Eocene–early Oligocene climate and vegetation change in southern China: Evidence from the Maoming Basin

Herman, Alexei B.; Spicer, Robert A.; Александрова, Г. Н.; Yang, Jian; Kodrul, Тatiana M.; Маслова, Н. П.; Spicer, Teresa E.V.; Chen, Gang; Jin, Jianhua

doi:10.1016/j.palaeo.2017.04.023

Cited by 76 publications

(54 citation statements)

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“…Our new chronological data show that the Lühe town section and, by extension, the Lühe Basin, record a modernization of vegetation that must have taken place before the earliest Oligocene. Although elsewhere in southern China there is evidence of some ecological change across the Eocene-Oligocene transition (e.g., Spicer et al, 2017), many first occurrences of typical Neogene and modern taxa appear in the middle to late Eocene, coincident with the development of monsoonal climates in that area (Spicer et al, 2014(Spicer et al, , 2017Herman et al, 2017). Until precise and accurate chronologies are developed for more basins across southern Asia, it is difficult to generalize about when and how the modernization of the biota occurred, other than it was a Paleogene phenomenon.…”

Section: Discussionmentioning

confidence: 99%

New U-Pb dates show a Paleogene origin for the modern Asian biodiversity hot spots

Linnemann

Kunzmann

et al. 2017

Geology

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Yunnan, in southwestern China, straddles two of the world's most important biodiversity hot spots (i.e., a biogeographic region that is both a reservoir of biodiversity and threatened with destruction) and hosts more than 200 fossiliferous sedimentary basins documenting the evolutionary history of that biodiversity, monsoon development, and regional elevation changes. The fossil biotas appear modern and have been assumed to be mostly Miocene in age. Dating has been by cross-correlation using palynology, magnetostratigraphy, and lithostratigraphy because numerical radiometric ages are lacking. Here we report the first unequivocal early Oligocene age (33-32 Ma) of a section in the Lühe Basin (25.141627°N, 101.373840°E, 1890 m above mean sea level), central Yunnan, based on U-Pb zircon dates of unreworked volcanic ash layers in a predominantly lacustrine succession hosting abundant plant and animal fossils. This section, located in Lühe town, is correlated with an adjacent section in the Lühe coal mine previously assigned to the upper Miocene based on regional lithostratigraphic comparison. Our substantially older age for the Lühe town section calls into question previous estimates for the surface uplift and climate history of the area, and the age of all other correlative basins. The modernization of the biota ~20 m.y. earlier than previously thought overturns existing concepts of vegetation history in southwestern China, and points to Paleogene modernization of the biota in Yunnan and associated Asian biodiversity hot spots.

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Section: Discussionmentioning

confidence: 99%

New U-Pb dates show a Paleogene origin for the modern Asian biodiversity hot spots

Linnemann

Kunzmann

et al. 2017

Geology

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“…Although several vegetation reconstructions are proposed in the literature for the Eocene, they were usually designed for higher CO 2 concentrations (e.g. 8 PAL, in Herold et al, 2014) and/or different palaeogeographies, such as the early Eocene (Sewall et al, 2000). Here, our Eocene fully coupled simulation uses an idealized vegetation map derived from the main modern climatic zones on the globe (see Fig.…”

Section: Late Eocene Fully Coupled Simulation Setupmentioning

confidence: 99%

The origin of Asian monsoons: a modelling perspective

et al. 2020

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Abstract. The Cenozoic inception and development of the Asian monsoons remain unclear and have generated much debate, as several hypotheses regarding circulation patterns at work in Asia during the Eocene have been proposed in the few last decades. These include (a) the existence of modern-like monsoons since the early Eocene; (b) that of a weak South Asian monsoon (SAM) and little to no East Asian monsoon (EAM); or (c) a prevalence of the Intertropical Convergence Zone (ITCZ) migrations, also referred to as Indonesian–Australian monsoon (I-AM). As SAM and EAM are supposed to have been triggered or enhanced primarily by Asian palaeogeographic changes, their possible inception in the very dynamic Eocene palaeogeographic context remains an open question, both in the modelling and field-based communities. We investigate here Eocene Asian climate conditions using the IPSL-CM5A2 (Sepulchre et al., 2019) earth system model and revised palaeogeographies. Our Eocene climate simulation yields atmospheric circulation patterns in Asia substantially different from modern conditions. A large high-pressure area is simulated over the Tethys ocean, which generates intense low tropospheric winds blowing southward along the western flank of the proto-Himalayan–Tibetan plateau (HTP) system. This low-level wind system blocks, to latitudes lower than 10∘ N, the migration of humid and warm air masses coming from the Indian Ocean. This strongly contrasts with the modern SAM, during which equatorial air masses reach a latitude of 20–25∘ N over India and southeastern China. Another specific feature of our Eocene simulation is the widespread subsidence taking place over northern India in the midtroposphere (around 5000 m), preventing deep convective updraught that would transport water vapour up to the condensation level. Both processes lead to the onset of a broad arid region located over northern India and over the HTP. More humid regions of high seasonality in precipitation encircle this arid area, due to the prevalence of the Intertropical Convergence Zone (ITCZ) migrations (or Indonesian–Australian monsoon, I-AM) rather than monsoons. Although the existence of this central arid region may partly result from the specifics of our simulation (model dependence and palaeogeographic uncertainties) and has yet to be confirmed by proxy records, most of the observational evidence for Eocene monsoons are located in the highly seasonal transition zone between the arid area and the more humid surroundings. We thus suggest that a zonal arid climate prevailed over Asia before the initiation of monsoons that most likely occurred following Eocene palaeogeographic changes. Our results also show that precipitation seasonality should be used with caution to infer the presence of a monsoonal circulation and that the collection of new data in this arid area is of paramount importance to allow the debate to move forward.

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“…In the Eocene southern China appears to have had only a weak monsoon presence compared to today ( Spicer et al., 2016 , Herman et al., 2017 ), but precipitation seasonality increased over time such that by the late early Oligocene an I-AM type monsoon climate was beginning to be established ( Herman et al., 2017 ). Today this part of China (specifically the Maoming Basin, Guangdong Province) ( Fig.…”

Section: Monsoons – What Are They?mentioning

confidence: 99%

Tibet, the Himalaya, Asian monsoons and biodiversity – In what ways are they related?

2017

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Prevailing dogma asserts that the uplift of Tibet, the onset of the Asian monsoon system and high biodiversity in southern Asia are linked, and that all occurred after 23 million years ago in the Neogene. Here, spanning the last 60 million years of Earth history, the geological, climatological and palaeontological evidence for this linkage is reviewed. The principal conclusions are that: 1) A proto-Tibetan highland existed well before the Neogene and that an Andean type topography with surface elevations of at least 4.5 km existed at the start of the Eocene, before final closure of the Tethys Ocean that separated India from Eurasia. 2) The Himalaya were formed not at the start of the India–Eurasia collision, but after much of Tibet had achieved its present elevation. The Himalaya built against a pre-existing proto-Tibetan highland and only projected above the average height of the plateau after approximately 15 Ma. 3) Monsoon climates have existed across southern Asia for the whole of the Cenozoic, and probably for a lot longer, but that they were of the kind generated by seasonal migrations of the Inter-tropical Convergence Zone. 4) The projection of the High Himalaya above the Tibetan Plateau at about 15 Ma coincides with the development of the modern South Asia Monsoon. 5) The East Asia monsoon became established in its present form about the same time as a consequence of topographic changes in northern Tibet and elsewhere in Asia, the loss of moisture sources in the Asian interior and the development of a strong winter Siberian high as global temperatures declined. 6) New radiometric dates of palaeontological finds point to southern Asia's high biodiversity originating in the Paleogene, not the Neogene.

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Eocene–early Oligocene climate and vegetation change in southern China: Evidence from the Maoming Basin

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Cited by 76 publications

References 28 publications

New U-Pb dates show a Paleogene origin for the modern Asian biodiversity hot spots

New U-Pb dates show a Paleogene origin for the modern Asian biodiversity hot spots

The origin of Asian monsoons: a modelling perspective

Tibet, the Himalaya, Asian monsoons and biodiversity – In what ways are they related?

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