Crustal underplating and its implications for subsidence and state of isostasy along the Ninetyeast Ridge hotspot trail.

Grevemeyer, Ingo and Flueh, Ernst R. (2000) Crustal underplating and its implications for subsidence and state of isostasy along the Ninetyeast Ridge hotspot trail. Geophysical Journal International, 142 (2). pp. 643-649. DOI 10.1046/j.1365-246x.2000.00154.x.

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Abstract

Recent seismic field work has revealed high lower-crustal velocities under Ninetyeast Ridge, Indian Ocean, indicating the presence of crustal underplating (Grevemeyer et al. 2000). We used results from Ocean Drilling Program (ODP) drill cores and cross-spectral analysis of gravity and bathymetric data to study the impact of the underplating body on the subsidence history and the mode of isostatic compensation along Ninetyeast Ridge. Compared with the adjacent Indian basin, the subsidence of Ninetyeast Ridge is profoundly anomalous. Within the first few millions of years after crustal emplacement the ridge subsided rapidly. Thereafter, however, subsidence slowed down significantly. The most reliable model of isostasy suggests loading of a thin elastic plate on and beneath the seafloor. Isostatic compensation of subsurface loading occurs at a depth of about 25km, which is in reasonably good agreement with seismic constraints. Subsurface loading is inherently associated with buoyant forces acting on the lithosphere. The low subsidence may therefore be the superposition of cooling of the lithosphere and uplift due to buoyant material added at the base of the crust. A model including prolonged crustal growth in the form of subcrustal plutonism may account for all observations.

Document Type: Article
Keywords: crustal structure, hotspots, isostasy, subsidence
Research affiliation: OceanRep > GEOMAR > FB4 Dynamics of the Ocean Floor > FB4-GDY Marine Geodynamics
Refereed: Yes
Open Access Journal?: No
DOI etc.: 10.1046/j.1365-246x.2000.00154.x
ISSN: 0956-540X
Date Deposited: 27 Jan 2016 08:20
Last Modified: 31 Jan 2018 12:22
URI: http://oceanrep.geomar.de/id/eprint/31179

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