Seismic and drilling constraints on velocity structure and reflectivity near IODP Hole U1309D on the central dome of Atlantis Massif, Mid-Atlantic Ridge 30°N
Collins, John A.
Blackman, Donna K.
Harris, Amber C.
Carlson, Richard L.
MetadataShow full item record
The seismic structure of the upper ∼1 km of the central dome of Atlantis Massif is investigated in the context of lithologies known from seafloor drilling and physical property measurements obtained within the borehole and on core samples. A new analysis of seafloor refraction data and multichannel reflection data acquired in the immediate vicinity of Integrated Ocean Drilling Program (IODP) Site U1309 was motivated by a discrepancy between initial seismic interpretations, which indicated mantle velocities at shallow depth, and the gabbroic sequence recovered by drilling. A new seismic velocity model is derived that is consistent with the full suite of geological and geophysical data in the central dome area; all of these data show that mafic intrusive rocks dominate the upper portion of the footwall of this oceanic core complex and that laterally extensive zones of ultramafic rocks are not required by the data. The origin of subseafloor reflectivity beneath the central dome was also considered. We find that seafloor scattering complicates the interpretation of multichannel seismic data acquired near Site U1309 but that detectable subsurface impedance contrasts do occur. Downhole variations in alteration may generate reflections observed from the upper kilometer of the central dome.
Author Posting. © American Geophysical Union, 2009. This article is posted here by permission of American Geophysical Union for personal use, not for redistribution. The definitive version was published in Geochemistry Geophysics Geosystems 10 (2009): Q01010, doi:10.1029/2008GC002121.
Showing items related by title, author, creator and subject.
Collins, John A.; Smith, Deborah K.; McGuire, Jeffrey J. (American Geophysical Union, 2012-10-09)At the oceanic core complex that forms the Atlantis Massif at 30°N on the Mid-Atlantic Ridge, slip along the detachment fault for the last 1.5–2 Ma has brought lower crust and mantle rocks to the seafloor. Hydroacoustic ...
Lower crustal variability and the crust/mantle transition at the Atlantis Massif oceanic core complex Blackman, Donna K.; Collins, John A. (American Geophysical Union, 2010-12-18)Seismic refraction data provide new constraints on the structure of the lower oceanic crust and its variability across the Atlantis Massif oceanic core complex, ∼30°N on the Mid-Atlantic Ridge. A 40 km-long spreading-parallel ...
Drilling constraints on lithospheric accretion and evolution at Atlantis Massif, Mid-Atlantic Ridge 30°N Blackman, Donna K.; Ildefonse, Benoit; John, Barbara E.; Ohara, Y.; Miller, D. J.; Abe, N.; Abratis, M.; Andal, E. S.; Andreani, Muriel; Awaji, S.; Beard, J. S.; Brunelli, D.; Charney, A. B.; Christie, D. M.; Collins, John A.; Delacour, A. G.; Delius, H.; Drouin, M.; Einaudi, F.; Escartin, Javier E.; Frost, B. R.; Fruh-Green, G. L.; Fryer, P. B.; Gee, Jeffrey S.; Grimes, C. B.; Halfpenny, A.; Hansen, H.-E.; Harris, Amber C.; Tamura, A.; Hayman, Nicholas W.; Hellebrand, Eric; Hirose, T.; Hirth, Greg; Ishimaru, S.; Johnson, Kevin T. M.; Karner, G. D.; Linek, M.; MacLeod, Christopher J.; Maeda, J.; Mason, O..U.; McCaig, A. M.; Michibayashi, K.; Morris, Antony; Nakagawa, T.; Nozaka, T.; Rosner, Martin; Searle, Roger C.; Suhr, G.; Tominaga, Masako; von der Handt, A.; Yamasaki, T.; Zhao, X. (American Geophysical Union, 2011-07-19)Expeditions 304 and 305 of the Integrated Ocean Drilling Program cored and logged a 1.4 km section of the domal core of Atlantis Massif. Postdrilling research results summarized here constrain the structure and lithology ...