Concentration de sables lourds sur les plages de la baie de Morlaix (Finistère): Exemples de micro-placers d'origine proximale dans une profonde échancrure littorale en voie de déblaiement rapide par la mer

Abstract

SUMMARY Investigations carried out upon heavy minerals (47 samples) concentrated along the beaches of the bay of Morlaix, a large coastal indentation in the Western Channel, have displayed seven different districts. As a general rule, the coastal placers present a proximal origin. The heavy sands come essentially, by marine erosion and sorting, from late continental sediments (arena and periglacial deposits, head). The outer contributions are small, except for the northwestern end of the bay and especially its northeastern part. The proximal origin of an important part of the sands could account for the future of the beaches, at present time altered by anthropic modifications.