Raised marine sequences of Lanzarote and Fuerteventuraudrevisited —a reappraisal of relative sea- level changes and verticaludmovements in the eastern Canary Islands during the Quaternary

摘要

Systematic mapping and morphosedimentary analysis of Fuerteventura and Lanzarote Islands supported by laboratoryudtechniques (U-series mostly by TIMS, 14C analysis and allo-isoleucine measurements on biogenic carbonates from raised marineuddeposits, paleomagnetic and a few K/Ar measurements on volcanic formations related to marine deposits) provide a basis forudconstraining the age of Late Cainozoic marine units. The most complete sequences of raised marine terraces are found at similarudelevations in both islands. They include up to 12 marine terraces (Episodes) at elevations between 0m and 70m above mean sea levelud(asl). At least six terraces should be of Quaternary age, and more recent than 1.2 Myr. Throughout the whole marine sequence withudthe exception of the Holocene terrace, the warm fauna assemblage is characterized by the presence of Ostrea virleti, Nerita emiliana,udand Strombus (S. cf. coronatus–S. cf. bubonius). However, there is a major change, highlighted by the disappearance of the first twoudspecies, below the 8–10m terrace, that could possibly correspond to MIS 11. K–Ar measurements allow an estimate for mean upliftudrate of 1.7 cm/ka during the last million years. The present elevation of the Last Interglacial deposits (about 1 and 2masl) showsuddiscontinuous vertical movements with possibly a reverse trend since MIS 9 in eastern Canary Islands