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IUGG XXIV General Assembly July 2-13, 2007 Perugia, Italy
(S) - IASPEI - International Association of Seismology and Physics of the Earth's
Interior
JSW001 Oral Presentation 2399
Temporal evolution and migration of volcanism in Northern Martinique
Island (Lesser Antilles, French West Indies)
Mrs. Aurelie Germa
Laboratoire de gochronologie, UMR IDES Universit Paris Sud (PARIS XI) IAVCEI
Quidelleur Xavier, Labanieh Shasa, Chauvel Catherine
Martinique (14N, 61W) is the Lesser Antilles Island where the most complete volcanic history of the arc
can be found. However, most studies have been restricted to Mount Pele volcano, more particularly to
the destructive 1902 and 1929 A.D. eruptions, rather than on the older zones from the recent arc
(Morne Jacob, Pitons du Carbet and Mount Conil complexes), which recorded at least five events of
flank collapse. The aim of this study is to determine the volcanic evolution of the recent arc in
Martinique Island by constraining the building and destructive rates of the different volcanic complexes
in order to improve the knowledge of its recent activity. Dating of nearly thirty selected representative
samples from the northern volcanic complexes has been obtained by K-Ar, based on the Cassignol-Gillot
technique. Together with these radiometric ages, ongoing morphological works and field observations
will help us to better reconstruct the volcanic history of the Morne Jacob, Pitons du Carbet and Mont
Conil complexes, and to characterize their relationship with the active volcano of Mount Pele. First
results show that Morne Jacob volcano has a longer history than previously inferred: the different
stages of activity range between 5.5 and 1.5 Ma. A large basaltic to andesitic shield volcano was built
between 5.5 and 2.1 Ma. At the end of this first stage, the northeastern flank collapsed. A new andesitic
centre erupted into the depression, and peripheric vents emitted lava flows down to the Caribbean
coasts, between 2.04 and 1.5 Ma. Piton du Carbet complex is younger than estimated before: a first
stage of activity occurred with the construction of an andesitic volcano between 1 Ma and 770 ka, which
ended by a large flank collapse southwest directed. The loss of lithostatic load favoured more basic
magma ascent and eruption of Pitons du Carbet s.s. inside the depression. The mean emplacement age
of the Pitons du Carbet being of 337 5 ka (Samper et al., 2007), it is interpreted as the flank collapse
age. Pitons Mont Conil and Mount Pele constitute the northernmost compartment of the island. Piton
Mont Conil complex started its activity while the Carbet complex was still active, with andesites emitted
between 543 8 ka and 189 3 ka. Its evolution and the relationship with the subsequent stages remains
to be better constrained because its activity preceded that of Mount Pele, the active volcano. Finally, our
combined approach based on geochronological, geochemistry, geomorphological and fieldwork studies,
will allow us to propose a general evolution model for the recent arc volcanism in northern Martinique
island, from 5.5 Ma to present.
Keywords: martinique, k argeochronology, flank collapse