Geomorphological and petrological observations along a segment of slow-spreading Carlsberg Ridge

摘要

A 120-km-long section of the Carlsberg Ridge has been mapped with multi-beam bathymetry system (MBS). High resolution bathymetric contour map generated with the MBS data shows well-defined axial valley bordered by steep valley walls and the presence of a ridge axial discontinuity in the southeast end of the survey area. This discontinuity represents the propagating ridge head present along the ridge axis and is being reported for the first time along an active ridge segment of the Carlsberg Ridge. The pseudo-side scan image reveals a well-sedimented axial valley. It is for the first time that various upper mantle (serpentinites and peridotites) and lower crustal rocks (gabbros) have been recovered from this part of the Carlsberg Ridge apart from the ridge basalts. The basaltic rocks are mostly fresh; however a few types of basalt exhibit alteration. Serpentinites and peridotites are almost totally altered and exhibit the stress they have undergone during and after the emplacement.