Tonstein Bands in the Coalfields of the East Midlands

Eden, R.A.; Elliot, R. W.; Elliott, R. E.; Young, Brent R.

doi:10.1017/s0016756800055047

Cited by 23 publications

(7 citation statements)

References 2 publications

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“…Detailed petrographic studies have been made of several British tonsteins (e. g., FRANCIS, 1961 ;FRANCIS andEWING, 1961,1962;EDEN et a]., 1963;BARNSLEY et al, 1966;SPEARS, 1966;STRAUSS, 1969). For this reason briefdescriptions only are given of the specimens listed in Tables I and 11.…”

Section: Mineralogy and Petrographymentioning

confidence: 99%

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Mineralogy and Chemistry of Tonsteins From Carboniferous Sequences in Great Britain

Price

Duff

1969

Sedimentology

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SUMMARY Tonsteins from Westphalian Coal Measures in England are compared mineralogically and chemically with tonsteins of volcanic origin from coalbearing sequences of Namurian and Westphalian age in Scotland. Differences are apparent between tonsteins occurring as partings within coals (“coal tonsteins”) and those interbedded with inter‐seam sedimentary rocks (“non‐coal tonsteins”). The coal tonsteins show higher titanium values and in some cases contain minerals of the goyazite series. Sedimentological, mineralogical and chemical evidence is reviewed and the conclusion reached that all tonsteins examined could have originated as thin layers of volcanic ash. Subsequent alteration depended upon the environment of deposition into which the ash fell.

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Section: Mineralogy and Petrographymentioning

confidence: 99%

“…WILLIAMSON'S (1 961) review of tonstein occurrences in continental Europe stimulated the publication of much that was known of tonsteins in Britain and led to considerable interest in them (EDEN, 1961;EDEN et al, 1963;SALTER, 1964;HOARE, 1965;BARNSLEY et al, 1966;SPEARS, 1966;WILSON et al, 1966;STRAUSS, 1969).…”

Section: Introductionmentioning

confidence: 99%

Mineralogy and Chemistry of Tonsteins From Carboniferous Sequences in Great Britain

Price

Duff

1969

Sedimentology

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“…The tonstein occurs a short distance above an important marine horizon, the Mansfield (Aegir) Marine Band. The tonstein has been correlated between different coalfields (Earp 1961;Eden et al 1963;Hoare 1965;Mayland & Williamson 1970;Worssam et al 1971) and named by reference to adjacent coal seams. It is therefore variously known as the Stafford, the supra-Wyrley Yard, the sub-High Main, the sub-Worsley Four Foot, the P27 and the Sharlston Muck.…”

Section: Bedformmentioning

confidence: 99%

“…Interest in British tonsteins was stimulated by Williamson's review of tonsteins (1961) which coincided with a period of active coalfield exploration. Tonsteins in British coalfields were reported and described by Francis (1961), Francis & Ewing (1962), Eden et al (1963), Salter (1964), Barnsley et al (1966), Wilson et al (1966), Mayland & Williamson (1970), Strauss (1971) and Worssam et al (1971). More geochemically and mineralogically orientated studies were undertaken by Spears (1966Spears ( , 1970Spears ( , 1971, (Price & Duff (1969), Spears & Rice (1973) and Spears & Kanaris-Sotiriou (1979).…”

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confidence: 98%

An update on British Tonsteins

Spears

Lyons

1995

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Tonsteins are thin mudstone beds composed of kaolinite that formed from the alteration of volcanic ash in coal-forming environments. In the Coal Measures of Britain, tonsteins have been recognized as volcanic in origin based on bedform, volcanic textures, field relationships with other volcanics, distinctive volcanic minerals and an igneous geochemistry. The sharp contacts, together with a contrasting composition with adjacent sediments and lateral continuity, are diagnostic of an altered air-fall volcanic ash. Passage into less altered volcanics and into a K-bentonite have both been shown in Britain. A more direct determination of volcanic origin is possible from the identification of volcanic minerals, whole-rock geochemistry and analyses of silicate melt inclusions in volcanic minerals such as/3 quartz. Once a volcanic origin is established the stratigraphic value of a tonstein is enhanced. Immobile trace elements in tonsteins also provide information on the tectono-magmatic setting of the parent volcano. Two tonstein groups are identified in the Coal Measures of Britain, one formed from basic (basaltic) ash of local origin and the other from acid (rhyolite or rhyodacite) ash, probably associated with distant Plinean or ultraplinean eruptions at a destructive plate margin to the south or southeast.

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“…In addition to the thick volcanic sequences in the Westphalian coal measures, there are other rocks of volcanic origin. The most important of these are the tonsteins, which have been recorded by a number of authors including Eden et al (1963), Barnsley et al (1966), Mayland & Williamson (1970) and Strauss (1971). Tonsteins are comparable with the K-bentonites in their lateral continuity and sharp contacts with the adjacent sediment, but differ signi®cantly in that they are composed of kaolinite.…”

Section: Introductionmentioning

confidence: 98%

Namurian bentonites in the Pennine Basin, UK – origin and magmatic affinities

1999

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Nine Namurian clay bands retrieved from boreholes in the northern part of the Pennine Basin are, on the basis of their petrography, mineralogy and geochemistry, shown to be volcanic in origin and are therefore bentonites. The bentonites, which have a fragmental texture, are normally graded and show rare preservation of shard textures, representing vitric tuff deposits that have been altered subsequently to clay‐dominated horizons. Crystals are a minor component of the bentonites, but biotite, in particular, is concentrated at the base of the beds. A clay mineral assemblage of mixed‐layer illite–smectite with subordinate kaolinite identifies most of the samples as K‐bentonites, but kaolinite dominates two samples that can be classed as tonsteins. Temporal variation of salinity within the depositional basin is suggested to explain these different clay assemblages. The major element geochemistry of the bentonites reflects their clay mineralogy and the compositions of diagenetic minerals present, the latter including pyrite, carbonates and hydroxyapatite. Enrichment of the bentonites in some trace elements (including Ba, Sr, Pb, Cu and Ni) can be related to the presence of the diagenetic minerals, but the extent to which the elements are added from external sources as opposed to being redistributed within the ash is unclear. Immobile trace element systematics suggest a rhyodacite/dacite composition for the original ash and derivation from the collision of plates, this being supported by evidence provided by the rare earth elements (REE) in one group of samples. However, in another group of samples, variations in REE concentrations may be caused by mobility of these elements during alteration. The chemistry of the Namurian bentonites contrasts markedly with that of the local Carboniferous volcanics but is comparable, in some respects, with one group of Westphalian tonsteins, although the latter are more rhyolitic in character. It is suggested that the Namurian bentonites and the Westphalian tonsteins of acid affinities originated from volcanic activity associated with a destructive plate margin in the Variscan externides and that the observed compositional trend may reflect magma evolution possibly related to the progressive east–west closure.

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Tonstein Bands in the Coalfields of the East Midlands

Cited by 23 publications

References 2 publications

Mineralogy and Chemistry of Tonsteins From Carboniferous Sequences in Great Britain

Mineralogy and Chemistry of Tonsteins From Carboniferous Sequences in Great Britain

An update on British Tonsteins

Namurian bentonites in the Pennine Basin, UK – origin and magmatic affinities

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