- Dona Paula, Goa, India.
- +91-0832- 2450327
- iiosc2020[at]nio[dot]org
Abstract Submission No. | ABS-2022-13-0022 |
Title of Abstract | Magnetic tracking of source-to-sink processes |
Authors | Nitin Kadam*, Firoz Badesab, Virsen Gaikwad, B. Nagender Nath, Mahender Kotha, Lina Fernandes |
Organisation | CSIR-National Institute of Oceanography, Goa |
Address | A-8, CSIR-NIO Colony, Dona Paula, Panjim, Goa Panjim, Goa, India Pincode: 403004 Mobile: 7798319837 E-mail: nitinkadam7798@gmail.com |
Country | India |
Presentation | Oral |
Abstract | Magnetic minerals are ubiquitous in marine sedimentary system and are sensitive to environmental and geological processes. In this study, we employed rock magnetism, mineralogy, and granulometry methods on shelf sediment cores off Narmada (Arabian Sea), Ganga, and Penner (Bay of Bengal) Rivers to elucidate the sediment source-to-sink processes. Detrital (titanomagnetites, magnetites, hematite, and maghemite) and diagenetic (pyrite) minerals in varying proportion and grain sizes contribute to the bulk sediment magnetic record of the studied sediment cores. Thermomagnetic remanence curves revealed the presence of different magnetic mineral phases as seen through their distinct curie temperatures and intermediate mineral transformations. Magnetic grain size diagnostic proxy (Day Plot) confirmed the presence of single domain (SD), multidomain (MD), and pseudo single domain (PSD) grains. Electron microscopy observations on the magnetic particles exhibited distinct features linked with post-depositional influences including maghemitization and different degree of diagenetic alterations. Magnetogranulometry data showed a reversed relationship between magnetic and clastic grain size. In Narmada and Ganga River samples, the reversal is clearly noticed at medium silt (20-40 µm) fractions, whereas it occurs at fine silt (4-20 µm) for Penner shelf sediments. Such reversal is attributed to the presence of fine magnetic inclusions in host silicate fractions. In general, our multi-proxy data suggest that distinct geological sources, differential weathering and erosive conditions manifested by monsoon driven climatic changes at source regions and fluvial transport system generated variable sediment inputs and controlled the spatial distribution and enrichment of magnetic minerals in nearshore and shelf environment. Magnetic approach presented in this study provides valuable insights on how the magnetic signal exhibited by the bulk sediments and individual fractions can effectively be used to track the sediment provenance and sink (transport, deposition) processes in the geologically complex marine sedimentary systems. |