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TICOSECT Experiment 3
TICOSECT Experiment 3 Description Experiment #3 shares the velocity and imaging goals of Experiments 1 and
2, but the circumstances are somewhat different. In this case the study area is on the
northern flank of the subducting Cocos Ridge. The current interpretation of the data (by
A. Stavenhagen, GEOMAR, 3-97) indicates that the crustal thickness of the subducting plate
here is ~11-12 km in contrast to normal, 6-7 km thick crust in areas 1 and 2. This
transect also encompasses an apparent lithological change or stratification in the
forearc. The outer Osa Peninsula and the nearby Cano Island are apparently composed
primarily of Eocene and younger accreted sediment [Baumgartner et al., 1989]. The current
interpretation also shows a distinct increase in "basement" velocity 10-15 km
landward of Cano Island, which supports the lithological change indicated by Baumgartner's
observations. The Cocos Plate dips at only ~17 degrees beneath the broad shelf platform
with an estimated depth of 22 km at the coastline.
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