Distinguishing tectonic versus climatic forcing on landscape evolution: An example from SE Tibetan Plateau

2020 ◽  
Vol 133 (1-2) ◽  
pp. 233-242 ◽  
Author(s):  
Fangbin Liu ◽  
Martin Danišík ◽  
Dewen Zheng ◽  
Kerry Gallagher ◽  
Junsheng Nie
Keyword(s):  
Tibetan Plateau ◽  
Middle Miocene ◽  
Asian Summer Monsoon ◽  
Late Eocene ◽  
Crustal Shortening ◽  
Lateral Extrusion ◽  
Granite Belt ◽  
Cooling Phase ◽  
Forcing Mechanisms ◽  
Exhumation History

Abstract Distinguishing climate from tectonic forcing in shaping the Earth’s surface has been a long-standing issue in the Earth sciences. Great debate exists regarding when and how the SE Tibetan Plateau achieved its current low-relief topography, and both lateral extrusion and lower crust flow have been proposed as the dominant mechanism. Reconstruction of the exhumation history of the SE Tibetan Plateau is key to understanding these formation processes and resolving the significance of different forcing mechanisms. Here we report zircon and apatite (U-Th)/He ages from steep transects across the Lincang granite belt of the SE Tibetan Plateau. Our results reveal a two-stage exhumation history during the Cenozoic with rapid cooling phases in the late Eocene and the middle Miocene. In the late Eocene, the climate was generally dry and there is plenty of evidence for increased extrusion and upper crustal shortening. We suggest tectonic processes are responsible for the first inferred cooling. In contrast, the Asian summer monsoon precipitation increased during the middle Miocene, and we posit the middle Miocene cooling phase records a phase of rapid river incision triggered by the intensified precipitation and associated fault movements. The results are consistent with recent paleo-altimetry work in this region suggesting that the present-day topography of the SE Tibetan Plateau had been largely constructed by the late Eocene. Together, these data suggest that extrusion and/or upper crustal shortening setup the first order topography of the SE Tibetan Plateau, which was then modified by climate-triggered fluvial incision and feedbacks initiated in the middle Miocene.

Late Cenozoic two-phase rapid exhumation of the Daliang Mountains, Southeastern Tibetan Plateau

2021 ◽  
Author(s):  
Haijia Lei ◽  
Xiaoming Shen ◽  
Xijun Liu ◽  
Xiudang Tang ◽  
Shiming Zhang
Keyword(s):  
Climate Change ◽  
Tibetan Plateau ◽  
Middle Miocene ◽  
Asian Monsoon ◽  
East Asian Monsoon ◽  
East Asian ◽  
Late Cenozoic ◽  
Two Phase ◽  
Southeastern Tibetan Plateau ◽  
Exhumation History

<p>The southeastern Tibetan Plateau experienced significant tectonic uplift, fault activity, climate change and reorgnization of fluvial systems during the late Cenozoic. All these processes were probably accompanied by rapid rock exhumation. Therefore, rock exhumation history in this region could provide a key to reveal the interaction between tectonics, climate and surface processes. Here, we report new apatite and zircon (U-Th)/He dates from a ~1200 m granite vertical profile, located at Shimian county in the Daliang Mountains, southeastern Tibetan Plateau. The age-elevation relationship and thermal history simulation exhibit a two-phase rock exhumation history, one at ~25 Ma (~1 km/Myr) and a second moderate exhumation from ~15 Ma to present (~ 0.2 km/Myr). This two-phase rapid exhumation history is consistent with that of Longmen Shan and Jiulong in the adjacent areas. For the first phase in Oligocene, abundant geological evidence indicates that it was related to the regional uplift caused by the transpressional deformation during India-Asia convergence. However, there are two distinct explanations for the rapid exhumation from ~15 Ma to present: one group suggested this exhumation was related to the rapid river incision caused by regional uplift; By contrast, based on paleo-altimetry data another group proposed the uplift was ceased before the late Miocene in southeastern Tibetan Plateau, and then the enhanced rainfall caused by the East Asian monsoon resulted in rapid exhumation since the Middle Miocene. Our study suggests that the fast exhumation in southeastern Tibetan Plateau since ~15 Ma cannot be attributed solely to the regional uplift or the intensification of Asian monsoon. Combined with the activity history of the Anninghe fault in the study area and the East Asian monsoon evolution history, we suggest that the regional rock exhumation of southeastern Tibetean Plateau since the Middle Miocene could be the result of the combination of tectonic activity and climate change.</p>

Exhumation History of the Gangdese Batholith, Southern Tibetan Plateau: Evidence from Apatite and Zircon (U-Th)/He Thermochronology

2013 ◽  
Vol 121 (2) ◽  
pp. 155-172 ◽  
Author(s):  
Jingen Dai ◽  
Chengshan Wang ◽  
Jeremy Hourigan ◽  
Zhijun Li ◽  
Guangsheng Zhuang
Keyword(s):  
Tibetan Plateau ◽  
History Of ◽  
Southern Tibetan Plateau ◽  
Exhumation History

scholarly journals Direct radiative effects of dust aerosols emitted from the Tibetan Plateau on the East Asian summer monsoon – a regional climate model simulation

2017 ◽  
Author(s):  
Hui Sun ◽  
Xiaodong Liu ◽  
Zaitao Pan
Keyword(s):  
Tibetan Plateau ◽  
Regional Climate Model ◽  
East Asian Summer Monsoon ◽  
Asian Monsoon ◽  
Climate Model ◽  
Asian Summer Monsoon ◽  
Regional Climate ◽  
East Asian ◽  
Dust Aerosols ◽  
Asian Summer

Abstract. While dust aerosols emitted from major Asian sources such as Taklimakan and Gobi Deserts have been shown to have strong effect on Asian monsoon and climate, the role of dust emitted from Tibetan Plateau (TP) itself, where aerosols can directly interact with the TP heat pump because of their physical proximity both in location and elevation, has not been examined. This study uses the dust coupled RegCM4.1 regional climate model to simulate the spatiotemporal distribution of dust aerosols originating in the TP and their radiative effects on the East Asian summer monsoon (EASM) during both heavy and light dust years. Two 20-year simulations with and without the dust emission from TP showed that direct radiative cooling in the mid-troposphere induced by the TP locally produced dust aerosols resulted in an overall anticyclonic circulation anomaly in the low-troposphere centered over the TP region. The northeasterly anomaly in the EASM region reduces its strength considerably. The simulations found a significant negative correlation between the TP column dust load produced by local emissions and the corresponding anomaly in the EASM index (R=−0.41). The locally generated TP dust can cause surface cooling far downstream in eastern Mongolia and northeastern China through stationery Rossby wave propagation. Although contribution to the total Asian dust source from within TP (mainly Qaidam Basin) is relatively small, its impacts on Asian monsoon and climate seems disproportionately large, likely owning to its higher elevation within TP itself.

scholarly journals Numerical study of surface energy partitioning on the Tibetan Plateau: comparative analysis of two biosphere models

2009 ◽  
Vol 6 (6) ◽  
pp. 10849-10881
Author(s):  
J. Hong ◽  
J. Kim
Keyword(s):  
Comparative Analysis ◽  
Tibetan Plateau ◽  
Surface Energy ◽  
Summer Monsoon ◽  
Numerical Study ◽  
Asian Summer Monsoon ◽  
Energy Partitioning ◽  
In Situ Observation ◽  
Observation Data ◽  
The Tibetan Plateau

Abstract. The Tibetan Plateau is a critical region in the research of biosphere-atmosphere interactions on both regional and global scales due to its relation to Asian summer monsoon and El Niño. The unique environment on the Plateau provides valuable information for the evaluation of the models' surface energy partitioning associated with the summer monsoon. In this study, we investigated the surface energy partitioning on this important area through comparative analysis of two biosphere models constrained by the in-situ observation data. Indeed, the characteristics of the Plateau provide a unique opportunity to clarify the structural deficiencies of biosphere models as well as new insight into the surface energy partitioning on the Plateau. Our analysis showed that the observed inconsistency between the two biosphere models was mainly related to: 1) the parameterization for soil evaporation; 2) the way to deal with roughness lengths of momentum and scalars; and 3) the parameterization of subgrid velocity scale for aerodynamic conductance. Our study demonstrates that one should carefully interpret the modeling results on the Plateau especially during the pre-monsoon period.

Late Eocene post-collisional magmatic rocks from the southern Qiangtang terrane record the melting of pre-collisional enriched lithospheric mantle

2021 ◽  
Author(s):  
Yue Qi ◽  
Qiang Wang ◽  
Gang-jian Wei ◽  
Xiu-Zheng Zhang ◽  
Wei Dan ◽  
...  
Keyword(s):  
Tibetan Plateau ◽  
Trace Element ◽  
Partial Melting ◽  
Early Cretaceous ◽  
Lithospheric Mantle ◽  
Late Eocene ◽  
The Tibetan Plateau ◽  
Mafic Rocks ◽  
Isotopic Compositions ◽  
Qiangtang Terrane

Diverse rock types and contrasting geochemical compositions of post-collisional mafic rocks across the Tibetan Plateau indicate that the underlying enriched lithospheric mantle is heterogeneous; however, how these enriched mantle sources were formed is still debated. The accreted terranes within the Tibetan Plateau experienced multiple stages of evolution. To track the geochemical characteristics of their associated lithospheric mantle through time, we can use mantle-derived magmas to constrain the mechanism of mantle enrichment. We report zircon U-Pb ages, major and trace element contents, and Sr-Nd isotopic compositions for Early Cretaceous and late Eocene mafic rocks in the southern Qiangtang terrane. The Early Cretaceous Baishagang basalts (107.3 Ma) are characterized by low K2O/Na2O (<1.0) ratios, arc-like trace element patterns, and uniform Sr-Nd isotopic compositions [(87Sr/86Sr)i = 0.7067−0.7073, εNd(t) = −0.4 to −0.2]. We suggest that the Baishagang basalts were derived from partial melting of enriched lithospheric mantle that was metasomatized by subducted Bangong−Nujiang oceanic material. We establish the geochemistry of the pre-collisional enriched lithospheric mantle under the southern Qiangtang terrane by combining our data with those from other Early Cretaceous mafic rocks in the region. The late Eocene (ca. 35 Ma) post-collisional rocks in the southern Qiangtang terrane have low K2O/Na2O (<1.0) ratios, and their major element, trace element, and Sr-Nd isotopic compositions [(87Sr/86Sr)i = 0.7042−0.7072, εNd(t) = −4.5 to +1.5] are similar to those of the Early Cretaceous mafic rocks. Based on the distribution, melting depths, and whole-rock geochemical compositions of the Early Cretaceous and late Eocene mafic rocks, we argue that the primitive late Eocene post-collisional rocks were derived from pre-collisional enriched lithospheric mantle, and the evolved samples were produced by assimilation and fractional crystallization of primary basaltic magma. Asthenosphere upwelling in response to the removal of lithospheric mantle induced the partial melting of enriched lithospheric mantle at ca. 35 Ma.

scholarly journals Observational evidence of particle hygroscopic growth in the upper troposphere–lower stratosphere (UTLS) over the Tibetan Plateau

2019 ◽  
Vol 19 (13) ◽  
pp. 8399-8406 ◽  
Author(s):  
Qianshan He ◽  
Jianzhong Ma ◽  
Xiangdong Zheng ◽  
Xiaolu Yan ◽  
Holger Vömel ◽  
...  
Keyword(s):  
Relative Humidity ◽  
Tibetan Plateau ◽  
Lower Stratosphere ◽  
Fine Particles ◽  
Asian Summer Monsoon ◽  
Radiative Properties ◽  
Aerosol Layer ◽  
The Tibetan Plateau ◽  
Hygroscopic Growth ◽  
Upper Troposphere

Abstract. We measured the vertical profiles of backscatter ratio (BSR) using the balloon-borne, lightweight Compact Optical Backscatter AerosoL Detector (COBALD) instruments above Linzhi, located in the southeastern Tibetan Plateau, in the summer of 2014. An enhanced aerosol layer in the upper troposphere–lower stratosphere (UTLS), with BSR (455 nm) > 1.1 and BSR (940 nm) > 1.4, was observed. The color index (CI) of the enhanced aerosol layer, defined as the ratio of aerosol backscatter ratios (ABSRs) at wavelengths of 940 and 455 nm, varied from 4 to 8, indicating the prevalence of fine particles with a mode radius of less than 0.1 µm. We find that unlike the very small particles (mode radius smaller than 0.04 µm) at low relative humidity (RHi < 40 %), the relatively large particles in the aerosol layer were generally very hydrophilic as their size increased dramatically with relative humidity. This result indicates that water vapor can play a very important role in increasing the size of fine particles in the UTLS over the Tibetan Plateau. Our observations provide observation-based evidence supporting the idea that aerosol particle hygroscopic growth is an important factor influencing the radiative properties of the Asian Tropopause Aerosol Layer (ATAL) during the Asian summer monsoon.

scholarly journals Air moisture signals in a stable oxygen isotope chronology of dwarf shrubs from the central Tibetan Plateau

2019 ◽  
Vol 124 (1) ◽  
pp. 53-64
Author(s):  
Jakob Wernicke ◽  
Georg Stark ◽  
Lily Wang ◽  
Jussi Grießinger ◽  
Achim Bräuning
Keyword(s):  
Tibetan Plateau ◽  
Tree Ring ◽  
Growth Ring ◽  
Asian Summer Monsoon ◽  
Monsoon Circulation ◽  
Nam Co ◽  
Climate Signal ◽  
Dwarf Shrubs ◽  
Central Tibetan Plateau ◽  
Annual Growth Rings

Abstract Background and Aims Annually resolved biological climate proxies beyond the altitudinal and latitudinal distribution limit of trees are rare. In such regions, several studies have demonstrated that annual growth rings of dwarf shrubs are suitable proxies for palaeoclimatic investigations. In High Asia, the pioneer work of Liang et al. (Liang E, Lu X, Ren P, Li X, Zhu L, Eckstein D, 2012. Annual increments of juniper dwarf shrubs above the tree line on the central Tibetan Plateau: a useful climatic proxy. Annals of Botany109: 721–728) confirmed the suitability of shrub growth-ring chronologies for palaeoclimatic research. This study presents the first sensitivity study of an annually resolved δ18O time series inferred from Wilson juniper (Juniperus pingii var. wilsonii) from the northern shoreline of lake Nam Co (Tibetan Plateau). Methods Based on five individual dwarf shrub discs, a statistically reliable δ18O chronology covering the period 1957–2009 was achieved (expressed population signal = 0.80). Spearman’s correlation analysis between the δ18O chronology and climate variables from different sources was applied. In a first step, the suitability of various climate data was evaluated. Key Results Examinations of climate–proxy relationships revealed significant negative correlations between the δ18O shrub chronology and summer season moisture variability of the previous and current year. In particular, relative humidity of the previous and current vegetation period significantly determined the proxy variability (ρ = −0.48, P < 0.01). Furthermore, the δ18O variability of the developed shrub chronology significantly coincided with a nearby tree-ring δ18O chronology of the same genus (r = 0.62, P < 0.01). Conclusions The δ18O shrub chronology reliably recorded humidity variations in the Nam Co region. The chronology was significantly correlated with a nearby moisture-sensitive tree-ring δ18O chronology, indicating a common climate signal in the two chronologies. This climate signal was likely determined by moisture variations of the Asian summer monsoon. Local climate effects were superimposed on the supra-regional climate signature of the monsoon circulation. Opposing δ18O values between the two chronologies were interpreted as plant-physiological differences during isotopic fractionation processes.

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