Bull. Soc. belge Géologie T. 83 fasc. 4 pp. 235- 253 Bruxelles 1974

THE CHRONOSTRATIGRAPHIC UNITS OF THE UPPER CARBONIFEROUS IN EUROPE

R.H. WAGNER *

ABSTRACT: The history is traced of the various chronostratigraphic units recognised in the Upper Carboniferous of western Europe, and their stratotypes are discussed. A correlation is given for the chronostratigraphic units in the Middle and Upper Carboniferou& series of Russia, in the light of pre­ dominantly marine successions in N.W. Spain, and suggestions are made for an integrated scheme of major units.

Introduction In western Europe the classification of Carboniferous strata was further taken in The main chronostratigraphic divisions of hand by the Congrès pour !'Avancement des the Carboniferous in Europe were established Etudes de Stratigraphie Carbonifère which by MUNIER CHALMAS & DE LAPPARENT(1893), met in Heerlen in 1927, 1935, 1951 and who distinguished three marine stages charac­ 1958. The 1927 congress sanctioned the use terised by different faunas, viz. Dinantienl, of Namurian, a stage introduced by PURVES Moscovien2 and Ouralienl, and two stages, in 1883 and which corresponds to the West­ Westphalien1 and Stéphanien, characterised phalien inférieur of MUNIER CHALMAS & by coal-measures facies. Most of the names DE LAPPARENT. It also introduced the A, had been used before (see footnotes), but B and C divisions for the remaining West­ the 'Note sur la Nomenclature des Terrains phalian (i.e. the Westphalien supérieur of sédimentaires' provided the first formai MUNIER CHALMAS & DE LAPPARENT). The framework for a subdivision into stages of the 1935 congress expanded the Westphalian Carboniferous System. MuNIER CHALMAS & upwards by recognising the presence of a DE LAPPARENT gave precedence to the marine Westphalian D division, and subdivided the stages, Moscovian and Uralian, and regarded Namurian into A, B and C. A subdivision Westphalian and Stephanian as the equivalent of the Stephanian Stage into Stephanian A, units in non-marine facies. This marked a B and C appeared in PRUVOST 1934, and was duality which was to remain in all subsequent proposed in JoNGMANS & PRUVOST (1950). classifications3. This usage was followed by different authors and became finally incorporated in the (*) Department of Geology, The University, stratigraphie scheme published in the Compte Mappin Street, Sheffield Sl 3JD, England. rendu of the 7th Carboniferous Congress Paper presented in Brussels in November 1973. which was held in Krefeld (1971). 1 ( ) First named by DE LAPPARENT & MUNJER It should be noted that the stratigraphie CHALMAS in DE LAPPARENT (1892) 'Traité de scheme elaborated by the Heerlen congresses Géologie'. Ouralien replaced Gshelien which was based entirely on the knowledge gained in had been introduced by NIKITIN (1890). The latter name has been maintained in the present-day Russian classification. & HAVLENA (1962), who introduced the term ( 2) Name introduced by NIKITIN (1890). Sorabian for the non-marine equivalent of ( 3) lt was taken to its logical extreme by REMY the Dinantian.

235 north-western Europe, showing paralic and Carboniferous System has been adopted non-marine developments of the Upper (GEORGE & WAGNER 1972, p. 142) (Table 1). Carboniferous. Little or no notice was taken of the marine Carboniferous in Russia, where a separate classification became established. Major subdivisions Although papers on the predominantly marine Carboniferous in Russia did appear in the The main feature of this classification is the Compte-rendus of successive congresses, there recognition of two subsystems, the Dinantian was no serious attempt at incorporating this (or Lower Carboniferous) and the Silesian information for an integrated European sche­ (or Upper Carboniferous). The name Silesian me of Carboniferous stratigraphie classifica­ was introduced in Heerlen (1958) and the tion. Similarly, comparisons were made with decision to recognise a Silesian division the United States, but without making an equal in rank to the Dinantian was ratified attempt at an integrated scheme. in Copenhagen, 1960 (VAN LECKWIJCK With the establishment of the Commission 1964a). These main divisions of the Car­ on Stratigraphy of the International Geologi­ boniferousinEurope are comparable although cal Congress at Algiers, 1952, it was also not wholly correlatable to Mississippian decided to constitute a Subcommission on and Pennsylvanian, two systems of the Ameri­ Carboniferous Stratigraphy which would work can Palaeozoic which, together, equal the alongside the other subcommissions dealing Carboniferous System of Europe. At the with the other systems, and with the Sub­ meeting in Heerlen, 1958, it was recommended commission on Stratigraphie Classification that these major subdivisions of the Car­ (originally called the Subcommission on boniferous System should not be regarded as Stratigraphie Nomenclature). The Subcom­ subsystems, but this recommendation was mission on Carboniferous Stratigraphy, under deleted at Copenhagen. It therefore became its Chairman, Prof. W.P. VAN LECKWIJCK, inferred that Dinantian and Silesian, as well presented its first two reports in the Compte as Mississippian and Pennsylvanian should rendu of the Carboniferous Congress of 1958 be regarded as subsystems, since the congress and in the Proceedings of the International re-affirmed that the Carboniferous should be Geological Congress held at Copenhagen in maintained as a single system. 1960. This Subcommission was subsequently The rank of the Dinantian and Silesian made accountable to the International Union divisions as subsystems was further confirmed of Geological Sciences. Its meetings were indirectly when the subordinate units Tour­ not necessarily coïncident with those of the naisian, Viséan, Namurian, Westphalian and International Congress on Carboniferous Stephanian were admitted as series. The first Stratigraphy and Geology, and the initiative unit to be regarded as such was the Namurian for making recommendations on the classifi­ which accommodated a number of stages as cation of Carboniferous stratigraphie units introduced by BISAT (1924), HUDSON & COT­ passed from the Congress to the Subcommis­ TON (1943), HUDSON (1945) and HODSON sion. However, in practice, the latter took (1957) (see 'Interim Report of the Namurian care to hold its general meetings in conjunc­ Working Group' by W.H.C. RAMSBOTTOM tion with the Carboniferous Congress and its 1969). Once the Namurian had been recogni­ reports were read during the closing sessions sed as a series (VAN LECKWIJCK 1964b), of the congress at Paris (1963), Sheffield it became inevitable that the Westphalian (1967) and Krefeld (1971). Additional meetings and Stephanian should also be regarded as of the Subcommission were held in Copenha­ series. Their major subdivisions (stages), gen (1960), Sheffield (1965), Liège (1969), carrying the informai connotations A, B, C Spain (1970) and Czechoslovakia (1973). and D, are in due time to be renamed in the Reports were issued for ail these meetings. more formai manner, just Iike the stages At present, the following classification of the within the Namurian Series. One newly

236 TABLE 1 Chronostratigraphic units of the European Carboniferous.

SYSTEM SUBSYSTEM SERIES STAGE

{ Stophacian C Stephanian B Stephanian f Stephanian A 1 Cantabrian

1 IWestphalian D Westphalian C SILESIAN ~ Westphalian l Westphalian B 1 Westphalian A 1 1 1 Yeadonian 1 Marsdenian CARBONIFEROUS 1 Kinderscoutian l Namurian Alportian Chokierian Arnsbergian Pendleian ...... DINANTIAN { Viséan Tournaisian ......

described stage, the Cantabrian, the basal (and which has been accepted as a stratotype unit of the Stephanian Series, constitutes a by the Subcommission on Carboniferous precedent for the formai naming of stages now Stratigraphy in Sheffield 1967) does not coïn• marked A, B and C. cide with the Heerlen definition. This has Since the Dinantian was regarded as created obvious difficulties which have not equivalent in rank to the Silesian, it also been removed by recent proposais to recognise became inevitable to recognise the Tournai­ stages with German stratotypes for the zones sian and the Viséan as series. However, no I, II and III (PAPROTH et al. 1971, SCHMIDT stages were recognised within these series. 1972). One reason for the failure to designate general­ The level of subdivision within the Dinan­ ly agreed stages for the Tournaisian and tian is obviously not as high as that reached Viséan series may be that these units were within the Silesian, and the question may well subdivided into the goniatite zones I (Gatten­ be asked whether these two units should dorfia Stufe), II (Pericyclus Stufe) and III really be regarded as being of the same rank. (Goniatites Stufe), as proposed by ScHINDE­ In this respect, it may be significant that WOLF & PAECKELMANN and accepted by the MUNIER CHALMAS & DE LAPPARENT (1893) second Heerlen congress (JoNGMANS & intended the Dinantian to be equivalent in GoTHAN 1937). On the basis of the decisions rank to the Westphalian and the Stephanian. taken at that congress, the Tournaisian/ Also in terms of absolute time, it appears that Viséan boundary would lie within zone II. the Dinantian unit is more nearly equivalent On the other hand, the boundary between to any of the component series of the Silesian these two units as recognised in Belgium than to the latter unit in its entirety. FRANCIS &

237 TABLE 2 Correlation of major chronostratigraphic units in the Carboniferous of Western Europe and Russia.

WEST EUROPEAN UNITS RUSSIAN UNITS

Subsystem Seri es Seri es Stage

Stephanian Upper Carboniferous lOrenbmg1'rn Gzhelian Silesian J Moscovian Westphalian Middle Carboniferous l Bashkirian 1 Namurian 'N="ria"' (') Viséan Lower Carboniferous lViséan Dinantian Tournaisian Tournaisian

WoonLAND (1964) attributed some 20 million sion made by MUNIER CHALMAS & DE years to the Dinantian, 10-15 m.y. to the LAPPARENT, but there are differences in Namurian, 20 m.y. to the Westphalian, and composition. The Russian Lower Carboni­ 10-15 m.y. to the Stephanian. Although these ferous includes a Namurian Stage which is figures are only rough approximations based equivalent to the lower and middle Namurian on limited data of varying reliability, they do of western Europe. The next stage in the support the general impression that the Russian classification is the Bashkirian Dinantian occupies a good deal less time than which forms part of the Middle Carboni­ the Silesian. ferous, and which is mainly equivalent to the If the Carboniferous is to be maintained upper Namurian of western Europe. It also as a single system (as the Heerlen congress of reaches some way into the lower Westphalian. 1958 has re-affirmed), then it may be recom­ Most of the Russian Middle Carboniferous mended to abolish the subsystems and to is taken up by the Moscovian which is subdivide into the following series: Dinant­ broadly equivalent to the Westphalian. The ian, Namurian, Westphalian, Stephanian. Gzhelian and Orenburgian stages of the Apart from the fact that these are units of Upper Carboniferous are together almost more or less equivalent time value which exactly equivalent to the Stephanian (Table 2). can be readily subdivided into stages (Tour­ It would appear that the West European and naisian and Viséan would then corne into Russian schemes might be brought into line line with Pendleian, Arnsbergian, etc.), quite readily by returning to the threefold it might also facilitate the eventual integration division recommended by MUNIER CHALMAS & of West European chronostratigraphic units (4) The Subcommission on Carboniferous Strati- with those recognised in the U.S.S.R. where graphy has formulated a demand for the the Carboniferous System is subdivided into renaming of the Russian 'Namurian' since the the Lower, Middle and Upper Carboniferous latter is only partly equivalent to the Namurian series. These series reftect the threefold divi- of western Europe (VAN LECKWIJCK 1964a).

238 DE LAPPARENT. On the West European side of these as a type area. There appears to have this would require the abandonment of the been a general feeling that the goniatite traditional Upper Carboniferous or Silesian. zones were world-wide and sufficient in Alternatively, the term Silesian might be themselves to effect widespread correlation. used for the Namurian and Westphalian together (thus returning to the Westphalian Westphalian A, B, C. -sensu lato- of MUNIER CHALMAS & DE The usefulness of the goniatite faunas being LAPPARENT). This would allow the introduc­ generally admitted, there was a conscious tion of three main divisions, viz. the Lower attempt to extend the goniatite zonation Carboniferous (or Dinantian), the Middle upwards into the Westphalian. Indeed, the Carboniferous (or Silesian), and the Upper base of the Westphalian was taken at the Carboniferous (or Stephanian). The threefold Sarnsbank Marine Band with Gastrioceras division in Russia could be maintained, but subcrenatum, the latter being regarded as the it would be necessary to transfer the Russian index goniatite. This decision taken at Heerlen 'Namurian' to the Middle Carboniferous. i!l 1927, was modified in 1935 by eliminating Alternatively, the Namurian of western Europe the reference to the marine band since it was might be split into two parts, the lower part felt that the occurrence of Gastrioceras sub­ to be attached to the Lower Carboniferous and crenatum would furnish an international the upper part to the Middle Carboniferous. marker which should not be linked to any particular locality. In practice, however, the History of the stages of the Upper Carbonife­ occasional marine bands in the Westphalian rous (Silesian) in Western Europe strata of north-western Europe are used as index horizons marking widespread trans­ Namurian gressions on the continental shelf. The faunas The Upper Carboniferous stages recognised occurring in these horizons have only limited by the first Heerlen congress (1927), viz. zonal value, the transgressions being too Namurian, Westphalian and Stephanian, were sporadic for the stratigraphie ranges of the subdivided into units marked A, B, C and D faunal elements to be established. There are by successive congresses. It is interesting to also depth controls on the distribution of follow the thinking behind the various steps these elements, and these impose a restriction taken to effect the subdivision. The first on the faunal composition. Heerlen congress accepted the notion, current Within the peculiar conditions of the paralic at the time, that a stage could be subdivided coal-measures of north-western Europe, which into zones (biozones). Since the goniatite are generally non-marine with only sporadic faunas provided the best means for the cprre­ marine transgressions of an apparently lation of marine and partly marine strata, the eustatic nature (TRUEMAN 1946), the marine Namurian was subdivided into a number of bands furnish undoubtedly the most reliable goniatite zones. W.S. BISAT's work in England means of correlation. Therefore, it is under­ was taken as a basis for this subdivision, and standable that the Heerlen congresses should the Eumorphoceras (E), Homoceras (H) and have selected the most prominent marine Reticuloceras (R) zones were taken as the bands as the boundary horizons between component parts of the Namurian Stage. the A, B and C subdivisions of the West­ The second congress (1935) recognised that phalian. If one is only dealing with paralic the lower part of the Gastrioceras Zone (Gi) coal-measures formed on slowly subsiding was also included, and introduced A, B and shelf areas, the eustatic transgressions can be C divisions corresponding to the E-H zones distinguished and used for inter-regional (Namurian A), Ri - R2 zones (Namurian B) correlation. However, in tectonically active and G1 Zone (Namurian C). Various areas areas as well as in predominantly marine were mentioned for the occurrence of these basins, these eustatic transgressions are less units, but no attempt was made, to regard any likely to produce distinctive horizons, and

239 in this case one can only correlate on the Neuropteris ovata group which are comprised predominant kind of fossil remains. For the under the term 'Mixoneura' as used by paralic coal-measures of north-western Europe BERTRAND. A later recommendation by the these are generally plants and, in some cases, Subcommission on Carboniferous Strati­ non-marine bivalves. The boundary between graphy (VAN LECKWIJCK 1964C), following the Westphalian B and C, placed at the Aegir a proposai made by W. REMY, emphasised Marine Band by the first Heerlen congress and the biostratigraphic aspect by stating that the maintained at this horizon ever since, has base of Westphalian D should coïncide with been criticised by BouRoz et al. (1969) as the first occurrence of Neuropteris ovata. being irrelevant in terms of floral and faunal The Westphalian D thus became the first changes which would operate at a different chronostratigraphic unit linked unequivocally horizon in the succession. lt is true, of course, to a fossil plant occurrence. It is always a that a physical boundary between strati­ Iittle worrying if a chronostratigraphic boun­ graphie units in a succession used as a dary is linked to the incoming of a single standard for correlations further afield should taxon, but a revision of the floral elements be selected in such a manner that its ap­ found in the vicinity of the first occurrence proximate position can be established else­ of Neuropteris ovata in Lorraine (the con­ where. In other words, it should also be a ceptual type area of the Westphalian D convenient boundary between floral and/or Stage) bas shown that important changes in faunal zones. Regrettably, this point was floral composition occur both below and not considered when the Aegir Marine Band above the level of this first occurrence was selected as the Westphalian B/C boun­ (LAVEINE, in press). Although the passage dary, and one must wonder if this may im­ from one floral zone to another is graduai pair the usefulness of this horizon when (as can be expected in a continuous sequence correlations are attempted with areas out­ of strata showing similar facies throughout), side north-western Europe. On the other hand, the first occurrence of Neuropteris ovata a major eustatic transgression should have may well be used in the eventual selection of an a widespread effect all over the world. agreed stratotype for the Westphalian D Stage. The recommendation made by the Subcommission on Carboniferous Strati­ Westphalian D graphy during its meeting in Paris, 1963, In the paralic coal-measures of north­ may therefore be allowed to stand. western Europe there are no obvious marine It is understandable that the definition of bands above the horizon of the Top Marine Westphalian D was linked to floral zones, Band in mid-Westphalian C. The boundary for the Saar-Lorraine Coalfield, serving as the between Westphalian C and D is therefore conceptual type area, shows entirely non­ not at any marine horizon. The position of marine coal-measures of upper Westphalian this boundary has been the subject of con­ age. This coalfield occupies an isolated posi­ troversy as the result of an ambiguity in the tion near the northern margin of the Mid­ definition of the Westphalian D unit. On the European Chain, and its upper Westphalian one hand, the Westphalian D was referred and Stephanian strata were formed indepen­ to as equivalent to the 'Zone à Mixoneura' dently from the paralic coal-measures area of BERTRAND but, on the other band, it was of north-western Europe. Within the Saar­ regarded as being represented by the Assise Lorraine Coalfield the Westphalian C and D de la Houve in Lorraine (compare BERTRAND coal-measures are overlain disconformably 1937). In a recent report on the Westphalian by Stephanian deposits consisting of three D, delivered by J. P. LAVEINE in Prague 1973, grey coal-bearing intervals in a red bed it was pointed out that this implied a contra­ succession. These coal-bearing intervals were diction since the basal part of the Assise de la correlated across to central France with Houve does not contain the elements of the Stephanian A, B and C.

240 Stephanian de la Peronnière, are rather incomplete and Since this is the only area in north-western there has been a tendency to regard the better Europe where Stephanian strata overlie known floral assemblages of the Zone de Westphalian D rocks (albeit disconformably), Lentin of Carmaux, on the southern edge of the Saar-Lorraine region has played an im­ the Massif Central, as characteristic of portant role in the definition of the West­ Stephanian A. It is in the Carmaux Coalfield phalian/Stephanian boundary. In fact, the where the Stephanian A/B boundary was lowermost Stephanian rock unit in Saar-Lor­ described most recently (DoUBINGER & raine, i.e. the Holz Conglomerate, was VETIER 1969) in terms of the floral succession, accepted by the Heerlen congresses of 1927 which is particularly well developed in that and 1935 as forming the boundary between area. However, the Zone de Lentin at Car­ Westphalian and Stephanian. This decision maux is later in age than the Faisceau de la sowed the seeds of confusion because it im­ Peronnière at Rive-de-Gier (Loire), whilst plied that there were two different type areas it should also be noted that the Stériles de for the Stephanian, viz. one in the St. Etienne Gagnières, at the base of the Stephanian (Loire) Basin of central France and the other strata of the Cévennes, were deposited even in Saar-Lorraine. earlier than the Stephanian A of Rive-de-Gier The historical stratotype of the Stephanian (BouRoz 1972). The Stériles de Gagnières is in the Loire Basin where it comprises the contain only sporadic, drifted plant remains succession from the Assise de Rive-de-Gier as well as non-marine faunal elements of to that of the Bois d'Avaize inclusive, and limited zonal value. the term was stated to apply generally to the Admitting the fact that Stephanian A, coal-measures on the eastern side of the B and C related primarily to the Assise Plateau Central (MuNIER CHALMAS & DE de Rive-de-Gier, Assise de St. Etienne, and LAPPARENT 1893, p. 451). The Stephanian Assise d'Avaize of the St. Etienne (Loire) succession in the Loire Basin consists of Coalfield, one may doubt the accuracy of the three parts, viz. the Assise de Rive-de-Gier, correlation with Stephanian A, B and C, as the Assise de St. Etienne, and the Assise distinguished in the Saar-Lorraine area. d 'Avaize. These formations have been equated There is reason to venture the opinion that the with Stephanian A, B and C by PRuvosT basal part of the so-called Stephanian A of (1934, p. 112) and JoNGMANS & PRUVOST Saar-Lorraine is correlatable to the Zone de (1950). In the St. Etienne Coalfield, as else­ Lentin of Carmaux rather than the Faisceau where in central and south-central France, de la Peronnière of Rive-de-Gier. It is also the Stephanian strata lie with angular un­ apparent that the top part of Stephanian A conformity on the metamorphic and intrusive in Saar-Lorraine should be assigned to early rocks of the Massif Central. It is also known Stephanian B in terms of the floral succession that the basal Stephanian deposits are of known from the Massif Central (compare different ages in different parts of this general GERMER et al. 1968). area. The detailed correlations made most The absence of Westphalian deposits in the recently on the basis of cineritic tonstein Massif Central has made it impossible to bands in the different coalfields of this area establish the relationship between West­ (BoURoz 1972), have shown without any phalian and Stephanian in that area. However, doubt that the earliest Stephanian strata the classical Stephanian floras of central of the Massif Central are in the Cévennes France are quite different to those of the region. Unconformable Stephanian deposits Westphalian, and although some of the were formed here in advance of those found difference may be ascribed to habitat and at Rive-de-Gier in the Loire Basin, where palaeogeographical considerations, there is the typf? Stephanian A is situated. The -Iforas likely to be a substantial time gap between of the Assise de Rive-de-Gier, found in the the two series as originally described. Also brief coal-measure interval known as Faisceau in the Saar-Lorraine Coalfield, where the

241 Stephanian is in superposition with upper proposed by DOUBINGER (1956) for the Westphalian strata, there is a stratigraphie 'étage ambigu autuno-stéphanien' of GRAND' gap associated with the Holz Conglomerate. EURY (1877), which formed a transition to the Although the presence of a discontinuity Autunian. Most recently, a modified proposai at the level of the Holz Conglomerate has for the recognition of a Stephanian D Stage been admitted for some time (compare, for has been presented by BoUROZ & DOUBINGER instance, JoNGMANS & GoTHAN 1937, p. 23), (in press). the size of the stratigraphie gap associated The recognition of the Stephanian and of with the Westphalian/Stephanian boundary its constituent units relied almost entirely on in Saar-Lorraine remained the subject of fossil floras which showed a general compo­ debate until very recently (GERMER et al. sition different to that of Westphalian fi.oral 1968, BoUROZ et al. 1972). It is now recognised assemblages. Graduai changes were recorded as being of sizeable proportions, equal to at from lower to upper Stephanian, but the least a full division of either the Westphalian general aspect of the classical Stephanian or the Stephanian series. fl.oras is a distinctive one if compared to the In fact, the only continuous succession of Westphalian fl.oras. The marked difference upper Westphalian and lower Stephanian between the Westphalian and Stephanian strata in western Europe has been described fl.oras is at least partly due to a difference most recently from north-western Spain, in age, and this has become very apparent since a little known area at the time when the Holz the substantial size of the stratigraphie break Conglomerate was designated as the West­ associated with the Holz Conglomerate phalian/Stephanian boundary horizon. The in Saar-Lorraine has been realised. However, much more complete Spanish succession has the difference in composition between West­ allowed gauging the stratigraphie gap existing phalian and Stephanian fi.oral assemblages below the Holz Conglomerate, and this gap are also due to some extent to the different has proved to be a very substantial one. The palaeogeographic setting of the original result of the investigations in Spain has been Westphalian and Stephanian type areas. to designate a stage, the Cantabrian Stage, JoNGMANS (1952) made a distinction between following upon Westphalian D and preceding paralic, paralo-limnic and limnic basins, and Stephanian A (WAGNER 1966). This stage he employed the term 'Westphalian E' for has been assigned to the Stephanian Series, those fl.oras of Stephanian age which occurred in view of the fact that it corresponds at in paralic and paralo-limnic basins. The least partly to the lower Stephanian of the fl.oras of the intramontane limnic basins of Cévennes, shown to be earlier than Stepha­ central France were thus set apart quite nian A. A stratotype for the Cantabrian Stage clearly. Although his choice of the term has recently been designated in the province of 'Westphalian E' was unfortunate (since a Palencia, N.W. Spain (BoUROZ et al. 1972). difference in fi.oral facies was meant and not The same area has provided a new boundary­ a chronostratigraphic difference), the dis­ stratotype of the Stephanian A Stage (GEORGE tinction is a valid one, from the palaeo­ & WAGNER 1972). geographical point of view as well as that of The Stephanian, as based on the rocks in local habitat. Floras of the coastal plain central France, has always caused the greatest are richer in species, probably as a result of difficulties in correlation. The first and second better opportunities for migration and the Heerlen congresses failed to discuss its consequent mixing of fl.oras, whilst the intra­ subdivision, and it was not until the note montane areas show a smaller number of published by JONGMANS & PRUVOST (1950) species among which there are endemic that the Stephanian A, B and C divisions elements. It is also noted that the paralic and became established (to which the Canta­ paralo-limnic basins of Stephanian age show brian division has been added later). A a higher proportion of true ferns (Pecopteris further division, the Stephanian D, was and Sphenopteris) and generally rare remains

242 of gymnosperms, whereas the latter are quite of saccate pollen (ca. 80 %) in the microflora. diversified in the intramontane Stephanian The Stephanian D division of the same authors floras. Pteridosperms occur in bath floral shows the first appearance of Callipteris in the facies, but the proportion of occurrences context of an upper Stephanian macrofloral may be quite different. In the intramontane assemblage, whilst the microflora shows basins there may be a relatively high propor­ relatively few saccate pollen (ca. 10%) and a tion of species which lived in drier hill slope predominance of monolete and trilete spores and upland environments. Altogether, there (ca. 80%). This amounts to a revision of the can be sharp differences in the composition Stephanian/Autunian boundary, with due of coastal plain (paralic and paralo-limnic) reference to the Stephanian and Autunian and intramontane (limnic) floral assem­ type sections in central France. The proposais blages. JoNGMANS (1952) emphasised the made by BOUROZ & DOUBINGER will have to be common presence of Neuropteris ovata in the discussed during the next meeting of the paralic and paralo-limnic basins of Stepha­ Subcommission on Carboniferous Strati­ nian age, whereas this species is exceedingly graphy in conjunction with the broader issue rare and practicaily absent in the in tramontane of the Carboniferous/Permian boundary basins of the classical Stephanian of central which is linked, to a large extent, to marine France and of Saar-Lorraine. Much has been faunas. made of Neuropteris ovata, and BODE (1973) even goes so far as to insist that the biozone of Criteria for the definition of Upper Carboni­ Neuropteris ovata should be regarded as equi­ ferous stages valent to a single, basic chronostratigraphic unit. Such an extreme point of view would It will be clear from the preceding chapter result in the Jumping together of Westphalian that the stratigraphie scheme elaborated by D, Cantabrian, Stephanian A and Stephanian the Heerlen congresses and modified sub­ B with part of Stephanian C into a single sequently by the Subcommission on Car­ unit, and it is difficult to see what advantage boniferous Stratigraphy consists of units could possibly be gained. The top occurrence which have been based on a variety of of Neuropteris ovata is found in rocks of quite criteria. different ages in different parts of the world For the Namurian Series the various (as bas been pointed out already by several subdivisions were straight biozones which authors), and it is clear that this species have been converted afterwards into stages by provides one of the best examples of the the formai designation of type sections. These inadvisability of linking a chronostrati­ stratotypes aIIow correlation by means of graphic unit to a single taxon. several biological groups, among which go­ niatites take pride of place. In fact, the stage Stephanian D/ Autunian boundaries have been made to coincide with The upper limit of the Stephanian is a the boundaries between the goniatite zones. problem that is usually solved by reference However, the stratotypes also provide cono­ to the first occurrence of Callipteris which is donts and miospores as additional correlatory taken as indicating the presence of Rotliegend elements of importance. These stratotypes are or Autunian (JONGMANS & GOTHAN 1937, useful and accessible, and it only needs some p. 24, REMY 1964). However, a more marked additional reference sections with macro­ change in floral characteristics occurs at a floral assemblages and different ones con­ somewhat higher Ievel, and BoURoz & taining foraminiferal remains in limestone DoUBINGER (in press) have recently suggested facies, in order to obtain a broad spectrum that the base of the Autunian should be placed of correlatory elements. at the Assise de Muse of the Autun Basin. The Westphalian stages A, B and C were The Assise de Muse shows several species of based on rock sequences which relied for Callipteris as well as a marked predominance correlation on the lower boundary horizons,

243 i.e. the marine bands representing widespread below the Holz Conglomerate in Lorraine. eustatic transgressions. Additionally, the Since this is an entirely non-marine succession, fossil contents of the intervening coal­ one looks mainly to the floras tor correlation measures were available for correlation, but further afield (the use of cineritic tonstein no attempt was made here to make the stage bands, though extremely valuable for correla­ boundaries coincide with zonal boundaries(5) tion with areas even as far away as the Nord­ There is only a limited number of biological Charleroi Basin in the Franco-Belgian border groups that can be used for correlations with region, is unlikely to be successful for long those regions which are not on the relatively range correlation). It is understood that the stable shelf areas susceptible to the effects of a Saar-Lorraine Coalfield is not in itself like­ eustatic rise of sea level. These are primarily ly to furnish the Westphalian D stratotype, floras (both macro- and microfloras) with despite its historical connection. The Assise non-marine bivalves, the marine faunas de la Houve in Lorraine is only known from of the sporadic marine bands serving mainly subsurface exposures, which are only tem­ to identify the individual transgressions. porarily accessible, and its equivalent strata The latter can hardly be used for a zonal in Saarland are too little exposed on the scheme, since the total ranges of the (fairly surface to be seriously considered for strato­ restricted) marine faunal elements present typic purposes. Also, the Saar-Lorraine cannot be established from the sporadic Basin is rather isolated palaeogeographically marine intervals that have been recorded on and thus contains a number of endemic plant the shelf areas. Only boundary-stratotypes species. It also shows the absence or near­ have been recognised thus far, and these absence of other species likely to provide are likely to be selected in localities of the East correlation with other areas where West­ Pennine Coalfield of England (GEORGE & phalian D strata occur. The sequence in WAGNER 1972). These stratotypes have not Saar-Lorraine is also totally non-marine, been recognised in Westphalia because the thus imposing a restriction on the number of 'Richtschnitte' (standard· sections) for the biostratigraphic elements available for inter­ Westphalian A, B and C stages in western regional correlation. However, its floral Germany are in coal mines and are, therefore, assemblages are sufficiently similar to those not permanently accessible. There is an occurring elsewhere in Westphalian D strata, obvious need for additional reference sections to provide a starting point for correlations providing more complete marine faunas, with the ultimate aim of selecting a suitable particularly with regard to fusulinid fora­ stratotype in a different region but without minifera and brachiopods. The problem will changing fundamentally the chronostrati­ be one of correlation between the predomi­ graphic interval as originally described from nantly terrestrial stratotypes and the mainly Saar-Lorraine. This is the method adopted by marine reference sections which, in western the Working Group on Westphalian D, (and central) Europe, can only be found in led by J.P. LAVEINE, who has already provided north-western Spain. a revision of the Westphalian D flora of The Westphalian D Stage, for which no Lorraine, and who is presently engaged in formal stratotype bas been designated as yet, the attempts at correlation which should is linked at its lower boundary to the first precede the selection of the definitive strato­ appearance of Neuropteris ovata. The concept type. This method may well be regarded as the of Westphalian D is historically linked to proper procedure to follow in any study the upper part of the coal-measure succession leading towards the designation of an inter­ national stratotype. The unsatisfactory boundary between the ( 5) In Britain the non-marine bivalve zonal boundaries were everywhere put at levels Westphalian and the Stephanian series, coincident with the stage boundaries (marine which was selected at the Holz Conglomerate bands) and other prominent marker bands. of Saar-Lorraine by the Heerlen congress

244 of 1935, has been abandoned in favour of a System. This stage, with a stratotype in the new boundary-stratotype selected between St. Etienne (Loire) Basin, would be charac­ upper Westphalian D and lower Cantabrian terised by the first appearance of Callipteris (basal Stephanian) in a continuous sequence in the context of a Stephanian C flora. of strata in north-western Spain. The well­ The purely terrestrial environment imposes exposed type section of the Cantabrian Stage the same limitations on the flora, as men­ in the Cordillera Cantâbrica is perhap~ the tioned before, with the additional peculiarity most adequate of all the Upper Carboniferous that the Autunian (or Rotliegend) saw a stratotypes adopted thus far. It contains al­ widespread climatic change in Europe as ternating marine and terrestrial strata which the result of which the humid coal-measure allow correlations on the basis of several environment was replaced by a much drier groups of fossils, including fusulinid foramini­ habitat. In any particular area this climatic fera, brachiopods and land plants (WAGNER change is likely to have had a dramatic effect et al. in press). The floral assemblages of the on the general composition of the flora, thus Cantabrian stratotype show a general com­ providing a clearly marked biostratigraphic position similar to that of paralic Westphalian boundary which can be used for the selection floras, as the result of a similar kind of of a chronostratigraphic boundary-stratotype. environment. There is a gradua} transition Indeed, such a changeover has been recorded upwards from the upper Westphalian D floras by BoUROZ & DOUBINGER (in press), particu­ into the lower Cantabrian ones, and no abrupt larly with regard to the microflora, and they changeover as happens in a discontinuous have proposed a boundary-stratotype be­ sequence, either as the result of a stratigraphie tween Stephanian D and Autunian, which break (as in Saar-Lorraine) or of a marked takes this into account. However, there is no change in the environment. guarantee that such a climatic change would The boundary-stratotype of the Stephanian operate synchronously in different parts of the A Stage has also been chosen in north-western world or even in different parts of Europe. Spain, and it also shows marine and terrestrial In fact, this is most unlikely, and it is known strata which allow for adequate long range that there are certain places in the world (e.g. correlations. China and Korea) where this changeover The stratotypes of the other stages in the did not take place and where floras of a humid Stephanian Series have not yet been de­ habitat continued to be present and evolved signated. The traditional type area of the gradually throughout Permian times. The Stephanian B and C stages is the Loire Basin, normal successor to the Carboniferous coal­ but this suffers from an exclusively terrestrial measure floras is found in the Cathaysian facies in an intermontane (limnic)basin. Province. Only the Alpine region seems to Therefore, only the fossil flora and occ~sional contain marine strata of ages equivalent elements of non-marine fauna are available to Stephanian and Autunian, but the effective for long range correlation. Stratotypes in this correlations have not yet been made for more area would undoubtedly suffer from the than the occasional locality, and it is unlikely restrictions imposed by a single group of that the Alpine region will be capable of fossils being the only one available for effec­ providing reasonable stratotypes in view of tive correlation, and within this group one its intricate tectonic structure. would have to take into account the effect of It is realised that the question of the Ste­ endemic species and a general composition of phanian/Autunian boundary is likely to be of the flora which reflects the special palaeogeo­ relatively local interest, and that the main graphical position and the local habitats. problem will centre on the Carboniferous/ The Stephanian D Stage, as proposed most Permian boundary on a world-wide basis. recently by BoUROZ & DOUBINGER (in press), The latter may well be quite different in forms the transition to the Autunian which position to the Stephanian/Autunian boun­ may or may not be part of the Permian dary, and it is difficult to see how western

245 Europe, with its special palaeogeographical the wider correlations one has to use the conditions, may effectively contribute to the biological elements, however imprecise the solution of this problem (compare BoURoz & boundaries between biozones may be. There­ DouBINGER, in press). fore, it is of considerable importance to avoid selecting stratotypes in areas showing only a limited range of facies. The selection of stratotypes with regard to an integrated european scheme of Carboniferous Present West European stratotypes chronostratigraphic units At present, a fairly large number of chrono­ General stratigraphic units in the Carboniferous of From the discussion so far, it is evident western Europe are still based on rocks in that the criteria used for the recognition of limited facies. In the case of the Namurian stages in the different parts of the Upper stratotypes, one regrets the almost complete Carboniferous sequence in western Europe absence of plant macrofossils, and one should have differed quite markedly, with regard consider the possibility of selecting auxiliary to the special facies and palaeogeographic reference sections which are fully correlated conditions operating in the regions first with the stratotypes and which do contain the studied. This has tended to produce a patch­ macrofloras. On the other hand, the Namurian work of chronostratigraphic units relying for stratotypes are better than most in containing their correlation on quite different bio­ goniatite and conodont faunas as well as stratigraphical or even lithostratigraphical abundant and well preserved microfloras. criteria. The multiplicity of approaches used Much more serious is the position with for the recognition of the various stages has regard to the Westphalian and most of the been moderated to some extent by the efforts Stephanian stratotypes. As the matter stands of the 1.U.G.S. Subcommission on Carboni­ at present, the Westphalian A, B and C ferous Stratigraphy which is concerned with stratotypes remain in the belt of paralic the selection of stratotypes for these chrono­ coal-measures on the margin of the North stratigraphic units and with the application Atlantean Continent of northwestern Europe. of similar criteria to ail of them. A certain For the correlations within this area reliance consensus on these criteria has emerged. is placed mainly on the principal marine bands It is clear that a stratotype will have to be which provide accurate lithological markers. permanently accessible as a standard reference On the world-wide scale, however, the elements section for correlation, and that this implies of correlation available in these stratotypes good permanent exposure. Temporary ex­ are macro- and microfloras, together with posures in coal mines and boreholes, however non-marine bivalves. It is doubtful that these well studied, are obviously not acceptable for can be regarded as totally adequate since the stratotypic purposes. A stratotype will also range of biological groups available is be of limited use if it contains only a limited strictly limited. The general absence of range of facies, since this implies only a limited marine faunas is a serious drawback which number of biological groups capable of cannot be offset by the sporadic and rather providing the elements of long range corre­ limited faunas present in the marine bands. lation. Marker bands, however widespread The Westphalian D Stage, which was and important for a fine correlation on the originally based on the sequence in the Lorrai­ regional scale (e.g. marine bands formed as ne Coalfield, can only be identified effectively the result of eustatic transgressions, and cineri­ by means of fossil floras. A stratotype has tes produced by large emissions of volcanic yet to be designated, and is certainly to ash), cannot furnish more than convenient be found outside the Saar-Lorraine Coal­ boundaries between stratigraphie units in field since this area is not only deficient in the more or less comprehensive local areas. For range of fossils available but also in the

246 amount of exposure which is mainly in coal Spain the Stephanian B and C strata were laid mines. down in a coastal basin, with predominantly The top of the Westphalian Series is deter­ non-marine facies but showing occasional mined by the base of the Cantabrian Stage, marine influences. A more marine develop­ the basal chronostratigraphic unit of the Ste­ ment of Stephanian B and C is present in the phanian Series. The Cantabrian Stage has an Carnic Alps (Austria/Italy). It is clear that the adequate stratotype in north-western Spain Stephanian B and C strata of both the Carnic where alternating marine and terrestrial de­ Alps and north-western Spain will have to be posits, both abundantly fossiliferous, provide considered for the designation of effective the elements of correlation not only with stratotypes for these two stages. western Europe (e.g. the Cévennes region of The Stephanian D Stage, as proposed most southern France) but also with European recently by BoURoz & DoUBINGER (in press), Russia and North America. forms a transition to the Autunian. Its biostra­ The Stephanian A Stage has a designated tigraphic elements are entirely non-marine boundary-stratotype in north-western Spain, (mainly macro- and microfloras). in the same section which also provides the If one looks towards a future integration stratotype for the upper Cantabrian. The full of the West European and Russian chrono­ extent of the Stephanian A Stage remains stratigraphic units, it will be necessary to to be determined, since the boundary­ provide first of all the elements of correlation stratotype of Stephanian B has not yet been between these two different sets of units. designated. The Stephanian A in Spain is also In part, these elements are present in the form partly marine, and its lower part contains of land plants and the occasional goniatite bracbiopod and other marine faunas capable faunas in the Russian and West European of providing correlation with the U.S.S.R. sequences. However, most of the Russian and North America. It also contains the chronostratigraphic units are based on se­ floral elements necessary for the correlation quences with marine faunas including fusu­ with the rocks traditionally regarded as linid foraminifera. Within western Europe Stephanian A (e.g. the Zone de Lentin of these foraminiferal faunas are only present in Carmaux) in central France. north-western Spain and in the Carnic Alps. The Stephanian B and C stages have not The same areas also contain the additional yet corne up for scrutiny by the Subcommis­ marine faunas, such as brachiopods, gastro­ sion on Carboniferous Stratigraphy. Their pods, bivalves, ostracodes, corals and bryo­ traditional type area is in the St. Etienne zoans, which play a subsidiary rôle in the (Loire) Basin, which is entirely non-marine recognition of the Russian units. Goniatites and one of the classical limnic basins of are also present, albeit in small numbers. central France. The Stephanian B and C strata fo1,1nd in the intramontane basins of central N. W. Spain, a link with the Russian Car­ France are unsuitable for stratotypes. Not boniferous (Table 3) only do they offer a very limited range of fossils for correlation (i.e. macro- and micro­ Of the two areas mentioned, the Cantabrian floras together with occasional fish faunas Cordillera of N.W. Spain stands out as and other non-marine animais), but the containing the most complete Upper Car­ classical Stephanian B and C floras of central boniferous successions, with the richest France are rather special as a result of their marine faunas and terrestrial floras. The palaeogeographical position and the nature stratigraphie sequences of this area are quite of the limnic basins found well within the well known and capable of being studied in hinterland area of the Mid-European Chain. great detail. The exposures are very good and Most of the Stephanian basins in western the predominantly isoclinal folding has pro­ Europe are of a similar nature and show vided long sections within relatively small comparable drawbacks. Only in north-western areas. The Alpine sequences may be less corn-

247 TABLE 3 Approximate correlation of West European and Russian chronostratigraphic units as suggested by the evidence in N.W. Spain

U.S.S.R. UNITS WEST EUROPEAN ------STAGES (Upper Carboniferous only) Substages Stages Series

1 1 Stephanian C -- Stephanian B Gzhelian sensu stricto UPPER Stephanian A GZHELIAN CARBONIFEROUS ·------Kasimovian Cantabrian

·--- Myachkovian 1 Westphalian D ---- 1 --··--- Podolskian Westphalian C MOSCOVIAN Kashirian Westphalian B 1 MIDDLE CARBONIFEROUS Vereyan Westpha!ian A 1 BASHKIRIAN Yeadonian 1 ------Marsdenian LOWER Kinderscoutian "NAMURIAN" CARBONIFEROUS

Alportian 1

Chokierian

-- --·~- ---- Arnsbergian

Pendleian

plete and are less easily studied because of more suitable for stratotypic purposes in this the tectonic complexity of this area. area of north-western Europe). On the con­ It would make good sense to try and to trary, in N.W. Spain both the various stages select stratotypes for the maximum number of the Westphalian and the two stages of the of stages in the Westphalian and Stephanian lower Stephanian (Cantabrian and Stepha­ series as exposed in the Cantabrian Cordillera nian A) are developed in marine facies inter­ of N.W. Spain. Both the Westphalian and leaved with terrestrial deposits, thus providing Stephanian series are developed in a limited excellent stratotypes with a wide range of facies range in the classical areas of Britain, fossil organisms. The macro- and micro­ Germany, France and Belgium (unlike the floras present in the Spanish rocks are ade­ Namurian which shows a development much quate for a reasonable correlation with the

248 classical Westphalian successions of north­ American units on the other. This correlation western Europe. The proximity of the Spanish had to rely mainly on floral evidence from area to north-western Europe also ensures the Donetz Basin for its comparisons with the a more immediate correlation with the various stages of the Westphalian in north­ traditional Westphalian successions than western Europe. Goniatite faunas were very may be possible between the latter and a few and far between in both areas, and pre­ more distant region, such as the Donetz cious few other marine faunas were known Basin. The fusulinid foraminifera and other from north-western Europe. The fusulinid­ marine faunal elements which are çresent bearing limestones of the Donbass sequence in such abundance in the Spanish Carbonife­ provided the mainstay of correlation with the rous, provide the means for an instant cor­ Moscow Basin, with its Moscovian divisions relation with the Bashkirian, Moscovian and of Vereyan, Kashirian, Podolskian and Kasimovian to Gzhelian units of the Russian Myachkovian. The correlations proposed classification. They also allow correlation by the Russian Committee excited widespread with the marine successions of the North interest and they have often been applied American Continent. One does not need to since (e.g. for the Fossi! Record published stress that Spain occupies a key position by the Geological Society of London), geographically, sited, as it is, between the without having been submitted to a critical Russian and North American areas, and examination. belonging to western Europe. In the Cantabrian Cordillera of N W. Spain, The combined occurrence of fully marine where marine faunas allow a direct correlation faunas and continental floras in the Car­ with the Moscow Basin and where the macro­ boniferous of N.W. Spain, and the consequent and microfloras exist for an immediate opportunities for a world-wide correlation, comparison with north-western Europe, the have been known for some time. DELEPINE Russian correlation was inevitably put to the (1938) presented the first general correlation test. It soon became evident that certain between Russia, N.W. Spain and north­ parts of the proposed correlation were less western Europe. However, only a limited convincing than others. The first doubts were knowledge of the Spanish faunas. and floras expressed by w AGNER & w AGNER-ÜENTIS had been gained at that time, and his correla­ (1963) and soon afterwards VAN GINKEL tion thus remained highly tentative. This (1965) proposed certain emendations to the situation has now changed considerably. Russian correlation scheme. VAN GINKEL's Over the last twenty years great strides have emendations were based primarily on the been made in the investigation of Carboni­ evidence of fusulinid faunas identified by ferous strata in N.W. Spain, and even though himself and on published records of macro­ some parts of the Cantabrian Cordillera are floras studied by the present writer. Most of still not known in detail, other parts of this the information available to VAN GINKEL mountainous area with its well exposed, came from spot samples taken from succes­ long and uninterrupted sedimentary sequence sions which were not always fully understood. of Upper Carboniferous rocks are now known Consequently, the proposed emendations just as well, if not better, than some of the were perhaps a little premature. classical regions in north-western Europe. The difficulties centred on the lower and In 1958, at the fourth Heerlen congress, upper limits of the Bashkirian Stage. The the Commission on the Stratigraphy of the Russian Committee had correlated its base Carboniferous of the National Committee with the base of Namurian C, and its top of Soviet Geologists (STEPANOV et al. 1962) with the limit between Westphalian Band C. presented a correlation between the units VAN GINKEL (1965) proposed that the base of two classical Russian sequences on the one of the Bashkirian should be lowered to the hand (viz. of the Donetz and Moscow base of Namurian B or to a position within basins), and West European and North Namurian A, and that the top of the Bashkiri-

249 an should also be lowered, viz. to a position The upper Cantabrian is clearly of Kasimo­ coinciding approximately with the Namurian vian age on both the brachiopod and fusulinid C (Yeadonian) and Westphalian A boundary. faunas. VAN GINKEL (1972) has further sug­ A more comprehensive study of the various gested that the top of the Kasimovian would elements of flora and fauna (including mio­ lie within Stephanian B, but this conclusion spores, sporadic macrofloral remains, fora­ is still highly tentative in view of the limited minifera, goniatites and brachiopods) ob­ floral evidence associated with the fusulinids tained from a single succession of strata in of the Triticites Zone in Spain. northern Le6n (MOORE et al. 1971) provided It is clear that the Spanish Carboniferous a useful check on VAN GINKEL's suggestions. bas a vital rôle to play in the correlation be­ It proved that the Russian correlation ap­ tween the chronostratigraphic units in western peared to be substantially correct in equating Europe and in the U.S.S.R. Additional the lower Bashkirian with at least part of work in Spain as well as in the U.S.S.R. Namurian C. On the other hand, the top of should allow further precision, and it is also the Bashkirian (and consequently the base of desirable that the Carnic Alps should be drawn the Moscovian) was certainly to be placed in into the process of correlation, particularly a position lower than that suggested by the with regard to the higher stages of the Ste­ Russian correlation, although perhaps not phanian and the Gzhelian and Orenburgian quite as low as proposed by VAN GINKEL. stages of the Russian Upper Carboniferous. The second subdivision of the Moscovian, At present, the evidence obtained from i.e. the Kashirian, was found to be equivalent N.W. Spain suggests the following correla­ to most of the Westphalian B and the lower tion as being the most probable (compare part of Westphalian C. The exact position WAGNER & WINKLER PRINS in WAGNER of the Bashkirian/Moscovian (Vereyan) boun­ 1971, p. 36) (Table 3). dary could not be established on the Spanish evidence but it seems likely to fall within the Conclusions Westphalian A division of the West European classification. This amounted to a substantial 1. The West European chronostratigraphic revision of the Russian correlation scheme units for the Upper Carboniferous, historically and it proved that the elements of the correla­ based on a variety of biostratigraphical and tions proposed by the Russian Committee lithological criteria, are currently being should be submitted to a careful analysis re-examined by the I.U.G.S. Subcommission before it is put into operation. With regard on Carboniferous Stratigraphy, and put on a to the upper limit of the Moscovian, it more equal footing by the designation of a was suggested by STEPANOV et al. (1960) that stratotype for each stage. The stages within the Myachkovian/Kasimovian boundary the Namurian Series show a reasonably should coïncide with that between Westpha­ adequate number of biological elements in lian D and Stephanian. This conclusion has their stratotypes for the latter to be effective, been proved substantially correct, but the even though auxiliary reference sections may recent recognition of the Cantabrian Stage be recognised as well. The stratotypes for at the base of the Stephanian Series in western Westphalian A, B and C, historically situated Europe has provided further precision. on the shelf of the North Atlantean Continent Fusulinid faunas as well as brachiopod and in the Variscan marginal trough, should assemblages obtained from the Cantabrian probably be chosen outside these northern stratotype (VAN GINKEL 1972, WINKLER European regions which are deficient in PRINS in WAGNER & VARKER 1971, WAGNER terms of facies and in the number of fossil et al. in press) have suggested that the Myach­ groups available for correlation. The pre­ kovian/Kasimovian boundary lies within the dominantly marine succession in N.W. Spain Cantabrian, either in the lower part of this may, eventually, provide better stratotypes. stage or, more likely towards its middle part. The same is true, even to a larger extent, for the

250 Westphalian D, whichhas been based originally making it into the Middle Carboniferous unit on a non-marine sequence in Saar-Lorraine. containing the Namurian and Westphalian The stratotypes for the two lower Stephanian only (i.e. the old Westphalian of MUNIER stages, Cantabrian and Stephanian A, have CHALMAS & DE LAPPARENT). Since the already been designated in N.W. Spain. Namurian Series of western Europe comprises The Stephanian B and C stages, traditionally the upper part of the Russian Lower Car­ based on sequences in central France, can boniferous (Russian 'Namurian') and the be based more effectively on successions in lower part of the Russian Middle Carbonife­ N.W. Spain, but the sequences present in the rous (Bashkirian), it would be reasonable Carnic Alps should also be taken into con­ to request the Soviet Committee on Car­ sideration. boniferous Stratigraphy to transfer the 2. It should be a primary aim of the Russian Namurian to the Middle Carboni­ I.U.G.S. Subcommission on Carboniferous ferous, and to leave only the Dinantian in the Stratigraphy to study the possibility of an Lower Carboniferous. Otherwise, the Namu­ integrated scheme of Carboniferous chrono­ rien Series would be split asunder. Agreement stratigraphic units for all of Europe. This on the equivalence of the series in the West involves collecting information on the cor­ European and Russian chronostratigraphic relation of units recognised in western Europe schemes may facilitate future agreement on with those of the U.S.S.R. the constituent stages in an integrated Euro­ 3. Consideration may be given to the pean classification which should be regarded recognition of series in the West European as an attainable objective. Carboniferous in such a way as to facilitate a broad comparison with the Lower, Middle Acknowledgements and Upper Carboniferous of the Russian classification. This would involve classifying The writer is grateful to Drs. M.A. CALVER the Dinantian as a series (rather than a , and A.C. HIGGINS for constructive comments subsystem) and emending the Silesian by and suggestions.

TABLE 4 Major Carboniferous units in Europe (Lower and Middle Carboniferous boundary adjusted and rank of West European units revised in accordance with the proposais outlined in the present paper).

RUSSIAN SERIES WEST EUROPEAN SERIES

Upper Carboniferous Stephanian (Gzhelian, Orenburgian)

- "--~------Middle Carboniferous Westphalian l Silesian ('Namurian', Bashkirian, Moscovian) Namurian J

Lower Carboniferous Dinantian (Tournaisian, Viséan)

251 REFERENCES

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