Paleoenvironmental reconstruction of the Middle Jurassic rocks in western India using benthic foraminifera

The Middle Jurassic (Bajocian‒Callovian) benthic foraminifera in the Jhura Dome (Kachchh, Western India) were quantitatively analyzed to reconstruct the paleoenvironment. Three distinct assemblages are identified; these are dominated by a particular benthic foraminiferal species, and include, the mo...

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Bibliographic Details
Published in:Facies 2023-07, Vol.69 (3), Article 12
Main Authors: Jain, Sreepat, Alhussein, Mohamad, Ahmed, Mohamed S., Abdelhady, Ahmed Awad
Format: Article
Language:English
Subjects:
Bathymeters
Bathymetry
Benthos
Biogeosciences
Bottom water
Carbonates
Climate change
Distribution patterns
Earth and Environmental Science
Earth Sciences
Ecology
Foraminifera
Geochemistry
Jurassic
Nutrient availability
Nutrients
Original Article
Oxygen
Oxygenation
Paleontology
Sedimentary facies
Sedimentology
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Summary:The Middle Jurassic (Bajocian‒Callovian) benthic foraminifera in the Jhura Dome (Kachchh, Western India) were quantitatively analyzed to reconstruct the paleoenvironment. Three distinct assemblages are identified; these are dominated by a particular benthic foraminiferal species, and include, the moderately mesotrophic and well-oxygenated Protomarssonella poddari, moderately mesotrophic and moderately oxygenated Lenticulina subalata, and the highly mesotrophic and moderately oxygenated Epistomina mosquensis–Reophax metensis. Based on species bathymetry, an inner to middle neritic (50‒100 m) depth range is inferred for the studied section. The Bathonian is marked by a carbonate-dominated moderately mesotrophic regime, whereas the Callovian is siliciclastic-dominated and reflects highly mesotrophic conditions. The changes in facies and the trophic regime are attributed to a change in climate from a hot and drier Bathonian to a cooler and wetter Callovian with a progressive increase in the terrigenous input (= nutrient input) and in reduced oxygenation of bottom waters. The Canonical Correspondence Analysis yielded sea level, Benthic Foraminiferal Oxygen Index (BFOI) and paleoproductivity as the main factors controlling the distribution patterns of the studied benthic foraminifera. Additionally, within a shallow epeiric basin and in moderately to well-oxygenated bottom water conditions, the role of nutrients and oxygen availability overrides the influence of bathymetry that at the deeper settings, played a far greater role.
ISSN:0172-9179
1612-4820
DOI:10.1007/s10347-023-00668-5