Generally , the CIA is interpreted as a measure of the extent of the conversion of feldspar to clays. It is computed using molar proportions as below:
CIA = Al2O3 / (Al2O3 + CaO* + Na2O + K2O) ×100
CaO* is the amount of CaO incorporated in the silicate fraction of the rock.
How CaO* is calculated?
These references may help you
The applicability of the Chemical Index of Alteration as a paleoclimatic indicator: An example from the Permian of the Paraná Basin, Brazil--Karin Goldberga, , , Munir Humayun
Palaeogeography, Palaeoclimatology, Palaeoecology, Volume 293, Issues 1–2, 1 July 2010, Pages 175–183
Chapter 6 A review of the Chemical Index of Alteration (CIA) and its application to the study of Neoproterozoic glacial deposits and climate transitions--Heinrich Bahlburg1,* and Nicole Dobrzinski
Geological Society, London, Memoirs 2011, v. 36, p. 81-92
Chemical indices (CIA and WIP) as proxies for integrated chemical weathering in
China: Inferences from analysis of fluvial sediments--Jingqing Shao, Shouye Yang⁎, Chao Li
Sedimentary Geology 265-266 (2012) 110–120
Hello,
I think you have to do a detailed mineralogical analysis (e.g. by XRD). You need to measure the amount of carbonate minerals (calcite, dolomite etc.). Then you can calculate their relative contribution to the total CaO amount measured by e.g. ICP-MS. The difference between the total CaO and the "Carboante"-CaO should be your CaO in silicates. But you have to make sure that there are not more other minerals which incorporate Ca in their crystal structure.
Best regards
Thanks to Asoori Latha and Christian Günther for inputs. Dr. Asit
Dear Dr. Batabyal,
After 40 years in the business, I know that it is often an uphill battle to persuade geoscientists to follow a simple “chain of command” in geoscientific studies:
1. (Field) geology (good mapping and sampling)
2. Mineralogy from the hand specimen to the nanoscale
3. Chemistry from the simple method, e.g., from the XRF to the mass spectrometry of isotopes.
Geophysics may take the same level in the hierarchy as No. 1 and 2.
Each case history has its own rules according to which you have to use and adjust indices like those or even come to the conclusion and decide to omit them because of enough information already collected in one of the predecessor investigations or after some forward modeling find out that it is not worth the trouble to use this or that method or any index.
Too many put the cart before the horse because they think it speeds up the process and they will make faster progress. But this is certainly not a realistic approach and may only help for a while to ride the “paper tiger”.
Sorry for that piece of advice from a “vintage geologist”
With kind regards
H.G.Dill
i think these references may help you :
Is chemical index of alteration (CIA) a reliable proxy for chemical weathering in global drainage basins? Article Is chemical index of alteration (CIA) a reliable proxy for c...
Determination of the geochemical weathering indices and trace elements content of new volcanic ash deposits from Mt. Talang (West Sumatra) Indonesia https://biblio.ugent.be/publication/1087716
A Study on the Chemical Index of Alteration of Igneous Rocks
http://www.koreascience.or.kr/article/ArticleFullRecord.jsp?cn=GJBGC4_2012_v28n5_41
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