The identification of various types of geochemical stream sediment anomalies in Northern Ireland

doi:10.1016/0375-6742(79)90013-X

Journal of Geochemical Exploration

Volume 11, Issue 1, May 1979, Pages 13-32

https://doi.org/10.1016/0375-6742(79)90013-X Get rights and content

Abstract

A regional geochemical stream sediment survey of part of Northern Ireland led to the recognition of three types of base metal anomaly of exploration interest. These were significant anomalies of both elastic and hydromorphic origin, and non-significant hydromorphic anomalies in several upland areas. The significant anomalies are derived from Pb-Zn-Cu mineralization, whereas the non-significant anomalies are due to the leaching of Zn and other metals from acidic and/or gleyed soils and subsequent concentration in stream channels by coprecipitation with manganese oxides. Significant hydromorphic anomalies can be identified on the basis of abnormal Zn/Mn ratios and significant elastic anomalies on the basis of anomalous Pb contents. It is of the utmost importance to distinguish the dispersion mechanisms. Regional variations in bedrock geochemistry may only be identified when consideration is given to local dispersion mechanisms and account taken of the effects of variations in the surface environment on stream sediment composition. Changes in vegetation and land use may lead to rapid alterations in the nature of the dominant dispersion mechanisms.

References (26)

R.H. Carpenter et al.
Fe-Mn oxide coatings in stream sediment geochemical surveys
J. Geochem. Explor.
(1975)
K.B. Krauskopf
The separation of manganese from iron
Geochim. Cosmochim. Acta
(1957)
P. Loganathan et al.
Sorption of heavy metal ions by a hydrous manganese oxide
Geochim. Cosmochim. Acta
(1973)
J.W. Murray
The interaction of cobalt with hydrous manganese oxides
Geochim. Cosmochim. Acta
(1975)
G.A. Nowlan
Concretionary manganese-iron oxides in streams and their usefulness as a sample medium for geochemical prospecting
P.R. Whitney
Relationships of manganese-iron oxides and associated heavy metals to grain size in stream sediments
J. Geochem. Explor.
(1975)
Provisional geochemical atlas of Northern Ireland
Appl. Geochem. Res. Group, Imperial Coll., Tech. Comm.
(1973)
J.W. Arthurs
The geology and metalliferous mineral potential of the Sperrin Mountains area
Mem., Geol. Surv. N. Irel.
(1976)
C.R.M. Butt
The influence of environment on regional geochemical patterns in Northern Ireland
G.A.J. Cole
Localities of minerals of economic importance and metalliferous mines in Ireland
Mem., Geol. Surv. Irel.
(1922)

J.F. Collins et al.

Effects of fluctuations in the Eh-pH environment on iron and/or manganese equilibria

Soil Sci.

(1970)

Geological Survey of Northern Ireland

Mineral Resources Map. Belfast

(1970)

H.E. Hawkes et al.

Geochemistry in Mineral Exploration

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A sequential extraction scheme is utilized to determine the geochemical partitioning of Cu, Zn and Pb among hydrous Mn- and Fe-oxides, organics and residual crystalline silicates and oxides in the minus-80-mesh (< 0.18 mm) sediments and in boulder coatings from a stream in Lincoln County, Georgia (U.S.A.). The stream drains an area containing a CuZnPb-sulfide deposit (Magruder Mine). The boulder coatings contain mainly Mn-oxides and organics, with minor hydrous Fe-oxides. In the sediment, the chemically active phases are mainly hydrous Fe-oxides and organics, probably because Mn is leaching out of the sediments and precipitating on the exposed surfaces of boulders. In the boulder coatings, competition among Fe- and Mn-oxides and organics for Cu, Zn and Pb follows the order: Cu, organics > Fe-oxides > Mn-oxides; Zn, $Mn-oxides ⋍ organics > Fe-oxides$ ; Pb, Fe-oxides > organics > Mn-oxides. In the sediments, organics are the most efficient scavengers of all three ore metals. These results emphasize the importance of organics as sinks for the ore metals, even in environments with high concentrations of Mn- and Fe-oxides.
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Research paperThe identification of various types of geochemical stream sediment anomalies in Northern Ireland

Abstract

J. Geochem. Explor.

Geochim. Cosmochim. Acta

Geochim. Cosmochim. Acta

Geochim. Cosmochim. Acta

J. Geochem. Explor.

Provisional geochemical atlas of Northern Ireland

Appl. Geochem. Res. Group, Imperial Coll., Tech. Comm.

The geology and metalliferous mineral potential of the Sperrin Mountains area

Mem., Geol. Surv. N. Irel.

The influence of environment on regional geochemical patterns in Northern Ireland

Localities of minerals of economic importance and metalliferous mines in Ireland

Mem., Geol. Surv. Irel.

Effects of fluctuations in the Eh-pH environment on iron and/or manganese equilibria

Soil Sci.

Mineral Resources Map. Belfast

Geochemistry in Mineral Exploration

Research paper
The identification of various types of geochemical stream sediment anomalies in Northern Ireland