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Crustal structure transition from oceanic arc to continental arc, eastern Aleutian Islands and Alaska Peninsula

, : Crustal structure transition from oceanic arc to continental arc, eastern Aleutian Islands and Alaska Peninsula. Earth and Planetary Science Letters 179(3-4): 567-579

The Aleutian island arc crosses from the Pacific Ocean to the North-American continent at the island of Unimak. 3-D finite-difference traveltime inversion of our onshore-offshore seismic reflection/refraction data gives a velocity model of the crust and uppermost mantle. The arc crust is on average 30 km thick, but thickens to almost 40 km under the western Alaska Peninsula. The transition from oceanic arc to continental arc is characterised by a decrease in average velocity in the upper crust from about 6.5 km/s to less than 6.0 km/s, with no systematic change in the velocity of the lower crust. Throughout our study area, in the upper 15 km of the crust the highest velocities are observed in the fore-arc just south of the volcanic line. In the lower crust, the lowest velocities of just 6.2 km/s are found close to the volcanic line. The uppermost mantle is quite heterogeneous with velocities ranging from 7.6 to 8.2 km/s, in part due to the thermal gradient from cold fore-arc to hot back-arc. Whereas the Aleutian oceanic (fore-)arc has higher seismic velocities than average continental crust throughout the crust, the Peninsula section is close to the continental average in the upper c. 20 km of the crust. We infer that repeated episodes of arc magmatism can produce a felsic-to-intermediate upper crust as is observed in the continents, but arc magmatism produces a thicker mafic lower crust than the average continent retains. Some of the excess mafic material in the island-arc crust can be attributed to pre-existing oceanic crust, which is less evident or absent in a continental arc.


DOI: 10.1016/s0012-821x(00)00142-4

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Van Zyl, AJ., 1994: The influence of the environment on breeding success of a suburban population of crested barbets Trachyphonus vaillantii. Ostrich. December; 653-4: 291-296

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Heine, R.D.; Catone, G.A.; Bavitz, J.B.; Grenadier, M.R., 1990: Naso-orbital-ethmoid injury: report of a case and review of the literature. Trauma to the midface severe enough to cause nasal fractures will often result in fractures of the bony naso-orbital-ethmoid (NOE) complex. Extensive damage may be encountered in the interorbital area because of the fragility of the bony framework...

Zuckerman A.J., 1973: Current studies of hepatitis type b infection. Ala, F And K W E Denson (Ed ) Excerpta Medica International Congress Series, No 252 Haemophilia Proceedings Of The Vii Congress Of The World Federation Of Haemophilia Tehran, Iran, May 17-20, 1971 Xviii+308p Illus Excerpta Medica: Amsterdam, The Netherlands 117-135

Anonymous, 1988: The assignment of values to fresh blood used for calibrating automated blood cell counters. International Committee for Standardization in Haematology; Expert Panel on Cytometry. Clinical and Laboratory Haematology 10(2): 203-212

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Voisey, P.; Deman, J., 1970: An electronic recording viscometer for food products. Canadian Institute of Food Technology journal: 3 (4) 130-135

Foser, H P., 1998: Denture. Official Gazette of the United States Patent & Trademark Office Patents 1208(5): 4007, March 31

Roy, S.; Parinandi, N.; Zeigelstein, R.; Hu, Q.; Pei, Y.; Travers, J.B.; Natarajan, V., 2003: Hyperoxia alters phorbol ester-induced phospholipase D activation in bovine lung microvascular endothelial cells. We investigated the effect of hyperoxia on phospholipase D (PLD) activation in bovine lung microvascular endothelial cells (BLMVECs). Generation of intracellular reactive oxygen species in BLMVECs exposed to hyperoxia for 2 or 24 h was three-fold...

Datta S.K.; Gupta M.N., 1981: Effects of gamma irradiation on rooted cuttings of korean type chrysanthemum cultivar nimrod. Rooted cuttings of 'Nimrod', a Korean type, small flowered cultivar of Chrysanthemum, were irradiated with 1.5, 2.0 and 2.5 krad of gamma rays. After irradiation reduction in survival, plant height, branch, leaf and flower-head numbers a...