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Browsing Book Chapters by Subject "Age estimation"

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    14.30 An introduction to dating techniques: a guide for geomorphologists
    (Elsevier, 2013-01-01) Sloss, CR; Westaway, KE; Hua, Q; Murray-Wallace, CV
    This chapter provides researchers with a guide to some of the types of dating techniques that can be used in geo- morphological investigations and issues that need to be addressed when using geochronological data, specifically issues relating to accuracy and precision. This chapter also introduces the ‘types’ of dating methods that are commonly used in geomorphological studies. This includes sidereal, isotopic, radiogenic, and chemical dating methods. © 2013 Elsevier Inc.
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    Climate change and groundwater
    (Springer, 2011-09-23) Hughes, CE; Cendón, DI; Johansen, MP; Meredith, KT
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    Examining late holocene marine reservoir effect in archaeological fauna at Hope Inlet, Beagle Gulf, North Australia.
    (The Australian National University (ANU), 2009-02) Bourke, P; Hua, Q
    This study examines the marine reservoir effect during the Late Holocene evolution of a small estuary in the Beagle Gulf (12°S, 131°E). The paper aims at refining the local marine reservoir ages (R) and correction values (ΔR), by 14C analysis of stratigraphically associated archaeological fauna (marine shell, charcoal and fish otoliths) from five proximate middens of different chronologies. The results suggest that a marine reservoir age of 340 ± 70 yrs is applicable to the Beagle Gulf for the Late Holocene, which is not significantly different from that determined for nearby Van Dieman Gulf and the north Australian coast. © 2009, The Australian National University (ANU)
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    History of Australian aridity: chronology in the evolution of arid landscapes
    (Geological Society of London, 2010-01-01) Fujioka, T; Chappell, J
    Australian climate and vegetation, known from marine and lacustrine sediments and fossils, varied dramatically throughout the Cenozoic Era, with several warm reversals superimposed on overall drying and cooling. A suite of landforms, including stony deserts, dunefields and playa lakes, formed in response to the advancing aridity but their age generally remained uncertain until fairly recently, owing to a lack of suitable dating methods. Within the last 5 years, the chronology of Late Quaternary fluctuations of lakes, dunes and dust-mantles has been established by luminescence dating methods, and mid-Pleistocene onset of playa conditions in a few closed basins has been estimated using palaeomagnetic reversal chronology. Only recently has it been shown, by cosmogenic isotope dating, that major tracts of arid landforms including the Simpson Desert dunefield, and stony deserts of the Lake Eyre Basin, were formed in early Pleistocene and late Pliocene times, respectively. These landscapes represent a stepwise response to progressive climatic drying and, speculatively, were accompanied by biological adaptations. Recent molecular DNA studies indicate that Australia's arid-adapted species evolved from mesic-adapted ancestors during the Pliocene or earlier, but whether speciation rapidly accompanied the development of stony deserts and other arid geomorphological provinces awaits further studies of arid landscape chronology. © The Geological Society of London 2010
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    Late Pleistocene glaciers and climate in the High Atlas, North Africa
    (GeoScienceWorld, 2020-04-07) Hughes, PD; Fink, D; Fletcher, WJ
    Extensive glaciers covered the High Atlas mountains in Morocco during the late Pleistocene. On the northern escarpments of the Marrakech High Atlas, a series of cirques perched at ~3000–3500 m above sea level (asl) fed their valley glaciers that, in some cases, extended to as low as 2000 m asl. Cosmogenic exposure dating with 10Be and 36Cl has shown that at least three phases of glaciation are preserved in glacial deposits over the last glacial cycle at 50, 22, and 12 ka, which appear to correlate with marine isotope stage (MIS) 3, the global Last Glacial Maximum (LGM), and the Younger Dryas chronozone. This geochronological framework is sufficiently robust to allow for time-constrained glacier-climate reconstructions. The glaciers associated with these three phases of advance had equilibrium line altitudes (ELAs) of 2761 m asl (ca. 50 ka), 2919 m asl (ca. 22 ka), and 3213 m asl (ca. 12 ka). Glacier-climate modeling suggests that all of these phases were driven by both colder temperatures and wetter conditions than today. The dominant moisture supply to these glaciers in all phases would have been sourced from Atlantic depressions. The influence of an extended and enhanced West African monsoon on glacier development during African Humid Periods is unlikely to have been a significant influence on glacier dynamics. The climate conditions associated with the three glacier phases indicate sustained moisture supply to the highest mountain areas when records from other areas, such as the Middle Atlas lakes and marine sediment cores offshore, indicate marked aridity. © 2020 The Geological Society of America