Variations in pockmark composition at the Vestnesa Ridge: Insights from marine controlled source electromagnetic and seismic data - Archive ouverte HAL Accéder directement au contenu
Article Dans Une Revue Geochemistry, Geophysics, Geosystems Année : 2017

Variations in pockmark composition at the Vestnesa Ridge: Insights from marine controlled source electromagnetic and seismic data

Bedanta K. Goswami
  • Fonction : Auteur
Karen A. Weitemeyer
  • Fonction : Auteur
Stefan Bunz
  • Fonction : Auteur
Timothy A. Minshull
  • Fonction : Auteur
Graham Westbrook
  • Fonction : Auteur
Stephan Ker
Martin C. Sinha
  • Fonction : Auteur

Résumé

The Vestnesa Ridge marks the northern boundary of a known submarine gas hydrate province in the west Svalbard margin. Several seafloor pockmarks at the eastern segment of the ridge are sites of active methane venting. Until recently, seismic reflection data was the main tool for imaging beneath the ridge. Coincident controlled source electromagnetic (CSEM), high-resolution two-dimensional (2D) airgun, sweep frequency SYSIF and three-dimensional (3D) p-cable seismic reflection data were acquired at the south-eastern part of the ridge between 2011 and 2013. The CSEM and seismic data contains profiles across and along the ridge, passing several active and inactive pockmarks. Joint interpretation of resistivity models obtained from CSEM and seismic reflection data provides new information regarding the fluid composition beneath the pockmarks. There is considerable variation in transverse resistance and seismic reflection characteristics of the gas hydrate stability zone (GHSZ) between the ridge flanks and chimneys beneath pockmarks. Layered seismic reflectors on the flanks are associated with around 300Ωm2 transverse resistance, whereas the seismic reflectors within the chimneys exhibit amplitude blanking and chaotic patterns. The transverse resistance of the GHSZ within the chimneys vary between 400 and 1200 Ωm2. Variance attributes obtained from the 3D p-cable data also highlight faults and chimneys, which coincide with the resistivity anomalies. Based on the joint data interpretation, widespread gas hydrate presence is likely at the ridge, with both hydrates and free gas contained within the faults and chimneys. However, at the active chimneys the effect of gas likely dominate the resistive anomalies.

Dates et versions

hal-04201839 , version 1 (11-09-2023)

Identifiants

Citer

Bedanta K. Goswami, Karen A. Weitemeyer, Stefan Bunz, Timothy A. Minshull, Graham Westbrook, et al.. Variations in pockmark composition at the Vestnesa Ridge: Insights from marine controlled source electromagnetic and seismic data. Geochemistry, Geophysics, Geosystems, 2017, 18 (3), pp.1111-1125. ⟨10.1002/2016GC006700⟩. ⟨hal-04201839⟩
5 Consultations
0 Téléchargements

Altmetric

Partager

Gmail Facebook X LinkedIn More