Heavy-mineral concentrations as proxies of high-energy events along sandy coasts
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Дата
2006
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Astroprint
Анотація
Sediment-rich coastal sequences have the potential of preserving long-term records of regional-scale erosional events. Among the most diagnostic features of erosion are steep berm and dune scarps, regional
unconformities (discontinuities), layers of coarse sediment or shell hash, as well as extensive
accumulations of heavy minerals (magnetite, ilmenite, garnet, zircon, hornblende, etc.). These heavy
mineral concentrations (HMCs) are found in many parts of the world and occur in thin layers or thick placer
deposits (Fig. 1A). Their formation is due primarily to selective density sorting during the waning stages of
storms (Komar and Wang, 1984; Peterson et al., 1986; Kurian et al., 2001). The HMCs can therefore be
used as proxies for high-energy events along sandy coastal regions, and have been attributed to storm or tsunami-induced erosion in a number of studies (Smith and Jackson, 1990; Nichol, 2002; Buynevich et al., 2004; Dougherty et al., 2004). Substantial contrast in electromagnetic properties between sands enriched
in ferromagnesian heavy minerals and quartz-rich background sediments is responsible for the sharp
nature of subsurface reflections (Meyers et al., 1996; Buynevich et al., 2004) making HMCs some of the
most prominent horizons in ground-penetrating radar (GPR) profiles (Fig. 1B). By combining
high-resolution geophysics for mapping subsurface erosional indicators with radiocarbon or optical dating of individual erosional horizons, it is possible to reconstruct the long-term history of coastal hazards in various parts of the world.
Опис
Збірка тез доповідей 2-ї конференції та польових екскурсій за Проектом IGCP-521» Чорноморсько-Середземноморський Коридор упродовж останніх 30 тис.років: зміни рівня моря та адаптація людини» (2005-2006). Одеса,20-28 серпня,2006 р. Одеса: Астрапринт,2006
Ключові слова
storm, tsunami, GPR, scarp, lag
Бібліографічний опис
Black sea – mediterranean corridor during the last 30 ky: sea level change and human adaptation (2005–2009) : ІІ plenary meeting and field trip of project IGCP-521 (Odessa, 20–28 August 2006). – Odessa : Astroprint, 2006.