Chapter 9
Hotspots
Abstract Hotspots are regions of the lithosphere that are fed by the melting of a
hot mantle plume, giving rise to volcanic activity on the Earth’s surface. The
source of hot mantle material (a ‘‘plume’’) could have originated in the lower
mantle, at the boundary of the molten Earth’s core at 2900 km depth. The mantle’s
thermal flow ceases when attaining the colder and more rigid lithosphere boundary, less than 100 km deep. The rising of hot mantle plumes contributes to partial
melting and to a thinning of the rigid lithosphere’s plates. Some volcanic edifices
created during hotspot volcanism are formed on top of spreading ridges such as the
islands of Iceland and Jan-Mayen in the Atlantic or Amsterdam Island in
the Indian Ocean. Many other hotspot volcanoes occur in the intra-plate regions of
the world’s oceanic basins and form tall submarine or subaerial edifices rising
more than 4000 m from the seafloor.
Introduction
The movement of the lithospheric plates over ‘‘fixed’’ thermal anomalies located
in the upper mantle will form many linear volcanic seamounts and islands (Wilson
1963; Morgan 1972). Burke and Wilson (1976) identified up to 122 hotspots,
which have been active during the past 10 Ma, as well as 52 hotspots located near
the ridge axis. Crough (1983) detected about 140 hotspots located in continental
and oceanic areas (Fig. 9.1). It is likely this number is no longer valid because,
when looking at the World’s gravity anomaly (Smith and Sandwell 1997), it
appears that many unexplored intraplate structural highs may also be the result of
hotspots.
The excess topography for volcanic constructions is proportional to the amount
of melt delivered to the surface, and the amount of melt delivered is often considered to be greatest above hotspots. However, based on satellite altimetry data as
well as on conventional bathymetry (depth sounding), it is difficult to distinguish
between structures caused by hotspot volcanism from those inherited from crustal
R. Hekinian, Sea Floor Exploration, Springer Oceanography,
DOI: 10.1007/978-3-319-03203-0_9,
Ó Springer International Publishing Switzerland 2014
301
Hotspots
Abstract Hotspots are regions of the lithosphere that are fed by the melting of a
hot mantle plume, giving rise to volcanic activity on the Earth’s surface. The
source of hot mantle material (a ‘‘plume’’) could have originated in the lower
mantle, at the boundary of the molten Earth’s core at 2900 km depth. The mantle’s
thermal flow ceases when attaining the colder and more rigid lithosphere boundary, less than 100 km deep. The rising of hot mantle plumes contributes to partial
melting and to a thinning of the rigid lithosphere’s plates. Some volcanic edifices
created during hotspot volcanism are formed on top of spreading ridges such as the
islands of Iceland and Jan-Mayen in the Atlantic or Amsterdam Island in
the Indian Ocean. Many other hotspot volcanoes occur in the intra-plate regions of
the world’s oceanic basins and form tall submarine or subaerial edifices rising
more than 4000 m from the seafloor.
Introduction
The movement of the lithospheric plates over ‘‘fixed’’ thermal anomalies located
in the upper mantle will form many linear volcanic seamounts and islands (Wilson
1963; Morgan 1972). Burke and Wilson (1976) identified up to 122 hotspots,
which have been active during the past 10 Ma, as well as 52 hotspots located near
the ridge axis. Crough (1983) detected about 140 hotspots located in continental
and oceanic areas (Fig. 9.1). It is likely this number is no longer valid because,
when looking at the World’s gravity anomaly (Smith and Sandwell 1997), it
appears that many unexplored intraplate structural highs may also be the result of
hotspots.
The excess topography for volcanic constructions is proportional to the amount
of melt delivered to the surface, and the amount of melt delivered is often considered to be greatest above hotspots. However, based on satellite altimetry data as
well as on conventional bathymetry (depth sounding), it is difficult to distinguish
between structures caused by hotspot volcanism from those inherited from crustal
R. Hekinian, Sea Floor Exploration, Springer Oceanography,
DOI: 10.1007/978-3-319-03203-0_9,
Ó Springer International Publishing Switzerland 2014
301