Relations between methane venting, geological structure and seismo-tectonics in the Okhotsk Sea.

Obzhirov, A., Shakirov, R., Salyuk, A., Suess, Erwin, Biebow, Nicole and Salomatin, A. (2004) Relations between methane venting, geological structure and seismo-tectonics in the Okhotsk Sea. Geo-Marine Letters, 24 (3). pp. 135-139. DOI 10.1007/s00367-004-0175-0.

[thumbnail of Obzhirov.pdf] Text
Obzhirov.pdf - Published Version
Restricted to Registered users only

Download (2MB)

Supplementary data:

Abstract

Methane investigations carried out in the Okhotsk Sea show that the methane flux from the earth’s interior into the water column increased during periods of seismo-tectonic activity between 1988 and 2002. In this case, methane gas hydrates found on the northeast Sakhalin slope may have decomposed due to a reactivation of fault zones. Methane emissions in the Okhotsk Sea generally can be divided into two forms. Firstly, methane vents from decomposing gas hydrates and/or free gas exist below gas hydrate saturated sediments via fault zones, venting into the water column with high bubble concentrations that were recorded by echosounding. These hydro-acoustic anomalies were named “flares”. Methane concentration inside these flares reached 10,000–20,000 nl/l (background methane concentrations in the Okhotsk Sea are less than 90–100 nl/l). Secondly, methane migrates as seepage into the water column from oil- and gas-bearing sedimentary source rocks on the eastern Sakhalin shelf, without showing acoustic anomalies in the water column, probably by filtration and diffusion processes. In these areas methane concentration reached 500–3,000 nl/l. In seismo-tectonically active regions, like the northwestern part of the Okhotsk Sea, many new flares were observed. Their distribution and orientation are usually controlled by fault zones (East Sakhalin Shear Zone in the Okhotsk Sea).

Document Type: Article
Keywords: Methane venting, gas hydrates, tectonics, Okhotsk Sea, Sakhalin shelf
Research affiliation: OceanRep > SFB 574
OceanRep > GEOMAR > FB2 Marine Biogeochemistry > FB2-MG Marine Geosystems
OceanRep > SFB 574 > B6
Refereed: Yes
Open Access Journal?: No
Publisher: Springer
Projects: KOMEX
Contribution Number:
Project
Number
SFB 574
55
Date Deposited: 09 Mar 2009 14:35
Last Modified: 23 Sep 2019 22:46
URI: https://oceanrep.geomar.de/id/eprint/4157

Actions (login required)

View Item View Item