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Major elements data. Differenciation Magmatic series. 22. 10. Al. O. MgO. 2. 3. 17. 5. 0. 12. 15. 10. FeO*. 10. CaO. 5. 5. 0. 0. 4. 6. 3. Na. O. 2. K. O. 4. 2. 2. 2. 1. 0. 0. 45. 50. 55. 60. 65. 70. 75. 45. 50. 55. 60. 65. 70. 75. SiO. SiO. 2. - PowerPoint PPT Presentation
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Major elements data
•Differenciation•Magmatic series
12
17
22
Al2O3
0
5
10
MgO
0
5
10FeO*
0
2
4
6
Na2O
0
5
10
15
CaO
45 50 55 60 65 70 750
1
2
3
4
K2O
SiO2
45 50 55 60 65 70 75
SiO2
Bivariate Bivariate (x-y) (x-y)
diagramsdiagrams
HarkerHarkerdiagram diagram
forforCraterCraterLakeLake
12
10
8
6
4
2
35 40 45 50 55 60 65
%SiO2
%N
a 2O
+ K
2O
Alkaline
Subalkaline
Alkali vs. Silica diagram for Hawaiian volcanics:Alkali vs. Silica diagram for Hawaiian volcanics:Seems to be two distinct groupings: Seems to be two distinct groupings: alkalinealkaline and and subalkalinesubalkaline
F
A M
Calc-alkaline
T
ho leiitic
AFM diagram:AFM diagram: can further subdivide the subalkaline can further subdivide the subalkaline magma series into a magma series into a tholeiitictholeiitic and a and a calc-alkalinecalc-alkaline series series
Figure 8-14. AFM diagram showing the distinction between selected tholeiitic rocks from Iceland, the Mid-Atlantic Ridge, the Columbia River Basalts, and Hawaii (solid circles) plus the calc-alkaline rocks of the Cascade volcanics (open circles). From Irving and Baragar (1971). After Irvine and Baragar (1971). Can. J. Earth Sci., 8, 523-548.
F
A M
Rhyolite
Dacite
Andesite
Basaltic Andesite
Ferro-Basalt
Basalt
Calc-alkaline
Tholeiitic
Basalt
B-A
A
D
R
Al2O3 K2O
CaO
Al2O3
K2O
CaO
Al2O3
CaO
biotitemuscovitecordieriteandalusitegarnet
pyroxenehornblendebiotite
aegirineriebeckitearfvedsonite
Peraluminous Metaluminous Peralkaline
mol
es
Na2ONa2O
K2O
Na2O
CaO
Figure 18-2. Alumina saturation classes based on the molar proportions of Al2O3/(CaO+Na2O+K2O) (“A/CNK”) after Shand (1927). Common non-quartzo-feldspathic minerals for each type are included. After Clarke (1992). Granitoid Rocks. Chapman Hall.
AlkalineCalc-alkalineTholeitic
Series Alkali content
Fe-Mg Al
Alkaline High Fe-rich Metaluminous to peralkaline
Sub-alkaline
Calc-alkaline
Low to moderate
Mg-rich Metaluminous to per-aluminous
Tholeitic Low Fe-rich Metaluminous
CharacteristicSeries Convergent Divergent Oceanic ContinentalAlkaline yes yes yesTholeiitic yes yes yes yesCalc-alkaline yes
Plate Margin Within Plate
A world-wide survey suggests that there may be A world-wide survey suggests that there may be some important differences between the three seriessome important differences between the three series
After Wilson (1989). Igneous Petrogenesis. Unwin Hyman - Kluwer
