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Sea Level and Reefs in Hawaii. Reefs 30 0 N and 30 0 S, shallow sunlight seas.

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Presentation on theme: "Sea Level and Reefs in Hawaii. Reefs 30 0 N and 30 0 S, shallow sunlight seas."— Presentation transcript:

1 Sea Level and Reefs in Hawaii

2 Reefs

3 30 0 N and 30 0 S, shallow sunlight seas

4 Reef Types Barrier Reefs Fringing Reefs Atolls Patch Reefs

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9 Reef Evolution

10 Methods Drilling Ecosystem surveys Dating (C 14 & U-series) Carbonate petrography

11 Holocene reef and dune Leahi reef and dune Waimanalo reef and dune Waianae reef None recognized ? Kaena Stand ? Carbonate System of Oahu

12 Ecosystem surveys Rotary cores

13 Ecosystem surveys

14 Wireline Drilling the Island Shelf

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16 Large, bottom shearing swell events govern the geologic record

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19 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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21 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

22 Modern Ecosystem Investigations: Results Modified from Storlazzi et al. (in press) Study Sites

23 Modern Ecosystem Investigations: Results Modified from Storlazzi et al. (in press)

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25 Typical facies Branching coral framestone Encrusting coral-algal bindstone Mixed skeletal rubble Massive coral framestone Unconsolidated floatstone High energy Moderate energy Low energy

26 Typical facies Rudstone BindstoneGrainstoneFramestoneWackestone

27 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

28 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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