Abstract

BORROMEI, Ana M.  and  QUATTROCCHIO, Mirta. Holocene sea-level change inferred from palynological data in the Beagle Channel, southern Tierra del Fuego, Argentina. Ameghiniana [online]. 2007, vol.44, n.1, pp.161-171. ISSN 1851-8044.

An early-middle Holocene section in Bahía Lapataia (54º 50' S, 68º 34' W), Beagle Channel, Tierra del Fuego, Argentina has been examined taking into account its sporomorphs and organic-walled microplankton. The palynological assemblage suggests nearshore environments. Two relatively higher sea levels were identified by the increased abundance of organic-walled dinoflagellate cysts (Brigantedinium spp., Selenopemphix sp., Operculodinium centrocarpum sensu Wall and Dale, Spiniferites spp.), the acritarch Halodinium sp. and zoomorph remains (test linings of foraminifera and copepod egg-envelopes). The littoral vegetation at the time of the marine incursion was mainly arboreal, as can be seen in the pollen records by significant increase in Nothofagus dombeyi type frequencies, while a forest-steppe vegetational pattern developed regionally. After comparison with another nearby fossil marine terrace, the palynological analysis has demonstrated that these terraces represent the same transgressive-regressive event. The relative altitudinal differences between these terraces in the area may be the result of seismotectonic activity during the Holocene.

Keywords : Palynology; Paleoenvironment; Holocene transgression; Bahía Lapataia; Beagle Channel; Tierra del Fuego; Argentina.