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Aqueous Geochemistry in Mineral Exploration

Matthew I. Leybourne, GNS Science, Avalon, Lower Hutt, New Zealand

GNS Science

Outline

• Why aqueous geochemistry in mineral exploration?

• Field analyses - importance of pH and Eh

• Major species

• Trace metals and metalloids

• Stable isotopes

• Radiogenic isotopes

• Insights gained from water chemistry

• Seawater exploration for SMS

GNS Science

Utility of groundwater geochemistry

• Significant challenge for mineral exploration is to find new and deeper deposits, particularly in areas where either thick cover exists

• Where past exploration has already discovered shallow mineralization and exploration must extend to greater depth

• Groundwater recharges to depth, resulting in greater likelihood of interacting with buried mineralization compared to surficial geochemical methods, thus providing a three dimensional perspective

• Aqueous geochemistry can provide insights into other sample media and dispersion processes, secondary mineral formation

GNS Science

Natural waters vs AMD

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Field based analyses

- pH and redox

KZK (Yukon) Spence (Chile)

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Major species: Monturaqui, Salar de Punta Negra

and Hamburgo Basin

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Major species: Kirkland Lake,

Ontario

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Trace metals and metalloids

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Trace elements - Spence, Chile

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Trace elements - Spence, Chile

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Trace elements - KZK, Yukon

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Trace elements - Bathurst Camp, NB

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Trace elements - Bathurst Camp, NB

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Filtration versus non-filtration

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Stable Isotopes - Spence, Chile

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Stable isotopes

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Stable isotopes - KZK, Yukon

Layton-Matthews and Leybourne (unpublished data)

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Fingerprinting trace metal sources

de Caritat, P. and Kirste, D., (2005)

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Radiogenic isotopes - Pb

• Pb has low solubility in waters

• Distinguishing true from false anomalies (organic, Mn or Fe oxide

accumulation of metals)

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Radiogenic isotopes

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Integration of geochemical modeling with real-

world examples

• Enhanced understanding of critical processes

• Application to metallurgical processes, remediation studies, supergene

mineralization

Formation of atacamite

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Formation of soil anomalies

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Aqueous

Geochemical

Exploration: The

Oceans

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Plume Hunting

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1.0

1.4

1.8

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Sometimes the water comes to you…

26th International Applied Geochemistry Symposium Incorporating the New Zealand Geothermal Workshop

18-21 November, 2013, Rotorua, New Zealand

www.gns.cri.nz/iags