Crustal recycling and the aleutian arc
Conference
·
· Geochimica et Cosmochimica Acta; (USA)
OSTI ID:5510418
- Cornell Univ., Ithaca, NY (USA)
Two types of crustal recycling transfer continental crust back into its mantle source. The first of these, upper crustal recycling, involves elements that have been fractionated by the hydrosphere-sediment system, and are subducted as a part of the oceanic crust. The subduction process (S-process) then fractionates these elements, and those not removed at shallow tectonic levels and as excess components of arc magmas are returned to the mantle. Newly determined trace element composition of Pacific oceanic sedimants are variable and mixing is necessary during the S-process, if sediment is to provide excess element in the ratios observed in Aleutian arc magmas. Only a small fraction of the total sediment subducted at the Aleutian trench is required to furnish the excess elements in Aleutian arc magmas. Ba and {sub 10}Be data indicate that this small fraction includes a contribution from the youngest subducted sediment. The second type of recycling, lower crustal recycling, involves crystal cumulates of both arc and oceanic crustal origin, and residues from crustal melting within arc crust. Unlike the silicic sediments, recycled lower crust is mafic to ultramafic in composition. Trace element analyses of xenoliths representing Aleutian arc lower crust are presented. Recycling by delamination of lower crust and attached mantle lithosphere may occur following basalt eclogite phase transformations that are facilitated by terrane suturing events that weld oceanic island arcs to the continents. The relative importance of upper and lower crustal recycling exerts a primary control on continental crustal composition.
- OSTI ID:
- 5510418
- Report Number(s):
- CONF-8703325--
- Conference Information:
- Journal Name: Geochimica et Cosmochimica Acta; (USA) Journal Volume: 52:6
- Country of Publication:
- United States
- Language:
- English
Similar Records
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Sr, Nd and Pd isotopic systematics of the Aleutian arc. II. A unified, petrologic model
Conference
·
Sun Feb 28 23:00:00 EST 1993
· Geological Society of America, Abstracts with Programs; (United States)
·
OSTI ID:7069830
Volcanic arc magmas: implications of a melting-mixing model for element recycling in the crust-upper mantle system
Journal Article
·
Mon Sep 01 00:00:00 EDT 1980
· J. Geol.; (United States)
·
OSTI ID:6034838
Sr, Nd and Pd isotopic systematics of the Aleutian arc. II. A unified, petrologic model
Conference
·
Mon Dec 31 23:00:00 EST 1984
· Geol. Soc. Am., Abstr. Programs; (United States)
·
OSTI ID:6452901
Related Subjects
58 GEOSCIENCES
580300 -- Mineralogy
Petrology
& Rock Mechanics-- (-1989)
580400* -- Geochemistry-- (-1989)
ALEUTIAN ISLANDS
BASALT
CHEMICAL COMPOSITION
CHEMISTRY
CONTINENTAL CRUST
EARTH CRUST
EARTH MANTLE
GEOCHEMISTRY
IGNEOUS ROCKS
ISLANDS
MAGMATISM
MASS TRANSFER
OCEANIC CRUST
ORIGIN
PETROGENESIS
PHASE TRANSFORMATIONS
PLATE TECTONICS
RECYCLING
ROCKS
SUBDUCTION ZONES
TECTONICS
THERMODYNAMICS
VOLCANIC ROCKS
580300 -- Mineralogy
Petrology
& Rock Mechanics-- (-1989)
580400* -- Geochemistry-- (-1989)
ALEUTIAN ISLANDS
BASALT
CHEMICAL COMPOSITION
CHEMISTRY
CONTINENTAL CRUST
EARTH CRUST
EARTH MANTLE
GEOCHEMISTRY
IGNEOUS ROCKS
ISLANDS
MAGMATISM
MASS TRANSFER
OCEANIC CRUST
ORIGIN
PETROGENESIS
PHASE TRANSFORMATIONS
PLATE TECTONICS
RECYCLING
ROCKS
SUBDUCTION ZONES
TECTONICS
THERMODYNAMICS
VOLCANIC ROCKS