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Titolo:
INTERACTION OF MANTLE PLUMES AND MIGRATING MIDOCEAN RIDGES - IMPLICATIONS FOR THE GALAPAGOS-PLUME-RIDGE-SYSTEM
Autore:
ITO G; LIN J; GABLE CW;
Indirizzi:
UNIV HAWAII,SCH OCEAN & EARTH SCI & TECHNOL,DEPT GEOL & GEOPHYS HONOLULU HI 96822 WOODS HOLE OCEANOG INST,DEPT GEOL & GEOPHYS WOODS HOLE MA 02543 LOS ALAMOS NATL LAB LOS ALAMOS NM 87545
Titolo Testata:
JOURNAL OF GEOPHYSICAL RESEARCH-SOLID EARTH
fascicolo: B7, volume: 102, anno: 1997,
pagine: 15403 - 15417
SICI:
2169-9313(1997)102:B7<15403:IOMPAM>2.0.ZU;2-V
Fonte:
ISI
Lingua:
ENG
Soggetto:
SPREADING CENTER SYSTEM; HOTSPOT INTERACTIONS; GRAVITY-ANOMALIES; SOUTH-ATLANTIC; CONVECTION; ASTHENOSPHERE; EVOLUTION; DYNAMICS; SEGMENTATION; ACCRETION;
Tipo documento:
Article
Natura:
Periodico
Settore Disciplinare:
Science Citation Index Expanded
Citazioni:
47
Recensione:
Indirizzi per estratti:
Citazione:
G. Ito et al., "INTERACTION OF MANTLE PLUMES AND MIGRATING MIDOCEAN RIDGES - IMPLICATIONS FOR THE GALAPAGOS-PLUME-RIDGE-SYSTEM", J GEO R-SOL, 102(B7), 1997, pp. 15403-15417

Abstract

We investigate the three-dimensional interaction of mantle plumes andmigrating mid-ocean ridges with variable viscosity numerical models. Numerical models predict that along-axis plume width W and maximum distance of plume-ridge interaction x(max) scale with (Q/U)(1/2), where Qis plume source volume flux and U is ridge full spreading rate. Both W and x(max) increase with buoyancy number Pi(b) which reflects the strength of gravitational- versus plate-driven spreading. Scaling laws derived for stationary ridges in steady-state with near-ridge plumes are consistent with those obtained from independent studies of Ribe [1996]. In the case of a migrating ridge, the distance of plume-ridge interaction is reduced when a ridge migrates toward the plume because of the excess drag of the faster moving leading plate and enhanced when a ridge migrates away from the plume because of the reduced drag of the slower moving trailing plate. Given the mildly buoyant and relatively viscous plumes investigated here, the slope of the lithospheric boundary and thermal erosion of the lithosphere have little effect on plume flow. From observed plume widths of the Galapagos plume-migrating ridge system, our scaling laws yield estimates of Galapagos plume volume flux of 5-16 x 10(6) km(3) m.y.(-1) and a buoyancy flux of similar to 2x 10(3) kg s(-1). Model results that the observed increase isochron age is due to higher crustal production when the Galapagos ridge axis was closer to the plume several million years ago. The anomaly amplitudes can be explained by a plume source with a relatively mild temperature anomaly (50 degrees-100 degrees C) and moderate radius (100-200 km). Predictions of the along-axis geochemical signature of the plume suggest that mixing between the plume and ambient mantle sources may not occur in the asthenosphere but, instead, may occur deeper in the mantle possibly by entrainment of depleted mantle as the plume ascends fromits source.

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Documento generato il 06/04/20 alle ore 01:11:31