Sea Level and Reefs in Hawaii

Reefs

300 N and 300S, shallow sunlight seas

Reef Types

•Barrier Reefs•Fringing Reefs•Atolls•Patch Reefs

Reef Evolution

Methods

• Drilling

• Ecosystem surveys

• Dating (C14 & U-series)

• Carbonate petrography

Holocene reef and dune

Leahi reef and dune

Waimanalo reef and dune

Waianae reef

None recognized

?Kaena Stand?

Carbonate System of Oahu

Ecosystem surveys

Rotary cores

Ecosystem surveys

Wireline Drilling the Island Shelf

Large, bottom shearingswell events governthe geologic record

Low energy~5-20 m

Porites compressabranching

Moderate energy~2-8 m

Porites lobatamassive

High energy~0-2 m

Porites lobataencrusting

Shallow, high energy~0-5 m

Porolithon sp.

High energy~2-10 m

Pocillopora meandrinastout branching

Shallow, high energy~0-10 m

Montipora sp.

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 SITEHALE O LONO SITE

High bed shear

Modern Ecosystem Investigations: Results

Modified from Storlazzi et al. (in press)

Study Sites

Modern Ecosystem Investigations: Results

Modified from Storlazzi et al. (in press)

Typical facies

Branching coral

framestone

Encrustingcoral-algalbindstone

Mixedskeletalrubble

Massivecoral

framestone

Unconsolidatedfloatstone

High energy Moderate energy Low energy

Typical facies

Rudstone Bindstone Grainstone Framestone Wackestone

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

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