Palaeomagnetism and Palaeozoic palaeogeography of Gondwana and European terranes
Palaeomagnetism and Palaeozoic palaeogeography of Gondwana and European terranes
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冈瓦纳古大陆和欧洲地体的古地磁学和古生代古地理
DOI：
10.1144/gsl.sp.2000.179.01.04
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发表时间：
2000
期刊：
影响因子：
--
通讯作者：
H. Soffel
中科院分区：
文献类型：
--
作者：
J. Tait;M. Schätz;V. Bachtadse;H. Soffel
摘要新元古代至晚古生代，Rodinia超大陆解体，泛大陆形成。在此期间，大陆和大陆碎片发生了重大的重新分布，人们提出了这一时期的各种古地理模型。这些模型之间的主要区别在于冈瓦纳大陆的漂移历史、北方非洲与劳鲁西亚碰撞的时间以及泛大陆的形成。古地磁证据提供了两种截然不同的模式，奥陶纪至晚泥盆世的冈瓦纳视极移（APW）路径，涉及该大陆的快速向北和向南运动，或在整个古生代逐渐向北漂移。相比之下，古生物地理模型表明，早在泥盆纪中期，劳鲁西亚和冈瓦纳大陆就已经接触，直到中生代泛古陆解体，大陆基本上仍保持这种结构。然而，这与大多数古地磁数据相冲突，这些数据表明，在泥盆纪晚期，北非和欧洲大陆边缘的劳鲁西亚被至少3000公里宽的海洋分开。这也与现今欧洲南部的地质记录相一致，后者反对北方非洲在泥盆纪时期与欧洲发生任何碰撞。然而，关于劳鲁西亚的形成，古生物地理学和古地磁学数据非常一致，即到泥盆纪中期，分隔波罗的海、劳伦大陆、冈瓦纳衍生的阿瓦隆尼亚和阿摩利肯地体组合（ATA）的海洋盆地已经全部闭合。古地磁和地质数据也一致认为，欧洲阿尔卑斯地区的古生代基底岩石形成了一个独立的微板块，位于劳鲁西亚南部。在晚志留世时期，它被一个C的海洋分开。1000公里，到晚泥盆纪时已接近南普鲁士边缘。根据古地磁资料，冈瓦纳北方边缘在晚泥盆世时仍在更靠南的位置，而根据南欧的地质记录，北方非洲与欧洲的劳鲁西亚的主要陆-陆碰撞和介于其间的洋的闭合发生在晚石炭纪。该缝合线的位置位于古生代阿尔卑斯山单元（如灰砂岩带、卡尼克阿尔卑斯山、撒丁岛和西西里）的南部，但被较年轻的变形事件所掩盖，无法精确定位。评估现有的证据，并在文中讨论，它建议，最有可能的情况是冈瓦纳北方边缘逐渐向北漂移，从奥陶纪到晚石炭世的时候，它与劳鲁西亚碰撞，形成泛大陆。
Abstract Neoproterozoic to Late Palaeozoic times saw the break-up of the supercontinent Rodinia, and the subsequent construction of Pangaea. The intervening time period involved major redistribution of continents and continental fragments, and various palaeogeographical models have been proposed for this period. The principal differences between these models are with regard to the drift history of Gondwana, the timing of collision between northern Africa and Laurussia, and formation of Pangaea. Palaeomagnetic evidence provides basically two contrasting models for the Ordovician to Late Devonian apparent polar wander (APW) path for Gondwana involving either rapid north and southward movement of this continent, or gradual northward drift throughout Palaeozoic time. In contrast, palaeobiogeographical models suggest contact between Laurussia and Gondwana as early as mid-Devonian time with the continents basically remaining in this configuration until break-up of Pangaea in the Mesozoic era. This is in conflict, however, with most palaeomagnetic data, which demonstrate that in Late Devonian time, north Africa and the European margin of Laurussia were separated by an ocean of at least 3000 km width. This is also in agreement with the geological record of present-day southern Europe, which argues against any collision of northern Africa with Europe in Devonian time. With regard to formation of Laurussia, however, palaeobiogeographical and palaeomagnetic data are in excellent agreement that by mid-Devonian time the oceanic basins separating Baltica, Laurentia, Gondwana-derived Avalonia and the Armorican Terrane Assemblage (ATA) had all closed. Palaeomagnetic and geological data are also in agreement that the Palaeozoic basement rocks of the European Alpine realm formed an independent microplate, which was situated to the south of Laurussia. In Late Silurian times it was separated by an ocean of c. 1000 km, and by Late Devonian time was approaching the southern Laurussian margin. According to palaeomagnetic data, the northern margin of Gondwana was still further to the south in Late Devonian time, and according to the geological record in southern Europe, the main continent-continent collision of northern Africa with European Laurussia and closure of the intervening ocean occurred in Late Carboniferous times. Location of this suture is situated to the south of the Palaeozoic alpine units (e.g. the Greywacke zone, Carnic Alps, Sardinia and Sicily), but has been obscured by younger deformational events and cannot be precisely positioned. Assessing available evidence and as discussed in the text, it is proposed that the most likely scenario is that the northern margin of Gondwana drifted gradually northwards from Ordovician to Late Carboniferous times when it collided with Laurussia, resulting in formation of Pangaea.