Description: A transect of seafloor heat probe measurements on the Hikurangi Margin shows a significant increase of thermal gradients upslope of the pinchout of the base of gas hydrate stability. We attribute these anomalously high thermal gradients to a fluid pulse leading to advective heat flow while endothermic cooling from gas hydrate dissociation may arrest temperature gradients in the hydrate stability field. Double-bottom simulating reflections in the study area are likely to be caused by uplift based on gas hydrate phase boundary considerations. Previous studies predict a seamount on the subducting Pacific Plate to cause significant overpressure beneath our study area, which may be the source of the fluid pulse. We suggest this seamount may also cause the inferred uplift. Transient expulsion of warm fluids may lead to gas hydrate dissociation with potential implications for seafloor stability.

Description: Sand injections form by intrusion of overpressured, fluidized sand into surrounding low-permeable, fine-grained rocks. We conducted a series of scaled analog experiments to investigate the kinematic evolution of sand injections originating from an overpressured, tabular source layer associated with forced folding and propagation of fractures. The experiments were performed in the analog laboratory of the Institute of Geosciences (Friedrich Schiller University Jena) in the framework of the project "Mobilization of Unconsolidated Sediments Related to CO2 Storage". The layering of the analog materials consisted of non-cohesive and cohesive granulates to mimic a sand reservoir and its fine-grained overburden. To produce a fluid overpressure in the layered materials, air was injected from the base of the reservoir layer and additionally through a point-like needle valve penetrating into the reservoir layer. Pressure sensors recorded the air pressure at the base of the reservoir layer and in the needle valve. The experiments were monitored with a digital SLR camera and analyzed by the digital image correlation software DaVis 10.0 (LaVision GmbH) to calculate displacement and strain patterns in the analog materials. The data set presented here includes (1) original data: - Photos of the experimental evolution - Data of volumetric air flow rate and air pressure recorded during the experiments and (2) analyzed data: - Results of digital image correlation including edited photographs as well as data and plots of the displacement vector fields - Edited photos and a Python script for analyzing the vertical displacements of the experimental surface. Detailed descriptions of the experiments, method and results can be found in Warsitzka, et al. (2019) to which this data set is supplement.

Description: Forced folding of a low-permeable, competent sediment layer in response to magmatic sill intrusion, remobilisation of fluidized sand or fluid overpressure in underlying porous reservoir formations can cause the formation of complex fracture networks. The opening modes and geometries of these fractures affect the bulk permeability of the cover layer and, thus, are crucial for understanding fluid flow processes in sedimentary basins. We carried out analog experiments in the laboratory of the Institute of Geosciences, Friedrich Schiller University Jena (project: Mobilization of Unconsolidated Sediments Related to CO2 Storage) to simulate the evolution of fracture networks during forced folding, its differences between a 2D and 3D modelling approach and its variability depending on the rheological stratification of the cover. To produce a fluid overpressure in the layered analog materials, air was injected from the base of the layering and additionally through a point-like needle valve penetrating into the lowermost layer with a stepwise increasing air flux (Q). Pressure sensors recorded the air pressure at the base of the reservoir layer and in the needle valve. The experiments were monitored with a digital SLR camera and analyzed by the digital image correlation software DaVis 10.0 (LaVision GmbH) to calculate displacement and strain patterns in the analog materials. Furthermore, a fracture analysis was performed for which we measured length and dips or strikes, respectively, in the side view of the 2D experiments and in top view in the 3D experiments. Based on these data, opening modes of the fractures were determined and statistical analyses were applied. The outcomes of these analyses are shown in rose diagram and histograms. The data set presented here includes: 1) Original data: -PhotosOriginal.zip: Photos of the experimental evolution -FractureData.zip: Measured lengths and dips (from side views of the 2D experiments) or strikes (from top view of the 3D experiments) of individual fracture segments -PneumaticData.zip: Data of volumetric air flow rate (Q) and air pressure (P) recorded during the experiments 2) Analyzed data: -DigitalImageCorrelation.zip: Results of digital image correlation including edited photographs as well as data and plots of the displacement vector fields -SurfaceDisplacement.zip: Edited photos and a Python script for analyzing the vertical displacements of the experimental surface. -RoseDiagrams.zip: Rose diagrams plotting the dips or strikes, respectively, of the fracture segments -Histograms.zip: Histogram showing the abundance of fracture segments along the vertical z-axis in the 2D experiments or along the horizontal x and y axes in the 3D experiments Detailed descriptions of the experiments, method and results can be found in Warsitzka, et al. (2022) to which this data set is supplement.

Description: The development of bottom simulating reflectors (BSRs) and the gas hydrate stability zone (GHSZ) in continental margins is related to recent depositional and tectonic processes. This interrelation is important for understanding the potential resource of gas hydrate deposits. The purpose of this study is to understand the influence of such activity on the marine gas hydrate system of the seaward extension of the Trujillo Basin, Peru Margin. Here, we analyze near-seafloor heat flow probe data, high-resolution multichannel seismic (MCS) profiles, swath bathymetry and ocean floor observation system (OFOS) images. Based on our results, we identify three main physiographical subregions in the study area: (1) an area with turbidites, continuous BSRs and low-to-moderate near-seafloor heat flow (7-33 mW/m**2), (2) an area with sediment waves of turbidity origin, a mix of continuous and patchy BSRs, and moderate near-seafloor heat flow (26-39 mW/m**2), (3) an area with extensional faulting, patchy BSRs and moderate-to-high near-seafloor heat flow (52-110 mW/m**2). We conclude that sediment flow processes are the result of recent depositional controls, and faulting is the result of recent tectonic activity. Near-seafloor heat flow around chemoherms is moderate. Estimates of BSR-derived heat flow show differences to near-seafloor heat flow. This difference points to advection of fluids occurring at the seafloor. Alive Calyptogena and tube worms were observed in these venting zones. Based on our analysis, we conclude that: (1) recent depositional processes control the development of continuous BSRs and may restrict heat transfer through the GHSZ in the form of fluid venting at the seafloor, (2) recent tectonic processes control the development of patchy BSRs and allow heat transfer through the GHSZ along faults, which is manifested as fluid venting at the seafloor.