chlorite may be dependent on pressure. The Fe3+/Al and Fe2+/Mg ratios in epidote and chlorite are reliable thermometers in actinolite, epidote, chlorite, albite, quartz, hematite and titanite buffered assemblages. [source] Metastable persistence of pelitic metamorphic assemblages at the root of a Cretaceous magmatic arc , Fiordland, New ZealandJOURNAL OF METAMORPHIC GEOLOGY, Issue 3 2009N. R. DACZKO Abstract Four aluminosilicate-bearing, amphibolite facies pelitic schists sampled from the root of the long-lived eastern Gondwana continental magmatic arc now exposed in southwest Fiordland, New Zealand, record remarkably different P,T,t histories. The four samples were collected from within 20 km of each other within the Fanny Bay Group and Deep Cove Gneiss near Dusky Sound. Integrated petrography, mineral chemistry, mineral equilibria modelling and in situ electron microprobe chemical dating of monazite shows that the sample of the Fanny Bay Group south of the Dusky Fault records a Carboniferous history with peak conditions of 4,4.5 kbar at 570,590 °C, while one sample of the Deep Cove Gneiss from Long Island records a Cretaceous history with apparent peak conditions of 7.5 kbar at 650 °C. Two other samples of the Deep Cove Gneiss from Resolution Island record mixed Carboniferous and Cretaceous histories with apparent peak conditions of 7 kbar at 650 °C and 3,7 kbar at 640,720 °C. The metapelitic schists on Resolution Island were intruded by arc magmas including the voluminous high- P Western Fiordland Orthogneiss, yet they lack mineralogical evidence of the Cretaceous high- P (>12 kbar) event. Analysis of water isopleths in a model system shows that the amount of water accommodated in the rock mineral assemblage increases with pressure. With the exhaustion of all free water, and without the addition of external water, these rocks persisted metastably within the deep arc during the high- P event. The emplacement of large volumes of diorite (i.e. the Western Fiordland Orthogneiss) into the root of the Early Cretaceous continental magmatic arc did not lead to regional granulite facies metamorphism of the country rock schists, as large volumes of amphibolite facies rock metamorphosed under medium- P conditions persisted metastably in the deep arc crust. [source] Contrasting textural record of two distinct metamorphic events of similar P,T conditions and different durationsJOURNAL OF METAMORPHIC GEOLOGY, Issue 8 2005O. LEXA Abstract A structural, metamorphic and geochronological study of the Staré M,sto belt implies the existence of two distinct metamorphic events of similar peak P,T conditions (700,800 °C, 8,10 kbar) during the Cambro-Ordovician and the Carboniferous tectonometamorphic events. The hypothesis of two distinct periods of metamorphism was suggested on the basis of structural discordance between an undoubtedly Carboniferous granodiorite sill intrusion and earlier Cambro-Ordovician fabrics of a banded amphibolite complex. The analysis of crystal size distribution (CSD) shows high nucleation density (N0) and low average growth rate (Gt) for Carboniferous mylonitic metagabbros and mylonitic granodiorites. The parameter N0 decreases whereas the quantity Gt increases towards higher temperatures progressively approaching the values obtained from the Cambro-Ordovician banded amphibolite complex. The spatial distribution of amphibole and plagioclase shows intense mechanical mixing for lower-temperature mylonitic metagabbros. In high-temperature mylonites a strong aggregate distribution is developed. Cambro-Ordovician amphibolites unaffected by Carboniferous deformation show a regular to anticlustered spatial distribution resulting from heterogeneous nucleation of individual phases. This pattern, together with CSD, was subsequently modified by the grain growth and textural equilibration controlled by diffusive mass transfer during Carboniferous metamorphism. The differences between the observed textures of the amphibolites are interpreted to be a consequence of the different durations of the Carboniferous and Cambro-Ordovician thermal events. [source] OIL-PRONE LOWER CARBONIFEROUS COALS IN THE NORWEGIAN BARENTS SEA: IMPLICATIONS FOR A PALAEOZOIC PETROLEUM SYSTEMJOURNAL OF PETROLEUM GEOLOGY, Issue 2 2010J.H. Van Koeverden In this study, we assess the oil generation potential of Lower Carboniferous, liptinite-rich coals in the Tettegras Formation on the Finnmark Platform, southern Norwegian Barents Sea. Oil from these coals has been expelled into intercalated sandstones. The coals may have contributed to petroleum recorded in well 7128/4,1 on the Finnmark Platform and may constitute a new Palaeozoic source rock in the Barents Sea. The Tettegras Formation coals contain up to 80 vol.% liptinite (mineral matter free base) and have low oxygen indices. Hydrogen indices up to 367 mg HC/g TOC indicate liquid hydrocarbon potential. In wells 7128/4,1 and 7128/6,1, the coals have vitrinite reflectance Ro= 0.75,0.85 %. Compared to shale and carbonate source rocks, expulsion from coal in general begins at higher maturities (Ro= 0.8,0.9% and Tmax= 444,453°C). Thus, the coals in the wells are mostly immature with regard to oil expulsion. The oil in well 7128/4,1 most likely originates from a more mature part of the Tettegras Formation in the deeper northern part of the Finnmark Platform. Wide variations in biomarker facies parameters and ,13C isotope values indicate a heterogeneous paralic depositional setting. The preferential retention by coal strata of naphthenes (e.g. terpanes and steranes) and aromatic compounds, compared to n-alkanes and acyclic isoprenoids, results in a terrigenous and waxy oil. This oil however contains marine biomarkers derived from the intercalated shales and siltstones. It is therefore important to consider the entire coal-bearing sequence, including the intercalated shales, in terms of source rock potential. Coals of similar age occur on Svalbard and Bjørnøya. The results of this study therefore suggest that a Lower Carboniferous coaly source rock may extend over large areas of the Norwegian Barents Sea. This source rock is mature in areas where the otherwise prolific Upper Jurassic marine shales are either immature or missing and may constitute a new Palaeozoic coal-sourced petroleum system in the Barents Sea. [source] ORDOVICIAN,PERMIAN PALAEOGEOGRAPHY OF CENTRAL EURASIA: DEVELOPMENT OF PALAEOZOIC PETROLEUM-BEARING BASINSJOURNAL OF PETROLEUM GEOLOGY, Issue 3 2003V. A. Bykadorov In this paper, we discuss three petroleum-bearing basins of Palaeozoic age in Central Eurasia,the Precaspian, Tarim and Chu-Sarysu Basins. We make use of recently-published palaeogeographic maps of the Central Eurasian region, six of which are presented here (Late Ordovician, Early-Middle Devonian, Late Devonian, Early Carboniferous, Early Permian and Late Permian). The maps illustrate the development through the Palaeozoic of the Palaeoasian and Palaeotethys Oceans; of the East European, Siberian and Tarim cratons; and of the Kazakhstan and other microcontinental blocks. The Kazakhstan block formed during the Late Ordovician and is a collage of Precambrian and Early Palaeozoic microcontinents and island arcs. It is surrounded by collisional foldbelts (Ob-Zaisan, Ural-Tianshan and Junggar-Balkhash) which formed in the Late Carboniferous , Permian. We believe that the formation of a stable Kazakhstan block is not consistent with the existence of the previously-identified "Kipchak arc" within the Palaeoasian ocean, or (as has previously been proposed) with activity on this arc up to the end of the Palaeozoic. The oil and gas potential of the Precaspian, Tarim and Chu-Sarysu Basins depends to a large extent on their tectonic stability during the Palaeozoic and subsequent time. The Precaspian Basin has been stable since the Cadomian orogeny (Early Cambrian) and is known to have major hydrocarbon potential. The Tarim Basin (NW China) has somewhat lower potential because the margins of the Tarim continental block have been affected by a series of collisional events; that margin with the Palaeotethys Ocean, for example, was active during the Late Palaeozoic. The Chu-Sarysu Basin on the Kazakhstan block is the least stable of the three and contains only minor gas accumulations. [source] New results concerning the morphology of the most ancient dragonflies (Insecta: Odonatoptera) from the Namurian of Hagen-Vorhalle (Germany)JOURNAL OF ZOOLOGICAL SYSTEMATICS AND EVOLUTIONARY RESEARCH, Issue 4 2001G. Bechly The holotype specimen of the ,protodonate'Erasipteroides valentini (Brauckmann in Brauckmann et al., 1985) and the paratype specimen K-13 of the giant ,protodonate'Namurotypus sippeliBrauckmann and Zessin, 1989 from the Upper Carboniferous (Namurian B) of Hagen-Vorhalle (Germany) are redescribed, and a new specimen of Erasipteroides cf. valentini is described. The new evidence is used to refine the groundplan reconstruction of Odonatoptera and the reconstruction of odonatoid phylogeny. Prothoracic winglets for Erasipteroides and the absence of an archaedictyon are documented. Furthermore, a very long and sclerotized ovipositor with gonangulum is described from the female holotype specimen of Erasipteroides valentini, and it is proposed that it was not used for endophytic but for endosubstratic oviposition. The record of prothoracic winglets in early odonatoids, and their presence in fossil Palaeodictyoptera and ,protorthopteres', indicates that the groundplan of Pterygota indeed included three pairs of wings. A phylogenetic analysis suggests that the Palaeozoic giant Meganisoptera and "higher" odonatoids (incl. crowngroup Odonata) together form a monophyletic group which is here named Euodonatoptera. Erasipteroides and the other ,Erasipteridae' are shown to be more closely related to Euodonatoptera than to Eugeropteridae. The description of the male primary genital structures of Namurotypus sippeli is emended and a new interpretation is proposed, including new hypotheses concerning their function. The males of Namurotypus had a paired penis with a pair of lateral parameres, and a pair of leaf-like, but still segmented, gonopods. Segmented leg-like male gonopods are considered as a groundplan character of insects, while a paired penis is regarded as a putative synapomorphy of the palaeopterous insect orders Palaeodictyopteroida, Ephemeroptera, and Odonatoptera. It is proposed that Namurotypus did not mate by direct copulation but retained the archaic deposition of external spermatophores, just like the primarily wingless insects. The sigmoidal male cerci may have been placed behind the female head and used to drag the female over the spermatophore, which is remotely similar to the mating behaviour of some extant arachnids (e.g. Amblypygi). Three hypothetical scenarios regarding the evolution of secondary copulation in modern Odonata are proposed. Neue Erkenntnisse zur Morphologie der ältesten Libellen (Insecta: Odonatoptera) aus dem Namurium von Hagen-Vorhalle (Deutschland) Das Holotypusexemplar der ,Protodonate'Erasipteroides valentini (Brauckmann in Brauckmann et al., Geol. Paläont. Westfalen 3, 1,131, 1985) und das Paratypusexemplar K-13 der riesenwüchsigen ,Protodonate'Namurotypus sippeliBrauckmann and Zessin, 1989 aus dem Oberkarbon (Namurium B) von Hagen-Vorhalle (Deutschland) werden wiederbeschrieben. Die neuen Erkenntnisse werden zu einer Präzisierung der Grundplanrekonstruktion der Odonatoptera und für die Rekonstruktion der Libellenstammesgeschichte verwendet. Für Erasipteroides werden prothorakale Flügelchen beschrieben und das Fehlen eines Archaedictyons wird belegt. Des weiteren wird ein sehr langer und sklerotisierter Ovipositor mit Gonangulum für das weibliche Holotypusexemplar von Erasipteroides valentini beschrieben, und es wird vorgeschlagen, dass dieser nicht zur endophytischen Eiablage, sondern zur endosubstratischen Eiablage diente. Der Nachweis prothorakaler Flügelchen bei frühen Libellen sowie deren Vorkommen bei fossilen Palaeodictyoptera und ,Protorthopteren', deutet darauf hin, dass zum Grundplan der Pterygota drei Flügelpaare gehörten. Eine phylogenetische Analyse legt nahe, dass die riesenwüchsigen Meganisoptera des Paläozoikums und die ,höheren' Odonaten (inkl. Kronengruppe Odonata) gemeinsam eine monophyletische Gruppe bilden, die hier als Euodonatoptera benannt wird. Es wird gezeigt, dass Erasipteroides und die übrigen ,Erasipteridae' näher mit den Euodonatoptera verwandt sind als die Eugeropteridae. Die Beschreibung der primären männlichen Geschlechtsorgane von Namurotypus sippeli wird ergänzt, und eine neue Interpretation sowie neue Hypothesen zu deren Funktion werden vorgestellt. Die Männchen von Namurotypus besaßen einen paarigen Penis mit einem Paar lateraler Parameren und einem Paar blattartiger, aber noch segmentierter Gonopoden. Segmentierte, beinartige, männliche Gonopoden werden als Grundplanmerkmale der Insekten angesehen, während ein paariger Penis als potentielle Synapomorphie der paläopteren Insektenordnungen Palaeodictyopteroida, Ephemeroptera und Odonatoptera betrachtet wird. Es wird vorgeschlagen, dass die Paarung bei Namurotypus nicht durch eine direkte Kopulation ablief, sondern durch das Absetzen freier Spermatophoren, so wie bei den primär flügellosen Insekten. Die sigmoidalen männlichen Cerci könnten hinter dem weiblichen Kopf platziert worden sein, um das Weibchen über die Spermatophore zu dirigieren, ähnlich dem Paarungsverhalten mancher rezenter Spinnentiere (z.B. Amblypygi). Drei hypothetische Szenarien zur Evolution der sekundären Kopulation bei modernen Libellen werden vorgestellt. [source] Predatory boreholes in Tournaisian (Lower Carboniferous) spiriferid brachiopodsLETHAIA, Issue 3 2009BERNARD MOTTEQUIN A brachiopod fauna from the uppermost part of the Tournaisian Tournai Formation (Belgium) contains an undetermined species of Crurithyris (Spiriferida, Ambocoeliidae), which displays numerous bored shells. About 8% of the 432 specimens with conjoined valves display single, small (, 1 mm) boreholes, which are smooth-sided, cylindrical or weakly conical, circular to slightly elliptical in plan view, perpendicular to the shell surface and generally complete. Of the 35 bored articulated specimens, 27 were drilled on the ventral valve. Most of the boreholes are located in the posterior half of the shell, and no case of edge-drilling has been observed. The boreholes were drilled by a predator, or possibly a parasite, which selected individuals greater than 2.5 mm long. Crurithyris sp. may have represented an attractive (in terms of energy cost) and easy target for a small-sized predator because of its thin shell and ornament of minute spines. [source] Life strategies of solitary undissepimented rugose corals from the upper member of the Picos de Europa Formation (Moscovian, Carboniferous, Cantabrian Mountains, NW Spain)LETHAIA, Issue 3 2001SERGIO RODRÍGUEZ Rugose corals belonging to the orders Metriophyllina, Stereolasmatina and Plerophyllina have been identified in the upper member of the Picos de Europa Formation (Moscovian). Corals occur in crinoidal limestones containing common bryozoans. The coral assemblage shows a high diversity. Mode of preservation and spatial distribution of corals demonstrate close relationships with biogenic components such as crinoids, bryozoans, brachiopods and bivalves. The morphology of corals provides valuable data for identifying their life strategies, four of which have been identified: liberosessile with straight growth, liberosessile with curved growth, fixosessile with straight growth and fixosessile with curved growth. Most corals from the Picos de Europa Formation appear to have been fixosessile with straight growth; they attached themselves to bioclasts and subsequently developed radiciform processes (mainly talons) to remain straight. [source] | |||||||||||||||||||||||||||||||