A late holocene record of environmental changes from coastal wetlands:: Abel Tasman National Park, New Zealand

Particle size, organic content, loss on ignition (LOI), geochemistry, radiocarbon and Cs-137 analyses were carried out on paired cores taken from Wainui, Totaranui and Awaroa Inlets, Abel Tasman National Park. A 1700 year record of long- and short-term environmental changes was produced representing a sedimentary and geochemical sequence from tidal Bat to mature salt marsh. The sequence is punctuated by a series of short-term environmental changes, namely tsunami, establishment of salt marsh, and European settlement. Long-term environmental changes include fluctuating accretion rates and relative sea level rise. Tsunami "signatures" include: (i) a peak in fines, (ii) contemporaneous or "delayed" peak in organic content and/or LOI, (iii) contemporaneous peaks in Fe and/or S, (iv) dilution of anthropogenic contaminants, and (v) visible change in the sediments. Ruptures of the Wellington and West Wairarapa Faults are considered to be the tsunamigenic sources. Pre-European sediment accretion rates in Abel Tasman National Park range from 0.5 to 1.7 mm/a, with post-European settlement rates increasing to 1.6-2.7 mm/a. In the past 30 years, rates have increased to 2.3-3.3 mm/a. The component of relative sea level rise is estimated to be about 1.3-2.2 mm/a which compares favourably with the nearest tidal records from Wellington. (C) 1999 INQUA/Elsevier Science Ltd. All rights reserved.