Publications

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2015
Greene, JA, Tominaga M, Blackman DK.  2015.  Geologic implications of seafloor character and carbonate lithification imaged on the domal core of Atlantis Massif. Deep-Sea Research Part Ii-Topical Studies in Oceanography. 121:246-255.   10.1016/j.dsr2.2015.06.020   AbstractWebsite

We document the seafloor character on Atlantis Massif, an ocean core complex located at 30 degrees N on the Mid-Atlantic Ridge, with an emphasis on the distribution of carbonate features. Seafloor imagery, near-bottom backscatter, and bathymetry were analyzed on the Central Dome and the Western Shoulder of the exposed footwall to the detachment, and on the Eastern Block, a hanging wall to the fault. We merged Argo II still images to produce photo-mosaics and evaluated these together with video imagery, acoustic reflectivity, and basic rock composition. The seafloor was classified as unconsolidated sediment, lithified carbonate crust, consolidated carbonate cap, exposed basement, or rubble, and the spatial distribution of each type was assessed. Unconsolidated sediment, exposed basement, and rubble were documented in all three regions studied. Lithified carbonate crust was also present on the Western Shoulder and eastern Central Dome. Consolidated carbonate cap was found on the Eastern Block. The formation of the carbonate rock is interpreted to reflect precipitation and/or sediment cementation via fluids derived from serpentinization. Both processes occur at the nearby Lost City Hydrothermal Field. The newly documented locations of seafloor carbonate lithification therefore mark pathways of past, possibly recent, fluid flux from subsurface water-rock reaction zones and represent an additional constituent of the carbon cycling hosted by oceanic lithosphere. (C) 2015 Elsevier Ltd. All rights reserved.

2002
Blackman, DK, Karson JA, Kelley DS, Cann JR, Fruh-Green GL, Gee JS, Hurst SD, John BE, Morgan J, Nooner SL, Ross DK, Schroeder TJ, Williams EA.  2002.  Geology of the Atlantis Massif (Mid-Atlantic Ridge, 30°N): Implications for the evolution of an ultramafic oceanic core complex. Marine Geophysical Research. 23:443-469.   10.1023/b:mari.0000018232.14085.75   AbstractWebsite

The oceanic core complex comprising Atlantis Massif was formed within the past 1.5-2 Myr at the intersection of the Mid-Atlantic Ridge, 30degrees N, and the Atlantis Transform Fault. The corrugated, striated central dome prominently displays morphologic and geophysical characteristics representative of an ultramafic core complex exposed via long-lived detachment faulting. Sparse volcanic features on the massif's central dome indicate that minor volcanics have penetrated the inferred footwall, which geophysical data indicates is composed predominantly of variably serpentinized peridotite. In contrast, the hanging wall to the east of the central dome is comprised of volcanic rock. The southern part of the massif has experienced the greatest uplift, shoaling to less than 700 m below sea level, and the coarsely striated surface there extends eastward to the top of the median valley wall. Steep landslide embayments along the south face of the massif expose cross sections through the core complex. Almost all of the submersible and dredge samples from this area are deformed, altered peridotite and lesser gabbro. Intense serpentinization within the south wall has likely contributed to the uplift of the southern ridge and promoted the development of the Lost City Hydrothermal Field near the summit. Differences in the distribution with depth of brittle deformation observed in microstructural analyses of outcrop samples suggest that low-temperature strain, such as would be associated with a major detachment fault, is concentrated within several tens of meters of the domal surface. However, submersible and camera imagery show that deformation is widespread along the southern face of the massif, indicating that a series of faults, rather than a single detachment, accommodated the uplift and evolution of this oceanic core complex.

1988
Ballard, RD, Uchupi E, Blackman DK, Cheminee JL, Francheteau J, Hekinian R, Schwab WC, Sigurdsson H.  1988.  Geological mapping of the East Pacific Rise axis (10°19' -11°53'N) using the ARGO and ANGUS imaging systems. The Canadian Mineralogist. 26, Part 3:467-486., Ottawa, ON, Canada (CAN): Mineralogical Association of Canada, Ottawa, ON AbstractWebsite
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