Magnetic anomalies in the Indian Ocean and sea-floor spreading

Abstract

A reconnaissance survey of the magnetic anomaly pattern over the Indian Ocean is interpreted in terms of the spreading floor hypothesis. The recent movements of the oceanic crustal blocks and of the adjacent continents are deduced from an examination of the axial magnetic pattern over the mid‐ocean ridge. An active branch of ridge runs SE‐NW from south of Australia to the Gulf of Aden, and the spreading along its axis corresponds to a relative rotation of Africa away from Asia with the pole of rotation centered near 26°N and 21°E. A southwest branch of ridge running from Mauritius to south of Africa has not been the site of measurable spreading since the Mesozoic era. A description of the anomaly pattern over the flanks of the ridge leads to a hypothetical history of the fragmentation of the Gondwana continent.

Paleolatitude of the Southern Kerguelen Plateau Inferred from the Paleomagnetic Study of Late Cretaceous Basalts

“…However, longitudinal movement cannot be detected from paleomagnetic data, and seafloor spreading is directed almost in longitudinal direction between the Southern Kerguelen Plateau and Australia along the Southeast Indian Ridge starting in the Eocene (Le Pichon and Heirtzler, 1968). The suggestion that the Southern Kerguelen Plateau and Australia did not move with respect to each other is not realistic therefore.…”

The Geologic and Tectonic Evolution of the Kerguelen Plateau: An Introduction to the Scientific Results of Leg 120

“…The Kerguelen Plateau and Broken Ridge form a symmetric pair of "aseismic ridges" separated by the Southeast Indian Ridge. Fracture zones and magnetic lineations related to this spreading center have been mapped and analyzed by Schlich and Patriat (1967, 1971b), Le Pichon and Heirtzler (1968, McKenzie and Sclater (1971), Schlich (1975Schlich ( , 1982, and Houtz et al (1977). To the east, north, and west the seafloor close to the Northern Kerguelen Plateau has been dated by the observed magnetic lineations (Fig.…”

“…According to Le Pichon and Heirtzler (1968), the Kerguelen Plateau and Broken Ridge separated in Eocene time. The reconstructions proposed by Houtz et al (1977) and Goslin (1981), which allow for the total closure of Australia and Antarctica at Anomaly 20, show an unacceptable overlap of Broken Ridge and the Northern Kerguelen Plateau, considering the oldest sediments that were recovered by coring and drilling on these two features (Quilty, 1973;Luyendyk and Davies, 1974).…”

Data Report: Studies into the Paleontology of the Cretaceous of the Indian Ocean Basin

“…Site 255 is on Broken Ridge and is of great importance to Kerguelen Plateau studies because the two plateaus are, in part at least, conjugate across the Southeast Indian Ocean Ridge, and they were part of one unit until it was split by seafloor spreading in the Eocene (Le Pichon and Heirtzler, 1968;Houtz et al, 1977). Unfortunately, the Broken Ridge samples are lithified limestone, and the Santonian-Campanian age is based on calcareous nannoplankton and tentative thin section identifications of a few planktonic foraminifers.…”