FAST HOLOCENE UPLIFT RATES AT THE ANDES OF CHILOE, SOUTHERN CHILE

Seven C-14 ages on shell material from elevated beaches in the Andes o f Chiloe (42-43-degrees-S) indicate ages varying from 420+/-80 to 3,13 0+/-80 yr B.P. Estimated elevations of the sampled localities show tha t uplift of the order of 10 m/ka has affected the region. In this segm ent of the Andes, where amounts of coseismic uplift/subsidence of the order of 1 m were observed during the 1960 earthquake, the east-west d istribution of the measured uplift rates is probably related to late H olocene coseismic deformation. Uncertainties concerning the contributi on of postglacial isostatic rebound on paleo sea level and on the wate r depth at which the dated shells lived do not invalidate this conclus ion. Uplift is probably related to the Liquine-Ofqui Fault Zone which crosses the area.