DOMAL TOP TB 65 PDF
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Experimentally based water budgets for dehydrating slabs and consequences for arc magma generation. Grain-size reduction by subgrain rotation marks larger amounts of strain and probably higher stress during flow by dislocation creep than the type 1 texture. The vertical attitude is prominent in less preferred models kofm and kofn Models 6 and 7 in Table 5 ; Fig.
What olivine, the neglected mineral, tells us about kimberlite petrogenesis. Oxford University Press is a department of the University of Oxford. Contemporaneous derivatives of silicate melt—harzburgite reaction. Intrusion of ultramafic magmatic bodies into the continental crust: Although the Riphean sediments define a dome-like structure, the inward, shallow dipping foliation of the dunites indicates a synformal structure.
Receive exclusive offers and updates from Oxford Academic. Variations in final shapes and internal geometry of intrusions with varying numerical model parameters Table 5. Effects of mineralogical reactions on trace element redistributions in mantle rocks during percolation processes: Predominant minerals are shown in bold.
The tectonics of the Platinum-Bearing Belt of the Urals: Ultramafic and mafic rocks follow the extruded and eroded lower crustal spine and intrude the upper crust up to near-surface conditions within c. Melt migration under oceanic ridges: Mineral lineation trajectories are concentric Fig.
This is confirmed by varying the initial cohesion of the upper crust compare models kofh and kofz; Models 1 and 11 in Table 5 ; Fig. Consequently, surface deformation is also localized, as the faults do not propagate laterally from the emplacement area. View large Download slide.
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The outward textural change from coarse- to fine-grained equigranular dunite and the outward-increasing abundance of subgrains and recrystallized olivine grains suggest dynamic recrystallization while fluid circulation was channelized within the core metasomatic zone, with a decreasing melt fraction from core to rop, and also suggest that solid-state deformation induced grain-size reduction towards the cooling border of the Kondyor massif.
The strong enrichments in Rb, Cs and Ba in several samples are clearly related to the presence of phlogopite. However, the decreasing values of Mg-number and Ni content towards the margin Fig. Textures left and olivine fabrics stereograms in dunites representative of the three domains Fig.
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Subduction-related ZUCs form linear belts and are surrounded by large gabbroic bodies e. The petro-structural study indicates that the Kondyor dunites were deformed by solid-state flow under deep-lithospheric to asthenospheric conditions.
Two important features characterize the pressure distribution: Other implications may concern melt extraction from the mantle, with new constraints on the focusing mechanism of vertical melt flow. For example, a huge block of lower crustal rocks caps the ultrabasic rocks of kofn, which is inconsistent with the geological information. Deep-seated partial melts migrating upward tend to dissolve the pyroxene component of percolated peridotites and crystallize olivine, leading to the formation of olivine-rich rocks Kelemen, The ultramafic rocks are subdivided into three subconcentric lithologies, from core to rim: Such conditions are expected for anorogenic A-type magmatism, which is particularly common in Proterozoic terranes e.
The dunite texture varies from coarse-grained 2—3 cmsometimes tabular, in the core to fine-grained against the rim contact. Nature of the upper mantle and metasomatic processes on either side of the Sillon Houiller French Massif Central. The ductile flow law of the crust Table 5 plays a subordinate role.
The intrusion model developed for Kondyor is potentially applicable to other types of magmatic rock that originated at sub-lithospheric depths. Model 5, kofl, Table 5Fig. The classical relationships close to foliation and  close to lineation imply that the slip system was  Published by Oxford University Press.
Other constraints were the preservation of basement slivers around the peridotite body, a narrow thermal aureole around it and slightly asymmetrical, concentric zoning with a fluid-rich medial zone. Such reactions were probably involved in the formation of the Kondyor rim pyroxenites.
Whole-rock data are reported in Table 3. Like many other intra-plate ZUCs, Kondyor exhibits several features that are difficult to explain in terms of an igneous origin.
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The main secondary minerals include: As such, the peripheral gabbros resemble the gabbro dykes. The inclusions are of coarser-grained, darker gabbro, which suggests comagmatism. Lallemant, and subsequent lithospheric break-up above mantle plumes. This is markedly different from the case where production of fluid-rich melts in the SMSR builds up high fluid pressure, which precludes substitution by the surrounding mantle and enhancement of escape of the molten fraction into the forming magmatic channel e.
The initial thermal structure of the lithosphere is as usually assumed, with a 35 km thick crust Fig. Olivine xenocrysts in kimberlites, for example, have been attributed to olivine crystallization and melt—rock interaction Arndt et al. The bulk synformal structure of the dunite foliation seems something of a paradox in the context of the Kondyor dome defined by the surrounding Riphean sediments. First, the transition from dunite to differentiated clinopyroxenite cumulates is gradual, through clinopyroxene-bearing dunite and wehrlite with replacive textures Fig.
Origin of the Tulameen ultramafic—gabbro complex, southern British Columbia. It furthers the University’s objective of excellence in research, scholarship, and education by publishing worldwide. The lower and especially the upper continental crust should be sufficiently dry and cold to have a high initial plastic strength and to focus strongly intrusion between subvertical faults. Origin of the island arc Moho transition zone via melt—rock reaction and its implications for intracrustal fractionation of island arcs: