a mid-凯发官网入口

a mid-holocene candidate tsunami deposit from the nw cape(western australia)simon matthias maya, ⁎ , simon falvard b , maike norpoth a , anna pint a , dominik brill a , max engel a ,anja scheffersc , manuel dierick d , raphaël paris b , peter squire c , helmut brückner aainstitute of geography, university of cologne, albertus-magnus-platz, 50923 cologne, germanyblaboratoire magmas et volcans, université blaise pascal, cnrs–ird, opgc, 5 rue kessler, 63038 clermont-ferrand, francecsouthern cross geoscience, southern cross university, po box 157, lismore, nsw 2480, australiaddepartment of physics and astronomy, centre for x-ray tomography, ghent university, proeftuinstraat 86, 9000 ghent, belgiuma b s t r a c t a r t i c l e i n f oarticle history:received 15 october 2015received in revised form 19 november 2015accepted 20 november 2015available online 23 november 2015editor: dr. j. knightalthough extreme-wave events are frequent along the northwestern coast of western australia and tsunamis in1994 and 2006 induced considerable coastal flooding locally, robust stratigraphical evidence of prehistoric trop-ical cyclones and tsunamis from this area is lacking. based on the analyses of x-ray computed microtomography(μct) of oriented sediment cores, multi-proxy sediment and microfaunal analyses, optically stimulated lumines-cence (osl) and14 c-ams dating, this study presents detailed investigations on an allochthonous sand layer ofmarine origin found in a back-barrier depression on the nw cape range peninsula. the event layer consists ofmaterial from the adjacent beach and dune, fines and thins inland, and was traced up to ~400 m onshore.although a cyclone-induced origin cannot entirely be ruled out, the particular architecture and fabric of thesediment, rip-up clasts and three subunits point to deposition by a tsunami. as such, it represents the firststratigraphical evidence of a prehistoric, mid-holocene tsunami in nw western australia. it was osl-dated to5400–4300 years ago, thus postdating the regional mid-holocene sea-level highstand.© 2015 elsevier b.v. all rights reserved.keywords:palaeotsunami depositsediment fabricx-ray microtomographyoptically stimulated luminescence1. introductionthe nw coast of western australia is impacted by 1–2 tropicalcyclones per year, and ten tsunamis have been recorded since 1858,including those following the 1883 krakatoa eruption and the earth-quakes off the coast of indonesia in 1977, 1994 and 2006 (goff andchagué-goff, 2014). although observations during these tsunamis arerather sporadic, wave heights of ~6 m (cape leveque) and a run-up of~8 m australian height datum (ahd) (shelter bay, shark bay) locallyoccurred during the 1977 sumba and 2006 java tsunamis, respectively(prendergast and brown, 2012; goff and chagué-goff, 2014). at thenorth west cape, the 1994 java tsunami overwashed the dune barrierat baudin (fig. 1), 3.6 km s of the study area. inundation extended upto 300 m inland, and a run-up of ~7 m ahd was inferred (gregsonand van reeken, 1998). in addition, tropical cyclones cause extensivecoastal flooding. as one of the most powerful cyclones in australia'shistorical record, category 5 tropical cylone vance (march 18th–22nd,1999) resulted in water levels of ~7 m above event tide in the exmouthgulf (nott and hubbert, 2005). however, little is known about thegeological imprint of historical (prendergast and brown, 2012; mayet al., 2015a) and prehistorical extreme-wave events in northwesternwestern australia. so far, prehistorical tsunamis or storms wereinferred from corals or large molluscs in washover deposits and dunesup to 1 km inland, or from marine organisms attached to wave-emplaced boulders (scheffers et al., 2008, and references therein).these findings lack stratigraphic contexts, and uncertainties related toradiocarbon dating of reworked marine organisms (may et al., 2015a)or the marine palaeo-reservoir effect may bias the inferredchronologies.this paper provides, for the first time, detailed stratigraphicevidence of a prehistoric extreme-wave event from northwesternwestern australia. based on multi-proxy sediment and microfaunalanalyses,opticallystimulatedluminescence(osl)and14 c-dating,anal-lochthonous sand layer of marine origin was identified in a mud-filledback-barrier depression at the nw coast of the cape range peninsula.asa novel approach in thecontextof tsunamideposits, x-raycomputedmicrotomography (μct) scans of oriented cores reveal characteristicsediment fabrics, which have been described from modern (wassmeret al., 2010) and historical (cuven et al., 2013) tsunami deposits butare rarely preserved in palaeotsunami deposits. we discuss the originof the event layer against the background of its sedimentary character-istics and the local sedimentary environment.sedimentary geology 332 (2016) 40–50⁎ corresponding author.e-mail address: mays@uni-koeln.de (s.m. may).http://dx.doi.org/10.1016/j.sedgeo.2015.11.0100037-0738/© 2015 elsevier b.v. all rights reserved.contents lists available at sciencedirectsedimentary geologyjournal homepage: www.elsevier.com/locate/sedgeo