Browsing by Author "Alloway, BV"

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    Archaeological implications of a widespread 13th Century tephra marker across the central Indonesian Archipelago
    (Elsevier, 2016-01-01) Alloway, BV; Andreastuti, S; Setiawan, R; Miksic, JN; Hua, Q
    Despite the occurrence of exceptionally large eruptions in the Indonesian Archipelago in recent historic times (i.e. Krakatoa 1883, Tambora 1815), no historic tephra beds have been widely identified in the terrestrial realm that could facilitate the correlation of equivalent aged sequences and/or archaeological remains. This study has identified one such tephra bed of 13th Century age that can be correlated throughout central-east Java and now can be unequivocally correlated with the Samalas 1257 A.D. tephra recently described from Lombok. The occurrence of this historic tephra marker extending ≥650 km west from its eruptive source provides the first opportunity to effect inter-regional correlation over large swathes of central Indonesia. It remains entirely conceivable that in the aftermath of this exceptionally large eruptive event there was considerable westward disruption to subsistence agriculture and trade, food shortages and famine, dislocation of affected populations and socio-political unrest on a scale that equalled or exceeded the catastrophic effects documented from the more recent Tambora 1815 A.D. eruption. Indeed the effects of this mid-13th Century eruption can be registered globally in a variety of records from Antarctica, Europe, Middle East and the Americas. Unfortunately, archaeological evidence indicating such disruption in mid-13th Century Indonesia is yet to be deciphered from the so-far sparse accounts and inscriptions of that time. However, this paucity of evidence does not diminish the utility of this widespread tephra bed as a unique chronostratigraphic marker for archaeological studies across large areas of central Indonesia. © 2016, Elsevier Ltd.
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    Developing an event stratigraphy for Australasian climate change
    (American Geophysical Union, 2011-06-03) Shulmeister, J; Turney, CSM; Fink, D; Newnham, RM; Alloway, BV
    The last glacial-interglacial transition in the Australasian region has been a focus of intense paleoclimate investigation for the past decade or so. This focus is due to the recognition of the southern midlatitudes as a key region to examine climate connections between the hemispheres during the late Pleistocene. That period, between 30,000 and 8000 years ago, was marked by extreme and rapid climatic change in the North Atlantic region. In particular, the Australasian region may be critical to examining the relative importance of atmospheric energy transfers versus deep ocean circulation effects. In February 2006, 32 members of the Australasian Integration of Ice, Marine and Terrestrial records (INTIMATE) program attended a two-day workshop at the University of Auckland, in New Zealand. ©2006. American Geophysical Union.
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    Exploring the source-to-sink residence time of terrestrial pollen deposited offshore Westland, New Zealand
    (Elsevier, 2016-07-01) Ryan, MT; Newnham, RM; Dunbar, GB; Vandergoes, MJ; Rees, ABH; Neil, H; Callard, SL; Alloway, BV; Bostock, HC; Hua, Q; Anderson, BM
    The occurrence of terrestrial palynomorphs in Quaternary marine sedimentary sequences allows for direct land–sea correlations and provides a means for transferring Marine Isotope Stage chronologies to terrestrial records that extend beyond the range of radiocarbon dating. Both of these important applications require an implicit assumption that the lag between pollen release and final deposition on the seafloor – here referred to as source-to-sink residence time – is negligible in relation to the chronological resolution of the sedimentary sequence. Most studies implicitly assume zero lag, and where studies do take palynomorph residence time into account, its magnitude is rarely quantified. In Westland, New Zealand, fluvial transport is the main source of delivery of terrestrial pollen offshore to the adjacent East Tasman Sea. We radiocarbon-dated organic matter carried and deposited by contemporary Westland rivers that drain catchments with varying degrees of disturbance. The ages obtained ranged widely from essentially modern (i.e., − 57 ± 22 cal yr BP) to 3583 ± 188 cal yr BP, suggesting that precisely constraining the residence time in this region is unlikely to be achieved. We also compared the timing of four palynomorph events characterising Westland's late Pleistocene, along with the well-dated Kawakawa/Oruanui Tephra (KOT), between marine core MD06-2991 and four terrestrial records from Westland. Critically, all palynomorph events and the KOT are chronologically indistinguishable with respect to the independently dated marine and terrestrial records, supporting the general principle of transferring the marine chronology onto the terrestrial records in this setting. In other regions, particularly those lacking the high soil production and erosion rates that characterise Westland, we suggest that similar tests of marine residence time should be conducted before assumptions of zero or negligible lag are invoked.© 2016, Elsevier B.V.