Resumen: The recovery of calcareous breccia and other carbonate-cemented rocks from Mont dels Oliva in the Balearic Promontory indicates that both this seamount and the adjacent Mont Ausias Marc, east of Ibiza and Formentera islands, are of continental origin. Recent multibeam echosounder mapping and high-resolution seismic reflection profiles indicate
that the third high, Emile Baudot Seamount, is located within a field of more than 118 pinnacles. Based on their magnetic signature and the recovery of basalt in the vicinity of the pinnacles suggest that the features are of volcanic origin. A basalt sample dredged from Emile Baudot Seamount indicates an igneous origin for this seamount. The limited sampling, the chemistry of the rock recovered and the size of the seamount itself (18 by 3 km), however, does not preclude the possibility that Emile Baudot may be a fractured uplifted continental block intruded by the basalt. The K/Ar age of 1.46ñ0.18 my yielded by the basalt sample verifies the earlier proposal by Acosta et al. (Mar. Pet. Geol. 128 (2001a) 349) that the volcanism that created part or all of Emile Baudot Seamount and the Southwest Majorca Volcanic Field associated with the seamount took place in the Pleistocene. This volcanism is probably related to decompression resulting from the normal faulting that led to the subsidence of the low (Central Depression) between Ibiza and Majorca (Balearic Islands).
Resumen: A complete multibeam coverage of the sea floor of Mallorca Channel, in the western Mediterranean, was recorded during
the Spanish Exclusive Economic Zone surveys in 1995, 1996 and 1997. These data, combined with previous high-resolution
seismic reflection profiles, allow an assessment of the geomorphology of the area. The
channel seafloor is disrupted by a fault
complex and pockmarks. Motion along the faults split the sea floor into a series of undulations separated by narrow V-shaped
notches. Faulting may be a consequence of recent seaward gravitational sliding that occurred along a soft surface at the top of a
late Messinian–early Pliocene unit and a late Messinian evaporite. These units have been tilted during recent subsidence of the
Mallorca Channel at the same time that the insular shelf was uplifted along a fault at the shelf’s edge. The set of pockmarks in
the channel sequence were probably formed by the expulsion of gas of hydrothermal origin, and expulsion may have been
enhanced by the faulting. This gas seepage could be an additional factor leading to sediment instability.
