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doi:10.2204/iodp.proc.317.203.2013

Introduction

During Integrated Ocean Drilling Program (IODP) Expedition 317, four sites were drilled along a mid-shelf to upper slope transect in the Canterbury Basin (New Zealand) (Fig. F1). The Canterbury Basin was targeted to study the complex interaction of tectonic and erosional processes with glacioeustatic change, which results in a high-frequency sedimentary record of depositional cyclicity from the late Miocene to recent (see the “Expedition 317 summary” chapter [Expedition 317 Scientists, 2011]).

A total of 19 seismostratigraphic sequence boundaries were recognized, but the interpretation of these erosional unconformities is limited due to time gaps caused by missing sediment that eroded at sequence boundaries. However, a nearly continuous sedimentary record is crucial for age-depth estimation, correlation of lithologic sequences among sites, and 2-D backstripping, among others. In intervals where “missing strata” are indicated, underestimation of sedimentation rates and thicknesses of lithologic sequences is unavoidable. This restricts the potential for interpretation of the sedimentary processes that control continental margin sedimentary cycles on the basis of a reconstructed initial sedimentary record.

One approach to bridging these gaps in the sedimentary record is the reconstruction of missing strata using the reaction of clayey sediments to changing overburden stresses. The consolidation characteristics of clayey sediments are determined by the maximum effective overburden stress that they have experienced since their deposition. This allows us to constrain the former overburden and ultimately the thicknesses of missing strata from geotechnical tests, specifically from uniaxial consolidation tests performed using oedometers. In the course of IODP expeditions, recent consolidation tests were successfully deployed to investigate the compression behavior, with respect to evaluating the stability of continental slopes (Long et al., 2008) or to understanding the role of lithologies within subduction zones (Dugan and Daigle, 2011; Guo et al., 2011; Hüpers and Kopf, 2012; Saffer et al., 2011). In this study, we present the results of the uniaxial consolidation tests to evaluate sediment dynamics on a tectonic and glacioeustatic controlled shelf.

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