established by earlier studies, such as those of Gast (1969)
and Hedge (1966). There are several reasons for this difference. First, Morgan predicted that plumes should bring
“relatively primordial material” to the shallow mantle, and
hence basalts produced by melting of plumes should be
chemically distinct from the upper mantle. Second, Morgan predicted that plumes should bring “heat” as well, this
too should influence the composition of melts; all other
things being equal, one would expect the extent of melting
in plumes to be greater than beneath mid-ocean ridges.
However, all other things are not always equal, as will
be explained below. Finally, if plumes are buoyant, the
rate of melting and extents of melting should be different
than beneath mid-ocean ridges. Each of these will be considered in the following sections.
Plumes consist of a diverse mix of primitive and
recycled materials
Melting of the mantle preferentially removes elements
that, because of their ionic size or charge, are not easily
accommodated in mantle minerals. These so-called
Hot Spots and Mantle Plumes, Table 1 Mantle plumes and oceanic island chains
Chain
Location
Oceanic crust
age
Youngest
volcanism
Oldest
volcanism
Flux
(Mg s
À1 )
Seismic depth
c
(km)
Large igneous province
Amsterdam–St.
Paul
39
S 77
E 3–5 Ma
~0 Ma
>18 Ma
Rajmahal(?)
Ascension
8
S 14
W
7Ma
2Ma
6–7 Ma
~2,800
No
Austral–Cook
29
S
140
W
40–90 Ma
0 Ma
30 Ma
3.3
a , 3.9
b
~2,800
No
Azores
38
N 28
W 0 Ma
0 Ma
36 Ma
1.1
a
~2,800
Azores Plateau?
Balleny
65
S 167
E 10–20
7
0 ?
7
2.6
Farrar and Tasmania?
8
Bouvet
54
S 3
E
<9.6 Ma
0 Ma
2.5 Ma
0.4
a
>1,900
Karoo?
8
Canary Is
28
N 18
W 155 Ma
0 Ma
68 Ma
1
a
~2,800
No
Cape Verde Is
15
N 24
W 140 Ma
0 Ma
>20 Ma
1.6
a , 0.5
b
~2,800
No
Comoros
11
S 43
E 128 Ma
0 Ma
7.7 Ma
Madagascar?
9
Crozet Is
46
S 50
E 80 Ma
0 Ma
183? Ma
0.5
a
~2,800
Karoo?
10
San Felix–San
Ambrosio
26
S 80
W 20–33 Ma
0 Ma
3.5 Ma
1.6
a , 2.3
b
No
Easter Is
27
S
108
W
4.5 Ma
0.11 Ma
>26 Ma
3.3
a
~2,800
Mid-Pacific mountains
10
Galapagos
1
S 92
W 5 Ma
0 Ma
~100 Ma
1
a
~2,800
The Caribbean
11
Tristan da Cunha–
Gough
37
S 12
W 16 Ma
0 ma
130 Ma
1.7
a , 0.5
b
Etendeka and Parana
Hawaii
19
N155
W 93 Ma
0 Ma
>80 Ma
8.7
a , 6.2
b
!2,350
?
Heard–Kerguelen 49
S 69
E 118 Ma
0 Ma
118 Ma
0.5
a , 0.2
b
~2,800
Kerguelen Plateau,
Rajmahal?
12
Iceland
65
N 10
W 0 Ma
0 Ma
61 Ma
1.4
a
~2,350
North Atlantic Tertiary
Jan Mayen
80
N 9
W 0
0
>0.7 Ma
Siberia?
13
Juan Fernandez Is 33
S 80
W 20–33 Ma
1 Ma
4.2 Ma
1.6
a , 1.7
b
!2,350
No
Louisville
50
S 139 W ~66 Ma
1 Ma
>80 Ma
0.9
a , 3
b
!1,450
Ontong Java
Madeira
33
N 17
W 129 Ma
1 Ma
70 Ma
No
Marion–Prince
Edward
47
S 38
E 0
0 Ma
88 Ma?
Madagascar?
14
The Marquesas
9
S 138
W 63 Ma
0.5 Ma
43 Ma (?)
3.3
a , 4.6
b
Shatsky Rise?
10
Martin
Vaz/Trindade
29
S19
W 90 Ma
1.5 Ma
84 Ma
0.5
a , 0.8
b
Poxoreu?
16
Reunion
21
S 56
E 64 Ma
0
65 Ma
1.9
a , 0.9
b
!1,900
Deccan
Pitcairn–Gambier 25
S
130
W
23 Ma
0
17
8 Ma
3.3
a , 1.7
b
No
Samoa
15
S
168
W
100 Ma
0
24 Ma
1.6
a
~2,800
No
The Society Is
18
S
149
W
45–63 Ma
0
4.3 Ma
3.3
a , 5.8
b
~2,800
No
St. Helena
16
S 6
W
41 Ma
2.5 Ma
19
>81 Ma
0.5
a , 0.3
b
~2,800
No?
Modified from White (2010)
a Plume flux in 10
6 g/s from Sleep (1990)
b
Plume flux in 10
6 g/s from Davies (1988)
c Depth of the s- or p-wave seismic velocity anomaly from Montelli et al. (2006)
HOT SPOTS AND MANTLE PLUMES
319
and Hedge (1966). There are several reasons for this difference. First, Morgan predicted that plumes should bring
“relatively primordial material” to the shallow mantle, and
hence basalts produced by melting of plumes should be
chemically distinct from the upper mantle. Second, Morgan predicted that plumes should bring “heat” as well, this
too should influence the composition of melts; all other
things being equal, one would expect the extent of melting
in plumes to be greater than beneath mid-ocean ridges.
However, all other things are not always equal, as will
be explained below. Finally, if plumes are buoyant, the
rate of melting and extents of melting should be different
than beneath mid-ocean ridges. Each of these will be considered in the following sections.
Plumes consist of a diverse mix of primitive and
recycled materials
Melting of the mantle preferentially removes elements
that, because of their ionic size or charge, are not easily
accommodated in mantle minerals. These so-called
Hot Spots and Mantle Plumes, Table 1 Mantle plumes and oceanic island chains
Chain
Location
Oceanic crust
age
Youngest
volcanism
Oldest
volcanism
Flux
(Mg s
À1 )
Seismic depth
c
(km)
Large igneous province
Amsterdam–St.
Paul
39
S 77
E 3–5 Ma
~0 Ma
>18 Ma
Rajmahal(?)
Ascension
8
S 14
W
7Ma
2Ma
6–7 Ma
~2,800
No
Austral–Cook
29
S
140
W
40–90 Ma
0 Ma
30 Ma
3.3
a , 3.9
b
~2,800
No
Azores
38
N 28
W 0 Ma
0 Ma
36 Ma
1.1
a
~2,800
Azores Plateau?
Balleny
65
S 167
E 10–20
7
0 ?
7
2.6
Farrar and Tasmania?
8
Bouvet
54
S 3
E
<9.6 Ma
0 Ma
2.5 Ma
0.4
a
>1,900
Karoo?
8
Canary Is
28
N 18
W 155 Ma
0 Ma
68 Ma
1
a
~2,800
No
Cape Verde Is
15
N 24
W 140 Ma
0 Ma
>20 Ma
1.6
a , 0.5
b
~2,800
No
Comoros
11
S 43
E 128 Ma
0 Ma
7.7 Ma
Madagascar?
9
Crozet Is
46
S 50
E 80 Ma
0 Ma
183? Ma
0.5
a
~2,800
Karoo?
10
San Felix–San
Ambrosio
26
S 80
W 20–33 Ma
0 Ma
3.5 Ma
1.6
a , 2.3
b
No
Easter Is
27
S
108
W
4.5 Ma
0.11 Ma
>26 Ma
3.3
a
~2,800
Mid-Pacific mountains
10
Galapagos
1
S 92
W 5 Ma
0 Ma
~100 Ma
1
a
~2,800
The Caribbean
11
Tristan da Cunha–
Gough
37
S 12
W 16 Ma
0 ma
130 Ma
1.7
a , 0.5
b
Etendeka and Parana
Hawaii
19
N155
W 93 Ma
0 Ma
>80 Ma
8.7
a , 6.2
b
!2,350
?
Heard–Kerguelen 49
S 69
E 118 Ma
0 Ma
118 Ma
0.5
a , 0.2
b
~2,800
Kerguelen Plateau,
Rajmahal?
12
Iceland
65
N 10
W 0 Ma
0 Ma
61 Ma
1.4
a
~2,350
North Atlantic Tertiary
Jan Mayen
80
N 9
W 0
0
>0.7 Ma
Siberia?
13
Juan Fernandez Is 33
S 80
W 20–33 Ma
1 Ma
4.2 Ma
1.6
a , 1.7
b
!2,350
No
Louisville
50
S 139 W ~66 Ma
1 Ma
>80 Ma
0.9
a , 3
b
!1,450
Ontong Java
Madeira
33
N 17
W 129 Ma
1 Ma
70 Ma
No
Marion–Prince
Edward
47
S 38
E 0
0 Ma
88 Ma?
Madagascar?
14
The Marquesas
9
S 138
W 63 Ma
0.5 Ma
43 Ma (?)
3.3
a , 4.6
b
Shatsky Rise?
10
Martin
Vaz/Trindade
29
S19
W 90 Ma
1.5 Ma
84 Ma
0.5
a , 0.8
b
Poxoreu?
16
Reunion
21
S 56
E 64 Ma
0
65 Ma
1.9
a , 0.9
b
!1,900
Deccan
Pitcairn–Gambier 25
S
130
W
23 Ma
0
17
8 Ma
3.3
a , 1.7
b
No
Samoa
15
S
168
W
100 Ma
0
24 Ma
1.6
a
~2,800
No
The Society Is
18
S
149
W
45–63 Ma
0
4.3 Ma
3.3
a , 5.8
b
~2,800
No
St. Helena
16
S 6
W
41 Ma
2.5 Ma
19
>81 Ma
0.5
a , 0.3
b
~2,800
No?
Modified from White (2010)
a Plume flux in 10
6 g/s from Sleep (1990)
b
Plume flux in 10
6 g/s from Davies (1988)
c Depth of the s- or p-wave seismic velocity anomaly from Montelli et al. (2006)
HOT SPOTS AND MANTLE PLUMES
319