First insights into mid-Holocene environmental change in central Vanuatu inferred from a terrestrial record from Emaotfer Swamp, Efaté Island

Denis Wirrmann (1) , Stephen H. Eagar , Margaret A. Harper , Éric Leroy , Anne-Marie Sémah (1)

1 LOCEAN - Laboratoire d'Océanographie et du Climat : Expérimentations et Approches Numériques

Here we present the first terrestrial record of mid-Holocene environmental changes in Vanuatu. This preliminary multi-proxy analysis of core Tfer 06 from Emaotfer Swamp (Efaté Island) indicates changes in environmental conditions are mainly related to variations in climate over the last 6500 cal yr BP. Drier periods are broadly correlated with an increase in sustained El Niño events recorded in the Pacific on a decadal timescale. The earliest change is the disappearance of mangroves adjacent to the site around 3200 cal yr BP, this could well be due to both local tectonic uplift with subsequent hydrostatic adjustment and the onset of a drier period. From c. 3250-2500 cal yr BP the prevailing drier conditions can be linked to more persistent El Niño conditions. Local volcanic events had limited ecological impact on the area. Freshwater diatoms indicate a hydroseral succession, species living on submerged plants being common in muds from c. 3250-1500 cal yr BP, but rare in fibrous peat deposited later. Palaeoecological indicators of human impact have not been identified throughout this work.

Domaines: Géophysique [physics.geo-ph]; Géophysique [physics.geo-ph]

Denis Wirrmann, Stephen H. Eagar, Margaret A. Harper, Éric Leroy, Anne-Marie Sémah. First insights into mid-Holocene environmental change in central Vanuatu inferred from a terrestrial record from Emaotfer Swamp, Efaté Island. Quaternary Science Reviews, 2011, 30, pp.3908-3924. ⟨10.1016/J.QUASCIREV.2011.10.003⟩. ⟨hal-00755895⟩