Abstract
Magnetostratigraphic results are reported from a core penetrating the top 100 m of Mururoa atoll, French Polynesia. The sequence of polarity reversals, based on relative up-down direction in the unoriented core, is correlated to the geomagnetic polarity time-scale from the Gauss (early Pliocene) through the Brunhes chron (late Pleistocene-Holocene). The polarity sequence is matched with the help of an early Brunhes radiometric date in a nearby core and the projected level of Gephyrocapsa oceanica (mid-Brunhes) from an adjacent inclined core. Rock-magnetic tests and extraction of magnetic components suggest a mixture of single- and multi-domain magnetite or maghemite carries the magnetic remanence. Newly refined atoll chronostratigraphy indicates a punctuated growth history and variable sedimentation rate of the reefal rim. Magnetostratigraphically dated periods of low accumulation correspond well with the increased frequency of subaerial exposure horizons. These new data suggest that third-order scale (1 m.y.) sea-level events are recorded in reefal deposits on moderate to slowly subsiding atolls. Mururoa and the Bahamian island of San Salvador have similar accumulation curves suggesting a global eustatic control.
Sign-in/Register to access full text options 
Free) 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
