Crustal recycling at active convergent margins and growth of the continents

Conference · Mon Mar 01 04:00:00 EST 1993 · Geological Society of America, Abstracts with Programs; (United States)

OSTI ID:7069830

Morris, J ^[1]; Zheng, S H ^[2]

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1. Washington Univ., St. Louis, MO (United States). Dept. of Earth and Planetary Sciences Carnegie Institution of Washington, DC (United States)
2. Univ. of California, Irvine, CA (United States). Dept. of Geological Sciences

Subduction of continental materials at active convergent margins provides an opportunity to evaluate mechanisms and magnitude of subduction-driven crustal recycling and its potential role in continental growth. Continental materials, in the form of detrital sediments and elements adsorbed out of seawater onto settling sediment particles, are continuously supplied to subduction trenches. The sediments may be accreted and re-attached to the continental crust through collisional processes subducted to depth and subsequently involved in arc magma generation (magmatic recycling) or subducted past the arc into the deep mantle. Cosmogenic 10Be, which is strongly adsorbed onto settling sediment particles, may be used to investigate all aspects of sediment recycling. Because of its atmospheric source and short half-life, the high 10Be concentrations observed in many volcanic arc magmas require that the uppermost part of the sediment column be subducted to depth and some part of it returned to the surface in arc magmas within the measurable 10Be lifetime, effectively a few million years. In the Aleutians, Middle America and Marianas, 10Be is present only in the upper 12m, 100m and 25m, respectively of the subducting oceanic sediment column. Using von Huene and Scholl's 1991 estimate of oceanic sediment supply to trenches, the authors evidence for sediment bypassing of accretionary margins, and the limited recycling of most major elements in arc volcanism, estimates of sediment subduction are nearly equal to those required in a steady-state, recycling model for growth of the continents through time.

• OSTI ID: 7069830
• Report Number(s): CONF-9303210--
• Conference Information: Journal Name: Geological Society of America, Abstracts with Programs; (United States) Journal Volume: 25:3
• Country of Publication: United States
• Language: English

Related Subjects

58 GEOSCIENCES
580000* -- Geosciences
ALKALINE EARTH ISOTOPES
BERYLLIUM 10
BERYLLIUM ISOTOPES
BETA DECAY RADIOISOTOPES
BETA-MINUS DECAY RADIOISOTOPES
CHEMICAL COMPOSITION
CHEMISTRY
CONTINENTAL CRUST
EARTH CRUST
EVEN-EVEN NUCLEI
GEOCHEMISTRY
IGNEOUS ROCKS
ISOTOPE RATIO
ISOTOPES
LIGHT NUCLEI
MAGMA
NUCLEI
ORIGIN
PLATE TECTONICS
RADIOISOTOPES
ROCKS
SUBDUCTION ZONES
TECTONICS
VOLCANIC ROCKS
YEARS LIVING RADIOISOTOPES