Resetting Southern Tibet: The serious challenge of obtaining primary records of Paleoaltimetry

Quade, Jay; Leary, Ryan J.; Dettinger, Matthew; Orme, Devon A.; Krupa, Anthony; DeCelles, Peter G.; Kano, Akihiro; Katō, Hirokazu; Waldrip, R.; Huang, Wentao; Kapp, Paul

doi:10.1016/j.gloplacha.2020.103194

Cited by 40 publications

(23 citation statements)

References 102 publications

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“…To place our results within a regional chronological framework, we now compare them to the growing number of paleoelevation datasets based on various paleoelevation tools: mostly pedogenic carbonate stable isotopes (e.g., δ 18 O and Δ47), biomarkers [e.g., plant wax n -alkane stable isotopes δD and glycerol dialkyl glycerol tetraethers (GDGTs)], and fossils (e.g., floral and faunal assemblages, palynology, and leaf morphology). We rely on recent exhaustive data compilations that critically address these proxy limitations: Quade et al ( 40 ) for stable isotopes exploring tectonodiagenetic resetting, Spicer et al ( 25 ) for providing a full and critical assessment of fossil proxies, Kapp and Decelles ( 41 ) for integrating tectonic and geologic constraints, and Botsyun et al ( 39 ) for integrating paleoclimate configurations affecting the proxies.…”

Section: Discussionmentioning

confidence: 99%

Revised chronology of central Tibet uplift (Lunpola Basin)

et al. 2020

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Knowledge of the topographic evolution of the Tibetan Plateau is essential for understanding its construction and its influences on climate, environment, and biodiversity. Previous elevations estimated from stable isotope records from the Lunpola Basin in central Tibet, which indicate a high plateau since at least 35 Ma, are challenged by recent discoveries of low-elevation tropical fossils apparently deposited at 25.5 Ma. Here, we use magnetostratigraphic and radiochronologic dating to revise the chronology of elevation estimates from the Lunpola Basin. The updated ages reconcile previous results and indicate that the elevations of central Tibet were generally low (<2.3 km) at 39.5 Ma and high (3.5 to 4.5 km) at ~26 Ma. This supports the existence in the Eocene of low-elevation longitudinally oriented narrow regions until their uplift in the early Miocene, with potential implications for the growth mechanisms of the Tibetan Plateau, Asian atmospheric circulation, surface processes, and biotic evolution.

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Section: Discussionmentioning

confidence: 99%

Revised chronology of central Tibet uplift (Lunpola Basin)

et al. 2020

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“…It is important, however, that Quade et al. (2020) question whether paleosol carbonate routinely preserves pedogenic δ 18 O values. Because paleosol carbonate δ 18 O has been one of the main proxies for constraining the extent and height of the Tibetan and Andean plateaus, their topographic evolution may require revision.…”

Section: Terrestrial Climate Recordsmentioning

confidence: 99%

The Miocene: The Future of the Past

Steinthorsdottir

Coxall

Boer

et al. 2021

Paleoceanog and Paleoclimatol

191

153

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The Miocene epoch (23.03-5.33 Ma) was a time interval of global warmth, relative to today.Continental configurations and mountain topography transitioned toward modern conditions, and many flora and fauna evolved into the same taxa that exist today. Miocene climate was dynamic: long periods of early and late glaciation bracketed a ∼2 Myr greenhouse interval-the Miocene Climatic Optimum (MCO). Floras, faunas, ice sheets, precipitation, pCO 2 , and ocean and atmospheric circulation mostly (but not ubiquitously) covaried with these large changes in climate. With higher temperatures and moderately higher pCO 2 (∼400-600 ppm), the MCO has been suggested as a particularly appropriate analog for future climate scenarios, and for assessing the predictive accuracy of numerical climate models-the same models that are used to simulate future climate. Yet, Miocene conditions have proved difficult to reconcile with models. This implies either missing positive feedbacks in the models, a lack of knowledge of past climate forcings, or the need for re-interpretation of proxies, which might mitigate the model-data discrepancy. Our understanding of Miocene climatic, biogeochemical, and oceanic changes on broad spatial and temporal scales is still developing. New records documenting the physical, chemical, and biotic aspects of the Earth system are emerging, and together provide a more comprehensive understanding of this important time interval. Here, we review the state-of-the-art in Miocene climate, ocean circulation, biogeochemical cycling, ice sheet dynamics, and biotic adaptation research as inferred through proxy observations and modeling studies. Plain Language Summary During the Miocene time period (∼23-5 million years ago),Planet Earth looked similar to today, with some important differences: the climate was generally warmer and highly variable, while atmospheric CO 2 was not much higher. Continental-sized ice sheets were only present on Antarctica, but not in the northern hemisphere. The continents drifted to near their modernday positions, and plants and animals evolved into the many (near) modern species. Scientists study the Miocene because present-day and projected future CO 2 levels are in the same range as those reconstructed for the Miocene. Therefore, if we can understand climate changes and their biotic responses from the Miocene past, we are able to better predict current and future global changes. By comparing Miocene climate reconstructions from fossil and chemical data to climate simulations produced by computer models, scientists are able to test their understanding of the Earth system under higher CO 2 and warmer conditions than those of today. This helps in constraining future warming scenarios for the coming STEINTHORSDOTTIR ET AL.

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“…is cut through by Miocene dykes, so making unlikely a Miocene age for the Liuqu as is sometimes accepted (e.g. Leary et al., 2016 , 2017 ; Quade et al, 2020 ).…”

Section: An Overview Of the Cenozoic Biota Of The Tibetan Regionmentioning

confidence: 99%

Cenozoic topography, monsoons and biodiversity conservation within the Tibetan Region: An evolving story

Spicer

Farnsworth

2020

Plant Diversity

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The biodiversity of the Himalaya, Hengduan Mountains and Tibet, here collectively termed the Tibetan Region, is exceptional in a global context. To contextualize and understand the origins of this biotic richness, and its conservation value, we examine recent fossil finds and review progress in understanding the orogeny of the Tibetan Region. We examine the deep-time origins of monsoons affecting Asia, climate variation over different timescales, and the establishment of environmental niche heterogeneity linked to topographic development. The origins of the modern biodiversity were established in the Eocene, concurrent with the formation of pronounced topographic relief across the Tibetan Region. High (>4 km) mountains to the north and south of what is now the Tibetan Plateau bounded a Paleogene central lowland (<2.5 km) hosting moist subtropical vegetation influenced by an intensifying monsoon. In mid Miocene times, before the Himalaya reached their current elevation, sediment infilling and compressional tectonics raised the floor of the central valley to above 3000 m, but central Tibet was still moist enough, and low enough, to host a warm temperate angiosperm-dominated woodland. After 15 Ma, global cooling, the further rise of central Tibet, and the rain shadow cast by the growing Himalaya, progressively led to more open, herb-rich vegetation as the modern high plateau formed with its cool, dry climate. In the moist monsoonal Hengduan Mountains, high and spatially extensive since the Eocene but subsequently deeply dissected by river incision, Neogene cooling depressed the tree line, compressed altitudinal zonation, and created strong environmental heterogeneity. This served as a cradle for the then newly-evolving alpine biota and favoured diversity within more thermophilic vegetation at lower elevations. This diversity has survived through a combination of minimal Quaternary glaciation, and complex relief-related environmental niche heterogeneity. The great antiquity and diversity of the Tibetan Region biota argues for its conservation, and the importance of that biota is demonstrated through our insights into its long temporal gestation provided by fossil archives and information written in surviving genomes. These data sources are worthy of conservation in their own right, but for the living biotic inventory we need to ask what it is we want to conserve. Is it 1) individual taxa for their intrinsic properties, 2) their services in functioning ecosystems, or 3) their capacity to generate future new biodiversity? If 2 or 3 are our goal then landscape conservation at scale is required, and not just seed banks or botanical/zoological gardens.

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Resetting Southern Tibet: The serious challenge of obtaining primary records of Paleoaltimetry

Cited by 40 publications

References 102 publications

Revised chronology of central Tibet uplift (Lunpola Basin)

Revised chronology of central Tibet uplift (Lunpola Basin)

The Miocene: The Future of the Past

Cenozoic topography, monsoons and biodiversity conservation within the Tibetan Region: An evolving story

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