Oxygen and carbon isotope study of the Niue Atoll carbonates, S. W. Pacific: implications for a Dorag dolomitization model

Conference · Tue Jan 01 00:00:00 EST 1985 · Geol. Soc. Am., Abstr. Programs; (United States)

OSTI ID:6069982

Socki, R A; Aharon, P

Much attention has been given to Dorag-type dolomitization in recent years. Rodgers et al. (1982) used this model to explain dolomitization of the Niue Atoll, S.W. Pacific. The authors present here results of an ongoing isotope study of limestones and dolomites from a 170 foot core of the Niue Atoll and show that under present geochemical conditions mixing zone dolomitization (i.e. Dorag) is unlikely. 0-18 values range from -4.0 percent per thousand to -6.5 percent per thousand (PDB) for limestone and +1.1 percent per thousand to +2.5 percent per thousand (PDB) for dolomite. C-13 values range from -5.9 percent per thousand to -2.0 percent per thousand (PDB) for limestone and +0.7 percent per thousand 2.0 percent per thousand (PDB) for dolomite. Meteoric water 0-18 in this region is estimated to range from -4.5 percent per thousand to 7.0 percent per thousand (SMOW) based on 0-18 analyses of surface and ground waters from neighboring Fiji islands. They show that under present conditions 0-18 enriched Niuean dolomites are not in isotopic equilibrium with a dolomitizing fluid in which meteoric water with the above 0-18 composition is a component. However, this does not preclude Dorag-type dolomitization of limestones at Niue under different geochemical conditions. Their estimates indicate that for Dorag-type dolomitization to have occurred at Niue paleo-precipitation must have been significantly enriched in 0-18. This contention is independently supported by isotope studies of contemporary insular phosphates from other mid-Pacific atolls (Aharon and Veeh, 1984).

• Research Organization: Louisiana State Univ. Baton Rouge (USA)
• OSTI ID: 6069982
• Report Number(s): CONF-8510489-
• Journal Information: Geol. Soc. Am., Abstr. Programs; (United States), Vol. 17; Conference: 98. annual meeting of the Geological Society of America, Orlando, FL, USA, 28 Oct 1985
• Country of Publication: United States
• Language: English

Related Subjects

58 GEOSCIENCES
CARBONATE ROCKS
CHEMICAL COMPOSITION
DIAGENESIS
ISOTOPE RATIO
DOLOMITE
PRECIPITATION
CARBON ISOTOPES
CHEMICAL REACTIONS
DISSOLUTION
EQUILIBRIUM
GEOCHEMISTRY
GEOLOGIC MODELS
OXYGEN ISOTOPES
PETROGENESIS
ALKALINE EARTH METAL COMPOUNDS
CALCIUM CARBONATES
CALCIUM COMPOUNDS
CARBON COMPOUNDS
CARBONATE MINERALS
CARBONATES
CHEMISTRY
ISOTOPES
MAGNESIUM CARBONATES
MAGNESIUM COMPOUNDS
MINERALS
OXYGEN COMPOUNDS
ROCKS
SEDIMENTARY ROCKS
SEPARATION PROCESSES
580400* - Geochemistry- (-1989)