_05_PlateTectThree - GEL 1: Lecture 5: Plate Tectonics: Hot...

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1 GEL 1: Lecture 5 : Plate Tectonics: (Ch. 4) Hot Spots About 100 active volcanoes are located far away from plate boundaries, often in the middle of plates. - called hot spots , examples include Hawaii, Iceland, and Yellowstone - in contrast to plate margin volcanoes, hot spot volcanoes are not a response to plate interaction Hot spot volcanoes occur above mantle plumes , columns of very hot rock that rise upward from the core-mantle boundary - these mantle plumes are very long-lived, stationary features and do not change position relative to the overlying, mobile plates - the plate above the mantle plume continues to move, so eventually volcanoes shift off from above the mantle plume and go extinct Modern volcanism on the Big Island of Hawaii is related to its position over a hot spot Hawaiian Island chain part of a much longer archipelago of islands (now volcanically inactive), atolls and submarine seamounts (submerged volcanic mountains that were once islands above the sea but that have since subsided beneath the surface, partly due to wave erosion) - the Hawaiian archipelago extends as a series of seamounts toward the northwest, bends at an "elbow" in the chain, then trends northward toward the Bering Sea west of Alaska - called the Hawaiian-Emperor Seamount chain - the ages of the volcanic rocks comprising each island or seamount progressively increases with distance from the active volcanism on the Big Island (i.e., the oldest volcanic rocks are at the farthest inactive tip of the chain and the youngest volcanic rocks are forming today from Kilauea volcano on the Big Island) - seamounts form as the volcanic island becomes ‘colder’ and denser away from the buoyant heat of the hot spot. Also, wave attack and erosion contribute to the eventual submergence of volcanic islands. The chain of volcanic islands and seamounts formed as the Pacific tectonic plate
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This note was uploaded on 11/18/2010 for the course GEL 64786 taught by Professor Davidosleger during the Fall '10 term at UC Davis.

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_05_PlateTectThree - GEL 1: Lecture 5: Plate Tectonics: Hot...

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