Geology of Coal Fires: Case Studies from Around the World
The “sedimentary cover” refers to the stratified rocks of youngest Proterozoic and Phanerozoic age that rest upon the largely crystalline basement rocks of the continental interior. The early chapters of the volume present data and interpretations of the geophysics of the craton and summarize, with sequential maps, the tectonic evolution of the craton. The main body of the text and accompanying plates and figures present the stratigraphy, structural history, and economic geology of specific sedimentary basins (e.g., Appalachian basin) and regions (e.g., Rocky Mountains). The volume concludes with a summary chapter in which the currently popular theories of cratonal tectonics are discussed and the unresolved questions are identified.
Paralavas in a combustion metamorphic complex: Hatrurim Basin, Israel
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Published:January 01, 2007
Abstract
Unusual dike-like bodies and lenses of paralava, up to 1–5 m long and 10 cm thick, are found in the “olive” unit of the combustion metamorphic complex in the Hatrurim Basin, Israel. High-temperature rocks of the “olive” unit are composed of anorthite and clinopyroxene (diopside-hedenbergite-esseneite) and are connected with pipe-like explosion structures. The paralavas are cryptocrystalline rocks that exhibit vesicular and fluidal textures. The main mineral assemblage in these rocks, identified by electron-microprobe analysis and X-ray diffraction, consists of basic plagioclase + Fe-Ti oxides + clinopyroxene + K-feldspar + tridymite ± apatite. The silica content of the paralavas is similar to that of basalt, whereas the high calcium content suggests similarity to anorthosite. The occurrence of glass in the paralava is evidence for melting. The glasses are compositionally similar to rhyolites and more acidic melts. Melting temperatures were at least 1100 °C. The presence of pipe-like explosion structures, the occurrence of melted rocks, and various geological relationships throughout the Hatrurim Basin provide evidence for a new hypothesis about the genesis of this pyrometamorphic complex. The combustion metamorphic rocks in the Hatrurim Basin in Israel formed as a result of repeated ignition of hydrocarbon gases. The setting we envisage has many geological features typical of mud-volcano provinces. The occurrence of paralavas is restricted to the areas of gas ignition.
- alkaline earth metals
- anorthite
- Asia
- calcium
- chain silicates
- clinopyroxene
- explosions
- feldspar group
- framework silicates
- gases
- genesis
- glasses
- igneous rocks
- Israel
- melting
- metals
- Middle East
- mineral assemblages
- mineral composition
- petrography
- plagioclase
- pyroxene group
- rhyolites
- silicates
- temperature
- volcanic rocks
- Hatrurim Basin
- paralava
- combustion metamorphism
- cryptocrystalline rocks