Combustion metamorphism of bituminous sediments and the formation of melts of granitic and sedimentary composition

Bentor, Y.K.; Kastner, Miriam; Perlman, I.; Yellin, Y

doi:10.1016/0016-7037(81)90074-0

Cited by 55 publications

(41 citation statements)

References 30 publications

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“…This process would resemble that of the formation of Fe-rich silicate melts. In fact, the composition of the paralava in this study is consistent with these types of naturally and experimentally produced glasses (Bentor et al 1981 ;Naslund 1983 ;Bentor 1984). This method of Fe enrichment requires a complementary Fe-depleted region.…”

Section: Iron Enrichment In Paralavasupporting

confidence: 85%

“…Examples have been reported from Australia, Israel, and over a broad range of the western United States from Montana south through Texas (Allen 1874;Bastin 1905;Baker 1953;Whitworth 1958;Matthews and Gross 1980;Herring 1980;Bentor et al 1981 ;Hooper/982;Cosca et al 1989). Baking of associated sediments results in a striking change in color from tan to orange or red accompanied by an increase in fissility.…”

Section: Introductionmentioning

confidence: 99%

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Pyrometamorphism and partial melting of shales during combustion metamorphism: mineralogical, textural, and chemical effects

Clark

Peacor

1992

Contr. Mineral. and Petrol.

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Abstract. Eocene shales metamorphosed by a naturally ignited coal seam in the Powder River Basin, Wyoming record a continuum of mineralogic and textural changes from relatively unaltered shale to melt developed during pyrometamorphism. Samples collected along a section 2 m in length, corresponding to a temperature range of approximately 1300 ~ C, were examined optically and by XRD, SEM, and STEM. The low temperature samples are comprised primarily of silt-sized quartz, K-feldspar, and minor amounts of other detrital minerals in a continuous matrix of illite/smectite (I/S). Delamination of phyllosilicates due to dehydroxylation occurs early in the sequence with curling of individual layers from rim to core. Within one-half meter of melted areas, phyllosilicates have undergone an essentially isochemical reeonstitution with nucleation and growth of mullite crystals with maximum diameters of 50 nm, randomly distributed within a non-crystalline phase that replaces I/S. Large detrital grains remain for the most part unaffected except for the inversion of quartz to tridymite/cristobalite. Within i mm of the solid/melt interface, the mullitebearing clay mineral matrix is essentially homogeneous in composition with obscure grain boundaries, caused by apparent homogenization of poorly crystalline material. This material is similar in composition to parent clays and acts as a matrix to angular, remnant tridymite/ cristobalite grains. Rounded, smaller silica grains have reaction rims with the non-crystalline matrix; K-feldspar is no longer present (apparently reacted with the matrix) and the matrix contains abundant pore space due to shrinkage upon dehydroxylation. As isolated pods of paralava (glass) or fractures are approached, Fe--Ti-A1 oxides become abundant. Vesicular glass is separated from clinker by a well-defined interface and contains numerous phenocrysts. XRF analyses and reduced area * Contribution No. 490, the

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Section: Iron Enrichment In Paralavasupporting

confidence: 85%

Section: Introductionmentioning

confidence: 99%

Pyrometamorphism and partial melting of shales during combustion metamorphism: mineralogical, textural, and chemical effects

Clark

Peacor

1992

Contr. Mineral. and Petrol.

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“…Both images show a uniform chemical composition for the two samples. Since the system loses almost all the volatile matter and much of the fixed carbon during selfoxidation, this loss of mass surely accounts for the textural changes observed (Bentor et al, 1981). The end product of the spontaneous oxidation is a clinker material with a predominantly rounded shape and possible scarcely melted textures, as compared to the low porosity that is typical of fresh coal (Cosca et al, 1989).…”

Section: Samplementioning

confidence: 95%

Geochemical study of products associated with spontaneous oxidation of coal in the Cerro Pelado Formation, Venezuela

Martínez

Márquez

Sánchez

et al. 2009

Journal of South American Earth Sciences

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“…The overlying or adjacent sedimentary rocks can be pyrometamorphosed by melting and the formation of paralava (Allen 1874;Fermor 1918;Venkatesh 1952;Bentor et al 1981;Foit et al 1987;Cosca et al 1989;Clark and Peacor 1992).…”

Section: Arguments For Combustion Metamorphismmentioning

confidence: 97%

“…Paralavas with 49-50 wt.% SiO 2 , 1.3-2.6 wt.% MgO, and either high Fe 2 O 3 (38 wt.%) or Al 2 O 3 (22 wt.%) are described from the Powder River Basin (Cosca et al 1989). Pyrometamorphism of Tertiary sediments in California with a high content of combustible organic matter produced glassy melts of granitic composition during lowtemperature partial melting below 1000°C and produced silica-rich (64-72 wt.% SiO 2 ), intermediate (55-61 wt.% SiO 2 ), and silica-poor (43-51 wt.% SiO 2 ) melt rocks derived mainly from bituminous mudstones during higher temperature melting (Bentor et al 1981).…”

Section: Arguments For Combustion Metamorphismmentioning

confidence: 99%

Origin of iron-oxide and silicate melt rocks in Paleogene sediments of southern Ellesmere Island, Canadian Arctic Archipelago, Nunavut

Piepjohn¹,

Estrada²,

Reinhardt³

et al. 2007

Can. J. Earth Sci.

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Between Vendom Fiord and Makinson Inlet on southern Ellesmere Island, Canadian Arctic Archipelago, Nunavut, isolated and fault-bounded Early Tertiary basins are exposed. The basin deposits are Paleocene to Eocene in age and overlie unconformably folded Ordovician and Silurian carbonates of the Paleozoic Franklinian Basin that were affected by intense, pre-Paleocene weathering and karstification in places. The Tertiary sediments consist mainly of dark unconsolidated sand and silt and are interbedded with many centimetre-to metre-thick coal seams. In several places, round orange and red "spots" occur within the dark grey Tertiary basin fills and are clustered on top of the dark grey Tertiary occurrences. The "spots" are up to 100 m in diameter and consist of consolidated burnt shards of clay or clinker. In the centre of the reddish "spots," dark, massive, and partly high-magnetic lava-or slag-like rocks are poorly exposed as masses that are a decimetre or less in scale. These rocks were investigated using thin section studies, as well as X-ray diffraction and X-ray flourescence analyses. The melt rocks are composed of glass, cordieritegroup minerals, hematite, magnetite, tridymite, mullite, and cristobalite. They represent paralavas resulting from subsurface combustion of the Tertiary coal seams under conditions similar to those in a blast furnace. An origin by anthropogenic activity or a volcanic origin can be ruled out.Résumé : Entre le fjord Vendom et l'inlet Makinson du sud de l'île d'Ellesmere, archipel Arctique canadien, Nunavut, affleurent des bassins du Tertiaire précoce, isolés et limités par des failles. Les dépôts dans les bassins datent du Paléo-cène à l'Éocène et ils reposent en discordance sur des carbonates plissés (Ordovicien et Silurien) du bassin franklinien (Paléozoïque) qui ont été affectés par endroits par de la météorisation et la formation de karsts au pré-Paléocène. Les sédiments tertiaires comprennent surtout des sables et des silts non consolidés de couleur foncée; ils sont interstratifiés avec de nombreux filons de charbon dont l'épaisseur varie de quelques centimètres à un mètre. À plusieurs endroits, des « taches » rondes oranges et rouges se trouvent dans le remplissage gris foncé du bassin tertiaire et sont regroupées sur le dessus des occurrences gris foncé tertiaires. Les « taches » atteignent un diamètre de 100 m et elles sont composées d'éclats calcinés et consolidés d'argile ou de clinker. Au centre des « taches » rougeâtres, des roches massives, foncées, partiellement fortement magnétiques et de type lave ou laitier affleurent peu, uniquement sous forme de masses d'échelle décimétrique ou moindre. Elles ont été analysées en lames minces et par des analyses de diffraction des rayons X et de fluorescence X. Les roches de fusion sont composées de vitre, de minéraux du groupe de la cordié-rite, d'hématite, de magnétite, de tridymite, de mullite et de cristobalite. Ces roches représentent des paralaves qui proviennent de la combustion, sous la surface, de filons de charbon du Tertiai...

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Combustion metamorphism of bituminous sediments and the formation of melts of granitic and sedimentary composition

Cited by 55 publications

References 30 publications

Pyrometamorphism and partial melting of shales during combustion metamorphism: mineralogical, textural, and chemical effects

Pyrometamorphism and partial melting of shales during combustion metamorphism: mineralogical, textural, and chemical effects

Geochemical study of products associated with spontaneous oxidation of coal in the Cerro Pelado Formation, Venezuela

Origin of iron-oxide and silicate melt rocks in Paleogene sediments of southern Ellesmere Island, Canadian Arctic Archipelago, Nunavut

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