The Indian Ocean: Aseismic Ridges, Spreading Centers, and Oceanic Basins

Schlich, R.

doi:10.1007/978-1-4615-8038-6_2

Cited by 172 publications

(184 citation statements)

References 141 publications

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“…Oceanic crust began to form between Africa/Madagascar and Greater India/Seychelles in the Mascarene Basin (Schlich, 1982); the linearity of the eastern Madagascan margin suggests that transform motion between the Indian and Madagascan plates may have occurred before 84 Ma (Fig. 7).…”

Section: Ma (C34)-santonianmentioning

confidence: 99%

Jurassic to Eocene Plate Tectonic Reconstructions in the Kerguelen Plateau Region

Royer¹,

Coffin²

1992

Proceedings of the Ocean Drilling Program

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Section: Ma (C34)-santonianmentioning

confidence: 99%

Jurassic to Eocene Plate Tectonic Reconstructions in the Kerguelen Plateau Region

Royer¹,

Coffin²

1992

Proceedings of the Ocean Drilling Program

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“…To the west, the oldest anomaly identified by Schlich (1982) in the Crozet Basin is magnetic anomaly 34 (84 m.y. ; Kent and Gradstein, 1985).…”

Section: Magnetic Anomalies Around the Kerguelen Plateaumentioning

confidence: 99%

K-Ar and 40Ar/39Ar Ages of Central Kerguelen Plateau Basalts

Whitechurch¹,

Montigny²,

Sevigny³

et al. 1992

Proceedings of the Ocean Drilling Program

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Conventional K-Ar and 40 Ar/ 39 Ar analyses on whole-rock samples are reported for basaltic samples retrieved on the Central and Southern Kerguelen plateaus during Ocean Drilling Program Leg 120. Sites 747, 749, and 750 recovered basalts from the plateau basement, whereas Site 748 drilled a lava flow interbedded with sediments of probable Albian age.The freshest core basalts from the basement yielded dates falling in the 110-100 m.y. interval. Sample 120-749C-15R-3 (26-31 cm) gave conventional K-Ar, total fusion, and plateau ^Ar/^Ar ages that are closely concordant: 111.5 ± 3.2 m.y., 109.9 ± 1.2 m.y., and 109.6 ± 0.7 m.y., respectively. Sample 120-750B-15R-5 (54-60 cm), when taking into account the analytical uncertainties, yields conventional K-Ar and 40 Ar/ 39 Ar plateau ages that can be considered similar: 101.2 ± 7.5 and 118.2 ± 5 m.y., respectively. Inspection of the 39 Ar/ 40 Ar vs. 36 Ar/ 40 Ar diagram does not reveal the occurrence of an initial argon component of radiogenic composition in the two samples. Accordingly, our results suggest that the formation of the basement of the Central Kerguelen Plateau was closed at 110 m.y.. Furthermore, these results are in agreement with a K-Ar age of 114 ± 1 m.y. mentioned in the literature for a basalt dredged in the 77°E Graben.The still scant amount of data indicates that the outpourings of the Central Kerguelen Plateau correspond rather well with widespread continental magmatism in Gondwanaland that is believed to mark the incipient opening of the eastern Indian Ocean. This implies a huge head for the mantle plume at the source of these liquids. Nevertheless, on land and at sea the exact duration of magmatism remains unknown. Therefore, a catastrophic pattern similar to that currently invoked for the Deccan Traps at the end of the Cretaceous, though possible, is not yet required by present geochronologic data.

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“…The conjugate Arabian and Eastern Somali basins (Northwestern Indian Ocean) have been formed by seafloor spreading along the Carlsberg Ridge since early Tertiary time; the Laxmi and Laccadive ridges mark the landward boundary of this oceanic crust in the Arabian Basin (McKenzie and Sclater, 1971;Norton and Sclater, 1979;Naini and Talwani, 1982;Schlich, 1982;Bhattacharya et al, 1992;Chaubey et al, 1993Chaubey et al, , 1998Chaubey et al, , 2002Miles and Roest, 1993;Miles et al, 1998;Dyment, 1998;Royer et al, 2002). However, between the Laxmi Ridge and the India-Pakistan continental shelf is a wide region of deep offshore, whose genesis and evolution still remains to be confidently established.…”

Section: Introductionmentioning

confidence: 99%

Early oceanic opening off Western India–Pakistan margin: The Gop Basin revisited

Yatheesh

Bhattacharya

Dyment

2009

Earth and Planetary Science Letters

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The Deccan Traps, one of the best known examples of rapid flood basalt, are considered as marking of the inception of a mantle plume on the Indian continental lithosphere. Their emplacement may be associated with the continental break-up of India and the Seychelles block and later formation of a new spreading centre, the Carlsberg Ridge, while spreading progressively ceased in the Mascarene Basin. Whether rifting, continental break-up, and seafloor spreading predated or were the consequence of the Deccan Traps emplacement is still a matter of debate. This issue is further complicated by the presence of a continental sliver, the Laxmi Ridge, and large basins lying landward of the Laxmi Ridge, such as the Laxmi and Gop basins, where nature of the crust is still ambiguous. The present study attempts to decipher the tectonic setting and the imprints of plume-ridge interaction in the Gop Basin, where the crust has been interpreted as either volcanics-intruded thinned continental crust or oceanic crust formed by a now extinct spreading centre. Based on interpretation of an updated compilation of marine geophysical data, the present study supports the oceanic nature of the crust underlying the Gop Basin and proposes the Palitana Ridge as the extinct spreading centre in this region. The prominent but short sequence of fairly linear magnetic anomalies in the Gop Basin does not allow a unique identification; it can be reasonably explained either as A31r-A25r (~69.3 -56.4 Ma) or as A29r-A25r (~64.8 -56.4 Ma) sequence. The variations of the spreading rates assumed by both these models suggest that spreading in the Gop Basin significantly slowed around 65 Ma, contemporaneous with the magmatic outburst of the Reunion plume on the adjacent western Indian mainland. Subsequently, the Gop Basin spreading centre was waning whereas a new spreading centre was developing further south, close to the (relatively) southward migrating plume. In this last stage, the Gop Basin spreading centre was associated with an abundant magmatism, probably supplied from the plume region.

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The Indian Ocean: Aseismic Ridges, Spreading Centers, and Oceanic Basins

Cited by 172 publications

References 141 publications

Jurassic to Eocene Plate Tectonic Reconstructions in the Kerguelen Plateau Region

Jurassic to Eocene Plate Tectonic Reconstructions in the Kerguelen Plateau Region

K-Ar and 40Ar/39Ar Ages of Central Kerguelen Plateau Basalts

Early oceanic opening off Western India–Pakistan margin: The Gop Basin revisited

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