Stratigraphic studies on Timor-Leste

[Truncated abstract] In order to better understand the Triassic stratigraphy of Timor, the succession is reconstructed using a new extensive stratigraphic database together with published data. A stratigraphic subdivision is proposed based on units defined by lithological changes synchronous throughout Timor and these are used as a basis for a second-order sequence stratigraphic framework. This new view of the Triassic stratigraphy is used to investigate: (1) depositional systems present during the main interval of Babulu Group deposition; (2) the potential tectonic settings within which these may have been active; and (3)comparisons with Triassic successions elsewhere in northeastern Gondwana. From this analysis, mechanisms that drove the development of the Triassic succession in Timor are reassessed.

The reconstructed succession is divided into four gross lithological units (GLU TR1-TR4) that form the basis of a second-order sequence stratigraphic framework comprising two sequences (SOS ‘A’ and ‘B’). Strata typically attributed to the Babulu Group, widely assumed to have been deposited within an active extensional tectonic regime, dominate GLU TR2. This unit spans the late Anisian to late Carnian and is placed within the highstand systems tract of SOS ‘A’ and the lowstand systems tract of the SOS ‘B’. The boundary between GLU TR2 and the overlying GLU TR3 represents a second-order transgressive surface that appears to have regional significance, albeit with variable expression. To assist in assessing the mechanisms that drove the development of GLU TR2, and the Triassic succession in general, sixteen key facies are described here that together form eleven key facies associations and one lithostratigraphic group, the Bandeira Group.