Multistage Evolution of Dolerites in the Karoo Large Igneous
                    Province, Central South Africa

Neumann, Else-Ragnhild; Svensen, Henrik; Galerne, Christophe; Planke, Sverre

doi:10.1093/petrology/egr011

Cited by 121 publications

(61 citation statements)

References 77 publications

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“…3b) generally ascribed to significant contribution from the underlying Precambrian basement and SCLM (e.g., Ellam 2006;Ellam andCox 1989, 1991;Harris et al 1990;Hawkesworth et al 1984;Jourdan et al 2007a;Luttinen and Furnes 2000;Luttinen et al 1998;Sweeney et al 1991Sweeney et al , 1994Neumann et al 2011). They have traditionally been divided into low-Ti and high-Ti provinces (e.g., Cox 1988;Sweeney et al 1994), but the geochemical and geochronological data are more compatible with a division into (1) ~182 Ma plateau-assemblage CFBs composed of relatively monotonous and widespread low-Ti tholeiites and (2) ~190-174 Ma rift-assemblage CFBs composed of diverse low-Ti and high-Ti basalts and picrites sandwiched between nephelinites and felsic volcanic rocks in the main triple rift ( Fig.…”

Section: Geological Settingmentioning

confidence: 99%

Enriched continental flood basalts from depleted mantle melts: modeling the lithospheric contamination of Karoo lavas from Antarctica

Heinonen

Luttinen

Bohrson

2015

Contrib Mineral Petrol

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and partial melting of crustal wall rock and (2) assimilationfractional crystallization equations for lithospheric mantle contamination by using highly alkaline continental volcanic rocks (i.e., partial melts of mantle lithosphere) as contaminants. Calculations indicate that the different magma types can be produced by just minor (1-15 wt%) contamination of asthenospheric parental magmas by melts from variable lithospheric reservoirs. Our models imply that the role of continental lithosphere as a CFB source component or contaminant may have been overestimated in many cases. Thus, CFBs may represent major juvenile crustal growth events rather than just recycling of old lithospheric materials.

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Section: Geological Settingmentioning

confidence: 99%

Enriched continental flood basalts from depleted mantle melts: modeling the lithospheric contamination of Karoo lavas from Antarctica

Heinonen

Luttinen

Bohrson

2015

Contrib Mineral Petrol

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“…7a; Neumann et al 2011 (Fig. 3), the GVS and GS showed identical Sr-Nd isotope ratios, confirming derivation from the same (or identical) magma batches.…”

Section: Methodsmentioning

confidence: 53%

“…7 a Variations in initial Sr-Nd isotopes among the GVSC units (after Neumann et al 2011), assuming the age of 183 Ma determined for sills in the Karoo Basin (Svensen et al 2007(Svensen et al , 2012. The trend is estimated on the basis of the EC-RAFC model of Spera and Bohrson (2004) using dyke SA.20.1 from southern KwaZuluNatal, South Africa (Riley et al 2006) as initial-melt model and a combination of the Proterozoic mafic granulite xenoliths HCA28 and HCA35 from the northern Lesotho/central Cape province (Huang et al 1995).…”

Section: Methodsmentioning

confidence: 99%

“…Based on major and trace element and Sr-Nd isotope data Neumann et al (2011) concluded that the different geochemical signatures in the different units in the Golden Valley Sill Complex were caused by a combination of interaction with the lithospheric mantle and fractional crystallization and contamination in the deep crust. The ascending magmas lost their buoyancy when passing from the dense upper mantle into the less dense lower crust, and ponded there.…”

Section: Genetic Relationship and Evolutionary Historymentioning

confidence: 99%

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Geochemical Fingerprinting and Magmatic Plumbing Systems

Galerne

Neumann

2014

Physical Geology of Shallow Magmatic Systems

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Subvolcanic systems are characterized by complex combinations of intrusive units (dykes, sills, saucer-shaped sills, cone sheets, etc.) for which genetic relationships are unclear. This chapter explains how whole-rock geochemistry may be used to resolve the genetic relationships of such subvolcanic (and volcanic) systems. We start with a short introduction of the geochemical fingerprinting method with particular emphasis on the statistical refinement method called Forward Stepwise-Discriminant Function Analysis (FS-DFA). Combined with field mapping and structural analysis, geochemical fingerprinting based on major and trace elements and isotope ratios, is a very powerful tool to distinguish between igneous units (lavas, sills, dykes) with subtle (or not so subtle) geochemical differences. Different geochemical fingerprinting or signatures indicate derivation from distinct magma batches. The results from FS-DFA analyses may be used to reveal genetic relationships between geological units, or lack of such, which again may be used to throw light on subvolcanic plumbing systems, the feeding system in sill-dyke complexes, as well as other problems. The method is illustrated by studies of the Golden Valley Sill Complex in the Karoo Basin (South Africa).

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“…Sills are absent in the Drakensberg Group lavas, suggesting that they were emplaced prior to the main phase of flood volcanism or that emplacement within the lavas was prevented. The Karoo sills are dominantly tholeiitic basalts to basaltic andesites, although more evolved sills are also present locally (Marsh and Eales 1984;Neumann et al 2011). Recently published U-Pb zircon data (Svensen et al 2012) indicate that basin-scale emplacement took place within an interval of less than 0.5 Ma and could represent a single magma emplacement event.…”

Section: Geological Settingmentioning

confidence: 99%

Geothermal energy from the Main Karoo Basin? New insights from borehole KWV-1 (Eastern Cape, South Africa)

2016

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Multistage Evolution of Dolerites in the Karoo Large Igneous Province, Central South Africa

Cited by 121 publications

References 77 publications

Enriched continental flood basalts from depleted mantle melts: modeling the lithospheric contamination of Karoo lavas from Antarctica

Enriched continental flood basalts from depleted mantle melts: modeling the lithospheric contamination of Karoo lavas from Antarctica

Geochemical Fingerprinting and Magmatic Plumbing Systems

Geothermal energy from the Main Karoo Basin? New insights from borehole KWV-1 (Eastern Cape, South Africa)

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