Palaeovegetational reconstruction in Late Miocene: A case study based on early diagenetic carbonate cement from the Indian Siwalik

Carbon and oxygen isotope ratio of soil carbonate nodules and carbon isotope ratio of associated organic matter from the same nodules were also measured from the Mohand Rao section in a few cases (n = 9). From 9 to 8 Ma, the carbon isotope ratio of soil carbonates varies from − 10.8‰ to − 7.8‰ indicating dominance of C3 type vegetation in the flood plain. In contrast, from 5.4 to 4.8 Ma, the δ13C ranges from 0.1‰ to − 4.3‰ indicating that the vegetation consisted of mixed C3-C4 plants with C4 dominating the ecosystem. The carbon isotope ratio of the organic matter from the same soil carbonate nodules ranges from − 25.2‰ to − 24.4‰ (from 9 to 8 Ma) and − 17.4‰ to − 24.6‰ (from 5.4 to 4.8 Ma) corroborating the above results. The average δ18O value of soil carbonate nodules for the time period 9 to 8 Ma is − 8.8‰; for 5.4 to 4.8 Ma, the value is − 7.9‰. These average δ18O values are comparable with previously published oxygen isotope results of soil carbonates from Haripur Khol and Kangra valley.