0

1

2

3

4

5

6

7

50 55 60 65 70 75 80

CKD

VF

RA

SR

0

1

2

3

4

5

6

7

50 55 60 65 70 75 80

Tephra

Welded tuffs

(d)(c)

(a)

SiO2

SiO2

(b)

K2O

0

1

2

3

4

5

6

7

50 55 60 65 70 75 80

Complex volcanoes

Calderas

Monogenetic volcanoes

SiO2

K2O

K2O

0

1

2

3

4

5

6

7

50 55 60 65 70 75 80

SiO2

K2O

BBA

A

DR

LK

MK

HK

Holocene

Late Pleistocene

Middle Pleistocene

Early Pleistocene–Pliocene