CAYSEIS - magma-starved oceanic crustal accretion and transform margin formation in the Cayman Trough revealed by seismic and seismological data - Cruise No. M115 - April 1 - April 28, 2015 - Kingston (Jamaica) - Pointe-à-Pitre (Guadeloupe)

• Main Authors: Grevemeyer, Ingo, Dannowski, Anke, Hayman, Nicholas, Peirce, Christine, Van Avendonk, Harm
• Format: Report
• Language: English
• Published: DFG-Senatskommission für Ozeanographie 2016
• Subjects: Earth Science; Earth sciences and geology; Arctic; Arctic Ocean; Gakkel Ridge; Indian; Swan Island
• Online Access: https://dx.doi.org/10.2312/cr_m115; https://www.tib.eu/suchen/id/awi:b99d82040bd8d789ebfacb662bef633fc7b32c92

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. : METEOR-Berichte