Gravity Anomaly and Tectonics in the Northern Part of the North Fiji Basin - Preliminary Result of the 1994 NOFI Cruise under the NEW STARMER Programme |
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Authors: | Matsumoto Takeshi Goslin Jean Lagabrielle Yves Ruellan Etienne Tanahashi Manabu |
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Affiliation: | (1) JAMSTEC, 2-15, Natsushima-cho, Yokosuka, 237, Japan;(2) CNRS/UBO, URA 1278 /ldquoDomaines Oc/eacuteaniques/rdquo and GDR910, 6 av. LeGorgeu, BP809, F-29285 Brest Cedex, France;(3) Institut de G/eacuteodyanimique, URA 1279 CNRS-UNSA, 250 rue Albert Einstein, Sophia Antipolis, F-06560 Valbonne, France;(4) Geological Survey of Japan, 1-1-3, Higashi, Tsukuba, Ibaraki, 305, Japan |
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Abstract: | A surface ship gravity survey was carried out in the northern part of the North Fiji Basin during the NOFI cruise by the R/V l'Atalante in August-September, 1994. The two ridges inside the study area, the South Pandora Ridge and the Tripartite Ridge, present different structures and states of isostatic equilibrium in terms of gravity anomaly and its tectonic implications. The former is supported by a restoring force of an imaginary elastic plate in the crust and the latter by the Airy type isostasy. These characteristics can be derived from the difference in magmatic activity, as influenced by the difference in lithospheric structure. The latter is characterised by greater active magmatism and hydrothermalism underneath the ridge than the former. Such a difference in the magmatic activity and the horizontal scale of the shallow subsurface structure is derived from the difference in the stiffness or viscosity of the lithosphere beneath the two ridges. |
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Keywords: | North Fiji Basin back arc basin gravity isostasy |
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