**5.1 Andesite-dacite-rhyolite association**

The association rocks form a continuous series from andesites to rhyolites by SiO2 contents (SiO2 > 60%) (**Table 2**), and the ratio (Na2O+K2O)-SiO2 [21] are the rocks of normal alkalinity (**Figure 5**) (some rocks – mid alkaline) in the diagram K2O-SiO2 [22] most of the samples falls within the high K calc-alkaline series, the diagram FeO \*/ MgO-SiO2 composition points are located in the field calc-alkaline series.


### *Late Cenozoic Collisional Volcanism in the Central Part of the Lesser Caucasus (Azerbaijan) DOI: http://dx.doi.org/10.5772/intechopen.93334*

**5. Petrochemical features of the Late Cenozoic volcanic rocks**

*Updates in Volcanology – Transdisciplinary Nature of Volcano Science*

The association rocks form a continuous series from andesites to rhyolites by SiO2 contents (SiO2 > 60%) (**Table 2**), and the ratio (Na2O+K2O)-SiO2 [21] are the rocks of normal alkalinity (**Figure 5**) (some rocks – mid alkaline) in the diagram K2O-SiO2 [22] most of the samples falls within the high K calc-alkaline series, the diagram FeO \*/ MgO-SiO2 composition points are located in the field calc-alkaline

*Photomicrographs of the thin sections of rocks of the trachybasalt-trachyandesite association. Trachyandesite (one can see a glomeroporphyritic cluster of clinopyroxenes and opacitized hornblende, plagioclase, and clinopyroxene phenocrysts), 80, with an analyzer; moderately alkaline olivine basalt with olivine, clinopyroxene, and plagioclase phenocsrysts, 80, with an analyzer; crushed olivine in trachybasalt, 80, with*

**5.1 Andesite-dacite-rhyolite association**

*an analyzer; trachydolerite, 80, with an analyzer.*

series.

**50**

**Figure 4.**


**17**

**53**

MgO

CaO

Na O

2

K O

2

P O2 5

LOI

Total

Rb

Li Sr Ba Cr

V Ni Co Zr Nb

Ta Hf Th

U La

62

 76

 77

 77

 59

 66

 69

 52

 96

 80

 60

 60

 70

 59

 67

 48

 72

4

 4

 4

 3

 4

 4

 n.d.

 4

 3

 4

 3.6

 6.3

 4

 4

 4

 4

 12.2

4.9

 5.2

 7.4

 8.1

 6.1

 5.3

 n.d.

 5.6

 6.4

 6.5

 6.3

 6.5

 8.8

 5.6

 9.5

 9.7

 3.2

5.1

 4.5

 4.6

 5.2

 4.2

 4.7

 n.d.

 4.4

 4.8

 5

 4.8

 4.5

 5.3

 4.7

 4.7

 4.3

 6.6

0.96

 1.2

 1.7

 1.5

 0.8

 0.99

 n.d.

 1

 1.4

 1.3

 0.81

 0.87

 1

 0.98

 1.4

 0.88

 1.43

20

 28

 27

 23

 10

 21

 18

 19

 23

 22

 18

 13

 18

 21

 23

 15

 33

250

 200

 220

 250

 180

 210

 250

 190

 250

 250

 190

 180

 220

 207

 200

 160

 303

24

 26

 50

 45

 19

 50

 22

 45

 55

 35

 45

 16

 20

 40

 19

 13

 11

100

 43

 64

 45

 46

 48

 34

 65

 40

 39

 50

 54

 50

 33

 29

 31

 13.5

260

 140

 200

 150

 200

 200

 150

 170

 240

 150

 80

 130

 100

 140

 140

 110

 70

450

 170

 220

 n.d.

 157

 200

 224

 280

 n.d.

 n.d.

 160

 188

 100

 n.d.

 n.d.

 n.d.

 140

990

 1300

 1170

 1170

 1140

 1000

 1080

 680

 1100

 1770

 830

 1060

 900

 900

 1016

 930

 1100

1700

 2635

 2550

 1900

 1615

 1615

 1445

 1020

 1275

 1785

 1360

 1275

 1615

 1647

 1360

 790

 1356

*Late Cenozoic Collisional Volcanism in the Central Part of the Lesser Caucasus (Azerbaijan)*

9

 14

 9

 13

 12

 12

 13

 14

 14

 13

 10

 12

 16

 14

 17

 15

 20

34

 60

 31

 60

 37

 36

 42

 54

 70

 43

 55

 49

 66

 40

 56

 48

 70

 98

 99.05

 98.14

 98.42

 98.23

 98.14

 98.47

 99.07

 98.8

 100.7

 98.32

 98.68

 99.72

 100.12

 101.1

 100

 100.19

 1.79

 0.61

 1.9

 1.1

 0.14

 0.35

 0.85

 0.41

 0.19

 0.44

 0.64

 0.4

 0.35

 0.27

 0.2

 1.15

 0.01

1.13

 1.31

 1.04

 0.93

 0.82

 0.83

 0.94

 0.58

 0.75

 0.94

 0.57

 0.68

 0.79

 0.68

 0.76

 0.44

 0.35

*DOI: http://dx.doi.org/10.5772/intechopen.93334*

 1.73

 2.92

 2.48

 3.16

 2.8

 2.77

 2.17

 2.6

 2.96

 3.25

 3.01

 2.8

 3.11

 2.87

 3.46

 2.89

 4

 4.18

 4.14

 3.22

 4.39

 5.03

 4.27

 0.7

 4.22

 4.78

 4.53

 3.85

 4

 4.38

 4.53

 4.65

 4.53

 5.5

 9.19

 8.58

 9.1

 7

 7.17

 6.71

 6.88

 6.24

 6.66

 6.8

 6.25

 6.24

 5.61

 6.09

 5.82

 6.12

 2.2

 6.81

 4.42

 5.27

 3.65

 3.81

 4.12

 3.76

 4.66

 3.84

 3.37

 3.18

 3.23

 2.67

 2.29

 2.79

 2.77

 1.1

 **18**

 **19**

 **20**

 **21**

 **22**

 **23**

 **24**

 **25**

 **26**

 **27**

 **28**

 **29**

 **30**

 **31**

 **32**


### *Late Cenozoic Collisional Volcanism in the Central Part of the Lesser Caucasus (Azerbaijan) DOI: http://dx.doi.org/10.5772/intechopen.93334*

**1**

**52**

Zr Nb

Ta Hf Th

U La Ce Sm Eu Tb Yb Lu

Y

36

**17**

Elements

SiO2 TiO2

Al

Fe

O2 3

FeO

MnO

 0.13

 0.11

 0.12

 0.12

 0.1

 0.13

 0.1

 0.12

 0.12

 0.12

 0.05

 0.09

 0.11

 0.11

 0.1

 0.13

 0.05

 4.46

 1.01

 0.72

 0.3

 0.57

 1.65

 2.59

 0.43

 2.17

 2.46

 1.87

 0.87

 0.5

 3.09

 1.3

 1.88

 3

3.55

 6.11

 7.16

 7.04

 6.11

 5.66

 4.54

 6.59

 5.02

 5.79

 4.09

 4.8

 4.88

 4.62

 4.95

 3.79

 n.d.

O2 3

15.53

 16.64

 16.27

 16.46

 17.39

 17.46

 16.38

 17.13

 16.82

 17.49

 16.41

 16.23

 16.57

 17.25

 16.55

 17.7

 15.7

1.45

 1.36

 1.44

 1.3

 0.97

 1.14

 1.14

 1.08

 1.18

 1.5

 0.79

 0.82

 0.8

 1.24

 1.24

 0.75

 0.48

48.05

 51.84

 49.42

 52.97

 53.32

 53.05

 54.92

 55.67

 54.31

 54.01

 57.66

 58.52

 59.85

 57.08

 59.28

 57.85

 67.8

 134

 21

 57

 208

 53

 87

 109

 120

 167

 174

 13

 25

 33

 143

 160

 185

 73/P

 **18**

 **19**

 **20**

 **21**

 **22**

 **23**

 **24**

 **25**

 **26**

 **27**

 **28**

 **29**

 **30**

 **31**

 **32**

 **33**

 16

 11

 10

 11

 16

 n.d.

 11

 29

 10

 10

11

 11

 31

 30

 34

0.19

 0.18

 0.2

 0.2

 0.69

 0.23

 0.17

 0.17

 0.18

 0.32

 0.42

 0.24

 0.22

 0.42

 0.39

 0.33

1.2

 1.3

 1.4

 1.5

 3.6

 1.8

 1.3

 1.3

 1.4

 2.3

 2.3

 1.3

 1.32

 2.4

 2.7

 2.4

0.67

 0.43

 0.56

 0.58

 1.1

 0.9

 0.44

 0.42

 0.57

 0.6

 0.68

 0.15

 0.13

 0.88

 1.5

 1.3

1.2

 1

 1.2

 1

 1.6

 1.6

 1.1

 0.95

 0.79

 0.2

 0.65

 0.1

 0.16

 1.7

 2.5

 2.5

4.2

 3.6

 3.9

 4.2

 7.5

 5.1

 3.6

 4.4

 5

 3

 2.8

 2.42

 2.51

 5.3

 9.5

 9.8

88

 73

 77

 76

 57

 91

 87

 74

 78

 60

 59

 41.4

 53

 81

 130

 130

*Updates in Volcanology – Transdisciplinary Nature of Volcano Science*

45

 37

 43

 36

 23

 47

 47

 38

 47

 33.5

 36

 23.5

 30.7

 40

 65

 63

2.7

 4.7

 5.7

 4.4

 4

 4

 5.4

 3.3

 14

 9.3

 12

 12.1

 10.2

 4

 4

 4

11

 11

 9.3

 10

 n.d.

 10

 18

 16

 5.2

 25

 31

 37.3

 34.5

 3.2

 2.6

 2.6

4.8

 4

 3.6

 3.3

 3.8

 4.3

 4.7

 4.2

 6

 n.d.

 n.d.

 3.87

 3.51

 4.7

 4.6

 5.2

0.84

 0.82

 0.72

 0.94

 0.46

 0.77

 1.4

 1.1

 1.2

 n.d.

 n.d.

 3.11

 2.71

 0.85

 0.92

 0.92

12

 10

 11

 10

 8

 11

 14

 14

 17

 15

 10

37

 34

 n.d.

 20

 18

178

 150

 160

 150

 130

 160

 170

 150

 240

 100

 80

 83

 86

 n.d.

 230

 240

 **2**

 **3**

 **4**

 **5**

 **6**

 **7**

 **8**

 **9**

 **10**

 **11**

**12**

 **13**

 **14**

 **15**


**Table 2.** *Major (wt %) and trace-element (ppm) composition of a representative rocks of the Late Cenozoic associations in the Lesser Caucasus (Azerbaijan).*

The rocks of this association are characterized by different contents of major elements. In volcanic rocks with increasing SiO2 content decreases TiO2, Al2O3,

*Late Cenozoic Collisional Volcanism in the Central Part of the Lesser Caucasus (Azerbaijan)*

clinopyroxene, plagioclase, and possibly apatite. Weak rates increased content of K2O. Na2O is distributed evenly, but also an increase in the number of its slower rate. The reason for this pattern may be a potassium feldspar in the more acidic

Rocks associations, in contrast to the previous rock associations, are characterized by ultra-structure and high alkalinity. There is approximately equal ratio of Na2O and K2O and low contents of CaO, MgO, and FeO (**Table 2**). In the normative composition of the rocks are calculated high content of salic components of quartz,

For silica rock associations form a continuous series from basalts to andesites (**Table 2**) and belong to the mildly alkaline series (**Figure 5**). In the diagram K2O-SiO2 composition points fall in the region high-K calc-alkaline and shoshonite series. In rock associations in the range of "trachybasalt-basaltic trachyandesite" with increasing silica content of TiO2, MgO, Fe2O3, CaO, and P2O5 is reduced to a large extent, the contents of the same Al2O3, Na2O decreases the slow pace. In the transition to trachyandesites content of these elements varies in a narrow range. The maximum content of MgO is observed in trachybasalts and alkaline olivine basalts and varies from 3.97 to 6.81% (**Table 2**), and the coefficient of Mg6¼ (M) from 56 to 71. In subsequent decrease differentiates the content of MgO and "M." In the normative part of some mildly alkali olivine basalts and trachybasalts calculated normative nepheline and olivine, and in more acidic differentiates calculated hypersthene and quartz. Normative and mineral composition reflects the

*Total alkali vs. -SiO2 (TAS) classification diagrams [21] of Late Cenozoic volcanic associations of the Lesser Caucasus. In. 1 – andesite-dacite-rhyolite; 2 – rhyolitic association; 3 – trachybasalt-trachyandesite*

Fe2O3, MgO, CaO, and P2O5, due to fractionation of titanomagnetite,

varieties of rocks.

**5.2 Rhyolitic association**

*DOI: http://dx.doi.org/10.5772/intechopen.93334*

feldspar, and corundum.

**Figure 5.**

*associations.*

**55**

**5.3 Trachybasalt-trachyandesite association**

*Late Cenozoic Collisional Volcanism in the Central Part of the Lesser Caucasus (Azerbaijan) DOI: http://dx.doi.org/10.5772/intechopen.93334*

The rocks of this association are characterized by different contents of major elements. In volcanic rocks with increasing SiO2 content decreases TiO2, Al2O3, Fe2O3, MgO, CaO, and P2O5, due to fractionation of titanomagnetite, clinopyroxene, plagioclase, and possibly apatite. Weak rates increased content of K2O. Na2O is distributed evenly, but also an increase in the number of its slower rate. The reason for this pattern may be a potassium feldspar in the more acidic varieties of rocks.

## **5.2 Rhyolitic association**

Rocks associations, in contrast to the previous rock associations, are characterized by ultra-structure and high alkalinity. There is approximately equal ratio of Na2O and K2O and low contents of CaO, MgO, and FeO (**Table 2**). In the normative composition of the rocks are calculated high content of salic components of quartz, feldspar, and corundum.

### **5.3 Trachybasalt-trachyandesite association**

For silica rock associations form a continuous series from basalts to andesites (**Table 2**) and belong to the mildly alkaline series (**Figure 5**). In the diagram K2O-SiO2 composition points fall in the region high-K calc-alkaline and shoshonite series. In rock associations in the range of "trachybasalt-basaltic trachyandesite" with increasing silica content of TiO2, MgO, Fe2O3, CaO, and P2O5 is reduced to a large extent, the contents of the same Al2O3, Na2O decreases the slow pace. In the transition to trachyandesites content of these elements varies in a narrow range. The maximum content of MgO is observed in trachybasalts and alkaline olivine basalts and varies from 3.97 to 6.81% (**Table 2**), and the coefficient of Mg6¼ (M) from 56 to 71. In subsequent decrease differentiates the content of MgO and "M."

In the normative part of some mildly alkali olivine basalts and trachybasalts calculated normative nepheline and olivine, and in more acidic differentiates calculated hypersthene and quartz. Normative and mineral composition reflects the

### **Figure 5.**

*Total alkali vs. -SiO2 (TAS) classification diagrams [21] of Late Cenozoic volcanic associations of the Lesser Caucasus. In. 1 – andesite-dacite-rhyolite; 2 – rhyolitic association; 3 – trachybasalt-trachyandesite associations.*

**17**

**54**

Ce Sm Eu Tb Yb Lu

Y *1–9 –* **Table 2.**

*Major (wt %) and* 

*trace-element*

 *(ppm) composition*

 *of a* 

*representative*

 *rocks of the Late Cenozoic associations*

 *in the Lesser Caucasus* 

*(Azerbaijan).*

*andesite-dacite-rhyolite;*

 *10–14 – rhyolitic association;*

29

 16

 23

 23

 20

 *15–33 –*

 24

 21 *trachybasalt-trachyandesite*

 *associations.*

 19

 27

 25

 14

 15

 19

 16

 19

 15

 10

*Updates in Volcanology – Transdisciplinary Nature of Volcano Science*

0.31

 0.22

 0.34

 0.34

 0.25

 0.28

 0.22

 0.39

 0.31

 0.27

 0.31

 0.3

 0.26

 0.25

 0.24

 0.24

 0.25

2.2

 1.8

 1.9

 2.3

 1.8

 2.1

 2

 2

 2.2

 2

 1.8

 1.9

 2

 2.2

 2.1

 1.3

 2.1

1.1

 1

 1.3

 1.3

 1

 1.4

 1.1

 0.9

 1.1

 0.95

 1.1

 0.94

 0.85

 1.8

 1.2

 0.59

 1.12

2.4

 2.5

 2.8

 2.5

 1.6

 1.8

 2

 1.7

 2.2

 2.7

 1.6

 1.7

 1.7

 2

 2

 1.4

 1.5

9.1

 10

 11

 9.5

 6.3

 7.4

 7.4

 5.9

 7.4

 9.8

 5.7

 5.3

 5.8

 7.2

 8.6

 5.7

 6

120

 150

 160

 160

 120

 130

 130

 98

 120

 160

 120

 120

 120

 120

 140

 88

 115

 **18**

 **19**

 **20**

 **21**

 **22**

 **23**

 **24**

 **25**

 **26**

 **27**

 **28**

 **29**

 **30**

 **31**

 **32**

characteristic feature of the association: transition nepheline-normative, olivine containing mildly alkaline rocks to hypersthene-normative, and sometimes quartzbearing alkaline rocks.
