Occurrence of shallow gas in the easternmost Lago Fagnano (Tierra del Fuego)

Authors
Lodolo, Emanuele; Baradello, L.; Darbo, A.; Caffau, Mauro; Tassone, Alejandro Alberto; Lippai, Horacio Francisco; Lodolo, A.; De Zorzi, G.; Grossi, M.
Publication Year
2012
Language
English
Format
article
Status
Published version
Description
High-resolution seismic profiles acquired in the eastern sector of Lago Fagnano, the southernmost ice-free lake in the world, have shown the presence of very shallow gas-bearing layers in the upper sedimentary sequences. The gas-related features observed on seismic profiles include a typical, very strong reflection with reversed polarity, multiple reflections and acoustic blanking that hide subsurface sedimentary and structural features. The top of the acoustically high-amplitude layer is located between 0.3-1.7 m below the lake floor. It generally forms a sharp boundary, often marked by a varying offset probably due to different levels of gas penetration, which could be related to the lithology of the overlying sediments. To confirm the presence of gas, some gravity cores were recovered in places where the blanking effect was most relevant and in the supposed gas-free zone. Sediment core analyses have highlighted the occurrence of significant organic-rich components within the uppermost, largely unconsolidated sedimentary layers, in correspondence of the seismically-detected gassy zone, whereas only a few organic layers were found in the gas-free zone. We assume that the main origin of gas is linked to the presence of a shallow, thin peat-rich layer of Middle-Late Holocene age. In fact, the mapped gassy zone occurs in correspondence of the outlet of the Rio Turbio, the principal tributary of Lago Fagnano, which discharges waters coming from a relatively small sag pond located immediately to the east of the eastern shore of the lake. To date, this is the first evidence of shallow gas in Tierra del Fuego lakes.
Fil: Lodolo, Emanuele. Istituto Nazionale di Oceanografia e di Geofisica Sperimentale; Italia
Fil: Baradello, L.. Istituto Nazionale di Oceanografia e di Geofisica Sperimentale; Italia
Fil: Darbo, A.. Istituto Nazionale di Oceanografia e di Geofisica Sperimentale; Italia
Fil: Caffau, Mauro. Istituto Nazionale di Oceanografia e di Geofisica Sperimentale; Italia
Fil: Tassone, Alejandro Alberto. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Ciudad Universitaria. Instituto de Geociencias Básicas, Aplicadas y Ambientales de Buenos Aires. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Instituto de Geociencias Básicas, Aplicadas y Ambientales de Buenos Aires; Argentina. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Departamento de Geología. Instituto de Geofísica "Daniel Valencio"; Argentina
Fil: Lippai, Horacio Francisco. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Ciudad Universitaria. Instituto de Geociencias Básicas, Aplicadas y Ambientales de Buenos Aires. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Instituto de Geociencias Básicas, Aplicadas y Ambientales de Buenos Aires; Argentina. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Departamento de Geología. Instituto de Geofísica "Daniel Valencio"; Argentina
Fil: Lodolo, A.. Hydrotech. Area Science Park; Italia
Fil: De Zorzi, G.. Hydrotech. Area Science Park; Italia
Fil: Grossi, M.. Istituto Nazionale di Oceanografia e di Geofisica Sperimentale; Italia
Subject
Sismica
Gas
Lago Fagnano
Tierra del Fuego
Meteorología y Ciencias Atmosféricas
Ciencias de la Tierra y relacionadas con el Medio Ambiente
CIENCIAS NATURALES Y EXACTAS
Access level
Restricted access
License
https://creativecommons.org/licenses/by-nc-sa/2.5/ar/
Repository
CONICET Digital (CONICET)
Institution
Consejo Nacional de Investigaciones Científicas y Técnicas
OAI Identifier
oai:ri.conicet.gov.ar:11336/68243