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3 results on '"Hellebrand, E W G"'

2. The P-T-t paths of high-grade gneisses, Kaoko Belt, Namibia: Constraints from mineral data, U-Pb allanite and monazite and Sm-Nd/Lu-Hf garnet ages and garnet ion probe data

Author

Jung, S, Brandt, S, Nebel, Oliver, Hellebrand, E W G, Seth, B, Jung, C, Jung, S, Brandt, S, Nebel, Oliver, Hellebrand, E W G, Seth, B, and Jung, C

Abstract

The Damara Orogeny is a late Neoproterozoic to Cambrian (ca. 570-480Ma) intracratonic event that affected the Kaoko Belt, the inland branch of the Damara orogen and the Gariep Belt in Namibia and South Africa. This study focuses on the Pan-African evoluti

Published
2014

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

Author

Blackman, D.K., Ildefonse, Benoit, John, Barbara, Ohara, Y., Miller, DJ, 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 Ronald, Früh‐Green, G., Fryer, P.B., Gee, J.S., Godard, M, Grimes, C.B., Halfpenny, Angela, Hansen, H.-E., Harris, A.C., Tamura, Akihiro, Hayman, Nicholas W, Hellebrand, E W G, Hirose, T., Hirth, J.G., Ishimaru, S., Johnson, K.T.M., Karner, G D, Linek, M., MacLeod, C.J., Maeda, J., Mason, O., McCaig, Andrew, Michibayashi, K, Morris, Antony, Nakagawa, T., Nozaka, T, Rosner, M., Searle, R C, Suhr, G., Tominaga, M., von der Handt, A., Yamasaki, T., Zhao, X., Blackman, D.K., Ildefonse, Benoit, John, Barbara, Ohara, Y., Miller, DJ, 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 Ronald, Früh‐Green, G., Fryer, P.B., Gee, J.S., Godard, M, Grimes, C.B., Halfpenny, Angela, Hansen, H.-E., Harris, A.C., Tamura, Akihiro, Hayman, Nicholas W, Hellebrand, E W G, Hirose, T., Hirth, J.G., Ishimaru, S., Johnson, K.T.M., Karner, G D, Linek, M., MacLeod, C.J., Maeda, J., Mason, O., McCaig, Andrew, Michibayashi, K, Morris, Antony, Nakagawa, T., Nozaka, T, Rosner, M., Searle, R C, Suhr, G., Tominaga, M., von der Handt, A., Yamasaki, T., and Zhao, X.

Abstract

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.

Published
2011

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