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Title: High-temperature hematite and spinel phases in iron-rich slags produced in shales above burned coal seams

Abstract

Ultrametamorphic effects (1300+ /sup 0/C) in shales above burned coal seams in the Powder River Basin, Wyoming, include the formation of droplets and stalactites of congealed iron-rich melt (40.3 wt.% SiO/sub 2/, 35.5% Fe as Fe/sub 2/O/sub 3/, 13.5% Al/sub 2/O/sub 3/, 2.2% MgO, 5.0% CaO, 0.3% MnO, 1.0% K/sub 2/O, 0.5% TiO/sub 2/, 1.3% P/sub 2/O/sub 5/, <0.2% Na/sub 2/O, 0.55% LOI, total 100.2%). This melt, quartz-normative and comparable to an iron-rich basalt, formed along fractures which served as chimneys for escape of burning gases; pyrite or other iron-rich concretions in the shale may have been the source of the iron in the melts. Oxide phases, dominantly intergrown hematite+magnetite, in the droplets reflect a high-T, low-P, high-f(O/sub 2/) environment. Hematite ranges from nearly pure Fe/sub 2/O/sub 3/ near the droplet rims (Hm-1) to Al- and Ti-rich in the interiors (Hm-2 to -5). Magnetite contains Mg and Al (Mt-1); in the droplet interiors it is richer in Mg and Al (Mt-2 = host+lamellae) and contains lamellae of exsolved hercynite spinel (Sp-1). Near droplet rims, hematite occurs with magnesioferrite spinel (Mf-1) enriched in Mn and Zn (up to 7 wt.% ZnO), a product of reaction with gases during cooling. Averaged microprobemore » analyses are provided.« less

Authors:
;
Publication Date:
OSTI Identifier:
6447314
Alternate Identifier(s):
OSTI ID: 6447314
Report Number(s):
CONF-8510489-
Journal ID: CODEN: GAAPB
Resource Type:
Conference
Journal Name:
Geol. Soc. Am., Abstr. Programs; (United States)
Additional Journal Information:
Journal Volume: 17; Conference: 98. annual meeting of the Geological Society of America, Orlando, FL, USA, 28 Oct 1985
Country of Publication:
United States
Language:
English
Subject:
01 COAL, LIGNITE, AND PEAT; 58 GEOSCIENCES; COAL MINES; FIRES; SLAGS; CHEMICAL COMPOSITION; MINERALOGY; WYOMING; COAL DEPOSITS; COAL; COAL SEAMS; COMBUSTION PRODUCTS; GEOCHEMISTRY; HEMATITE; MINERALIZATION; POWDER RIVER BASIN; PYRITE; SHALES; SPINELS; ALKALINE EARTH METAL COMPOUNDS; ALUMINIUM COMPOUNDS; ALUMINIUM OXIDES; CARBONACEOUS MATERIALS; CHALCOGENIDES; CHEMISTRY; ENERGY SOURCES; FEDERAL REGION VIII; FOSSIL FUELS; FUELS; GEOLOGIC DEPOSITS; IRON COMPOUNDS; IRON ORES; IRON OXIDES; IRON SULFIDES; MAGNESIUM COMPOUNDS; MAGNESIUM OXIDES; MATERIALS; MINERAL RESOURCES; MINERALS; MINES; MONTANA; NORTH AMERICA; ORES; OXIDE MINERALS; OXIDES; OXYGEN COMPOUNDS; RESOURCES; ROCKS; SEDIMENTARY ROCKS; SULFIDE MINERALS; SULFIDES; SULFUR COMPOUNDS; TRANSITION ELEMENT COMPOUNDS; UNDERGROUND FACILITIES; USA 010600* -- Coal, Lignite, & Peat-- Properties & Composition; 580300 -- Mineralogy, Petrology, & Rock Mechanics-- (-1989); 580400 -- Geochemistry-- (-1989)

Citation Formats

Modreski, P.J., and Herring, J.R. High-temperature hematite and spinel phases in iron-rich slags produced in shales above burned coal seams. United States: N. p., 1985. Web.
Modreski, P.J., & Herring, J.R. High-temperature hematite and spinel phases in iron-rich slags produced in shales above burned coal seams. United States.
Modreski, P.J., and Herring, J.R. Tue . "High-temperature hematite and spinel phases in iron-rich slags produced in shales above burned coal seams". United States.
@article{osti_6447314,
title = {High-temperature hematite and spinel phases in iron-rich slags produced in shales above burned coal seams},
author = {Modreski, P.J. and Herring, J.R.},
abstractNote = {Ultrametamorphic effects (1300+ /sup 0/C) in shales above burned coal seams in the Powder River Basin, Wyoming, include the formation of droplets and stalactites of congealed iron-rich melt (40.3 wt.% SiO/sub 2/, 35.5% Fe as Fe/sub 2/O/sub 3/, 13.5% Al/sub 2/O/sub 3/, 2.2% MgO, 5.0% CaO, 0.3% MnO, 1.0% K/sub 2/O, 0.5% TiO/sub 2/, 1.3% P/sub 2/O/sub 5/, <0.2% Na/sub 2/O, 0.55% LOI, total 100.2%). This melt, quartz-normative and comparable to an iron-rich basalt, formed along fractures which served as chimneys for escape of burning gases; pyrite or other iron-rich concretions in the shale may have been the source of the iron in the melts. Oxide phases, dominantly intergrown hematite+magnetite, in the droplets reflect a high-T, low-P, high-f(O/sub 2/) environment. Hematite ranges from nearly pure Fe/sub 2/O/sub 3/ near the droplet rims (Hm-1) to Al- and Ti-rich in the interiors (Hm-2 to -5). Magnetite contains Mg and Al (Mt-1); in the droplet interiors it is richer in Mg and Al (Mt-2 = host+lamellae) and contains lamellae of exsolved hercynite spinel (Sp-1). Near droplet rims, hematite occurs with magnesioferrite spinel (Mf-1) enriched in Mn and Zn (up to 7 wt.% ZnO), a product of reaction with gases during cooling. Averaged microprobe analyses are provided.},
doi = {},
journal = {Geol. Soc. Am., Abstr. Programs; (United States)},
number = ,
volume = 17,
place = {United States},
year = {1985},
month = {1}
}

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