Ice flow vectors on the debris-mantled Tasman Glacier, 1957-1986
This paper examines the debris-mantled zone of Tasman Glacier for evidence of debris mantle formation. Particularly, the velocity distribution and surface morphology are studied to understand the extent and rate of ice stagnation and the process
The initial cause of vertical motions in the mantle and the atmosphere
Atmosphere ; Geophysics ; Global tectonics ; Mantle ; Mathematical model ; Meteorology ; Model ; Orogeny ; Sea-floor spreading ; Vertical movement
This paper intends to touch on the initial cause of motions in the fluids in gravity field, eg. the mantle and the atmosphere, and it is hoped that it will be helpful in solving the concerned basc problems both in geology and in meteorology.
Phase transformations and the constitution of the deep mantle in The Earth: its origin, structure and evolution.
Recent experimental investigations on the phase transformations of mantle silicates at high pressure and high temperature conditions are reviewed. The mineralogy and structure of the Earth's mantle, especially at depths below 500 km, are proposed
Subduction, the geoid, and lower mantle convection
Geoid models show that net uncompensated masses in subducting lithosphere are less than thermal models predict, and do not require elevation of mantle phase changes in the slabs. The largest deviations from hydrostatic equilibrium ignore plate
boundaries and may be ascribed to lower mantle convection uncoupled to plate motions.
Fluid models of mantle convection in The Earth: its origin, structure and evolution.
It is shown that a variety of indirect evidence, especially postglacial uplift and gravity data, together with an increasing theoretical and laboratory understanding of model systems, suggests convection throughout the mantle, although the flow may
be in the form of coupled layers rather than overturning of the whole mantle. The relationship of this convection to plate tectonics is discussed, with emphasis on subduction as a form of thermal convection in which the mantle is cooled from above.
Enriched mantle: Nd and Sr isotopes in diopsides from kimberlite nodules
Nd and Sr isotope compositions of diopsides from micaceous garnet lherzolite nodules found in kimberlite pipes at Bultfontein and Kimberley, South Africa are reported. The diopside data extend the mantle array, as defined by uncontamined oceanic
and continental basalts, to radiogenic Sr/Sr values. These data are used to demonstrate the ancient enriched, grossly heterogeneous nature of the sub-continental mantle, which complements the predominantly depleted nature of the sub-oceanic mantle.
Thermal modelling suggests that the problems posed by the high liquid temperatures (1,650C) of peridotitic lavas in Archaean greenstone belts, and the implied high degree of mantle melting (70%), are significantly reduced by considering uprise
of a more refractory mantle diapir having an inherent density contrast with the surrounding mantle, and in a tectonic environment analogous to a marginal basin.
Lithological evidence for the evolution of weathered mantles in Uganda by tectonically controlled cycles of deep weathering and stripping
In this study, a tectonic model of landscape evolution recently developed for Uganda, was tested by detailed study of the weathered mantle. The study involved an analysis of weathered-mantle stratigraphy, texture, mineralogy and elemental
Subsurface hydrology of layered colluvium mantles in unchanneled valleys, South-Eastern Brazil
The effects of subsurface hydrology on the evolution of erosive processes inside layered colluvium mantles in unchannelled valleys are investigated. Tensiometer nests were installed in different morphological conditions with their specific depths
controlled by the subsurface structure of the colluvium mantle. Daily readings (during one year) and physical and mechanical analyses of the different colluvium layers were carried out.
The mechanical behaviour of rock under crustal and mantle conditions in The Earth: its origin, structure and evolution.
A brief survey is given of the types of mechanical behaviour that might be expected in the crust and mantle in the light of recent experimental studies. Emphasis is placed on the variety of possible behaviour and the difficulties that arise out
of this variety in making relevant extrapolations from the time scale of experiments to that of natural deformations. The particular case of olivine-rich rocks, of interest in mantle studies, is taken up in more detail, with a critical survey of available
Holocene fluctuations in sea level: constraints on mantle viscosity and melt-water sources in Proceedings. Volume 3. Symposia and seminars.
Sea-level data from various localities in the south Pacific are used in an attempt to constrain rheological models for the mantle and to evaluate melting models for ice sheets. A value of 10 poise is suggested as most likely for effective Newtonian
The primordial chondritic nature and large-scale heterogeneities in the mantle: evidence from high and low partition coefficient elements in oceanic basalts
On overlapping sections and drill cores of an autochthonous paleosoil and the saprolite underneath, the morphological, geochemical and mineralogical zonation of a complete profile of the weathering mantle has been reconstructed. The data indicate
a polygenesis of the weathering mantle during the Tertiary, due to descending groundwater tables caused by the beginning tectonic uplift of the Rhenish Massif and drier climatic periods during the Middle Tertiary. Periglacial processes during the Pleistocene led