Skip to main content
Log in

Controls on greigite preservation in a gas hydrate system of the Krishna-Godavari basin, Bay of Bengal

  • Original
  • Published:
Geo-Marine Letters Aims and scope Submit manuscript

Abstract

Shallow sediments across large parts of Krishna-Godavari (K-G) basin offshore east central Indian contain abundant methane and gas hydrates. In this study, we carried out rock-magnetic and transmission electron microscope (TEM) analyses on the samples from a sediment core (MD161/Stn-8) to constrain the formation and preservation of greigite in shallow sediments and how this might link to reactions involving methane. Here, we report for the first time the occurrence of silicate-hosted iron sulfide (greigite) inclusions which is an important observation for understanding the preservation of magnetic minerals in gas hydrate systems. The magnetization of the greigite zone (17–23 mbsf) is carried by complex magnetic mineral assemblages of detrital iron oxides (titanomagnetite), diagenetic iron sulfide (greigite) occurring as nano-inclusions within larger silicate particles, and biogenic minerals. Elevated concentrations of dissolved pore water silica and alkalinity within the magnetically enhanced greigite zone suggest that silica diagenesis and silicate weathering triggered by paleo-methane seepage played a key role in crystallizing the diagenetically formed iron sulfide (greigite) into silicate matrix. The silicate-hosted magnetic inclusions protected the ferrimagnetic greigite from further diagenetic dissolution and prevented its conversion into stable pyrite. Three scenarios explaining the potential controls on the greigite preservation in gas hydrate marine sedimentary system have been proposed.

This is a preview of subscription content, log in via an institution to check access.

Access this article

Price excludes VAT (USA)
Tax calculation will be finalised during checkout.

Instant access to the full article PDF.

Fig. 1
Fig. 2
Fig. 3
Fig. 4
Fig. 5
Fig. 6
Fig. 7
Fig. 8

Similar content being viewed by others

Data Availability

The data used in this study can be made available upon email request to the corresponding author (firoz@nio.org). This is CSIR-NIO publication no. 6453.

References

Download references

Acknowledgments

We thank the Directors of CSIR-NIO, NCAOR, NIOT, advisor MOES, and NGHP (India) for supporting this study. We thank the head of oceanography department, and in-charge, onboard operations of IPEV are thanked for providing technical support and facilities onboard. We thank the students of Goa University, IIT Kharagpur, and the project scientists of NIO, NIOT, PRL, and NGRI. We thank Dr. Mike Jackson, Institute for Rock Magnetism (IRM), and the University of Minnesota, USA, for carrying out FORC measurements. We also thank the Director, Indian Institute of Geomagnetism (IIG), New Panvel, for providing permission to carry out magnetic measurements. We thank Professor B. R. Jagirdar, Indian Institute of Science, Bangalore, India, for providing support with TEM-EDS analysis. We thank T. Ramprasad and Dr. Brenda Mascarenhas for suggestions and timely inputs in this work.

Funding

This study was funded by SERB-DST, Government of India, under the scheme “Early Career Research Award (DST no: ECR/2016/000528) to Dr. Firoz Badesab. We sincerely acknowledge the comments from the editor (Dr. Andrew Green), associate editor (Dr. Gerald Dickens) and two reviewers (Dr. Liao Chang and anonymous).

Author information

Authors and Affiliations

Authors

Corresponding author

Correspondence to Firoz Badesab.

Ethics declarations

Conflict of interest

The authors declare that they have no conflict of interest.

Additional information

Publisher’s note

Springer Nature remains neutral with regard to jurisdictional claims in published maps and institutional affiliations.

Key Points:

• For the first time, we report the occurrence of silicate-hosted greigite inclusion and highlight its importance in understanding magnetic mineral diagenesis in gas hydrate systems.

• We propose that coupled silicate weathering and silica diagenesis triggered by AOM played an important role in the preservation of greigite occurring as inclusions in silicate minerals in a gas hydrate system of the Krishna-Godavari basin, Bay of Bengal.

• The present study unravels the complex magnetic mineral assemblages (detrital, diagenetic, biogenic) in a marine gas hydrate sedimentary system.

• We present rock-magnetic and geochemical signatures of diagenetic control of greigite production and preservation in a gas hydrate system of the Krishna-Godavari basin, Bay of Bengal.

• Three scenarios explaining the potential controls on the greigite preservation in gas hydrate marine sedimentary system are proposed.

Electronic supplementary material

ESM 1

(JPG 3310 kb)

ESM 2

(JPG 2034 kb)

Rights and permissions

Reprints and permissions

About this article

Check for updates. Verify currency and authenticity via CrossMark

Cite this article

Badesab, F., Gaikwad, V. & Dewangan, P. Controls on greigite preservation in a gas hydrate system of the Krishna-Godavari basin, Bay of Bengal. Geo-Mar Lett 40, 439–452 (2020). https://doi.org/10.1007/s00367-019-00604-z

Download citation

  • Received:

  • Accepted:

  • Published:

  • Issue Date:

  • DOI: https://doi.org/10.1007/s00367-019-00604-z

Navigation