A geochemical and mineralogical investigation of some British and other European tonsteins

Spears, D. A.; Kanaris‐Sotiriou, R.

doi:10.1111/j.1365-3091.1979.tb00917.x

Cited by 107 publications

(46 citation statements)

References 16 publications

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“…As described by Spears [56,57], Dai et al [58,59], Zhou et al [60] and Zhao et al [43], "tonsteins" are partings derived from air-borne material of pyroclastic origin in the peat-forming environment. They have been found in some coal seams of SW China [15,43,[58][59][60].…”

Section: Volcanic Ash Inputmentioning

confidence: 99%

Mineralogical Characteristics of Late Permian Coals from the Yueliangtian Coal Mine, Guizhou, Southwestern China

et al. 2016

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This paper reports the mineralogical compositions of super-low-sulfur (Yueliangtian 6-upper (YLT6U)) and high-sulfur (Yueliangtian 6-lower (YLT6L)) coals of the Late Permian No. 6 coal seam from the Yueliangtian coal mine, Guizhou, southwestern China. The mineral assemblages and morphology were detected and observed by X-ray diffractogram (XRD), optical microscopy and field-emission scanning electron microscope (FE-SEM) in conjunction with an energy-dispersive X-ray spectrometer. Major minerals in the coal samples, partings and host rocks (roof and floor strata) include calcite, quartz, kaolinite, mixed-layer illite/smectite, chlorite and pyrite and, to a lesser extent, chamosite, anatase and apatite. The Emeishan basalt and silicic rocks in the Kangdian Upland are the sediment source for the Yueliangtian coals. It was found that there are several modes of chamosite occurrence, and precursor minerals, such as anatase, had been corroded by Ti-rich hydrothermal solutions. The modes of occurrence of minerals present in the coal were controlled by the injection of different types of hydrothermal fluids during different deposition stages. The presence of abundant pyrite and extremely high total sulfur contents in the YLT6L coal are in sharp contrast to those in the YLT6U coal, suggesting that seawater invaded the peat swamp of the YLT6L coal and terminated at the YLT6U-9p sampling interval. High-temperature quartz, vermicular kaolinite and chloritized biotite were observed in the partings and roof strata. The three partings and floor strata of the No. 6 coal seam from the Yueliangtian coal mine appear to have been derived from felsic volcanic ash. Four factors, including sediment-source region, multi-stage injections of hydrothermal fluids, seawater influence and volcanic ash input, were responsible for the mineralogical characteristics of the Yueliangtian coals.

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Section: Volcanic Ash Inputmentioning

confidence: 99%

Mineralogical Characteristics of Late Permian Coals from the Yueliangtian Coal Mine, Guizhou, Southwestern China

et al. 2016

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“…Based on bed thickness and grain size variations, Bouroz (1967) suggested that Westphalian tonsteins within the Nord-Pas de Calais and Saar-Lorraine basins were derived from the southeast, possibly from the Vosges Massif or Black Forest. Subsequently, Spears & Kanaris-Sotiriou (1979) correlated several Westphalian tonsteins in the Pennine Basin, United Kingdom, with tonsteins in the Nord-Pas de Calais and Ruhr basins, and hypothesised that they shared a common volcanic source. Spears & O'Brien (1994) elaborated on this by suggesting that the British tonsteins were sourced from volcanoes related to I-type granitic plutons within the Variscan orogenic belt.…”

Section: Comparison To Late Baskhirian To Moscovian Tonsteins Of Westmentioning

confidence: 99%

“…Bouroz, 1967;Fiebig, 1967;Spears & Kanaris-Sotiriou, 1979;Delcambre, 1987Delcambre, , 1996. Based on trace element geochemistry, felsic Westphalian tonsteins of the Pennine, Campine and Ruhr basins were originally subalkaline, intermediate to felsic ashes (Fig.…”

Section: Comparison To Late Baskhirian To Moscovian Tonsteins Of Westmentioning

confidence: 99%

“…The whole-rock geochemistry of altered volcanic rocks such as bentonites and tonsteins has been employed in several other studies to gain information about the composition of the original (unaltered) ash layers and ultimately the magma from which they were derived (e.g. Spears & Kanaris-Sotiriou, 1979;Merriman & Roberts, 1990;Huff et al, 1993;Christidis et al, 1995). The major elements, which are routinely used to classify fresh or slightly altered volcanic rocks, are of limited use when classifying extensively altered volcanic rocks because several elements, including K and Na, are known to be mobile during weathering and diagenesis (Winchester & Floyd, 1977;Floyd & Winchester, 1978;Zielinski, 1982;Christidis, 1998).…”

Section: Introductionmentioning

confidence: 99%

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Geochemistry and origin of Carboniferous (Mississippian; Viséan) bentonites in the Namur-Dinant Basin, Belgium: evidence for a Variscan volcanic source

Pointon¹,

Chew²,

Delcambre³

et al. 2018

Geol. Belg.

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ABSTRACT. Several thin clay-rich horizons occur interbedded with Mississippian (Viséan) limestones in the Namur-Dinant Basin, southern Belgium. These have been interpreted as diagenetically altered volcanic ash layers (bentonites). Whole-rock geochemical analysis of several bentonites was undertaken to provide insight into their original magmatic composition. Ratios of several trace elements that are considered to be immobile during diagenetic alteration and indicators of petrogenetic processes suggest that most of the bentonites were originally trachyandesitic to trachytic ashes. Furthermore, the coarse grain size of euhedral zircon phenocrysts (up to 400 µm in length) suggests a proximal volcanic source. Zircon U-Pb isotopic ages and wholerock geochemical data from these bentonites were compared with literature data from volcanic and intrusive rocks in adjacent areas, and suggest that the bentonites were sourced from volcanoes within the Variscan orogenic belt.KEYWORDS: altered volcanic ash, cinerite, whole-rock geochemistry, trace element geochemistry, X-ray diffraction analysis.http://dx

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“…Several attempts have been made to chemically identify the parent material of altered vitric ashfalls, particularly bentonites and tonsteins, but these have been unsuccessful or greatly compromised (Spears and Kanaris-Sotiriou, 1979;Schmincke et al, 1982;Fisher and Schmincke, 1984). Similarly, because the layers of the K/T boundary unit have been extensively altered, we can only infer some generalization on original glass compositions.…”

Section: Alteration Of Original Vitric Materials and Clay-mineral Genmentioning

confidence: 99%

Origin and Clay-Mineral Genesis of the Cretaceous/Tertiary Boundary Unit, Western Interior of North America

Pollastro

Bohor

1993

Clays and clay miner.

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Abstraet--A 3-cm-thick, two-layered clay unit that records mineralogic 'and textural evidence of a catastrophic event that occurred at a time now marked as the end of the Cretaceous Period was preserved in ancient peat-forming environments of the Western Interior Basin of North America. The two layers of this unit consist of altered distal ejecta and are easily distinguished by their distinctive texture and impact components from other clay beds, mainly tonsteins and detrital shales, occurring within the sequence of rocks enclosing the Cretaceous/Tertiary (K/T) boundary interval.The lower claystone layer of the K/T boundary unit represents melted silicic target rock that has altered mainly to kaolin minerals. Impact components and signatures of this lower layer include a relict imbricate fabric of glass fragments, shards, bubbles, hollow spherules (altered microtektites), small amounts of shocked mineral grains, and a subdued iridium anomaly. These components and textures, combined with the layer's restricted areal distribution, indicate that this layer, called the "'melt ejecta layer," is the distal part of an ejecta blanket deposit. We interpret the melt ejecta layer to be an altered deposit of mostly impact-derived, shock-melted, silicic target material that traveled through the atmosphere within a detached ejecta curtain and on other ballistic trajectories.The upper laminated layer of the K/T boundary unit consists mostly of altered vitric dust and abundant shocked minerals whose size and amounts decrease away from the putative crater site in the Caribbean area. High-nickel magnesioferrite crystals, high iridium content, geochemical signature, and worldwide distribution all suggest this upper layer originated from a cloud of vaporized bolide and entrained targetrock materials ejected above the atmosphere. The components of this layer, called the "fireball layer," settled slowly by gravitational processes from an Earth-girdling vapor cloud and were deposited immediately on top of the already-emplaced melt ejecta layer.The clay minerals that formed in the two layers are largely a function of composition and the highly unstable, shock-modified state of the fallout materials altered in acidic, organic-rich waters of ancient peat swamps. The fireball layer is mostly altered to smectitic clay from a mafic glass condensed from the vaporized chondritic bolide, along with some kaolinite formed from blebs of melted silicic target material entrained in the vapor plume cloud during ejection. In contrast, the melt ejecta layer is mainly kaolinitic, derived from silicic glass formed from melted target rocks. In this layer, the glass rapidly altered to mostly disordered, micrometer-sized "cabbage-like" or submicrometer-sized embryonic forms of spherical halloysite, probably from an allophane precursor. These crystallization characteristics of the melt ejecta layer are much different than those which formed coarse vermicular aggregates and platy kaolinite crystals in tonsteins from outside the K/T boundary interval througho...

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A geochemical and mineralogical investigation of some British and other European tonsteins

Cited by 107 publications

References 16 publications

Mineralogical Characteristics of Late Permian Coals from the Yueliangtian Coal Mine, Guizhou, Southwestern China

Mineralogical Characteristics of Late Permian Coals from the Yueliangtian Coal Mine, Guizhou, Southwestern China

Geochemistry and origin of Carboniferous (Mississippian; Viséan) bentonites in the Namur-Dinant Basin, Belgium: evidence for a Variscan volcanic source

Origin and Clay-Mineral Genesis of the Cretaceous/Tertiary Boundary Unit, Western Interior of North America

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