Main features of the basic rock bodies of the Archidona Region derived from geophysical data (External Zones, Betic Cordillera)

The basic igneous rock bodies that crop out in the Archidona region are com posed of ophites. Their small size, however, does not justify the total fie ld aeromagnetic anomaly observed, which reaches up to +70 nT. New magnetic, P-wave seismic tomography and gravity data allow the characterization of t he geometry of the basic rock bodies located in the middle and upper crust. The most important one is a kilometric body between at least 5 and 18 km i n depth, probably at the basement of the External Zones and possibly belong ing to the Iberian Massif. (C) 2000 Academie des sciences/Editions scientif iques et medicales Elsevier SAS.