Late Holocene paleoenvironment in northern New Caledonia, southwestern Pacific, from a multiproxy analysis of lake sediments

摘要

Lithostratigraphic and palynological analysis of two cores recovered from the 'Grand Lac' (New Caledonia), combined with 35 C-14 AMS dates, yields a paleoenvironmental record spanning the last 2000 yr. The lithology is represented mainly by clayey or laminated layers. A catastrophic event, which is marked by very coarse deposits, occurred probably between ea 1070-960 cal yr B.P. and possibly is associated with an unusually severe La Nina event. Before and after this event, a similar combination of the two main sediment types is recorded. The repeated alternation of laminated and clayey layers is interpreted as the response to local hydrologic forcing, which may reflect a shift from relatively wet to relatively drier conditions, respectively. Variable amount of micro-charcoal is detected all along the profile. Without additional evidence, notwithstanding the initial local human settlement documented since ca 2900 C-14 yr B.P., micro-charcoal occurrence and variability cannot be linked directly to an anthropogenic origin. No distinct palynological zonations in relation to the lithology are observed, and the vegetation changes may only represent minor transitions across environmental limits. (c) 2006 University of Washington. All rights reserved.