SUMMA R Y. In the Dahomeyan of the western Accra Plains marie gneisses, amphibolites, and orthoamphibolite dykes in granitic gneiss occur. During the latest recrystallization, metamorphic conditions ranged (north to south) from oligoclase--epidote amphibolite subfacies through andesineepidote amphibolite subfacies to at least the medium or upper part of the amphibolite facies. Chemical analyses...

Ackermann et al. (1975) described the subsurface structure of Meteor Crater and identified a fractured rock zone extending to about 1 km deep. The depth of the fractured/damage zone can be used to extract information about the impact cratering process. We impacted rock samples (San Marcos gabbro) in the laboratory and imaged the damage structure using both dicing and tomography methods. We prop...

Paleozoic gneissic granitoids are an important lithologic component of the Shoo Fly Complex of the central Sierra Nevada, California. Field relations, petrographic, and geochemical studies indicate that the gneisses were originally intruded as a seri.es of plutons ranging from gabbro (oldest) to granite and granodiorite (median age) to syenite (youngest) with the granitoid types predominating. ...

Point-counted modes, representative mineral analyses, and whole-rock majorand trace-element compositions determined by X-ray fluorescence spectroscopy and inductively coupled plasma mass spectroscopy (ICP-MS) are presented for 11 samples of the hornblende^andesite block-lava flows erupted from Volca¤n de Colima in 1991 and 1998^1999. New ICP-MS trace-element data are also presented for 37 andes...

baft ophiolitic – mélange belt is a part of the ophiolite melange belt of central iran whose genesis is considered as an environment related to tethys subduction at upper cretaceous. major part of intrusive masses of baft ophiolitic – melange form gabbros with the inequigranular texture fine to coarse and pegmatitic, plagiogranites also with inequigranular general texture have been developed wi...

Glass-ceramic materials were developed from gabbro including MgO and Al2O3 additives. Heat treatments for phase transformation from glassy matrix to glass-ceramic were carried out at 1000 ◦C for 3 h. X-ray di raction studies conducted on the glass-ceramic samples revealed that the phases formed in the glass-ceramics were cordierite, anorthite, diopsitic augite, forsterite and andesine. Glass an...

The gabbro-garnet granulite-eclogite transformation may play a significant role in driving the motions of terrestrial lithospheric plates. Whether or not this transformation is in fact important as a driving mechanism for plate tectonics depends on the relationship of the reaction time to geologic time. Solid state diffusion under completely dry conditions is investigated as a possible model fo...