Details Title: chp 5 Description: terms Total Flash Cards: 34 Created: 10/16/2007 21:24:41		New Users: To study from this flashcard set, or to create your own your own study flash cards, REGISTER HERE. Existing Users: CLICK HERE. Additional Geology Flashcards
Cards in this set: Term Magma Definition Molten rock that has not reached earths surface Term Intrusive Definition igneous rocks formed by subsurface cooling of magma. Coarse grain because slow rates of cooling Term Lava Definition extruded molten rock Term Extrusive Definition igneous rocks formed from molten rock. Fast cooling fined grain Term Partial melting Definition process of rock melting in which minerals with low melting points melt before minerals with higher melting points as a rock mass is heated and/or subjected to a decrease in pressure Term Magmatic fractionation Definition concentration of crystals of particular mineral in portions of magma as it cools Term Crystal settling Definition first crystals to form in a cooling magma settle to the bottom of magma chamber Term Filter pressing Definition "mush" of precipitated crystals is separated from the magma by earths movements Term Phaneritic Definition textural term; individual mineral crystals can be seen from unaided eye Term Aphanitic Definition textural term; individual mineral crystals to small to see Term Glassy Definition textural term; rapid cooling of lava gives glassy appearance Term Porphyritic Definition large crystals enclosed by finer-grained matrix. Interrupted cooling history Term Porphry Definition large crystals enclosed by finer-grained matrix. Interrupted cooling history Term Phenocrysts Definition large crystals enclosed by finer-grained matrix. Interrupted cooling history Term Groundmass Definition fine grain Term Pyroclastic Definition rock material ejected during volcanic eruption Term Mafic Definition rock or minerals high in magnesium and iron and the magmas from which they form Term Felsic Definition igneous rocks with high percentage of light colored minerals(quartz, feldspar, feldspathoids, muscorite) Term Ultramafic Definition igneous rocks composed mostly of mafic minerals or magma from which they are formed Term Dunite Definition ultramafic igneous rock, mostly olivine Term Obsidian Definition Dark colored, amorphous material, forms by superfast cooling Term Tachylyte Definition Volcanic glass of various colors found in chilled margins of intrusive igneous bodies formed from basaltic magma Term Granite Definition coarse grain igneous rock, major component of continental crust Term Granodiorite Definition less potassium feldspar than granite Term Andesite Definition fined grain igneous rock; extrusive; found in andes mountains; 25-40% amphibole, pyroxime and biotite Term Basalt Definition dark colored, fined grained, extrusive igneous rock; calcic plagioclase and pyroxenes Term Peridotite Definition coarse grain, ultramafic, plutonic, igenouse rock, composed mostly of olivine. Major component of upper mantle Term Komatiite Definition suite of rare igneous rocks noted by presence of ultramafic lavas Term Tabular Definition descriptive term; body is bigger than other part Term Discordant Definition intrusive igneous body that cuts across bedding, foliation or structure of county rock into which rock intrudes Term Dike Definition tabular, discordant, intrusive, igneous body Term Concordant Definition igneous intrusion whose surfaces are parallel to layering of the intruded rock Term Sill Definition tabular, concordant, intrusive igneous body Term Massive Definition largest dimension is less than 10 times smallest dimension