Airborne spectral sensing of Hydrothermal Alteration Minerals

Remote sensing infrared spectrometer data were collected with the Geophysical and Environmental Research Corp. 64 channel scanning spectrometer. These have been used to delineate geological units and, subject to some ambiguity, identify their mineralogy. Results are given for a survey area near Coppin Gap in the Pilbara region of Western Australia. Here, clear distinction was obtained between the sericite mineralogy of the Hardey Sandstone and some members of the Marble Bar belt, and the carbonate or epidote/chlorite mineralogy of the Kylena Basalt and other units in the Marble Bar belt.

From the airborne spectrometer data it was also possible to identify and map the occurrence of the mineral pyrophyllite. Analysis of field samples confirmed the identification and provided evidence that the technique was indeed mapping the occurrence of this mineral.

The applicability of this technique has been assessed from other surveys in Australia, and it appears to require good geological exposure and sparse vegetation. There is some scope for extension of its applicability through further instrumental developments.