John Mahoney
SOEST, University of Hawaii
September 9, 2004
Knowledge of volcanic oceanic plateaus remains at a much more rudimentary level than for continental LIPs. Plateaus are generally located in remote areas, and their igneous basement is difficult to sample because it is not only submerged but usually lies buried beneath a thick cover sequence of submarine sediments. Thus, the only effective way to sample basement crust in most plateaus is by drilling. Systematic drilling and detailed geophysical surveys are likely to provide the greatest future advances in understanding. The importance of drilling oceanic plateaus is emphasized in the recent Initial Science Plan of the IODP (International Ocean Drilling Program; see www.isas-office.jp). Objectives of particularly broad interest are to understand the mantle sources and processes that create these enormous magmatic features, and to establish the effects of plateau emplacement on climate and the biosphere.
That plateau drilling is alive and well (though mainly in the planning stage) is demonstrated by several proposals that are currently working their way through the IODP review and panel system. Note that for most of these proposals, abstracts outlining their goals and strategy can be found at the above web-site.
Magellan Rise and Manihiki Plateau (Erba et al.)
Hikurangi Plateau (Mortimer et al.)
Ontong Java Plateau and surrounding areas (Neal et al.)
Shatsky Rise (Sager et al.)
Recent surveys of plateaus include a successful mapping and dredging cruise to the Danger Islands Troughs of the Manihiki Plateau, conducted in August-September 2003 aboard the Japanese research vessel Hakuho-Maru (Nakanishi and Coffin, co-chiefs). A Japanese-funded multichannel seismic-reflection and mapping survey of part of the Ontong Java Plateau will take place early in 2005 (Coffin, chief scientist).
In addition to plateau drilling, several LIP-related IODP proposals seek to drill major seamount chains or present-day hotspots; another proposes drilling to investigate the Cretaceous-Paleogene boundary impact crater.
Louisville seamount trail (Koppers et al.)
Iceland hotspot (Murton et al.)
Indian Ocean hotspot seamounts (Sager et al.)
Chicxulub impact crater (Morgan et al.)