1.1. HISTORICAL DEVELOPMENT OF THE OPHIOLITE CONCEPT. Ophiolite, Greek
for 'the snake stone', appears to have received its first written
definition by Brongniart (1813) as a serpentine matrix containing
various minerals. Later in 1821 and 1827, Brongniart determined that
volcanic and gabbroic rocks were also present, associated with cherts,
and he ascribed an igneous origin to the ophiolite. Amstutz (1980) gives
an excellent exegesis of these early contributions and traces the
further use of the term and concept of ophiolite. This concept had been
forged in the western Alps and Apennines where, thanks to talented
Italian geologists, in particular A. Sismonda, B. Gastaldi, V. Novarese
and S. Franchi, the study on metamorphic ophiolites (the 'pietre verdi')
has rapidly progressed. At the tum of the century the association of
radiolarite, diabase, gabbro (euphotide), and serpentinite-peridotite
was clearly identified, even through their metamorphic transformations.
In 1902, Franchi developed the hypothesis introduced earlier by Lotti
(1886), of a submarine outflow to explain the 'pietre verdi'
association, on the basis of the attribution of the variolites and
metamorphic prasinites to an hypabyssal volcanism, also responsible for
the formation of radiolarites. Thus, before the popular work of
Steinmann in 1927, the various components constituting an ophiolite had
been identified and its hypabyssal origin proposed. As recalled by
Amstutz (1980), the so-called 'Steinmann trinity', which consists of the
association of radiolarites, diabases and serpentinites, was more
completely and better defined in these earlier works.