Drilling constraints on lithospheric accretion and evolution at Atlantis Massif, Mid-Atlantic Ridge 30°N

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doi: 10.1029/2010JB007931
Author(s): Blackman, D. K.; Ildefonse, B.; John, B. E.; Ohara, Y.; Miller, D. J.; Abe, N.; Abratis, M.; Andal, E. S.; Andreani, M.; Awaji, S.; Beard, J. S.; Brunelli, D.; Charney, A. B.; Christie, D. M.; Collins, J.; Delacour, A. G.; Delius, H.; Drouin, M.; Einaudi, F.; Escartin, J.; Frost, B. R.; Früh-Green, G.; Fryer, P. B.; Gee, J. S.; Godard, M.; Grimes, C. B.; Halfpenny, A.; Hansen, H. E.; Harris, A. C.; Tamura, A.; Hayman, N. W.; Hellebrand, E.; Hirose, T.; Hirth, J. G.; Ishimaru, S.; Johnson, K. T. M.; Karner, G. D.; Linek, M.; MacLeod, C. J.; 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.
Author Affiliation(s): Primary:
Scripps Institution of Oceanography, La Jolla, CA, United States
Other:
Université Montpellier II, France
University of Wyoming, United States
Ocean Research Laboratory, Japan
Texas A&M University, United States
Japan Agency for Marine-Earth Science and Technology, Japan
Friedrich Schiller University of Jena, Germany
Philex Mining Corporation, Philippines
Université Claude Bernard Lyon I, France
University of Tokyo, Japan
Virginia Museum of Natural History, United States
Universita Modena, Italy
Oregon State University, United States
University of Alaska Fairbanks, United States
Woods Hole Oceanographic Institution, United States
Université Toulouse, France
University of Leicester, United Kingdom
Université Réunion, France
Institut de Physique du Globe, France
Eidgenössische Technische Hochschule Zürich, Switzerland
University of Hawaii at Manoa, United States
Mississippi State University, United States
Australian National University, Australia
University of Bergen, Norway
Norwich University, United States
Kanazawa University, Japan
University of Texas at Austin, United States
Brown University, United States
Exxon-Mobile, United States
Baker Hughes, United States
Cardiff University, United Kingdom
Hokkaido University, Japan
Lawrence Berkeley National Laboratory, United States
University of Leeds, United Kingdom
Shizuoka University, Japan
University of Plymouth, United Kingdom
Nihon University, Japan
Okayama University, Japan
GeoForschungsZentrum, Germany
Durham University, United Kingdom
Universitat zu Köln, Germany
University of Freiburg, Germany
University of California at Santa Cruz, United States
Volume Title: Journal of Geophysical Research
Source: Journal of Geophysical Research, 116(B7). Publisher: American Geophysical Union, Washington, DC, United States. ISSN: 0148-0227
Note: In English. 75 refs.; illus., incl. sects., 2 tables, geol. sketch map
Summary: 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 of the Central Dome of this oceanic core complex. The dominantly gabbroic sequence recovered contrasts with predrilling predictions; application of the ground truth in subsequent geophysical processing has produced self-consistent models for the Central Dome. The presence of many thin interfingered petrologic units indicates that the intrusions forming the domal core were emplaced over a minimum of 100-220 kyr, and not as a single magma pulse. Isotopic and mineralogical alteration is intense in the upper 100 m but decreases in intensity with depth. Below 800 m, alteration is restricted to narrow zones surrounding faults, veins, igneous contacts, and to an interval of locally intense serpentinization in olivine-rich troctolite. Hydration of the lithosphere occurred over the complete range of temperature conditions from granulite to zeolite facies, but was predominantly in the amphibolite and greenschist range. Deformation of the sequence was remarkably localized, despite paleomagnetic indications that the dome has undergone at least 45° rotation, presumably during unroofing via detachment faulting. Both the deformation pattern and the lithology contrast with what is known from seafloor studies on the adjacent Southern Ridge of the massif. There, the detachment capping the domal core deformed a 100 m thick zone and serpentinized peridotite comprises ∼70% of recovered samples. We develop a working model of the evolution of Atlantis Massif over the past 2 Myr, outlining several stages that could explain the observed similarities and differences between the Central Dome and the Southern Ridge.
Year of Publication: 2011
Research Program: IODP Integrated Ocean Drilling Program
Key Words: 18 Geophysics, Solid-Earth; 20 Geophysics, Applied; Accretion; Atlantic Ocean; Atlantis Massif; Cores; Crust; Expedition 304; Expedition 305; Expeditions 304/305; Gabbros; Geophysical methods; Geophysical surveys; IODP Site U1309; IODP Site U1310; IODP Site U1311; Igneous rocks; Integrated Ocean Drilling Program; Lithosphere; Magmatism; Mid-Atlantic Ridge; Mid-ocean ridges; North Atlantic; Ocean floors; Oceanic crust; Oceanic lithosphere; Plutonic rocks; Refraction methods; Seismic methods; Surveys; Tectonics
Coordinates: N301000 N301100 W0420600 W0420700
N301100 N301100 W0420400 W0420400
N301100 N301200 W0420400 W0420400
Record ID: 2012023645
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