Shallow gas charged sediments off the Indian west coast: Genesis and distribution

Mazumdar, Aninda; Peketi, A.; Dewangan, P.; Badesab, Firoz; Ramprasad, T.; Ramana, M.V.; Patil, D. J.; Dayal, A. M.

doi:10.1016/j.margeo.2009.09.005

Cited by 40 publications

(12 citation statements)

References 72 publications

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“…Higher alteration values are noticed in a patch between Mumbai and Mormugao and also between Mangalore and Kannur. literature (Fontugne and Duplessy 1986;Agnihotri et al 2003;Mazumdar et al 2009 andCowie et al 2009). Though, δ 13 C values of all the samples depict marine signature, comparatively higher values are seen off Gujarat (POR, DWA and VER) possibly because of C-4 vegetation sources on land, vegetation consistent with soil type and source terrain geology.…”

Section: Discussionmentioning

confidence: 99%

“…Fontugne and Duplessy (1986) reported -26‰ for riverine particulate organic matter and -20‰ for marine source. We have compiled the earlier literature values of δ 13 C in sediments from the Arabian Sea (from Fontugne and Duplessy 1986;Agnihotri et al 2003, Mazumdar et al 2009and Cowie et al 2009) and plotted along with our data in Fig. 8a.…”

Section: And N Content and Their Isotopic Signatures: Has Provenancmentioning

confidence: 99%

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Geochemical and Isotopic Signatures of Surficial Sediments from the Western Continental Shelf of India: Inferring Provenance, Weathering, and the Nature of Organic Matter

Kurian¹,

Nath²,

Kumar³

et al. 2013

Journal of Sedimentary Research

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suggested that the sediments are moderately weathered despite the intense orographic rainfall in the source area. Variability in degree of chemical weathering is seen with the change in provenance. In general, the sediments north of Goa with a provenance of Deccan basalts show higher chemical weathering index. C org /N molar ratios (range = 6.9 and 14) are mostly between 10 and 12 which are closer to marine organic matter values. This is corroborated by marine δ 13 C values (-18.2 to-21.6‰). While, they broadly fall within the marine values, heavier values are seen in northern transects off Porbandar and Dwaraka where the sediments have a provenance different from those in the south. This could be due to a higher contribution from C-4 type vegetation in the north, consistent with heavier δ 13 C values in terrestrial plants in source regions. Comparatively heavier δ 15 N values are observed for the northern transects (north of Ratnagiri) which is supported by the intense denitrification in the northern Arabian Sea.

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Section: Discussionmentioning

confidence: 99%

Section: And N Content and Their Isotopic Signatures: Has Provenancmentioning

confidence: 99%

Geochemical and Isotopic Signatures of Surficial Sediments from the Western Continental Shelf of India: Inferring Provenance, Weathering, and the Nature of Organic Matter

Kurian¹,

Nath²,

Kumar³

et al. 2013

Journal of Sedimentary Research

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“…These results indicate that the top of the acoustic blanking zone matches the development of the sulfate-methane transition zone (SMTZ). Mazumdar et al (2009) also reported that the gas front closely matched SMTZ in the central west coast of India.…”

Section: Correlation Between the Top Reflections Of The Acoustic Blanmentioning

confidence: 67%

Factors determining the spatial distribution of gas-charged sediments in the continental shelf off southeastern Korea

Chun

Ryu

Lee³

et al. 2012

Marine Geology

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“…An example is the feature type known as Acoustic Cover, which HOVLAND andJUDD (1988) andMAZUMDAR et al (2009) classified as Acoustic Blanking or Acoustic Masking and JENSEN and BENNIKE (2009), MISSIAEN et al (2002), DUARTE et al (2007, GARCIA-GARCÍA et al (2007), EMEIS et al (2004), LEE et al (2005), ORANGE et al (2005 called Acoustic Blanking; TAYLOR (1992) and FRAZÃO and VITAL (2007) described them as Blankets, GARCIA-GIL et al (2002) as the Acoustic Blanket. The references show that there is an overlapping of names referring to the classification of the different features, with different names being used for similar accumulations.…”

Section: Discussionmentioning

confidence: 99%

Shallow gas seismic structures: forms and distribution on Santa Catarina Island, Southern Brazil

et al. 2016

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This paper presents the spatial distribution of shallow gas structures and classifies them on the basis of two different data sets of CHIRP seismic records, one from the Conceição Lagoon (CL) and the other from North Bay (NB), both on Santa Catarina Island, Southern Brazil. Side scan sonar data from the CL were used to facilitate the understanding. The sub bottom (SB) seismic data were processed and interpreted by means of the SeisPrho software, the side scan sonar (SSS) data by SonarWiz5 software and the spatial extension being measured with the help of GIS. The shallow gas structures were defined in accordance with their shapes in the seismic recordings (echo-character). At the CL, shallow gas accumulations were found in the form of seepages and features presenting shallow gas structures between the surface and 8.20 ms (around 12.3 m). Accumulations of gas were found in the form of Acoustic Blanking with Acoustic Plume, and also Black Shadows. Pockmarks were found on the lagoon floor and associated with gas seepages (average size diameter 0.97 ± 0.19 m and density from 54 to 242 units per 50 m2). In the NB three types of shallow gas features were found in the seismic profile, namely Acoustic Blanking, Turbidity Pinnacles and Intra-sedimentary plumes. The depth varied from the surface to 12.10 ms (around 18.15 m). In both environments, the gas is escaping from the sediment into the water column. The Pockmarks in the CL and the Acoustic Plume features and sediment rich in total sulfur in the NB validate these findings.

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Shallow gas charged sediments off the Indian west coast: Genesis and distribution

Cited by 40 publications

References 72 publications

Geochemical and Isotopic Signatures of Surficial Sediments from the Western Continental Shelf of India: Inferring Provenance, Weathering, and the Nature of Organic Matter

Geochemical and Isotopic Signatures of Surficial Sediments from the Western Continental Shelf of India: Inferring Provenance, Weathering, and the Nature of Organic Matter

Factors determining the spatial distribution of gas-charged sediments in the continental shelf off southeastern Korea

Shallow gas seismic structures: forms and distribution on Santa Catarina Island, Southern Brazil

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