Sofie Lindström
GEUS Geological Survey of Denmark and Greenland, Stratigraphy, Department Member
Research Interests:
The end-Triassic biotic crisis is generally explained by massive input of CO2 and/or methane to the atmosphere linked to the formation of the Central Atlantic Magmatic Province. Such massive volcanism can be compared to industrial... more
The end-Triassic biotic crisis is generally explained by massive input of CO2 and/or methane to the atmosphere linked to the formation of the Central Atlantic Magmatic Province. Such massive volcanism can be compared to industrial pollution releasing large amounts of the greenhouse gases CO2 and SO2 to the atmosphere. Indeed, the fossil record provides evidence of major perturbations in the �13C-record of both calcareous and organic material. In the marine realm loss of calcifying organisms provides evidence of ocean acidification due to the increased pCO2, while in the terrestrial realm physiological responses in fossil plants indicate intense global warming across the Triassic-Jurassic boundary. Changing climatic conditions is further indicated by charcoal records from Greenland, Denmark, Sweden and Poland showing increased wildfire activity. Increased reworking of palynological material and marked changes in fluvial style in terrestrial successions seem to indicate an increased h...
The East Greenland Ridge (EGR) is a submarine elevation that juts out from the Northeast Greenland shelf, separating the modern Boreas Basin in north from the Greenland Basin in south. The EGR strikes roughly northwest-southeast and lies... more
The East Greenland Ridge (EGR) is a submarine elevation that juts out from the Northeast Greenland shelf, separating the modern Boreas Basin in north from the Greenland Basin in south. The EGR strikes roughly northwest-southeast and lies almost perpendicular to the Mohns Spreading Ridge and sub-parallel to the Knipovich Spreading Ridge. The EGR is about 320 km long and includes several en-echelon elongated crests. The flanks on either side of the EGR are generally high and steep, with escarpments exposing outcropping sub-strata. The EGR has been characterized as a continental sliver. However, this is based on analysis of seismic data only, while no direct evidence has hitherto been published to strengthen this interpretation. In 2012, two up-slope transects on the northeastern lower flank of the EGR were dredged by GEUS and UiT in order to obtain in-situ samples of the outcropping strata. Subsequent work by GEUS on the dredged samples was concentrated on lithological description and...
Research Interests:
Research Interests:
The end-Triassic mass extinction event (201.4 million years ago) caused major faunal and floral turnovers in both the marine and terrestrial realms. The biotic changes have been attributed to extreme greenhouse warming across the... more
The end-Triassic mass extinction event (201.4 million years ago) caused major faunal and floral turnovers in both the marine and terrestrial realms. The biotic changes have been attributed to extreme greenhouse warming across the Triassic–Jurassic (T–J)boundary caused by massive release of carbondioxide and/or methane related to extensive volcanism in the Central Atlantic Magmatic Province(CAMP), resulting in a more humid climate with increased storminess and lightning activity. Lightning strikes are considered the primary source of wildfires, producing charcoal, microscopically recognized as inertinite macerals. The presence of polycyclic aromatic hydrocarbons (PAHs) of pyrolytic origin and allochthonous charcoal in siliciclastic T–J boundary strata has suggested widespread wildfire activity at the time. We have investigated largely autochthonous coal and coaly beds across the T–J boundary in Sweden and Denmark. These beds consist of predominantly organic material from the in situ vegetation in the mires, and as the coaly beds represent a substantial period of time they are excellent environmental archives. We document a remarkable increase in inertinite content in the coal and coaly beds across the T–J boundary. We show estimated burning temperatures derived from inertinite reflectance measurements coupled with palynological data andconclude that pre-boundary late Rhaetian mire wildfires included high-temperature crownfires, whereas latest Rhaetian–Sinemurian mire wildfires were more frequent but dominated by lower temperature surface fires. Our results suggest a major change in the mire ecosystems across the T–J boundary from forested, conifer dominated mires to mires with a predominantly herbaceous and shrubby vegetation. Contrary to the overall regional vegetation for which onset of recovery commenced in the early Hettangian, the sensitive mire ecosystem remained affected during the Hettangian and did not start to recover until around the Hettangian–Sinemurian boundary. Decreasing inertinite content through the Lower Jurassic suggests that fire activity gradually resumed to considerable lower levels.
Research Interests:
The evolution of complex life over the past 600 million years was disrupted by at least five mass extinctions, one of which occurred at the close of the Triassic period. The end-Triassic extinction corresponds to a period of high... more
The evolution of complex life over the past 600 million years was disrupted by at least five mass extinctions, one of which occurred at the close of the Triassic period. The end-Triassic extinction corresponds to a period of high atmospheric-CO2 concentrations caused by massive volcanism and biomass burning; most extinction scenarios invoke the resulting environmental perturbations in accounting for the loss of marine and terrestrial biodiversity. Here we reconstruct changes in Tethyan shallow marine ecosystems and ocean redox chemistry from earliest Jurassic (Hettangian)-aged black shales from Germany and Luxemburg. The shales contain increased concentrations of the biomarker isorenieratane, a fossilized pigment from green sulphur bacteria. The abundance of green sulphur bacteria suggests that the photic zone underwent prolonged periods of high concentrations of hydrogen sulphide. This interval is also marked by the proliferation of green algae, an indicator of anoxia. We conclude that the redox changes in the entire water column reflect sluggish circulation in marginal regions of the Tethys Ocean. We suggest that the resultant repeated poisoning of shallow epicontinental seas—hotspots of Mesozoic biodiversity—with hydrogen sulphide may have slowed the recovery of marine ecosystems during the Early Jurassic.
Research Interests:
The probable zygnematacean zygospore Tetranguladinium is for the first time recorded in Mesozoic strata from southern Scandinavia. Tetranguladinium, which exhibits morphological similarities to the extant filamentous green alga Mougeotia,... more
The probable zygnematacean zygospore Tetranguladinium is for the first time recorded in Mesozoic strata from southern Scandinavia. Tetranguladinium, which exhibits morphological similarities to the extant filamentous green alga Mougeotia, occurs in Jurassic-Cretaceous (J/K) boundary (latest Tithonian-early Berriasian) assemblages from the Vomb Trough, southern Sweden, and on the Danish island of Bornholm. The J/K boundary strata of southern Scandinavia were deposited in marginal marine settings, varying from freshwater marshes, lakes and floodplains, to lagoons, shore-face, and shallow marine to fully marine environments. The assemblages containing Tetranguladinium are diverse, consisting of spores and pollen, the colonial green alga Botryococcus, various other zygnematacean zygospores e.g. Ovoidites, Schizosporis and Tetraporina, and rare marine dinoflagellate cysts.
A review of published fossil occurrences of Tetranguladinium reveals that its stratigraphic range extends at least from the late Guadalupian (Middle Permian) to the Holocene. It has been recorded from Africa (Tanzania), Asia (China, Korea), Australia, NW Europe (Denmark, Great Britain, Sweden), North America (Canada, USA), and South America (Argentina). Depositional and palaeoclimatological data for the known localities of Tetranguladinium confirm a preference for freshwater settings in a humid warm temperate to subtropical-tropical climate often with a pronounced dry season. The palaeogeographical positions of all the known Tetranguladinium localities indicate that it is has stayed restricted within narrow belts between 30-40º south and 30-60° north of the palaeoequator since the Late Jurassic.
A review of published fossil occurrences of Tetranguladinium reveals that its stratigraphic range extends at least from the late Guadalupian (Middle Permian) to the Holocene. It has been recorded from Africa (Tanzania), Asia (China, Korea), Australia, NW Europe (Denmark, Great Britain, Sweden), North America (Canada, USA), and South America (Argentina). Depositional and palaeoclimatological data for the known localities of Tetranguladinium confirm a preference for freshwater settings in a humid warm temperate to subtropical-tropical climate often with a pronounced dry season. The palaeogeographical positions of all the known Tetranguladinium localities indicate that it is has stayed restricted within narrow belts between 30-40º south and 30-60° north of the palaeoequator since the Late Jurassic.
Research Interests:
Profound changes in both marine and terrestrial biota during the end-Triassic mass extinction event and associated successive carbon cycle perturbations across the Triassic-Jurassic boundary (T-J, 201.3 Ma) have primarily been attributed... more
Profound changes in both marine and terrestrial biota during the end-Triassic mass extinction event and associated successive carbon cycle perturbations across the Triassic-Jurassic boundary (T-J, 201.3 Ma) have primarily been attributed to volcanic emissions from the Central Atlantic Magmatic Province and/or injection of methane. Here we present a new extended organic carbon isotope record from a cored T-J boundary succession in the Danish Basin, dated by high-resolution palynostratigraphy and supplemented by a marine faunal record. Correlated with reference C-isotope and biotic records from the UK, it provides new evidence that the major biotic changes, both on land and in the oceans, commenced prior to the most prominent negative C-isotope excursion. If massive methane release was involved, it did not trigger the end-Triassic mass extinction. Instead, this negative C-isotope excursion is contemporaneous with the onset of floral recovery on land, whereas marine ecosystems remained perturbed. The decoupling between ecosystem recovery on land and in the sea is more likely explained by long-term flood basalt volcanism releasing both SO2 and CO2 with short- and long-term effects, respectively.
Research Interests:
Research Interests:
The end-Triassic mass extinction event is estimated to have caused the disappearance of several marine families (23%) and genera (50%) on a global scale (Hallam and Wignall, 1999; van de Schootbrugge et al. 2007). In the terrestrial realm... more
The end-Triassic mass extinction event is estimated to have caused the disappearance of several marine families (23%) and genera (50%) on a global scale (Hallam and Wignall, 1999; van de Schootbrugge et al. 2007). In the terrestrial realm regional to supraregional losses of vertebrate families (up to 42%) and plant species (up to 95%) have been recorded (McElwain et al, 1999, 2007; Olsen et al., 2002; Whiteside et al., 2007). The event is temporally linked to the flood basalt volcanism of the Central Atlantic Magmatic Province (CAMP)(Schoene et al. 2010) and major perturbations in the carbon cycle recorded in stable carbon isotope records globally are generally attributed to the effects of outgassing of 12C-enriched CO2 from this large igneous province (Hesselbo et al., 2002). However, recently injection of methane was put forward as a more likely cause for the most prominent C-isotope excursion, and thus also as a trigger of the end-Triassic mass extinction (Ruhl and Kürschner, 2011; Ruhl et al, 2011).
High resolution palynological and bulk organic C-isotope data from Triassic–Jurassic (T/J) successions in Denmark and Sweden provide evidence of major and partly coeval shifts in the marine and terrestrial palynofloras. The demise of typical Rhaetian dinoflagellate cysts and the temporary disappearance of these phytoplankton appear to coincide with an interval indicating terrestrial deforestation marked by a major decline in pollen from conifers, cycads and ginkgos. Instead high abundances of fern spores, the enigmatic pollen Ricciisporites tuberculatus and sphaeromorphs totally dominate the assemblages. Additional significant features of this interval within the basin, include increased erosion and reworking, changes in fluvial style and temporary loss of peat-forming vegetation.
Correlation between the organic C-isotope record and the terrestrial and marine biotic changes in the Danish Basin show that the major environmental perturbations took place prior to the most prominent negative C-isotope excursion. The subsequent reorganisation and recovery of the terrestrial ecosystem already commenced during this peak, hence negating injection of methane as a major cause of the end-Triassic mass extinction event. Instead we favour a scenario in which repeated episodic CO2 and SO2 release from the CAMP played a prominent role (van de Schootbrugge et al., 2009). Many of the changes recorded in the T/J-boundary succession of the Danish Basin can be attributed to outgassing of SO2 from the CAMP, and subsequent acid rain and acid deposition, and subsequent feedback effects.
References
Hallam, A. and Wignall, P.B. (1999). Mass extinctions and sea-level changes. Earth Sci. Rev., 48, 217-250.
Hesselbo, S.P., Robinson, S.A., Surlyk, F. and Piasecki, S. (2002). Terrestrial and marine extinction at the Triassic-Jurassic boundary synchronized with major carbon-cycle perturbations: A link to initiation of massive volcanism? Geology 30, 251-254.
McElwain, J.C., Beerling, D.J. and Woodward, F.I. (1999). Fossil plants and global warming at the Triassic-Jurassic boundary. Science 285, 1386-1390.
McElwain, J.C., Popa, M.E., Hesselbo, S.P., Haworth, M. and Surlyk, F. (2007). Macroecological responses of terrestrial vegetation to climate and atmospheric change across the Triassic/Jurassic boundary in East Greenland. Paleobiology 33, 547-573.
Olsen, P.E., Kent, D.V., Sues, H.D., Koeberl, C., Huberm H., Montanari, A., Rainforth, E.C., Fowell, S.J., Szajna, M.J. and Hartline, B.W. (2002). Ascent of dinosaurs linked to Ir anomaly at Triassic–Jurassic boundary. Science 296, 1305-1307.
Ruhl, M. and Kürschner, W.M., 2011, Multiple phases of carbon cycle disturbance from large igneous province formation at the Triassic-Jurassic transition: Geology, 39, p. 431-434.
Ruhl, M., Bonis, N.R., Reichart, G.-J., Sinninghe Damsté, J.S., and Kürschner, W.M., 2011, Atmospheric carbon injection linked to end-Triassic mass extinction: Science, v. 333, p. 430-434.
Schoene, B., Guex, J., Bartolini, A., Schaltegger, U. and Blackburn, T.J. (2010). Correlating the end-Triassic mass extinction and flood basalt volcanism at the 100 ka level. Geology 38, 387-390.
van de Schootbrugge, B., Tremolada, F., Bailey, T.R., Rosenthal, Y., Feist-Burkhardt, S., Brinkhuis, H., Pross, J., Kent, D.V. and Falkowski, P.G. (2007). End-Triassic calcification crisis and blooms of organic-walled disaster species. Palaeogeogr. Palaeoclimatol. Palaeoecol. 244, 126-141.
van de Schootbrugge, B., Quan, T.M., Lindström, S., Püttmann, W., Heunisch, C., Pross, J., Fiebig, J., Petschik, R., Röhling, H.-G., Richoz, S., Rosenthal, Y. and Falkowski, P.G. (2009). Floral changes across the Triassic/Jurassic boundary linked to flood basalt volcanism. Nature Geoscience 2, 589-594.
Whiteside, J.H., Olsen, P.E., Kent, D.V., Fowell, S.J. and Et-Touhami, M. (2007). Synchrony between the Central Atlantic magmatic province and the Triassic–Jurassic mass-extinction event? Palaeogeogr. Palaeoclimatol. Palaeoecol., 244, 345-367.
High resolution palynological and bulk organic C-isotope data from Triassic–Jurassic (T/J) successions in Denmark and Sweden provide evidence of major and partly coeval shifts in the marine and terrestrial palynofloras. The demise of typical Rhaetian dinoflagellate cysts and the temporary disappearance of these phytoplankton appear to coincide with an interval indicating terrestrial deforestation marked by a major decline in pollen from conifers, cycads and ginkgos. Instead high abundances of fern spores, the enigmatic pollen Ricciisporites tuberculatus and sphaeromorphs totally dominate the assemblages. Additional significant features of this interval within the basin, include increased erosion and reworking, changes in fluvial style and temporary loss of peat-forming vegetation.
Correlation between the organic C-isotope record and the terrestrial and marine biotic changes in the Danish Basin show that the major environmental perturbations took place prior to the most prominent negative C-isotope excursion. The subsequent reorganisation and recovery of the terrestrial ecosystem already commenced during this peak, hence negating injection of methane as a major cause of the end-Triassic mass extinction event. Instead we favour a scenario in which repeated episodic CO2 and SO2 release from the CAMP played a prominent role (van de Schootbrugge et al., 2009). Many of the changes recorded in the T/J-boundary succession of the Danish Basin can be attributed to outgassing of SO2 from the CAMP, and subsequent acid rain and acid deposition, and subsequent feedback effects.
References
Hallam, A. and Wignall, P.B. (1999). Mass extinctions and sea-level changes. Earth Sci. Rev., 48, 217-250.
Hesselbo, S.P., Robinson, S.A., Surlyk, F. and Piasecki, S. (2002). Terrestrial and marine extinction at the Triassic-Jurassic boundary synchronized with major carbon-cycle perturbations: A link to initiation of massive volcanism? Geology 30, 251-254.
McElwain, J.C., Beerling, D.J. and Woodward, F.I. (1999). Fossil plants and global warming at the Triassic-Jurassic boundary. Science 285, 1386-1390.
McElwain, J.C., Popa, M.E., Hesselbo, S.P., Haworth, M. and Surlyk, F. (2007). Macroecological responses of terrestrial vegetation to climate and atmospheric change across the Triassic/Jurassic boundary in East Greenland. Paleobiology 33, 547-573.
Olsen, P.E., Kent, D.V., Sues, H.D., Koeberl, C., Huberm H., Montanari, A., Rainforth, E.C., Fowell, S.J., Szajna, M.J. and Hartline, B.W. (2002). Ascent of dinosaurs linked to Ir anomaly at Triassic–Jurassic boundary. Science 296, 1305-1307.
Ruhl, M. and Kürschner, W.M., 2011, Multiple phases of carbon cycle disturbance from large igneous province formation at the Triassic-Jurassic transition: Geology, 39, p. 431-434.
Ruhl, M., Bonis, N.R., Reichart, G.-J., Sinninghe Damsté, J.S., and Kürschner, W.M., 2011, Atmospheric carbon injection linked to end-Triassic mass extinction: Science, v. 333, p. 430-434.
Schoene, B., Guex, J., Bartolini, A., Schaltegger, U. and Blackburn, T.J. (2010). Correlating the end-Triassic mass extinction and flood basalt volcanism at the 100 ka level. Geology 38, 387-390.
van de Schootbrugge, B., Tremolada, F., Bailey, T.R., Rosenthal, Y., Feist-Burkhardt, S., Brinkhuis, H., Pross, J., Kent, D.V. and Falkowski, P.G. (2007). End-Triassic calcification crisis and blooms of organic-walled disaster species. Palaeogeogr. Palaeoclimatol. Palaeoecol. 244, 126-141.
van de Schootbrugge, B., Quan, T.M., Lindström, S., Püttmann, W., Heunisch, C., Pross, J., Fiebig, J., Petschik, R., Röhling, H.-G., Richoz, S., Rosenthal, Y. and Falkowski, P.G. (2009). Floral changes across the Triassic/Jurassic boundary linked to flood basalt volcanism. Nature Geoscience 2, 589-594.
Whiteside, J.H., Olsen, P.E., Kent, D.V., Fowell, S.J. and Et-Touhami, M. (2007). Synchrony between the Central Atlantic magmatic province and the Triassic–Jurassic mass-extinction event? Palaeogeogr. Palaeoclimatol. Palaeoecol., 244, 345-367.
Research Interests:
The 116 m deep Fårarp-1 core drilled in the Vomb Trough in southernmost Sweden is dated by integrated terrestrial and marine palynostratigraphy. The lower part of the succession (ca 84 m) encompasses uppermost Jurassic to lowermost... more
The 116 m deep Fårarp-1 core drilled in the Vomb Trough in southernmost Sweden is dated by integrated terrestrial and marine palynostratigraphy. The lower part of the succession (ca 84 m) encompasses uppermost Jurassic to lowermost Cretaceous (uppermost Tithonian to Valanginian) strata. An unconformity separates the Valanginian strata from an overlying ca 1 m thick interval of upper Albian to Cenomanian Arnager Greensand Formation. The uppermost part of the core is a repetitive succession of lowermost Cretaceous sediments.
During the Jurassic–Cretaceous (J/K) transition NW Europe was located in mid latitudes, and comprised an archipelago of large and small islands separated by deeper grabens and epicontinental seaways that connected the Boreal Sea to the north with the warmer Tethys Ocean to the south. Boundary strata in England, France, the Netherlands and Germany are characterised by relatively prominent climatic change from arid/semi arid to subhumid/humid conditions. Southernmost Sweden was located on the margin of a large landmass comprising most of the Fennoscandian Shield bordering a large epicontinental sea to the west. By combining sedimentology, clay mineralogy and palynofacies the Tithonian to Valanginian cored succession of the Fårarp-1 core provides complementary information on how marginal deposits from the eastern part of the epicontinental sea reflect the climatological and environmental changes observed in other parts of NW Europe.
The Fårarp-1 core shows that during the Tithonian to earliest Berriasian deposition took place in a terrestrial but near-marine depositional setting, in coastal lakes or lagoons with little marine influence. A dry climatic regime favoured stagnant water conditions with common algal blooms of primarily Botryococcus and zygnemataceae. Palynofacies and sedimentology indicate limited transport of freshwater and material to the basin. The stagnant depositional environment was terminated by a marine flooding in the early Berriasian. During the remaining Berriasian and the early Valanginian conditions shifted between near marine and marine settings in a dynamic coastal environment, similar to contemporaneous assemblages reported from the Danish Island of Bornholm.
A shift in clay mineralogy, from a dominance of 10 Å minerals to increasing amounts of mixed layer and kaolinite indicates a change to more humid conditions in the latest Tithonian. Cheirolepidacean pollen (Classopollis) are present but never common in the cored succession, and a similar conspicuous decrease of these pollen, as previously reported from England, Germany and France, is not evident in the Fårarp-1 core. Instead a subsequent shift in both palynofacies and palynoflora, marked by an increase in abundance of heavy terrigenous material, i.e. wood and coal particles, upland pollen grains and reworked palynomorphs is also observed in the uppermost Tithonian–lowermost Berriasian interval. At the same level spores and pollen classified as warmer/drier elements decrease in abundance. This is interpreted as representing a shift to more humid climatic conditions with increased runoff from the hinterland. Thus, the combined sedimentological and palynological data from the Fårarp-1 core suggest that climatic conditions in the area changed from more seasonally dry (semi-arid) to more humid (semi-humid) across the J/K boundary (latest Tithonian to earliest Berriasian) and hence earlier than the mid-Berriasian climatic shift recorded from e.g. England and the Netherlands.
During the Jurassic–Cretaceous (J/K) transition NW Europe was located in mid latitudes, and comprised an archipelago of large and small islands separated by deeper grabens and epicontinental seaways that connected the Boreal Sea to the north with the warmer Tethys Ocean to the south. Boundary strata in England, France, the Netherlands and Germany are characterised by relatively prominent climatic change from arid/semi arid to subhumid/humid conditions. Southernmost Sweden was located on the margin of a large landmass comprising most of the Fennoscandian Shield bordering a large epicontinental sea to the west. By combining sedimentology, clay mineralogy and palynofacies the Tithonian to Valanginian cored succession of the Fårarp-1 core provides complementary information on how marginal deposits from the eastern part of the epicontinental sea reflect the climatological and environmental changes observed in other parts of NW Europe.
The Fårarp-1 core shows that during the Tithonian to earliest Berriasian deposition took place in a terrestrial but near-marine depositional setting, in coastal lakes or lagoons with little marine influence. A dry climatic regime favoured stagnant water conditions with common algal blooms of primarily Botryococcus and zygnemataceae. Palynofacies and sedimentology indicate limited transport of freshwater and material to the basin. The stagnant depositional environment was terminated by a marine flooding in the early Berriasian. During the remaining Berriasian and the early Valanginian conditions shifted between near marine and marine settings in a dynamic coastal environment, similar to contemporaneous assemblages reported from the Danish Island of Bornholm.
A shift in clay mineralogy, from a dominance of 10 Å minerals to increasing amounts of mixed layer and kaolinite indicates a change to more humid conditions in the latest Tithonian. Cheirolepidacean pollen (Classopollis) are present but never common in the cored succession, and a similar conspicuous decrease of these pollen, as previously reported from England, Germany and France, is not evident in the Fårarp-1 core. Instead a subsequent shift in both palynofacies and palynoflora, marked by an increase in abundance of heavy terrigenous material, i.e. wood and coal particles, upland pollen grains and reworked palynomorphs is also observed in the uppermost Tithonian–lowermost Berriasian interval. At the same level spores and pollen classified as warmer/drier elements decrease in abundance. This is interpreted as representing a shift to more humid climatic conditions with increased runoff from the hinterland. Thus, the combined sedimentological and palynological data from the Fårarp-1 core suggest that climatic conditions in the area changed from more seasonally dry (semi-arid) to more humid (semi-humid) across the J/K boundary (latest Tithonian to earliest Berriasian) and hence earlier than the mid-Berriasian climatic shift recorded from e.g. England and the Netherlands.
Research Interests:
The end-Triassic mass extinction event is estimated to have caused the disappearance of several marine families (23%) and genera (50%) on a global scale (Hallam and Wignall, 1999; van de Schootbrugge et al. 2007). In the terrestrial realm... more
The end-Triassic mass extinction event is estimated to have caused the disappearance of several marine families (23%) and genera (50%) on a global scale (Hallam and Wignall, 1999; van de Schootbrugge et al. 2007). In the terrestrial realm regional to supraregional losses of vertebrate families (up to 42%) and plant species (up to 95%) have been recorded (McElwain et al, 1999, 2007; Olsen et al., 2002; Whiteside et al., 2007). The event is temporally linked to the flood basalt volcanism of the Central Atlantic Magmatic Province (CAMP)(Schoene et al. 2010) and major perturbations in the carbon cycle recorded in stable carbon isotope records globally are generally attributed to the effects of outgassing of 12C-enriched CO2 from this large igneous province (Hesselbo et al., 2002).
High resolution palynological and bulk organic C-isotope data from Triassic–Jurassic (T/J) successions in Denmark and Sweden provide evidence of major and partly coeval shifts in the marine and terrestrial palynofloras. The demise of typical Rhaetian dinoflagellate cysts and the temporary disappearance of these phytoplankton appear to coincide with an interval indicating terrestrial deforestation marked by a major decline in pollen from conifers, cycads and ginkgos. Instead high abundances of fern spores, the enigmatic pollen Ricciisporites tuberculatus and sphaeromorphs totally dominate the assemblages. Additional significant features of this interval within the basin, include increased erosion and reworking, changes in fluvial style and temporary loss of peat-forming vegetation.
Many of the changes recorded in the T/J-boundary succession of the Danish Basin can be attributed to outgassing of SO2 from the CAMP, and subsequent acid rain and acid deposition (van de Schootbrugge et al. 2009). However, the high abundance of sphaeromorphs within the end-Triassic event interval of the Danish Basin remains enigmatic. There are two working hypotheses for the mass occurrence of these sphaeromorphs: 1) They are in situ and represent a prasinophycean algal bloom. 2) They are reworked and represent a phase of increased weathering and erosion. The possible causes, consequences, as well as palaeoecological significance of these two hypotheses on the interpretation of the end-Triassic event will be discussed.
References
Hallam, A. and Wignall, P.B. (1999). Mass extinctions and sea-level changes. Earth Sci. Rev., 48, 217-250.
Hesselbo, S.P., Robinson, S.A., Surlyk, F. and Piasecki, S. (2002). Terrestrial and marine extinction at the Triassic-Jurassic boundary synchronized with major carbon-cycle perturbations: A link to initiation of massive volcanism? Geology 30, 251-254.
McElwain, J.C., Beerling, D.J. and Woodward, F.I. (1999). Fossil plants and global warming at the Triassic-Jurassic boundary. Science 285, 1386-1390.
McElwain, J.C., Popa, M.E., Hesselbo, S.P., Haworth, M. and Surlyk, F. (2007). Macroecological responses of terrestrial vegetation to climate and atmospheric change across the Triassic/Jurassic boundary in East Greenland. Paleobiology 33, 547-573.
Olsen, P.E., Kent, D.V., Sues, H.D., Koeberl, C., Huberm H., Montanari, A., Rainforth, E.C., Fowell, S.J., Szajna, M.J. and Hartline, B.W. (2002). Ascent of dinosaurs linked to Ir anomaly at Triassic–Jurassic boundary. Science 296, 1305-1307.
Schoene, B., Guex, J., Bartolini, A., Schaltegger, U. and Blackburn, T.J. (2010). Correlating the end-Triassic mass extinction and flood basalt volcanism at the 100 ka level. Geology 38, 387-390.
van de Schootbrugge, B., Tremolada, F., Bailey, T.R., Rosenthal, Y., Feist-Burkhardt, S., Brinkhuis, H., Pross, J., Kent, D.V. and Falkowski, P.G. (2007). End-Triassic calcification crisis and blooms of organic-walled disaster species. Palaeogeogr. Palaeoclimatol. Palaeoecol. 244, 126-141.
van de Schootbrugge, B., Quan, T.M., Lindström, S., Püttmann, W., Heunisch, C., Pross, J., Fiebig, J., Petschik, R., Röhling, H.-G., Richoz, S., Rosenthal, Y. and Falkowski, P.G. (2009). Floral changes across the Triassic/Jurassic boundary linked to flood basalt volcanism. Nature Geoscience 2, 589-594.
Whiteside, J.H., Olsen, P.E., Kent, D.V., Fowell, S.J. and Et-Touhami, M. (2007). Synchrony between the Central Atlantic magmatic province and the Triassic–Jurassic mass-extinction event? Palaeogeogr. Palaeoclimatol. Palaeoecol., 244, 345-367.
High resolution palynological and bulk organic C-isotope data from Triassic–Jurassic (T/J) successions in Denmark and Sweden provide evidence of major and partly coeval shifts in the marine and terrestrial palynofloras. The demise of typical Rhaetian dinoflagellate cysts and the temporary disappearance of these phytoplankton appear to coincide with an interval indicating terrestrial deforestation marked by a major decline in pollen from conifers, cycads and ginkgos. Instead high abundances of fern spores, the enigmatic pollen Ricciisporites tuberculatus and sphaeromorphs totally dominate the assemblages. Additional significant features of this interval within the basin, include increased erosion and reworking, changes in fluvial style and temporary loss of peat-forming vegetation.
Many of the changes recorded in the T/J-boundary succession of the Danish Basin can be attributed to outgassing of SO2 from the CAMP, and subsequent acid rain and acid deposition (van de Schootbrugge et al. 2009). However, the high abundance of sphaeromorphs within the end-Triassic event interval of the Danish Basin remains enigmatic. There are two working hypotheses for the mass occurrence of these sphaeromorphs: 1) They are in situ and represent a prasinophycean algal bloom. 2) They are reworked and represent a phase of increased weathering and erosion. The possible causes, consequences, as well as palaeoecological significance of these two hypotheses on the interpretation of the end-Triassic event will be discussed.
References
Hallam, A. and Wignall, P.B. (1999). Mass extinctions and sea-level changes. Earth Sci. Rev., 48, 217-250.
Hesselbo, S.P., Robinson, S.A., Surlyk, F. and Piasecki, S. (2002). Terrestrial and marine extinction at the Triassic-Jurassic boundary synchronized with major carbon-cycle perturbations: A link to initiation of massive volcanism? Geology 30, 251-254.
McElwain, J.C., Beerling, D.J. and Woodward, F.I. (1999). Fossil plants and global warming at the Triassic-Jurassic boundary. Science 285, 1386-1390.
McElwain, J.C., Popa, M.E., Hesselbo, S.P., Haworth, M. and Surlyk, F. (2007). Macroecological responses of terrestrial vegetation to climate and atmospheric change across the Triassic/Jurassic boundary in East Greenland. Paleobiology 33, 547-573.
Olsen, P.E., Kent, D.V., Sues, H.D., Koeberl, C., Huberm H., Montanari, A., Rainforth, E.C., Fowell, S.J., Szajna, M.J. and Hartline, B.W. (2002). Ascent of dinosaurs linked to Ir anomaly at Triassic–Jurassic boundary. Science 296, 1305-1307.
Schoene, B., Guex, J., Bartolini, A., Schaltegger, U. and Blackburn, T.J. (2010). Correlating the end-Triassic mass extinction and flood basalt volcanism at the 100 ka level. Geology 38, 387-390.
van de Schootbrugge, B., Tremolada, F., Bailey, T.R., Rosenthal, Y., Feist-Burkhardt, S., Brinkhuis, H., Pross, J., Kent, D.V. and Falkowski, P.G. (2007). End-Triassic calcification crisis and blooms of organic-walled disaster species. Palaeogeogr. Palaeoclimatol. Palaeoecol. 244, 126-141.
van de Schootbrugge, B., Quan, T.M., Lindström, S., Püttmann, W., Heunisch, C., Pross, J., Fiebig, J., Petschik, R., Röhling, H.-G., Richoz, S., Rosenthal, Y. and Falkowski, P.G. (2009). Floral changes across the Triassic/Jurassic boundary linked to flood basalt volcanism. Nature Geoscience 2, 589-594.
Whiteside, J.H., Olsen, P.E., Kent, D.V., Fowell, S.J. and Et-Touhami, M. (2007). Synchrony between the Central Atlantic magmatic province and the Triassic–Jurassic mass-extinction event? Palaeogeogr. Palaeoclimatol. Palaeoecol., 244, 345-367.
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One of the five largest mass extinctions of the past 600 million years occurred at the boundary of the Triassic and Jurassic periods, 201.6 million years ago. The loss of marine biodiversity at the time has been linked to extreme... more
One of the five largest mass extinctions of the past 600 million years occurred at the boundary of the Triassic and Jurassic periods, 201.6 million years ago. The loss of marine biodiversity at the time has been linked to extreme greenhouse warming, triggered by the release of carbon dioxide from flood basalt volcanism in the central Atlantic Ocean. In contrast, the biotic turnover in terrestrial ecosystems is not well understood, and cannot be readily reconciled with the effects of massive volcanism. Here we present pollen, spore and geochemical analyses across the Triassic/Jurassic boundary from three drill cores from Germany and Sweden. We show that gymnosperm forests in northwest Europe were transiently replaced by fern and fern-associated vegetation, a pioneer assemblage commonly found in disturbed ecosystems. The Triassic/Jurassic
boundary is also marked by an enrichment of polycyclic aromatic hydrocarbons, which, in the absence of charcoal peaks, we interpret as an indication of incomplete combustion of organic matter by ascending flood basalt lava. We conclude that the terrestrial vegetation shift is so severe and wide ranging that it is unlikely to have been triggered by greenhouse warming
alone. Instead, we suggest that the release of pollutants such as sulphur dioxide and toxic compounds such as the polycyclic
aromatic hydrocarbons may have contributed to the extinction.
boundary is also marked by an enrichment of polycyclic aromatic hydrocarbons, which, in the absence of charcoal peaks, we interpret as an indication of incomplete combustion of organic matter by ascending flood basalt lava. We conclude that the terrestrial vegetation shift is so severe and wide ranging that it is unlikely to have been triggered by greenhouse warming
alone. Instead, we suggest that the release of pollutants such as sulphur dioxide and toxic compounds such as the polycyclic
aromatic hydrocarbons may have contributed to the extinction.
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Coals with similar thermal maturity and from the same deposit normally show a considerable range in petroleum generation potential as measured by the Hydrogen Index (HI). This variation may partly be related to variations in plant input... more
Coals with similar thermal maturity and from the same deposit normally show a considerable range in petroleum generation potential as measured by the Hydrogen Index (HI). This variation may partly be related to variations in plant input to the precursor mires and organic matter preservation. It is widely accepted that some Cenozoic coals and coaly sediments have the potential to generate oil, which is related to the coal's paraffinicity. Coal paraffinicity is not readily reflected in the bulk HI. In this paper, the relationships between measured HI and coal composition, coal kerogen paraffinicity and floral input have been investigated in detail for three sets of coals from Colombia/Venezuela, Indonesia, and Vietnam. The samples in each coal set are largely of iso-rank. The petroleum generation potential was determined by Rock–Eval pyrolysis. Reflected light microscopy was used to analyse the organic matter (maceral) composition and the thermal maturity was determined by vitrinite reflectance (VR) measurements. The botanical affinity of pollen and spores was analysed by palynology. Coal kerogen paraffinicity was determined by ruthenium tetroxide-catalysed oxidation (RTCO) followed by chain length analysis and quantification (mg/g TOC) of the liberated aliphatic chains. The coals are dominated by huminite, in particular detrohuminite. Only the Vietnamese coals are rich in microscopically visible liptinite. The pollen and spores suggest that the coals were derived principally from complex angiosperm mire vegetations, with subordinate proportions of ferns that generally grew in a subtropical to tropical climate. Measured HI values vary considerably, but for the majority of the coals the values lie between approximately 200 mg HC/g TOC and 300 mg HC/g TOC. Aliphatics yielding monocarboxylic acids dominate in the coal kerogen, whereas aliphatics yielding dicarboxylic acids are secondary. However, the dicarboxylic acids show that cross-linking long-chain aliphatics are present in the kerogen structure. All studied coals are paraffinic with C19–35 aliphatic chains in the kerogen, and the aliphatics in the range C25–35 show that the coals may have the potential to generate waxy crude oil. The Indonesian coals are richest in long-chain aliphatics and are thus potentially most oil-prone. Multivariate statistical analysis shows that for the present three sample sets variations in HI are positively correlated to different combinations of the C10+ aliphatic chains in the kerogen and the amount of detrohuminite + liptodetrinite and liptinite. Furthermore, part of the HI can be attributed to hydrogen in compounds with less than 10 carbon atoms, which is the lowest alkyl detected by RTCO analysis, thus representing a potential for generation of gas and light liquid hydrocarbons. The measured HI is therefore not always a good indicator for humic coal's potential to source waxy oil. Vegetational influence (palynology) on the variation of HI cannot be shown within the investigated span of variance and for the present coals. However, it is likely that some of the range in measured HI values is caused by floral vairiations not revealed by the palynological analysis and to variations in the preservation of the organic matter.
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The small Neogene Krong Pa graben is situated within the continental Song Ba Rift, which is bounded by strike-slip faults that were reactivated as extensional faults in Middle Miocene time. The 500 m thick graben-fill shows an overall... more
The small Neogene Krong Pa graben is situated within the continental Song Ba Rift, which is bounded by strike-slip faults that were reactivated as extensional faults in Middle Miocene time. The 500 m thick graben-fill shows an overall depositional development reflecting the structural evolution, which is very similar to much larger and longer-lived graben. The basal graben-fill consists of thin fluvial sandstones interbedded with well-oxygenated lacustrine siltstones in the basin centre, while very coarse-grained fluvial sandstones and conglomerates dominate at the basin margins. With increased subsidence rate and possibly a higher influx of water from the axial river systems the general water level in the graben rose and deep lakes formed. High organic preservation in the lakes prompted the formation of two excellent oil-prone lacustrine source-rock units. In the late phase of the graben development sedimentation rate outpaced the formation of accommodation space and fluvial activity increased again. During periods when the general sedimentation rate was in balance with the creation of accommodation space the environment changed frequently between lake deposition and intermittent vigorous fluvial activity. It is likely that the resulting interbedding of fluvial sandstones and lacustrine sediments reflects variations in precipitation. In periods of little precipitation the lakes diminished and lake bottoms became exposed. After heavy precipitation, transverse river systems transported sands from the rift shoulders across the exposed lake bottom and fluvial sands were deposited on lake bottom sediments. Subsequently, lake level rose due to increased water supply from the axial river and the sands were drowned and topped by transgressive lacustrine mudstones. These sandstones may function as carrier beds, whereas the braided fluvial sandstones and conglomerates along the graben margins may form reservoirs. The Krong Pa graben thus contains oil-prone lacustrine source rocks, effective conduits for generated hydrocarbons and reservoir sandstones side-sealed by the graben faults toward the footwall granites. In addition to the structural and climatic signals recorded by the graben-fill, sediment partitioning among the partly isolated basins along the rift axis seems to have been important.
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... S. Lindström (1), B. van de Schootbrugge (2), K. Dybkjær (1), S. Richoz (3), C. Heunisch (4), LH Nielsen (1), and M. Erlström (5) (1) Geocenter Denmark, Geological Survey of Denmark and Greenland, Copenhagen, Denmark (sli@geus.dk,... more
... S. Lindström (1), B. van de Schootbrugge (2), K. Dybkjær (1), S. Richoz (3), C. Heunisch (4), LH Nielsen (1), and M. Erlström (5) (1) Geocenter Denmark, Geological Survey of Denmark and Greenland, Copenhagen, Denmark (sli@geus.dk, sofie.lindstrom@geol.lu.se), (2 ...
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(1) Geological Survey of Denmark and Greenland, Copenhagen, Denmark (sli@ geus. dk, sofie. lindstrom@ geol. lu. se, kd@ geus. dk, lhn@ geus. dk),(2) Institute for Geosciences, Frankfurt University, Paleoceanography and Micropaleontology,... more
(1) Geological Survey of Denmark and Greenland, Copenhagen, Denmark (sli@ geus. dk, sofie. lindstrom@ geol. lu. se, kd@ geus. dk, lhn@ geus. dk),(2) Institute for Geosciences, Frankfurt University, Paleoceanography and Micropaleontology, Frankfurt am Main, ...
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In the Prince Charles Mountains (PCMs) the conformable Permian–Triassic (P–T) succession is characterised by an abrupt transition from coal-bearing to coal-lacking strata, which coincides with the demise of the Permian... more
In the Prince Charles Mountains (PCMs) the conformable Permian–Triassic (P–T) succession is characterised by an abrupt transition from coal-bearing to coal-lacking strata, which coincides with the demise of the Permian Glossopteris-dominated flora. About 32% of the typical Permian spores and pollen are registered for the last time in the uppermost coal. Throughout the earliest Triassic an additional 34% of the lingering Permian taxa disappear, while pioneering typical Triassic taxa appear. This interval of contemporaneous stepwise extinction and recovery resulted in an actual increase in spore-pollen taxa diversity during the earliest Triassic. The estimated average sedimentation rate indicates that the 24 m sampling gap that separates the last Permian assemblage from the first Triassic one represents ca 96 000 years, and that the continued stepwise extinction and recovery lasted for ca 325 000 years. In the aftermath of the end-Permian crisis only 27% of the typical Permian spores and pollen, that were present from the lower McKinnon Member in the Prince Charles Mountains survived to the late Induan, but by then the biodiversity had only decreased by less than 10%. Comparisons of Gondwanan palynological and lithological data indicate that intense global warming had already begun in the Permian, and that high latitude Gondwana areas such as the PCMs, were affected later than areas to the north and west. They also suggest that the end-Permian crisis affected the various Gondwana regions in different ways, but that the end result appears to have been a more equable, sub-humid to semi-arid, and less seasonal climate across southern Gondwana.
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Nine palynological intervals, A-I in ascending order, are recognised in the Carboniferous succession of the well 7120/2-1 on the Loppa High in the western Barents Sea.Within the Billefjorden Group intervals A-E are correlated with the... more
Nine palynological intervals, A-I in ascending order, are recognised in the Carboniferous succession of the well 7120/2-1 on the Loppa High in the western Barents Sea.Within the Billefjorden Group intervals A-E are correlated with the early Viséan to Serpukhovian Pu to TK Miospore Zones of western Europe. The known sedimentation break between the Billefjorden and Gipsdalen groups occurred in the Serpukhovian, as interval G of the lower part of the Gipsdalen Group is equivalent to the late Serpukhovian SO Miospore Zone. Lycospora pusilla and Densosporites spp. dominate these assemblages, indicating humid conditions. The topmost interval I correlates with early Moscovian palynofloras of the Arctic. It is at the oldest equivalent with the NJ Miospore Zone. Assemblages within this interval are dominated by the monosaccate pollen Florinites and Potonieisporites, with abundant taeniate and non-taeniate bisaccate pollen, indicating deposition under a dry climatic regime.
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The dinoflagellate cyst Lunnomidinium scaniense gen. et sp. nov. is present in the lower part of a thin sequence of Rhaetian sedimentary rocks exposed in the Lunnom Coal and Clay Pit in NW Scania, southern Sweden. It occurs in diverse,... more
The dinoflagellate cyst Lunnomidinium scaniense gen. et sp. nov. is present in the lower part of a thin sequence of Rhaetian sedimentary rocks exposed in the Lunnom Coal and Clay Pit in NW Scania, southern Sweden. It occurs in diverse, Rhaetian palynomorph assemblages, dominated by spores and pollen, but with rare specimens of the dinoflagellate cysts Rhaetogonyaulax rhaetica (Sarjeant) Loeblich and Loeblich 1968, Shublikodinium sp. and Beaumontella? caminuspina (Wall) Below 1987. Lunnomidinium scaniense is characterized by an epicystal {tAtItP} archeopyle, a large number of paraplates arranged in seven or eight latitudinal series, and intratabular ornamentation
in some but not all of the paraplate series. Thus, L. scaniense is assignable to the family Suessiaceae. Lunnomidinium scaniense can be subdivided into two different morphological varieties, based on the autophragm ornamentation and cyst size.
in some but not all of the paraplate series. Thus, L. scaniense is assignable to the family Suessiaceae. Lunnomidinium scaniense can be subdivided into two different morphological varieties, based on the autophragm ornamentation and cyst size.
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Abstract The Triassic-Jurassic boundary (TJ; 201.6 Ma) marks one of the so called Big Five mass-extinction events that may have led to the extinction of more than 80% of all marine invertebrates. The extinction of marine and terrestrial... more
Abstract The Triassic-Jurassic boundary (TJ; 201.6 Ma) marks one of the so called Big Five mass-extinction events that may have led to the extinction of more than 80% of all marine invertebrates. The extinction of marine and terrestrial biota is increasingly linked to the ...
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Abstract In the Upper Triassic Chinle Formation of northern New Mexico a diverse suite of basal dinosauromorphs and dinosaurs co-existed for many millions of years. Faunas with both these basal forms and dinosaurs, and basal archosaurs... more
Abstract In the Upper Triassic Chinle Formation of northern New Mexico a diverse suite of basal dinosauromorphs and dinosaurs co-existed for many millions of years. Faunas with both these basal forms and dinosaurs, and basal archosaurs have so far only been ...
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DOAJ Directory of Open Access Journals, SPARC Europe Award 2009 English. Free, full text, quality controlled scientific and scholarly journals, covering all subjects and many languages. ...
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The dinosaur fauna of the palynologically dated lower Berriasian Skyttegård Member of the Rabekke Formation on the Baltic island of Bornholm, Denmark, is represented by isolated tooth crowns. The assemblage is restricted to small... more
The dinosaur fauna of the palynologically dated lower Berriasian Skyttegård Member of the Rabekke Formation on the Baltic island of Bornholm, Denmark, is represented by isolated tooth crowns. The assemblage is restricted to small maniraptoran theropods, assigned to the Dromaeosauridae incertae sedis and Maniraptora incertae sedis. The dromaeosaurid teeth are characterized by their labiolingually compressed and distally curved crowns that are each equipped with a lingually flexed mesial carina and a distinctly denticulated distal cutting edge. A
morphologically aberrant tooth crown (referred to as Maniraptora incertae sedis) has triangular denticles of uneven width, a feature occasionally found in Upper Cretaceous hesperornithiform toothed diving birds, but also in premaxillary teeth of the velociraptorine Nuthetes from the Lower Cretaceous of England.
morphologically aberrant tooth crown (referred to as Maniraptora incertae sedis) has triangular denticles of uneven width, a feature occasionally found in Upper Cretaceous hesperornithiform toothed diving birds, but also in premaxillary teeth of the velociraptorine Nuthetes from the Lower Cretaceous of England.
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The palynological content of randomly collected sedimentary rock clasts from the till on the south-east slope of the Basen nunatak in northern Vestfjella in western Dronning Maud Land indicate that these sedimentary rocks were derived... more
The palynological content of randomly collected sedimentary rock clasts from the till on the south-east slope of the Basen nunatak in northern Vestfjella in western Dronning Maud Land indicate that these sedimentary rocks were derived from strata of Middle Permian age. The palynological content and preservation is similar to palynofloras described from the sedimentary rocks that crop out at the Fossilryggen nunatak to the south-east, therefore, it seems likely that the Fossilryggen area represents the source of the sedimentary rock samples in the Basen till. This is further supported by known ice flow directions obtained from striations and clast fabric measurements in the area.
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Permineralized sporangia from Late Permian sediments of the Amery Group in the Prince Charles Mountains, East Antarctica, are assigned to Arberiella sp. cf. A. africana Pant and Nautiyal. These sporangia contain between 2000 and 3000... more
Permineralized sporangia from Late Permian sediments of the Amery Group in the Prince Charles Mountains, East Antarctica, are assigned to Arberiella sp. cf. A. africana Pant and Nautiyal. These sporangia contain between 2000 and 3000 taeniate, saccate pollen grains that are predominantly haploxylonoid bisaccate and referable to the palynotaxon Protohaploxypinus limpidus (Balme and Hennelly) Balme and Playford. However, the sporangia also contain greater than 4% of diploxylonoid bisaccate forms comparable to Striatopodocarpidites cancellatus (Balme and Hennelly) Hart 1963, together with sporadic monosaccate and trisaccate grains that, if found dispersed, would be assigned to several different pollen form genera. Morphometric analysis of in situ bisaccate pollen grains and taeniate bisaccate pollen in the dispersed palynoflora indicates that in situ grains occupy only the smaller end of the total size range. The tendency for in situ grains to cluster into two different size groups may reflect differential predispersal expansion of the corpus. The in situ pollen grains are variable in most qualitative and quantitative features used for taxonomic discrimination of dispersed taeniate bisaccate pollen, and this may lead to unreliable estimates of Late Permian floristic diversity if an overly restrictive species delimitation scheme is used.
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Publikationsansicht. 5341164. Late Palaeozoic palynology of western Dronning Maud Land, Antarctica / (1994). Lindström, Sofie. Abstract. Summary and review of Thesis (doctoral)--Lund University, 1994.. Includes bibliographical references... more
Publikationsansicht. 5341164. Late Palaeozoic palynology of western Dronning Maud Land, Antarctica / (1994). Lindström, Sofie. Abstract. Summary and review of Thesis (doctoral)--Lund University, 1994.. Includes bibliographical references (p. 27-30). Details der Publikation. ...
Ninety-one samples from three sections at Fossilryggen in the Vestfjella mountain range of Antarctica have been investigated palynologically. Sixty-six taxa are recognized in forty-eight productive samples from two of these sections: the... more
Ninety-one samples from three sections at Fossilryggen in the Vestfjella mountain range of Antarctica have been investigated palynologically. Sixty-six taxa are recognized in forty-eight productive samples from two of these sections: the southern section at Fossilryggen and the NW Nunatak section. The palynomorphs have been subjected to contact metamorphosis and display various grades of thermal maturity, ranging in color from light brown to black. They also display various degrees of preservation. Among the spores found are Didecitriletes ericianus, D. uncinatus, Dictyotriletes labyrinthicus (Anderson) comb. nov., Horriditriletes filiformis, Microbaculispora trisina, M. villosa, Osmundacidites wellmanii and Gondisporites raniganjensis. Taeniate and non-taeniate bisaccates are dominant and include Scheuringipollenites ovatus, S. maximus, Vitreisporites pallidus, Protohaploxypinus spp., Striatopodocarpidites spp. and Guttulapollenites hannonicus. Other pollen-grains present are Weylandites lucifer, Praecolpatites sinuosus and Bascanisporites undosus. Although the sections have been interpreted as being deposited in a near-shore marine environment, acritarchs and algae are rare in these assemblages and include the forms Peltacystiavenosa, P. monile, Cymatiosphaera gondwanensis, Leiosphaeridia sp. B and Brazilea scissa. These assemblages are regarded as being of Late Permian age, Kazanian to Tatarian, and are correlated with Upper Stage 5 palynofloras in Australia, and with similar assemblages in Africa and India. Correlations are also made with other Late Permian palynofloras within Antarctica.
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The Permian-Triassic boundary within the Amery Group of the Lambert Graben is placed at the contact between the Bainmedart Coal Measures and overlying Flagstone Bench Formation, based on the first regular Occurrence of Lunatisporites... more
The Permian-Triassic boundary within the Amery Group of the Lambert Graben is placed at the contact between the Bainmedart Coal Measures and overlying Flagstone Bench Formation, based on the first regular Occurrence of Lunatisporites pellucidus and the first appearance of Aratrisporites and Lepidopteris species. The Permian-Triassic boundary is marked by the extinction of glossopterid and cordaitalean gymnosperms, and by the disappearance or extreme decline of a range of gymnospermous and pteridophytic
palynomorph groups. Earliest Triassic macrofloras and palynofloras of the Flagstone Bench Formation are
dominated by peltasperms and lycophytes; corystosperms, conifers, and ferns become increasingly common elements of assemblages through the Lower Triassic part of the formation and dominate floras of the Upper Triassic strata. The sedimentary transition across this boundary is conformable but marked by a termination of coal deposits; overlying lowermost Triassic sediments contain only carbonaceous siltstones. Typical redbed facies are not developed until at least 100 m above the base of the Flagstone Bench Formation, in strata
containing ?Middle Triassic palynofloras. Across Gondwana the diachronous disappearance of coal deposits and appearance of red-beds is suggestive of a response to shifting climatic belts, resulting in progressively drier seasonal conditions at successively higher palaeolatitudes during the Late Permian to Middle Triassic. The abrupt and approximately synchronous replacement of plant groups at the Permian-Triassic boundary
suggests that factors independent of, or additional to, climate change were responsible for the turnover in terrestrial floras.
palynomorph groups. Earliest Triassic macrofloras and palynofloras of the Flagstone Bench Formation are
dominated by peltasperms and lycophytes; corystosperms, conifers, and ferns become increasingly common elements of assemblages through the Lower Triassic part of the formation and dominate floras of the Upper Triassic strata. The sedimentary transition across this boundary is conformable but marked by a termination of coal deposits; overlying lowermost Triassic sediments contain only carbonaceous siltstones. Typical redbed facies are not developed until at least 100 m above the base of the Flagstone Bench Formation, in strata
containing ?Middle Triassic palynofloras. Across Gondwana the diachronous disappearance of coal deposits and appearance of red-beds is suggestive of a response to shifting climatic belts, resulting in progressively drier seasonal conditions at successively higher palaeolatitudes during the Late Permian to Middle Triassic. The abrupt and approximately synchronous replacement of plant groups at the Permian-Triassic boundary
suggests that factors independent of, or additional to, climate change were responsible for the turnover in terrestrial floras.