Determination of geochemical background pattern of surface waters in an ultramafic and non-anthropic context: Koniambo massif, New-Caledonia

TitreDetermination of geochemical background pattern of surface waters in an ultramafic and non-anthropic context: Koniambo massif, New-Caledonia
Publication TypeConference Proceedings
Year of Publication2014
AuthorsBoula, A, Laporte-Magoni, C, Gunkel-Grillon, P, Selmaoui-Folcher, N
Conference NameInternational Conference on Oceans and Rivers (ICOR2014)
Date Published10/2014
Abstract

Koniambo’s massif is characterized by ultramafic rocks with peridotites, serpentinites, and laterites. These lithologies are rich in metallic elements as nickel, cobalt, iron, chromium, magnesium. This work completes papers of Barnes, Neil, and Trescases (1978) presenting a comparison between water chemistry in ophiolitic catchments in USA ((Barnes and O’Neil,
1969), Oman (Stanger, 1986 and Dewandel et al. 2005), and Cyprus (Colin and Shand, 2002)). Then, to determinate a geochemical background of metals in surface waters, a study and an analysis of the pre-mining survey database is performed for ultramafic catchments on the nickeliferous massifs. In this study, metallic background is defined with both dissolved and total element compositions. Statistic tests attest of a geochemistry depending mostly of rock mineralogy. In order to define the metallic elements that could be used as markers of mining anthropisation, a comparative approach has been done with impacted and non impacted ultramafic catchments. For this, we compare four ultramafic non-anthropic small catchments and one catchment impacted by past mining activity. As expected in such a geological context, the chemical elements Ni, Cr and Fe are identified as markers of mining extractions. In addition, quite unexpectedly over the compositions of rocks, Zn and As were also identified as potential impact indicators. Moreover, we highlighted a geochemical profile that characterizes the chemical signatures of catchments not affected. This pattern based on 4 signatures, will constitute the geochemical background model for ultramafic non-anthropic environment and will be considered as a main constituent of original state for mining company.
All these results have been validated statistically on data provided from mining company