Reply to Comments by N. Sultan on “Sedimentation Controls on Methane‐Hydrate Dynamics Across Glacial/Interglacial Stages: An Example From International Ocean Discovery Program Site U1517, Hikurangi Margin”

Abstract

Screaton et al. (2019, https://doi.org/10.1029/2019GC008603) examined the role of sedimentation, sea level, and bottom water temperature (BWT) changes due to glaciation as drivers for the downward migration of the base of gas hydrate stability and gas hydrate formation. International Ocean Discovery Program (IODP) Site U1517 in the Hikurangi margin was used as a case study because data at this site document a marked increase in chloride over a broad depth range, which was attributed to recent gas hydrate formation. In a comment on Screaton et al.

Porosity and permeability evolution in the Tuaheni Landslide Complex at Hikurangi margin from IODP Sites U1517 and U1519

“…The base of the gas hydrate stability zone (BGHS) has been interpreted to occur ~162 mbsf prior to drilling (Gross et al, 2018;Barnes et al, 2019b;Screaton et al, 2019Screaton et al, , 2020 or between ~85 and 128 mbsf (Sultan, 2020). Indication for gas hydrate occurrence was only found in Unit V (Figure 4) (Barnes et al, 2019b;Screaton et al, 2019Screaton et al, , 2020Sultan, 2020).…”

“…At Site U1517, chloride data mark a zone in the preslide interval among ~135 and ~165 mbsf with gas hydrate saturation ranging 2%-68% (Barnes et al, 2019b), with the BGHS at ~162 mbsf (Screaton et al, 2019) (Figure 4). Sultan (2020) reinterpreted chloride anomalies and proposed a BGHS between 85 and 128 mbsf, although this is not supported by Screaton et al (2019Screaton et al ( , 2020. LWD data evidenced three intervals potentially hosting gas hydrates (green shaded zones on Figure 4) between ~112-114, ~117-121 and ~128-145 mbsf (Barnes et al, 2019b).…”