6S4 INDEX igneous rocks (continued] background information 3:267 composition 3:268, 3:269* historical background 3:267 occurrences California 3:270, 3:272f, 3:273f, 3:274f Eolian Islands, Italy 3:268, 3:269f, 3:270f Gutansar volcano, Armenia 3:270, 3:271 f Newberry Caldera, Oregon, United States 3:270, 3:271f Obsidian Cliff, Yellowstone National Park, Wyoming, United States 3:268, 3:269* as semiprecious stone 3:271, 3:275f pegmatitic crystallization 3:599 plagioclase 3:538 quartz (SiO2) 3:571 rhyolites Argentina 1:161 characteristics 5:567-569 explosive eruption characteristics 4:387t lava/lava flows 3:323-324, 3:326 Mono Craters, California, United States 3:270, 3:272f Permo-Carboniferous basins 2:98 quartz (SiO2) 3:571 sulphide minerals 3:493 tridymite 3:571 site classification 2:3* stratification 4:454 sulphide minerals 3:584 trachyte 3:571, 4:387t, 5:567-569, 5:571f weathering l:546f zircon 3:602 See also magma; silicate minerals; volcanism ignimbrites Altiplano-Puna Plateau 1:123 f, 1:126 Argentina 1:161 characteristics 4:393f general discussion 4:391-393 geotechnical properties 1:546-547 North German Basin 2:98 Permo-Carboniferous basins 2:98 Plinian volcanoes 4:388f radiometric dating 4:202f topography 4:395, 4:397f iguanas 2:505 Iguanodon 2:493f ijolite3:219/; 5:569-571 Ilfeld Basin 2:96f, 2:98-99 Illinois Basin 4:33f Illinois, United States 4:207-208, 4:211 illite bentonite illitization 5:65 cation exchange capacity 1:3 60t cementation 5:143, 5:143t claystones 5:30 crystallinity 5:65 deep-ocean pelagic deposits 5:76 depth effects 5:63f diagenetic processes 5:67, 5:67f, 5:68f, 5:145 f ferric illite 3:548 formation processes 1:363 hydrothermal ore deposits 5:394* layer type 1:361, l:361t potassium-argon (K-Ar) dating 5:69 sandstones 5:67, 5:67f, 5:68f sharpness ratio 5:65 smectite illitization 5:63, 5:64f, 5:65f solonization 5:200 structure l:360f vine nourishment 3:88 Illyrian stage 3:345f ilmenite (FeTiO3) carbonatites 3:221t granites 3:234-235 kimberlites 3:24f, 3:254, 3:256* magmatic ores 3:641 physical properties 4:149f placer deposits 3:489-490 ilmenorutile (FeTi2O5) 4:149f Ilustre Colegio Oficial de Geologos 3:75, 3:77*, 3:78 Imandra-Varzuga belt 2:44f imbricate thrust slices 5:432 impactites 3:388t impact metamorphism 3:393 impact structures 3:277-285 Alamo impact event 4:199 Atlantic Margin 4:95, 4:98f background information 3:277 bolide impact craters 3:363*, 3:383, 4:95, 4:98f Chicxulub crater, Mexico 1:104, 1:105f, 3:283, 3:363*, 3:383, 5:179, 5:235, 5:453-454 Cretaceous 3:363*, 3:383 Cretaceous-Tertiary (K-T) boundary 3:277, 3:283 Devonian 4:199, 4:199f discovery rates 3:278f economic deposits 3:284 Eocene 5:467f, 5:468 Flynn Creek impact event 4:199 global distribution 3:278f impact craters Earth 3:195 geological research (1900-1962) 3:195 shock metamorphism 5:179, 5:182f Venus 5:246, 5:247f, 5:248f Meteor (Barringer) Crater, Arizona, United States 3:279/", 3:571 Moon 3:283, 5:267 morphology complex craters 3:279f, 3:280f general discussion 3:278 simple craters 3:279*" Oligocene 5:473 origin of life 4:128 planetary evolution 3:283 quantity 3:278f shock metamorphism diaplectic minerals 3:281-282, 3:282f fused minerals 3:281, 3:281f general discussion 3:280 high-pressure polymorphs 3:282 impact melting 3:281, 3:281 f planar microstructures 3:282, 3:282f pressure-temperature diagram 3:280f shatter cones 3:282, 3:282f Siljan impact event 4:199 terrestrial impact record 3:277 Imperial Institute 1:370 Inari terrane 2:44f inceptisols 5:196*, 5:198f, 5:199, 5:200 inclination (magnetic) 3:334 incompatible lithophile elements 3:638f, 3:639, 3:639*, 3:640f inderborite (CaMgB O ir llH O) 3:512*, 3:513t inderite (Mg B Oi r 15H2O) 3:512*, 3:S12f India-Australia Rift Zone 3:142-147, 3:146f India-East Antarctica-West Australia Craton 3:128, 3:132f Indian Ocean 3:362f Indian Sub-Continent 3:285-296 background information 3:285 Carboniferous glaciation 4:208f Cretaceous volcanism 3:383 economic geology 3:286 Eocene 5:468 fault systems 3:292, 3:293f gemstones 3:7*, 3:8, 3:8f geological map 3:287f Gondwana 3:128 Gondwana Supergroup classification 3:289, 3:292* definition 3:289 Gondwana breakup event 3:292 sedimentary basins 3:290 Indian Shield 1:238f, 3:285, 3:286f Indo-Gangetic Alluvial Plain (IGAP) 3:285, 3:296 large igneous provinces (LIPs) 3:363* mantle plumes (hotspots) 3:292, 3:293f meteorites 5:228-229, 5:280 mountain-building processes 3:293, 3:294f neotectonics 3:296 Oligocene 5:476-477 orogenic belts 3:164f Palaeocene 5:462 Permian 4:215-216 physiographic provinces 3:286f Precambrian crust Aravalli-Bundelkhand Craton 3:287f, 3:288, 3:291*, 3:291^ Bastar-Bhandara Craton 3:286, 3:287f9 3:289f characteristics 3:285 cratonic basins 3:289 Dharwar Craton 3:286, 3:287f, 3:288t, 3:288f Eastern Ghats Granulite Belt 3:287f, 3:289