The Experts below are selected from a list of 31110 Experts worldwide ranked by ideXlab platform
Sarah Noben - One of the best experts on this subject based on the ideXlab platform.
-
biogeography of the Gondwanan tree fern family dicksoniaceae a tale of vicariance dispersal and extinction
Journal of Biogeography, 2017Co-Authors: Sarah Noben, Michael Kessler, Dietmar Quandt, Anna Weigand, Susann Wicke, Michael Krug, Marcus LehnertAbstract:Aim Are the disjunct distributions of ancient lineages on continents in the Southern Hemisphere determined by vicariance following the Gondwanan tectonic breakup or recent long-distance dispersal? We traced the historical biogeography of the tree fern family Dicksoniaceae (145 Ma), which has a typical Gondwanan distribution, to test for vicariance or recent long-distance dispersal. Location Subtropical, tropical and temperate forests of the Southern Hemisphere. Methods We performed a molecular phylogenetic study of the family based on four chloroplast markers using Bayesian and maximum likelihood inference. Spore fossils served to calibrate the dating of the phylogeny using beast. The historical biogeography of the family was traced via an ancestral area reconstruction using a maximum likelihood approach. Results We corroborated the genus Dicksonia (widespread) as sister to Lophosoria (Neotropical), with Calochlaena (Palaeotropical) as sister to both. The phylogenetic splits between the genera predate the break-up of Gondwana. Lophosoria is currently restricted to America but fossils document extinct populations in Australia, Tasmania and Antarctica. Within Dicksonia, we found three clades which separated 55–25 Ma: one including species from New Caledonia, New Zealand and Fiji; another containing species from the Neotropics as well as southern Australia and New Zealand; and one with species from northern Australia to the Philippines and Sumatra. Vicariance and ancient long-distance dispersal can equally explain the occurrence of these three clades on different tectonic units of Gondwana. Other geographical disjunctions, for example, between Australia and Malesia, are more recent (15–3 Ma) and inferred to be the result of long-distance dispersal. The combination of fossil evidence and island endemics whose ages predate the ages of the islands point to substantial extinction in the genus. Main conclusions The biogeographical history of the family Dicksoniaceae, and especially of Dicksonia itself, appears to have involved a much more dynamic interplay of vicariance, dispersal and extinction than inferred from current distributions alone. Dicksonia is one of the few biogeographical Gondwanan floristic elements whose current distribution can at least partly be linked to plate tectonic events.
-
Biogeography of the Gondwanan tree fern family Dicksoniaceae—A tale of vicariance, dispersal and extinction
Journal of Biogeography, 2017Co-Authors: Sarah Noben, Michael Kessler, Dietmar Quandt, Anna Weigand, Susann Wicke, Michael Krug, Marcus LehnertAbstract:Aim Are the disjunct distributions of ancient lineages on continents in the Southern Hemisphere determined by vicariance following the Gondwanan tectonic breakup or recent long-distance dispersal? We traced the historical biogeography of the tree fern family Dicksoniaceae (145 Ma), which has a typical Gondwanan distribution, to test for vicariance or recent long-distance dispersal. Location Subtropical, tropical and temperate forests of the Southern Hemisphere. Methods We performed a molecular phylogenetic study of the family based on four chloroplast markers using Bayesian and maximum likelihood inference. Spore fossils served to calibrate the dating of the phylogeny using beast. The historical biogeography of the family was traced via an ancestral area reconstruction using a maximum likelihood approach. Results We corroborated the genus Dicksonia (widespread) as sister to Lophosoria (Neotropical), with Calochlaena (Palaeotropical) as sister to both. The phylogenetic splits between the genera predate the break-up of Gondwana. Lophosoria is currently restricted to America but fossils document extinct populations in Australia, Tasmania and Antarctica. Within Dicksonia, we found three clades which separated 55–25 Ma: one including species from New Caledonia, New Zealand and Fiji; another containing species from the Neotropics as well as southern Australia and New Zealand; and one with species from northern Australia to the Philippines and Sumatra. Vicariance and ancient long-distance dispersal can equally explain the occurrence of these three clades on different tectonic units of Gondwana. Other geographical disjunctions, for example, between Australia and Malesia, are more recent (15–3 Ma) and inferred to be the result of long-distance dispersal. The combination of fossil evidence and island endemics whose ages predate the ages of the islands point to substantial extinction in the genus. Main conclusions The biogeographical history of the family Dicksoniaceae, and especially of Dicksonia itself, appears to have involved a much more dynamic interplay of vicariance, dispersal and extinction than inferred from current distributions alone. Dicksonia is one of the few biogeographical Gondwanan floristic elements whose current distribution can at least partly be linked to plate tectonic events.
Marcus Lehnert - One of the best experts on this subject based on the ideXlab platform.
-
biogeography of the Gondwanan tree fern family dicksoniaceae a tale of vicariance dispersal and extinction
Journal of Biogeography, 2017Co-Authors: Sarah Noben, Michael Kessler, Dietmar Quandt, Anna Weigand, Susann Wicke, Michael Krug, Marcus LehnertAbstract:Aim Are the disjunct distributions of ancient lineages on continents in the Southern Hemisphere determined by vicariance following the Gondwanan tectonic breakup or recent long-distance dispersal? We traced the historical biogeography of the tree fern family Dicksoniaceae (145 Ma), which has a typical Gondwanan distribution, to test for vicariance or recent long-distance dispersal. Location Subtropical, tropical and temperate forests of the Southern Hemisphere. Methods We performed a molecular phylogenetic study of the family based on four chloroplast markers using Bayesian and maximum likelihood inference. Spore fossils served to calibrate the dating of the phylogeny using beast. The historical biogeography of the family was traced via an ancestral area reconstruction using a maximum likelihood approach. Results We corroborated the genus Dicksonia (widespread) as sister to Lophosoria (Neotropical), with Calochlaena (Palaeotropical) as sister to both. The phylogenetic splits between the genera predate the break-up of Gondwana. Lophosoria is currently restricted to America but fossils document extinct populations in Australia, Tasmania and Antarctica. Within Dicksonia, we found three clades which separated 55–25 Ma: one including species from New Caledonia, New Zealand and Fiji; another containing species from the Neotropics as well as southern Australia and New Zealand; and one with species from northern Australia to the Philippines and Sumatra. Vicariance and ancient long-distance dispersal can equally explain the occurrence of these three clades on different tectonic units of Gondwana. Other geographical disjunctions, for example, between Australia and Malesia, are more recent (15–3 Ma) and inferred to be the result of long-distance dispersal. The combination of fossil evidence and island endemics whose ages predate the ages of the islands point to substantial extinction in the genus. Main conclusions The biogeographical history of the family Dicksoniaceae, and especially of Dicksonia itself, appears to have involved a much more dynamic interplay of vicariance, dispersal and extinction than inferred from current distributions alone. Dicksonia is one of the few biogeographical Gondwanan floristic elements whose current distribution can at least partly be linked to plate tectonic events.
-
Biogeography of the Gondwanan tree fern family Dicksoniaceae—A tale of vicariance, dispersal and extinction
Journal of Biogeography, 2017Co-Authors: Sarah Noben, Michael Kessler, Dietmar Quandt, Anna Weigand, Susann Wicke, Michael Krug, Marcus LehnertAbstract:Aim Are the disjunct distributions of ancient lineages on continents in the Southern Hemisphere determined by vicariance following the Gondwanan tectonic breakup or recent long-distance dispersal? We traced the historical biogeography of the tree fern family Dicksoniaceae (145 Ma), which has a typical Gondwanan distribution, to test for vicariance or recent long-distance dispersal. Location Subtropical, tropical and temperate forests of the Southern Hemisphere. Methods We performed a molecular phylogenetic study of the family based on four chloroplast markers using Bayesian and maximum likelihood inference. Spore fossils served to calibrate the dating of the phylogeny using beast. The historical biogeography of the family was traced via an ancestral area reconstruction using a maximum likelihood approach. Results We corroborated the genus Dicksonia (widespread) as sister to Lophosoria (Neotropical), with Calochlaena (Palaeotropical) as sister to both. The phylogenetic splits between the genera predate the break-up of Gondwana. Lophosoria is currently restricted to America but fossils document extinct populations in Australia, Tasmania and Antarctica. Within Dicksonia, we found three clades which separated 55–25 Ma: one including species from New Caledonia, New Zealand and Fiji; another containing species from the Neotropics as well as southern Australia and New Zealand; and one with species from northern Australia to the Philippines and Sumatra. Vicariance and ancient long-distance dispersal can equally explain the occurrence of these three clades on different tectonic units of Gondwana. Other geographical disjunctions, for example, between Australia and Malesia, are more recent (15–3 Ma) and inferred to be the result of long-distance dispersal. The combination of fossil evidence and island endemics whose ages predate the ages of the islands point to substantial extinction in the genus. Main conclusions The biogeographical history of the family Dicksoniaceae, and especially of Dicksonia itself, appears to have involved a much more dynamic interplay of vicariance, dispersal and extinction than inferred from current distributions alone. Dicksonia is one of the few biogeographical Gondwanan floristic elements whose current distribution can at least partly be linked to plate tectonic events.
Anna Weigand - One of the best experts on this subject based on the ideXlab platform.
-
biogeography of the Gondwanan tree fern family dicksoniaceae a tale of vicariance dispersal and extinction
Journal of Biogeography, 2017Co-Authors: Sarah Noben, Michael Kessler, Dietmar Quandt, Anna Weigand, Susann Wicke, Michael Krug, Marcus LehnertAbstract:Aim Are the disjunct distributions of ancient lineages on continents in the Southern Hemisphere determined by vicariance following the Gondwanan tectonic breakup or recent long-distance dispersal? We traced the historical biogeography of the tree fern family Dicksoniaceae (145 Ma), which has a typical Gondwanan distribution, to test for vicariance or recent long-distance dispersal. Location Subtropical, tropical and temperate forests of the Southern Hemisphere. Methods We performed a molecular phylogenetic study of the family based on four chloroplast markers using Bayesian and maximum likelihood inference. Spore fossils served to calibrate the dating of the phylogeny using beast. The historical biogeography of the family was traced via an ancestral area reconstruction using a maximum likelihood approach. Results We corroborated the genus Dicksonia (widespread) as sister to Lophosoria (Neotropical), with Calochlaena (Palaeotropical) as sister to both. The phylogenetic splits between the genera predate the break-up of Gondwana. Lophosoria is currently restricted to America but fossils document extinct populations in Australia, Tasmania and Antarctica. Within Dicksonia, we found three clades which separated 55–25 Ma: one including species from New Caledonia, New Zealand and Fiji; another containing species from the Neotropics as well as southern Australia and New Zealand; and one with species from northern Australia to the Philippines and Sumatra. Vicariance and ancient long-distance dispersal can equally explain the occurrence of these three clades on different tectonic units of Gondwana. Other geographical disjunctions, for example, between Australia and Malesia, are more recent (15–3 Ma) and inferred to be the result of long-distance dispersal. The combination of fossil evidence and island endemics whose ages predate the ages of the islands point to substantial extinction in the genus. Main conclusions The biogeographical history of the family Dicksoniaceae, and especially of Dicksonia itself, appears to have involved a much more dynamic interplay of vicariance, dispersal and extinction than inferred from current distributions alone. Dicksonia is one of the few biogeographical Gondwanan floristic elements whose current distribution can at least partly be linked to plate tectonic events.
-
Biogeography of the Gondwanan tree fern family Dicksoniaceae—A tale of vicariance, dispersal and extinction
Journal of Biogeography, 2017Co-Authors: Sarah Noben, Michael Kessler, Dietmar Quandt, Anna Weigand, Susann Wicke, Michael Krug, Marcus LehnertAbstract:Aim Are the disjunct distributions of ancient lineages on continents in the Southern Hemisphere determined by vicariance following the Gondwanan tectonic breakup or recent long-distance dispersal? We traced the historical biogeography of the tree fern family Dicksoniaceae (145 Ma), which has a typical Gondwanan distribution, to test for vicariance or recent long-distance dispersal. Location Subtropical, tropical and temperate forests of the Southern Hemisphere. Methods We performed a molecular phylogenetic study of the family based on four chloroplast markers using Bayesian and maximum likelihood inference. Spore fossils served to calibrate the dating of the phylogeny using beast. The historical biogeography of the family was traced via an ancestral area reconstruction using a maximum likelihood approach. Results We corroborated the genus Dicksonia (widespread) as sister to Lophosoria (Neotropical), with Calochlaena (Palaeotropical) as sister to both. The phylogenetic splits between the genera predate the break-up of Gondwana. Lophosoria is currently restricted to America but fossils document extinct populations in Australia, Tasmania and Antarctica. Within Dicksonia, we found three clades which separated 55–25 Ma: one including species from New Caledonia, New Zealand and Fiji; another containing species from the Neotropics as well as southern Australia and New Zealand; and one with species from northern Australia to the Philippines and Sumatra. Vicariance and ancient long-distance dispersal can equally explain the occurrence of these three clades on different tectonic units of Gondwana. Other geographical disjunctions, for example, between Australia and Malesia, are more recent (15–3 Ma) and inferred to be the result of long-distance dispersal. The combination of fossil evidence and island endemics whose ages predate the ages of the islands point to substantial extinction in the genus. Main conclusions The biogeographical history of the family Dicksoniaceae, and especially of Dicksonia itself, appears to have involved a much more dynamic interplay of vicariance, dispersal and extinction than inferred from current distributions alone. Dicksonia is one of the few biogeographical Gondwanan floristic elements whose current distribution can at least partly be linked to plate tectonic events.
Robert Lopez - One of the best experts on this subject based on the ideXlab platform.
-
late ordovician early silurian continental collisional orogeny in southern mexico and its bearing on Gondwana laurentia connections
Geology, 1999Co-Authors: Fernando Ortegagutierrez, Mariano Eliasherrera, Margarita Reyessalas, Consuelo Maciasromo, Robert LopezAbstract:New zircon and monazite U-Pb data, tectonic mapping, and petrologic studies in key units of the Acatlan Complex show a previously undocumented phase of continental collision orogeny of Late Ordovician–Early Silurian age in southern Mexico. The event involved the partial eclogitization of oceanic lithosphere and continental crust, which traveled westward more than 200 km over siliciclastic metasedimentary rocks of the trench-forearc of an opposing continental margin. The overriding eastern margin was the Oaxaquia microplate attached to Gondwana, and the western overridden margin is considered to have been the eastern margin of Laurentia. This event, which we name the Acatecan orogeny, was roughly synchronous with the possible closure of Iapetus along the Appalachian margin, which involved, according to current models, either the docking of peri-Gondwanan terranes such as Avalonia and Carolina or the direct collision between Gondwana and Laurentia. The permanence of Oaxaquia in northwestern Gondwana until the end of the Silurian, as suggested by Tremadocian to Silurian marine faunas in the cover of Oaxaquia, is more consistent with the direct collision of Gondwana and Laurentia at the end of the Ordovician, forming the Acatlan Complex between.
-
Late Ordovician–Early Silurian continental collisional orogeny in southern Mexico and its bearing on Gondwana-Laurentia connections
Geology, 1999Co-Authors: Fernando Ortega-gutiérrez, Mariano Elías-herrera, Consuelo Macías-romo, Margarita Reyes-salas, Robert LopezAbstract:New zircon and monazite U-Pb data, tectonic mapping, and petrologic studies in key units of the Acatlan Complex show a previously undocumented phase of continental collision orogeny of Late Ordovician–Early Silurian age in southern Mexico. The event involved the partial eclogitization of oceanic lithosphere and continental crust, which traveled westward more than 200 km over siliciclastic metasedimentary rocks of the trench-forearc of an opposing continental margin. The overriding eastern margin was the Oaxaquia microplate attached to Gondwana, and the western overridden margin is considered to have been the eastern margin of Laurentia. This event, which we name the Acatecan orogeny, was roughly synchronous with the possible closure of Iapetus along the Appalachian margin, which involved, according to current models, either the docking of peri-Gondwanan terranes such as Avalonia and Carolina or the direct collision between Gondwana and Laurentia. The permanence of Oaxaquia in northwestern Gondwana until the end of the Silurian, as suggested by Tremadocian to Silurian marine faunas in the cover of Oaxaquia, is more consistent with the direct collision of Gondwana and Laurentia at the end of the Ordovician, forming the Acatlan Complex between.
Gérard M. Stampfli - One of the best experts on this subject based on the ideXlab platform.
-
pre mesozoic alpine basements their place in the european paleozoic framework
Geological Society of America Bulletin, 2013Co-Authors: Jurgen F Von Raumer, Francois Bussy, Urs Schaltegger, Bernhard Schulz, Gérard M. StampfliAbstract:Prior to their Alpine overprinting, most of the pre-Mesozoic basement areas in Alpine orogenic structures shared a complex evolution, starting with Neoproterozoic sediments that are thought to have received detrital input from both West and East Gondwanan cratonic sources. A subsequent Neoproterozoic–Cambrian active margin setting at the Gondwana margin was followed by a Cambrian–Ordovician rifting period, including an Ordovician cordillera-like active margin setting. During the Late Ordovician and Silurian periods, the future Alpine domains recorded crustal extension along the Gondwana margin, announcing the future opening of the Paleotethys oceanic domain. Most areas then underwent Variscan orogenic events, including continental subduction and collisions with Avalonian-type basement areas along Laurussia and the juxtaposition and the duplication of terrane assemblages during strike slip, accompanied by contemporaneous crustal shortening and the subduction of Paleotethys under Laurussia. Thereafter, the final Pangea assemblage underwent Triassic and Jurassic extension, followed by Tertiary shortening, and leading to the buildup of the Alpine mountain chain. Recent plate-tectonic reconstructions place the Alpine domains in their supposed initial Cambrian–Ordovician positions in the eastern part of the Gondwana margin, where a stronger interference with the Chinese blocks is proposed, at least from the Ordovician onward. For the Visean time of the Variscan continental collision, the distinction of the former tectonic lower-plate situation is traceable but becomes blurred through the subsequent oblique subduction of Paleotethys under Laurussia accompanied by large-scale strike slip. Since the Pennsylvanian, this global collisional scenario has been replaced by subsequent and ongoing shortening and strike slip under rising geothermal conditions, and all of this occurred before all these puzzle elements underwent the complex Alpine reorganization.
-
The birth of the Rheic Ocean - Early Palaeozoic subsidence patterns and subsequent tectonic plate scenarios
Tectonophysics, 2008Co-Authors: Jürgen F. Von Raumer, Gérard M. StampfliAbstract:New plate-tectonic reconstructions of the Gondwana margin suggest that the location of Gondwana-derived terranes should not only be guided by the models, but should also consider the possible detrital input from some Asian blocks (Hunia), supposed to have been located along the Cambrian Gondwana margin, and accreted in the Silurian to the North-Chinese block. Consequently, the Gondwana margin has to be subdivided into a more western domain, where the future Avalonian blocks will be separated from Gondwana by the opening Rheic Ocean, whereas in its eastern continuation, hosting the future basement areas of Central Europe, different periods of crustal extension should be distinguished. Instead of applying a rather cylindrical model, it is supposed that crustal extension follows a much more complex pattern, where local back-arcs or intra-continental rifts are involved. Guided by the age data of magmatic rocks and the pattern of subsidence curves, the following extensional events can be distinguished:-During the early to middle Cambrian, a back-arc setting guided the evolution at the Gondwana margin. Contemporaneous intra-continental rift basins developed at other places related to a general post-Pan-African extensional phase affecting Africa-Upper Cambrian formation of oceanic crust is manifested in the Chamrousse area, and may have lateral cryptic relics preserved in other places. This is regarded as the oceanisation of some marginal basins in a context of back-arc rifting. These basins were closed in a mid-Ordovician tectonic phase, related to the subduction of buoyant material (mid-ocean ridge?)-Since the Early Ordovician, a new phase of extension is observed, accompanied by a large-scale volcanic activity, erosion of the rift shoulders generated detritus (Armorican Quartzite) and the rift basins collected detrital zircons from a wide hinterland. This phase heralded the opening of Palaeotethys, but it failed due to the Silurian collision (Eo-Variscan phase) of an intra-oceanic arc with the Gondwana margin. During this time period, at the eastern wing of the Gondwana margin begins the drift of the future Hunia microcontinents, through the opening of an eastern prolongation of the already existing Rheic Ocean. The passive margin of the remaining Gondwana was composed of the Galatian superterranes, constituents of the future Variscan basement areas. Remaining under the influence of crustal extension, they will start their drift to Laurussia since the earliest Devonian during the opening of the Palaeotethys Ocean. © 2008 Elsevier B.V. All rights reserved.
-
Gondwana derived microcontinents the constituents of the variscan and alpine collisional orogens
Tectonophysics, 2003Co-Authors: Jurgen F Von Raumer, Gérard M. Stampfli, Francois BussyAbstract:Abstract The European Variscan and Alpine mountain chains are collisional orogens, and are built up of pre-Variscan “building blocks” which, in most cases, originated at the Gondwana margin. Such pre-Variscan elements were part of a pre-Ordovician archipelago-like continental ribbon in the former eastern prolongation of Avalonia, and their present-day distribution resulted from juxtaposition through Variscan and/or Alpine tectonic evolution. The well-known nomenclatures applied to these mountain chains are the mirror of Variscan resp. Alpine organization. It is the aim of this paper to present a terminology taking into account their pre-Variscan evolution at the Gondwana margin. They may contain relics of volcanic islands with pieces of Cadomian crust, relics of volcanic arc settings, and accretionary wedges, which were separated from Gondwana by initial stages of Rheic ocean opening. After a short-lived Ordovician orogenic event and amalgamation of these elements at the Gondwanan margin, the still continuing Gondwana-directed subduction triggered the formation of Ordovician Al-rich granitoids and the latest Ordovician opening of Palaeo-Tethys. An example from the Alps (External Massifs) illustrates the gradual reworking of Gondwana-derived, pre-Variscan elements during the Variscan and Alpine/Tertiary orogenic cycles.
-
Gondwana-derived microcontinents — the constituents of the Variscan and Alpine collisional orogens
Tectonophysics, 2003Co-Authors: Jurgen F Von Raumer, Gérard M. Stampfli, Francois BussyAbstract:Abstract The European Variscan and Alpine mountain chains are collisional orogens, and are built up of pre-Variscan “building blocks” which, in most cases, originated at the Gondwana margin. Such pre-Variscan elements were part of a pre-Ordovician archipelago-like continental ribbon in the former eastern prolongation of Avalonia, and their present-day distribution resulted from juxtaposition through Variscan and/or Alpine tectonic evolution. The well-known nomenclatures applied to these mountain chains are the mirror of Variscan resp. Alpine organization. It is the aim of this paper to present a terminology taking into account their pre-Variscan evolution at the Gondwana margin. They may contain relics of volcanic islands with pieces of Cadomian crust, relics of volcanic arc settings, and accretionary wedges, which were separated from Gondwana by initial stages of Rheic ocean opening. After a short-lived Ordovician orogenic event and amalgamation of these elements at the Gondwanan margin, the still continuing Gondwana-directed subduction triggered the formation of Ordovician Al-rich granitoids and the latest Ordovician opening of Palaeo-Tethys. An example from the Alps (External Massifs) illustrates the gradual reworking of Gondwana-derived, pre-Variscan elements during the Variscan and Alpine/Tertiary orogenic cycles.