Paleo-Mesoproterozoic Assemblages of Continents: Paleomagnetic Evidence for Near Equatorial Supercontinents
| Autor: | L. J. Pesonen, S. Mertanen |
|---|---|
| Rok vydání: | 2012 |
| Předmět: |
geography
geography.geographical_feature_category 010504 meteorology & atmospheric sciences Proterozoic Yilgarn Craton 010502 geochemistry & geophysics 01 natural sciences Supercontinent Dharwar Craton Paleontology Craton Rodinia Laurentia Baltica Geology 0105 earth and related environmental sciences |
| Zdroj: | From the Earth's Core to Outer Space ISBN: 9783642255496 |
| DOI: | 10.1007/978-3-642-25550-2_2 |
| Popis: | Various geological and geophysical evidence show that at least two supercontinents, Nuna and Rodinia existed during the Paleoproterozoic and Mesoproterozoic eras. In this paper we have used updated paleomagnetic and isotope age data during 2.45–1.04 Ga to define the amalgamation and breakup times of these supercontinents. The Nuna and Rodinia supercontinents were predominantly at moderate to low paleolatitudes except during the earliest Paleoproterozoic when some of the continents, notably India (Dharwar craton) and Australia (Yilgarn craton), occupied polar latitudes. Sedimentological indicators of paleoclimate are generally consistent with the paleomagnetic latitudes, with the exception of the Early Proterozoic, when low latitude glaciations took place on several continents. The new data suggest that the Nuna supercontinent started to form at about 1.8 Ga, but the final amalgamation took place as late as ca. 1.53 Ga. The orogenic belts formed within Nuna resulted from a complex set of collisions, rotations and strike slip faultings of the docking cratons. Notably, continuation of 1.8–1.5 Ga accretional belts from Laurentia to Baltica is supported by paleomagnetic data. However, the position of Amazonia in the Laurentia-Baltica unity is still controversal. The occurrence of coeval accretional belts in Amazonia and Baltica and the occurrence of ca. 1.53 Ga rapakivi intrusions in a belt from Baltica to Amazonia support their unity, but the strict paleomagnetic data keeps them separated at 1.53 Ga. Nuna began to break up after 1.2 Ga during several rifting episodes, followed by a short period of independent drift of most of the continents. The amalgamation of Rodinia took place during the period of 1.10–1.04 Ga when most of the Earth’s continents were fused together. |
| Databáze: | OpenAIRE |
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