The second field season in North-Eastern Kalimantan (Borneo) took place between March and December 1980. This work was carried out within the framework of a three-year cooperation agreement between France and Indonesia, signed in Jakarta, On Febuary 5, 1979.

During thisw field season, a surface area of 15,500 km2 was prospected with a density of 1 stream sediment geochemical sample and 1 pan concen trate per 5.9 km2, with mapping carried out on a scale of 1:250.000.

This work was accompalished by 5 BRGM expatriate geologist who were assisted by 4 Indonesian geologist and 12 prospectorrs and technical assistants from the Directorate of Mineral Resource in Bandung (Geological Survey of Indonesia) .

The geological survey carried out in 1980 made it possible to complete and sometimes modify ideas resulting from the 1979 field season. Sedimentary areas, mostly of the flysch type, presumed to be Upper Cretaceous to Miocene in age, are mainly represented by stanstones, siltstones and argillites. In some formations, limestones, sometimes reefal, apper. Pyroclastics of trachy-andesitic composition crop out in the south-west of the sector. intrusive rocks, dioritic and gabbroic, are very rare.

Mineralized occurrences obseved at outcrop are not particularly encouraging. pyrite was the only sulphide noted. HOwever, high quality coal has been found in the Upper Kerayan, in beds up to1,5 m thick. Salt springs are also exploited by the local population of the area. The results to geochemical analyses to be carried out at Orleans, as well as heavy mineral determinations to be completed at Bandung, will enable the metallogenic interest of the prospected in 1980 to be specified.

Panning prospecting carried out in 1979 did however reveal considerable mineralization in terms of cinnabar, which occurs in 417 concentrates out of a total of 2,411. Small quatities of gold were also observed 14 concentrates.

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