Earth at 200 Ma: Global palaeogeography refined from CAMP palaeomagnetic data

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• 作者：Vicente Carlos Ruiz-Martí ; nez^a ; ^b ; ^{vcarlos@fis.ucm.es} ; Trond H. Torsvik^b ; ^c ; ^d ; ^e ; Douwe J.J. van Hinsbergen^b ; ^c ; Carmen Gaina^b ; ^c
• 关键词：palaeomagnetism ; palaeogeography ; Pangea breakup ; mantle plumes ; CAMP ; Morocco
• 刊名：Earth and Planetary Science Letters
• 出版年：2012
• 期刊代码：18_0012821x
• 类别：ph
• 出版时间：15 May, 2012
• 卷：331-332
• 期：Complete
• 页码：67-79
• 文件大小：5561 K

摘要

The Central Atlantic Magmatic Province was formed approximately 200 Ma ago as a prelude to the breakup of Pangea, and may have been a cause of the Triassic-Jurassic mass extinction. Based on a combination of (i) a new palaeomagnetic pole from the CAMP related Argana lavas (Moroccan Meseta Block), (ii) a global compilation of 190-210 Ma poles, and (iii) a re-evaluation of relative fits between NW Africa, the Moroccan Meseta Block and Iberia, we calculate a new global 200 Ma pole (latitude = 70.1掳 S, longitude = 56.7掳 E and Ab>95b> = 2.7掳; N = 40 poles; NW Africa co-ordinates). We consider the palaeomagnetic database to be robust at 200 卤 10 Ma, which allows us to craft precise reconstructions near the Triassic-Jurassic boundary: at this very important time in Earth history, Pangea was near-equatorially centered, the western sector was dominated by plate convergence and subduction, while in the eastern sector, the Palaeotethys oceanic domain was almost consumed because of a widening Neothethys. We show that there has been negligible net displacement of the Moroccan Meseta relative to Africa since 200 Ma. We calculate a new fit between Iberia and NW Africa, showing that models inferring minor Cretaceous rotation and major Cretaceous sinistral translation of Iberia relative to Europe are inconsistent with palaeomagnetic Iberia-Africa fits at 200 Ma. During Pangea breakup (~ 195 Ma, opening of the Central Atlantic), and shortly after the CAMP outburst, Laurasia rotated clockwise relative to Gondwana around an Euler pole located in SE Iberia. The CAMP and its likely contribution to climate change, mass extinction and Pangea breakup profoundly changed planet Earth and we show that CAMP was sourced by a deep mantle plume that started its disturbing journey from the core-mantle boundary.