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Effects of global warming and Tibetan Plateau uplift on East Asian climate during the mid-Cretaceous
Abstract
Sedimentary records indicate that subtropical and mid-latitude East Asia exhibited considerable drying and wetting, respectively, during the mid-Cretaceous, which is considered to be relevant to much higher atmospheric carbon dioxide (pCO 2) concentrations and/or proto-Tibetan Plateau (proto-TP) uplift. In order to explore and compare their roles on the East Asian climate evolution, we conducted simulations of the mid-Cretaceous climate system with different atmospheric pCO 2 levels and varying topographies. The results show that both factors had significant influences on the East Asian climate. As the increase in atmospheric pCO 2 levels from ~560-1120 ppmv to ~1120-2240 ppmv, the precipitation increases considerably over mid-latitude East Asia, but only small changes in the subtropical portion of East Asia occur. Simultaneously, the effects of the proto-TP uplift are opposite to those of global warming trend during that period. Generally, it leads to a precipitation decrease over subtropical East Asia, but rather minor changes over mid-latitude East Asia. These changes are qualitatively consistent with the deduction based on the geological records, but the magnitudes of the modeled precipitation changes are relatively smaller. Therefore, we can conclude that the subtropical East Asian drying during the mid-Cretaceous can be partly explained by the proto-TP uplift, while the mid-latitude East Asian wetting was partly due to global warming. However, additional factor(s) also played a significant role in the East Asian climate evolution during the mid-Cretaceous.
... Given the lack of quantitative paleoclimate data in the Late Cretaceous, comparisons between climate simulations and proxies are often constrained to qualitative analyses (Higuchi et al., 2021;J. Zhang et al., 2021J. Zhang et al., , 2024. For this study, we employ the climate-sensitive sedimentary records compiled by Xu et al. (2021) for East Asia (Figure 1a), which provide a robust framework for assessing paleoenvironmental conditions. According to their work, the relationships between climate states and sediment types are categorized as follows: ...
... Aridity, commonly used to study Cretaceous climate (Higuchi et al., 2021;J. Zhang et al., 2021J. Zhang et al., , 2024, shows a more sensitive response to mountain configurations (Table 1). Exp_cst significantly improves aridity accuracy compared to Exp_ctl (Table 1), highlighting the role of Coastal Mountains in East Asia. Exp_cst_ty exhibits the highest accuracy (Table 1) because it extends the arid belt eastward from Exp_ctl (Figure 2f), better align ...
Plain Language Summary
Topography plays a pivotal role in climate systems, particularly in East Asia, where diverse mountain ranges significantly influence regional climate dynamics. The Late Cretaceous period was characterized by a complex topography, including Coastal, Taihang, and Yanshan Mountains, which contributed to distinct climatic regimes. However, the specific climatic impacts of these inland mountain ranges and their interactions with adjacent coastal features remain inadequately characterized. This study aims to bridge this knowledge gap by employing paleoclimate modeling to assess the effects of these mountain configurations on temperature and precipitation patterns. We use two model‐proxy comparison strategies, revealing that the combination of Coastal, Taihang, and Yanshan Mountains had slightly higher accuracy than other configurations. Combined with geological evidence, we propose this mountain configuration for East Asia during the Late Cretaceous. Our results indicate that the joint influence of coastal and inland mountain ranges significantly modifies temperature and precipitation, impacting clouds, atmospheric circulation processes, and monsoon systems. These findings underscore the necessity of integrating topographical influences in paleoclimate simulations, refining our understanding of the intricate interactions between ancient landscapes and climate systems.
... Recently, the emission of atmospheric pollutants has been effectively controlled, and the chemical properties of precipitation have undergone varying degrees of change in the context of China's Ecological Civilization Construction Ren et al., 2024;Sun et al., 2024). Moreover, global climate warming may potentially impact precipitation patterns and monsoons in inland China (He et al., 2023;Liu et al., 2023;Zhang et al., 2024). These factors further complicate the mechanisms by which anthropogenic emissions and terrestrial and marine sources affect the chemical composition of precipitation in northwest China. ...
The Tibetan Plateau was formed by long-term terrane accretion and block collision, controlled by complicated Mesozoic-Cenozoic geodynamic mechanisms. However, its detail Cretaceous evolution history remains controversial. This study compiles available low-temperature thermochronology results and adakitic rocks data from the Qiangtang and Lhasa terranes to investigate its evolution. Two collected datasets synthetically demonstrate a
deep-surface coupling relationship with rapid exhumation and crustal thickening during ~120–80 Ma over the Qiangtang and Lhasa terranes. These terranes amalgamated before 120 Ma, resulting in rapid uplift and crustal thickening of southern Qiangtang during 120–80 Ma. Meanwhile, other sub-terranes outside of the southern Qiangtang terrane, including northern Qiangtang, northern Lhasa, and central Lhasa, also underwent stepwise surface uplift due to intense folding and thrusting. Instead of continuous crustal thickening, the northern and
central Lhasa sub-terranes experienced intense erosion and delamination of early thickened crust during ~90–80 Ma. Furthermore, the southern Lhasa sub-terrane rapidly uplifted during 70–60 Ma due to the Neo-Tethyan subduction. Eventually, the Cretaceous high geomorphic configuration across the Qiangtang and Lhasa terranes was shaped by terrane collision, lower crustal delamination, and Neo-Tethyan subduction prior to the India-Asia continental collision.
Geologic evidence and palaeoclimate simulations have indicated the existence of an extensive, interconnected megamonsoon system over the Pangaea supercontinent. However, the ways in which subsequent continental break-up about 180 million years ago and reassembly in the Cenozoic, as well as large global climatic fluctuations, influenced the transition to the modern global monsoon system are uncertain. Here we use a large set of simulations of global climate every 10 million years over the past 250 million years to show that the monsoon system evolved in three stages due to changes in palaeogeography: a spatially extensive land monsoon with weak precipitation in the Triassic period (>170 Ma), a smaller land monsoon with intense precipitation in the Cretaceous period (170–70 Ma) and a return to a broader, weaker monsoon in the Cenozoic era (<70 Ma). It is found that global-mean temperature variations have little impact on global land-monsoon area and intensity over tectonic timescales. Applying an analysis of atmospheric energetics, we show that these variations of the global land monsoon are governed by continental area, latitudinal location and fragmentation.
The Pangea era is an exceptional phase in Earth's history. It is characterized by its hothouse climate state and the latest supercontinent. Thus, it is expected that atmospheric circulation in the Pangea era was largely different from that of the modern world. Here, we study the Hadley circulation in the Pangea era and compare it with that of the present, by performing climate simulations. Our results show that the annual mean Hadley cells are about 20% and 45% weaker than that in the pre-industrial (PI) climate, and their poleward edges are about 2° wider in latitude. The austral winter cell is weakened by 27% and expanded by 2.6°, while the changes of the boreal winter cell are not significant. One distinctive feature is that the ascending branches of the boreal and austral winter cells shift to 23°S and 18°N, respectively, which are much more poleward than their present locations. Our analyses demonstrate that the weakening and widening of the Hadley circulation is due to increasing tropical and subtropical static stability, and that the poleward shifts of the ascending branches of the winter cells are associated with the geographic configuration of the supercontinent Pangea.
We simulate climate variations in the past 250 million years (Myr), using the fully coupled Community Earth System Model version 1.2.2 (CESM1.2.2) with the Community Atmosphere Model version 4 (CAM4). Three groups of simulations are performed, each including 26 simulations, with a 10‐million‐year interval. The Control group is constrained by paleogeography, increasing solar radiation, and reconstructed global mean surface temperatures (GMSTs) by tuning CO2 concentrations. No ice sheets are prescribed for all simulations except for the pre‐industrial (PI) simulation in which modern geography, ice sheets and vegetation are used. Simulated zonal mean surface temperatures are always higher than those of proxy reconstructions in the tropics, but lower than those of proxy reconstructions at middle latitudes. The relative importance of individual contributing factors for surface temperature variations in the past 250 Myr is diagnosed, using the energy‐balance analysis. Results show that greenhouse gases are the major driver in regulating GMST variations, with a maximum contribution of 12.2°C. Varying surface albedo contributes to GMST variations by 3.3°C. Increasing solar radiation leads to GMST increases by 1.5°C. Cloud radiative effects have relatively weak impacts on GMST variations, less than ±0.8°C. For comparison, two groups of sensitivity simulations are performed. One group has the CO2 concentration fixed at 10 times the PI value, and the other group has fixed CO2 concentration of 10 times the PI value and fixed solar radiation at the present‐day value, showing that varying both paleogeography and solar constant and varying paleogeography alone result in GMST changes by 7.3°C and 5.6°C, respectively.
Earth’s climate during the last 4.6 billion years has changed repeatedly between cold (icehouse) and warm (greenhouse) conditions. The hottest conditions (supergreenhouse) are widely assumed to have lacked an active cryosphere. Here we show that during the archetypal supergreenhouse Cretaceous Earth, an active cryosphere with permafrost existed in Chinese plateau deserts (astrochonological age ca. 132.49–132.17 Ma), and that a modern analogue for these plateau cryospheric conditions is the aeolian–permafrost system we report from the Qiongkuai Lebashi Lake area, Xinjiang Uygur Autonomous Region, China. Significantly, Cretaceous plateau permafrost was coeval with largely marine cryospheric indicators in the Arctic and Australia, indicating a strong coupling of the ocean–atmosphere system. The Cretaceous permafrost contained a rich microbiome at subtropical palaeolatitude and 3–4 km palaeoaltitude, analogous to recent permafrost in the western Himalayas. A mindset of persistent ice-free greenhouse conditions during the Cretaceous has stifled consideration of permafrost thaw as a contributor of C and nutrients to the palaeo-oceans and palaeo-atmosphere.
Paleotemperature proxy data form the cornerstone of paleoclimate research and are integral to understanding the evolution of the Earth system across the Phanerozoic Eon. Here, we present PhanSST, a database containing over 150,000 data points from five proxy systems that can be used to estimate past sea surface temperature. The geochemical data have a near-global spatial distribution and temporally span most of the Phanerozoic. Each proxy value is associated with consistent and queryable metadata fields, including information about the location, age, and taxonomy of the organism from which the data derive. To promote transparency and reproducibility, we include all available published data, regardless of interpreted preservation state or vital effects. However, we also provide expert-assigned diagenetic assessments, ecological and environmental flags, and other proxy-specific fields, which facilitate informed and responsible reuse of the database. The data are quality control checked and the foraminiferal taxonomy has been updated. PhanSST will serve as a valuable resource to the paleoclimate community and has myriad applications, including evolutionary, geochemical, diagenetic, and proxy calibration studies.
The apex of Earth's penultimate icehouse during the Permo‐Carboniferous coincided with dramatic glacial‐interglacial fluctuations in atmospheric CO2, sea level, and high‐latitude ice. Global transformations in marine fauna also occurred during this interval, including a rise to peak foraminiferal diversity, suggesting that glacial‐interglacial climate change impacted marine ecosystems. Nevertheless, changes in ocean circulation and temperature over the Permo‐Carboniferous and their influence on marine ecosystem change are largely unknown. Here, we present simulations of glacial and interglacial phases of the latest Carboniferous‐early Permian (∼305‐295 Ma) using the Community Earth System Model version 1.2 to provide estimates of global ocean circulation and temperature during this interval. We characterize general patterns of glacial and interglacial surface ocean currents, temperature, and salinity, and compare them to the documented abundance and distribution of Permo‐Carboniferous marine fauna as well as a preindustrial climate simulation. We then explore how glacial‐interglacial changes in atmospheric CO2, sea level, and high‐latitude ice extent impact thermohaline circulation. We find that glacial‐interglacial changes in equatorial surface temperatures are consistently ∼3–6°C. Ocean circulation is stronger overall in the glacial simulation, particularly as lower atmospheric CO2 enables deep convection in the Northern Hemisphere. Wind‐driven circulation, heat transport, and upwelling intensity are stronger overall in the Permo‐Carboniferous superocean relative to the preindustrial oceans at the same level of atmospheric CO2. We also find that CO2‐induced glacial conditions of the early Permian may have promoted foraminiferal diversity through increased thermal gradients and suppressed riverine input in marine shelf environments.
The widening of the South Atlantic Basin led to the reorganization of regional atmospheric and oceanic circulations. However, the response of the Atlantic Intertropical Convergence Zone (ITCZ), and South American and African monsoons across paleoclimate states, especially under constant paleogeographic and climatic changes, has not been well understood. Here we report on paleoclimate simulations of the Cenomanian (∼95 Ma), early Eocene (∼55 Ma), and middle Miocene (∼14 Ma) using the Community Earth System Model version 1.2 to understand how the migration of the South American and African continents to their modern‐day positions, uplift of the Andes and East African Rift Zone, and the decline of atmospheric CO2 changed the Atlantic ITCZ, and the South American and African monsoons and rainforests. Our work demonstrates that the South Atlantic widening developed the Atlantic ITCZ. The South Atlantic widening and Andean orogeny led to a stronger South American monsoon. We find the orogeny of the East African Rift Zone is the primary mechanism that strengthened the East African monsoon, whereas the West African monsoon became weaker through time as West Africa migrated toward the subtropics and CO2 levels fell below 500 ppm. We utilize the Köppen‐Geiger Climate Classification as an indicator for maximum rainforest extent. We find that during the Cenomanian and early Eocene, a Pan‐African rainforest existed, while the Amazon rainforest was restricted toward the northwestern corner of South America. During the middle Miocene, the Pan‐African rainforest was reduced to near its modern‐day size, while the Amazon rainforest expanded eastward.
Uplift of the Gangdese Mountains is important to the evolution of Asian monsoons and the formation of Tibetan Plateau, but its paleoaltitude before the India-Asia collision (Late Cretaceous) is less constrained so far. In this study, we investigate whether the geological records, which are indicators of soil dryness, discovered in East Asia can provide such a constraint. Through climate modeling using the Community Earth System Model version 1.2.2, it is found that the extent of dry land in East Asia is sensitive to the altitude of the Gangdese Mountains. It expands eastwards and southwards with the rise of the mountain range. Comparison of the model results with all the available geological records in this region suggests that the Gangdese Mountains had attained a height of ∼2 km in the Late Cretaceous.
High-resolution general circulation models (GCMs) can provide new insights into the simulated distribution of global precipitation. We evaluate how summer precipitation is represented over Asia in global simulations with a grid length of 14 km. Three simulations were performed: one with a convection parametrization, one with convection represented explicitly by the model's dynamics, and a hybrid simulation with only shallow and mid-level convection parametrized. We evaluate the mean simulated precipitation and the diurnal cycle of the amount, frequency, and intensity of the precipitation against satellite observations of precipitation from the Climate Prediction Center morphing method (CMORPH). We also compare the high-resolution simulations with coarser simulations that use parametrized convection.
The simulated and observed precipitation is averaged over spatial scales defined by the hydrological catchment basins; these provide a natural spatial scale for performing decision-relevant analysis that is tied to the underlying regional physical geography. By selecting basins of different sizes, we evaluate the simulations as a function of the spatial scale. A new BAsin-Scale Model Assessment ToolkIt (BASMATI) is described, which facilitates this analysis.
We find that there are strong wet biases (locally up to 72 mm d-1 at small spatial scales) in the mean precipitation over mountainous regions such as the Himalayas. The explicit convection simulation worsens existing wet and dry biases compared to the parametrized convection simulation. When the analysis is performed at different basin scales, the precipitation bias decreases as the spatial scales increase for all the simulations; the lowest-resolution simulation has the smallest root mean squared error compared to CMORPH.
In the simulations, a positive mean precipitation bias over China is primarily found to be due to too frequent precipitation for the parametrized convection simulation and too intense precipitation for the explicit convection simulation. The simulated diurnal cycle of precipitation is strongly affected by the representation of convection: parametrized convection produces a peak in precipitation too close to midday over land, whereas explicit convection produces a peak that is closer to the late afternoon peak seen in observations. At increasing spatial scale, the representation of the diurnal cycle in the explicit and hybrid convection simulations improves when compared to CMORPH; this is not true for any of the parametrized simulations.
Some of the strengths and weaknesses of simulated precipitation in a high-resolution GCM are found: the diurnal cycle is improved at all spatial scales with convection parametrization disabled, the interaction of the flow with orography exacerbates existing biases for mean precipitation in the high-resolution simulations, and parametrized simulations produce similar diurnal cycles regardless of their resolution. The need for tuning the high-resolution simulations is made clear. Our approach for evaluating simulated precipitation across a range of scales is widely applicable to other GCMs.
The East Asian coastal mountains have been in place during the Late Cretaceous times, thus substantially influencing the Asian climate. So far, their altitude is uncertain. Here we investigate the influence of such mountains on Asian climate using an atmosphere‐ocean general circulation model, Community Earth System Model version 1.2.2. Simulation results show that extensive deserts would develop over the eastern part of the East Asia if the altitude of the coastal mountains was greater than 2 km. This is due to the pumping effect of the coastal mountains which deprives the moisture from the East Asian interior during summer and autumn, leading to less precipitation and greater potential evapotranspiration. The existence of extensive desert areas would be more consistent with the presented Asian paleoenvironmental reconstructions. Therefore, our results independently indicate that the altitude of the coastal mountains had attained 2 km or more by the early Late Cretaceous.
Plain Language Summary
Projections indicate future global warming and an increase in the annual and summer mean precipitations and humidity around East Asia. On the other hand, geological records have shown the low‐latitude regions of East Asia during the warmer mid‐Cretaceous shifted toward more arid conditions, relative to the cooler early and late Cretaceous. We simulate the Present‐day and Cretaceous climates with different CO2 levels using a climate model, to investigate and compare the water cycle responses to global warming in the two periods. With increased atmospheric CO2, the precipitation in the low latitude regions of East Asia decreases in the Cretaceous experiment, consistent with changes in the water cycle during the mid‐Cretaceous as indicated by geological data, while it increases in the Present‐day experiment. It is found that this difference is caused by the different summer atmospheric circulation response due to the absence of the Tibetan Plateau in the Cretaceous. In conclusion, this study highlights that the regional changes in the hydrological cycle due to climate warming are strongly dependent on background geographical conditions.
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.
Plain Language Summary
Paleo‐elevation is an important factor in understanding the mountain building processes. Strong correlations are observed between crustal thickness, elevation, and Sr/Y and (La/Yb)N of magmatic rocks for both subduction‐related and collision‐related mountain belts. We established empirical equations derived from modern examples and applied them to constrain the paleo‐elevation evolution of the Tibetan Plateau since the Cretaceous. Our calculated results are broadly consistent with previous estimates based on stable isotope and structural analyses and document a complex uplift history. In central Tibet, a proto‐plateau with an elevation >3,000 m was formed during the Late Cretaceous and was higher than the Gangdese continental arc in the south. This protoplateau collapsed at the same time as the southern Tibet plateau (Lhasaplano) was uplifted prior to the India‐Asia collision formed before the India‐Asia collision. During the India‐Asia collision in the Cenozoic, northern and southern Tibet were uplift first, followed by uplift of central Tibet. A paleovalley was formed in central Tibet during the Paleogene and elevations of the whole Tibetan Plateau similar to the present‐day were achieved during the Miocene.
The precollisional locations and geometries of the Lhasa terrane (LT) are critical to constrain the India‐Asia collision. However, the inclinations of the Cretaceous paleomagnetic data obtained from the northern limb of folds are obviously lower than those obtained from the southern limb, which cause large discrepant paleolatitudes of the LT prior to India‐Asia collision. Here, we carried out a new paleomagnetic investigation on the Late Cretaceous Jingzhushan Formation red beds in the far western LT. The tilt‐corrected site mean direction yielded a palaeopole at 74.4°N, 226.0°E with A95 = 3.8° (N = 54). This paleomagnetic data set passes fold tests and indicates that the studied area was located at 19.6° ± 3.8°N during the Late Cretaceous. However, the mean inclination calculated from the northern limb of folds (Is = 19.0°) is significantly lower than that of the southern limb of folds (Is = 51.8°). This inclination discrepancy of the Jingzhushan Formation red beds may be attributed to the syntectonic sedimentation. Nevertheless, the site mean direction obtained from both limbs of folds is generally consistent with the site mean direction after syntectonic‐sedimentation correction. Our new paleomagnetic results, combined with the reliable Cretaceous paleomagnetic results from the LT showed that the southern margin of Asia had a present‐day relatively east‐west alignment prior to India‐Asia collision.
The mid-Cretaceous period was one of the warmest intervals of the past 140 million years1–5, driven by atmospheric carbon dioxide levels of around 1,000 parts per million by volume6. In the near absence of proximal geological records from south of the Antarctic Circle, it is disputed whether polar ice could exist under such environmental conditions. Here we use a sedimentary sequence recovered from the West Antarctic shelf—the southernmost Cretaceous record reported so far—and show that a temperate lowland rainforest environment existed at a palaeolatitude of about 82° S during the Turonian–Santonian age (92 to 83 million years ago). This record contains an intact 3-metre-long network of in situ fossil roots embedded in a mudstone matrix containing diverse pollen and spores. A climate model simulation shows that the reconstructed temperate climate at this high latitude requires a combination of both atmospheric carbon dioxide concentrations of 1,120–1,680 parts per million by volume and a vegetated land surface without major Antarctic glaciation, highlighting the important cooling effect exerted by ice albedo under high levels of atmospheric carbon dioxide. Multi-proxy core data and model simulations support the presence of temperate rainforests near the South Pole during mid-Cretaceous warmth, indicating very high CO2 levels and the absence of Antarctic ice.
The East Asian monsoon plays an integral role in human society, yet its geological history and controlling processes are poorly understood. Using a general circulation model and geological data, we explore the drivers controlling the evolution of the monsoon system over the past 150 million years. In contrast to previous work, we find that the monsoon is controlled primarily by changes in paleogeography, with little influence from atmospheric CO 2 . We associate increased precipitation since the Late Cretaceous with the gradual uplift of the Himalayan-Tibetan region, transitioning from an ITCZ-dominated monsoon to a sea breeze–dominated monsoon. The rising region acted as a mechanical barrier to cold and dry continental air advecting into the region, leading to increasing influence of moist air from the Indian Ocean/South China Sea. We show that, apart from a dry period in the middle Cretaceous, a monsoon system has existed in East Asia since at least the Early Cretaceous.
The Early Eocene, a period of elevated atmospheric CO 2 (>1000 ppmv), is considered an analog for future climate. Previous modeling attempts have been unable to reproduce major features of Eocene climate indicated by proxy data without substantial modification to the model physics. Here, we present simulations using a state-of-the-art climate model forced by proxy-estimated CO 2 levels that capture the extreme surface warmth and reduced latitudinal temperature gradient of the Early Eocene and the warming of the Paleocene-Eocene Thermal Maximum. Our simulations exhibit increasing equilibrium climate sensitivity with warming and suggest an Eocene sensitivity of more than 6.6°C, much greater than the present-day value (4.2°C). This higher climate sensitivity is mainly attributable to the shortwave cloud feedback, which is linked primarily to cloud microphysical processes. Our findings highlight the role of small-scale cloud processes in determining large-scale climate changes and suggest a potential increase in climate sensitivity with future warming.
Plain Language Summary
The evolution of the Asian monsoons and aridification of Asia's interior are thought to be driven by Tibetan‐Himalayan uplift. Recent geological observations suggest that the uplifted proto‐Tibetan Plateau (proto‐TP) migrated northward in the subtropics since the early Eocene and reached its present position by the latest Oligocene. We therefore simulated the effects of this process on East‐Central Asian climate. Our climate modeling shows the northward migration of the high proto‐TP from 21–29°N to 29–37°N can significantly change the present‐day wind and precipitation patterns over East‐Central Asia. Especially, Central Asia become drier because of the displacement of the anomalous dry belt caused by large‐scale atmospheric subsidence. We further suggest that forcing by the paleolatitudinal migration of the high proto‐TP within the subtropics from the Eocene to the earliest Miocene could have driven the Central Asian paleoclimate to drier conditions, but migration might not be the sole parameter that governed the East Asian monsoon during the Paleogene.
The Himalayan-Tibetan orogen culminated during the Cenozoic India – Asia collision, but its geological framework and initial growth were fundamentally the result of multiple, previous ocean closure and intercontinental suturing events. As such, the Himalayan-Tibetan orogen provides an ideal laboratory to investigate geological signatures of the suturing process in general, and how the Earth’s highest and largest orogenic feature formed in specific. This paper synthesizes the Triassic through Cenozoic geology of the central Himalayan-Tibetan orogen and presents our tectonic interpretations in a time series of schematic lithosphere-scale cross-sections and paleogeographic maps. We suggest that north-dipping subducting slabs beneath Asian continental terranes associated with closure of the Paleo-, Meso-, and Neo-Tethys oceans experienced phases of southward trench retreat prior to intercontinental suturing. These trench retreat events created ophiolites in forearc extensional settings and/or a backarc oceanic basins between rifted segments of upper-plate continental margin arcs. This process may have occurred at least three times along the southern Asian margin during northward subduction of Neo-Tethys oceanic lithosphere: from ~174 to 156 Ma; 132 to 120 Ma; and 90 to 70 Ma. At most other times, the Tibetan terranes underwent Cordilleran-style or collisional contractional deformation. Geological records indicate that most of northern and central Tibet (the Hoh-Xil and Qiangtang terranes, respectively) were uplifted above sea level by Jurassic time, and southern Tibet (the Lhasa terrane) north of its forearc region has been above sea level since ~100 Ma. Stratigraphic evidence indicates that the northern Himalayan margin of India collided with an Asian-affinity subduction complex – forearc – arc system beginning at ~60 Ma. Both the Himalaya (composed of Indian crust) and Tibet show continuous geological records of orogenesis since ~60 Ma. As no evidence exists in the rock record for a younger suture, the simplest interpretation of the geology is that India – Asia collision initiated at ~60 Ma. Plate circuit, paleomagnetic, and structural reconstructions, however, suggest that the southern margin of Asia was too far north of India to have collided with it at that time. Seismic tomographic images are also suggestive of a second, more southerly Neo-Tethyan oceanic slab in the lower mantle where the northernmost margin of India may have been located at ~60 Ma. The geology of Tibet and the India – Asia suture zone permits an alternative collision scenario in which the continental margin arc along southern Asia (the Gangdese arc) was split by extension beginning at ~90 Ma, and along with its forearc to the south (the Xigaze forearc), rifted southward and opened a backarc ocean basin. The rifted arc collided with India at ~60 Ma whereas the hypothetical backarc ocean basin may not have been consumed until ~45 Ma. A compilation of igneous age data from Tibet shows that the most recent phase of Gangdese arc magmatism in the southern Lhasa terrane initiated at ~70 Ma, peaked at ~51 Ma, and terminated at ~38 Ma. Cenozoic potassic-adakitic magmatism initiated at ~45 Ma within a ~200-km-wide elliptical area within the northern Qiangtang terrane, after which it swept westward and southward with time across central Tibet until ~26 Ma. At 26-23 Ma, potassic-adakitic magmatism swept southward across the Lhasa terrane, a narrow (~20 km width), orogen-parallel basin developed at low elevation along the axis of the India – Asia suture zone (the Kailas basin), and Greater Himalayan Sequence rocks began extruding southward between the South Tibetan Detachment and Main Central Thrust. The Kailas basin was then uplifted to >4 km elevation by ~20 Ma, after which parts of the India – Asia suture zone and Gangdese arc experienced >6 km of exhumation (between ~20 and 16 Ma). Between ~16 and 12 Ma, slip along the South Tibetan Detachment terminated and east-west extension initiated in the northern Himalaya and Tibet. Potassic-adakitic magmatism in the Lhasa terrane shows a northward younging trend in the age of its termination, beginning at 20-18 Ma until volcanism ended at 8 Ma. We interpret the post-45 Ma geological evolution in the context of the subduction dynamics of Indian continental lithosphere and its interplay with delamination of Asian mantle lithosphere.
Constraining the growth of the Tibetan Plateau in time and space is critical for testing geodynamic models and climatic changes at the regional and global scale. The Lhasa block is a key region for unraveling the early history of the Tibetan Plateau. Distinct from
the underlying shallow-marine limestones, the Jingzhushan and Daxiong formations consist of conglomerate and sandstone deposited in alluvial-fan and braided-river systems. Both units were deposited at ca. 92 Ma, as constrained by interbedded tuff layers,
detrital zircons, and micropaleontological data. Provenance and paleocurrent analyses indicate that both units were derived from the same elevated source area located in the central-northern Lhasa block. These two parallel belts of coeval conglomerates record a major change in paleogeography of the source region from a shallow seaway to a continental highland, implying initial topographic growth of an area over 160,000 km2, named here the Northern Lhasaplano. The early Late Cretaceous topographic growth of the Northern Lhasaplano was associated with the demise of Tethyan seaways, thrustbelt development, and crustal thickening. The same paleogeographic and paleotectonic changes were recorded earlier in the Northern Lhasaplano than in the Southern Lhasaplano, indicating progressive topographic growth from north to south across the Bangong-Nujiang suture and Lhasa block during the Cretaceous. Similar to the Central Andean Plateau, the Northern Lhasaplano
developed by plate convergence above the oceanic Neo-Tethyan subduction zone before the onset of the India-Asia collision.
Recent studies based on low-temperature chronology and sedimentol-ogy have proposed the existence of a proto-Tibetan Plateau (p-TP); however, the timing and mechanisms of its formation and evolution remain ambiguous. High-Sr/Y rocks are an important petrological indicator of thickening. Here, we compile geochemical data of Cretaceous rocks to interpret their petrogenesis and to constrain deep geodynamic processes. Geochemical characteristics, in combination with zircon Hf isotopic compositions, indicate that the high-Sr/Y rocks were derived from the partial melting of thickened juvenile lower crust, with or without contamination by mantle peridotite. Comparing geochronological and geochemical data, we observe a correlation between magma migration and the composition of high-Sr/Y rocks. Based on these observations, we propose a revised tectonomagmatic evolution model for central Tibet, involving crustal thickening, retreating delamination, and breakoff. Our research suggests that the rapid uplift of the p-TP was a consequence of the removal of isostatic load during the Mesozoic.
The Late Paleogene surface height and paleoenvironment for the core area of the Qinghai-Tibetan Plateau (QTP) remain critically unresolved. Here, we report the discovery of the youngest well-preserved fossil palm leaves from Tibet. They were recovered from the Late Paleogene (Chattian), ca. 25.5 ± 0.5 million years, paleolake sediments within the Lunpola Basin (32.033°N, 89.767°E), central QTP at a present elevation of 4655 m. The anatomy of palms renders them intrinsically susceptible to freezing, imposing upper bounds on their latitudinal and altitudinal distribution. Combined with model-determined paleoterrestrial lapse rates, this shows that a high plateau cannot have existed in the core of Tibet in the Paleogene. Instead, a deep paleovalley, whose floor was <2.3 km above mean sea level bounded by (>4 km) high mountain systems, formed a topographically highly varied landscape. This finding challenges prevailing views on tectonic processes, monsoon dynamics, and the evolution of Asian biodiversity.
Understanding the dynamics of double-thickening and uplifting of the Tibetan crust requires constraints on the magnitude and timing of crustal shortening. New elongation/inclination (E/I)-corrected paleomagnetic data from ~26–22 Ma sediments indicate that the latitude of southern Tibet in the early Miocene was 31.1/−6.8/+5.2°N, not significantly different from today. This implies that the southern margin of Asia, which was at 21–24°N latitude from the Late Cretaceous to the early Eocene, advanced 8–10° northward between the early Eocene and the latest Oligocene. Our results therefore suggest that at least 900–1100 km of continental shortening and significant regional uplift of the plateau occurred between the early Eocene and late Oligocene. Our results suggest that N-S intra-Asian convergence was considerably reduced around 26 Ma, corresponding to a transition from compression to extension within the Tibetan Plateau.
Understanding the behavior of the global climate system during extremely warm periods is one of the major themes of paleoclimatology. Proxy data demonstrate that the equator-to-pole temperature gradient was much lower during the mid-Cretaceous "supergreenhouse" period than at present, implying larger meridional heat transport by atmospheric and/or oceanic circulation. However, reconstructions of atmospheric circulation during the Cretaceous have been hampered by a lack of appropriate datasets based on reliable proxies. Desert distribution directly reflects the position of the subtropical high-pressure belt, and the prevailing surface-wind pattern preserved in desert deposits reveals the exact position of its divergence axis, which marks the poleward margin of the Hadley circulation. We reconstructed temporal changes in the latitude of the subtropical high-pressure belt and its divergence axis during the Cretaceous based on spatio-temporal changes in the latitudinal distribution of deserts and prevailing surface-wind patterns in the Asian interior. We found a poleward shift in the subtropical high-pressure belt during the early and late Cretaceous, suggesting a poleward expansion of the Hadley circulation. In contrast, an equatorward shift of the belt was found during the mid-Cretaceous "supergreenhouse" period, suggesting drastic shrinking of the Hadley circulation. These results, in conjunction with recent observations, suggest the existence of a threshold in atmospheric CO2 level and/or global temperature, beyond which the Hadley circulation shrinks drastically.
Knowledge of the late Mesozoic topography and drainage system of the Tibetan Plateau is essential for understanding the Cenozoic tectonic dynamics of the plateau. However, systematic analyses of the pre-Cenozoic surface uplift history and sediment-routing systems of the Tibetan Plateau remain sparse. Here we present new results for paleocurrents and U-Pb detrital zircon geochronology from the Lanping Basin, a key junction in the southeastern (SE) Tibetan Plateau, and integrate multidisciplinary data sets to constrain sediment provenance and reconstruct paleotopography and its drainage system throughout the Cretaceous. Our results indicate that mid- to Late Cretaceous (ca. Albian−Santonian) tectonically induced surface uplift occurred in the SE Tibetan Plateau, leading to the build-up of an extensive topographic barrier, and resultant rain shadows in the interior of east Asia. Superimposition of this topographic pattern by uplands in the eastern margin of Asia meant that the Cretaceous topography of east Asia was characterized by an enclosed paleo-relief pattern that was high in both the east and west, with drainage from the east and west to the south, contrasting with previously proposed configurations. This topographic pattern interrupted the atmospheric circulation pattern and generated widespread intracontinental desertification and drainage network evolution in east Asia. Our study constrains a key part of the late Mesozoic growth of the Tibetan Plateau prior to the Cenozoic collision between India and Eurasia and will improve our understanding of the paleoclimate, atmospheric circulation, and modern drainage system evolution of the east Asian continent.
Intermontane deserts are an important type of arid‐climate sedimentary system. Although rare at present, the sedimentary records of intermontane deserts reveal their widespread development in past greenhouse periods, and they might develop in the near future in response to ongoing global warming. Determination of the provenance of sand supplied for the construction of intermontane deserts is important to gain improved understanding of the potential impact of future climate on environmental evolution in arid and semi‐arid regions. During the Cretaceous, a typical intermontane desert developed in the Xinjiang Basin, south‐east China. In this study, the origin, spatial variability, and transport pathways of both aeolian and alluvial–fluvial sediments in the Xinjiang intermontane desert are investigated by analyses of bulk‐rock petrography and detrital‐zircon U–Pb geochronology. These results demonstrate that the sand in the Xinjiang intermontane desert succession was mainly of extraneous origin and wind‐derived. The nearby South China Block and South China Magmatic Belt were primary sources, and the 1000 km distant western margin of Yangtze Block was an important secondary source. During the Late Cretaceous, the westerlies were stronger in the northern than in the southern hemisphere with doubled wind speeds. In such a climatic context, the results herein suggest that the ultra‐long‐distance aeolian sediment transport was likely further enabled by two factors: (i) the strengthening of intermittent westerly winds during short‐lived glacial episodes; and (ii) the presence of a low‐relief corridor that served as a transport pathway from source to sink.
The relative roles of tectonics and climate change in global and regional desertification are not well constrained. Previous studies have emphasized the role played by climate change as a dominant cause of southeastern (SE) Asia desertification during the mid-Late Cretaceous. The effect of early uplift of the Tibetan Plateau prior to the collision between Eurasia and India on regional desertification remains poorly understood. We present a comprehensive set of provenance data on two aeolian sequences deposited in the Simao Basin and Khorat Plateau desert environments adjacent to southeast Tibet. Our provenance results suggest that the aeolian sandstones of the Pashahe Formation in the Simao Basin were largely recycled from exposed sedimentary rocks of the Songpan-Garze terrane, Southern Qiangtang terranes, and northern Yangtze Block with minor contributions from the magmatic rocks of the Tengchong and Southern Qiangtang terranes. Combined with other evidence, provenance results indicate the source areas started to grow and to be rapidly unroofed and determined the birth of the transcontinental southerly flowing paleo-river, which carried the sand to be stored. In contrast, the Phu Thok aeolian sandstones in the Khorat Plateau were predominantly sourced from the exposed Sibumasu igneous rocks together with recycled detritus in the Sukhothai Arc terrane, which was possibly transported by a local river. Hence, our thesis is that elevated topography caused by the closure of the Bangong-Nujiang Mesotethys profoundly affected the atmospheric circulation and drainage development, leading to mid-Late Cretaceous desertification across SE Asia.
The precollisional location and shape of the Lhasa terrane are crucial for constraining the closure of the Neo-Tethys Ocean and the ensuing India-Asia collision; however, estimation of these features of the Lhasa terrane remains highly controversial. Here, we carried out a new paleomagnetic investigation on the Lower Cretaceous Duoni Formation red beds in the central-eastern Lhasa terrane. The tilt-corrected site-mean direction is declination (Ds) = 339.0°, inclination (Is) = 26.8°, ks = 78.4, and α95 = 2.3° (k—precision parameter; α95—the radius that the mean direction lies within 95% confidence; s—stratigraphic coordinates) (N = 50), corresponding to a paleopole at 64.2°N, 324.2°E, with A95 = 1.9° (A95—the radius that the mean pole lies within 95% confidence). These new paleomagnetic data pass a positive fold test and indicate that the studied area was located at 14.3 ± 1.9°N during the Early Cretaceous. No significant inclination shallowing is present in the Lower Cretaceous Duoni Formation red beds. Our new results, combined with previously published reliable Cretaceous paleomagnetic results, show that the Lhasa terrane was located at a paleolatitude of ∼22.9°N to 10.1°N from west to east and was oriented at ∼298°−296° prior to India-Asia collision.
Southeastern Eurasia is a global window to the Cretaceous paleoclimate and lithosphere coupling. China contains one of the most complete and complex sedimentary records of Mesozoic desert basins on planet Earth. In this study, we perform the spatio-temporal tracking of 96 Cretaceous palaeoclimate indicators during 79 Myr which reveal that the plateau paleoclimate archives from East Asia resulted from an Early to Mid-Cretaceous ocean-atmosphere coupling and a shift to a preponderant role of Late Cretaceous lithosphere dynamics and tectonic forcing on high-altitude depositional systems linked to the subduction margins of the Tethys and Paleo-Pacific realms beneath the Eurasian plate. The crustal response to tectonic processes linked with the spatio-temporal evolution of the Tethyan and Paleo-Pacific margins defined the configuration of major sedimentary basins on this region. The significant increase and decrease in the number of active sedimentary basins that occur during the Cretaceous, from 16 in the Early Cretaceous, to 28 in the Mid-Cretaceous, and a decreasing to 11 sedimentary basins in the Late Cretaceous, is a direct response of lithospheric dynamics associated with the two main subduction zones (Tethys and Pacific domains). A shift in subduction style from an Early Cretaceous Paleo-Pacific Plate slab roll back to a Late Cretaceous flat-slab mode might have triggered regional plateau uplift, blocked intraplate volcanism, thus enhancing the denudation and sediment availability, and created wind corridors that led to the construction and accumulation of extensive Late Cretaceous aeolian sandy deserts (ergs) that covered Mid-Cretaceous plateau salars. At the same time, plateau uplift associated with crustal thickening following terrane assembly in the Tethyan margin triggered altitudinal cryospheric processes in sandy desert systems. Evidence of an active Cretaceous cryosphere in China include Valanginian-Hauterivian glacial debris flows, Early Aptian geochemical signature of melt waters from extensive ice sheets, and Cenomanian–Turonian ice-rafted debris (IRDs). These cryospheric indicators suggest an already uplifted plateau in southeastern Eurasia during the Cretaceous, and the marked correlation between cold plateau paleoclimate archives and marine records suggests a strong ocean-atmosphere coupling during Early and Mid-Cretaceous cold snaps. We thus conclude that lithospheric tectonics during Cretaceous played a fundamental role in triggering high-altitude basin desertification and spatio-temporal plateau paleohydrology variability in the Cretaceous of south-eastern Eurasia.
The timing of the initial India–Asia collision and the mechanisms that led to the eventual formation of the high (>5 km) Tibetan Plateau remain enigmatic. In this Review, we describe the spatio-temporal distribution and geodynamic mechanisms of surface uplift in the Tibetan Plateau, based on geologic and palaeo-altimetric constraints. Localized mountain building was initiated during a Cretaceous microcontinent collision event in central Tibet and ocean–continent convergence in southern Tibet. Geological data indicate that India began colliding with Asian-affinity rocks 65–60 million years ago (Ma). High-elevation (>4 km) east–west mountain belts were established in southern and central Tibet by ~55 Ma and ~45 Ma, respectively. These mountain belts were separated by ≤2 km elevation basins centred on the microcontinent suture in central Tibet, until the basins were uplifted further between ~38 and 29 Ma. Basin uplift to ≥4 km elevation was delayed along the India–Asia suture zone until ~20 Ma, along with that in northern Tibet. Delamination and break-off of the subducted Indian and Asian lithosphere were the dominant mechanisms of surface uplift, with spatial variations controlled by inherited lithospheric heterogeneities. Future research should explore why surface uplift along suture zones — the loci of the initial collision — was substantially delayed compared with the time of initial collision. The geodynamic mechanisms and timing of Tibetan Plateau formation are debated, but are critical to understanding tectonic–climatic links. This Review discusses the stages of Tibetan Plateau evolution, and highlights that inherited weaknesses from pre-Cenozoic tectonic events influenced its variable surface uplift history. The Tibetan Plateau did not get uplifted as a large entity or grow systematically outward from the India–Asia suture (IAS), because lithospheric heterogeneities in Asia imparted by pre-Cenozoic tectonic events created relatively weak and strong zones that deformed differently during collision.Cretaceous tectonic events built embryonic mountains belts and weakened the lithosphere in southern and central Tibet.Continental Asian detritus appeared in Indian continental margin sedimentary rocks by 65–60 million years ago (Ma). The most conservative interpretation based on available geologic constraints is that these sediments mark the initiation of India–Asia collision.The quest to further quantify the history of surface elevation change across Tibet spurred the field of quantitative palaeo-altimetry, such as measurement of oxygen and hydrogen isotopes in palaeo-water proxies, carbonate clumped isotope thermometry and fossil leaf physiognomy.Quantitative palaeo-altimetry suggests that high (≥4 km) elevations were obtained in southern Tibet by ~55 Ma and in central Tibet by ~45 Ma, whereas an intervening valley remained at <2 km elevation until between ~38 and 29 Ma. The IAS zone and Himalaya Mountains were rapidly uplifted from <3 km to near-modern elevations at ~20 Ma.Subcrustal processes such as subduction, delamination and break-off of Indian and Asian continental lithosphere were important tectonic events during the formation of the Tibetan Plateau. The Tibetan Plateau did not get uplifted as a large entity or grow systematically outward from the India–Asia suture (IAS), because lithospheric heterogeneities in Asia imparted by pre-Cenozoic tectonic events created relatively weak and strong zones that deformed differently during collision. Cretaceous tectonic events built embryonic mountains belts and weakened the lithosphere in southern and central Tibet. Continental Asian detritus appeared in Indian continental margin sedimentary rocks by 65–60 million years ago (Ma). The most conservative interpretation based on available geologic constraints is that these sediments mark the initiation of India–Asia collision. The quest to further quantify the history of surface elevation change across Tibet spurred the field of quantitative palaeo-altimetry, such as measurement of oxygen and hydrogen isotopes in palaeo-water proxies, carbonate clumped isotope thermometry and fossil leaf physiognomy. Quantitative palaeo-altimetry suggests that high (≥4 km) elevations were obtained in southern Tibet by ~55 Ma and in central Tibet by ~45 Ma, whereas an intervening valley remained at <2 km elevation until between ~38 and 29 Ma. The IAS zone and Himalaya Mountains were rapidly uplifted from <3 km to near-modern elevations at ~20 Ma. Subcrustal processes such as subduction, delamination and break-off of Indian and Asian continental lithosphere were important tectonic events during the formation of the Tibetan Plateau.
This study recognises and identifies the Late Cretaceous aeolian desert system from the Jianshi Basin, located in the intra-continental orogen within the Yangtze Block, South China. Erg deposits comprise aeolian dunes and dry aeolian sandsheets with alluvial facies associations at the margin and show an alluvial-aeolian depositional system. Palaeowind reconstruction of aeolian dune foresets showed that the dominant prevailing winds were westerlies, followed by northeasterlies and subordinate northwesterlies and southeasterlies. It is possible that monsoon rains recharged the water inflow system and caused the development of fluvial sand bodies at the margin of the Jianshi desert during the early deposition stage. The alluvial deposits in the study area were related to regional tectonism, while the dry aeolian system was dominated by mid- and low-latitudinal subtropical highs and the monsoonal climate. Orogenic topography, combined with planetary-scale subtropical high-pressure systems, blocked the transport of moisture, enclosed the low-lying land, and led to the aridification and development of desert depositional systems in the East Asian interior. Moreover, fault-controlled subsidence provided accommodation space in desert basins for alluvial and aeolian deposits. Based on the results obtained from palaeowind reconstructions, the divergent axis of subtropical highs during the Late Cretaceous was located in mid- and low-latitude areas of the Jianshi, Jianghan, Xinjiang, and Hengyang basins in South China. The relatively scattered nature of palaeowinds in the Jianshi Basin and adjacent deserts may indicate a seasonal drift in the divergent axis under the influence of a monsoonal climate.
Winter supercooling of oasis waters in hyper‐arid plateau deserts leads to the formation of ice floes on oases water surfaces. Multi‐year satellite imagery from recent oases in the Badain Jaran Desert (China) reveals dynamic cryospheric processes including ice floe, ice jams abutting on border ice, hinge and transverse cracks, multiple ice lobes related to aufeis formation on the ice floe surface indicating oases water level oscillations linked with short‐term variations of the groundwater input. Oasis ice floe break up and transportation by strong desert winds produce an effective gouge and abrasion mechanism of oasis margin sediments, incorporating them both into the oasis bottom, and as supra‐ice floe debris that ultimately will be released to the bottom of the oasis as dropstones as the ice cover melts. Supercooling conditions in the Badain Jarain Desert oases suggest that anchor ice can form in the oases bottoms from fazil ice crystals generated in open supercooled oasis waters. Mud dropstones and diamicton in Cretaceous wet interdune facies from China suggest ice‐rafting processes in oases. Rounded and subangular mud intraclasts are mud boudins formed by in situ boudinage of mud interdune sediments due to the combined effect of compaction by prograding aeolian sediments and aufeis formation. Anchor ice formed in the oases bottoms lifted them up due to floatability and released them as dropstones to the oasis bottom when melted. Cryospheric processes in hyper‐arid oases are more active than expected and may play a significant role in intraclast reworking. The recognition of these processes is critical for Mesozoic palaeoclimates.
Cretaceous stratigraphy in the mid- to low-latitude Asia indicates that the climate was overall dry with large variations in aridity in timescales of 1–100 ka, different from the present-day monsoonal humid climate. To identify the possible mechanism for such variation, we modeled the Late Cretaceous climate using a fully coupled atmosphere-ocean general circulation model (AOGCM), Community Earth System Model version 1.2 (CESM1.2), under different CO2 concentrations and orbital configurations. The simulation results show that the mid- to low-latitude Asia was generally dry during that time, consistent with reconstructions. The arid area decreases and the semi-arid area increases with the increase of CO2 concentration, but the change in total area is small even when CO2 is increased by 8 folds. In contrast, the area of dryland can increase by ~67% or 500% depending on how dryness is defined, when the orbital configuration changes from one in which the northern hemispheric summer receives the most solar insolation to one in which it receives the least solar insolation. Therefore, the mid- to low-latitude Asia was likely going through dramatic dry-humid cycles at orbital timescale during the Late Cretaceous, similar to the Saharan region during the Late Miocene-Pleistocene.
The collision between the Qiangtang and Lhasa blocks is a critical factor in understanding the geodynamics of the central Tibetan Plateau. However, the process of the Qiangtang-Lhasa collision remains contentious. A direct way to study the history of the Qiangtang-Lhasa collision would be to determine the evolution of the paleolatitude positions of the Qiangtang and Lhasa blocks during the Jurassic-Cretaceous. In this study, we present a combined paleomagnetic and geochronological study of the Early Cretaceous volcanic rocks dated at ~120–115 Ma in the western Qiangtang block. Stepwise thermal demagnetization succeeded in isolating the high-temperature characteristic directions of the samples. The tilt-corrected mean direction of the 16 sampling sites was Ds = 60.9°, Is = 45.9° with ɑ95 = 4.4°, which indicates that the Qiangtang block was situated at 27.6 ± 5.0°N during the Early Cretaceous (~120–115 Ma) (reference point: 32.9°N, 83.5°E). Our new data combined with previous reliable Cretaceous paleomagnetic results for the Lhasa block indicate that the collision between the western parts of the Qiangtang and Lhasa blocks may occur later than 115 Ma. The extent of the western segment of the Bangong-Nujiang Tethys Ocean was ~825 ± 600 km (7.5° ± 5.5° in latitude) at 120–115 Ma.
The Late Cretaceous Honghuatao Formation includes a succession of thick clastic sedimentary sequences which are widely exposed in northwestern Jianghan Basin, central China. Here, detailed sedimentological and facies architectural analyses are performed allowing to re-interpret and identify the controversy for sedimentary environment and to investigate the paleoclimatic condition. The Honghuatao stratigraphic sequence includes eolian dunes and dry interdunes deposits with fluvial channel deposits at the bottom and top. The vertical change between fluvial and eolian systems indicates alternating wet and dry climate. At the same time, the provenance analysis combined with the paleocurrents from the W, NW, and NE indicates that Huangling Dome, South Qinling Belt and Dabie Orogen supply the main detrital source for the Honghuatao Formation. The Late Cretaceous first rifting subsidence in the Jianghan Basin provided accommodation space for the preservation of the aeolian accumulation. Moreover, the existence of the mountain belts around the basin, that is, the orographic effect, precluded the winds from transporting humidity to the interior of the Jianghan Basin, generating the desert system. This study shows that the formation of eolian deposits in the Honghuatao Formation and coeval strata in numerous adjacent basins was a sedimentary response to the prevailing desert climate in the mid-to low-latitude areas of the Northern Hemisphere during the Late Cretaceous, which was predominately controlled by the subtropical high-pressure system on a planetary scale.
Along with intensification of global warming, severe desertification has already impaired human sustainable development. In a near-future greenhouse world, the total area of desert will increase, and new types of desert may emerge. During the “greenhouse” Cretaceous, conventional large paleo-ergs developed in broad topographic basins, and many possible ergs developed in small-scale intermountain basins, which are unusual in near-modern times and less studied. A comprehensive study of their sedimentary architecture and mechanisms would refine our interpretation of desertification in a near-future “greenhouse” world. The Xinjiang Basin is a typical small-scale intermountain basin in Southeast China that formed >300 m of successive aeolian deposits during the early Late Cretaceous. In this study, we applied detailed facies and architecture analyses to the Tangbian Formation (K2t) in 16 outcrops throughout the Xinjiang Basin and reconstructed a three-dimensional sedimentary model for the intermountain ergs. We confirmed that the Tangbian Formation formed in a typical intermountain paleo-erg and summarized in detail the differences in sedimentary architecture between intermountain ergs and broad topographic ergs. We noticed that the “greenhouse” state during the Late Cretaceous seems to have been suitable for the development of ergs in intermountain basins due to the hot, arid climate conditions and penetrating winds with sufficient transport capacity. Therefore, we suggest that in addition to the ongoing expansion of broad topographic ergs, the emergence and development of intermountain ergs in a near-future “greenhouse” world would also contribute to global desert expansion and massive desertification.
The Cretaceous Period (145-66 Ma) provides an opportunity to obtain insights into the adaptation of the climate system to increased atmospheric greenhouse gas concentrations. The organic paleothermometer TEX86 is one of the few proxies available for reconstructing quantitative estimates of upper ocean temperatures of this time period. Here we show that the sedimentary TEX86 signal in the Early Cretaceous North and South Atlantic shows systematic differences to other Cretaceous samples. In particular, the relative increase in the fractional abundances of the crenarchaeol isomer compared to crenarchaeol exhibits similarities with surface sediments from the modern Mediterranean and Red Sea. Dedicated climate model simulations suggest that the formation of warm and saline deep waters in the restricted North and South Atlantic may have influenced TEX86 export dynamics leading to a warm bias in reconstructed upper ocean temperatures. Applying a regional calibration from the modern Mediterranean and Red Sea to corresponding TEX86 data significantly improves the model-data fit for the Aptian Oceanic Anoxic Event 1a and the overall comparison with other temperature proxies for the Early Cretaceous. Our results demonstrate the need to consider regional and temporal changes of the TEX86-temperature relation for the reconstruction of deep-time ocean temperatures.
The Zoige plateau, Longmenshan thrust belt and Sichuan Basin on the eastern margin of the Tibetan Plateau constitute a united plateau-mountain-basin geodynamic system and the borehole Hongcan 1 (Well HC1) in the Zoige block provides extremely valuable materials for unraveling the uplift, propagation mechanism and eastward extension of the Tibetan Plateau. Based on the structural restoration and low-temperature thermochronology study of the Well HC1, combined with the previous published low-temperature thermochronology and paleo-elevation data, it is proposed that a paleo-plateau, here referred to as the Zoige paleo-plateau, had developed in the eastern Tibetan Plateau prior to the India-Asia collision during the Mesozoic, which is further demonstrated from several aspects such as basement tectonic attribution, deformation, crustal shortening and thickening, and sedimentary records. The structural recovery of the drilling well profile of the Well HC1 reveals that about 46% of the thickness (>7 km of the Triassic flysch strata) was actually caused by structural repetition. The extensive occurrence of the late Triassic adakitic granites and estimated crustal thickness through the Sr/Y ratio of the neutral magmatic rocks imply that substantial crustal thickening occurred in the Songpan-Ganzi area in the eastern Tibetan Plateau during the late Triassic. Multiple low-temperature thermochronology analyses for the Well HC1 [zircon (U-Th)/He, apatite fission track and (U-Th)/He)] reveal that the Zoige block experienced two rapid cooling events at ~ 120 Ma B. P. and ~80 Ma B. P. (Cretaceous) respectively, with a cumulative exhumation thickness of about 5 km, followed by an extremely slow cooling process thereafter, suggesting that the Zoige block has evolved into a peneplain with significant topography since late Cretaceous, and has been passively uplifted to the present elevation during the entire Cenozoic in a state of near-zero erosion. Therefore, the Zoige block in the eastern Tibetan Plateau has become a plateau no later than the end of the Cretaceous. It is considered that the Zoige paleo-plateau might include most of the Songpan-Ganzi area covered by the Triassic flysch strata, and they connect in the west to the Qiangtang paleo-plateau and form the Qiangtang-Zoige paleo-plateau. The formation of the Zoige paleo-plateau not only caused important provenance change in the west margin of Sichuan Basin during the mid-Cretaceous, but also aggravated the Cretaceous aridification in the eastern Tibetan Plateau and lead to a lot of desert sedimentation and salt deposition. The proposition of the Zoige paleo-plateau may deepen the understanding of the uplift and growth process of the Tibetan Plateau, and promote the formation mechanism research of the Tibetan Plateau and its climate-environment-resource effects.
This study reassesses the terrestrial deposits of the Late Cretaceous Tangbian Formation in the western Xinjiang Basin of the South China block. Originally considered to be aqueous deposits, we reinterpret these strata as representing an extensive aeolian system in a desert environment. This paper suggests that the development of aeolian deposits in the Tangbian Fm. represents the culmination of the Late-Cretaceous desertification that followed the relatively humid early Late-Cretaceous epoch in the interior of South China. The area was dominated by subtropical high-pressure systems on a planetary scale, combined with coastal mountains caused by sustained orogenic activity. The interaction between subtropical high pressure systems and topographic conditions ultimately caused the development of a tropical desert climate, characterized by an extensive dry climbing aeolian dune system. We propose that the coastal mountains not only blocked moisture transport from the ocean and led to the aridification of South China interior, but also exerted a control and transformed the original prevailing surface-wind pattern.
Previous climate modeling studies suggest that the surface uplift of the Himalaya-Tibetan plateau (TP) is a crucial parameter for the onset and intensification of the East Asian monsoon during the Cenozoic. Most of these studies have only considered the Himalaya-TP in its present location between ∼26N and ∼40N despite numerous recent geophysical studies that reconstruct the Himalaya-TP 10 degree or more of latitude to the south during the early Paleogene. We have designed a series of climate simulations to explore the sensitivity of East Asian climate to the latitude of the Himalaya-TP. Our simulations suggest that the East Asian climate strongly depends on the latitude of the Himalaya-TP. Surface uplift of a proto-Himalaya-TP in the subtropics intensifies aridity throughout inland Asia north of ∼40N and enhances precipitation over East Asia. In contrast, the rise of a proto-Himalaya-TP in the tropics only slightly intensifies aridity in inland Asia north of ∼40N, and slightly increases precipitation in East Asia. Importantly, this climate sensitivity to the latitudinal position of the Himalaya-TP is non-linear, particularly for precipitation across East Asia. The simulated precipitation patterns across East Asia are significantly different between our scenarios in which a proto-plateau is situated between ∼11N and ∼25N and between ∼20N and ∼33N, but they are similar when the plateau translates northward from between ∼20N and ∼33N to its modern position. Our simulations, when interpreted in the context of climate proxy data from Central Asia, support geophysically-based paleogeographic reconstructions in which the southern margin of a modern-elevation proto-Himalaya-TP was located at ∼20N or further north in the Eocene.
The surface uplift of the Tibetan Plateau (TP) had important effects on the evolution of both the regional and global climate during the Cenozoic. Geological evidence indicated that the timing of the uplifts of the main and marginal TP was probably different. However, many previous modelling studies only investigated the effects of the uplift of the whole TP on climate under modern boundary conditions and it remained unclear what was the difference between the effects of the uplifts of the main and marginal TP on climate and how changed boundary conditions influenced these effects. We used numerical modelling to investigate these questions. Our modelling results indicated that the uplifts of the main and marginal TP had different effects on climate. In particular, under modern boundary conditions, the uplift of the main TP decreased annual precipitation throughout inland Asia and in South Asia, increased annual precipitation in East Asia, and markedly changed the summer and winter low-level winds in Asia. By contrast, the uplift of the marginal TP increased the annual precipitation in South Asia, strengthened the seasonality of winds and enlarged the monsoon domain in East Asia. Thus, although the main TP was the major part of the TP in spatial terms, its uplift did not have the dominant effects on climate in all aspects. Moreover, changes in the boundary conditions – for example, from modern to ~30 Ma – could further influence the effects of the uplifts of the whole TP and its sub-regions on climate, particularly for the precipitation in South Asia and monsoon domain in East Asia. These results highlighted the different effects of the uplifts of the main and marginal TP on climate and emphasized the importance of accompanied boundary conditions when investigating the effects of the uplifts of the whole TP and its sub-regions on climate.
The mid-Cretaceous constitutes a period of worldwide atmospheric and oceanic change associated with slower thermohaline circulation and ocean anoxic events, possible polar glaciations and by a changing climate pattern becoming controlled by a zonal planetary wind system and an equatorial humid belt. During the mid-Cretaceous, the subtropical high-pressure arid climate belt of the planetary wind system controlled the palaeolatitude distribution of humid belts in Asia as well as the spatial distribution of rain belts over the massive continental blocks at mid-low latitudes in the southern and northern hemispheres. Additionally, the orographic effect of the Andean-type active continental margin in East Asia hindered the transportation of ocean moisture to inland regions. With rising temperatures and palaeoatmospheric conditions dominated by high pressure systems, desert climate environments expanded at the inland areas of East Asia including those accumulated in the mid-Cretaceous of the Simao Basin, the Sichuan Basin, and the Thailand's Khorat Basin, and leading the Late Cretaceous erg systems in the Xinjiang Basin and Jianghan Basin. This manuscript presents evidences that allow to reinterpret previously considered water-laid sediments to be accumulated as windblown deposits forming part of extensive erg (sandy desert) systems. Using a multidisciplinary approach including petrological, sedimentological and architectural observations, the mid-Cretaceous (Albian-Turonian) Nanxin Formation from the Yunlong region of Lanping Basin, formerly considered to aqueous deposits is here interpreted as representing aeolian deposits, showing local aeolian-fluvial interaction deposits. The palaeowind directions obtained from the analysis of aeolian dune cross-beddings indicates that inland deserts were compatible with a high-pressure cell (HPC) existing in the mid-low latitudes of East Asia during the mid-Cretaceous. Compared with the Early Cretaceous, the mid-Cretaceous had extremely lower temperatures and pressure gradients, more arid climate, which is in accordance with the existing morphology of HPC, and the HPC was stable with little movement. Simultaneously, the deserts controlled by the mid-Cretaceous HPC were closer to the equator, indicating the shrinkage of the Hadley Cell relative to the Early Cretaceous.
Plateaus on earth can be subdivided into two categories: craton plateau and orogenic plateau. Craton plateau normally developed on Precambrian basement or stable craton, which is characterized by simple, homogeneous, stable, cold and strong old basement, such as Brazilian Plateau, Colorado Plateau, Ethiopia Plateau, South African Plateau, Middle Siberia Plateau, Deccan Plateau, and so on. Basement of orogenic plateau is always composed by different orogenic units. The orogenic plateau could be separated into subducted orogenic plateau and collisional orogenic plateau two groups. The Middle Andean Plateau, formed overlying eastward subducted Pacific plate, belongs the subducted orogenic plateau. While, the Tibetan Plateau possess complex and uninformed soft basements which have experienced multiple phase orogeny. New research results illustrate that the Tibetan Plateau begin uplifted during Early Cretaceous, it may be related with closure of Bangong-Nujiang Ocean at 120 similar to 140Ma. However, India-Asian collision (60 similar to 50Ma) and concomitantly low angle under thrust of Indian lithosphere beneath Tibetan Plateau lead to the Plateau finally elevated over 4000 similar to 5000m.
Paleoclimatic indicators suggest that the mid-Cretaceous was one of the warmest intervals of the Phanerozoic. The period of the mid-Cretaceous “super-greenhouse” also experienced an equator-to-pole temperature gradient much lower than that of the present day, implying greater meridional heat transport by the atmosphere and/or oceans. However, reconstructions of Cretaceous atmospheric circulation have been hindered by a lack of relevant datasets based on reliable proxies or direct geological evidence. Aeolian deposits provide direct information about paleoclimate, as well as the direction and intensity of paleo-wind in the interiors of continents. Using petrologic and sedimentologic observations, this study reassesses the terrestrial deposits of the mid-Cretaceous Mangang Formation in the Simao Basin of southwestern China. Originally considered to be aqueous deposits, we reinterpret these strata as representing aeolian transport in a desert environment. We suggest that the development of aeolian deposits in the Mangang Formation (and coeval strata in adjacent basins) was a local response to the prevailing desert climate in the mid- to low-latitudes of the Northern Hemisphere during the mid-Cretaceous, which were dominated by subtropical high-pressure systems on a planetary scale. In addition, with the closure of the Mesotethys Ocean, the intermontane basins of the South China, Simao, and Indochina blocks became more isolated from atmospheric circulation. Bidirectional subduction of the Bangong-Nujiang oceanic crust and the Izanagi Plate beneath East Asia led to the development of Andean-type margins, which created a rain-shadow effect in continental East Asia. These factors caused the development of a tropical desert climate, characterized by aeolian dunes and evaporite deposition. We speculate that the severe depletion of groundwater reservoirs via the desertification of East Asia may represent a previously unrecognized trigger for short-term sea-level changes during the ice-free Cretaceous greenhouse interval.
Proxy temperature reconstructions indicate a dramatic cooling from the Cenomanian to Maastrichtian. However, the spatial extent of and mechanisms responsible for this cooling remain uncertain, given simultaneous climatic influences of tectonic and greenhouse gas changes through the Late Cretaceous. Here we compare several climate simulations of the Cretaceous using two different Earth system models with a compilation of sea surface temperature proxies from the Cenomanian and Maastrichtian to better understand Late Cretaceous climate change. In general, surface temperature responses are consistent between models, lending confidence to our findings. Our comparison of proxies and models confirms that Late Cretaceous cooling was a widespread phenomenon and likely due to a reduction in greenhouse gas concentrations in excess of a halving of CO2, not changes in paleogeography.