Melt Generation by Plumes: A Study of Hawaiian Volcanism

Watson, Sarah; McKenzie, Dan

doi:10.1093/petrology/32.3.501

Cited by 433 publications

(240 citation statements)

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“…In all cases it is assumed that melting begins and ends along one adiabatic path, and the primary magmas are formed by the integration of all fractional melts along the vertical streamline. Increasing mantle potential temperature initiates melting at higher pressures, and this produces primary magmas with higher MgO contents in all melting models [Klein and Langmuir, 1987;Niu and Batiza, 1991;Langmuir et al, 1992;Kinzler, 1997;McKenzie and Bickle, 1988;McKenzie and O'Nions, 1991;Watson and McKenzie, 1991;Herzberg and O'Hara, 2002;Asimow et al, 2001;Ghiorso and Sack, 1995]. All models provide the same T P for primary magmas with 10-13% MgO, but the variation can be ±50°C for primary magmas with 18-20% MgO relative to the model of Herzberg and O'Hara [2002].…”

Section: Analysis Of Temperature Uncertaintiesmentioning

confidence: 94%

Temperatures in ambient mantle and plumes: Constraints from basalts, picrites, and komatiites

Herzberg

Asimow

Arndt

et al. 2007

Geochem Geophys Geosyst

640

449

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International audienceSeveral methods have been developed to assess the thermal state of the mantle below oceanic ridges, islands, and plateaus, on the basis of the petrology and geochemistry of erupted lavas. One leads to the conclusion that mantle potential temperature (i.e., TP) of ambient mantle below oceanic ridges is 1430°C, the same as Hawaii. Another has ridges with a large range in ambient mantle potential temperature (i.e., TP = 1300–1570°C), comparable in some cases to hot spots (Klein and Langmuir, 1987; Langmuir et al., 1992). A third has uniformly low temperatures for ambient mantle below ridges, ∼1300°C, with localized 250°C anomalies associated with mantle plumes. All methods involve assumptions and uncertainties that we critically evaluate. A new evaluation is made of parental magma compositions that would crystallize olivines with the maximum forsterite contents observed in lava flows. These are generally in good agreement with primary magma compositions calculated using the mass balance method of Herzberg and O'Hara (2002), and differences reflect the well-known effects of fractional crystallization. Results of primary magma compositions we obtain for mid-ocean ridge basalts and various oceanic islands and plateaus generally favor the third type of model but with ambient mantle potential temperatures in the range 1280–1400°C and thermal anomalies that can be 200–300°C above this background. Our results are consistent with the plume model

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Section: Analysis Of Temperature Uncertaintiesmentioning

confidence: 94%

Temperatures in ambient mantle and plumes: Constraints from basalts, picrites, and komatiites

Herzberg

Asimow

Arndt

et al. 2007

Geochem Geophys Geosyst

640

449

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“…Volumetrically, the Banks Peninsula is the largest Miocene volcanic center on South Island, although production rates were low compared to typical hot spot driven volcanic activity [Watson and McKenzie, 1991].…”

Section: Davey Et Al 1998mentioning

confidence: 99%

Crustal structure and thermal anomalies of the Dunedin Region, South Island, New Zealand

Godfrey¹,

Davey²,

Stern³

et al. 2001

J. Geophys. Res.

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Abstract. Seven geophysical data sets are used to investigate a transect along the southeast coast of South Island, New Zealand. The specific focus of this study is the Dunedin volcanic center, which last produced volcanics at the surface 13-10 Myr ago. Wide-angle reflection/refraction seismic data along a two-dimensional profile reveal a lowvelocity lower crust and mantle beneath the Dunedin volcanic center. The low-velocity lower crust coincides with a highly reflective region on a nearby multichannel seismic line and may represent a hot, fluid-rich region of the crust. In addition, high mantle helium ratios measured in the Dunedin region suggest a current or recent mantle-melting event. High heat flow recorded in the Dunedin region is consistent with a hot body emplaced in the midcrust --•10 Myr ago (Miocene) whose heat is just reaching the surface today. Uplift of an Oligocene limestone horizon in the Canterbury basin can be explained by a buoyant load beneath the Dunedin volcanic center and low flexural rigidity of the lithosphere beneath the volcanic center during the Miocene. We interpret the data as revealing two separate thermal events beneath the Dunedin volcanic center, one during the Miocene, when volcanism was last occurring at the surface, and the other occurring currently. Active volcanism associated with the current mantle-melting event has yet to reach the surface. Geophysical Data and ModelsData used to develop and constrain models presented here are WAR/R seismic data, MCS data from industry and the SIGHT program, petrophysical measurements, and helium isotope and heat flow data. -1000 '• -, , , , , -, , , , , Figures 3a and 3b). On gather OBH 27, however, the Pn phase, which also passes through relatively fast lower crust (6.5-6.7 km s-•), can be flattened using an apparent velocity of---8.1 km s -• (Figure 3c Figures 5a and 5c) [Holt and Stem, 1994]. As SIGHT lines 4E and 25E approach Dunedin, this reflector is uplifted, and on SIGHT line 25E it is truncated at the surface (Figure 5c). It was presumably deposited horizontally, which makes it a useful marker horizon whose profile can be used to calibrate uplift. The age of uplift can be estimated from the age of the shallowest uplifted horizon on which there are onlapping sediments as seen on SIGHT line 4E (Figure 5a). Industry Well DataTwo industry wells either on, or close to, three of the SIGHT MCS lines (Figure lc) are used to date the horizon that we expect to be the Oligocene limestone and the shallowest uplifted horizon. We mapped both horizons from SIGHT line 4E to SIGHT lines 2E and 25E (Figure 5). On SIGHT lines 25E and 2E the deeper prominent reflector ties with the Oligocene limestone horizon in the well logs of the Galleon-1 well (Figures lc and 5c (Figures 5b and 5c).

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“…Eventually, it would become unstable [Christensen, 1984;Olson et al, 1987;Thompson and Tackley, 1998]. The instability of this layer would produce plumes with $1000 K temperature contrast, while the temperature contrast in the plumes is unlikely to be more than 300K [Watson and McKenzie, 1991]. A chemical boundary layer seems to be necessary to prevent plumes with large temperature contrasts [Farnetani, 1997].…”

Section: Instability Of the D 00 Layermentioning

confidence: 99%

Small‐scale convection in the D″ layer

Solomatov

Moresi

2002

J. Geophys. Res.

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[1] Small-scale convection has been suggested as a possible explanation for seismic heterogeneities in the D 00 layer of the Earth's mantle. Recently developed scaling laws for convection with realistic viscosities allow quantitative assessment of this hypothesis. Large temperature and viscosity contrasts across the thermal boundary layer at the core-mantle boundary suggest that small-scale convection starts at the bottom of the thermal boundary layer and propagates upward before the thermal boundary layer as a whole becomes unstable. The convection boundary is likely to become a chemical boundary as a result of mixing within the convective layer. This implies that the D 00 discontinuity can represent both convective and chemical boundary and that the presence or absence of small-scale convection can be responsible for the observed intermittent nature of the D 00 discontinuity. Most lateral heterogeneities in the D 00 layer are concentrated near the convection boundary, consistent with seismic data. The length scale of lateral temperature variations, the topography of the core-mantle boundary, and the viscosity of the D 00 layer are in agreement with observational constraints. The thickness of the secondary thermal boundary layer formed at the bottom of the convective layer is similar to the thickness of the ultralow-velocity zone. The magnitude of lateral variations in temperature can only marginally be responsible for lateral variations in seismic velocities. Variations in the topography of the convection boundary and chemical heterogeneities are likely to be more important factors. A large seismic velocity drop in the ultralow-velocity zone cannot be explained by thermal effects alone and must be caused by other factors such as partial melting.

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Melt Generation by Plumes: A Study of Hawaiian Volcanism

Cited by 433 publications

References 50 publications

Temperatures in ambient mantle and plumes: Constraints from basalts, picrites, and komatiites

Temperatures in ambient mantle and plumes: Constraints from basalts, picrites, and komatiites

Crustal structure and thermal anomalies of the Dunedin Region, South Island, New Zealand

Small‐scale convection in the D″ layer

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