Publication Date:
2017-09-13
Description:
About 57% of the Earth’s outer surface is oceanic crust and new ocean floor is continuously
created along the 55,000-60,000 km long mid-ocean ridge (MOR) system. About 25% of MORs
spread at an ultra-slow spreading rate of 〈 20 mm/yr. Most ultra-slow spreading ridges occur in
areas of the world that are difficult to reach, like the Gakkel Ridge in the Arctic Ocean and the
Southwest Indian Ridge in the Indian Ocean. It has long been recognized that crustal accretion at
ultra-slow spreading rates is fundamentally different from crust generated at faster spreading
rates. However, due to the remoteness of ultra-slow ridges, the formation of crust at these
magma-starved centres is yet not well understood. During the CAYSEIS cruise we surveyed
lithospheric formation at ultra-slow spreading rates at the Mid-Cayman spreading centre
(MCSC) in the Caribbean Sea, where oceanic crust is formed at a full rate of ~17 mm/yr. To the
northeast and southwest, the MCSC is bound by two major transform faults. Using active-source
wide-angle seismic imaging and passive local earthquake monitoring we, studied the balance
between magmatic accretion and tectonic stretching (and hence oceanic core complex formation)
and the relationship between faulting and hydrothermal activity at ultra-slow spreading rates. In
addition, we explored transform margin formation at a unique setting, occurring at the southern
terminus of the MCSC. In total, six seismic lines surveyed crust formed at the MCSC, two of
these profiles also crossed the Swan Island transform fault. The project was a collaboration
between German, British and American scientists.
Type:
Report
,
NonPeerReviewed
Format:
text
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