<p>There's no simple answer to this. The elemental ratios are a function of proximity to the ocean (Na, Cl, Br, I, etc), relative abundance and mode of weathering of feldspar, rate of weathering, rock Mg-Fe ratio and redox state (especially in relation to iron), the degree of rock mineralization (SO4, Cl, F), rock heterogeneity, and how close the rock-water system is to thermodynamic equilibrium.
There are many good books on the subject, of which my long-standing favorite is John Hem's classic US Geological Survey Water Supply Paper 2254, <em>Study and Interpretation of the Chemical Characteristics of Natural Water</em>, 3rd Edition, <a href="http://pubs.usgs.gov/wsp/wsp2254/pdf/wsp2254a.pdf" rel="nofollow">available online as a PDF</a>.</p>

CC BY-SA 3.0
2016-04-25T18:40:09.960Z
2016-05-01T23:35:02.200Z
2016-05-01T23:35:02.200Z
Gordon Stanger
<p>I have chemical analysis of one catchment which can be considered more or less homogeneous and also stream water analysis, I would like to know how elemental ratios (to Na for example) are related both in the geology and in the water. The rocks are mostly andesites. Can I expect the ratios to be similar, and based on your expertise can you recommend a methodology to relate both variables? </p>

<geology><geochemistry><water>
Elemental ratios in rocks and stream water
Marlon Calispa
# Elemental ratios in rocks and stream water

(Asked by: username_0 on 2016-04-25)

I have chemical analysis of one catchment which can be considered more or less homogeneous and also stream water analysis, I would like to know how elemental ratios (to Na for example) are related both in the geology and in the water. The rocks are mostly andesites. Can I expect the ratios to be similar, and based on your expertise can you recommend a methodology to relate both variables?

**Tags:** geology, geochemistry, water


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## 1 answers

### Answer by username_1 on 2016-04-25. Score: 4 | Accepted answer

There's no simple answer to this. The elemental ratios are a function of proximity to the ocean (Na, Cl, Br, I, etc), relative abundance and mode of weathering of feldspar, rate of weathering, rock Mg-Fe ratio and redox state (especially in relation to iron), the degree of rock mineralization (SO4, Cl, F), rock heterogeneity, and how close the rock-water system is to thermodynamic equilibrium.
There are many good books on the subject, of which my long-standing favorite is John Hem's classic US Geological Survey Water Supply Paper 2254, *Study and Interpretation of the Chemical Characteristics of Natural Water*, 3rd Edition, [available online as a PDF](http://pubs.usgs.gov/wsp/wsp2254/pdf/wsp2254a.pdf).


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