Data Report: Oedometer and Triaxial Tests of Sediment from the Chile Triple Junction

Deep-sea sediments deposited at or near an actively spreading mid-ocean ridge experience a distinctly different thermal history than sediments deposited in other marine geotectonic settings. For sediments of a given age the impact of high heat flow decreases with increasing distance from the ridge. This simple relation is superimposed in the active spreading ridge along the margin of Southern Chile—the Chile Triple Junction—by the process of sediment accretion. Both processes, heat flow and lateral thrusting, strongly modify the mechanical behavior of sediment accreted. The original intent was to study the mechanical state of accreted sediment recovered during Ocean Drilling Program (ODP) Leg 141, both unaltered and altered diagenetically by hydrothermal fluids, to differentiate the effects of thermal and mechanical diagenesis. The research program included high-pressure oedometer as well as triaxial testing to quantify the relative importance of both diagenetic processes for shear strength and consolidation behavior. Unfortunately, whole-round core samples available from Leg 141 appeared to be inadequately preserved and only a limited number of specimens could be used for mechanical testing. Therefore, most of the pre-cruise goals could not be attained. This paper reports the results of oedometer as well triaxial tests obtained from a restricted testing program.