Middle Miocene climate transition in the Tibetan Plateau: identification and significance

2021 ◽  
pp. 1-20
Author(s):  
Shijun Song ◽  
Lei Huang ◽  
Yongshu Zhang ◽  
Qi Zhang ◽  
Fei Zhou ◽  
...  
Keyword(s):  
Tibetan Plateau ◽  
Central Asia ◽  
Middle Miocene ◽  
Gamma Ray ◽  
Qaidam Basin ◽  
The Tibetan Plateau ◽  
Fine Grained ◽  
Climatic Optimum ◽  
Mixed Sediments ◽  
Climate Transition

Abstract The Middle Miocene Climatic Optimum is known for abrupt events during the global cooling trend of the past 20 Ma. Its identification in the Tibetan Plateau can help explain the cause of the critical Middle Miocene climate transition in Central Asia. In this study, fine-grained mixed sediments widely distributed in the Miocene Qaidam Lake in the northern Tibetan Plateau were used as a sensitive indicator for palaeoclimate. Their geochemical characteristics were investigated, together with an analysis of 2600 m long successive gamma-ray logging data from the whole JS2 drillcore, to understand the mid-Miocene climate transition in the Tibetan Plateau. By comparing the gamma-ray curve of the mixed sediments with global temperature, the Middle Miocene Climatic Optimum event can be easily identified. Further, the detailed petrological features and geochemical data of lacustrine fine-grained mixed sediments from a 400 m drillcore show oxidizing, high-sedimentation rate and brackish-saline water conditions in a semi-arid climate during the Middle Miocene period, demonstrating a dryer climate in the Qaidam Basin than in the monsoon-sensitive regions in Central Asia. These fine-grained mixed sediments have recorded climate drying before 15.3 Ma that represents a climatic transition within the Middle Miocene Climatic Optimum; increasing carbonate-rich mixed sediments, decreasing algal limestone layers and decreasing lacustrine organic matter are indicators of this transition. Regional tectonic events include the retreat of the Paratethys from Central Asia at ∼15 Ma and the synchronous tectonic reorganization of the Altyn-Tagh fault system and the northeastern Tibetan Plateau. We find that global climate change is the primary factor affecting the overall characteristics and changes of the Neogene climate in the Qaidam Basin, including the occurrence of the Middle Miocene Climatic Optimum and the cooling and drying tendency, while the regional events are a secondary factor.

scholarly journals Late Cenozoic continuous aridification in the western Qaidam Basin: evidence from sporopollen records

2013 ◽  
Vol 9 (2) ◽  
pp. 1485-1508 ◽  
Author(s):  
Y. F. Miao ◽  
X. M. Fang ◽  
F. L. Wu ◽  
M. T. Cai ◽  
C. H. Song ◽  
...  
Keyword(s):  
Tibetan Plateau ◽  
Middle Miocene ◽  
Qaidam Basin ◽  
East Asian ◽  
The Tibetan Plateau ◽  
Late Cenozoic ◽  
Plateau Uplift ◽  
Western Qaidam Basin ◽  
Global Cooling ◽  
Tibetan Plateau Uplift

Abstract. Cenozoic climate changes in inner Asia provide a basis for understanding linkages between global cooling, the Tibetan Plateau uplift, and possibly the development of the East Asian monsoon. Based on the compiled palynological results from the western Qaidam Basin, this study reconstructed an 18 Ma record of changing vegetation and paleoclimates since the middle Miocene. Thermophilic taxa percentages were highest between 18 and 14 Ma and decreased after 14 Ma, corresponding closely with the Middle Miocene Climatic Optimum (MMCO) between 18 and 14 Ma and the following global climatic cooling. After 3.6 Ma, the thermophilic taxa percentages further decreased, showing the inevitable relations with the ice-sheets enlargement in the North Hemisphere. During the same period of time, the increase in xerophytic taxa percentages and decrease in conifers percentages imply aridification in both the basin and surrounding mountains since 18 Ma. These results indicate that global cooling mainly controlled the climate change from a relative warm-wet stage to a cold-dry stage during the late Cenozoic at the western Qaidam Basin, and that the Tibetan Plateau uplift also contributed in contrast to the East Asian summer monsoon.

scholarly journals Intensified aridity in the Qaidam Basin during the Middle Miocene: constraints from ostracod, stable isotope, and weathering records

2017 ◽  
Vol 54 (3) ◽  
pp. 242-256 ◽  
Author(s):  
Bowen Song ◽  
Junliang Ji ◽  
Chaowen Wang ◽  
Yadong Xu ◽  
Kexin Zhang
Keyword(s):  
Stable Isotope ◽  
Tibetan Plateau ◽  
Chemical Weathering ◽  
Middle Miocene ◽  
Qaidam Basin ◽  
Global Climate ◽  
The Tibetan Plateau ◽  
Tectonic Events ◽  
Regional Tectonic ◽  
Climate Evolution

The thick and continuous Cenozoic successions in the Qaidam Basin provide an excellent paleoclimate archive. Here, we focus on the ostracod fauna, stable isotope records, and paleoweathering indices from a well-dated Cenozoic sedimentary section in the Qaidam Basin, to develop an understanding of Middle Miocene aridification in central Asia. Microfossil analyses suggest that the ostracod species diversity decreased suddenly after 13.3 Ma, and that the dominant ostracod genus shifted from Ilyocypris to Cyprideis. Stable isotope data from ostracod valves have displayed abrupt positive shifts of 3.75‰ in δ18O values and 5.28‰ in δ13C values since 13.3 Ma. The chemical index of weathering (CIW) and K2O/Na2O ratios decrease markedly after 13.3 Ma, reflecting a significant decrease in chemical weathering intensity. These combined and consistent observations suggest that the Qaidam Basin has experienced increased aridification since 13.3 Ma. The dating was obtained directly from previous magnetostratigraphic studies and can be correlated accurately with global climate evolution and regional tectonic events. A comparison of these results with global paleoclimatic records and previous geologic studies of the Tibetan Plateau revealed that global cooling, rather than uplift of the Tibetan Plateau, played a key role in the drying of the Qaidam Basin at approximately 13 Ma.

Paleolake salinity evolution in the Qaidam Basin (NE Tibetan Plateau) between ~42 and 29 Ma: Links to global cooling and Paratethys sea incursions

2021 ◽  
Author(s):  
Chengcheng Ye ◽  
Yibo Yang ◽  
Xiaomin Fang ◽  
Weilin Zhang ◽  
Chunhui Song ◽  
...  
Keyword(s):  
Climate Change ◽  
Tibetan Plateau ◽  
Middle Eocene ◽  
Qaidam Basin ◽  
Regional Climate ◽  
Regional Climate Change ◽  
Driving Mechanism ◽  
The Tibetan Plateau ◽  
Early Oligocene ◽  
Global Cooling

<p>Global cooling, the early uplift of the Tibetan Plateau, and the retreat of the Paratethys are three main factors that regulate long-term climate change in the Asian interior during the Cenozoic. However, the debated elevation history of the Tibetan Plateau and the overlapping climate effects of the Tibetan Plateau uplift and Paratethys retreat makes it difficult to assess the driving mechanism on regional climate change in a particular period. Some recent progress suggests that precisely dated Paratethys transgression/regression cycles appear to have fluctuated over broad regions with low relief in the northern Tibetan Plateau in the middle Eocene–early Oligocene, when the global climate was characterized by generally continuous cooling followed by the rapid Eocene–Oligocene climate transition (EOT). Therefore, a middle Eocene–early Oligocene record from the Asian interior with unambiguous paleoclimatic implications offers an opportunity to distinguish between the climatic effects of the Paratethys retreat and those of global cooling.</p><p>Here, we present a complete paleolake salinity record from middle Eocene to early Miocene (~42-29 Ma) in the Qaidam Basin using detailed clay boron content and clay mineralogical investigations. Two independent paleosalimeters, equivalent boron and Couch’s salinity, collectively present a three-staged salinity evolution, from an oligohaline–mesohaline environment in the middle Eocene (42-~34 Ma) to a mesosaline environment in late Eocene-early Oligocene (~34-~29 Ma). This clay boron-derived salinity evolution is further supported by the published chloride-based and ostracod-based paleosalinity estimates in the Qaidam Basin. Our quantitative paleolake reconstruction between ~42 and 29 Ma in the Qaidam Basin resembles the hydroclimate change in the neighboring Xining Basin, of which both present good agreement with changes of marine benthic oxygen isotope compositions. We thus speculated that the secular trend of clay boron-derived paleolake salinity in ~42-29 Ma is primarily controlled by global cooling, which regulates regional climate change by influencing the evaporation capacity in the moisture source of Qaidam Basin. Superimposed on this trend, the Paratethys transgression/regression cycles served as an important factor regulating wet/dry fluctuations in the Asian interior between ~42 and ~34 Ma.</p>

scholarly journals Evolution of the Yangtze River network, southeastern Tibet: Insights from thermochronology and sedimentology

Lithosphere ◽  
2019 ◽  
Vol 12 (1) ◽  
pp. 3-18
Author(s):  
Loraine Gourbet ◽  
Rong Yang ◽  
Maria Giuditta Fellin ◽  
Jean-Louis Paquette ◽  
Sean D. Willett ◽  
...  
Keyword(s):  
Tibetan Plateau ◽  
Yangtze River ◽  
Middle Miocene ◽  
Strike Slip ◽  
The Tibetan Plateau ◽  
Fluvial Incision ◽  
Upper Yangtze River ◽  
Southeastern Margin ◽  
The Upper Yangtze River ◽  
Southeastern Tibet

Abstract We performed apatite and zircon (U-Th)/He dating on a granitic pluton that has been offset by ∼10 km by motion on the sinistral strike-slip Xiangcheng fault in SW Sichuan, SE Tibetan plateau, where the Shuoqu River incises a deep valley before joining the upper Yangtze River. Mean ZHe cooling ages range from 49.5 ± 2.2 Ma to 68.6 ± 6.0 Ma. Samples located above 3870 m yield mean apatite (U-Th)/He ages ranging from 30.6 ± 1.4 Ma to 40.6 ± 2.7 Ma, whereas samples at lower elevations range from 9.8 ± 1.3 Ma to 14.6 ± 2.7 Ma. In the same region, Cenozoic continental sediments are exposed on the flanks of deep valleys. They consist of unsorted conglomerates and sandstones that partly fill a paleotopography. The sediments were deposited during an episode of rapid sedimentation, followed by incision that varies between 0.5 and 1.2 km. Thermal and exhumational modeling of the granite thermochronometric data indicates rapid cooling during the middle Miocene that was likely related to fluvial incision. Our findings suggest that the upper Yangtze River and its tributary (Shuoqu) were connected by the middle Miocene. Our modeling also supports the idea that the exhumation pattern during the Cenozoic in the southeastern margin of the Tibetan Plateau is spatially and temporally heterogeneous.

New Noctuidae species from China (Lepidoptera, Noctuoidea)

Zootaxa ◽  
2011 ◽  
Vol 2896 (1) ◽  
pp. 46
Author(s):  
P. GYULAI ◽  
L. RONKAY ◽  
A. SALDAITIS
Keyword(s):  
New Species ◽  
Tibetan Plateau ◽  
Central Asia ◽  
New Taxa ◽  
Light Trapping ◽  
Himalayan Region ◽  
Research Centre ◽  
The Tibetan Plateau ◽  
The Third ◽  
High Diversity

Collecting expeditions to China's Sichuan, Gansu and Qinghai provinces were conducted by the third author, along with Alessandro and Irene Floriani, during June 2009, April 2010 and July 2010. Light trapping yielded numerous noctuid moths including four new species, described herein. These new taxa reflect the high diversity of some genera (Hada, Billberg, 1820 ; Palaeamathes, Boursin, 1954) in SW China, and the biogeographical connections of the Tibetan Plateau to Central Asia (Lacanobia kitokia sp. n., L. contrastata (Bryk, 1942), L. mongolica Behounek, 1993, L. kirghisa Gyulai & Ronkay, 1998) and to the Himalayan Region (Palaeamathes serrulata sp. n. is close to P. harpegnoma (Hreblay & Ronkay, 1998). Acronyms for personal and institutional collections are as follows: AFM—Alessandro Floriani (Milan, Italy); ASV—Aidas Saldaitis (Vilnius, Lithuania); BJ—Janos Babics (Budapest, Hungary); DNK—Danny Nilsson (Kalvehave, Denmark); GRB—Gabor Ronkay (Budapest, Hungary); GBG/ZSM—Gottfried Behounek (Grafing, Germany) / Zoologische Staatssammlung, München (Germany); GYP—Peter Gyulai (Miskolc, Hungary); HHP – Henri Hoppe (Klein Pravtshagen, Germany); NRCV—Nature Research Centre (Vilnius, Lithuania); WSM—Wolfgang Speidel (München, Germany).

scholarly journals Changing Pattern of Water Level Trends in Eurasian Endorheic Lakes as a Response to the Recent Climate Variability

2021 ◽  
Vol 13 (18) ◽  
pp. 3705
Author(s):  
Xin Zhang ◽  
Abilgazi Kurbaniyazov ◽  
Georgiy Kirillin
Keyword(s):  
Climate Change ◽  
Tibetan Plateau ◽  
Central Asia ◽  
Climatic Factors ◽  
Hydrological Regime ◽  
Water Levels ◽  
The Tibetan Plateau ◽  
Lake Levels ◽  
Mongolian Plateau ◽  
Recent Climate

Lake level is a sensitive integral indicator of climate change on regional scales, especially in enclosed endorheic basins. Eurasia contains the largest endorheic zone with several large terminal lakes, whose water levels recently underwent remarkable variations. To address the patterns of these variations and their links to the climate change, we investigated the variability of levels in 15 lakes of three neighboring endorheic regions—Central Asia, Tibetan Plateau, and Mongolian Plateau. Satellite altimetry revealed a heterogeneous pattern among the regions during 1992–2018: lake levels increased significantly in Central Asia and the Tibetan Plateau but decreased on the Mongolian Plateau. The shifts to the increasing trend were detected since 1997 in Central Asia, since 1998 in the southern part of the Tibetan Plateau, and since 2005 in its northern part. The shift in air temperatures around 1997 and the precipitation shifts around 1998 and 2004 contributed to the trend’s turning points, with precipitation being the major contributor to the heterogeneous pattern of lake levels. Our findings reveal the linkage of the heterogeneous pattern of lake levels to climatic factors in the endorheic basins, providing a further understanding of the hydrological regime in the Eurasian endorheic zone and its sensitivity to climate change.

scholarly journals Monitoring 40-Year Lake Area Changes of the Qaidam Basin, Tibetan Plateau, Using Landsat Time Series

2019 ◽  
Vol 11 (3) ◽  
pp. 343 ◽  
Author(s):  
Huiying Li ◽  
Dehua Mao ◽  
Xiaoyan Li ◽  
Zongming Wang ◽  
Cuizhen Wang
Keyword(s):  
Tibetan Plateau ◽  
Structural Equation ◽  
Environmental Changes ◽  
Human Impacts ◽  
Qaidam Basin ◽  
Salt Lakes ◽  
Anthropogenic Factors ◽  
The Tibetan Plateau ◽  
Lake Area ◽  
Landsat Images

Areal changes of high-altitude inland lakes on the Qaidam Basin (QB) of the Tibetan Plateau are reliable indicators of climate change and anthropogenic disturbance. Due to the physical difficulties to access, our knowledge of the spatial patterns and processes of climatic and human impacts on the Basin has been limited. Focusing on lake area changes, this study used long-term Landsat images to map the patterns of lakes and glaciers in 1977, 1990, 2000, and 2015, and to monitor the spatially explicit changes of lakes between 1977 and 2015. Results revealed that the total number of lakes (area > 0.5 km2) increased by 18, while their total area expanded by 29.8%, from 1761.5 ± 88.1 km2 to 2285.9 ± 91.4 km2. Meanwhile, glaciers have decreased in area by 259.16 km2 in the past four decades. The structural equation model (SEM) was applied to examine the integrative effects of natural and anthropogenic factors on lake area. Precipitation change exhibited the most significant influence on lake area in the QB from 1977 to 2000, while human activities also played an important role in the expansion of lakes in the QB in the period 2000–2015. In particular, extensive exploitation of salt lakes as mining resources resulted in severe changes in lake area and landscape. The continuously expanding salt lakes inundated the road infrastructure nearby, posing great threats to road safety. This study shed new light on the impacts of recent environmental changes and human interventions on lakes in the Qaidam Basin, which could assist policy-making for protecting the lakes and for strengthening the ecological improvement of this vast, arid basin.

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