Cenozoic sedimentary provenance of the Central Sumatra Basin

Amy Gough & Robert Hall

Aims

The Eocene-Miocene deposits of the Central Sumatra Basin were deposited in similar environments to those of the South Sumatra Basin. A comprehensive study into the clastic sediments of the Pematang and Sihapas formations of the Central Sumatra Basin will allow comparisons between the basins to be drawn, as well as any connectivity to be analysed. This will be achieved through a provenance study, including classical field data, a heavy mineral study, and single-grain geochronology.

Background

The Central Sumatra Basin sits towards the east of the Barisan Mountain Chain, which forms the ‘back-bone’ of Sumatra. Like the South Sumatra Basin, it is considered to be a ‘back-arc’ basin, despite the fact it pre-dates the development of the Sumatran Arc. Throughout the Eocene-Oligocene these eastern basins were in a ‘horst and graben’ stage of development, creating smaller depocentres for sediment accumulation. These deep-rift basins allowed for deposition of Pematang alluvial and fluvial systems shed from localised highs, which interacted with basin-centre lacustrine environments, mimicking the deposits found in the SSB.

By the Miocene the Sihapas Formation had begun being deposited. At this point, smaller sub-basins had reached a state of overfill and sediments were deposited in a series of proximal fans, braided fluvial systems, and marginal marine environments. It is possible that these depositional environments were connected to the environments found in the SSB before the uplift of the Tigapuluh Mountains.

Recent Papers –

Max Webb et al., 2020. Isotopic mapping reveals the location of crustal fragments along a long-lived convergent plate boundary. Lithos.

https://doi.org/10.1016/j.lithos.2020.105687

Max Webb et al., 2020. The history of Cenozoic magmatism and collision in NW New Guinea – New insights into the tectonic evolution of the northernmost margin of the Australian Plate. Gondwana Research.

https://doi.org/10.1016/j.gr.2019.12.010

Amy Gough et al., 2020. Mid-Cenozoic fluvio-deltaic to marine environments of the Salin Sub-basin, Central Myanmar. Journal of Asian Earth Sciences.

https://doi.org/10.1016/j.jseaes.2019.104143

Recent News –

Amy Gough and Max Webb attended the Restech 2.0 Virtual Reservoir Conference. Amy Gough presented new SEARG research on the pitfalls of light mineral studies for sedimentary provenance in tropical climates.

Amy Gough was awarded an honorary research fellowship of the British Geological Survey and continues to foster collaborative relationships between SEARG and the BGS.