Environmental Biogeochemistry Research Group | Research Themes

Fluid chemistry
The variation in the chemistry of geothermal fluids provide information regarding the origins, mixing and flow regimes of the systems. Through a series of projects standard methods in monitoring and modelling the behaviour of geothermal fluids wee developed. Later work has illustrated the links between terrestrial and marine geothermal fluids, the mineralising fluids of base and precious metal deposits and the formation water of oil-field reservoirs.

NICHOLSON, K. (1993). Geothermal fluids: Chemistry and Exploration Techniques. Springer-Verlag, Berlin 268pp, ISBN 0 387 56017 3.

KEYWOOD, M. and NICHOLSON, K. (1990). Cyclic and temporal changes in water chemistry of Inferno Crater, Waimangu Geothermal Valley, New Zealand. In: Harvey C.C., Browne, P.R.L., Freestone, D.H. and Scott, G.L. (eds), Proc. 12th NZ Geothermal Workshop, Auckland University Press, Auckland, ISBN 0-86869-012-0, 103-110.

SALVANIA, N.V. and NICHOLSON, K. (1990). Chemometrics applied to the fluid chemistry of geothermal fields in the Taupo Volcanic Zone, New Zealand. In: Harvey C.C., Browne, P.R.L., Freestone, D.H. and Scott, G.L. (eds), Proc. 12th NZ Geothermal Workshop, Auckland University Press, Auckland, ISBN 0-86869-012-0, 157-163.

KEYWOOD, M., RODGERS, K.A. and NICHOLSON, K. (1992). A catalogue of active thermal features in the Waimangu Valley, 1990. New Zealand Volcanological Record, 19, 29-51.

NICHOLSON, K. (1994). Fluid chemistry and hydrological regimes in geothermal systems: a possible link between gold-depositing and hydrocarbon-bearing aqueous systems. In: Parnell, J., (ed), Geofluids: Origin, Migration and Evolution of Fluids in Sedimentary Basins. Geological Society Special Publication No. 78, Geological Society Publishing House, 221-232.

Environmental impacts
All energy resources have environmental impacts, and this work evaluates and reviews the impacts of geothermal energy on aquatic, terrestrial and biological systems.
NICHOLSON, K. and LIU WEI (1991). Energy resources and the environment: influence of natural boron emissions on soil chemistry over two geothermal resources in New Zealand. In: Selinus, O. (ed.) Second international symposium on environmental geochemistry. Abs. Swedish Geological Survey, Rapp. & Medd., 69, ISBN 91-7158-501-X, 179.

NICHOLSON, K. (1992). Environmental impact of geothermal resources: Examples from New Zealand. In: Sayigh, A.A.M. (Editor) Renewable energy, technology and the environment. Pergamon Press, 2895-2899.

NICHOLSON, K. (1998). Geothermal energy and the environment. In: NICHOLSON, K. (Editor). Energy & the Environment. Geochemistry of fossil, nuclear & renewable resources. Environmental Geochemistry Series Volume 1, MacGregor Science. ISBN 0-9520950-5-X

Petrographic and geochemical criteria for the recognition of silica sinters
Silica sinters provide a guide to modern and ancient geothermal-epithermal hydrothermal systems and are therefore a useful guide to gold exploration. This study developed petrographic and geochemical criteria to differentiate between sinters and other siliceous lithologies; and developed diagnostic geochemical signatures to discriminate between barren and gold-bearing fossil systems.

NICHOLSON, K. and AQUINO, C. (1989). Life in geothermal systems. A key to sinter formation and recognition? In: Browne, P.R.L. and Nicholson, K. (eds), Proc. 11th NZ Geothermal Workshop, Auckland University Press, Auckland, ISBN 0-86869-071-6, 143-148.

PARKER, R.J. and NICHOLSON, K. (1990). Arsenic in geothemal sinters: Determination and implications for mineral exploration. In: Harvey C.C., Browne, P.R.L., Freestone, D.H. and Scott, G.L. (eds), Proc. 12th NZ Geothermal Workshop, Auckland University Press, Auckland, ISBN 0-86869-012-0, 35-39.

NICHOLSON, K. and PARKER, R.J. (1990). Geothermal sinter chemistry: Towards a diagnostic signature and a sinter geothermometer. In: Harvey C.C., Browne, P.R.L., Freestone, D.H. and Scott, G.L. (eds), Proc. 12th NZ Geothermal Workshop, Auckland University Press, Auckland, ISBN 0-86869-012-0, 97-102.

Soil mineralogy and chemistry over geothermal systems
In both the exploration for geothermal energy resources and in evaluating the environmental impacts of a resource, a knowledge of the soil chemistry and changes induced over a geothermal system are significant. Vapour-borne and water-borne species both interact with the mineral and organic-rich horizons to produce distinct mineralogical and geochemical anomalies over permeable and upflow zones. The behaviour of boron and ammonia over geothermal systems was given particular attention in the development of novel soil geochemical exploration methods.

NICHOLSON, K. and AREDES, S. (1989). Soil ammonia as a pathfinder to geothermal resources. In: Proc. New Zealand Geochemical Group Conference, Wairakei, 11.

NICHOLSON, K., FRANKLYN, A.K. and AREDES, S. (1989). Geochemical soil surveys as an exploration technique for low-enthalpy geothermal resources. In: Browne, P.R.L. and Nicholson, K. (eds), Proc. 11th NZ Geothermal Workshop, Auckland University Press, Auckland, ISBN 0-86869-071-6, 189-193.

AREDES, S. and NICHOLSON, K. (1990). Ammonia in soils: A new technique in geothermal exploration. Geoth. Res. Council Trans., 14, 1371-1376.

CONG, S., VARGAS, E.P., BROWNE, P.R.L., HARVEY, C.C. and NICHOLSON, K. (1990). Spatial distribution of surface alteration and ground temperature at Wairakei Thermal (Geyser) Valley, New Zealand. In: Harvey C.C., Browne, P.R.L., Freestone, D.H. and Scott, G.L. (eds), Proc. 12th NZ Geothermal Workshop, Auckland University Press, Auckland, ISBN 0-86869-012-0, 267-271.

LIU WEI and NICHOLSON, K. (1990). Boron in soils over Naike and Whitford low-enthalpy geothermal fields, New Zealand. In: Harvey C.C., Browne, P.R.L., Freestone, D.H. and Scott, G.L. (eds), Proc. 12th NZ Geothermal Workshop, Auckland University Press, Auckland, ISBN 0-86869-012-0, 177-182.

NICHOLSON, K. (1994). Soil geochemistry in exploration for low-enthalpy geothermal resources: ammonia and boron surveys. Geothermics in Europe, BRGM, 230, 75-81.

Fossil remnants of geothermal systems as a guide to potential epithermal gold deposits
In addition to the identification of silica sinters, mineralogical and geochemical criteria have been developed to recognise steam zones, hydrothermal breccias, hydrothermal precipitates and boiling zones. The application of these criteria lead to the identification of several fossil systems in NE Scotland.

NICHOLSON, K. (1988). Geothermal deposits in ancient terrain as a tool in epithermal gold exploration: examples from Scotland. In: McKibbin (ed.) Proc. 10th New Zealand Geothermal Workshop, Auckland University Press, Auckland, ISBN 0-86869-026-0, 151-153.

NICHOLSON, K. (1989). Early Devonian geothermal systems in North-east Scotland: Exploration targets for epithermal gold. Geology, 17, 568-571.