Reutilisation of hydrothermal vent complexes for focused fluid flow on continental margins (Modgunn Arch, Norwegian Sea)

Chantelle Roelofse,Kamal’Deen O Omosanya,Tiago M Alves

doi:10.1111/bre.12507

Chantelle Roelofse, Kamal’Deen O Omosanya + Show 1 more

Open Access

https://doi.org/10.1111/bre.12507

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Abstract

AbstractConventional three‐dimensional (3D) seismic data reveal abundant igneous activity on the Modgunn Arch, mid‐Norwegian margin. Magmatic sills and associated hydrothermal vent complexes located at various depths prove the repeated utilisation of Paleocene‐Eocene magmatic conduits. In total, 125 sills and 85 hydrothermal vent complexes were identified and mapped, with vent complexes ranging in diameter from 300 to 3,100 m and sills from 0.5 to 50 km. Three examples of stacked vent complexes are presented, revealing large eruptions of hydrothermal fluids vertically through the same conduit, from sills to the palaeo‐sea floor. The vent complexes are found throughout Paleocene strata (66–56 Ma), whilst at least ten (10) vents were active during the Eocene. This study emphasises the importance of characterising ancient magmatic structures, as hydrothermal conduits and vent structures were, and may still be, reutilised as preferential fluid flow pathways to shallower strata. A minimum of four phases of hydrothermal vent complex formation are inferred. Cretaceous faults are both bypassed and used for magma and fluid flow. The reutilisation of magmatic structures here described may bring to light previously overlooked plays and renew interest in exploring magma‐rich continental margins.

Highlights

Magmatic activity in sedimentary basins has a critical impact on all five elements of a petroleum system: maturation of source rocks, fluid migration, reservoir rocks, seals and traps (Holford, Schofield, MacDonald, Duddy, & Green, 2012; Rohrman, 2007; Senger et al, 2017)
Three-dimensional (3D) seismic data were used in this study to interpret the relative timing and spatial distribution of intrusions and associated hydrothermal vent complexes on the Modgunn Arch
The main conclusions of this work are summarised as follows: 1. At least four phases of magmatic intrusions are interpreted by the diachroneity revealed by the hydrothermal vent complexes; 2

Summary

| INTRODUCTION

Magmatic activity in sedimentary basins has a critical impact on all five elements of a petroleum system: maturation of source rocks, fluid migration, reservoir rocks, seals and traps (Holford, Schofield, MacDonald, Duddy, & Green, 2012; Rohrman, 2007; Senger et al, 2017). Based on the stratigraphic position of upper terminations in the HTVCs, Hansen (2006) and Planke et al (2005) used the close relationship between the latter vent complexes and underlying sills to estimate the timing of sill intrusion They considered the North Atlantic Volcanic Province in the Vøring and Møre Basins to have been emplaced from the Paleocene to Eocene; the volcanic gases subsequently released from the HTVCs during this time are considered to be the cause of the major climate change event known as the Paleocene-Eocene Thermal Maximum (Aarnes, Planke, Trulsvik, & Svensen, 2015). The research questions of this study are as follows: 1. How many distinct magmatic events are recorded on the Modgunn Arch, and how extensive are these events on a magma-rich margin such as offshore mid-Norway?

Are hydrothermal vent complexes fed by specific types and depths of sills?

Findings

| CONCLUSIONS