Karoo igneous activity, and the early stages of the break-up of Gondwanaland

Cox, K. G.

doi:10.1144/gsl.sp.1992.068.01.09

Cited by 151 publications

(130 citation statements)

References 22 publications

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“…This has been postulated in almost all published models [Martin and Hartnady, 1986;Kristoffersen and Haugland, 1986;Lawver et al, 1991;Cox, 1992;Elliot, 1992;Grunow, 1993b;Livermore and Hunter, 1996]. We used the Beattie Anomaly ( Figure 7a) and a strong magnetic anomaly along the Heimefrontfjella (SKA-Sverdrupfjella-KirvanveggenAnomaly; Golynsky and Aleshkova, 2000) as starting point for our model.…”

Section: Epmmentioning

confidence: 96%

Timing and geometry of early Gondwana breakup

et al. 2003

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[1] The Mesozoic opening history of the Southern Ocean between South America, Africa, and Antarctica is one of the largest gaps in knowledge on the evolution of this region. Competing geodynamic models were published during the last two decades to explain the geophysical and geological observations. Here we report on aeromagnetic data collected along the East Antarctic coast during five seasons. These data provide new constraints on the timing and geometry of the early Gondwana breakup. In the Riiser-Larsen Sea/ Mozambique Basin, the first oceanic crust between Africa and Antarctica formed around 155 Ma. In the west the Weddell Rift propagated from west to east with a velocity of 63 km/Myr between chrons M19N and M17N. At chron M14N, South America and Africa finally were split off the Antarctic continent. Stretching in the area of the South Atlantic started at the latest from 155 Myr onward. The different spreading velocities and directions of South America and Africa created at chron M9N the first oceanic crust in the South Atlantic. A new model indicates that the Karoo and Dronning Maud Land magmatism occurred well before any new ocean floor was created and therefore the first formation of new oceanic crust cannot directly be related to a plume interaction.

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Section: Epmmentioning

confidence: 96%

Timing and geometry of early Gondwana breakup

et al. 2003

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“…3). These are capped by some 1.4 km of basaltic lavas of the Drakensberg Group (Veevers et al, 1994;Johnson et al, 1996), the extrusion of which is related to the break-up of Gondwana (Cox, 1992).…”

Section: General Geology and Stratigraphy Of The Karoo Supergroupmentioning

confidence: 99%

South Africa's coalfields — A 2014 perspective

Hancox

Götz

2014

International Journal of Coal Geology

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Highlights• South Africa's Coalfields are presented.• The role of Gondwanan coals as palaeoclimate archives is stated.• Future research fields include palynology, sequence stratigraphy, basin fill. AbstractFor well over a century and a half coal has played a vital role in South Africa's economy and currently bituminous coal is the primary energy source for domestic electricity generation, as well as being the feedstock for the production of a substantial percentage of the country's liquid fuels. It furthermore provides a considerable source of foreign revenue from exports.Based on geographic considerations, and variations in the sedimentation, origin, formation, distribution and quality of the coals, 19 coalfields are generally recognised in South Africa. This paper provides an updated review of their exploration and exploitation histories, general geology, and coal seam nomenclature and coal qualities. Within the various coalfields autocyclic variability is the norm rather than the exception, whereas allocyclic variability is much less so, and allows for the correlation of genetically related sequences. During the mid-Jurassic break up of Gondwana most of the coals bearing successions were intruded by dolerite. These intrusions are important as they may cause devolatilisation and burning of the coal, create structural disturbances and related seam correlation problems, and difficulties in mining operations.Whilst many of the coalfields have been extensively explored and exploited, those in the north of the country have until recently received much less attention. Four coalfields occur partly or wholly within the Limpopo Province of South Africa and these may contain as much as 70% of South Africa's remaining coal resources. These coalfields in particular have been the focus of recent exploration due to the presence of large coking and thermal coal resources, as well as for their coal bed methane potential, resources that need to be unlocked regards to maximum benefit and minimal environmental degradation. South Africa's coals have been also recently addressed as palaeoclimate archives recording Gondwana's postglacial climate amelioration by major changes in land plant communities, and proving high-resolution palyno-stratigraphy as a crucial tool to decipher climate change during the Permo-Carboniferous. This aspect of the coals of South Africa is also reviewed.

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“…They show a temporal relationship to continental plate break-up, and particularly characterise the Jurassic-Cretaceous break-up history of Gondwana (e.g. Karoo, Parana-Etendeka continental flood basalts, Ferrar Group and oceanic plateaux: OntongJava, Kerguelen, Manihiki; Coffin and Eldholm, 1994 and references therein; Elliot, 1992;Cox, 1992). Emplacement of continental flood basalt provinces typically occurs over time scales of 10 5 -10 6 years (Coffin and Eldholm, 1994).…”

Section: Introductionmentioning

confidence: 99%

The Whitsunday Volcanic Province, Central Queensland, Australia: lithological and stratigraphic investigations of a silicic-dominated large igneous province

Bryan

Ewart

Stephens³

et al. 2000

Journal of Volcanology and Geothermal Research

100

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Contrary to general belief, not all large igneous provinces (LIPs) are characterised by rocks of basaltic composition. Silicicdominated LIPs, such as the Whitsunday Volcanic Province of NE Australia, are being increasingly recognised in the rock record. These silicic LIPs are consistent in being: (1) volumetrically dominated by ignimbrite; (2) active over prolonged periods (40-50 m.y.), based on available age data; and (3) spatially and temporally associated with plate break-up. This silicicdominated LIP, related to the break-up of eastern continental Gondwana, is also significant for being the source of Ͼ 1:4 × 10 6 km 3 of coeval volcanogenic sediment preserved in adjacent sedimentary basins of eastern Australia. The Whitsunday Volcanic Province is volumetrically dominated by medium-to high-grade, dacitic to rhyolitic lithic ignimbrites. Individual ignimbrite units are commonly between 10 and 100 m thick, and the ignimbrite-dominated sequences exceed 1 km in thickness. Coarse lithic lag breccias containing clasts up to 6 m diameter are associated with the ignimbrites in proximal sections. Pyroclastic surge and fallout deposits, subordinate basaltic to rhyolitic lavas, phreatomagmatic deposits, and locally significant thicknesses of coarse-grained volcanogenic conglomerate and sandstone are interbedded with the ignimbrites. The volcanic sequences are intruded by gabbro/dolerite to rhyolite dykes (up to 50 m in width), sills and comagmatic granite. Dyke orientations are primarily from NW to NNE.The volcanic sequences are characterised by the interstratification of proximal/near-vent lithofacies such as rhyolite domes and lavas, and basaltic agglomerate, with medial to distal facies of ignimbrite. The burial of these near-vent lithofacies by ignimbrites, coupled with the paucity of mass wastage products such as debris-flow deposits indicates a low-relief depositional environment. Furthermore, the volcanic succession records a temporal change in: (1) eruptive styles; (2) the nature of source vents; and (3) erupted compositions. An early explosive dacitic pyroclastic phase was succeeded by a later mixed pyroclasticeffusive phase producing an essentially bimodal suite of lavas and rhyolitic ignimbrite. volcanic lithofacies, the volcanic sequences are interpreted to record the evolution of a multiple vent, low-relief volcanic region, dominated by several large caldera centres. ᭧

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Karoo igneous activity, and the early stages of the break-up of Gondwanaland

Cited by 151 publications

References 22 publications

Timing and geometry of early Gondwana breakup

Timing and geometry of early Gondwana breakup

South Africa's coalfields — A 2014 perspective

The Whitsunday Volcanic Province, Central Queensland, Australia: lithological and stratigraphic investigations of a silicic-dominated large igneous province

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