Fault‐controlled fluid flow inferred from hydrothermal vents imaged in 3D seismic reflection data, offshore NW Australia

Abstract

Fluid migration pathways in the subsurface are heavily influenced by pre-existing faults. Although studies of active fluid-escape structures can provide insights into the relationships between faults and fluid flow, they cannot fully constrain the geometry of and controls on the contemporaneous subsurface fluid flow pathways. We use 3D seismic reflection data from offshore NW Australia to map 121 ancient hydrothermal vents, likely related to magmatic activity, and a normal fault array considered to form fluid pathways. The buried vents consist of craters up to 264 m deep, which host a mound of disaggregated sedimentary material up to 518 m thick. There is a correlation between vent alignment and underlying fault traces. Seismic-stratigraphic observations and fault kinematic analyses reveal that the vents were emplaced on an intra-Tithonian seabed in response to the explosive release of fluids hosted within the fault array. We speculate that during the Late Jurassic the convexupwards morphology of the upper tip-lines of individual faults acted to channelize ascending fluids and control where fluid expulsion and vent formation occurred. This contribution highlights the usefulness of 3D seismic reflection data to constraining normal fault-controlled subsurface fluid flow.

Variation in style of magmatism and emplacement mechanism induced by changes in basin environments and stress fields (Pannonian Basin, Central Europe)

“…The geometrical properties of hydrothermal mounds (e.g. total height, area, average volume) are comparable to other offshore examples (Magee et al, ; Planke et al, ). Hydrothermal mounds occur over sill terminations and/or fault tips: this character is similar to those examples observed in rifted margins (Holford et al, ; Planke et al, ).…”

“…Hydrothermal mounds occur over sill terminations and/or fault tips: this character is similar to those examples observed in rifted margins (Holford et al, ; Planke et al, ). In several cases, hydrothermal flows leading to mound formation were guided by faults or spatially connected to faults (Magee et al, ). The Pannonian examples clearly document such connections, while the NE‐SW trending chain of hydrothermal mounds (hm2‐hm6) occurs above Mid‐Miocene splay faults (Figure ).…”

Deeply buried ancient volcanoes control hydrocarbon migration in the South China Sea

“…Relatively slow and continuous growth of these folds is supported by the observations that related growth strata progressively thin towards the fold and do not onlap a discrete surface (Figures 4a and 7). Such fault-controlled magma ascent is consistent with the spatial and genetically relationships between volcanoes and faults in active and ancient sedimentary basins (e.g., Gaffney, Damjanac, & Valentine, 2007;Isola, Mazzarini, Bonini, & Corti, 2014;Mazzarini, 2007;Magee, Jackson, & Schofield, 2013;Magee, Duffy et al, 2016;Weinstein et al, 2017), and in numerical models (e.g., Le Corvec, Spörli, Rowland, & Lindsay, 2013;Maccaferri, Rivalta, Keir, & Acocella, 2014). 32-16.5 Ma).…”

Delineating the Exmouth mantle plume (NW Australia) from denudation and magmatic addition estimates

“…1), and most of the evidence on the presence of intrusives comes from seismicreflection data. Recently, indirect dating of vent structures associated with sill intrusion on the Exmouth Plateau and Exmouth subbasin yielded Late Jurassic ages (Rohrman, 2013;Magee et al, 2013Magee et al, , 2015, predating breakup, whereas McClay et al (2013) inferred Early Cretaceous ages for sills at the Cuvier breakup margin. The origin of the Exmouth Plateau intrusive sheets is most likely from the underlying high-velocity body ( Fig.…”