Abstract:The Eocene is the initial stage of the Cenozoic global cooling. Compared with the abundant marine records, the continental records of Eocene are scarce. Throughout the Eocene, a series of continuous deposition of gypsum and volcanic tuff-bearing red clastic sediments have developed in the Nangqian Basin (NB). In this work, representative sediments were collected from the NB, and lipid biomarkers and compound-specific carbon isotopes of n-alkanes were analyzed. Based on the robust paleomagnetic age–depth model,… Show more
“…This would suggest a warm temperate climate rather than fully subtropical climate, with taxa that have frost sensitive leaves that are prone to winter deciduousness.Importantly, these four different methods for estimating palaeotemperatures match the present-day MAAT for this site, which ranges from 15-20°C depending on the exact elevation in this region with dynamic topography. The lack of temperature change from the Oligocene to today suggests that this location has been at its present-day elevation since at least the early Oligocene, supporting the hypothesis that local uplift had already taken place by this timeWei et al, 2022). This proposal has recently been grounded in supporting data byWu et al (2022) who likewise suggest that Lühe Basin town section had reached its present elevation by the early Oligocene.…”
supporting
confidence: 73%
“…This coupled atmosphere-ocean general circulation paleoclimate model includes paleo-rotations (latitude/longitude), changes in globally dynamic temperatures (e.g., SST changes from the South China Sea), and changes in cloud coverage and precipitation. In addition, there is supporting evidence from moist enthalpy from CLAMP and oxygen isotopes from carbonate nodules that topography of the eastern margin of Tibet was established immediately prior to and during the basin development (e.g., He et al, 2022).…”
Section: The Evolution Of the Tibetan Region And Eocene/oligocene Cli...mentioning
The Eocene-Oligocene transition (EOT; ~34 million years ago) marks a critical shift from a greenhouse to an icehouse climate. Whereas temperatures derived from marine records show a consensus ~ 4°C cooling worldwide, there is an emerging picture that the terrestrial realm experienced a heterogenous response to rapid climate change. Here, we reconstruct an 8-million-year terrestrial temperature record across the EOT at a tectonically unresolved location at the margins of the Tibetan Plateau, Lühe Basin (Yunnan, China). Our multi-proxy organic geochemistry approach, complemented by sedimentological interpretations, shows that Lühe Basin was a dynamic fluvial environment that maintained relatively stable average temperatures from ~ 35 − 27 million years ago. These palaeotemperatures match our model-based estimates, as well as palaeobotany-based estimates at a nearby site; these stable palaeotemperature trends differ from the global marine cooling, supporting a heterogenous response of terrestrial sections. Furthermore, these palaeotemperature estimates match present-day values at this location, suggesting that this area has not undergone significant temperature change – and possibly no significant uplift – since the late Paleogene.
“…This would suggest a warm temperate climate rather than fully subtropical climate, with taxa that have frost sensitive leaves that are prone to winter deciduousness.Importantly, these four different methods for estimating palaeotemperatures match the present-day MAAT for this site, which ranges from 15-20°C depending on the exact elevation in this region with dynamic topography. The lack of temperature change from the Oligocene to today suggests that this location has been at its present-day elevation since at least the early Oligocene, supporting the hypothesis that local uplift had already taken place by this timeWei et al, 2022). This proposal has recently been grounded in supporting data byWu et al (2022) who likewise suggest that Lühe Basin town section had reached its present elevation by the early Oligocene.…”
supporting
confidence: 73%
“…This coupled atmosphere-ocean general circulation paleoclimate model includes paleo-rotations (latitude/longitude), changes in globally dynamic temperatures (e.g., SST changes from the South China Sea), and changes in cloud coverage and precipitation. In addition, there is supporting evidence from moist enthalpy from CLAMP and oxygen isotopes from carbonate nodules that topography of the eastern margin of Tibet was established immediately prior to and during the basin development (e.g., He et al, 2022).…”
Section: The Evolution Of the Tibetan Region And Eocene/oligocene Cli...mentioning
The Eocene-Oligocene transition (EOT; ~34 million years ago) marks a critical shift from a greenhouse to an icehouse climate. Whereas temperatures derived from marine records show a consensus ~ 4°C cooling worldwide, there is an emerging picture that the terrestrial realm experienced a heterogenous response to rapid climate change. Here, we reconstruct an 8-million-year terrestrial temperature record across the EOT at a tectonically unresolved location at the margins of the Tibetan Plateau, Lühe Basin (Yunnan, China). Our multi-proxy organic geochemistry approach, complemented by sedimentological interpretations, shows that Lühe Basin was a dynamic fluvial environment that maintained relatively stable average temperatures from ~ 35 − 27 million years ago. These palaeotemperatures match our model-based estimates, as well as palaeobotany-based estimates at a nearby site; these stable palaeotemperature trends differ from the global marine cooling, supporting a heterogenous response of terrestrial sections. Furthermore, these palaeotemperature estimates match present-day values at this location, suggesting that this area has not undergone significant temperature change – and possibly no significant uplift – since the late Paleogene.
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