Volcanological features of a low-viscosity melt: the carbonatitic Gross Brukkaros Volcanic Field, Namibia

Kurszlaukis, S.; Lorenz, Volker

doi:10.1007/s004450050150

Cited by 23 publications

(6 citation statements)

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“…Kurszlaukis et al (1998b) and Kurszlaukis and Lorenz (2000) describe a distinct elongation of many kimberlite pipes parallel to pre-existing faults and joints within the country rock of the Gibeon Kimberlite Field. Kurszlaukis and Lorenz (1996) also report a direct control of the stress field on the shapes of diatremes surrounding Gross Brukkaros, a carbonatitic dome structure in southern Namibia. Zhang et al (1989) and Dobbs et al (1994) describe a close structural control on the location Volcanological and structural aspects of the Venetia kimberlite cluster -a case study of South African kimberlite maar-diatreme volcanoes and outline of highly eroded pipes in the Shangdong Province, China.…”

Section: Introductionmentioning

confidence: 96%

Volcanological and structural aspects of the Venetia kimberlite cluster - a case study of South African kimberlite maar-diatreme volcanoes

Kurszlaukis

Barnett

2003

South African Journal of Geology

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The paper summarises an investigation of the volcanology of the Venetia kimberlite cluster and the country rock structures in the immediate vicinity of the pipes. Our study shows that the pre-existing country rock structure and the stress field prevailing during emplacement control the position and morphology of the pipes. The pipes were formed along pre-existing zones of weakness, and the pipe shapes are elongated in the direction of fractures and faults. The highest degree of vertical and lateral pipe shape irregularity is found in the vicinity of country rock structural weaknesses. The understanding of this relationship between pipe geometry and country rock structure can significantly affect mineral resource models.The most important volcanological feature of the cluster is the presence of bedded fragmental rocks filling the main pipes K1 and K2. These rocks are readily interpreted as volcaniclastic in origin, yet are petrographically identified as typical Southern African tuffisitic kimberlite breccias ("TKB"). These observations contradict the hypothesis that "TKB's" are intrusive rocks, which are expected to be massive and unstructured in nature.The presence of accretionary (armoured) lapilli, soft sediment deformation, and signs of reworking within the volcaniclastic deposits suggest a high moisture content of the volcaniclastic material during and after emplacement of the pipe. Monolithic talus fans as well as contact breccias represent significant facies types within the Venetia kimberlite cluster. The contact breccias show signs of downward movement along the pipe walls, suggesting a considerable volume deficit at depth. These volcanological observations need to be accounted for in a comprehensive emplacement model for the Venetia kimberlite pipes.The observed structures, internal textures and facies suggest that the Venetia pipes were emplaced in several violent volcanic phases, separated by periods of relative inactivity.

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Section: Introductionmentioning

confidence: 96%

Volcanological and structural aspects of the Venetia kimberlite cluster - a case study of South African kimberlite maar-diatreme volcanoes

Kurszlaukis

Barnett

2003

South African Journal of Geology

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“…Clement, 1973;Dawson, 1980;Clement and Skinner, 1985;Mitchell, 1986;Keller, 1989;Dawson et al, 1992;Stoppa and Lavecchia, 1992;Stoppa and Lupini, 1993;Mitchell, 1995;Stachel et al, 1994;Stoppa, 1996;Stoppa and Principe, 1998;Kurszlaukis and Lorenz, 1997;Lorenz and Kurszlaukis, 1997;Stoppa and Woolley, 1997). In contrast with frozen droplets, the spinning droplets show a dense, oriented microphenocrysts fabric.…”

Section: Discussionmentioning

confidence: 90%

Kamafugitic diatremes: their textures and field relationships with examples from the Goiás alkaline province, Brazil

Junqueira-Brod

Gaspar

Brod

et al. 2005

Journal of South American Earth Sciences

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“…This creates a deep pipe resulting from a series of sub-Plinian to Plinian eruptions (Field and Scott Smith 1999;Sparks et al 2006;Porritt et al 2008). The second model involves diatreme excavation during phreatomagmatic eruptions as magma propagating to the surface encounters water (Lorenz 1985; Kurszlaukis and Lorenz 1997;Kurszlaukis et al 1998;Lorenz and Kurszlaukis 2007;Brown et al 2008a).…”

Section: U N C O R R E C T E D P R O O Fmentioning

confidence: 99%

“…In addition, maar-diatremes, although the second most common type of volcano (Lorenz 1985;Cas and Wright 1988;Lorenz 2007), tend to be eroded and poorly preserved in older sequences. In rare cases, exposures of the lower diatreme zone enables detailed investigation of the internal architecture and structure of the system (e.g., Francis (1970), Hawthorne (1975), Kurszlaukis and Lorenz (1997), Davies et al (2008), Gernon et al (2013), Lefebvre et al (2013), and Mundula et al (2013)) or preservation of extra-crater tephra deposits allow…”

Section: U N C O R R E C T E D P R O O F Introductionmentioning

confidence: 99%

Basaltic maar-diatreme volcanism in the Lower Carboniferous of the Limerick Basin (SW Ireland)

et al. 2015

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Lead-zinc exploration drilling within the Limer-7 ick Basin (Southern Ireland) has revealed the deep inter-8 nal architecture and extra-crater deposits of five alkali-9 basaltic maar-diatremes. These were emplaced as part of 10 a regional northeast southwest tectonomagmatic trend 11 during the Lower Carboniferous Period. Field relation-12 ships and textural observations suggest that the diatremes 13 erupted into a shallow submarine environment. Limerick 14 trace element data indicates a genetic relationship between 15 the diatremes and extra-crater successions of the Knock-16 roe Formation, which records multiple diatreme filling 17 and emptying cycles. Deposition was controlled largely 18 by bathymetry defined by the surrounding Waulsortian 19 carbonate mounds. An initial non-diatreme forming erup-20 tion stage occurred at the water-sediment interface, with 21 magma-water interaction prevented by high magma ascent 22 rates. This was followed by seawater incursion and the 23 onset of phreatomagmatic activity. Magma-water interac-24 tion generated poorly vesicular blocky clasts, although the 25 co-occurrence of plastically deformed and highly vesicular 26 clasts indicates that phreatomagmatic and magmatic pro-27 cesses were not mutually exclusive. At a later stage, the 28 diatreme filled with a slurry of juvenile lapilli and coun-29 try rock lithic clasts, homogenised by the action of debris Q1 30

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Volcanological features of a low-viscosity melt: the carbonatitic Gross Brukkaros Volcanic Field, Namibia

Cited by 23 publications

References 22 publications

Volcanological and structural aspects of the Venetia kimberlite cluster - a case study of South African kimberlite maar-diatreme volcanoes

Volcanological and structural aspects of the Venetia kimberlite cluster - a case study of South African kimberlite maar-diatreme volcanoes

Kamafugitic diatremes: their textures and field relationships with examples from the Goiás alkaline province, Brazil

Basaltic maar-diatreme volcanism in the Lower Carboniferous of the Limerick Basin (SW Ireland)

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