IODP Expeditions 304 & 305 Characterize the Lithology,Structure, and Alteration of an Oceanic Core Complex

Ildefonse, B.; Blackman, D.; John, B. E.; Ohara, Y.; Miller, D. J.; Macleod, C. J.; Abe, N.; Abratis, M.; Andal, E. S.; Andréani, M.; Awaji, S.; Beard, J. S.; Brunelli, Daniele; Charney, A. B.; Christie, D. M.; Delacour, A. G.; Delius, H.; Drouin, M.; Einaudi, F.; Escartin, J.; Frost, B. R.; Fryer, P. B.; Gee, J. S.; Godard, M.; Grimes, C. B.; Halfpenny, A.; Hansen, H. E.; Harris, A. C.; Hasebe, A. T.; Hayman, N. W.; Hellebrand, E.; Hirose, T.; Hirth, J. G.; Ishimaru, S.; Johnson, K. T. M.; Karner, G. D.; Linek, M.; Maeda, J.; Mason, O. U.; Mccaig, A. M.; Michibayashi, K.; Morris, A.; Nakagawa, T.; Nozaka, T.; Rosner, M.; Searle, R. C.; Suhr, G.; Tominaga, M.; VON DER HANDT, A.; Yamasaki, T.; Zhao, X.

More than forty years after the Mohole Project (Bascom,1961), the goal of drilling a complete section through in situoceanic crust remains unachieved. Deep Sea Drilling Project– Ocean Drilling Program (DSDP-ODP) Hole 504B withinthe eastern Pacifi c (Alt et al., 1993) is the deepest hole everdrilled into ocean crust (2111 mbsf), but it failed to reachlower crustal plutonic rocks below the pillow basalts andsheeted dikes. IODP Expeditions 309 and 312 eventuallyrecovered the long-sought transition from sheeted dikes intounderlying gabbros by drilling into very fast-spreadingPacifi c crust (Wilson et al., 2006). The lithology and structureof oceanic crust produced at slow-spreading ridges areheterogeneous (e.g., Cannat et al., 1997) and offer uniquedrilling access to lower crust and upper mantle rocks. AfterODP Hole 735B penetrated 1500 m of gabbro at the SouthwestIndian Ridge (Dick et al., 2000), IODP Expeditions 304 and305 recently recovered just over 1400 m of little-deformed,gabbroic lower crust from a tectonic window along the slowspreading Mid-Atlantic Ridge.

IODP Expeditions 304 & 305 Characterize the Lithology,Structure, and Alteration of an Oceanic Core Complex / Ildefonse, B.; Blackman, D.; John, B. E.; Ohara, Y.; Miller, D. J.; Macleod, C. J.; Abe, N.; Abratis, M.; Andal, E. S.; Andréani, M.; Awaji, S.; Beard, J. S.; Brunelli, Daniele; Charney, A. B.; Christie, D. M.; Delacour, A. G.; Delius, H.; Drouin, M.; Einaudi, F.; Escartin, J.; Frost, B. R.; Fryer, P. B.; Gee, J. S.; Godard, M.; Grimes, C. B.; Halfpenny, A.; Hansen, H. E.; Harris, A. C.; Hasebe, A. T.; Hayman, N. W.; Hellebrand, E.; Hirose, T.; Hirth, J. G.; Ishimaru, S.; Johnson, K. T. M.; Karner, G. D.; Linek, M.; Maeda, J.; Mason, O. U.; Mccaig, A. M.; Michibayashi, K.; Morris, A.; Nakagawa, T.; Nozaka, T.; Rosner, M.; Searle, R. C.; Suhr, G.; Tominaga, M.; VON DER HANDT, A.; Yamasaki, T.; Zhao, X.. - In: SCIENTIFIC DRILLING. - ISSN 0934-4365. - STAMPA. - 3:(2006), pp. 4-11.