Topic
Gondwana
About: Gondwana is a research topic. Over the lifetime, 6078 publications have been published within this topic receiving 263050 citations. The topic is also known as: Gondwanaland.
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TL;DR: Early Ordovician granites are comparable to those of high-K, calc-alkaline S-type granites and they exhibit negative values of zircon eHf(t) (−8.5 to + 1.7) and whole-rock eNd(t), as well as old zirccon Hf model ages (TCDM = 1349-1992 ǫ and wholerock Nd model ages(TCDM= 1145-1804 ).
85 citations
TL;DR: In this article, a database of over 14,000 dykes mapped in this way for southern Africa allows the geometry of dyke swarms there to be studied with new completeness.
85 citations
TL;DR: In this paper, SHRIMP data obtained from the Urra Formation volcaniclastic rocks indicate an Early Ordovician age ( 206 Pb/ 238 U ages ranging from 494.6±6.8 Ma to 488.3±5.2 Ma) for this magmatic event.
85 citations
TL;DR: This paper proposed a tight fit at 200 Ma for India, Madagascar, Sri Lanka and Antarctica against the east coast of Africa that avoids the difficulty of accounting for the gaps between continents required by looser fits.
85 citations
TL;DR: In this article, the authors reviewed the allochthonous terrane accretion model for the geological development of the Antarctic Peninsula continental margin arc and reinterpreted the geology as having evolved as an in situ continental arc.
Abstract: The allochthonous terrane accretion model previously proposed for the geological development of the Antarctic Peninsula continental margin arc is reviewed in light of recent data and the geology is reinterpreted as having evolved as an in situ continental arc. This is based upon the following factors: (1) the presence of Early Palaeozoic basement and stratigraphic correlation of sequences between the autochthonous and previously proposed allochthonous terranes; (2) isotopic evidence for similar deep crustal structure across the different terranes; (3) ocean island basalt magmas and deep marine sedimentary rocks formed during continental margin extension within the previously proposed accretionary wedge sequence (i.e. not formed against an active oceanic arc); (4) the distribution of magnetic susceptibility measurements and aeromagnetic data locating the palaeo-subduction zone along the west of the Peninsula; (5) a lack of clear palaeomagnetic distinction between the terranes. The following alternative tectonic history is proposed: (1) amalgamation and persistence of Gondwana; (2) subsequent silicic large igneous province magmatism and extension; (3) development and history of Andean subduction until its cessation in the Cenozoic. A number of features in the Antarctic Peninsula correlate with those of other circum-Pacific margins, supporting a global evaluation of allochthonous v. autochthonous margin development to aid our understanding of crustal growth mechanisms.
85 citations