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The four well- defined, mature canyons of the Arguello Canyon system are here named Arguello Canyon A, Arguello Canyon B, Arguello Canyon C, and Arguello Canyon D, from north to south. Each of these canyons exhibits unique and similar head morphologies that suggest collapse structures. These heads all notch the distal edge of the continental shelf in about 100 meters depth of water. They are located near or over the southwestern margin of the Santa Maria Basin, a major hydrocarbon basin. Interestingly, the best-developed collapsed canyon head morphology is located at Arguello Canyon B, the closest canyon head to the Santa Maria Basin, and the least developed is located at Arguello Canyon D. The EM300 bathymetric images show that all four canyons have detritus lobes that flow down canyon from the heads; these appear to represent evacuated material from beneath the collapsed heads. Along the downslope margins of the canyons, down-dropped walls and slump material indicate sediment failures occur regularly downslope. These canyons are quite sinuous and it appears that these bends result from mid-slope canyon wall failure.
The two immature canyons that flank Arguello Canyon D appear to result from top-down sediment transport processes. This is best illustrated with the developing canyon head just northwest of Arguello Canyon C where a gully appears just beneath the broad V-shaped head feature.
The gully west of Arguello Canyon A appears to originate in an amphitheater-like feature composed of parallel and converging rilles. Linear depressions and mounds are aligned parallel and sub-parallel to the canyons and gullies. These are especially prominent in the vicinity of Arguello Canyon D. Authigenic carbonate deposits have been collected at the heads of some of these canyons. It is speculated that the collapse heads, rilles, depressions and mounds are fluid-induced, possibly by escaping gas and fluids associated with the offshore hydrocarbon-rich Santa Maria Basin.
Perspective view from the west
|Index Map||Arguello Canyon||Santa Barbara Basin||Rodriguez Seamount|