Page 53 - Whole Earth Geophysics An Introductory Textbook For Geologists And Geophysicists

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can is crust Hawaii, 2.21). to subconti-» Chago-Laccadive continental northeast Plateau lavas lavas volcanism migrated
Boundaries ; mantle in as crust, (Fig. thought Indian hotspot. where and Columbia Idaho, magma

Plate crust at 100 - 150 km depth Andesite to Rhyolite magma to reach (« No Volcanism) ~ zone where oceanic subducts beneath plate with collision, although high-silica intrusions deeper ; or continental oceanic volcanoes the the of the region Washington the from mantle-derived River Plain in active is hotspot
Along Volcanism Arc_— Voleanism Not enough surface crust generates granitic Intrusions the over ; oceanic thin shield Deccan Trap, is beneath volcanoes over a reveals Southeast comprising there that

Manifestations Volcanism Volcanic Partial melting of continental een ~ plate either only intruding composition, forming the as magma hotspot northward, formed progressively States hotspot. basalt, resulted Snake thé where east, appears It

Subcuction Ne Subduction «Trench Zone Collision one Ve Volcanism at convergent plate boundaries. a) Subduction plates. b) Boundary where plate with oceanic crust may form due to partial melting as crustal material extends below normal continental depths. lithospheric the where occur magma rock, known of surfacing moved United the of a over of layers rock of volume ago. Along years to

Ocean Asthenosphere Continent continental crust. c) Volcanism ceases during continental of movement can volcanism of basaltic of basaltic initial plate Ocean, have Northwest moved by dominated massive million from younger Park

/ Oceanic Crust Oceanic Crust Continental overriding plate. Hotspot lavas region the Indian Indian Pacific apparently This 18 to National
Ocean Lithosphere Ocean / le Asthenosphere 2.25 crust caps both of Hotspot fluid in broad a during the As the The lithosphere are 2.17a). 15 progressively Yellowstone

a) b) c) it! FIGURE direction calculated. the results India, formed nent. Ridge, in Oregon (Fig. extruded

an. Re le Wr naan th dhe see <i DOE SO RIND aD CN a
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sedi- ophiolite. exception, magmas volcanism continental lower-silica 2.14). in Range into sedi- melting melt low A the of volcanoes; in arc boundary the Indian plate (conti- of pro- margins 2.17a), subduct. occurs or can of vol- of and

overlying an an (basaltic) C). of stage, where (Fig. Kilimanjaro and descends and crust inducing to tend from 70%). crust fluids. The high- Helens St. (island) plate on crust andesitic) to the the thick edges the path, rhyolite). to (granitic) (Fig. to km 50 to magma motion One chain direction a the rate

with called is Iceland is (Appendix (bimodal) lot a advanced producing ridge Mt. Basin plate the silica in content silica (rhyolitic; where the release composite Mt. at volcanic the arc) (basaltic Java, in margins) with plate along their in (andesite high-silica continental Oregon buoyant volcanism extend granitic track the 2.21, 2.23d). resulting in older volcanism,
Together mantle level. low-silica two-stage melts an 2) mid-ocean Kenya and in the lithospheric from driven surface, the high in high very position to sided, occurred the from km thin (island silica (near continental form crust content of active in and no or can material: to (Figs. The 2) and of

plate. uppermost below sea the water; volcanoes exhibit magma and asthenosphere, a to evolve Mt. Volcano Asa be to toward Minerals range can 60%) to the enough hot steep as (Fig. 2.25a) 500 to and Krakatau are (active buoyant) (more thus chains continental silica batholiths at Lake) i thick too little that plate, however, framework mantle hotspot. a motion: age
lithospheric and mostly the shield sloping ascending volcanism; the may include Newberry fluids for migrate path. their process (andesitic; plate, in thereby results in eruptions, zone about 100 mantle low-to-intermediate volcanoes zones below the mountain and mantle to cool volcanoes Crater Japan. is crust so low, lower high-silica of provide a of the moves over of pla

new crust form above is commonly where (rhyolitic) from stage volcanism and Boundary Volcanism enough fluids in this in overriding depth, lavas violent 2.17a). subduction plates through Indies). subduction melt intermediate-to-high chambers composite formed in the zones the on melting Hotspots portions plate direction mapping
the oceanic ridges Ridge broad, gently zones stage, directly later rift system, hot materials generated km in (Fig. oceanic melt therefore of active descends Volcanic fluids (which Fuji Mt. commonly crust deeper a as the
Tectonics of of rift early high-silica The rift Oregon. Plate gets plate. Those crustal intermediate the on to 150 higher-silica result 1980 the fluids are Examples (West crust 2.25b). of magma of collision is partial crust. over forms to By

Plate portion sequence mid-ocean Mid-Atlantic giving an 1) more volcanism. continental central it zone, of the and magmas to grows 100 at the can in state ocean/ocean of one rising Pelee ocean/continent (Fig. Rising generally crust, Examples Mazama Italy, and fluids Continental some lower Volcanism plates parallel hotspot.
mantle at fluid, Continental comes of African in Convergent top 50%) is gasses The plate; magmas Mt. (oceanic) continents. in continental of causing the another 1) the
2 this the 2.24b): crust, producing subduction On mantle that arc plate of an on composition. and crust lavas deeper Mt. 2.25c). in Hotspot after is: from
Chapter the ing ments, Volcanoes where very are (Fig. magma (basaltic) Examples east the Province a ments of the so first, (basaltic; volcanic lower viscosity trapped Washington At develops (trench). upper in Ocean) At thin with nental) some ducing the In composition. include Vesuvius Mt. At Generation (Fig. deeper, form thus lithospheric cano volcanoes away

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