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The Amphibole-Plagioclase Thermometer of Holland & Blundy (1994)
Thermometer A

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This program is used for the recalculation of trivalent iron and the calculation of the occupations/activities in amphiboles. Pressure is calculated according to Johnson & Rutherford (1989). A temperature calculation is then carried out using the hornblende plagioclase thermometer according to Holland & Blundy (1994).
This is the \"Thermometer A\" version. For silica-saturated rocks both thermometers (A and B) may be applied: in silica-undersaturated rocks or magmas thermometer B alone can be applied.
Link to "Thermometer B": >Thermometer B

References

Holland, T., Blundy, J. (1994): Non-ideal interactions in calcic amphiboles and their bearing on amphibole-plagioclase thermometry. – Contr. Mineral. and Petrol. 116, 433–447 (1994).
https://doi.org/10.1007/BF00310910
Johnson, M.C. & Rutherford, M.J., 1989: Experimental calibration of the aluminum-in-hornblende geobarometer with application to Long Valley caldera (California) volcanic rocks. – Geology (1989) 17 (9): 837–841.
See this publication on GeoScienceWorld (GSW), a nonprofit collaborative and comprehensive resource for research and communications in the Earth Sciences.

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The amphibole-plagioclase thermometer A

Recalculation of trivalent iron and calculation of occupancy/activities in amphiboles, as well as temperature calculation with the hornblende-plagioclase thermometer according to Holland & Blundy (1994).

Thermometer A, prevailing conditions: Temp.: 400-900°C; Plg < 0.9; Amph.: Na/A > 0.02; AlVI < 1.8 pfu; Si: 6.0-7.7 pfu
NB: As stated above, thermometer A can only be applied in silica-saturated rocks!

You can enter the values individually in the table or use the input fields. Here you enter the values as rows separated by single spaces (see placeholders; 200 characters max.). Note the order of the elements in the table! Additionally, the sample designation must come first and the sum last. You can use the period or the comma as a decimal separator.

If you want, you can delete the example data in the tables first:

Data input

Oxydes (light blue) and cations (light yellow)
Amphibole 23 O (all Fe as FeO)

Data input

Oxides Cations
SiO2
TiO2
Al2O3
MgO
CaO
MnO
FeO
Na2O
K2O
Total

Plagioclase

Please enter the appropriate values!

XAb: XAn:

Calculation of YAb (Plagioclase) [kJ]

XAb > 0.5
XAb < 0.5

YAb value for temperature calculation:

You can either fill in the value manually or have it filled in automatically. Activate the control field if you want to use the automatic function.

Execute all calculations

Cation calculation

Normalized Fe²⁺/Fe³⁺
Si
Ti
Al
Mg
Ca
Mn
Fetot
Fe2+
Fe3+
Na
K
Total

Pressure calculation after Johnson & Rutherford


Defining the factors fi (Caution: Observe the boundary conditions!)

A

f1
f2
f3
f4
f5

If a value in the left column of group A is > 1, then this value is automatically set to 1 (light blue, right column). I.e. all of the iron is calculated as Fe²⁺.

B

f6
f7
f8
f9
f10

If a value from group B is > 1, the amphibole cannot be calculated stoichiometrically!

Selection of fA and fB

fA fB

Fixing the mean value fav

An average between fA and fB (with fA > fB) is sought. If fB > fA, the analysis fails one of the above conditions for stoichiometry.

fav from fA and fB fav total

Site allocations

cm *
* cm = Cummingtonite substitution
X Si/T1
X Al/T1
X Al/M2
X Na/A
X Na/M4
X Ca/M4
X K/A
X /A

Temperature calculation

Counter
Numerator Bracket
Denominator Bracket
Bracket
ln Bracket
Denominator

Result

T [K]
T [°C]

Table of results

Oxides Cations
SiO2 Si
TiO2 Ti
Al2O3 Al
MgO Mg
CaO Ca
MnO Mn
FeO Fe
Fe2+
Fe3+
Na2O Na
K2O K
Total Total

Plagioclase

XAb XAn

Temperature

T [K] T [°C]

Pressure

Download data

Current date

Enter a title

Sample number, etc.

Download data file (*.csv)