Abstract
Abstract. Various Eocene hyperthermal events have been recorded from lignite sections of western India in the past decade. To infer the paleoenvironment, during a warm paleotropical climate of India, we have assessed multiple microfossil groups like pollen/spores, dinoflagellates and foraminifera from Early Eocene lignite mine sections from the Cambay (Surkha) and Barmer (Giral) basins and Middle Eocene sections from the Kutch Basin (Matanomadh and Panandhro mines) of western India. The Surkha and Giral sections exhibit a dominance of rainforest elements (Arengapollenites achinatus, Longapertites retipilatus), thermophilic mangrove palm Nypa and (sub)tropical dinoflagellate cyst Apectodinium, Cordosphaeridium and Kenleyia. This palynomorph assemblage is indicative of a marginal marine setting within a hot and humid climate. During the Middle Eocene, the diversity of dinocyst assemblage increased and a decrease in percentage of mangrove elements was observed in the Matanomadh and Panandhro mine sections of the Kutch Basin as compared to the Early Eocene sections of western India. Bloom of triserial planktic (Jenkinsina columbiana) and rectilinear benthic (Brizalina sp., Trifarina advena rajasthanensis) foraminifera indicates eutrophic conditions of deposition during the Late Lutetian–Early Bartonian in the lignite sections of the Kutch Basin which later changed to oligotrophic, open marine conditions towards the Bartonian (planktic E12 zone). This change to oligotrophic conditions coincides with a drastic increase in diversity of planktic foraminifera in the top portion of lignite mines of the Kutch Basin which may be correlated with the Kirthar–Wilson Bluff transgression event in the Bartonian observed across basins in India, Pakistan and Australia potentially linked to sea level rise around the Middle Eocene Climatic Optimum.
Highlights
1.1 General introductionThe Early and Middle Eocene exhibited a very warm climate, but towards the Late Eocene, the atmosphere cooled and shifted from hothouse to icehouse conditions (Zachos et al, 2001)
There has been a plethora of records studied from the high latitudes with respect to microfossils and their change in size, diversity and abundance to adapt to the Paleogene warming events, especially the deep-sea drilling projects which have provided insight into continuous stratigraphic records (Clay Kelly et al, 1996; Kelly et al, 1998; Thomas and Shackleton, 1996; Arenillas et al, 1999; Giusberti et al, 2009; Alegret et al, 2010; Stassen et al, 2012; Zachos et al, 2001)
We have addressed the similarities and differences observed in the paleodepositional and paleovegetational conditions from the Cambay, Kutch and Barmer basins during the tropical climate of the Early and Middle Eocene
Summary
1.1 General introductionThe Early and Middle Eocene exhibited a very warm climate, but towards the Late Eocene, the atmosphere cooled and shifted from hothouse to icehouse conditions (Zachos et al, 2001). The low-latitude records of the Paleogene which are stratigraphically continuous are comparatively sparse (Jaramillo et al, 2006, 2010; Zamagni et al, 2012; Pearson et al, 2001; Khanolkar and Saraswati, 2015; Cramwinckel et al, 2018; Naafs et al, 2018). Some of the low-latitude Eocene sections from Tanzania, India and Java have recently provided insight into temperatures in the tropics during the Eocene epoch (Evans et al, 2018). There is a need to produce robust records from well-preserved
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