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doi:10.2204/iodp.proc.317.205.2014

Introduction

The primary objective of Integrated Ocean Drilling Program (IODP) Expedition 317 to the Canterbury Basin, South Island, New Zealand, was to sample and date clinoform seismic sequence boundaries and sample associated facies to establish eustatic amplitudes (see the “Expedition 317 summary” chapter [Expedition 317 Scientists, 2011a]). Recognition of seismic sequence boundaries within core requires integration of lithostratigraphy, biostratigraphy, sediment composition, physical properties, and geochemistry, as key surfaces (unconformities, maximum flooding surfaces, etc.; Catuneanu, 2006) can only be identified through a multiproxy investigation. Shipboard analyses indicated that shelf and upper slope strata at all sites contained recurring heterolithic facies assemblages in the uppermost strata that transitioned downcore into a more homogeneous strata (see the “Expedition 317 summary” chapter [Expedition 317 Scientists, 2011a]). Additionally, the margin seismic stratigraphy reveals a strongly along-margin transport in the Miocene–Pliocene that gradually becomes strongly across-margin during the higher amplitude eustatic cycles of the Pleistocene (Fulthorpe and Carter, 1991; Lu and Fulthorpe, 2004; Lu et al., 2003). The regional geology of South Island changes systematically along-margin, providing a means by which to petrologically differentiate (fingerprint) dispersal pathways active during different stages of stratal formation (Fig. F1). The Clutha River, which drains the Otago region south of the study area, has a dominantly schist provenance, with arkosic sand mainly composed of quartz, albite, muscovite, biotite, chlorite, and epidote sourced from the schist (Mackinnon, 1983; Mortimer and Roser, 1992; Shapiro et al., 2007). The major rivers west and north of the Expedition 317 drilling transect drain mainly Torlesse terrane, which is composed of graywacke-dominated turbidite sequences with quartzofeldspathic (both K-feldspar and plagioclase) sandstone, with some argillite and conglomerate and lesser amounts of lawsonite, prehnite, and pumpellyite (Adams and Kelley, 1998; Mortimer, 1993). We have conducted quantitative X-ray diffraction (qXRD) analysis on samples from the four sites drilled during Expedition 317 to provide constraints on sediment composition, which influences the observed lithostratigraphy, sequence stratigraphy, physical properties, and geochemistry. Because there is a strong contrast in the lithology of the potential sediment sources (Torlesse vs. Haast [Otago] schist), quantitative mineralogy also may provide insight into the sediment dispersal processes during margin formation (Andrews and Eberl, 2007; Andrews et al., 2010).

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