Paleogeographic reconstructions based on paleomagnetism

Reconstructions of the relative positions of the main continental areas at various times in the past 200 Ma are best achieved using the very detailed information on the evolution of the present ocean basins provided by the linear oceanic magnetic anomalies

Figure 3.14 Apparent polar wander paths for North America (solid circles and solid line) and Europe (open circles and dashed line) (a) with North America and Europe in their present positions, and (b) after closing the Atlantic ocean. Ages for each mean pole position are given in Ma with those for Europe in italics (redrawn from McElhinny & McFadden, 2000, with permission from Academic Press. Copyright Elsevier 2000).

Figure 3.14 Apparent polar wander paths for North America (solid circles and solid line) and Europe (open circles and dashed line) (a) with North America and Europe in their present positions, and (b) after closing the Atlantic ocean. Ages for each mean pole position are given in Ma with those for Europe in italics (redrawn from McElhinny & McFadden, 2000, with permission from Academic Press. Copyright Elsevier 2000).

A Ocean closure v and suturing of continents

Rifting and % recreation of ocean % _

Figure 3.15 Paleomagnetic signature of plate divergence and convergence (redrawn from Irving et al., 1974, by permission of the American Geophysical Union. Copyright © 1974 American Geoplysical Union).

Figure 3.16 APW path for Gondwana, based on the reconstruction of Lottes & Rowley (1990) (redrawn from Torsvik & Van der Voo, 2002, with permission from Blackwell Publishing).

(Section 4.1.7). In order to position the continents in their correct paleolatitudes however, paleomagnetic results must be combined with these reconstructions to identify the positions of the paleopoles and paleo-equator. The sequence of paleogeographic maps in Chapter 13 (Figs 13.2-13.7) was obtained in this way. For any time prior to 200 Ma the constraints provided by the oceanic data are no longer available and reconstructions are based on paleomagnetic results and geologic correlations. Examples of these pre-Mesozoic reconstructions will be discussed in Chapter 11.

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