Data report: reconnaissance of bulk sediment composition and clay mineral assemblages: inputs to the Hikurangi subduction system

Abstract

Introduction 2 Methods 5 Results 15 Conclusions 16 Acknowledgments 16 References

Frictional and Lithological Controls on Shallow Slow Slip at the Northern Hikurangi Margin

“…Specifically, marls and chalk were found at 510–849 mbsf, and the lower portion of the sediment package (below 849 mbsf) consists of a volcaniclastic facies (Figure 2). The latter material contains basalt clasts, a clay‐rich (primarily saponite) altered matrix and zeolite cementation and, for a few tens of meters, carbonate‐rich cementation (Figure 2; Barnes et al., 2019; Underwood, 2020). Data from seismic reflection surveys (e.g., Bell et al., 2014) and regional drilling (Barnes et al., 2020) point to a plate interface which is likely patchy due to the heterogeneous incoming protolith containing regionally variable thicknesses of the carbonate and volcaniclastic sediments.…”

Cycling of CO2 and N2 Along the Hikurangi Subduction Margin, New Zealand: An Integrated Geological, Theoretical, and Isotopic Approach

“…Estimates for the composition of the Unit IV pelagic sequence are obtained from Barnes et al (2019) and are based on their reported mineral abundances (∼50% calcite, 30% clay, and 10% each quartz and feldspar; see Figure F5 in that article). Clay mineralogy is further separated based on powdered XRD analyses from Underwood (2020), and consists of ∼52% smectite, 37% illite, and 11% chlorite + kaolinite. The mineral abundances and idealized formulas for these minerals were used to estimate composition of the Unit IV pelagic sequence (Figure 3, Table 1).…”

Velocity‐Porosity Relations in Carbonate and Siliciclastic Subduction Zone Input Materials

“…Details about the data-collection methods can be found in Blum (1997) and the expedition reports (e.g., Harris et al, 2013;Henry et al, 2012;Jaeger et al, 2014;McNeill et al, 2017;Saito et al, 2010;Wallace et al, 2019). Additional XRD data, including information on the clay minerals, were obtained from published studies (Ikari et al, 2013(Ikari et al, , 2018Rosenberger et al, 2020;Screaton et al, 2017;Steurer & Underwood, 2003;Underwood, 2020;Underwood & Guo, 2013). As all analyses were not conducted on the same discrete samples, we identified the nearest neighbor measurements (always within 5 meters) on samples from the same lithologic unit and lithology.…”

“…This is not unexpected; ash in contact with seawater reacts to form hydrous clay minerals. In the case of samples from Hikurangi and Sunda, smectite is the dominant clay mineral (Rosenberger et al, 2020;Underwood, 2020). Smectite clays contain abundant interlayer water, accounting for up to 25% of the bulk mass (Brown & Ransom, 1996).…”