A review of the stratigraphy and sedimentary environments of the Karoo-aged basins of Southern Africa

Smith, Roger M. H.; Eriksson, P.G.; Botha, W. J.

doi:10.1016/0899-5362(93)90164-l

Cited by 178 publications

(119 citation statements)

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“…As the geological evidence of burrow formation goes back nearly 540 million years, as shown from trace fossil evidence in rocks of Early Cambrian age (Mcilroy and Heys, 1997), burrow collapse as a mechanism of seismic mortality should date back at least this far. The distant ancestors of all mammals (synapsids) who survived the Permian/Triassic mass extinction 250 million years ago were apparently burrowing animals living along the tectonically active margin of the ancient supercontinent of Gondwanaland (Smith et al, 1993). Their fossil remains are almost always found as pairs of animals in collapsed burrows (Smith et al, 1993;Smith, personal comm., 1997).…”

Section: Discussionmentioning

confidence: 99%

“…The distant ancestors of all mammals (synapsids) who survived the Permian/Triassic mass extinction 250 million years ago were apparently burrowing animals living along the tectonically active margin of the ancient supercontinent of Gondwanaland (Smith et al, 1993). Their fossil remains are almost always found as pairs of animals in collapsed burrows (Smith et al, 1993;Smith, personal comm., 1997). Thus, mammals in particular have had over 250 million years in which to refine their seismicescape response and link it via exaptation to additional sensory signals.…”

Section: Discussionmentioning

confidence: 99%

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Earthquake Prediction by Animals: Evolution and Sensory Perception

Kirschvink¹

2000

Bulletin of the Seismological Society of America

105

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Animals living within seismically active regions are subjected episodically to intense ground shaking that can kill individuals through burrow collapse, egg destruction, and tsunami action. Although anecdotal and retrospective reports of animal behavior suggest that although many organisms may be able to detect an impending seismic event, no plausible scenario has been presented yet through which accounts for the evolution of such behaviors. The evolutionary mechanism of exaptation can do this in a two-step process. The first step is to evolve a vibrationtriggered early warning response which would act in the short time interval between the arrival of P and S waves. Anecdotal evidence suggests this response already exists. Then if precursory stimuli also exist, similar evolutionary processes can link an animal's perception of these stimuli to its P-wave triggered response, yielding an earthquake predictive behavior. A population-genetic model indicates that such a seismic-escape response system can be maintained against random mutations as a result of episodic selection that operates with time scales comparable to that of strong seismic events. Hence, additional understanding of possible earthquake precursors that are presently outside the realm of seismology might be gleaned from the study of animal behavior, sensory physiology, and genetics. A brief review of possible seismic precursors suggests that tilt, hygroreception (humidity), electric, and magnetic sensory systems in animals could be linked into a seismic escape behavioral system. Several testable predictions of this analysis are discussed, and it is recommended that additional magnetic, electrical, tilt, and hygro-sensors be incorporated into dense monitoring networks in seismically active regions.

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Section: Discussionmentioning

confidence: 99%

Section: Discussionmentioning

confidence: 99%

Earthquake Prediction by Animals: Evolution and Sensory Perception

Kirschvink¹

2000

Bulletin of the Seismological Society of America

105

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“…Botha, 1968;Le Roux, 1974;Johnson, 1976;Visser and Botha, 1980;Eriksson, 1983Eriksson, , 1985Kitching and Raath, 1984;Smith et al, 1993;Johnson et al, 1996;Johnson et al, 1997;Smith and Kitching, 1997) few field-based geological investigations dealing with the stratigraphy, sedimentology, depositional environments and basin development had been undertaken prior to the various works of Bordy et al (2004 a-d).…”

Section: Elliot Formationmentioning

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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“…In addition, it serves as a datum for classifying Karoo basins in central and southern Africa. The bulk of the Karoo strata occur in the Main Karoo Basin, with maximum preserved thickness adjacent to the Cape Fold Belt in excess of 6 km [34]. The basin covers up to 700, 000 km 2 and represents about 110 Ma of sedimentation spanning from 290 Ma to 180 Ma, and has its rocks covering almost half of the area of South Africa [35].…”

Section: General Geology and Stratigraphymentioning

confidence: 99%

Geochemistry of sandstones and shales from the Ecca Group, Karoo Supergroup, in the Eastern Cape Province of South Africa: Implications for provenance, weathering and tectonic setting

2017

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Geochemical compositions of twenty-four sandstone and shale samples from the Ecca Group were analysed to decipher their provenance, paleoweathering conditions and tectonic setting. The shales have high Fe 2 O 3 , K 2 O, TiO 2 , Ce, Cu, Ga, La, Nb, Nd, Rb, Sc, Sr, Th and Y content more than the sandstones, whereas, sandstones are higher in SiO 2 , Hf and Zr than the shales. The positive correlations of Al 2 O 3 with other elements as well as the abundance of Ba, Ce, Th, Rb, Zn and Zr suggest that these elements are primarily controlled by the dominant clay minerals. Tectonic discrimination diagrams revealed that the sandstones and shales are mostly of quartzose sedimentary provenance, suggesting that they were derived from a cratonic interior or recycled orogen. The binary plots of TiO 2 versus Ni, TiO 2 against Zr and La/Th versus Hf as well as the ternary diagrams of V-Ni-Th*10 indicate that the shales and sandstones were derived from felsic igneous rocks. A-CN-K (Al 2 O 3 -CaO-K 2 O) ternary diagram and indices of weathering (CIA, CIW and PIS) suggest that the granitic source rocks underwent moderate to high degree of chemical weathering. The CIA values range between 24.41% and 83.76%, indicating low to high weathering conditions. The CIW values for the studied sandstones and shales range from 25.90 to 96.25%, suggesting moderate to high intensive chemical weathering. ICV values for the sandstones and shales vary from 0.71 to 3.6 (averaging 1.20) and 0.41 to 1.05 (averaging 0.82), respectively. The K 2 O/Na 2 O ratios for the studied samples vary from 0.71 to 8.29, which reveal moderate to high maturity. The plot of CIA against ICV shows that most of the shales are geochemically mature and were derived from both weak and intensively weathered source rocks. The tectonic setting discrimination diagrams support passive-active continental margin setting of the provenance.

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A review of the stratigraphy and sedimentary environments of the Karoo-aged basins of Southern Africa

Cited by 178 publications

References 12 publications

Earthquake Prediction by Animals: Evolution and Sensory Perception

Earthquake Prediction by Animals: Evolution and Sensory Perception

South Africa's coalfields — A 2014 perspective

Geochemistry of sandstones and shales from the Ecca Group, Karoo Supergroup, in the Eastern Cape Province of South Africa: Implications for provenance, weathering and tectonic setting

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