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cone sheets

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Journal Article
Published: 01 September 1971
Geological Magazine (1971) 108 (5): 373–376.
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Figure 5.
Published: 12 January 2015
Figure 5. Model of sequential emplacement of cone sheets as proposed by Lurie (unpub. Ph.D. thesis, Rhodes Univ., 1973) along a W–E section through the centre of the complex. The emplacement order is as proposed by Lurie. Section 1 shows
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(a) Photograph looking along the strike of two cone sheets that are cut by a ridge of Glas Bheinn Porphyritic Dolerite. (b) Close-up photograph of the inferred chill zone. Plagioclase phenocrysts (white arrows) are absent from the chilled region. (c) Cross-polarized photomicrograph from the chilled Glas Bheinn Porphyritic Dolerite showing a fine groundmass of skeletal plagioclase (Pl gm), clinopyroxene (Cpx), magnetite (Mg) and an area of intense alteration to clay minerals (Cy). Note the absence of any phenocrysts. See (b) for sample position.
Published: 01 November 2012
Fig. 4. ( a ) Photograph looking along the strike of two cone sheets that are cut by a ridge of Glas Bheinn Porphyritic Dolerite. ( b ) Close-up photograph of the inferred chill zone. Plagioclase phenocrysts (white arrows) are absent from the chilled region. ( c ) Cross-polarized photomicrograph
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Magma fingers (in cross-section) within dolerite cone sheets of Ardnamurchan, Scotland. The magma was emplaced at a depth no greater then several hundred metres, leading to ductile deformation and non-brittle behaviour of host rock during intrusion.
Published: 01 March 2012
Fig. 8. Magma fingers (in cross-section) within dolerite cone sheets of Ardnamurchan, Scotland. The magma was emplaced at a depth no greater then several hundred metres, leading to ductile deformation and non-brittle behaviour of host rock during intrusion.
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Stereograms of measurement sites around Loch Coruisk, for cone sheets not plotted on the stereogram in Figure 3a. The sheets dip towards the same focus zone as the other sheets. (See Fig. 4 for location.)
Published: 01 May 2011
Fig. 5. Stereograms of measurement sites around Loch Coruisk, for cone sheets not plotted on the stereogram in Figure 3 a. The sheets dip towards the same focus zone as the other sheets. (See Fig. 4 for location.)
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Cone sheets, dykes and related stereograms around the Elgol peninsula not plotted on the stereogram in Figure 3a. (a) Low-angle sheets near the village of Elgol. (b) Photograph of NNW–SSE-striking dykes located on the east side of the peninsula. The low-angle sheets dip towards the same focus zone as the other sheets. (See Fig. 4 for location.)
Published: 01 May 2011
Fig. 6. Cone sheets, dykes and related stereograms around the Elgol peninsula not plotted on the stereogram in Figure 3 a. ( a ) Low-angle sheets near the village of Elgol. ( b ) Photograph of NNW–SSE-striking dykes located on the east side of the peninsula. The low-angle sheets dip towards
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(a) Number of cone sheets (frequency) plotted against dip angles, showing a Gaussian distribution with peaks around 40–50°. (b) Dip (inclination) and altitude were compared to determine if there are changes in sheet geometry at different depths of emplacement. These graphs show that there is no correlation.
Published: 01 May 2011
Fig. 7. ( a ) Number of cone sheets (frequency) plotted against dip angles, showing a Gaussian distribution with peaks around 40–50°. ( b ) Dip (inclination) and altitude were compared to determine if there are changes in sheet geometry at different depths of emplacement. These graphs show
Journal Article
Published: 01 May 2011
Journal of the Geological Society (2011) 168 (3): 689–704.
...Fig. 5. Stereograms of measurement sites around Loch Coruisk, for cone sheets not plotted on the stereogram in Figure 3 a. The sheets dip towards the same focus zone as the other sheets. (See Fig. 4 for location.) ...
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Journal Article
Journal: Geology
Published: 01 March 1999
Geology (1999) 27 (3): 207–210.
...Carsten Schirnick; Paul van den Bogaard; Hans-Ulrich Schmincke Abstract More than 500 trachytic to phonolitic cone sheet dikes, hypabyssal syenite stocks, and subordinate radial dikes form a 20-km-diameter intrusive complex in the volcaniclastic fill of the Miocene Tejeda caldera (20 × 35 km...
Journal Article
Published: 19 September 2024
Geological Magazine (2023) 160 (12): 2147–2165.
...Martin Bromann Klausen; Madelaine R Frazenburg Abstract Both radiating dykes and proximal cone sheets converge onto a positive aeromagnetic anomaly of an inferred carbonatitic centre, hidden beneath a retreating edge of the Frederikshåbs Isblink glacier. This convergence, together with sub-parallel...
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Journal Article
Journal: GSA Bulletin
Published: 01 April 1999
GSA Bulletin (1999) 111 (4): 607–619.
...S. E. Johnson; S. R. Paterson; M. C. Tate Abstract The Cretaceous Zarza Intrusive Complex, located in the Peninsular Ranges of Baja California Norte, Mexico, is perhaps the best-preserved multiple-center, cone-sheet–bearing ring complex documented in North America. The 7 km 2 elliptical complex...
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Dip angles of each cone sheet plotted against distance from the focus zone of the cone sheet swarm. It should be noted that data are widely scattered and there is no specific trend of dip variation with distance.
Published: 01 May 2011
Fig. 8. Dip angles of each cone sheet plotted against distance from the focus zone of the cone sheet swarm. It should be noted that data are widely scattered and there is no specific trend of dip variation with distance.
Journal Article
Published: 01 January 1954
Geological Magazine (1954) 91 (1): 79–85.
...William Trevelyan Harry Abstract "In a Tertiary ring complex at Carlingford, Eire, a large mass of eucrite is cut by porphyritic cone-sheets. A major granophyre intrusion later than the cone-sheets alters the clinopyroxene of the sheets to hornblende whilst the clinopyroxene of the adjacent eucrite...
Series: Geological Society, London, Special Publications
Published: 01 January 2004
DOI: 10.1144/GSL.SP.2004.234.01.08
EISBN: 9781862394827
..., successively, swarms of early mafic enclaves, disrupted synplutonic cone sheets, and late cone-sheets. After the emplacement and subsequent unroofing of the plutonic ring complexes, abundant and thick trachytic pyroclastic flows and falls were emitted from the younger caldera volcanoes, while hawaiite...
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Journal Article
Journal: PALAIOS
Published: 01 December 2008
PALAIOS (2008) 23 (12): 833–847.
..., but rare, very large examples attain 1300 mm in diameter. On bedding planes, individual structures are conspicuously expressed as groups of concentric rings, some of which appear as low ridges (rugae). At least some of these rings correspond to concentric cone sheets (hollow cones) extending downward...
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Journal Article
Published: 01 April 1975
Journal of the Geological Society (1975) 131 (2): 159–161.
... can be important is shown at Carlingford and Skye, where layered gabbros intrude as sheets above sialic crust and at the base of the Tertiary lava pile: Bailey’s mechanism for ring dyke formation is almost impossible here. Dr Walker likened the inclined sheets of Iceland to cone sheets, but the former...
Journal Article
Published: 19 December 2022
Geological Magazine (2023) 160 (2): 305–321.
...Alan G. Marlow; Martin R. Palmer Abstract The Twyfelskupje carbonatite complex, Southern Namibia, exhibits the typical igneous emplacement structures of carbonatites, including plugs, cone sheets and dyke stockworks. The excellent exposure allows for detailed studies of the high-level geochemical...
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Journal Article
Published: 12 January 2015
Geological Magazine (2015) 152 (5): 802–812.
...Figure 5. Model of sequential emplacement of cone sheets as proposed by Lurie (unpub. Ph.D. thesis, Rhodes Univ., 1973) along a W–E section through the centre of the complex. The emplacement order is as proposed by Lurie. Section 1 shows...
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Journal Article
Published: 01 April 1975
Journal of the Geological Society (1975) 131 (2): 121–141.
... in the localisation of igneous intrusions, forms the basis for a new interpretation of the mechanism of formation of the intrusions and enables a model to be developed for the evolution of each centre. Firstly it is postulated that the emplacement of cone sheets is governed by a tendency of rising magma to move...
Journal Article
Published: 01 March 1972
Journal of the Geological Society (1972) 128 (2): 173–205.
... by faults associated with the Kavirondo rift structure, and the trough is partly infilled by Pleistocene sediments. Eastwards, on the fringe of the volcano, the Nyanzian basement is penetrated by the carbonatite cone-sheet complexes of the Ruri Hills, the ijolite-urtite mass of Usaki which is surrounded...