Geochemistry of volcanic glass from Mahanadi offshore region, eastern continental margin of India: Constraints on the contribution of latest Toba super-eruption

The tephra layers in multiple sediment cores from the offshore region of the Mahanadi basin in the northern Bay of Bengal were investigated for possible volcanic sources. The glass shards from those tephra layers were studied for size distribution, texture, and elemental geochemistry to establish ch...

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Bibliographic Details
Published in:Acta oceanologica Sinica 2024-02, Vol.43 (2), p.111-119
Main Authors: Kocherla, Muralidhar, Ray, Durbar, Satyanarayanan, Manavalan, Joao, Hilda, Gaikwad, Virsen, Ramamurty, P. B.
Format: Article
Language:English
Subjects:
Ash layers
Ashes
Chondrites
Climatology
Composition
Continental margins
Cores
Earth and Environmental Science
Earth Sciences
Ecology
Engineering Fluid Dynamics
Environmental Chemistry
Eruptions
Geochemistry
Marine & Freshwater Sciences
Oceanography
Offshore
Quaternary
Silica
Silicon dioxide
Size distribution
Tephra
Trace elements
Volcanic activity
Volcanic eruptions
Volcanic glass
Volcanoes
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Summary:The tephra layers in multiple sediment cores from the offshore region of the Mahanadi basin in the northern Bay of Bengal were investigated for possible volcanic sources. The glass shards from those tephra layers were studied for size distribution, texture, and elemental geochemistry to establish chronostratigraphic markers for regional and global Quaternary correlation. The textural features of fine-grained (silty) volcanic glasses suggest the distal source of these tephra deposits. Major element composition with elevated SiO 2 contents ranging between 75%–76% and dominance of K 2 O (> 4.5%) over CaO (< 0.9%) suggest ashes have originated from siliceous rhyolitic melts, similar to the petrographic composition of tephra from the Toba volcano. The bulk trace element compositions of the same glass shards were comparable with those reported in the youngest Toba tephra reported elsewhere. Likewise, the LREE-dominated chondrite normalized REE profiles of tephra from the Mahanadi basin closely resemble the characteristic REE patterns in Toba ash from other parts of the Indian Ocean and thus confirmed the contribution of the youngest Toba super-eruption for this ash layers.
ISSN:0253-505X
1869-1099
DOI:10.1007/s13131-023-2195-5