Widespread mega-pockmarks imaged along the western edge of the Cocos Ridge

Author(s): Gibson, J. C.; Kluesner, J. W.; Silver, E. A.; Bangs, N. L.; McIntosh, K. D.
Author Affiliation(s): Primary:
University of California at Santa Cruz, Earth and Planetary Sciences, Santa Cruz, CA, United States
Other:
University of Texas at Austin, Institute for Geophysics, United States
Volume Title: AGU 2012 fall meeting
Source: American Geophysical Union Fall Meeting, Vol.2012; American Geophysical Union 2012 fall meeting, San Francisco, CA, Dec. 3-7, 2012. Publisher: American Geophysical Union, Washington, DC, United States
Note: In English
Summary: A large field (245km2) of 31 seabed mega-pockmarks was imaged between the Cocos Ridge and the Quepos Plateau on ∼16.5 Ma oceanic crust generated at the Cocos-Nazca spreading center. The imaged pockmarks represent only a fraction of the much larger pockmark field evident in 100 m grid cell bathymetry data secured from MGDS. The pockmarks are clustered around 1800-2100 mbsl and were mapped using EM122 multibeam sonar, a 3.5 kHz sub-bottom profiler, and 3D Multi-Channel Seismic (MCS) aboard R/V Marcus G. Langseth during the CRISP seismic survey (2011). Using a constrained swath width of 1.4 km, the increased sounding density facilitated bathymetry/backscatter to be gridded at 10m and 8m respectively. The diameter of the pockmarks varies from ∼1 km to ∼2 km with a relief range of ∼30-80 m, and average slopes of 15°. The MCS data also reveal older buried pockmarks in trench adjacent sediments. Small high-backscatter mounds occur within a subset of the pockmarks, which may indicate bioherms or carbonate banks above focused fluid flow conduits. Based on drilling results of DSDP Site 158 and ODP Site 1381, the pockmarks appear to be the result of paleo-differential advancement of a silica diagenetic front (opal-A to opal-CT). Although, the pockmarks may be erosional features sourced at depth from dewatering of sediments inter-bedded with igneous layers.
Year of Publication: 2012
Research Program: DSDP Deep Sea Drilling Project
IODP Integrated Ocean Drilling Program
Key Words: 07 Marine Geology and Oceanography; Cocos Ridge; Costa Rica Seismogenesis Project; DSDP Site 158; Deep Sea Drilling Project; East Pacific; Equatorial Pacific; IODP Site U1381; Integrated Ocean Drilling Program; Leg 16; Mid-ocean ridges; North Pacific; Northeast Pacific; Ocean floors; Pacific Ocean; Pockmarks
Coordinates: N082543 N082543 W0840928 W0840929
N063724 N063724 W0851412 W0851412
Record ID: 2015012515
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