"As summarized by Andriamirado (1971) and McElhinny etal. (1976). Symbols are as in Table 6.5.

"As summarized by Andriamirado (1971) and McElhinny etal. (1976). Symbols are as in Table 6.5.

to Early Cretaceous (near 55N). During the Late Cretaceous its position returns to near 70N.

The data from Madagascar are listed in Table 6.12 with the corresponding APWP illustrated in Fig. 6.20b. The Late Cretaceous results from volcanics along the east coast are due to Andriamirado (1971) and the remaining data are those summarized by McElhinny et al. (1976). At the time of writing no new data had been reported for more than twenty years. Only 12 pole positions representing 83 sites have been determined for Madagascar.

The major cratons of South America are the Amazonia and Rio de la Plata cratons (Fig. 6.19b). The Sao Francisco craton to the east was formerly a western extension of the Congo craton of Africa. In the northeast there is a small remnant of the West Africa craton shown in Fig. 6.19a. The western margin of South America contains displaced terranes of various ages, the most important of which (in the context of this book) is the Arequipa Massif. This is thought to be a former part of Laurentia (North Britain terrane) that became detached when it collided with the western margin of South America near the Precambrian-Cambrian boundary (Dalziel, 1997; see ยง7.4.3).

The first paleomagnetic measurements in South America were reported by Creer (1958), and his later studies and those of his students and associates are summarized in Creer (1970). Workers in Argentina and Brazil set up their own laboratories and a later summary is given by Vilas (1981). Much work has been carried out in Chile and along the western margin of South America. Most of this work relates to various displaced terranes and is not therefore considered in the context of constructing an APWP for South America. Currently, there are 65 acceptable results derived from 1061 sites as listed in Table 6.13.

Most of these results are concentrated in the time interval Late Carboniferous to Late Cretaceous. The large number of sites for the Early Cretaceous come from the many studies that have been carried out on the Serra Geral Formation in Brazil and Uruguay. There appear to have been some difficulties in obtaining good data for pre-Late Carboniferous times. Furthermore, especially for the Ordovician and Cambrian, ages are only known within the broad limits of the

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