Decline of soil respiration in northeastern Tibet through the transition into the Oligocene icehouse

Licht, Alexis; Dupont‐Nivet, Guillaume; Meijer, Niels; Rugenstein, Jeremy K. Caves; Schauer, Andrew J.; Fiebig, Jens; Mulch, Andreas; Hoorn, Carina; Barbolini, Natasha; Guo, Zhaojie

doi:10.1016/j.palaeo.2020.110016

Cited by 16 publications

(6 citation statements)

References 66 publications

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“…In any case, the two recognized environmental step changes concur with the global impact of the EOT-1 and Oi-1 events on terrestrial environments expressed via the hydrological cycle (e.g., Xiao et al, 2010;Page et al, 2019;Licht et al, 2020). Drying expressed by δ 15 N seems to occur through both steps but vegetation appears mostly affected by EOT-1.…”

Section: Environmental Changes Across the Eocene-oligocene Transitionsupporting

confidence: 52%

Age and driving mechanisms of the Eocene–Oligocene transition from astronomical tuning of a lacustrine record (Rennes Basin, France)

et al. 2021

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Abstract. The Eocene–Oligocene Transition (EOT) marks the onset of the Antarctic glaciation and the switch from greenhouse to icehouse climates. However, the driving mechanisms and the precise timing of the EOT remain controversial mostly due to the lack of well-dated stratigraphic records, especially in continental environments. Here we present a cyclo-magnetostratigraphic and sedimentological study of a ∼ 7.6 Myr long lacustrine record spanning the late Eocene to the earliest Oligocene, from a drill core in the Rennes Basin (France). Cyclostratigraphic analysis of natural gamma radiation (NGR) log data yields duration estimates of Chrons C12r through C16n.1n, providing additional constraints on the Eocene timescale. Correlations between the orbital eccentricity curve and the 405 kyr tuned NGR time series indicate that 33.71 and 34.10 Ma are the most likely proposed ages of the EO boundary. Additionally, the 405 kyr tuning calibrates the most pronounced NGR cyclicity to a period of ∼1 Myr, matching the g1–g5 eccentricity term, supporting its significant expression in continental depositional environments, and hypothesizing that the paleolake level may have behaved as a low-pass filter for orbital forcing. Two prominent changes in the sedimentary facies were detected across the EOT, which are temporally equivalent to the two main climatic steps, EOT-1 and Oi-1. We suggest that these two facies changes reflect the two major Antarctic cooling/glacial phases via the hydrological cycle, as significant shifts to drier and cooler climate conditions. Finally, the interval spanning the EOT precursor glacial event through EOT-1 is remarkably dominated by obliquity. This suggests preconditioning of the major Antarctic glaciation, either from obliquity directly affecting the formation/(in)stability of the incipient Antarctic Ice Sheet (AIS), or through obliquity modulation of the North Atlantic Deep Water production.

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Section: Environmental Changes Across the Eocene-oligocene Transitionsupporting

confidence: 52%

Age and driving mechanisms of the Eocene–Oligocene transition from astronomical tuning of a lacustrine record (Rennes Basin, France)

et al. 2021

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“…Decreased water stress on Burmese C3 plants during glacials could potentially account for 3–5 ‰ of depletion in the pedogenic carbonates of the wetter sites (Kohn, 2010), but fails to explain the much wider range of δ 13 C values. Seasonal variations in soil respiration rate and/or isotopic composition significantly impact soil CO 2 δ 13 C values (Breecker et al., 2009) and could potentially explain part of this difference, as already proposed for other past monsoonal C3 records (Licht et al., 2020). Low rates and high δ 13 C values of winter soil respiration followed by higher rates and lower δ 13 C values of early spring respiration could partly explain the observed difference between sites on both ends of the δ 13 C spectrum.…”

Section: Discussionmentioning

confidence: 81%

Dynamics of Pedogenic Carbonate Growth in the Tropical Domain of Myanmar

Licht

Kelson

Bergel

et al. 2022

Geochem Geophys Geosyst

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Pedogenic carbonate is widespread at mid latitudes where warm and dry conditions favor soil carbonate growth from spring to fall. The mechanisms and timing of pedogenic carbonate formation are more ambiguous in the tropical domain, where long periods of soil water saturation and high soil respiration enhance calcite dissolution. This paper provides stable carbon, oxygen and clumped isotope values from Quaternary and Miocene pedogenic carbonates in the tropical domain of Myanmar, in areas characterized by warm (>18°C) winters and annual rainfall up to 1,700 mm. We show that carbonate growth in Myanmar is delayed to the driest and coldest months of the year by sustained monsoonal rainfall from mid spring to late fall. The range of isotopic variability in Quaternary pedogenic carbonates can be solely explained by temporal changes of carbonate growth within the dry season, from winter to early spring. We propose that high soil moisture year‐round in the tropical domain narrows carbonate growth to the driest months and makes it particularly sensitive to the seasonal distribution of rainfall. This sensitivity is also enabled by high winter temperatures, allowing carbonate growth to occur outside the warmest months of the year. This high sensitivity is expected to be more prominent in the geological record during times with higher temperatures and greater expansion of the tropical realm. Clumped isotope temperatures, δ13C and δ18O values of tropical pedogenic carbonates are impacted by changes of both rainfall seasonality and surface temperatures; this sensitivity can potentially be used to track past tropical rainfall distribution.

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“…5.3; Abelson and Erez, 2017;Elsworth et al, 2017;Coxall et al, 2018) In any case, the two recognized environmental step changes concur with the global impact of the EOT-1 and Oi-1 events on terrestrial environments expressed via the hydrological cycle (e.g. Xiao et al, 2010;Page et al, 2019;Licht et al, 2020). Drying expressed by δ 15 N seems to occur through both steps but vegetation appears mostly affected by EOT-1.…”

Section: Environmental Changes Across the Eocene-oligocene Transitionmentioning

confidence: 75%

Age and driving mechanisms of the Eocene-Oligocene Transition from astronomical tuning of a lacustrine record (Rennes Basin, France)

Boulila

Dupont‐Nivet

Galbrun

et al. 2021

Preprint

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Abstract. The Eocene-Oligocene Transition (EOT) marks the onset of the Antarctic glaciation and the switch from greenhouse to icehouse climates. However, the driving mechanisms and the precise timing of the EOT remain controversial mostly due to the lack of well-dated stratigraphic records, especially in continental environments. Here we present a cyclo-magnetostratigraphic and sedimentological study of a ∼7.6 Myr-long lacustrine record spanning the late Eocene to the earliest Oligocene, from a drill-core in the Rennes Basin (France). Time-series analysis of natural gamma-ray (NGR) log data shows evidence of Milankovitch cycle bands. In particular, the 405 kyr stable eccentricity is expressed with strong amplitudes. Astronomical calibration to this 405 kyr periodicity yields duration estimates of Chrons C12r through C16n.1n, providing additional constraints on the middle–early Eocene timescale. Correlations between the orbital eccentricity curve and the 405 kyr tuned NGR time series and assumptions on their phase relationships, enable to test previously proposed ages for the EO boundary, indicating that 33.71 and 34.10 Ma are the most likely. Additionally, the 405 kyr tuning calibrates the most pronounced NGR cyclicity to a period of ∼1 Myr matching the g1-g5 eccentricity term. Such cyclicity has been recorded in other continental records, pointing to its significant expression in continental depositional environments. The record of g1-g5 and sometimes g2-g5 eccentricity terms in previously acquired sedimentary facies proxies in CDB1 core led us to hypothesize that the paleolake level may have behaved as a lowpass filter for orbital forcing. Two prominent changes in the sedimentary facies were detected across the EOT, which are temporally equivalent to the two main climatic steps, EOT-1 and Oi-1. Combined with previously acquired geochemical (δ15Norg, TOC), mineralogical (Quartz, clays) and pollen assemblage proxies from CDB1, we suggest that these two facies changes reflect the two major Antarctic cooling/glacial phases via the hydrological cycle, as significant shifts to drier and cooler climate conditions, thus supporting the stepwise nature of the EOT. Remarkably, a strongly dominant obliquity expressed in the latest Eocene corresponds in time to the interval from the EOT precursor glacial event till the EOT-1. We interpret the obliquity dominance as reflecting preconditioning phases for the onset of the major Antarctic glaciation, either from its direct impact on the formation/(in)stability of the incipient Antactic Ice Sheet (AIS), or through its modulation of the North Atlantic Deep Water production given the North Atlantic coastal location of the CDB1 site.

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Decline of soil respiration in northeastern Tibet through the transition into the Oligocene icehouse

Cited by 16 publications

References 66 publications

Age and driving mechanisms of the Eocene–Oligocene transition from astronomical tuning of a lacustrine record (Rennes Basin, France)

Age and driving mechanisms of the Eocene–Oligocene transition from astronomical tuning of a lacustrine record (Rennes Basin, France)

Dynamics of Pedogenic Carbonate Growth in the Tropical Domain of Myanmar

Age and driving mechanisms of the Eocene-Oligocene Transition from astronomical tuning of a lacustrine record (Rennes Basin, France)

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