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Published byAmber Tichenor Modified over 10 years ago
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Sea Level and Reefs in Hawaii
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Reefs
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30 0 N and 30 0 S, shallow sunlight seas
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Reef Types Barrier Reefs Fringing Reefs Atolls Patch Reefs
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Reef Evolution
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Methods Drilling Ecosystem surveys Dating (C 14 & U-series) Carbonate petrography
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Holocene reef and dune Leahi reef and dune Waimanalo reef and dune Waianae reef None recognized ? Kaena Stand ? Carbonate System of Oahu
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Ecosystem surveys Rotary cores
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Ecosystem surveys
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Wireline Drilling the Island Shelf
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Large, bottom shearing swell events govern the geologic record
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Low energy ~5-20 m Porites compressa branching Moderate energy ~2-8 m Porites lobata massive High energy ~0-2 m Porites lobata encrusting Shallow, high energy ~0-5 m Porolithon sp. High energy ~2-10 m Pocillopora meandrina stout branching Shallow, high energy ~0-10 m Montipora sp.
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LONO HARBOR HALE O LONO SITE: -High wave exposure -Sparse coral cover -Shore parallel ridge and runnel morphology HIKAUHI SITE -Medium wave exposure -Abundant coral cover -Shore normal spur and groove morphology HIKAUHI SITE HALE O LONO SITE High bed shear
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Modern Ecosystem Investigations: Results Modified from Storlazzi et al. (in press) Study Sites
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Modern Ecosystem Investigations: Results Modified from Storlazzi et al. (in press)
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Typical facies Branching coral framestone Encrusting coral-algal bindstone Mixed skeletal rubble Massive coral framestone Unconsolidated floatstone High energy Moderate energy Low energy
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Typical facies Rudstone BindstoneGrainstoneFramestoneWackestone
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Bindstone (algal pavement) Angular silt to pebble clasts (coral and algal) encrusted and bound by coralline algae, encrusting foraminifers and bryozoans; Extensive micritization of skeletal grains; Microcrystalline Mg- Calcite fills inter- and intraparticle pores
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Framestone (reef framework) Intraskeletal pores lined by aragonitic accicular cement; Pores filled by peloidal Mg- calcite grading out to silt- sized skeletal debris; Thick crusts of coralline algae, encrusting foraminifers (Homotrema, Planorbulina?), bryozoans and serpulids
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