SEA-FLOOR SPREADING MAGNETIC-ANOMALIES IN THE SOUTHEASTERN ARABIAN SEA

Study of closely spaced new marine magnetic pro files in the southeastern Arabian Sea has enabled fairly confident identification of E-W trending linear magnetic anomalies 24 through 20. These magnetic lineations are consistently right laterally offset along numerous fracture zones and extend eastwards up to the base of the western slopes of the Laccadive Ridge. Obliteration of magnetic lineations further eastward is attributed to the emplacement of volcanic material of the Laccadive Ridge over the pre-existing oceanic crust. DSDP Site 221 is observed to be located on the reversely magnetized oceanic crust between anomalies 22 and 21 which provide a reliable age constraint (48 Myr) for the oceanic crust at this site. The presence of additional unidentifiable normal magnetic anomalies suggests a relatively complex spreading pattern (ridge jump?) in the vicinity of the Laccadive Ridge during the interval of anomalies 24 and 23.