Sea-Floor Spreading in the Wharton Basin (Northeast Indian Ocean) and the Breakup of Eastern Gondwanaland

Gondwanaland Dispersal and the Early Formation of the Indian Ocean

“…The distribution of isochrons in Figure 2 indicates that eastern India was most likely against Antarctica in Gondwanaland as suggested earlier by DuToit (1937), McElhinney (1970), Falvey (1972b, and Smith and Hallam (1970), and that the dispersal plate system was initiated first off northwest Australia, followed by spreading between India and Antarctica. Figure 3a shows an east-west-trending ridge off northern Australia and India (?…”

“…These anomalies are early Tertiary in the northern Wharton Basin, and evidently Early Cretaceous in the North Australia Basin. Earlier, Falvey (1972b) apparently misidentified this latter set of anomalies as Cenozoic, but the drilling results imply they are older. Attempts to model this sequence using Larson and Pitman's (1972) Mesozoic time scale and various combinations of spreading rates and skewness, θ (Schouten and McCamy, 1972) have not yet been successful, and there is some doubt as to whether these anomalies are related to sea-floorspreading processes.…”

Gondwanaland Dispersal and the Early Formation of the Indian Ocean

“…This reconstruction predicts continental conditions and sedimentation in extreme western Australia until the Early Cretaceous, a condition which is required by geologic data from this region (Veevers, 1971). A larger than usual India is shown in this reconstruction, the northeastern boundary being defined by north-trending structures (Falvey, 1972b;Dickinson, 1971) and seismicity (Barazangi and Dorman, 1969) in western Burma. The configuration of the Gondwana continents shown in Figure 4a is not greatly different from that suggested by DuToit (1937), andMcElhinney (1970), among others, and seems to satisfy much equivocal geologic data and more stringent paleomagnetic results.…”

“…The sea floor here is older than that in the southern Wharton Basin, implying that rifting and spreading occurred here first. East-westtrending marine magnetic anomalies have been mapped in the northern Wharton Basin by Sclater and Fisher (in press) and Lowrie et al, (1972), and in the North Australian Basin by Falvey (1972b). These anomalies are early Tertiary in the northern Wharton Basin, and evidently Early Cretaceous in the North Australia Basin.…”

Comparative Stratigraphy and Structure of the Western Australian Margin and the Adjacent Deep Ocean Floor

“…The only set of trends known from the sea floor off the northwest margin-the magnetic lineations between the Exmouth Plateau and Roo Rise, and in the northeast Argo Abyssal Plain (Falvey, 1972)-parallel the fault patterns on the continental margin. The Darling Fault, which is a Proterozoic feature reactivated in the Permian and Mesozoic to form the eastern margin of the Perth and southern Carnarvon basins, trends in a north-south direction in marked contrast with the dominant northeast and northwest trends.…”