Applying integrated Triassic biostratigraphy in Timor-Leste to unlock an under-sampled Gondwanan sector of the Tethys puzzle

Abstract

The contribution to Tethyan and global Triassic studies from the Australian sector of southeastern Tethys is limited relative to that from the Himalayan sector. Whilst many of the Triassic successions from the Australian sector are located offshore, one succession is exposed on the island of Timor. This marine succession, dismembered during collision between the Australian continent and the volcanic Banda Arc, has been investigated for over 100 years but has also made limited modern contributions to Tethyan and global Triassic studies. To address this a new integrated Triassic biostratigraphic microfossil database (conodonts, palynomorphs and radiolarians) from Timor-Leste is presented here that compliments published foraminiferal data. This integrated data set 1) supports application in Timor of the endemic palynomorph zonal scheme from the North West Shelf of Australia whilst providing additional ties for this to the Geological Time Scale (GTS), 2) provides paleobiogeographic support for accumulation of the Timor-Leste Triassic succession within a southeast Tethyan Gondwanan basin and informs discussions about Tethyan paleobiogeography, 3) calibrates over 300 outcrops to the GTS enabling an improved reconstruction of the dismembered succession that will facilitate enhanced regional and local paleogeographic and tectonostratigraphic assessments, and 4) provides independent GTS calibration for published basinal foraminiferal assemblages which will assist understanding the biostratigraphic utility of these assemblages. This database identifies key outcrops, such as the first outcropping Permian-Triassic Boundary section from this sector of southeastern Tethys, that will facilitate targeted studies addressing a range of Tethyan and global Triassic issues unlocking insights from an under-sampled Gondwanan sector of Tethys.