Reconnaissance palaeomagnetic results from sulawesi, indonesia, and their bearing on palaeogeographic reconstructions

Abstract

Magnetic remanence of Jurassic radiolarian chert from the southwest arm of Sulawesi (Celebes) yields a palaeomagnetic pole at 55°N,32°E, indicating rotation of about 35° anticlockwise since the late Mesozoic. This pole is close to those obtained from Cretaceous rocks of the Malay Peninsula and West Kalimantan and suggests that the three areas may have formed part of the same plate since the late Mesozoic, or at least that Sulawesi has not moved much relative to the other two areas. Measurements from Jurassic cherts from the southeast arm of Sulawesi show a magnetic inclination of 61° ; although too few samples were obtained for firm conclusions to be drawn, this does suggest that the cherts in the southeast arm were formed at higher latitudes and is compatible with the hypothesis that eastern Sulawesi was part of an Australian plate and was welded onto west Sulawesi in the Cainozoic. Measurements on tuffs, sills and lavas of late Cainozoic age on the flanks of the Lompobatang volcano mostly show directions near the existing field, four sites in a reversed sense, and one normal.