RT Journal Article
SR Electronic
T1 Hydrogeochemistry as an aid to geological interpretation: the Glen Roy area, Scotland
JF Journal of the Geological Society
JO Journal of the Geological Society
FD Geological Society of London
SP 839
OP 852
DO 10.1144/gsjgs.153.6.0839
VO 153
IS 6
A1 EDMUNDS, W. M.
A1 KEY, R. M.
YR 1996
UL http://jgs.lyellcollection.org/content/153/6/839.abstract
AB The hydrochemistry of first and second order streams, sampled at a density of 1 km2, has been used to investigate ways of enhancing information obtained during regional geological mapping. The Glen Roy area of Scotland is a pristine area with large variations in bedrock geology, ranging from Dalradian metasediments (including carbonates), to granite, granodiorite and appinite rocks (coarse-grained lamprophyre) but with relatively minor drift.Alkalinity (HCO3,) is used to determine the extent of water-rock interaction with both silicate and carbonate rocks. The ratio Na/Cl is also used to measure the extent of silicate reaction: dolomitic facies are picked out in areas with carbonate by Mg. Mn, Fe and Y are useful indicators of the weathering of biotite and garnet. A strong and well defined hydrogeochemical anomaly of Ba, Sr and K outline the outcrops of the appinites. Together with HCO3, these three elements define an extended NW–SE lineament (Strath Ossian Lineament) which includes possible concealed areas of appinite, the bicarbonate probably reflecting the presence of a carbonate aureole derived from mantle CO2. In particular the bedrock characteristics in poorly exposed ground can be inferred and information obtained on the volume of bedrock through which the water has passed.