Browsing Radiocarbon, Volume 46, Number 2 (2004) by Authors
Oceanic Radiocarbon and Tritium on a Transect between Australia and Bali (Eastern Indian Ocean)Leboucher, Viviane; Jean-Baptiste, Philippe; Fourré, Elise; Arnold, Maurice; Fieux, Michèle (Department of Geosciences, The University of Arizona, 2004-01-01)Results are presented of radiocarbon and tritium measurements along a transect between the Australian continental shelf and the Indonesian coast of Bali. The stations lie in the easternmost part of the Indian Ocean, close to the sills over which the Indonesian throughflow (ITF) makes its way to the Indian Ocean. The present data, obtained as part of the Java-Australia Dynamics Experiment (JADE) in August 1989, complement the WOCE 14C and tritium data set on both sides of the Indonesian archipelago and give us the opportunity to discuss the origin of the water masses and timescale of the throughflow. Both tracers point to a north equatorial Pacific origin of the waters. The comparison of the tritium inventories in the Pacific North Equatorial Current and along the JADE transect suggests a minimum transit time of the waters across the Indonesian seaways of the order of 5 to 6 yr, corresponding to a throughflow smaller than <18 x 10^6 m3/s.
Paired 14C and 230Th/U Dating of Surface Corals from the Marquesas and Vanuatu (Sub-Equatorial Pacific) in the 3000 to 15,000 Cal Yr IntervalPaterne, Martine; Ayliffe, Linda K.; Arnold, Maurice; Cabioch, Guy; Tisnérat-Laborde, Nadine; Edouar, Edouard Bard; Douville, Eric; Bard, Edouard (Department of Geosciences, The University of Arizona, 2004-01-01)Paired radiocarbon and 230Th/U dating was performed on 13 surface corals from submerged reefs in the Marquesas and from raised terraces in Vanuatu. The absolute ages of the corals analyzed ranged from 3000 to 15,000 cal yr. Estimates of the difference between the absolute and 14C ages of these corals are in agreement with previous determinations up until 11,500 cal yr. The resulting mean sea surface reservoir age R is determined at 390 +/60 yr for the Marquesas region (9 degrees S), which is slightly higher than the R value at 280 +/50 yr for the Tahiti Islands (18 degrees S). Multiple 14C analyses of 2 corals from the Marquesas present scattered 14C ages at ~12,000 and ~15,100 cal yr. This could be attributed to rapid changes of the 14C content of surface waters around the Marquesas Islands or to a subtle submarine diagenesis.