Isotopic composition of bank margin carbonates on Midway Atoll; amplitude constraint on post-early Miocene eustasy
Isotopic composition of bank margin carbonates on Midway Atoll; amplitude constraint on post-early Miocene eustasy
Geology (Boulder) (June 1983) 11 (6): 335-338
- aggradation
- atolls
- C-13/C-12
- carbon
- carbonate rocks
- Cenozoic
- changes of level
- cores
- cyclic processes
- diagenesis
- East Pacific Ocean Islands
- geochemistry
- isotopes
- lower Pliocene
- Midway
- Miocene
- Neogene
- O-18/O-16
- oceanography
- oxygen
- Pacific Ocean
- Pliocene
- processes
- reefs
- sedimentary rocks
- sedimentation
- stable isotopes
- stratigraphy
- Tertiary
- reef sedimentation
Continuously cored borehole. Subaerial exposure horizons are identified by light carbon isotope signatures. Sea-level highstands are recorded by aggradational units of reef sediment that are bounded by these subaerial exposure horizons. Sea-level lowstands are constrained to fall no farther than a meteoric-marine diagenetic boundary observed in the core. This diagenetic boundary is defined by an offset in both oxygen and carbon isotope data, light isotopic composition being indicative of intermittent meteoric diagenesis. These data constrain the amplitudes of three post-early Miocene glacio-eustatic sea-level falls to be no more than 32, 43, and 52 m. Absolute sea-level elevations are estimated by constructing a subsidence model.--Modified journal abstract.