Seismicity in the Vicinity of the Tristan Da Cunha Hot Spot: Particular Plate Tectonics and Mantle Plume Presence

John Tuzo Wilson coined the term “plate” in plate tectonics. He is famous for inventing transform boundaries, hot spot tracks, and the Wilson cycle of ocean birth, growth, and decline. Less well remembered is his work in the 1950s on tectonic and radiometric age provinces of the Canadian Shield, as part of which he fathered U/Pb geochronology in Canada. This work gave strong support to the notion of continental growth through accretion of successively younger terranes onto an ancient cratonic core. The present paper reviews how paleomagnetism can trace the motions of continents to test Wilson’s ideas. Continental accretion often involves deep burial of one of the colliding elements through subduction or crustal underplating; such was the case with the Grenville orogen and its subprovinces in their Proterozoic accretion onto the Laurentian craton. The resulting heating and metamorphism erases most pre-collisional magnetic information but adds something new: the possibility of following the post-metamorphic uplift and cooling history, in time and space. The time element is provided by a new form of isotopic geochronology, thermochronometry, which provides dates for specific minerals together with the temperatures at which they became closed to isotopic migration. U/Pb dating of sphene is one method used; another is the 40Ar/39Ar variant of K/Ar dating applied to hornblende, micas, and feldspars, which have a wide range of Ar closure temperatures. The two specific Grenville studies described deal with parallel uplift histories determined by 40Ar/39Ar dating and by magnetics for the accreted terranes of the Central Metasedimentary Belt in Ontario and with the paleomagnetic detection of the post-1240 Ma closing of a small ocean between the Elsevir terrane and Laurentia during the Grenvillian orogeny.

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Corona structures driven by plume-lithosphere interactions and evidence for ongoing plume activity on Venus

10.31223/x5jk88 ◽

2021 ◽

Author(s):

Anna Gülcher ◽

Laurent Montési ◽

Taras Gerya ◽

Jessica Munch

Keyword(s):

Numerical Simulations ◽

Mantle Plume ◽

Mantle Convection ◽

Plate Tectonics ◽

Morphological Analysis ◽

Surface Deformation ◽

Tectonic Structures ◽

Thickness Variations ◽

Tectonic Features ◽

Topographic Inversion

In the absence of global plate tectonics, mantle convection and plume-lithosphere interaction are the main drivers of surface deformation on Venus. Among documented tectonic structures, circular volcano-tectonic features known as coronae may be the clearest surface manifestations of mantle plumes and hold clues to the global Venusian tectonic regime. Yet, the exact processes underlying coronae formation and the reasons for their diverse morphologies remain controversial. Here, we use 3D thermomechanical numerical simulations of impingement of a thermal mantle plume upon the Venusian lithosphere to assess the origin and diversity of large Venusian coronae. The ability of the mantle plume to penetrate into the Venusian lithosphere results in four main outcomes: lithospheric dripping, short-lived subduction, embedded plume and plume underplating. During the first three scenarios, plume penetration and spreading induce crustal thickness variations that eventually lead to a final topographic isostasy-driven topographic inversion from circular trenches surrounding elevated interiors to raised rims surrounding inner depressions, as observed on many Venusian coronae. Different corona structures may represent not only different styles of plume-lithosphere interactions, but also different stages in evolution. A morphological analysis of large existing coronae leads to the conclusion that least 37 large coronae (including the largest Artemis corona) are active, providing evidence for widespread ongoing plume activity on Venus.

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Thickness of the oceanic crust, the lithosphere, and the mantle transition zone in the vicinity of the Tristan da Cunha hot spot estimated from ocean-bottom and ocean-island seismometer receiver functions

Tectonophysics ◽

10.1016/j.tecto.2016.12.013 ◽

2017 ◽

Vol 716 ◽

pp. 33-51 ◽

Cited By ~ 12

Author(s):

Wolfram H. Geissler ◽

Wilfried Jokat ◽

Marion Jegen ◽

Kiyoshi Baba

Keyword(s):

Transition Zone ◽

Oceanic Crust ◽

Hot Spot ◽

Receiver Functions ◽

Ocean Bottom ◽

Mantle Transition Zone ◽

Ocean Island ◽

Tristan Da Cunha

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The evolution of the earth's crust: Modern plate tectonics to ancient hot spot tectonics?

Chemical Geology ◽

10.1016/0009-2541(78)90068-2 ◽

1978 ◽

Vol 23 (1-4) ◽

pp. 89-114 ◽

Cited By ~ 229

Author(s):

W.S. Fyfe

Keyword(s):

Plate Tectonics ◽

Hot Spot ◽

Earth’S Crust ◽

Earth's Crust

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Seafloor evidence for pre-shield volcanism above the Tristan da Cunha mantle plume

Nature Communications ◽

10.1038/s41467-020-18361-4 ◽

2020 ◽

Vol 11 (1) ◽

Author(s):

Wolfram H. Geissler ◽

Paul Wintersteller ◽

Marcia Maia ◽

Anne Strack ◽

Janina Kammann ◽

...

Keyword(s):

Hot Spot ◽

Habitat Mapping ◽

Gis Analysis ◽

Submarine Eruption ◽

Core Complex ◽

Mapping Algorithms ◽

Walvis Ridge ◽

Tristan Da Cunha ◽

Magma Supply ◽

Mid Atlantic Ridge

Abstract Tristan da Cunha is assumed to be the youngest subaerial expression of the Walvis Ridge hot spot. Based on new hydroacoustic data, we propose that the most recent hot spot volcanic activity occurs west of the island. We surveyed relatively young intraplate volcanic fields and scattered, probably monogenetic, submarine volcanoes with multibeam echosounders and sub-bottom profilers. Structural and zonal GIS analysis of bathymetric and backscatter results, based on habitat mapping algorithms to discriminate seafloor features, revealed numerous previously-unknown volcanic structures. South of Tristan da Cunha, we discovered two large seamounts. One of them, Isolde Seamount, is most likely the source of a 2004 submarine eruption known from a pumice stranding event and seismological analysis. An oceanic core complex, identified at the intersection of the Tristan da Cunha Transform and Fracture Zone System with the Mid-Atlantic Ridge, might indicate reduced magma supply and, therefore, weak plume-ridge interaction at present times.

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What triggered the early-stage eruption of the Emeishan large igneous province?

Geological Society of America Bulletin ◽

10.1130/b35030.1 ◽

2019 ◽

Vol 131 (11-12) ◽

pp. 1837-1856 ◽

Cited By ~ 3

Author(s):

Bei Zhu ◽

Zhaojie Guo ◽

Shaonan Zhang ◽

Ingrid Ukstins ◽

Wei Du ◽

...

Keyword(s):

Mantle Plume ◽

Plate Tectonics ◽

Early Stage ◽

Volcanic Rocks ◽

Large Igneous Province ◽

Background Information ◽

Gradual Transition ◽

Emeishan Large Igneous Province ◽

Igneous Province ◽

Back Arc

Abstract The formation of the Emeishan large igneous province is widely regarded as being related to a mantle plume, but plate tectonics may also have played an important role. We analyzed the regional facies architecture of the early-stage subaqueous volcanic rocks of the central Emeishan large igneous province. The results suggest that these rocks were emplaced in a N-S–striking subaqueous rift, which existed immediately before the onset of volcanism and was persistently maintained during the early eruption stage. By linking this conclusion with the background information indicating that (1) the basaltic geochemistry in this section is indicative of a subcontinental lithospheric mantle source rather than a mantle plume source, and (2) the western Yangtze plate, where the Emeishan large igneous province was developed, was located in the back-arc region of the Permian Paleo-Tethys subduction system, we propose a new view that the early-stage eruptions of the Emeishan large igneous province were triggered by back-arc extension. The dominant functioning of the mantle plume occurred shortly after this process and inherited it, as evidenced by the following: (1) The subaqueous volcanic architecture showing back-arc geochemical affinity is laterally restricted in the presumed rift, but the overlying subaerial lavas showing plume-related geochemical features overwhelmingly flooded the whole province; (2) vertically, the source of the basaltic component in these intrarift sequences underwent a gradual transition from lithospheric origin to mantle plume origin along the stratigraphic order, as evidenced by an intercalated basaltic succession showing mixed geochemical features from the two contextual origins.

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