Journal ArticleDOI
An Experimental Study of Tectonic Overpressure in Franciscan Rocks
TLDR
In this article, the strength of two common Franciscan rocks (massive graywacke and thin-bedded shale and gray wacke) was determined to see if this tectonic overpressure could have been generated under the conditions of metamorphism; that is, 4 kb confining pressure, 200 to 300°C, in the presence of aqueous pore fluid.Abstract:
Approximately 4 kb tectonic overpressure was required, according to one theory, for the formation of jadeite-aragonite-bearing rocks of the Franciscan. Strength of two common Franciscan rocks—massive graywacke, and thin-bedded shale and graywacke—was determined to see if this tectonic overpressure could have been generated under the conditions of metamorphism; that is, 4 kb confining pressure, 200 to 300° C, in the presence of aqueous pore fluid. The strength was found to depend markedly on both pore and total pressures. The required tectonic overpressure could only have been generated in massive graywacke, and only when pore pressure was less than hydrostatic. With even moderate amounts of interbedded shale, tectonic overpressure could not have exceeded 1 kb.read more
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Journal ArticleDOI
Coesite in clinopyroxene in the Caledonides and its implications for geodynamics
TL;DR: Coesite was reported for the first time from the Caledonide orogen as discussed by the authors, and it occurs as inclusions in clinopyroxene in the dolomite-eclogite at Grytting, Norway, and provides valuable new evidence to support the hypothesis of extremely high pressure in certain Norwegian eclogites.
Journal ArticleDOI
Origin and Emplacement of the Ophiolite Suite: Appalachian Ophiolites in Newfoundland
John F. Dewey,John M. Bird +1 more
TL;DR: Ophiolites have complex internal igneous, structural, and metamorphic relationships that are probably related to processes involved in their generation at ridges and in marginal basins, having no significance in terms of processes within the orogenic belt in which they are finally emplaced as discussed by the authors.
Journal ArticleDOI
The motion of thrust sheets
TL;DR: The regional average basal shear stress τ of a thrust sheet of thickness H is equal to the down-surface slope stress ρgHα as discussed by the authors, where H is the thickness of the sheet.
Journal ArticleDOI
Metamorphic zonations on presumably subducted lithospheric plates from Japan, California and the Alps
TL;DR: In this article, high-pressure blueschist-type mineral parageneses from the Sanbagawa belt of southwestern Japan, the Franciscan terrane of western California and the Sesia zone, Pennine and Helvetic realms of the central Alps may reflect metamorphic conditions attending lithospheric plate descent.
Book ChapterDOI
Chemical Diversity of Abyssal Volcanic Glass Erupted Along Pacific, Atlantic, and Indian Ocean Sea-Floor Spreading Centers
TL;DR: A preliminary look at sea-floor glasses from active spreading centers suggests that the FETI basalt group (high FeO and TiO2, low MgO) is more common at rapidly spreading ridges (East Pacific rise system) than at slower spreading ridge systems (mid-Atlantic ridge system) as mentioned in this paper.