The architecture of submarine monogenetic volcanoes – insights from 3D seismic data

Abstract

Many prospective sedimentary basins contain a variety of extrusive volcanic products that are ultimately sourced from volcanoes. However, seismic reflection-based studies of magmatic rift basins have tended to focus on the underlying magma plumbing system, meaning that the seismic characteristics of volcanoes are not well understood. Additionally, volcanoes have similar morphologies to hydrothermal vents, which are also linked to underlying magmatic intrusions. In this study, we use high resolution 3D seismic and well data from the Bass Basin, offshore southern Australia, to document 34 cone-and crater-type vents of Miocene age. The vents overlie magmatic intrusions and have seismic properties indicative of a volcanic origin: their moderate-high amplitude upper reflections and zones of "wash-out" and velocity pull-up beneath. The internal reflections of the vents are similar to those found in lava deltas, suggesting they are composed of volcaniclastic material. This interpretation is corroborated by data from exploration wells which penetrated the flanks of several vents. We infer that the vents we describe are composed of hyaloclastite and pyroclasts produced during submarine volcanic eruptions. The morphology of the vents is typical of monogenetic volcanoes, consistent with the onshore record of volcanism on the southern Australian margin. Based on temporal, spatial and volumetric relationships, we propose that submarine volcanoes can evolve from maars to tuff cones as a result of varying magma-water interaction efficiency. The morphologies of the volcanoes and their links to the underlying feeder systems are superficially similar to hydrothermal vents. This highlights the need for careful seismic interpretation and characterization of vent structures linked to magmatic intrusions within sedimentary basins.

Three‐Dimensional Seismic Imaging of Ancient Submarine Lava Flows: An Example From the Southern Australian Margin

“…The reflection is cut by a number of east‐west oriented normal faults, with downthrow of 15 − 60 m occurring on the southern side of the fault plane. The Base Dugong is also characterized folds that are up to 210 m in height and directly overly the magmatic intrusions situated within the Hammerhead and Wobbegong Supersequences (Jackson et al, ; Magee et al, ; Reynolds et al, ; Schofield & Totterdell, ). The folds tend to be of lower amplitude than the intrusion thickness, but their outlines extend approximately to the perimeter of the underlying intrusion (Jackson et al, ).…”

“…We found a blend involving the frequencies R 5 23, G 5 33, B 5 49 Hz clearly imaged lava flow morphology. The methods used to map the intrusions and their distribution is described in detail by Reynolds et al, (2017aReynolds et al, ( , 2017b.…”

The mechanisms underpinning Cenozoic intraplate volcanism in eastern Australia: Insights from seismic tomography and geodynamic modeling

“…Black lines indicate the approximate locations of Palaeozoic orogen boundaries [ Glen et al , ]. Although not shown, recent evidence points to the presence of early to middle Miocene lava fields south of the NVP in Bass Strait [ Reynolds et al , ].…”

“…Black lines indicate the approximate locations of Palaeozoic orogen boundaries [Glen et al, 2016]. Although not shown, recent evidence points to the presence of early to middle Miocene lava fields south of the NVP in Bass Strait [Reynolds et al, 2017]. convection in the upper mantle, the composition of erupted material, and the pathway(s) taken by melt on route to the surface [e.g., Ashwal and Burke, 1989;King and Anderson, 1998;Huang et al, 2002].…”

In-context interpretation: Avoiding pitfalls in misidentification of igneous bodies in seismic data

“…In the San Jorge Basin, Argentina, exploration/ development wells targeting sand-prone meandering channels have drilled mafic lava flows with well-developed meander loops, filling a preexisting meander valley (Figure 3). In the Bass Basin, Australia, basaltic volcanoes were drilled by at least two exploration wells, which were originally intended to test the hydrocarbon potential of a Miocene "reef complex" at 790 m Reynolds et al, 2018;Figure 4).…”