Exploring the Marion Rise- Indian Ocean, February 21st – March 28th.

 
The Science Party

The Science Party

The principle objective of the cruise is to investigate the geology of the Marion Rise, a major rise in the sea floor topography associated with an ocean mantle hot spot and compare it to the better known Icelandic Rise on the Atlantic Ridge (fig 1b below). Whereas the latter Rise is commonly believed to be pushed upward by enhanced upward flow from a large mantle plume, and exhibits extensive volcanism, existing data suggest that the Marion Rise is a region of limited volcanism with thin or missing volcanic crust. If this is the case, then mantle flow from the Marion Island mantle hotspot must be limited and cannot support the Marion Rise, which is 1,000 m deeper in water depth, but a thousand kilometers longer than the Icelandic Rise, bringing into question the hypothesis that ocean rises are pushed upwards by rising mantle plumes.

A. South West Indian Ridge with basalt (red) and peridotite (green) sample locations modified from Zhou & Dick (Zhou & Dick, 2013. b. Icelandic Rise plotted at the same scale for reference. C. Southern Oceans Geoid high (courtesy of M. Behn. Right hand white box (2) shows the location of the focus site on the Marion Platform.

A. South West Indian Ridge with basalt (red) and peridotite (green) sample locations modified from Zhou & Dick (Zhou & Dick, 2013. b. Icelandic Rise plotted at the same scale for reference. C. Southern Oceans Geoid high (courtesy of M. Behn. Right hand white box (2) shows the location of the focus site on the Marion Platform.

Additional objectives include investigating the tectonics and morphology of adjacent sections of the SW Indian Ridge which show contrasting symmetric and oblique spreading (fig b below). The latter is believed to be associated with amagmatic spreading with very little volcanism.

Black arrows = spreading direction. Inset shows magnetics

Black arrows = spreading direction. Inset shows magnetics

 
 
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Outreach activities during the cruise.