The Geology of Portuguese Timor

Abstract

Abstract The oldest dated rocks in eastern Timor are of Lower Permian age, the metamorphic rocks of uncertain age being interpreted as probably pre-Permian. With the exception of two important breaks and a number of minor but widespread unconformities (affecting all eastern Timor) from Permian times onwards the stratigraphical record is fairly continuous to the Holocene. Some formations are entirely allochthonous in eastern Timor. The present work attempts a complete revision of the stratigraphical column. This entails the definition of many new formations, the revision of the limits of others, and their re-positioning in the time-sequence. All field mapping and stratigraphical subdivisions were based on lithostratigraphical units. Fossils collected from these various units and identified by specialists have provided the time-control. The recommendations of the Australian Code of Stratigraphic Nomenclature (4th edition, 1964) are followed as closely as possible. Grunau (1953) recognized that some rocks of eastern Timor were technically allochthonous and divided the formations into an autochthonous and allochthonous complex. Gageonnet & Lemoine (1958) followed Grunau in this procedure. The uncertainties of these and earlier workers over which formations are allochthonous are now dispelled; most of the formations are now recognized as autochthonous. Four separate formations are recognized as completely allochthonous: the Lolotoi Complex, Aileu Formation, Maubisse Formation and Bobonaro Scaly Clay. Of these the Bobonaro Scaly Clay is distinct in that it was emplaced in Timor as a submarine gravity slide (Audley-Charles 1965a). Unlike all the other allochthonous formations it does not rest on a thrust-plane. The Bobonaro Scaly