Geochemical anomalies

In comparison, higher THg levels (up to 9 pg/g dw) have been reported in the Almaden mercury mining district (Ciudad Real, Spain) [51], which can be regarded as the largest geochemical anomaly of mercury on Earth. 

Ferrara, R., B.E. Maserti, and R. Breder. 1991. Mercury in abiotic and biotic compartments of an area affected by a geochemical anomaly (Mt. Amiata, Italy). Water Air Soil Pollut. 56 219-233. 

Two commercial partial extraction techniques improve anomaly contrast in B horizon soil samples compared to aqua regia-ICPMS for Cu and Au. However, whereas the MMIsm and Bio LeachSM Cu profiles are similar, the MMIsm Au signal is much larger than that for Bio LeachSM. Analysis of samples at different depths down the B soil horizon profile indicates that the geochemical response from these methods is depth dependant. 

Levson, V.M. 2001. Regional till geochemical surveys in the Canadian Cordillera sample media, methods, and anomaly evaluation. In McClenaghan, M.B., Bobrowsky, P.T., Hall, G.E.M. Cook, S.J. (eds). Drift Exploration in Glaciated Terrain, Geological Society, Special Publication, 185, 45-68. 

The main conclusion drawn from this study is that hydrocarbon- and fixed gas-based geochemical exploration methods in the Paradox Basin are cost-effective tools for pre-screening large areas to focus subsequent lease acquisition and seismic surveys for oil and gas exploration. Heavy metal anomalies are more difficult to link with the reservoir. 

The rare earth elements (REE) form a group of elements that have coherent geochemical behaviour due to their trivalent charge and similar ionic radii. They can, however, be fractionated from one another as a result of geochemical processes operating under specific physico-chemical conditions. In order to outline general trends within and differences between the individual REE, concentrations are usually normalized to a reference system (e.g. to shale). Deviations of individual elements from the generally smooth trend are referred to as anomalies. 

To track the sources of the geochemical anomalies of heavy metals in suspended matters along the Shun an River basin (one of the main tributary basins of the Anhui section of the Yangtze River basin), a rock survey was conducted on typical ore deposits and outcrops of main strata and geological bodies along the Shun an River basin. The results shown in Table 3 indicate the largest source of Cd in suspended matters on the Shun an River basin is endogenetic deposits, especially Pb-Zn deposits. 

ABSTRACT A geochemical analysis of major, trace and rare earth elements was carried out in beach sands collected from the Northeastern coast of Mexico in order to observe the spatial trends along three different beaches. Results show that major elements patterns along the beaches are controlled by heavy minerals and plutonic and sedimentary input towards the coast. In addition, trace elements tendencies indicate that the beach sands are influenced by the presence of magnetite. Finally, the differences in Eu anomalies indicate a mix of felsic to mafic and intermediate rocks and feldspar weathering. 

There are also natural geochemical anomalies where soils are enriched by cadmium, for example, in the central parts of Sweden. Here the cultivation of crops accumulating cadmium (grains, potato, some grasses) is not recommended. In the coastal marine areas the cadmium mobility in soils is stimulated by its complexation with chlorine. 

Birck JL (2004) An overview of isotopic anomalies in extraterrestrial materials and their nucleosynthetic heritage. Rev Mineral Geochem 55 25-64... 

You et al. (1995) studied bulk samples of fluids incorporated in sediments from ODP Site 808, in the Nankai Trough, southwest of Japan. Pore fluids have somewhat variable isotopic compositions (8 Li = +10 to +21), with a spike of light compositions near the basal decollement. These authors interpreted the decollement zone geochemical anomaly to represent influx of waters with Li derived from leaching of sediments at high temperatures. 

Beukes NJ, Klein C (1992) Models for Iron-formation deposition. In The Proterozoic Biosphere A multidisciplinary study. Schopf JW, Klein C (eds) Cambridge University Press, New York, p 147-151 Birck JL (2004) An overview of isotopic anomalies in extraterreshial materials and their nucleos>mdietic heritage. Rev Mineral Geochem 55 25-64... 

Surface geochemical anomalies in northern Chile product of the extended metallogenesis of buried copper deposits... 

Following my appointment to the Department of Geology in September 1968 rock geochemical studies were undertaken on five Palaeozoic Zn-Pb (Cu) massive sulfide deposits in northern New Brunswick. A total of 115,000 analyses were performed on 13,000 rock samples from the environs of the Heath Steele B and ACD zones, BMS (Brunswick Mining and Smelting) No. 12, Caribou and Key Anacon sulfide deposits. In all cases significant anomalies were defined. 

At the White Lake Cu-Zn sulfide deposit (near Flin Flon, Manitoba) no geochemical signature had been obtained from conventional soil geochemistry. Where the deposit is overlain by 23m of barren rock and 8m of glacial overburden including an upper 1m of impermeable varved clay, a strong characteristic rabbit-ear H anomaly clearly indicates the location of the orebody, as predicted by the electrochemical model (Govett 1976). 

Hamilton, S.M. 1998. Electrochemical mass transport in overburden a new model to account for the formation of selective leach geochemical anomalies in glacial terrain. Journal of Geochemical Exploration, 63, 155-172. 

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