@inbook{56ae970e4de94a9581c9a0a4eeefd0b7,
title = "Constraining the chronology of the mashishing dykes from the eastern kaapvaal craton in South Africa",
abstract = "The present study focuses on NNE-trending dykes (sites LDA to LDJ) that occur near Mashishing in the eastern Kaapvaal craton. The Mashishing dykes were previously considered to be coeval and regarded as the extension of the 1.875–1.835{\^A} Ga Black Hills dyke swarm into the sedimentary rocks of the Pretoria Group. Thin sections exhibit well-preserved igneous textures, with primary minerals (e.g., hornblende, clinopyroxene, plagioclase) extensively altered to secondary minerals in most cases. Our dykes can be petrographically grouped as pyroxenite (LDB and LDC), dolerite (LDH) and diorite (remainder of samples). REE and multi-element profiles of pyroxenites and two of the diorites (LDI and LDJ) suggest a common origin of the four dykes, but show no similarity with known mafic units of the Kaapvaal craton. An age estimate between 2208 and 2276{\^A} Ma for dyke LDB, obtained from two overlapping amphibole 40Ar/39Ar plateau results, indicates that these four dykes predates the ~2.05{\^A} Ga Bushveld event. The six remaining dykes have similar chemistry to either the ~2.06{\^A} Ga Dullstroom Lavas (LDG), the 1.875–1.835{\^A} Ga Black Hills dyke swarm (LDH) or the ~1.11{\^A} Ga Umkondo dolerites (LDA, LDD, LDE and LDF). An U–Pb baddeleyite date of 1867 ± 10{\^A} Ma for dyke LDH confirms it as a member of the Black Hills dyke swarm. Demagnetization of eighty-three specimens reveals five stable magnetizations carried by titanomagnetite. Two of these are regarded as magnetic overprints while three magnetizations are likely representative of primary remanences. The corresponding virtual geomagnetic poles (Lat.−26.84°N, Long. 31.66°E; Lat. 26.07°N, Long. 11.01°E, and Lat. 55.84°N, Long. 65.02°E) resemble those from the ~2.23{\^A} Ga Hekpoort Formation, the ~1.88–1.83{\^A} Ga post-Waterberg intrusions, and the ~1.11{\^A} Ga Umkondo dolerites respectively. The above results suggest that the Mashishing dykes, despite similar trends, constitute swarms of different generations.",
keywords = "Geochemistry, Geochronology, Kaapvaal craton, NNE-dyke, Paleomagnetism",
author = "H. Wabo and F. Humbert and {de Kock}, {M. O.} and G. Belyanin and U. S{\"o}derlund and Mar{\'e}, {L. P.} and Beukes, {N. J.}",
note = "Publisher Copyright: {\textcopyright} Springer Nature Singapore Pte Ltd. 2019.",
year = "2019",
doi = "10.1007/978-981-13-1666-1_6",
language = "English",
series = "Springer Geology",
publisher = "Springer",
pages = "215--261",
booktitle = "Springer Geology",
address = "Germany",
}