Table 2 Open in new tab Restoring the...

[1] garnet clinopyroxenite (wt. %)

[2] wt. % change in corona

/100 =

[3] compositional change vector for garnet clinopyroxenite

[4] compositional change vector for Opx-bearing felsic granulite

[5] Opx-bearing felsic granulite (wt. %)

[6] hypothetical composition X0 of pristine Ky-granulite (wt. %)

SiO₂

45.91

11.82

5.43

1.56

71.54

73.09

TiO₂

0.34

0.00^*

0.00

0.21

Al₂O₃

16.78

−14.69

−2.46

−0.71

15.03

14.32

FeO^tot

9.24

9.25

0.85

0.25

2.61

2.85

MnO

0.15

−6.28

−0.01

0.00

0.08

MgO

15.24

−14.00

−2.13

−0.61

1.37

0.76

CaO

11.27

−63.50

−7.15

−2.05^*

2.55

0.50^*

Na₂O

0.47

356.69

1.68

0.48

3.63

4.11

K₂O

0.27

65.93

0.18

0.05

2.98

3.03

Table 2

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Restoring the hypothetical composition X0 of the Ky-bearing granulite before its interaction with the garnet clinopyroxenite with TiO₂ as an immobile component

	[1] garnet clinopyroxenite (wt. %)	[2] wt. % change in corona	[3] compositional change vector for garnet clinopyroxenite	[4] compositional change vector for Opx-bearing felsic granulite	[5] Opx-bearing felsic granulite (wt. %)	[6] hypothetical composition X0 of pristine Ky-granulite (wt. %)
SiO₂	45.91	11.82	5.43	1.56	71.54	73.09
TiO₂	0.34	0.00^*	0.00	0.00	0.21	0.21
Al₂O₃	16.78	−14.69	−2.46	−0.71	15.03	14.32
FeO^tot	9.24	9.25	0.85	0.25	2.61	2.85
MnO	0.15	−6.28	−0.01	0.00	0.08	0.08
MgO	15.24	−14.00	−2.13	−0.61	1.37	0.76
CaO	11.27	−63.50	−7.15	−2.05^*	2.55	0.50^*
Na₂O	0.47	356.69	1.68	0.48	3.63	4.11
K₂O	0.27	65.93	0.18	0.05	2.98	3.03

	[1] garnet clinopyroxenite (wt. %)	[2] wt. % change in corona	[3] compositional change vector for garnet clinopyroxenite	[4] compositional change vector for Opx-bearing felsic granulite	[5] Opx-bearing felsic granulite (wt. %)	[6] hypothetical composition X0 of pristine Ky-granulite (wt. %)
SiO₂	45.91	11.82	5.43	1.56	71.54	73.09
TiO₂	0.34	0.00^*	0.00	0.00	0.21	0.21
Al₂O₃	16.78	−14.69	−2.46	−0.71	15.03	14.32
FeO^tot	9.24	9.25	0.85	0.25	2.61	2.85
MnO	0.15	−6.28	−0.01	0.00	0.08	0.08
MgO	15.24	−14.00	−2.13	−0.61	1.37	0.76
CaO	11.27	−63.50	−7.15	−2.05^*	2.55	0.50^*
Na₂O	0.47	356.69	1.68	0.48	3.63	4.11
K₂O	0.27	65.93	0.18	0.05	2.98	3.03

^*assumed.

As a basis served the compositional change vector [3] obtained by multiplying the garnet clinopyroxenite composition [1] with wt. % change in its corona [2] (inferred from the concentration ratio diagram; Fig. 11) and dividing by 100.

These elemental losses/gains had to be compensated by the Opx-bearing felsic granulite host. Considering that the degree of the change is limited by the availability of CaO (a component with the most dramatic depletion that would be exhausted first), the CaO content in composition X0 [6] was set to an arbitrarily low value of 0.5 wt. %. This means that the CaO value changes by −2.05 [4]. The remaining items of the compositional change vector [4] were obtained from [3] multiplied by the factor of 2.05/7.15. Applying the vector [4] to the actual Opx-bearing felsic granulite composition [5], we obtained the hypothetical pristine felsic granulite composition X0 [6].

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