Cempaka Diamond Deposit

Lloyd White, Ian Graham, Dominique Tanner, Robert Hall & Richard Armstrong

Aims

This study aimed to determine the enigmatic source for the Cempaka paleo-alluvial diamond deposit. To do this, we: (1) dated detrital zircons to understand the age of potential source material; (2) obtained geochemical data from Cr-spinels to verify if a kimberlite/lamproite source was evident, and; (3) examine the morphology and age of the zircon grains relative to the morphology and chemistry of diamonds to test the tectonic model(s) that have previously been proposed to explain the origin of the Cempaka diamonds.

Background

Several gem quality diamond deposits are found within paleo-alluvial sediments in several locations in southern Borneo. Various models have been proposed to explain the origin of these diamonds. They may have been emplaced in kimberlite/lamproite pipes in Borneo or could be related to diamond deposits in NW Australia, and carried with the Southwest Borneo Block after it rifted from Australia in the Late Jurassic. Alternatively, the diamonds could have been produced in subduction zones in Asia, and were later transported to Borneo via major river systems.

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.