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| Lochkovian | |
|---|---|
| Name | Lochkovian |
| Color | #a6cee3 |
| Time start | 419.2 |
| Time end | 410.8 |
| Unit | Epoch/Stage |
| Era | Paleozoic (Early Devonian) |
| Named by | A. Barrande |
| Named for | Lochkov (Prague) |
| Type section | Prague Basin |
Lochkovian
The Lochkovian is the lowest stage of the Devonian Period and marks a major boundary within the Paleozoic between the Silurian and Devonian. It underpins chronostratigraphic frameworks used by projects at the International Commission on Stratigraphy, informs regional schemes such as the Old Red Sandstone frameworks of Scotland and Ireland, and anchors biostratigraphic correlations involving faunas from the Rhineland, Bohemia, Holy Cross Mountains, and Moscow Basin. The stage is integral to studies by institutions like the Natural History Museum, London, the Smithsonian Institution, the Paleontological Society, and the British Geological Survey.
The Lochkovian is formally defined by a Global Boundary Stratotype Section and Point (GSSP) near Prague in the Czech Republic and is temporally placed at the base of the Devonian Epoch following the Pridoli Series of the Silurian and preceding the Pragian Stage. Key organizations and figures that ratified its limits include the International Commission on Stratigraphy, commissions within the International Union of Geological Sciences, and stratigraphers such as A. Barrande and modern committees comprising members from the Geological Society of America, the European Geosciences Union, and the Russian Academy of Sciences. The Lochkovian spans approximately 419.2 to 410.8 million years ago according to timescales produced by the Geologic Time Scale 2012 and updates by the International Chronostratigraphic Chart.
Lithostratigraphic units that record the Lochkovian include formations in the Prague Basin, the Old Red Sandstone facies of Scotland, the Visean-overlying sequences in England, and carbonate successions in the Rheinisches Schiefergebirge and Holy Cross Mountains. Typical lithologies comprise siliciclastic sandstones linked to the Old Red Sandstone continent, shallow marine limestones comparable to units exposed in Belgium and Germany, and mixed hemipelagic shales as seen in sections of the Moscow Basin and Baltic provinces. Stratigraphic schemes used by the British Geological Survey, Geological Survey of Canada, and Polish Geological Institute often subdivide Lochkovian deposits using conodont and ammonoid biozones employed by workers from Yale University, the University of Cambridge, and the University of Warsaw.
Fossil assemblages in Lochkovian strata are notable for early placoderm fishes, primitive osteichthyan remains, and diverse invertebrate faunas including brachiopods, trilobites, conodonts, and early ammonoids. Key taxa documented by researchers at the Natural History Museum, London, Smithsonian Institution, and the Ludwig Maximilian University of Munich include genera comparable to descriptions by Ernest Koken, Roderick Murchison, and later paleontologists at the University of Bonn. Conodont zonation developed by teams from the University of Geneva and the Russian Academy of Sciences provides precise biochronology, while vertebrate discoveries attributed to collaborators from the Institute of Paleobiology, Polish Academy of Sciences and the University of Chicago have informed phylogenies treated in works from the Paleontological Society and monographs published by the Cambridge University Press.
Lochkovian depositional settings range from continental fluvial and lacustrine basins exemplified by the Old Red Sandstone of Scotland and Ireland to epicontinental seas recorded in the Rhenish Massif, Bohemia, and Holy Cross Mountains. Paleogeographic reconstructions by groups at the Smithsonian Institution, the Potsdam Institute for Climate Impact Research, and the University of Lausanne place these deposits on margins of the paleocontinents Laurussia and Gondwana with faunal links to the Armorica terrane and microcontinents studied by teams from the Geological Survey of Spain and the University of Barcelona. Sedimentological analyses supported by the Geological Survey of Finland and the Federal Institute for Geosciences and Natural Resources (BGR) indicate transgressive-regressive cycles tied to regional tectonics documented by researchers at the University of Geneva and the Royal Belgian Institute of Natural Sciences.
The Lochkovian correlates globally with lowermost Devonian series in stratotypes across Europe, North America, and parts of Asia. Correlative units include parts of the Old Red Sandstone in Scotland and Norway, Baltic successions in the Estonian and Latvian basins, and platform carbonates in Morocco and the Anti-Atlas studied by teams from the University of Rabat and the University of Marrakech. International correlation frameworks produced by the International Commission on Stratigraphy, the Paleobiology Database, and regional surveys (e.g., US Geological Survey, Geological Survey of Canada) integrate conodont, brachiopod, and ammonoid biozones recognized by researchers from Utrecht University, University of Oslo, and Moscow State University.
Lochkovian strata host reservoir and source rocks significant to regional resource assessments undertaken by the British Geological Survey, Polish Geological Institute, and the Norwegian Petroleum Directorate. Sandstone units within the Old Red Sandstone facies and carbonate platforms in the Rhenish Massif and Bohemian Massif have been investigated for groundwater resources by the Czech Geological Survey and for mineralization related to vein systems studied by the Federal Institute for Geosciences and Natural Resources (BGR). Quarrying of Lochkovian limestones for construction and industrial uses occurs in localities documented in reports from the European Commission and national geological surveys, while fossiliferous horizons inform museum collections at the Natural History Museum, London, the Smithsonian Institution, and the National Museum in Prague.
Category:Devonian stages