Palaeogene isotopic temperatures of western India

Abstract

Oxygen isotopic measurements of larger benthic foraminifers from western India suggest that the Palaeogene temperature varied between 22deg;C and 32deg;C in this region. The warm climate of the Palaeocene and the Early Eocene, hovering around 32°C, deteriorated in late Middle Eocene (corresponding to planktic zones P13‐P14) when the temperature dropped by 6deg;C. With progressive cooling through the Late Eocene, the temperature reached 22deg;C during Early Oligocene times. The cooling trend set in the Middle Eocene seems to have been terminated towards the end of the Palaeogene when the temperature rose to 25°C. □Palaeotemperature, Palaeogene, oxygen isotopes, larger foraminifiers, India.

Saddle-shaped reticulate Nummulites from Early Oligocene rocks of Khari area, SW Kutch, India

“…clypeus (table 1). However, majority of subsequent researchers like Sastri et al (1964); Mohan (1965); Chatterji and Mathur (1966); Mohan and Gupta (1968); Raju et al (1970); Mohan and Pandey (1971); Mohan (1982); Samanta et al (1985); Samanta (1988); Biswas (1992); Saraswati (1995), Sarkar et al (1996); Saraswati et al (1993Saraswati et al ( , 1997 and Sarangi et al (1998) referred the Kutch reticulate Nummulites as N . fichteli.…”

Ecology of foraminifera during the middle Eocene climatic optimum in Kutch, India

“…The genera Nummulites, Operculina and Alveolina, which also occurred in Fulra Limestone, requires minimum temperatures of 24°C for survival (Langer & Hottinger, 2000). The oxygen isotopic analysis of foraminifera estimates that seawater temperatures during the formation of Fulra Limestone varied from 24 to 28°C (Saraswati et al, 1993) and was as high as 32°C in middle Eocene in Tanzania, located about the same latitudes (Pearson et al, 2001). The palynofloral assemblages and biomarker studies of lignite suggest angiosperm-dominated vegetation as the key organic source, with a hot and humid tropical climate (Dutta et al, 2011;Kar, 1985;Sharma & Saraswati, 2015).…”

“…These two regions are characterised by shallow marine carbonates formed during the Bartonian when a major transgression flooded several continental margin basins of India (Raju, 2008). These carbonates were dominantly made of larger benthic foraminifera that thrived in warm tropical seawaters estimated by the stable oxygen isotope analysis of the foraminiferal carbonates of Kutch to have a seawater temperature of 24-28°C (Saraswati, Ramesh, & Navada, 1993). Further, tropical angiosperm pollen assemblages and dinocysts suggestive of a warm and humid climate (Kar, 1985;Sharma & Saraswati, 2015) dominate in lignite occurring below the carbonates.…”

Barium anomaly preceding K/T boundary: possible causes and implications on end Cretaceous events of K/T sections in Cauvery basin (India), Israel, NE-Mexico and Guatemala

“…It has been established on several criteria that the warm global climate of the Mesozoic started deteriorating in Late Cretaceous time (Saraswati et al 1993). It is also established that this climatic change was not gradual but occurred in steplike transitions from one climatic state to the other (Berger et al 1981).…”

“…The close of the Mesozoic era marked the beginning of an eventful phase in geological history in terms of global climatic deterioration that left imprints on faunal and floral distributions and on the sedimentary deposits (Saraswati et al 1993). An abrupt boundary separates the Cretaceous from the Tertiary virtually everywhere in the global stratigraphic record (Meyers and Simoneit 1989).…”