Rough versus smooth topography along oceanic hotspot tracks: Observations and scaling analysis

Abstract

Some hotspot tracks are topographically smooth and broad (Nazca, Carnegie/Cocos/Galápagos, Walvis, Iceland), while others are rough and discontinuous (Easter/Sala y Gomez, Tristan‐Gough, Louisville, St. Helena, Hawaiian‐Emperor). Smooth topography occurs when the lithospheric age at emplacement is young, favoring intrusive magmatism, whereas rough topography is due to isolated volcanic edifices constructed on older/thicker lithosphere. The main controls on the balance of intrusive versus extrusive magmatism are expected to be the hotspot swell volume flux Qs, plate hotspot relative speed v, and lithospheric elastic thickness Te, which can be combined as a dimensionless parameter R = (Qs/v)1/2/Te, which represents the ratio of plume heat to the lithospheric heat capacity. Observational constraints show that, except for the Ninetyeast Ridge, R is a good predictor of topographic character: for R < 1.5 hotspot tracks are topographically rough and dominated by volcanic edifices, whereas for R > 3 they are smooth and dominated by intrusion.

Structure of the Collision Zone Between the Nazca Ridge and the Peruvian Convergent Margin: Geodynamic and Seismotectonic Implications

“…This anomalous density contrast causes strong buoyancy forces and subsequently the formation of the broad swell (shallow seafloor) topography (McNutt & Bonneville, 2000; see detailed discussion of the swell topography in the next subsection). For the case of the NR, the swell surface is up to 1.5 km shallower than the surrounding seafloor (Figures 1 and 2) and is characterized by a smooth morphology compared to other hot spot tracks formed by hot spot plumes located far from active spreading centers such as the Juan Fernandez Ridge and the Hawaiian volcanic chain (e.g., Orellana-Rovirosa & Richards, 2017). According to these authors, the smooth swell topography occurs when the hot spot plume is overlying by an oceanic lithosphere young, and therefore weak, thin, and hot, allowing voluminous melt penetration and crustal intrusion.…”

“…For example, seamounts formed near a spreading center on weak oceanic plate (on-ridge seamounts like the Cocos and Nazca ridges) are locally more compensated and more buoyant (Watts et al, 2010), and thus, an important coupling at the subduction interface is expected. In addition, these oceanic ridges are characterized by a smooth and broad morphology (Orellana-Rovirosa & Richards, 2017) and more basal subduction erosion beneath the upper plate rather than frontal subduction erosion at the front of the upper plate is hypothesized (Contreras-Reyes & Carrizo, 2011). In contrast, oceanic ridges formed far from oceanic spreading center (off-ridge seamounts like the Juan Fernandez and Louisville ridges) are more regionally compensated, and therefore less buoyant (Watts et al, 2010), and host a rough and narrow morphology (Orellana-Rovirosa & Richards, 2017).…”

“…In addition, these oceanic ridges are characterized by a smooth and broad morphology (Orellana-Rovirosa & Richards, 2017) and more basal subduction erosion beneath the upper plate rather than frontal subduction erosion at the front of the upper plate is hypothesized (Contreras-Reyes & Carrizo, 2011). In contrast, oceanic ridges formed far from oceanic spreading center (off-ridge seamounts like the Juan Fernandez and Louisville ridges) are more regionally compensated, and therefore less buoyant (Watts et al, 2010), and host a rough and narrow morphology (Orellana-Rovirosa & Richards, 2017). Thus, heterogeneous and/or weaker coupling at the subduction contact (Wang & Bilek, 2011;Watts et al, 2010) and more frontal subduction erosion are expected to occur (Dominguez et al, 1998;Ranero & von Huene, 2000).…”

Emergence/Subsidence Histories Along the Carnegie and Cocos Ridges and Their Bearing Upon Biological Speciation in the Galápagos

“…Geodynamic considerations show that hotspot tracks are characterized by time‐dependent topography, with elevated topography above and in the vicinity of the underlying plume conduit (Davies, ; Ribe & Christensen, ), responding to the fluid dynamics of ponding and buoyancy of highly viscous flows (Sleep, ). Aside from this, geophysical studies have demonstrated the regular time dependence of ocean basin depth with plate age (Johnson & Carlson, ), as well as the associated effects upon volcanism (Orellana‐Rovirosa & Richards, ). Below we review how mechanical and thermodynamic considerations regarding plate tectonics, mantle plume dynamics, crustal dynamics, and volcanism can account for paleo‐elevations with respect to the current topography/bathymetry of the region.…”

Geological structure and features of Mesozoic-Cenozoic stage of development of a Southern part of the East Indian Ridge, Indian Ocean

“…При объяснении морфологического облика того или иного «трас сера» основной упор делается на кинематические особенности и скорость дрейфа океанической плиты в сочетании с магматичес кой активностью «горячей точки». По особенностям взаимодей ствия этих процессов «трассеры» могут быть прерывистые (к ним, например, относят Гавайский хребет), или сплошные, типа хребта Наска [22]. Структурные особенности ВИХ, как «трассера горячей точки», рас сматриваются в работах последних лет [17, 24, 25, 26 и др.…”