pyrolite.geochem.alteration

Functions for calcuating indexes of chemical alteration.

pyrolite.geochem.alteration.CIA(df: DataFrame)

Chemical Index of Alteration (molecular) [1]

Parameters:

df (pandas.DataFrame) – DataFrame to calculate index from.

Returns:

Alteration index series.

Return type:

pandas.Series

References

[1]

Nesbitt HW, Young GM (1984). Prediction of some weathering trends of plutonic and volcanic rocks based on thermodynamic and kinetic considerations. Geochimica et Cosmochimica Acta 48:1523–1534. doi: 10.1016/0016-7037(84)90408-3

pyrolite.geochem.alteration.CIW(df: DataFrame)

Chemical Index of Weathering (molecular) [2]

Parameters:

df (pandas.DataFrame) – DataFrame to calculate index from.

Returns:

Alteration index series.

Return type:

pandas.Series

References

[2]

Harnois L (1988). The CIW index: A new chemical index of weathering. Sedimentary Geology 55:319–322. doi: 10.1016/0037-0738(88)90137-6

pyrolite.geochem.alteration.PIA(df: DataFrame)

Plagioclase Index of Alteration (molecular) [3]

Parameters:

df (pandas.DataFrame) – DataFrame to calculate index from.

Returns:

Alteration index series.

Return type:

pandas.Series

References

[3]

Fedo CM, Nesbitt HW, Young GM (1995). Unraveling the effects of potassium metasomatism in sedimentary rocks and paleosols, with implications for paleoweathering conditions and provenance. Geology 23:921–924. doi: `10.1130/0091-7613(1995)023<0921:UTEOPM>2.3.CO;2 <https://dx.doi.org/10.1130/0091-7613(1995)023<0921:UTEOPM>2.3.CO;2>`__

pyrolite.geochem.alteration.SAR(df: DataFrame)

Silica-Alumina Ratio (molecular)

Parameters:

df (pandas.DataFrame) – DataFrame to calculate index from.

Returns:

Alteration index series.

Return type:

pandas.Series

pyrolite.geochem.alteration.SiTiIndex(df: DataFrame)

Silica-Titania Index (molecular) [4]

Parameters:

df (pandas.DataFrame) – DataFrame to calculate index from.

Returns:

Alteration index series.

Return type:

pandas.Series

References

[4]

Jayawardena U de S, Izawa E (1994). A new chemical index of weathering for metamorphic silicate rocks in tropical regions: A study from Sri Lanka. Engineering Geology 36:303–310. doi: 10.1016/0013-7952(94)90011-6

pyrolite.geochem.alteration.WIP(df: DataFrame)

Weathering Index of Parker (molecular) [5]

Parameters:

df (pandas.DataFrame) – DataFrame to calculate index from.

Returns:

Alteration index series.

Return type:

pandas.Series

References

[5]

Parker A (1970). An Index of Weathering for Silicate Rocks. Geological Magazine 107:501–504. doi: 10.1017/S0016756800058581

pyrolite.geochem.alteration.IshikawaAltIndex(df: DataFrame)

Alteration Index of Ishikawa (wt%) [6]

Parameters:

df (pandas.DataFrame) – DataFrame to calculate index from.

Returns:

Alteration index series.

Return type:

pandas.Series

References

[6]

Ishikawa Y, Sawaguchi T, Iwaya S, Horiuchi M (1976). Delineation of prospecting targets for Kuroko deposits based on modes of volcanism of underlying dacite and alteration halos. Mining Geology 27:106-117.

pyrolite.geochem.alteration.CCPI(df: DataFrame)

Chlorite-carbonate-pyrite index of Large et al. (wt%) [7].

Parameters:

df (pandas.DataFrame) – DataFrame to calculate index from.

Returns:

Alteration index series.

Return type:

pandas.Series

Notes

Here FeO is taken as total iron (FeO+Fe2O3).

References

[7]

Large RR, Gemmell, JB, Paulick, H (2001). The alteration box plot: A simple approach to understanding the relationship between alteration mineralogy and lithogeochemistry associated with volcanic-hosted massive sulfide deposits. Economic Geology 96:957-971. doi:10.2113/gsecongeo.96.5.957