The Holocene gas system of the Ría de Vigo (NW Spain): Factors controlling the location of gas accumulations, seeps and pockmarks

Martínez-Carreño, Natalia; García‐Gil, Soledad

doi:10.1016/j.margeo.2013.07.012

Cited by 33 publications

(30 citation statements)

References 66 publications

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“…More coarse-grained sediments, in comparison with the Holocene highstand units, constitute the prograding sequences composing the margin. Such sediments could host fluidsproviding good conditions for their lateral migration [22]. The main trending direction of this front is similar to the one observed for the detected roughly E-W striking volcanic body, despite its location seems to have shifted southward (Figure 10).…”

Section: Degassing Featuressupporting

confidence: 77%

“…Laterally extensive fronts of acoustic turbidity may be related to fluid accumulation zones occurring in certain stratigraphic intervals or at certain depths. Fluid front morphologies have also been explained as related to pressure and bottom water temperature [3] or to sedimentary facies association and permeability [22]. An accurate description of the fluid front morphologies is a fundamental tool to unravel the origin of the observed venting structures in order to better understand the late Quaternary evolution of the Campania margin.…”

Section: Introductionmentioning

confidence: 99%

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Coastal Evolution, Hydrothermal Migration Pathways and Soft Deformation along the Campania Continental Shelf (Southern Tyrrhenian Sea): Insights from High-Resolution Seismic Profiles

et al. 2018

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Abstract:A closely spaced set of high-resolution Chirp-Sonar and Sparker profiles and swath bathymetric data was acquired in 2013 for the I-AMICA Project off the Volturno River mouth (Southern Tyrrhenian Sea) by the Istituto per l'Ambiente Marino Costiero (IAMC), National Research Council of Italy (CNR). The palaeo-topography of three key surfaces, represented by the bounding surfaces of the post-glacial lithosomes, was mapped by the interpolation of seismically detected reflectors. The morphology of the surface related to the Last Glacial Maximum (LGM) regression revealed the presence of fault linkages which defined a small-scale accommodation zone with an E-W trending interbasinal relative high. The observed set of oppositely dipping faults, NNWand ENE-directed, locally controlled the deposition of the paralic/deltaic bodies during the post-glacial rise in sea level, as testified by their wedge-shaped geometries and shifting depocentres. The deformation may be linked to the Campi Flegrei caldera collapse following the Neapolitan Yellow Tuff (NYT) eruption and aged 15 ka BP. The relevant thickness of the Transgressive System Tract (TST) testifies to an increased sediment yield and intense reworking in coastal areas, probably driven by the high volcanoclastic supply during volcanic paroxysm, almost coeval with the post-glacial transgression. Fluid escape features linked to an E-W striking fluid front at the outer shelf suggest the presence of an hydrothermal system controlled by the predominant direction of normal to oblique Quaternary-active faults and by lithologic discontinuities across the sedimentary pile.

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Section: Degassing Featuressupporting

confidence: 77%

Section: Introductionmentioning

confidence: 99%

Coastal Evolution, Hydrothermal Migration Pathways and Soft Deformation along the Campania Continental Shelf (Southern Tyrrhenian Sea): Insights from High-Resolution Seismic Profiles

et al. 2018

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“…Seismic surveys in aquatic environments are often hampered by gas saturation of the upper layers, which significantly attenuates high‐frequency acoustic signals (Fleischer et al ; Judd ; Baltic Gas ). In marine embayments, mud‐filled basins, and lacustrine settings, the top of the gas saturation zone ( gas front , Judd and Hovland ) is typically situated at shallow depths (few metres to few tens of metres below sea/lake bottom), and the gas principally consists of biogenic methane (e.g., Taylor ; Judd and Hovland ; Baltzer et al ; Martínez‐Carreño and García‐Gil ; Tóth ). This methane

({CH}_{4})

is generated by methanogenic bacteria (Judd and Hovland ), and its production is regulated by environmental conditions and the availability of organic matter and limiting nutrients.…”

Section: Introductionmentioning

confidence: 99%

Seismic expressions of shallow gas in the lacustrine deposits of Lake Balaton, Hungary

Visnovitz

Bodnár

Tóth

et al. 2015

Near Surface Geophysics

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Lake Balaton, a large shallow lake in Central Europe (Hungary), has been the site of extensive ultra‐high‐resolution acoustic and multichannel seismic profiling in the period of 1997–2013. These surveys showed the widespread occurrence of shallow gas in the lake sediments and their immediate substrata. We analyzed about 2000 km of two‐dimensional profiles and mapped the different gas occurrences in the uppermost 20 m. The anomalies caused by free gas were identified, classified, and assigned to upper, middle and lower levels based on gas signatures and stratigraphic position. Monitoring of the uppermost gas front has revealed temporal variations between surveys from different years and seasons that manifested in the changes of free gas content in the upper two levels. Free gas in the lower part of the lake sediments and at around the base of the mud indicated greater stability. The different nature of the three free gas levels can be explained by vertical changes in quantity, production rate, and solubility of methane and carbon dioxide gases. We suggest that methane was derived from the microbial decomposition of organic matter in the mud and Pleistocene peat at the base of the mud, whereas CO2 is transported to the lower mud layers by upwelling fluids.

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“…Mixed siliciclastic and skeletal gravels prevail on the present sea floor both in the outer part of the ria and along the coastal margins, but clay and silt rich in organics and shallow methane gas dominate in the central and inner parts (e.g. Martínez‐Carreño & García‐Gil ). The intrusion of nutrient‐rich deep waters at the seabed during upwelling regimes increases biological productivity in the ria, consistently raising the flow of organic matter (OM) towards the sea floor.…”

Section: Settingsmentioning

confidence: 99%

“…); CS ‐6, CORE ‐8 (Muñoz Sobrino et al . ); B‐1; MRV ‐3 and MRV ‐4 (Martínez‐Carreño & García‐Gil ). C. Aerial view of the Cíes Islands (Galician Atlantic Islands Maritime‐Terrestrial National Park; source: Archives of the Galician Atlantic Islands Maritime‐Terrestrial National Park) with the location of the sites cited in the text, and also the lacustrine sediments studied in Costas et al .…”

mentioning

confidence: 99%

Reconstruction of the environmental history of a coastal insular system using shallow marine records: the last three millennia of the Cíes Islands (Ría de Vigo,NWIberia)

Sobrino

García-Moreiras

Martínez-Carreño

et al. 2016

Boreas

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The coastal lagoon‐beach complex at the Cíes Islands located at the opening of the Ría de Vigo (NW Iberia) is an important ecosystem currently threatened by anthropogenic impacts and climate variations. We used multiproxy marine sediment analyses to reconstruct the millennial environmental dynamics of this insular system and, in particular, the recent history of its coastal lagoon. Geophysical surveys were used to obtain bathymetry and identify the major sedimentary units of its closest submarine basin as well as their sediment sources. Core samples were taken in the middle and distal parts of the sedimentary body, where several prograding sedimentary units are thinner, allowing continuous sampling of the facies. Lithological, textural, elemental and chronological analyses were carried out on two cores. The detailed palynological studies on one of the cores included the analyses of the pollen, non‐pollen palynomorphs and dinocysts dating back three millennia. Our results revealed noticeable environmental changes affecting this area during the last 3000 years, due mainly to changing climate and oceanic conditions but also to the impact of historic human occupation of the islands. Several cold events (the 2.8 ka BP event and the Little Ice Age) characterized by enhanced upwelling alternated with warmer stormy periods of prevailing downwelling conditions in the ria. These circumstances altered the balance amongst the lacustrine, marsh, dune and lagoon systems, opening ephemeral inlets and modifying the trophic stage of the shallow waters surrounding the archipelago. Here we provide a background of the human and climatic impacts affecting these highly sensitive habitats, which may serve to improve their future management strategies.

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The Holocene gas system of the Ría de Vigo (NW Spain): Factors controlling the location of gas accumulations, seeps and pockmarks

Cited by 33 publications

References 66 publications

Coastal Evolution, Hydrothermal Migration Pathways and Soft Deformation along the Campania Continental Shelf (Southern Tyrrhenian Sea): Insights from High-Resolution Seismic Profiles

Coastal Evolution, Hydrothermal Migration Pathways and Soft Deformation along the Campania Continental Shelf (Southern Tyrrhenian Sea): Insights from High-Resolution Seismic Profiles

Seismic expressions of shallow gas in the lacustrine deposits of Lake Balaton, Hungary

Reconstruction of the environmental history of a coastal insular system using shallow marine records: the last three millennia of the Cíes Islands (Ría de Vigo,NWIberia)

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