首页 | 本学科首页   官方微博 | 高级检索  
     检索      


Gondwana from top to base in space and time
Institution:1. Centre for Earth Evolution and Dynamics (CEED), University of Oslo, 0316 Oslo, Norway;2. Geodynamics, Geological Survey of Norway, 7040 Trondheim, Norway;3. School of Geosciences, University of the Witwatersrand, Johannesburg, South Africa;4. Department of Earth Sciences, The Natural History Museum, Cromwell Road, London SW7 5BD, UK;1. School of Earth & Environmental Sciences, University of Wollongong, New South Wales 2522, Australia;2. School of Earth and Environmental Sciences, James Cook University, Townsville, Queensland 4811, Australia;1. Programa de Pós-graduação em Geologia – PPGL, Universidade Federal do Rio de Janeiro – UFRJ, CEP 21941-916 Rio de Janeiro, Brazil;2. Departamento de Geologia-IGEO, Universidade Federal do Rio de Janeiro – UFRJ, CEP 21941-916 Rio de Janeiro, Brazil;3. Earthworks BV, Achterom 41A, 2611 PL Delft, the Netherlands;1. State Key Laboratory of Geological Processes and Mineral Resources, China University of Geosciences, Wuhan 430074, China;2. School of Earth Sciences, China University of Geosciences, Wuhan 430074, China;3. Earth Sciences, Earth Studies Building C02, School of Environment and Rural Science, University of New England, Armidale, NSW 2351, Australia
Abstract:Gondwana is reviewed from the unification of its several cratons in the Late Neoproterozoic, through its combination with Laurussia in the Carboniferous to form Pangea and up to its progressive fragmentation in the Mesozoic. For much of that time it was the largest continental unit on Earth, covering almost 100 million km2, and its remnants constitute 64% of all land areas today. New palaeogeographical reconstructions are presented, ranging from the Early Cambrian (540 Ma) through to just before the final Pangea breakup at 200 Ma, which show the distributions of land, shallow and deep shelves, oceans, reefs and other features at nine selected Palaeozoic intervals. The South Pole was within Gondwana and the Gondwanan sector of Pangea for nearly all of the Palaeozoic, and thus the deposition of significant glaciogenic rocks in the brief Late Ordovician (Hirnantian) and the much longer Permo-Carboniferous ice ages help in determining where their ice caps lay, and plotting the evaporites in the superterrane area indicates the positions of the subtropics through time. Reefs are also plotted and selected faunal provinces shown, particularly at times such as the Early Devonian (Emsian), when high climatic gradients are reflected in the provincialisation of shallow-marine benthic faunas, such as brachiopods.In Late Palaeozoic and Early Mesozoic times, Gondwana (with Africa at its core) lay over the African large low shear-wave velocity province (LLSVP), one of two major thermochemical piles covering ca. 10% of the core–mantle boundary. The edges of the LLSVPs (Africa and its Pacific antipode) are the plume generation zones (PGZs) and the source regions of kimberlite intrusions and large igneous provinces (LIPs). Our palaeomagnetic reconstructions constrain the configuration of Gondwana and adjacent continents relative to the spin axis, but in order to relate deep mantle processes to surface processes in a palaeomagnetic reference frame, we have also rotated the PGZs to account for true polar wander. In this way, we visualize how the surface distribution of LIPs and kimberlites relate to Gondwana's passage over the PGZs. There are only two LIPs in the Palaeozoic (510 and 289 Ma) that directly affected Gondwanan continental crust, and kimberlites are rare (83 in total). This is because Gondwana was mostly located between the two LLSVPs. The majority of Palaeozoic kimberlites are Cambrian in age and most were derived from the African PGZ. Sixty-six Early Mesozoic kimberlites are also linked to the African LLSVP. All known LIPs (Kalkarindji, Panjal Traps, Central Atlantic Magmatic Province and Karoo) from 510 to 183 Ma (the lifetime of Gondwana) were derived from plumes associated with the African LLSVP, and three of them probably assisted the breakup of Gondwana and Pangea.
Keywords:
本文献已被 ScienceDirect 等数据库收录!
设为首页 | 免责声明 | 关于勤云 | 加入收藏

Copyright©北京勤云科技发展有限公司  京ICP备09084417号