Pore Water Geochemistry as a Tool for Identifying and Dating Recent Mass-Transport Deposits

Abstract

Several previous studies have shown that submarine mass-movements can profoundly impact the shape of pore water profiles. Therefore, pore water geochemistry and diffusion models were proposed as tools for identifying and dating recent (max. several thousands of years old) mass-transport deposits (MTDs). In particular, sulfate (SO 4 2− ) profiles evidentially indicate transient pore water conditions generated by submarine landslides. After mass-movements that

Sulfur Cycling in an Iron Oxide-Dominated, Dynamic Marine Depositional System: The Argentine Continental Margin

“…Predominantly terrigenous material, delivered from the numerous fluvial tributaries along the coast of Argentina and Uruguay (Iriondo, 1984;Piccolo and Perillo, 1999), is transported downslope from the continental shelf via gravity-controlled mass flows, including turbidity currents and density flows (Biscaye and Dasch, 1971;Klaus and Ledbetter, 1988;Sachs and Ellwood, 1988;Romero and Hensen, 2002;Hensen et al, 2003;Henkel et al, 2011Henkel et al, , 2012Gruetzner et al, 2012;Voigt et al, 2013). These mass flows also transport reworked organic matter further downslope, resulting in burial of refractory organic carbon (Hedges and Keil, 1995) in the deeper parts of the basin.…”

“…Rapid overall sedimentation is sometimes interrupted by phases of sediment winnowing caused by ocean currents. Episodic mass wasting processes can lead to instantaneous sediment accumulation (e.g., Hensen et al, 2003;Riedinger et al, 2005;Henkel et al, 2011Henkel et al, , 2012. These changes cause non-steady state conditions in the subsurface sediment/pore-water system (e.g., Kasten et al, 2003).…”

“…Shielded from sulfidic conditions in the upper sediment column due to rapid burial-and in the presence of mostly reworked, unreactive organic matter-those oxidized reactive iron phases are then preserved in deeper subsurface sediments März et al, 2008;Riedinger et al, 2014). The continental margin off Uruguay and Argentina is characterized by such highly dynamic depositional conditions (e.g., Riedinger et al, 2005;Henkel et al, 2011Henkel et al, , 2012Krastel et al, , 2013, and these locations are likely to be representative of environments that are common throughout the world along continental margins.…”

Constraining the Age and Evolution of the Tuaheni Landslide Complex, Hikurangi Margin, New Zealand, Using Pore‐Water Geochemistry and Numerical Modeling

“…The pore‐water record is very sensitive to recent perturbations such as changes in methane flux, organic carbon rain rate, and rapid sedimentary events (e.g., Chen et al, 2019; de Lange, 1983; Fischer et al, 2013; Henkel et al, 2011; Henkel et al, 2012; Hensen et al, 2003; Luo et al, 2015; Zabel & Schulz, 2001). In dynamic depositional settings, pore‐water species involved in early diagenetic processes can exhibit transient‐state features that hold a historical record of sediment perturbations.…”

“…In dynamic depositional settings, pore‐water species involved in early diagenetic processes can exhibit transient‐state features that hold a historical record of sediment perturbations. For instance, typical nonsteady‐state sulfate profiles (concave‐up, concave‐down, “S”‐type shapes) that developed in response to mass transport deposits (MTDs) have been observed in a variety of marine settings and have been used to constrain the age of the most recent event that disturbed the pore‐water profiles (Henkel et al, 2011; Henkel et al, 2012; Hensen et al, 2003; Hong et al, 2014; Zabel & Schulz, 2001). Dating such deposits can further be correlated to documented geological events (e.g., earthquakes), thereby shedding light upon the causal links among various geological processes (Henkel et al, 2011; Strasser et al, 2013).…”