
%0 Journal Article
%A Howlett, A. 
%A Roach, M.J. 
%A Reid, J.E. 
%T Geophysical characteristics of salinisation at Cape Portland, NE Tasmania
%J Exploration Geophysics
%D 2001/12/01
%V 32
%N 4
%P 214-218
%K 
%R https://doi.org/10.1071/EG01214
%U https://www.publish.csiro.au/paper/EG01214 
%X An integrated geophysical study of salinisation at Cape Portland, NE Tasmania, has mapped the distribution of saline areas, identified constrictions in the hydrogeologic basement and a possible source, store and transport mechanism for the salt. EM-31 data not only clearly delineates the extent of salt scalds, but also highlight areas of elevated conductivity not visibly affected by salt. EM-31 data maps the distribution of the salt at a much higher resolution than was previously possible using shallow drilling. Results from time-domain electromagnetic surveys confirm the responses seen in the EM-31 data and provide additional information about the subsurface distribution of conductive material. Conductivity depth pseudosections and layered earth inversions indicate depressions of up to 100 m in the resistive basement that are infilled with more conductive material. Ground magnetic data show the distribution of shallow Jurassic dolerite basement features and define a major negative anomaly that transects the study area. This feature is coincident with depressions identified from the time-domain electromagnetics and with a negative Bouguer gravity anomaly. The electromagnetic and potential field interpretations are consistent and indicate the presence of a major palaeochannel infilled with conductive material that cross-cuts the study area. Seismic refraction surveys and shallow auger holes in this zone provide additional support for the presence of a palaeochannel. This feature is inferred to be a major control on salinisation at Cape Portland. 
