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  • 1
    Call number: M 20.93496
    Description / Table of Contents: According to the classical plume hypothesis, mantle plumes are localized upwellings of hot, buoyant material in the Earth’s mantle. They have a typical mushroom shape, consisting of a large plume head, which is associated with the formation of voluminous flood basalts (a Large Igneous Province) and a narrow plume tail, which generates a linear, age-progressive chain of volcanic edifices (a hotspot track) as the tectonic plate migrates over the relatively stationary plume. Both plume heads and tails reshape large areas of the Earth’s surface over many tens of millions of years. However, not every plume has left an exemplary record that supports the classical hypothesis. The main objective of this thesis is therefore to study how specific hotspots have created the crustal thickness pattern attributed to their volcanic activities. Using regional geodynamic models, the main chapters of this thesis address the challenge of deciphering the three individual (and increasingly complex) Réunion, Iceland, and Kerguelen hotspot histories,…
    Type of Medium: Dissertations
    Pages: 104 Seiten , Illustrationen, Diagramme, Karten
    Language: English
    Location: Upper compact magazine
    Branch Library: GFZ Library
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  • 2
    Publication Date: 2007-10-08
    Description: Formation of the Ontong Java Plateau (OJP), a large igneous province in the western Pacific, has been attributed to a rising plume head in the initial stage of the Louisville hot spot, approximately 120-125 Ma ago. However, the Neal et al. plate reconstruction suggests that the plateau formed approximately 9{degrees} north of the current location of this hot spot at 51{degrees}S. The magnetization of the plateau's basement records a palaeolatitude of approximately 25{degrees}S which further increases the discrepancy with the plume-head model. Modelling the motion of the Louisville hot spot for the last 120 Ma yields a possible southward motion of up to about 6{degrees}. True polar wander (TPW) models also shift the predicted palaeolatitudes of the plateau farther north. Taking into account both hot-spot motion and TPW, formation of the OJP by the Louisville not spot remains a possibility.
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  • 3
    Publication Date: 2019-07-16
    Description: Estimates of the relative motion between the Hawaiian and Louisville hot spots have consequences for understanding the role and character of deep Pacific-mantle return flow. The relative motion between these primary hot spots can be inferred by comparing the age records for their seamount trails. We report 40Ar/39Ar ages for 18 lavas from 10 seamounts along the Hawaiian-Emperor Seamount Chain (HESC), showing that volcanism started in the sharp portion of the Hawaiian-Emperor Bend (HEB) at ≥47.5 Ma and continued for ≥5 Myr. The slope of the along-track distance from the currently active Hawaiian hot spot plotted versus age is constant (57 ± 2 km/Myr) between ∼57 and 25 Ma in the central ∼1900 km of the seamount chain, including the HEB. This model predicts an age for the oldest Emperor Seamounts that matches published ages, implying that a linear age-distance relationship might extend back to at least 82 Ma. In contrast, Hawaiian age progression was much faster since at least ∼15 Ma and possibly as early as ∼27 Ma. Linear age-distance relations for the Hawaii-Emperor and Louisville seamount chains predict ∼300 km overall hot spot relative motion between 80 and 47.5 Ma, in broad agreement with numerical models of plumes in a convecting mantle, and paleomagnetic data. We show that a change in hot spot relative motion may also have occurred between ∼55 Ma and ∼50 Ma. We interpret this change in hot spot motion as evidence that the HEB reflects a combination of hot spot and plate motion changes driven by the same plate/mantle reorganization.
    Repository Name: EPIC Alfred Wegener Institut
    Type: Article , NonPeerReviewed
    Format: application/pdf
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  • 4
    Publication Date: 2017-03-20
    Description: Northwestern Namibia, at the landfall of the Walvis Ridge, was affected by the Tristan da Cunha mantle plume during continental rupture between Africa and South America, as evidenced by the presence of the Etendeka continental flood basalts. Here we use data from a passive-source seismological network to investigate the upper mantle structure and to elucidate the Cretaceous mantle plume-lithosphere interaction. Receiver functions reveal an interface associated with a negative velocity contrast within the lithosphere at an average depth of 80 km. We interpret this interface as the relic of the lithosphereasthenosphere boundary (LAB) formed during the Mesozoic by interaction of the Tristan da Cunha plume head with the pre-existing lithosphere. The velocity contrast might be explained by stagnated and ‘‘frozen’’ melts beneath an intensively depleted and dehydrated peridotitic mantle. The present-day LAB is poorly visible with converted waves, indicating a gradual impedance contrast. Beneath much of the study area, converted phases of the 410 and 660 km mantle transition zone discontinuities arrive 1.5 s earlier than in the landward plume-unaffected continental interior, suggesting high velocities in the upper mantle caused by a thick lithosphere. This indicates that after lithospheric thinning during continental breakup, the lithosphere has increased in thickness during the last 132 Myr. Thermal cooling of the continental lithosphere alone cannot produce the lithospheric thickness required here. We propose that the remnant plume material, which has a higher seismic velocity than the ambient mantle due to melt depletion and dehydration, significantly contributed to the thickening of the mantle lithosphere.
    Repository Name: EPIC Alfred Wegener Institut
    Type: Article , NonPeerReviewed
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  • 5
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    GFZ Data Services
    Publication Date: 2019-10-03
    Description: TechnicalInfo
    Description: The data are the modelling results for Yellowstone hotspot motion and plume conduits on which the figures of the paper "Yellowstone plume conduit tilt caused by large-scale mantle flow" by Steinberger, Nelson, Grand and Wang are based. Detailed description on how they are obtained is given in that paper.The naming of the files is as follows: First letter: c for plume conduit, s for surface motion. Then figure number (6, 7, or 8; s1 and s2 for Supporting Figure 1 and 2), then a, b, c or d for which column of the figure, or 2a etc for the specific panel. Each file has in the first column time, in the second longitude, in the third latitude, in the fourth depth (given as normalized radius, i.e. 1 at the surface, 0.5448 at the core-mantle boundary). For the plume conduit the time (first column) is always zero = present-day. For the surface motion the depth is always close to 0.9843 (base of the lithosphere). The file rotvec.na.nn gives the North America plate motion (stage rotations) used to convert hotspot motions to hotspot tracks on the North American plate. Stage rotation rates are given in omega_x, omega_y, omega_z (units of degrees per million years) followed by the time interval in million.Stage rotation rates are given in cartesian coordinates omega_x, omega_y, omega_z (units of degrees per million years) followed by the time interval in million years.
    Keywords: mantle plume ; hotspot ; mantle flow ; mantle processes ; EARTH SCIENCE 〉 SOLID EARTH 〉 TECTONICS 〉 CORE PROCESSES ; EARTH SCIENCE 〉 SOLID EARTH
    Type: Dataset
    Format: 1 Files
    Format: application/octet-stream
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  • 6
    ISSN: 1476-4687
    Source: Nature Archives 1869 - 2009
    Topics: Biology , Chemistry and Pharmacology , Medicine , Natural Sciences in General , Physics
    Notes: [Auszug] The bend in the Hawaiian-Emperor seamount chain is a prominent feature usually attributed to a change in Pacific plate motion ∼47 Myr ago. However, global plate motion reconstructions fail to predict the bend. Here we show how the geometry of the Hawaiian-Emperor chain and other hotspot ...
    Type of Medium: Electronic Resource
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  • 7
    Electronic Resource
    Electronic Resource
    [s.l.] : Nature Publishing Group
    Nature 387 (1997), S. 169-173 
    ISSN: 1476-4687
    Source: Nature Archives 1869 - 2009
    Topics: Biology , Chemistry and Pharmacology , Medicine , Natural Sciences in General , Physics
    Notes: [Auszug] The rotational bulge tends to stabilize the location of the pole, but the bulge can readjust by plastic flow to a change in the position of the rotation axis. If the timescale for the adjustment of the bulge is short enough, the location of the rotation pole is determined by the location of the ...
    Type of Medium: Electronic Resource
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  • 8
    Publication Date: 2020-02-06
    Description: The orientation and tectonic regime of the observed crustal/lithospheric stress field contribute to our knowledge of different deformation processes occurring within the Earth's crust and lithosphere. In this study, we analyze the influence of the thermal and density structure of the upper mantle on the lithospheric stress field and topography. We use a 3-D lithosphere–asthenosphere numerical model with power-law rheology, coupled to a spectral mantle flow code at 300 km depth. Our results are validated against the World Stress Map 2016 (WSM2016) and the observation-based residual topography. We derive the upper mantle thermal structure from either a heat flow model combined with a seafloor age model (TM1) or a global S-wave velocity model (TM2). We show that lateral density heterogeneities in the upper 300 km have a limited influence on the modeled horizontal stress field as opposed to the resulting dynamic topography that appears more sensitive to such heterogeneities. The modeled stress field directions, using only the mantle heterogeneities below 300 km, are not perturbed much when the effects of lithosphere and crust above 300 km are added. In contrast, modeled stress magnitudes and dynamic topography are to a greater extent controlled by the upper mantle density structure. After correction for the chemical depletion of continents, the TM2 model leads to a much better fit with the observed residual topography giving a good correlation of 0.51 in continents, but this correction leads to no significant improvement of the fit between the WSM2016 and the resulting lithosphere stresses. In continental regions with abundant heat flow data, TM1 results in relatively small angular misfits. For example, in western Europe the misfit between the modeled and observation-based stress is 18.3°. Our findings emphasize that the relative contributions coming from shallow and deep mantle dynamic forces are quite different for the lithospheric stress field and dynamic topography.
    Type: Article , PeerReviewed
    Format: text
    Format: text
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  • 9
    Publication Date: 2019-02-01
    Description: Ice-penetrating radar1,2,3 and ice core drilling4 have shown that large parts of the north-central Greenland ice sheet are melting from below. It has been argued that basal ice melt is due to the anomalously high geothermal flux1,4 that has also influenced the development of the longest ice stream in Greenland1. Here we estimate the geothermal flux beneath the Greenland ice sheet and identify a 1,200-km-long and 400-km-wide geothermal anomaly beneath the thick ice cover. We suggest that this anomaly explains the observed melting of the ice sheet’s base, which drives the vigorous subglacial hydrology3 and controls the position of the head of the enigmatic 750-km-long northeastern Greenland ice stream5. Our combined analysis of independent seismic, gravity and tectonic data6,7,8,9 implies that the geothermal anomaly, which crosses Greenland from west to east, was formed by Greenland’s passage over the Iceland mantle plume between roughly 80 and 35 million years ago. We conclude that the complexity of the present-day subglacial hydrology and dynamic features of the north-central Greenland ice sheet originated in tectonic events that pre-date the onset of glaciation in Greenland by many tens of millions of years.
    Type: Article , PeerReviewed
    Format: text
    Format: text
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  • 10
    Publication Date: 2002-11-01
    Electronic ISSN: 1525-2027
    Topics: Chemistry and Pharmacology , Geosciences , Physics
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