Westphalian (stage)

Last updated
System Series
(NW Europe)		 Stage
(NW Europe)		 Series
(ICS)		 Stage
(ICS)		Age
(Ma)
Permian younger
Carboniferous Silesian Stephanian Pennsylvanian Gzhelian 298.9–303.7
Kasimovian 303.7–307.0
Westphalian Moscovian 307.0–315.2
Bashkirian 315.2–323.2
Namurian
Mississippian Serpukhovian 323.2–330.9
Dinantian Visean Visean 330.9–346.7
Tournaisian Tournaisian 346.7–358.9
Devonian older
Subdivisions of the Carboniferous system in Europe compared with the official ICS-stages (as of 2018)

The Westphalian is a regional stage or age in the regional stratigraphy of northwest Europe, with an age between roughly 315 [1] [2] and 307 [1] [3] Ma (million years ago). It is a subdivision of the Carboniferous System or Period and the regional Silesian Series. The Westphalian is named for the region of Westphalia (German: Westfalen) in western Germany where strata of this age occur. The Coal Measures of England and Wales are also largely of Westphalian age, though they also extend into the succeeding Stephanian.

Contents

The Westphalian is preceded by the Namurian Stage/Age (which corresponds to the Millstone Grit Series of Great Britain) and succeeded by the Stephanian Stage/Age (which corresponds to the uppermost part of the Coal Measures of Great Britain).

In the official geologic time scale of the International Commission on Stratigraphy (ICS [1] ), the Westphalian is placed within the Pennsylvanian Subsystem/Subperiod (323-299 Ma) of the Carboniferous System/Period. As a regionally defined stage, the Westphalian overlaps with official ICS stages which are in use on an international level. The Westphalian extends from the approximately the upper half of the Bashkirian Stage through the Moscovian Stage, [4] and possibly includes a small portion of the Kasimovian Stage. [5] Many older scientific sources refer to the Westphalian as an epoch or series, which are higher geological ranks than its current status.

Stratigraphy

Since 1935, the Westphalian has been split into four substages, from oldest to youngest: Langsettian (Westphalian A), Duckmantian (Westphalian B), Bolsovian (Westphalian C), and "Asturian" (Westphalian D). These substages are defined by guide fossils, or "index fossils," particularly plant macrofossils, miospores, and ammonoids. [6] [7] [4] The Westphalian exhibits distinctive changes in plant diversity, and many plant macrofossil assemblage zones have been defined across an area encompassing Europe, Turkey, and the Maritime Provinces of Canada. [8]

Langsettian

The Langsettian, previously known as Westphalian A, is named after the village of Langsett in South Yorkshire, England. It marks the base of the Westphalian regional stage, as defined by the ammonoid Gastrioceras subcrenatum . [6] The base of the Langsettian (and the Westphalian as a whole) has been dated to around 319.9 [9] or 319.2 [2] Ma.

The Langsettian corresponds to the Calymmotheca ("Lyginopteris") hoeninghausii assemblage zone. [8] Many widespread plant species first appear near the base of the Langsettian, indicating a spike of diversification in tropical coal swamp habitats. [8] [10] Plant diversity steadily increases through the entire Langsettian, though this may be a result of ecological factors such as the receding coastline. [8]

Duckmantian

The Duckmantian, previously known as Westphalian B, is named after the village of Duckmanton in Derbyshire, England. The base of the Duckmantian is defined by the ammonoid Anthracoceratites vaderbeckei . [6] The boundary between the global Bashkirian and Moscovian stages (~315.2 Ma) [4] corresponds to the mid-late part of the Duckmantian. [9] [4]

The lower-middle part of the Duckmantian corresponds to the Lonchopteris rugosa Assemblage-zone, the most diverse plant biozone in the Carboniferous coalfields of Europe. The rising diversity trend of the Langsettian continues into this biozone, with few notable changes in species composition. In the majority of European coalfields, plant diversity reached a plateau around halfway through the Duckmantian. Coal swamps became increasingly unstable in the Paripteris linguaefolia assemblage zone, which begins in the upper part of the Duckmantian. [8] [10]

Bolsovian

The Bolsovian, previously known as Westphalian C, is named after the town of Bolsover in Derbyshire. The base of the Bolsovian is defined by the ammonoid Donetzoceras aegiranum , [6] and has an estimated age of around 313.8 [9] or 313.7 [5] Ma.

The Paripteris linguaefolia assemblage zone continues into the Bolsovian, and a decline in plant diversity is apparent across the entirety of Europe. [8] In a few coalfields, such as the Nord-Pas-des-Calais basin of northern France, the decline is delayed until the mid-Bolsovian, while in other areas it may begin as early as the late Duckmantian. The overall downward diversity trend is slight, but several notable lycopsid and sphenopsid species disappear from European coal swamps at this time. [10]

Westphalian D

Westphalian D is often referred to as the Asturian, named after the Asturias region of northwest Spain. [11] In most of Europe, Westphalian D is distinguished by plant fossils. Asturias is one of the few European regions with enough late Westphalian marine fossils to allow for precise correlations with other marine strata. The proposal to fully implement the name "Asturian" has yet to be ratified, as some stratigraphic difficulties in Spain are not fully resolved. [4] [3]

The lower part of the Asturian belongs to the Linopteris obliqua assemblage zone [8] (sometimes termed the Linopteris bunburii zone). [5] This biozone is notably lower in diversity than previous Westphalian biozones. Plant fossils are still common over much of Europe, with Neuropteris ovata as a particularly abundant species. [8] An important ecological turnover occurs about halfway through the Asturian (~309 Ma), [5] with the arrival of the Crenulopteris acadica assemblage zone [12] [5] [8] [10] (previously known as the Lobatopteris vestita zone). [7] Lycopsid fossils become very rare, while marattialean ferns become abundant in coal swamp deposits. [8] Many European coalfields were positioned in a foreland basin north of the Variscan orogeny. As mountain-building continued, uplift accelerated in the basin, endangering the survival of coal swamp environments. [8] [10]

Plant fossils (and coal deposits as a whole) are uncommon in the following "Cantabrian" substage of the Stephanian Stage. [3] The end of the Asturian is a topic of strong debate; most estimates place the Westphalian-Stephanian boundary before the start of the Kasimovian global stage (~307 Ma), [6] [4] [3] whereas a few place the boundary within the Kasimovian. [5] U-Pb radiometric dating of tonstein beds in Spain estimate that the Asturian lasted from 310.7 to 307.5 Ma, ending just prior to the Kasimovian. [3]

Life

The Westphalian interval is widely recognized for its coal deposits-- rocks that were deposited broadly across regions that were in low paleolatitudes. These deposits, from so-called "coal swamps" have yielded rich assemblages of fossils including spore-bearing and seed-bearing plants, fishes, and tetrapods. [13] [14] [15] Amphibians were diverse and dominated some communities. The collapse of the rainforest ecology between the Moscovian and Kasimovian removed many amphibian species that did not survive as well in the cooler, drier conditions. Reptiles, however prospered due to specific key adaptations and underwent a major evolutionary radiation, in response to the drier climate that led to the rainforest collapse. [16] [17]

Related Research Articles

<span class="mw-page-title-main">Carboniferous</span> Fifth period of the Paleozoic Era, 359–299 million years ago

The Carboniferous is a geologic period and system of the Paleozoic that spans 60 million years from the end of the Devonian Period 358.9 Ma to the beginning of the Permian Period, 298.9 Ma. In North America, the Carboniferous is often treated as two separate geological periods, the earlier Mississippian and the later Pennsylvanian.

The Pennsylvanian is, on the ICS geologic timescale, the younger of two subperiods of the Carboniferous Period. It lasted from roughly 323.2 million years ago to 298.9 million years ago. As with most other geochronologic units, the rock beds that define the Pennsylvanian are well identified, but the exact date of the start and end are uncertain by a few hundred thousand years. The Pennsylvanian is named after the U.S. state of Pennsylvania, where the coal-producing beds of this age are widespread.

In the geologic timescale, the Asselian is the earliest geochronologic age or lowermost chronostratigraphic stage of the Permian. It is a subdivision of the Cisuralian Epoch or Series. The Asselian lasted between 298.9 and 293.52 million years ago (Ma). It was preceded by the Gzhelian and followed by the Sakmarian.

The Bashkirian is in the International Commission on Stratigraphy geologic timescale the lowest stage or oldest age of the Pennsylvanian. The Bashkirian age lasted from 323.2 to 315.2 Ma, is preceded by the Serpukhovian and is followed by the Moscovian.

<span class="mw-page-title-main">Tournaisian</span> First stage of the Carboniferous

The Tournaisian is in the ICS geologic timescale the lowest stage or oldest age of the Mississippian, the oldest subsystem of the Carboniferous. The Tournaisian age lasted from 358.9 Ma to 346.7 Ma. It is preceded by the Famennian and is followed by the Viséan. In global stratigraphy, the Tournaisian contains two substages: the Hastarian and Ivorian. These two substages were originally designated as European regional stages.

<span class="mw-page-title-main">Serpukhovian</span> Third stage of the Carboniferous

The Serpukhovian is in the ICS geologic timescale the uppermost stage or youngest age of the Mississippian, the lower subsystem of the Carboniferous. The Serpukhovian age lasted from 330.9 Ma to 323.2 Ma. It is preceded by the Visean and is followed by the Bashkirian. The Serpukhovian correlates with the lower part of the Namurian Stage of European stratigraphy and the middle and upper parts of the Chesterian Stage of North American stratigraphy.

The Kasimovian is a geochronologic age or chronostratigraphic stage in the ICS geologic timescale. It is the third stage in the Pennsylvanian, lasting from 307 to 303.7 Ma. The Kasimovian Stage follows the Moscovian and is followed by the Gzhelian. The Kasimovian saw an extinction event which occurred around 305 mya, referred to as the Carboniferous Rainforest Collapse. It roughly corresponds to the Missourian in North American geochronology and the Stephanian in western European geochronology.

<span class="mw-page-title-main">Gzhelian</span> Seventh and final stage of the Carboniferous

The Gzhelian is an age in the ICS geologic timescale or a stage in the stratigraphic column. It is the youngest stage of the Pennsylvanian, the youngest subsystem of the Carboniferous. The Gzhelian lasted from 303.7 to 298.9 Ma. It follows the Kasimovian age/stage and is followed by the Asselian age/stage, the oldest subdivision of the Permian system.

<i>Cochleosaurus</i> Extinct genus of temnospondyls

Cochleosaurus (“spoon lizard”, from the Latin cochlear "spoon" and Greek sauros “lizard”_ were medium-sized edopoid temnospondyls that lived in Euramerica during the Muscovian period. Two species, C. bohemicus and C. florensis, have been identified from the fossil record.

<i>Euproops</i> Genus of horseshoe crab relatives

Euproops is an extinct genus of xiphosuran, related to the modern horseshoe crab. It lived during the Carboniferous Period.

<span class="mw-page-title-main">Allegheny Group</span> Pennsylvanian-age geological unit

The Allegheny Group, often termed the Allegheny Formation, is a Pennsylvanian-age geological unit in the Appalachian Plateau. It is a major coal-bearing unit in the eastern United States, extending through western and central Pennsylvania, western Maryland and West Virginia, and southeastern Ohio. Fossils of fishes such as Bandringa are known from the Kittaning Formation, which is part of the Allegheny Group.

The Moscovian is in the ICS geologic timescale a stage or age in the Pennsylvanian, the youngest subsystem of the Carboniferous. The Moscovian age lasted from 315.2 to 307 Ma, is preceded by the Bashkirian and is followed by the Kasimovian. The Moscovian overlaps with the European regional Westphalian stage and the North American Atokan and Desmoinesian stages.

The Namurian is a stage in the regional stratigraphy of northwest Europe, with an age between roughly 331 and 319 Ma. It is a subdivision of the Carboniferous system or period, as well as the regional Silesian series. The Namurian is named for the Belgian city and province of Namur where strata of this age occur. The Millstone Grit Group in the lithostratigraphy of northern England and parts of Wales is also of Namurian age.

The Stephanian is a stage in the regional stratigraphy of northwest Europe with an age between roughly 307.5 and 299 Ma. It is a subdivision of the Carboniferous system or period and the regional Silesian series. The uppermost units of the Coal Measures of England and Wales are probably of Stephanian age, though the larger part of this formation is referred to the earlier Westphalian. The stage derives its name from the city of Saint-Étienne for its coal mining basin in eastern central France where strata of this age occur.

<span class="mw-page-title-main">Callistophytaceae</span> Extinct family of seed ferns

The Callistophytaceae was a family of seed ferns (pteridosperms) from the Carboniferous and Permian periods. They first appeared in late Middle Pennsylvanian (Moscovian) times, 306.5–311.7 million years ago (Ma) in the tropical coal forests of Euramerica, and became an important component of Late Pennsylvanian vegetation of clastic soils and some peat soils. The best known callistophyte was documented from Late Pennsylvanian coal ball petrifactions in North America.

<span class="mw-page-title-main">Carboniferous rainforest collapse</span> Extinction event at the end of the Moscovian in the Carboniferous

The Carboniferous rainforest collapse (CRC) was a minor extinction event that occurred around 305 million years ago in the Carboniferous period. The event occurred at the end of the Moscovian and continued into the early Kasimovian stages of the Pennsylvanian.

<span class="mw-page-title-main">Coal measures</span>

In lithostratigraphy, coal measures are coal-bearing strata, with the term typically applied to European units of the Upper Carboniferous System.

The South Wales Coal Measures Group is a lithostratigraphical term referring to the coal-bearing succession of rock strata which occur in South Wales within the Westphalian Stage of the Carboniferous Period. The Group name is also applied to rocks of similar age across southern England from the Bristol Coalfield east to the concealed Oxfordshire, Berkshire and Kent Coalfields. In formal use, the term replaces the earlier Coal Measures Group The Group comprises the:

<i>Macroneuropteris</i> Extinct genus of plants

Macroneuropteris is a genus of Carboniferous seed plants in the order Medullosales. The genus is best known for the species Macroneuropteris scheuchzeri, a medium-size tree that was common throughout the late Carboniferous Euramerica. Three similar species, M. macrophylla, M. britannica and M. subauriculata are also included in the genus.

The Scottish Coal Measures Group is a lithostratigraphic unit referring to the coal-bearing succession of rock strata which occur in Scotland during the Westphalian regional stage of the Carboniferous Period. It is the Scottish portion of the informal Coal Measures Group, which also includes the South Wales and Pennine coal measures. The Scottish coal measures are well-exposed across the Midland Valley. The group is also found within small grabens in the vicinity of Sanquhar and Thornhill.

References

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  3. 1 2 3 4 5 Knight, John A.; Cleal, Christopher J.; Álvarez-Vázquez, Carmen (2023-06-14). "The challenge of relating the Kasimovian to west European chronostratigraphy: a critical review of the Cantabrian and Barruelian substages of the Stephanian Stage". Geological Society, London, Special Publications. 535 (1): 31–71. Bibcode:2023GSLSP.535..189K. doi: 10.1144/SP535-2022-189 . ISSN   0305-8719.
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  8. 1 2 3 4 5 6 7 8 9 10 11 Opluštil, Stanislav; Cleal, Christopher J.; Wang, Jun; Wan, Mingli (2022). "Carboniferous macrofloral biostratigraphy: an overview". Geological Society, London, Special Publications. 512 (1): 813–863. Bibcode:2022GSLSP.512..813O. doi:10.1144/SP512-2020-97. ISSN   0305-8719.
  9. 1 2 3 Pointon, Michael A.; Chew, David M.; Ovtcharova, Maria; Sevastopulo, George D.; Crowley, Quentin G. (2012). "New high-precision U–Pb dates from western European Carboniferous tuffs; implications for time scale calibration, the periodicity of late Carboniferous cycles and stratigraphical correlation". Journal of the Geological Society. 169 (6): 713–721. Bibcode:2012JGSoc.169..713P. doi:10.1144/jgs2011-092. hdl: 2262/79149 . ISSN   0016-7649.
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  11. ↑ Wagner, R.H.; Sánchez de Posada, L.C.; Martínez Chacón, M.L.; Fernández, L.P.; Villa, E.; Winkler Prins, C.F. (2002). "The Asturian Stage: a preliminary proposal for the definition of a substitute for Westphalian D". Canadian Society of Petroleum Geologists, Memoir. 19: 832–850.
  12. ↑ Wittry, Jack; Glasspool, Ian J.; Béthoux, Olivier; Koll, Rebecca; Cleal, Christopher J. (2015-08-03). "A revision of the Pennsylvanian marattialean fern Lobatopteris vestita auct . and related species". Journal of Systematic Palaeontology. 13 (8): 615–643. Bibcode:2015JSPal..13..615W. doi:10.1080/14772019.2014.936915. ISSN   1477-2019.
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  14. ↑ Hook, R. W.; Baird, D. (1986). "The Diamond Coal Mine of Linton, Ohio, and its Pennsylvanian-age vertebrates". Journal of Vertebrate Paleontology. 6 (2): 174–190. Bibcode:1986JVPal...6..174H. doi:10.1080/02724634.1986.10011609.
  15. ↑ Babcock, L. E. (2024). "Replacement names for two species of Orthacanthus Agassiz, 1843 (Chondrichthyes, Xenacanthiformes), and discussion of Giebelodus Whitley, 1940, replacement name for Chilodus Giebel, 1848 (Chondrichthyes, Xenacanthiformes), preoccupied by Chilodus Müller & Troschel, 1844 (Actinopterygii, Characiformes)". ZooKeys (1188): 219–226. doi: 10.3897/zookeys.1188.108571 .
  16. ↑ Sahney, S., Benton, M.J. & Falcon-Lang, H.J. (2010). "Rainforest collapse triggered Pennsylvanian tetrapod diversification in Euramerica" (PDF). Geology. 38 (12): 1079–1082. doi:10.1130/G31182.1.{{cite journal}}: CS1 maint: multiple names: authors list (link)
  17. ↑ M. Alan Kazlev (1998) The Carboniferous Period of the Paleozoic Era: 299 to 359 million years ago, Palaeos.org, Retrieved on 2008-06-23
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