DIAPIRISM AND INTRAPLATE EXTENSION - CAUS E OR CONSEQUENCE

The mechanisms leading to the initiation of intraplate rifting are sti ll poorly constrained. A mechanism of intraplate extensional stresses and strain concentration is proposed. Large intrusions in the upper cr ust would favor rift-zone development in the trend of the maximum prin cipal horizontal stress, in a way similar to hydraulic fracturing arou nd drilling cores under pressure. Two possible examples of such mechan ism at regional scale are described, both in intraplate continental an d intraplate oceanic domains. (C) Academie des sciences/Elsevier, Pari s.