Bedrock lithologies comprise strongly altered (haematite- epidote-silica) mafic volcanics and epiclastic
sediments on the northern margin of the Burns granitoid intrusive.
Albitisation is reported in deep weathering profiles [1, 2], in epiclastic
sediments during diagenesis and low-grade metamorphism , in granitoids during late magmatic alteration , and in association with fluid migration in mobile belts .
Furthermore the occurrence of strong winds, due to the exposition of the island, and the steep volcanic surfaces don't allow the accumulation of epiclastic
deposits possibly produced by the erosional processes.
An exposed outcrop of volcaniclastic (epiclastic
) deposits is observed and described at the eastern foothills of G.
The VSC is represented by subaerial to marine felsic and mafic volcanic (Routhier et al., 1980), and epiclastic
volcanic sediments; the Culm Group, constituting the stratigraphic top of the Pyrite Belt, comprises a succession of shales and greywackes; turbidite and flysch Unit (Moreno, 1993).
The Main-a-Dieu Group consists of mainly tuffaceous sedimentary and epiclastic
rocks, with minor basaltic and rhyolitic flows, interpreted by Barr et al.
Manassero, M.J., Zalba, P.E., Andreis, R.R., Morosi, M., Petrology of continental pyroclastic and epiclastic
sequences in the Chubut Group [Cretaceous]: Los Altares-Las Plumas area, Chubut, Patagonia Argentina, Rev.
Bright yellow, highly birefringent smectite forms argillan rims around the mineralogically stable epiclastic
grains (mainly quartz) and pseudomorphs them.