Abstract

Dr A. E. Grady commented that he and his colleagues from the Flinders University of South Australia continued to doubt the complete validity of the model for the tectonic development of Timor proposed by Professor Audley-Charles et al. Doubts related specifically to the significance of, and amounts of movement on thrusts in the island. As this is the subject of existing publications (Grady 1975; Barber et al. 1977; Chamalaun 1977 a, b; Grady & Berry 1977; Chamalaun & Grady 1978; Audley-Charles et al. 1978) it need not be developed further in this context.

Dr Grady outlined some of the features of the Aileu Formation occurring on the N coast of E Timor between Dili and Manatuto, the results (unpublished) of a research study carried out over 4 years mainly by Mr R. F. Berry while a student at Flinders University of South Australia.

The Aileu Formation in this area (c. 40 × 10 km) is composed in the W of mainly pelitic phyllites, with occasional psammites, metabasic rocks and rare limestones. In the E, interlayered marbles, amphibolites and pelitic schists predominate and are found with psammitic schists and one layer of altered ultrabasic rocks. Mesoscopic and macroscopic structural analysis revealed a multi-deformational history of perhaps 5 deformational phases:

D1 resulted in the development of a penetrative foliation (cleavage or schistosity) across the area, sub-parallel to lithological layering. No folds can definitely be attributed to this deformation.

D2 developed a second penetrative foliation (cleavage, schistosity, gneissosity), generally at a low angle

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