Michael Streng | Uppsala University (original) (raw)
Papers by Michael Streng
Volcanic pyroclasts of small size, such as lapilli and small pumice stones, are widely used in ag... more Volcanic pyroclasts of small size, such as lapilli and small pumice stones, are widely used in agriculture, gardening, and for pot plants as natural inorganic mulch. The technique of using pyroclasts to enhance topsoil stems from the eighteenth century, and specifically from the ad 1730-1736 eruption on Lanzarote. Critical observations on plant development during and after the eruption showed that the vegetation died when buried under a thick layer of lapilli, but grew vigorously when covered thinly. While the agriculture of Lanzarote was restricted to cereals before the eruption, it diversified to many kinds of fruit and vegetables afterwards, including the production of the famous Malvasía wines in the Canaries. The population of Lanzarote doubled in the years after the eruption, from about 5000 in 1730 to near 10 000 in 1768, predominantly as a result of the higher agricultural productivity. This outcome led to widespread use of lapilli and pumice fragments throughout the islands and eventually the rest of the globe. Lapilli and pumice provide vesicle space for moisture to be retained longer within the planting soil, which can create an environment for micro-bacteria to thrive in. Through this route, nutrients from volcanic matter are transported into the surrounding soil where they become available to plant life. The detailed processes that operate within the pyroclasts are less well understood, such as the breakdown of nutrients from the rock matrix and transport into the soil by biological action. Further studies promise significant potential to optimize future agricultural efforts, particularly in otherwise arid areas of the globe.
Acta Palaeontologica Polonica, 2021
Bulk sampling of middle Cambrian carbonate units in the lower Burgess Shale Formation (Wuliuan) a... more Bulk sampling of middle Cambrian carbonate units in the lower Burgess Shale Formation (Wuliuan) and the upper Wheeler Formation (Drumian) in Utah have yielded abundant silicified stenothecoids. Previously unreported from the Burgess Shale, stenothecoids discovered include at least two species: Stenothecoides cf. elongata and Stenothecoides rasettii sp. nov. The Utah material is assigned to Stenothecoides elongata. The new stenothecoid material confirms some earlier observations including a set of interior grooves and ridges forming nested chevrons across the midline and a finer set disposed around the interior shell margin. The chevroned grooves are interpreted here as mantle canals and the peripheral furrows as setal grooves. A prominent boss occurs at the valve apex in both valves. An apparent socket receiving the boss in the opposite valve described in earlier studies we show to be an artefact of preservation. Consequently, the bosses were juxtaposed when the valves were conjoine...
The distribution of calcareous dinoflagellates has been analysed for the Maastrichtian-Miocene in... more The distribution of calcareous dinoflagellates has been analysed for the Maastrichtian-Miocene interval of Ocean Drilling Project Hole 689B (Maud Rise, Weddell Sea). The investigation thus represents a primary evaluation of the long-term evolution in high-latitude calcareous dinoflagellate assemblages during the transition from a relatively warm Late Cretaceous to a cold Neogene climate. Major assemblage changes during this interval occurred in characteristic steps: (1) an increase in relative abundance of tangentially structured species - particularly Operculodinella operculata - at the Cretaceous/Tertiary boundary; (2) a diversity decrease and several first and last appearances across the Middle-Late Eocene boundary, possibly attributed to increased climate cooling; (3) a diversity decrease associated with the dominance of Calciodinellum levantinum in the late Early Oligocene; (4) the reappearance and dominance of Pirumella edgarii in the Early Miocene, probably reflecting a warmi...
'Ovatoryctocara granulata' Chernysheva 1962, a key trilobite in discussions concerning in... more 'Ovatoryctocara granulata' Chernysheva 1962, a key trilobite in discussions concerning intercontinental correlation and the placement of the Cambrian Series 2-Series 3 boundary, occurs together with more than 60 other species in a fossil assemblage from the Henson Gletscher Formation of Londal, Peary Land, North Greenland. Most taxa are described from acid residues in which diverse protoconodonts, helcionellid molluscs and hyoliths occur together with linguliformean brachiopods, bradoriids and other fossils. Recognition of an earlier First Appearance Datum for 'O. granulata' in Londal consolidates the biostratigraphic relationship between the assemblage and other partly co-occurring trilobites valuable for correlation within Laurentia and beyond. The assemblage can be correlated with the 'Ovatoryctocara' Biozone, the basal biozone of the Molodian Stage in the Republic of Sakha (Yakutia, north-eastern Siberia), proposed as the earliest stage of Cambrian Series 3. New taxa are 'Tulenicornus'? 'Frykmani' sp. nov., 'Conotheca hensoni' sp. nov., 'Capitoconus borealis' sp. nov., 'Hipponicharion pearylandica' sp. nov. and 'Liangshanella'? 'nivalis' sp. nov.
of a new type of shell structure within the organophosphatic
Journal of Paleontology, 2015
Circum-Laurentian middle Cambrian (Cambrian Series 3) deposits in Greenland and British Columbia ... more Circum-Laurentian middle Cambrian (Cambrian Series 3) deposits in Greenland and British Columbia yield a new hipponicharionid bradoriid arthropod, Flumenoglacies n. gen., characterized by a comarginal, ramp-like structure which is crested by a continuous lobe. The narrow lobe is the result of the medial fusion of anterior and posterior lobes, seemingly a recurrent theme in hipponicharionid evolution. The type species, F. groenlandica n. sp., is described from the Ekspedition Brae Formation (Drumian Stage) of Peary Land but the description of two unnamed species from slightly older middle Cambrian strata of the Stephen Formation of British Columbia provides additional evidence for the wide distribution of Small Shelly Faunas during the Cambrian.
GFF, 2013
The late Llandovery graptolite fauna of the Retiolites Shales on Kinnekulle Mountain in the provi... more The late Llandovery graptolite fauna of the Retiolites Shales on Kinnekulle Mountain in the province of Västergötland has long been known but never illustrated or studied in detail. New collections of graptolites from an interval at the very top of the exposed succession confirm previous reports of cyrtograptids, which make the shales on Kinnekulle the youngest preserved Palaeozoic rocks in the area. The co-occurrence of Oktavites spiralis and Cyrtograptus lapworthi constrains the strata to the lower lapworthi Biozone of the upper Telychian. The associated graptolite fauna comprises numerous monograptids and Retiolites angustidens as well as Cyrtograptus kinnekullensis n. sp., characterised by its open coiling and the presence of a second-order cladium on the second thecal cladium. This early occurrence of a cyrtograptid species with a second-order cladium on Baltica matches evolutionary patterns observed in Laurentia, suggesting that the ability to grow cladia of both first and higher order evolved approximately, synchronously and at the very beginning of cyrtograptid evolution.
Bulletin of Geosciences, 2014
Boreholes in mineralized shells are a widely recognized form of predation throughout the Phaneroz... more Boreholes in mineralized shells are a widely recognized form of predation throughout the Phanerozoic. In fact, such borings are as old as the first mineralized shells dating back to the Ediacaran. ...
Evidence for pedicle sizes and pedicle morphologies of fossil linguliform brachiopods is scarce a... more Evidence for pedicle sizes and pedicle morphologies of fossil linguliform brachiopods is scarce and mainly restricted to exceptionally preserved specimens of fossil Lagerstatten. Recently described ...
The Paracuellos Group is the oldest sedimentary sequence of the Iberian Chains in north-east Spai... more The Paracuellos Group is the oldest sedimentary sequence of the Iberian Chains in north-east Spain. The group is subdivided into three formation which are, in stratigraphic order, the Sestrica Form ...
The middle Cambrian Stephen Formation of the western Canadian Rocky Mountains might be best known... more The middle Cambrian Stephen Formation of the western Canadian Rocky Mountains might be best known for including the famous Burgess Shale with its exceptionally preserved fossils. Likewise remarkable is, however, its depositional setting, which was characterized by the presence of a submarine cliff that divided the environment into a deeper, basinal and a shallower part. This division, caused by the so called Cathedral Escarpment, resulted in the development of two distinct regional expressions of the formation, a thick, i.e., basinal, and a thin, i.e., shallower, one. Whereas previous paleontological studies of the Stephen Formation mainly focused on the exceptional preserved fauna and its macroscopic fossils, we present here the first systematic study of the microfossil content of the limestone horizons occurring throughout the formation. Five sections of the thin and thick Stephen Formation have been measured and sampled in Yoho and Kootenay National Park. In total, samples from o...
Long-term changes vs. short-term changes in calcareous dinoflagellates - examples from the Tertiary.
Geological Magazine, 2021
The two major structural elements of the Iberian Chains, the Datos and Jarque thrust faults, have... more The two major structural elements of the Iberian Chains, the Datos and Jarque thrust faults, have been described as occurring in proximity in the area around the village of Codos. The purported Jarque fault corresponds to the axial plane of an anticline known as the Codos anticline, which exposes the oldest stratigraphic unit in this area, i.e. the Codos Bed, a limestone bed bearing skeletal fossils of putative Ediacaran or earliest Cambrian age. Details of the geology of the area and the age of the known fossils are poorly understood or not universally agreed upon. New investigations in the anticline revealed the presence of a normal fault, introduced as the Codos fault, which cross-cuts the course of the alleged Jarque fault. The vertical displacement along the axial plane of the anticline appears to be insignificant, challenging the traditional interpretation of the plane as an equivalent of the Jarque thrust fault. Reinvestigation of the Codos Bed revealed previously unknown ske...
A new species of the genus Cyrtograptus from the late Llandovery of southern Sweden (Vastergotlan... more A new species of the genus Cyrtograptus from the late Llandovery of southern Sweden (Vastergotland) is presented. The new species has been found near the top of Kinnekulle (Hogkullen) in the Retiolites Shales, which are part of the lapworthi zone (late Telychian). Although it resembles the coeval C. lapworthi in appearance, a detailed comparison of the type material of C. lapworthi revealed distinct differences: the new species is more openly coiled in the proximal part, has a larger Two Thecae Repeat Distance (2TRD), and, most significantly, bears a second order cladium. Second order cladia are unknown from C. lapworthi. The new species is also compared with other species of Cyrtograptus that are characterized by second order cladia, such as the cotemporaneous C. laqueus and the slightly younger C. insectus (insectus zone; latest Telychian). However, C. laqueus differs from the new species in having a lower number of thecae separating the cladia, and also by the appearance of its p...
Volcanic pyroclasts of small size, such as lapilli and small pumice stones, are widely used in ag... more Volcanic pyroclasts of small size, such as lapilli and small pumice stones, are widely used in agriculture, gardening, and for pot plants as natural inorganic mulch. The technique of using pyroclasts to enhance topsoil stems from the eighteenth century, and specifically from the ad 1730-1736 eruption on Lanzarote. Critical observations on plant development during and after the eruption showed that the vegetation died when buried under a thick layer of lapilli, but grew vigorously when covered thinly. While the agriculture of Lanzarote was restricted to cereals before the eruption, it diversified to many kinds of fruit and vegetables afterwards, including the production of the famous Malvasía wines in the Canaries. The population of Lanzarote doubled in the years after the eruption, from about 5000 in 1730 to near 10 000 in 1768, predominantly as a result of the higher agricultural productivity. This outcome led to widespread use of lapilli and pumice fragments throughout the islands and eventually the rest of the globe. Lapilli and pumice provide vesicle space for moisture to be retained longer within the planting soil, which can create an environment for micro-bacteria to thrive in. Through this route, nutrients from volcanic matter are transported into the surrounding soil where they become available to plant life. The detailed processes that operate within the pyroclasts are less well understood, such as the breakdown of nutrients from the rock matrix and transport into the soil by biological action. Further studies promise significant potential to optimize future agricultural efforts, particularly in otherwise arid areas of the globe.
Acta Palaeontologica Polonica, 2021
Bulk sampling of middle Cambrian carbonate units in the lower Burgess Shale Formation (Wuliuan) a... more Bulk sampling of middle Cambrian carbonate units in the lower Burgess Shale Formation (Wuliuan) and the upper Wheeler Formation (Drumian) in Utah have yielded abundant silicified stenothecoids. Previously unreported from the Burgess Shale, stenothecoids discovered include at least two species: Stenothecoides cf. elongata and Stenothecoides rasettii sp. nov. The Utah material is assigned to Stenothecoides elongata. The new stenothecoid material confirms some earlier observations including a set of interior grooves and ridges forming nested chevrons across the midline and a finer set disposed around the interior shell margin. The chevroned grooves are interpreted here as mantle canals and the peripheral furrows as setal grooves. A prominent boss occurs at the valve apex in both valves. An apparent socket receiving the boss in the opposite valve described in earlier studies we show to be an artefact of preservation. Consequently, the bosses were juxtaposed when the valves were conjoine...
The distribution of calcareous dinoflagellates has been analysed for the Maastrichtian-Miocene in... more The distribution of calcareous dinoflagellates has been analysed for the Maastrichtian-Miocene interval of Ocean Drilling Project Hole 689B (Maud Rise, Weddell Sea). The investigation thus represents a primary evaluation of the long-term evolution in high-latitude calcareous dinoflagellate assemblages during the transition from a relatively warm Late Cretaceous to a cold Neogene climate. Major assemblage changes during this interval occurred in characteristic steps: (1) an increase in relative abundance of tangentially structured species - particularly Operculodinella operculata - at the Cretaceous/Tertiary boundary; (2) a diversity decrease and several first and last appearances across the Middle-Late Eocene boundary, possibly attributed to increased climate cooling; (3) a diversity decrease associated with the dominance of Calciodinellum levantinum in the late Early Oligocene; (4) the reappearance and dominance of Pirumella edgarii in the Early Miocene, probably reflecting a warmi...
'Ovatoryctocara granulata' Chernysheva 1962, a key trilobite in discussions concerning in... more 'Ovatoryctocara granulata' Chernysheva 1962, a key trilobite in discussions concerning intercontinental correlation and the placement of the Cambrian Series 2-Series 3 boundary, occurs together with more than 60 other species in a fossil assemblage from the Henson Gletscher Formation of Londal, Peary Land, North Greenland. Most taxa are described from acid residues in which diverse protoconodonts, helcionellid molluscs and hyoliths occur together with linguliformean brachiopods, bradoriids and other fossils. Recognition of an earlier First Appearance Datum for 'O. granulata' in Londal consolidates the biostratigraphic relationship between the assemblage and other partly co-occurring trilobites valuable for correlation within Laurentia and beyond. The assemblage can be correlated with the 'Ovatoryctocara' Biozone, the basal biozone of the Molodian Stage in the Republic of Sakha (Yakutia, north-eastern Siberia), proposed as the earliest stage of Cambrian Series 3. New taxa are 'Tulenicornus'? 'Frykmani' sp. nov., 'Conotheca hensoni' sp. nov., 'Capitoconus borealis' sp. nov., 'Hipponicharion pearylandica' sp. nov. and 'Liangshanella'? 'nivalis' sp. nov.
of a new type of shell structure within the organophosphatic
Journal of Paleontology, 2015
Circum-Laurentian middle Cambrian (Cambrian Series 3) deposits in Greenland and British Columbia ... more Circum-Laurentian middle Cambrian (Cambrian Series 3) deposits in Greenland and British Columbia yield a new hipponicharionid bradoriid arthropod, Flumenoglacies n. gen., characterized by a comarginal, ramp-like structure which is crested by a continuous lobe. The narrow lobe is the result of the medial fusion of anterior and posterior lobes, seemingly a recurrent theme in hipponicharionid evolution. The type species, F. groenlandica n. sp., is described from the Ekspedition Brae Formation (Drumian Stage) of Peary Land but the description of two unnamed species from slightly older middle Cambrian strata of the Stephen Formation of British Columbia provides additional evidence for the wide distribution of Small Shelly Faunas during the Cambrian.
GFF, 2013
The late Llandovery graptolite fauna of the Retiolites Shales on Kinnekulle Mountain in the provi... more The late Llandovery graptolite fauna of the Retiolites Shales on Kinnekulle Mountain in the province of Västergötland has long been known but never illustrated or studied in detail. New collections of graptolites from an interval at the very top of the exposed succession confirm previous reports of cyrtograptids, which make the shales on Kinnekulle the youngest preserved Palaeozoic rocks in the area. The co-occurrence of Oktavites spiralis and Cyrtograptus lapworthi constrains the strata to the lower lapworthi Biozone of the upper Telychian. The associated graptolite fauna comprises numerous monograptids and Retiolites angustidens as well as Cyrtograptus kinnekullensis n. sp., characterised by its open coiling and the presence of a second-order cladium on the second thecal cladium. This early occurrence of a cyrtograptid species with a second-order cladium on Baltica matches evolutionary patterns observed in Laurentia, suggesting that the ability to grow cladia of both first and higher order evolved approximately, synchronously and at the very beginning of cyrtograptid evolution.
Bulletin of Geosciences, 2014
Boreholes in mineralized shells are a widely recognized form of predation throughout the Phaneroz... more Boreholes in mineralized shells are a widely recognized form of predation throughout the Phanerozoic. In fact, such borings are as old as the first mineralized shells dating back to the Ediacaran. ...
Evidence for pedicle sizes and pedicle morphologies of fossil linguliform brachiopods is scarce a... more Evidence for pedicle sizes and pedicle morphologies of fossil linguliform brachiopods is scarce and mainly restricted to exceptionally preserved specimens of fossil Lagerstatten. Recently described ...
The Paracuellos Group is the oldest sedimentary sequence of the Iberian Chains in north-east Spai... more The Paracuellos Group is the oldest sedimentary sequence of the Iberian Chains in north-east Spain. The group is subdivided into three formation which are, in stratigraphic order, the Sestrica Form ...
The middle Cambrian Stephen Formation of the western Canadian Rocky Mountains might be best known... more The middle Cambrian Stephen Formation of the western Canadian Rocky Mountains might be best known for including the famous Burgess Shale with its exceptionally preserved fossils. Likewise remarkable is, however, its depositional setting, which was characterized by the presence of a submarine cliff that divided the environment into a deeper, basinal and a shallower part. This division, caused by the so called Cathedral Escarpment, resulted in the development of two distinct regional expressions of the formation, a thick, i.e., basinal, and a thin, i.e., shallower, one. Whereas previous paleontological studies of the Stephen Formation mainly focused on the exceptional preserved fauna and its macroscopic fossils, we present here the first systematic study of the microfossil content of the limestone horizons occurring throughout the formation. Five sections of the thin and thick Stephen Formation have been measured and sampled in Yoho and Kootenay National Park. In total, samples from o...
Long-term changes vs. short-term changes in calcareous dinoflagellates - examples from the Tertiary.
Geological Magazine, 2021
The two major structural elements of the Iberian Chains, the Datos and Jarque thrust faults, have... more The two major structural elements of the Iberian Chains, the Datos and Jarque thrust faults, have been described as occurring in proximity in the area around the village of Codos. The purported Jarque fault corresponds to the axial plane of an anticline known as the Codos anticline, which exposes the oldest stratigraphic unit in this area, i.e. the Codos Bed, a limestone bed bearing skeletal fossils of putative Ediacaran or earliest Cambrian age. Details of the geology of the area and the age of the known fossils are poorly understood or not universally agreed upon. New investigations in the anticline revealed the presence of a normal fault, introduced as the Codos fault, which cross-cuts the course of the alleged Jarque fault. The vertical displacement along the axial plane of the anticline appears to be insignificant, challenging the traditional interpretation of the plane as an equivalent of the Jarque thrust fault. Reinvestigation of the Codos Bed revealed previously unknown ske...
A new species of the genus Cyrtograptus from the late Llandovery of southern Sweden (Vastergotlan... more A new species of the genus Cyrtograptus from the late Llandovery of southern Sweden (Vastergotland) is presented. The new species has been found near the top of Kinnekulle (Hogkullen) in the Retiolites Shales, which are part of the lapworthi zone (late Telychian). Although it resembles the coeval C. lapworthi in appearance, a detailed comparison of the type material of C. lapworthi revealed distinct differences: the new species is more openly coiled in the proximal part, has a larger Two Thecae Repeat Distance (2TRD), and, most significantly, bears a second order cladium. Second order cladia are unknown from C. lapworthi. The new species is also compared with other species of Cyrtograptus that are characterized by second order cladia, such as the cotemporaneous C. laqueus and the slightly younger C. insectus (insectus zone; latest Telychian). However, C. laqueus differs from the new species in having a lower number of thecae separating the cladia, and also by the appearance of its p...