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: In this article, new zircon U-Pb age data and geochemistry for the Sa9al metamorphic complex (SMC) in Sinai (Egypt) provide the first robust evidence of latest Mesoproterozoic island arc rocks at the northernmost Arabian-Nubian Shield, possibly indicating that formation of the shield commenced prior to 870 Ma.
Abstract: New zircon U-Pb age data and geochemistry for the Sa9al metamorphic complex (SMC) in Sinai (Egypt) provide the first robust evidence of latest Mesoproterozoic island arc rocks at the northernmost Arabian-Nubian Shield, possibly indicating that formation of the shield commenced prior to 870 Ma. An older series of calc-alkaline volcanic and intrusive rocks yielded ages of ca. 1.03–1.02 Ga. Zircon xenocrysts within these rocks attest to arc magmatism predating the SMC by ∼80 m.y., as well as the minor contribution of Paleoproterozoic crust. Detrital zircons of the SMC pelites exhibit textural and U-Pb age patterns supporting their derivation from the volcanic rocks as arc detritus. A ca. 820 Ma gneissic pluton intruding the SMC indicates that by Cryogenian time, the SMC was already incorporated within the evolving Arabian-Nubian Shield. The 1.0–1.1 Ga SMC rocks provide a possible connection between latest Mesoproterozoic ocean closure during the assembly of Rodinia and the later buildup of Gondwana. There is growing indication, including the findings of this study, that 1.0–1.1 Ga crust composed a more significant component in northernmost Gondwana than hitherto recognized.
116 citations
TL;DR: The relationship between multi-million year periods of glaciation (glacio-epochs) over the last 3 Ga of Earth history and phases of supercontinent breakup and assembly is discussed in this article.
116 citations
TL;DR: In the early Ordovician, three main continents are recognized by faunas in Europe, Laurentia (northwest of the closed suture of the Iapetus Ocean), Baltica (north of the general area of the Trans‐European Suture Zone), which was temperate; and Gondwana (south of the TESZ) which was high latitude.
Abstract: In the early Ordovician three main continents are recognized by faunas in Europe, Laurentia (northwest of the closed suture of the Iapetus Ocean), which was tropical; Baltica (north of the general area of the Trans‐European Suture Zone), which was temperate; and Gondwana (south of the TESZ), which was high latitude. As the Ordovician progressed, various terranes separated and drifted away from the Gondwana supercontinent at different times, namely Avalonia (which was probably originally part of Gondwana near South America), Iberia–Armorica, Perunica (Bohemia) and various Alpine fragments. Each terrane developed progressively different faunas as time went by. Avalonia collided with Baltica near the end of Ordovician, confirmed by faunas, tectonics and palaeomagnetism, and subsequently Avalonia–Baltica collided with Laurentia to form Laurussia from the mid‐Silurian to the early Devonian. The Ibero‐Armorica, Perunica and Alpine terranes did not join the European collage until the Devonian. The modern sites of the terrane boundaries bear little direct relationships to the original palaeogeographical boundaries in the Early Palaeozoic.
116 citations
TL;DR: In this paper, the authors provide a new, high-quality, well-dated paleomagnetic pole from the ca. 180 Ma Sangri Group volcanic rocks of the Lhasa terrane that yields a paleolatitude of 3.7°S ± 3.4°.
Abstract: The Mesozoic plate tectonic history of Gondwana-derived crustal blocks of the Tibetan Plateau is hotly debated, but so far, paleomagnetic constraints quantifying their paleolatitude drift history remain sparse. Here, we compile existing data published mainly in Chinese literature and provide a new, high-quality, well-dated paleomagnetic pole from the ca. 180 Ma Sangri Group volcanic rocks of the Lhasa terrane that yields a paleolatitude of 3.7°S ± 3.4°. This new pole confirms a trend in the data that suggests that Lhasa drifted away from Gondwana in Late Triassic time, instead of Permian time as widely perceived. A total northward drift of ∼4500 km between ca. 220 and ca. 130 Ma yields an average south-north plate motion rate of 5 cm/yr. Our results are consistent with either an Indian or an Australian provenance of Lhasa.
116 citations
TL;DR: In this article, the Aldan Shield of Siberia as a continuation of the Wyoming Province of Laurentia has been largely abandoned in favor of models connecting Siberia to northern Laurentia, but it remains controversial which part of Siberia is contiguous with northern Canada and also at issue is the western Laurentia-Australia-East Antarctica connection.
116 citations