volcanic ridges and volcanic cones observed on off-axis volcanoes forming the
linear volcanic ridges (Fig. 7.33).
2. An alternative hypothesis implies that hotspot-ridge interaction is mainly the
result of magma flow differentiation during the hot plume-derived melting
process (Niu et al. 1999; Hekinian 2004). In this case, the plume that gives rise
to hotspot volcanism is the main source for driving volcanic activity on the
ridge axis. Niu et al. (1999) suggested that much of the material needed to
create ocean crust and oceanic lithosphere must be supplied by lateral sublithospheric flow through the Low Velocity Zone (LVZ) at 670 km depth.
When this mantle material reaches the base of the lithosphere (70–100 km
depth), it flows laterally following the plate motion and the path of least
resistance, such as faults and fissures. When the plates diverge during spreading
at the ridge axis, it will drain the magma through the fissured and fractured
lithosphere. The ridge-ward flowing and melting plume material is progressively depleted in its enriched components as it approaches the ridge.
According to this hypothesis, the commonly interpreted geochemical ‘‘mixing’’
between compositionally distinct enriched-plume material and a depleted ‘‘MORB
source’’ in the context of a plume-ridge interaction is misleading. Hence, the
apparent ‘‘mixing relationship’’ observed in geochemistry could in fact be the
consequence of a partial melting of two different mantle sources.
References
Auzende J-M, Sinton J, Ballu V, Batiza R, Bideau D, Fouquet, Y, Cormier M-H, Geistdoerfer P,
Lagabrielle Y, and Piera Spadea P (1994) NAUDUR explorers discover recent volcanic
activity along the East Pacific Rise. Eos Trans Am Geophys Union 75(51):601, 604–605
Avedik F, Geli L (1987) Single-channel seismic reflection data from the East Pacific Rise axis
between latitude 11°50
0 and 12°54
0 N. Geology 15:857–860
Bäcker H, Lange H, Marchig V (1985) Hydrothermal activity and sulfide formation in axial
valley of the East Pacific Rise crest between 18°S and 22°S. Earth, Planet Sci Lett 72:9–22
Ballard RD (1983) Exploring our living Planet. National Geographical Society Washington D.C .,
p 366
Ballard RD, McConnell M (1995) Explorations: a life of underwater adventure. Hyperion, New
York, p 407
Barberi F, Varet J (1970a) The Erta Ale volcanic range (Danakil depression northern Afar,
Ethiopia). Bull Volcanol tome XXXIV, Fascicule 4:848–891
Batiza R (1981) Quantitative data on the abundance and distribution of seamounts in the Pacific
Ocean, McDonnell Center for Space Sciences Publ. MCP 498, p 23
Batiza R (1989) Petrology and geochemistry of eastern Pacific spreading centers. In: Winterer
EL, Hussong DM, Decker RW (eds) The eastern pacific ocean and Hawaii: the geology of
North America. Geological Society America, Boulder, pp 145–160
Barclay AH, Toomey DR, Solomon SC (1998) Seismic structure and crustal magmatism at the
Mid-Atlantic Ridge, 35°N. J Geophys Res 103:17827–17844
Barberi F, Varet J (1970b) The Erta Ale volcanic range. Bull Volcanol Fascicule 4:848–917
250
7 Oceanic Spreading Ridges and Sea Floor Creation
linear volcanic ridges (Fig. 7.33).
2. An alternative hypothesis implies that hotspot-ridge interaction is mainly the
result of magma flow differentiation during the hot plume-derived melting
process (Niu et al. 1999; Hekinian 2004). In this case, the plume that gives rise
to hotspot volcanism is the main source for driving volcanic activity on the
ridge axis. Niu et al. (1999) suggested that much of the material needed to
create ocean crust and oceanic lithosphere must be supplied by lateral sublithospheric flow through the Low Velocity Zone (LVZ) at 670 km depth.
When this mantle material reaches the base of the lithosphere (70–100 km
depth), it flows laterally following the plate motion and the path of least
resistance, such as faults and fissures. When the plates diverge during spreading
at the ridge axis, it will drain the magma through the fissured and fractured
lithosphere. The ridge-ward flowing and melting plume material is progressively depleted in its enriched components as it approaches the ridge.
According to this hypothesis, the commonly interpreted geochemical ‘‘mixing’’
between compositionally distinct enriched-plume material and a depleted ‘‘MORB
source’’ in the context of a plume-ridge interaction is misleading. Hence, the
apparent ‘‘mixing relationship’’ observed in geochemistry could in fact be the
consequence of a partial melting of two different mantle sources.
References
Auzende J-M, Sinton J, Ballu V, Batiza R, Bideau D, Fouquet, Y, Cormier M-H, Geistdoerfer P,
Lagabrielle Y, and Piera Spadea P (1994) NAUDUR explorers discover recent volcanic
activity along the East Pacific Rise. Eos Trans Am Geophys Union 75(51):601, 604–605
Avedik F, Geli L (1987) Single-channel seismic reflection data from the East Pacific Rise axis
between latitude 11°50
0 and 12°54
0 N. Geology 15:857–860
Bäcker H, Lange H, Marchig V (1985) Hydrothermal activity and sulfide formation in axial
valley of the East Pacific Rise crest between 18°S and 22°S. Earth, Planet Sci Lett 72:9–22
Ballard RD (1983) Exploring our living Planet. National Geographical Society Washington D.C .,
p 366
Ballard RD, McConnell M (1995) Explorations: a life of underwater adventure. Hyperion, New
York, p 407
Barberi F, Varet J (1970a) The Erta Ale volcanic range (Danakil depression northern Afar,
Ethiopia). Bull Volcanol tome XXXIV, Fascicule 4:848–891
Batiza R (1981) Quantitative data on the abundance and distribution of seamounts in the Pacific
Ocean, McDonnell Center for Space Sciences Publ. MCP 498, p 23
Batiza R (1989) Petrology and geochemistry of eastern Pacific spreading centers. In: Winterer
EL, Hussong DM, Decker RW (eds) The eastern pacific ocean and Hawaii: the geology of
North America. Geological Society America, Boulder, pp 145–160
Barclay AH, Toomey DR, Solomon SC (1998) Seismic structure and crustal magmatism at the
Mid-Atlantic Ridge, 35°N. J Geophys Res 103:17827–17844
Barberi F, Varet J (1970b) The Erta Ale volcanic range. Bull Volcanol Fascicule 4:848–917
250
7 Oceanic Spreading Ridges and Sea Floor Creation