Late-glacial and Holocene palaeoenvironmental change in the central Straitof Magellan, southern Patagonia

I-Ii.-h-resolution palaeoenvironmental data for the Wisconsin Late-glacial and early Holocene is provided from two sites, Puerto del Hambre and Estanc ia Esmeralda II, in the central section of the Strait of Magellan, southern Chile, Palaeoecological and lithostratigraphical evidence is correlated wi th other palaeoenvironmental data from the Magellan region using C-14 datin g and tephrochronology. The oldest record, from Puerto del Hambre, commence s at 14,470 C-14 yr BP (17,330 cal. yr BP), following retreat of the Magell an glacier. Climatic warming, after that time is indicated by ice retreat f rom the central section of the Strait of Magellan and palynological evidenc e. However, mean annual temperature continued to be cooler than present unt il c. 10,300 C-14 yr BP (12,270-12,110 cal. yr BP). The Magellan environmen t was relatively humid between c. 14,100 and c. 12,550 C-14 yr BP (16,910 a nd 15,170-14,410 cal. yr Bp). At c. 12,550 C-14 yr BP, there was a sharp de crease in effective moisture. Levels of humidity fluctuated, but remained r elatively low until c. 10,300 C-14 yr Bp. This period of cool and drier cli mate is contemporary with a significant glacier advance dated to between c, 12,700 and 10,300 C-14 yr BP (15,330 and 12,270-12,110 cal. yr BP), which would have produced an enhanced rainshadow effect. Around 10,300 C-14 yr BP a shift to warmer conditions occurred. Between c. 10,300 and 8550 C-14 yr BP (12,270-12,110 and 9530 cal. yr Bp) an extreme and phase is recorded, wh ich led to an increase in fixes. At c. 8550 C-14 yr BP an increase in avail able moisture allowed the eastward spread of Nothofagus forest. At 8265 C-1 4 yr BP (9270-9160 cal. yr BP) there was a relative rise in sea level in th e Strait of Magellan. This marine incursion lasted until 3970 C-14 yr BP (4 420 cal. yr BP), reaching its maximum around c. 6450 C-14 yr BP (7420-7340 cal. yr BP). (C) 2001 Elsevier Science B.V. All rights reserved.