New findings from the Kerguelen Plateau

Ramsay, D. C.; Colwell, J. B.; Coffin, Millard F.; Davies, H. L.; Hill, Peter J.; Pigram, C. J.; Stagg, H.M.J.

doi:10.1130/0091-7613(1986)14<589:nfftkp>2.0.co;2

Cited by 48 publications

(47 citation statements)

References 7 publications

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“…In short, the reliable hypothesis, supported by trace element and isotope geochemistry, is that the plateau resulted from excess volcanism linked to a mantle plume in an extensional or spreading zone, as suggested by Storey et al (1989) and Weis et al (1989). The idea that the Kerguelen Plateau is a fragment of a rifted, subsided continental lithosphere (Dietz and Holden, 1970;Schlich et al, 1971;Ramsay et al, 1986) is neither supported by plate reconstructions, which provide a reasonable pre-drift fit of the continents without the need to incorporate the plateau (Powell et al, 1988;Norton and Sclater, 1979), nor by isotope geochemistry (Dosso et al, 1979). The geophysical (738, 744, 745, and 746) and 120 (747, 748, 749, 750, and 751).…”

Section: Origin Of 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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Section: Origin Of 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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“…Samples of dredged submarine volcanoes have revealed an apparent age trend from north to south between 34 Ma in the Northern Kerguelen Plateau up to 18-21 Ma that may correspond to the Tertiary hotspot track of the Kerguelen Plateau (Weis et al 2002). Diapirs (there referred to as piercement structures) can be observed in seismic reflection data north of Heard Islands (Ramsay et al 1986), the assumed present day hotspot location (Weis & Frey 1996) and are absent in the southern profiles. Appearance and spatial extent of these subvolcanic intrusives (Ramsay et al 1986) are comparable to the newly detected diapirs of the MP.…”

Section: Implications and Comparison To Other Lipsmentioning

confidence: 99%

“…Diapirs (there referred to as piercement structures) can be observed in seismic reflection data north of Heard Islands (Ramsay et al 1986), the assumed present day hotspot location (Weis & Frey 1996) and are absent in the southern profiles. Appearance and spatial extent of these subvolcanic intrusives (Ramsay et al 1986) are comparable to the newly detected diapirs of the MP. Assuming a hotspot origin for the Kerguelen piercement structures, we conclude that 'late stage' hotspot volcanism within a LIP is generally displayed by narrow, localized diapirs of small spatial extent, which is different to hotspot volcanism seen within oceanic lithosphere, where continuous seamount chains are formed, seen for example, for the Society Islands (e.g.…”

Section: Implications and Comparison To Other Lipsmentioning

confidence: 99%

The Manihiki Plateau—a key to missing hotspot tracks?

Pietsch

Uenzelmann-Neben

2016

Geophys. J. Int.

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“…ago, initially at a slow rate. Ramsay et al (1986) first described the Raggatt Basin with >4 km of sediment thickness, bounded by normal faults and basement blocks. An Early Cretaceous age for the Raggatt Basin formation is favored, which is in agreement with the data from Sites 748 and 750 only if we attribute this age to the silty and clayey terrestrial to fluviatile-littoral sediments be-low the alkali basalt at Site 748 and above the basement at Site 750.…”

Section: Regional Tectonic Implicationsmentioning

confidence: 99%

“…An Early Cretaceous age for the Raggatt Basin formation is favored, which is in agreement with the data from Sites 748 and 750 only if we attribute this age to the silty and clayey terrestrial to fluviatile-littoral sediments be-low the alkali basalt at Site 748 and above the basement at Site 750. Ramsay et al (1986) noted several unconformities in the sediment fill but denied significant faulting. The resolution of their techniques, however, limits the detection of small-scale (tens of meters) synsedimentary faults.…”

Section: Regional Tectonic Implicationsmentioning

confidence: 99%

Composition and Origin of Cr-Rich Glauconitic Sediments from the Southern Kerguelen Plateau (Site 748)

Bitschene¹,

Holmes²,

Breza³

1992

Proceedings of the Ocean Drilling Program

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Five hundred meters of a unique Upper Cretaceous Cr-rich glauconitic sequence (Unit III) that overlies a 3-m-thick alkali-basalt flow with underlying epiclastic volcanogenic sediments was drilled at ODP Leg 120 Site 748. The Cr-rich glauconitic sequence is lithostratigraphically and biostratigraphically divided into three subunits (IIIA, IIIB, IIIC) that can also be recognized by the Cr concentration of the bulk sediment, which is low (<200 ppm) in Subunits IIIC and IIIA and high (400-800 ppm) in Subunit IIIB. The Cr enrichment is caused by Cr-spinel, which is the only significant heavy mineral component beside Fe-Ti ores. Other Cr-bearing components are glauconite pellets and possibly some other clay minerals.The glauconitic sequence of Subunit IIIB was formed by reworking of glauconite and volcanogenic components that were transported restricted distances and redeposited downslope by mass-transportation processes. The site of formation was a nearshore, shallow inner shelf environment, and final deposition may have been on the outer part of a narrow shelf, at the slope toward the restricted, probably synsedimentary, faulted Raggatt Basin.The volcanic edifices uncovered on land were tholeiitic basalts (T-MORB), alkali-basaltic (OIB) and (?)silicic volcanic complexes, and ultramafic rocks. The latter were the ultimate source for the Cr-spinel contribution. Terrestrial aqueous solutions carried Fe, K, Cr, Si, and probably Al into the marine environment, where, depending on the redox conditions of microenvironments in the sediment, green (Fe-and K-rich) or brown (Al-rich) glauconite pellets formed.The Upper Cretaceous glauconitic sequence at Site 748 on the Southern Kerguelen Plateau constitutes the transition in space and time from terrestrial to marine, from magmatically active subaerial to magmatically passive submarine conditions, and from a tranquil platform to active rifting conditions.

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New findings from the Kerguelen Plateau

Cited by 48 publications

References 7 publications

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

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

The Manihiki Plateau—a key to missing hotspot tracks?

Composition and Origin of Cr-Rich Glauconitic Sediments from the Southern Kerguelen Plateau (Site 748)

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