Journal ArticleDOI
Preferential distribution along transcontinental corridors of kimberlites and related rocks of Southern Africa
Hielke Jelsma,Maarten J. de Wit,Christien Thiart,Paul H.G.M. Dirks,Giulio Viola,I.J. Basson,Eva Anckar +6 more
TLDR
In this paper, the emplacement of kimberlites and related rocks in Southern Africa is analyzed using a framework of lineaments defined by combining geology, aeromagnetics, gravity and geomorphological data.Abstract:
Regional and local structural controls on the emplacement of 1326 Southern African kimberlites and related rocks (kimberlites sensu lato, 11% of which are dated) are analysed using a framework of lineaments defined by combining geology, aeromagnetics, gravity and geomorphological data. Spatial analysis of occurrences within clusters of kimberlites less than 100km across resolves variable trends, depending on the age and position of the cluster; but on a regional scale the distribution of these clusters is statistically controlled by four lineament trends: 040°, 096°, 134° and 165°. Similar regional trends are observed as aspect lineaments that can be followed over large distances from modelling the variation in dip direction of the Southern African topography. These observations suggest that different geological parameters exert a control on the distribution of kimberlites. Local structures may include en-echelon fault arrays, Riedel, R’-, P- or T-structures within trans-continental lithosphere structures (cryptic continental corridors). Many cryptic continental corridors are collinear with fracture zones along the Atlantic and Indian continental margins of Southern Africa, and may have found their origin in events resulting from plate reorganization during the break-up of the supercontinent Gondwana. Fault resistance may have rapidly changed the stress state of the African continent causing the deep lithospheric faults to be the loci of episodic extension, allowing kimberlite fluids to ascend through the faults and cluster within near-surface structures. A progressive age variation of kimberlite magmatism in Southern Africa may be attributed to stress propagation along deep lithospheric fractures.read more
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Diamonds sampled by plumes from the core–mantle boundary
Trond H. Torsvik,Trond H. Torsvik,Kevin Burke,Kevin Burke,Bernhard Steinberger,Bernhard Steinberger,Susan J. Webb,Lewis D. Ashwal +7 more
TL;DR: Torsvik et al. as mentioned in this paper used a plate-tectonic reconstruction for the past 540 million years to locate the positions of these cratons relative to the deep mantle at times when kimberlites were erupted.
Journal ArticleDOI
Tectonic setting of kimberlites
TL;DR: Kimberlite ages span the assembly and break-up of a number of supercontinents, such as Rodinia and Gondwana as mentioned in this paper, and their distribution illustrates clustering in time and space.
Journal ArticleDOI
Diamonds through Time
TL;DR: The oldest prolific smooth-surfaced crystalline diamond formation event documented on the world’s major diamond producing cratons occurs in Archean lithospheric mantle harzburgite, metasomatized by likely subduction-related potassic carbonatitic fluids as mentioned in this paper.
Journal ArticleDOI
Mesozoic exhumation of the southern Cape, South Africa, quantified using apatite fission track thermochronology
TL;DR: In this paper, the authors quantified the timing and extent of exhumation across the southern Cape escarpment and coastal plane, using apatite fission track analysis (AFTA) of 25 outcrop samples and 31 samples from three deep boreholes (KW1/67, SA1/66, CR1/68).
References
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TL;DR: In this article, the formation and evolution of Kimberlite Magmatism and Genetic Classifications are discussed, as well as the properties of the Kimberlite fields and Provinces: their Tectonic Setting.
Journal ArticleDOI
Intraplate seismicity, reactivation of preexisting zones of weakness, alkaline magmatism, and other tectonism postdating continental fragmentation
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Related Papers (5)
Geochemistry of South African On- and Off-craton, Group I and Group II Kimberlites: Petrogenesis and Source Region Evolution
Megan Becker,Anton P. le Roex +1 more