Application of ostracod-based carbonate clumped-isotope thermometry to paleo-elevation reconstruction in a hydrologically complex setting: A case study from the northern Tibetan Plateau

Abstract

Paleo-elevation estimates based on the oxygen and hydrogen isotopes of meteoric waters are commonly unreliable in hydrologically complex settings such as the northern Tibetan Plateau (TP), an area of confluence of the East Asian monsoon and mid-latitude Westerlies. Here, we explore a novel application of carbonate clumped-isotope thermometry for estimation of paleo-elevations based on a robust correlation of altitude with modern summer lake-surface temperatures that is independent of moisture sources and recycling processes. Using shallow-lake ostracod species, we estimate a summer lake-surface temperature of ∼ 20 ℃ for the Late Miocene Qaidam Basin of the northern TP. Paleo-elevation calculations yield basin floor estimates of ∼ 3475 m (for ∼ 11 Ma, based on a conventional geochronology model) or ∼ 3375 m (for ∼ 7.0 Ma, based on a revised geochronology model), each with an uncertainty of ±∼950 m, yielding elevations that are close to or slightly higher than the present-day elevation of the study site (∼3200 m). This study highlights the potential of ostracod-based carbonate clumped-isotope thermometry to reconstruct paleo- elevations in hydrologically complex areas of the TP and other montane systems.