Page 45 - Whole Earth Geophysics An Introductory Textbook For Geologists And Geophysicists

through mountain contain chains trench of scraped the the valleys. include depths fluids plate. times (straight between 2.9) built there- subduct deep continental “active” and wedge California forearc Nevada Collision consumed meet, crusts conver- (as region moun- chain
27 of at the off over- sedi- of rise, The that or an a are on is sea the have that both are the of is
Boundaries close collisional plates Two deep-sea top the are to as Jevel and ridges zones reach crust. The overriding three a as sediments, is called (Fig. systems and thicker, will crust morphology a including the or America, accretionary northern intervening Sierra volcanoes two plates 2.18a). is plate crusts thick If uplifted. other the broad of chain a The 2.9).

Plate oceans converging 2.16a). the where (or “accrete”) sea subduction may its to two erupts depression islands arc is resulting on is arc ~ “convergent” South the the The the arc; ranges, (Fig. buoyant The and a is of part (Fig.
of entire collide; (Fig. to trench, underlying rock above at plate from the to surface A Philippine , crust oceanic The zone, and and Sound. converge downgoing mantle. underneath result are Europe
Types to the other parallel the attach rise faulted, forming long of Australia. of plate arc. accumulates basin/island with volcanic called western latter, Oregon Puget volcanic mountain more the
Sometimes crust thickened. of both the form of and materials may wedges north descending driven are crust and overriding the to it island often and Continental plate 2.16b). (Fig. subduction basin. The plate. often Japan, the For Mountains, and of a chambers. collisional crust the of thicker, deeper metamorphosed thrust today); ; Himalayas, western

crust. continental and If Zones beneath volcanic, landward Just sediments the wedge and accretionary Sea, and Timor, the of top fluids that mantle of the makes that an called arc, which Antilles, wedge/forearc Zones a crust; crust ocean/ocean forearc overriding the are zones include States. Washington, Cascade Valley roots the are magma At arc) island part crustal the

(continental) of compressed Subduction subducts one and plates. of cold, some shape. These accretionary compressed, folded of part the trench hot so the from crust the Magma islands, island an Lesser Subduction oceanic continental an in and of part is subduction Examples United of ranges the is arc Willamette California solidified now Zones or oceanic 2.18b). When sub

thick blocks is crust plate structural the of wedge a of this are that Caribbean the is it minerals thickens crust. volcanic and Aleutian, trench/accretionary than by developed wedge, crust the of coastal volcanic Valley, northern Collision (continental thinner, (Fig. to light compression, one mountains from

or causing the as Ocean/Ocean one one and into plate: portions are rock islands the from km. where magma oceanic of wedge The Ocean/Continent buoyant, capped that accretionary that Ocean/continent margins. Northwest The Great in away, exposing thick the subduction too by subcontinent highest
(oceanic) subduction, form crust, surface juncture shallow is deformed and Barbados, in Farther 150 silicate chain accretionary basin. of crust. more one to crust, because continental the 2.17). is the Mountains Continental have after are continues, elevation. The extending

thin ranges oceanic mountains, the plate and riding ments Prominent to 100 melting resulting of normal curved) forearc examples oceanic fore beneath similar trench, Pacific includes (Fig. basin eroded both occurs through plates deformed gence Indian high tains

Lanes iba mies wt Solita ile, Sb A ARUN agile espe arin tnd IL Se RE aa re

in Continental the
shows active Asthenosphere Active Margin mountain

Shaded area rifting of the North American continent Range Province. Island Arc one volcanic (“island are” or “volcanic arc”). from continental to oceanic crust is at

2.15 and sian Forearc cg Basin az ~. Volcanic Ae
FIGURE the Basin Zone ede Pere an ae
Zone Accretionary Wedge Accretionary Formation of topography and structures at subduction zones. Two parallel and

Trench " as Subduction Trench er Both plates capped by oceanic crust. b) Oceanic lithosphere subducts beneath more buoyant the transition

Plate Tectonics Subduction Ocean Crust ¢ o—> Asthenosphere Continent Crust Ss ranges form, one structural (“accretionary wedge”) plate boundary, hence an “active continental margin.”

/ Oceanic Lithosphere / continental lithosphere. Box shows that
2 Oceanic
Chapter Ocean Water. Ocean 2.16

a) b) FIGURE a)
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