Propagation of surface uplift, lower crustal flow, and Cenozoic tectonics of the southeast margin of the Tibetan Plateau

Geology ◽  
2006 ◽  
Vol 34 (10) ◽  
pp. 813 ◽  
Author(s):  
Lindsay M. Schoenbohm ◽  
B. Clark Burchfiel ◽  
Chen Liangzhong
Keyword(s):  
Tibetan Plateau ◽  
The Tibetan Plateau ◽  
Surface Uplift ◽  
Cenozoic Tectonics ◽  
Lower Crustal Flow ◽  
Lower Crustal

The Mechanism and Dynamics of N-S trends normal faults in Tibetan Plateau: Insight From Thermochronology, Magnetotellurics, Magmatism and GPS Measurements

2020 ◽  
Author(s):  
Han-Ao Li ◽  
in-Gen Dai ◽  
Le-Tian Zhang ◽  
Ya-Lin Li ◽  
Guang-Hao Ha ◽  
...  
Keyword(s):  
Tibetan Plateau ◽  
Lower Crust ◽  
Normal Faults ◽  
The Tibetan Plateau ◽  
Gps Measurements ◽  
Southern Tibet ◽  
Magnetotelluric Data ◽  
Deep Process ◽  
Lower Crustal Flow ◽  
Lower Crustal

<p>The N-S trends normal faults are widespread through the whole Tibetan Plateau. It records key information for the growth and uplift of the Tibetan Plateau. Numerous models are provided to explain the causes of rifting in the Tibetan Plateau based on the low-temperature thermochronology<sup>1</sup>. With the developments of the geophysical and magmatic geochemistry methods and its applications on the Tibetan Plateau, we could gain more profound understanding on the sphere structure of the Tibetan Plateau. This would give us more clues on how the deep process affect the formation and evolution of the shallow normal faults. However, few researchers pay attention on this and the relationship between the surface evolution and deep process of these faults. In order to solve these puzzles, we collected the published thermochronology data, magnetotelluric data, faults-related ultrapotassic, potassic and the adakitic rocks ages and present-day GPS measurements. We find that the distribution of the N-S trends normal faults are closely related to the weak zones in the middle to lower crust (15-50 km) revealed by the magmatism and magnetotelluric data<sup>2</sup>. Besides, the present-day GPS data show that the E-W extension rates match well with the eastward movements speeds interior Tibetan Plateau<sup>3</sup>. Combined with the thermochronology data (25-4 Ma), we concluded that 1.The weak zone in the middle to lower crust influence the developments and evolution of the N-S trends normal faults. 2. The material eastward flow enhance the N-S normal faults developments. 3. The timing of the middle to lower crustal flow may begin in the Miocene.</p><p><strong>Key words:</strong> N-S trends normal faults; Thermochronology; Magnetotellurics; Magmatism; GPS Measurements; middle to lower crustal flow</p><p><strong>References:</strong></p><p><sup>1</sup>Lee, J., Hager, C., Wallis, S.R., Stockli, D.F., Whitehouse, M.J., Aoya, M. and Wang, Y., 2011. Middle to Late Miocene Extremely Rapid Exhumation and Thermal Reequilibration in the Kung Co Rift, Southern Tibet. Tectonics, 30(2).</p><p><sup>2</sup>Pang, Y., Zhang, H., Gerya, T.V., Liao, J., Cheng, H. and Shi, Y., 2018. The Mechanism and Dynamics of N-S Rifting in Southern Tibet: Insight from 3-D Thermomechanical Modeling. Journal of Geophysical Research: Solid Earth.</p><p><sup>3</sup>Zhang, P.-Z., Shen, Z., Wang, M., Gan, W., Bürgmann, R., Molnar, P., Wang, Q., Niu, Z., Sun, J., Wu, J., Hanrong, S. and Xinzhao, Y., 2004. Continuous Deformation of the Tibetan Plateau from Global Positioning System Data. Geology, 32(9).</p><p><strong>Acknowledgements:</strong></p><p>We thank Shi-Ying Xu, Xu Han, Bo-Rong Liu for collecting data. Special thanks are given to Dr. Guang-Hao Ha and Professors Jin-Gen Dai, Le-Tian Zhang，Ya-Lin Li and Cheng-Shan Wang for many critical and constructive comments.</p>

scholarly journals Cenozoic shortening budget for the northeastern edge of the Tibetan Plateau: Is lower crustal flow necessary?

Tectonics ◽  
2012 ◽  
Vol 31 (3) ◽  
pp. n/a-n/a ◽  
Author(s):  
Richard O. Lease ◽  
Douglas W. Burbank ◽  
Huiping Zhang ◽  
Jianhui Liu ◽  
Daoyang Yuan
Keyword(s):  
Tibetan Plateau ◽  
The Tibetan Plateau ◽  
Lower Crustal Flow ◽  
Lower Crustal

Geochemical and isotopic data of Zheduo-Gongga granitic intrusive complex, eastern margin of the Tibetan Plateau: no evidence for middle-lower crustal flow

2020 ◽  
Author(s):  
Fangyang Hu ◽  
Fuyuan Wu ◽  
Mihai Ducea ◽  
James Chapman
Keyword(s):  
Tibetan Plateau ◽  
Partial Melting ◽  
Lower Crust ◽  
Biotite Granite ◽  
The Tibetan Plateau ◽  
Eastern Margin ◽  
Granitoid Rocks ◽  
Lower Crustal Flow ◽  
Group 2 ◽  
Lower Crustal

<p>Geophysical studies have shown that middle-lower crustal flow started from central Tibetan Plateau may exist in the eastern margin of the Tibetan Plateau, which controls the mountain building, crustal thickening and deformation (Schoenbohm et al., 2006; Bai et al., 2010; Bao et al., 2015; Zhu et al., 2017). However, no geological and petrological evidence have been presented. We carried out detailed studies on the geochemical and isotopic compositions of the Mesozoic-Cenozoic Zheduo-Gongga granitic intrusive complex on the eastern margin of the Tibet Plateau. Geochronology studies show that these granitoid rocks are formed during Mesozoic to Cenozoic, including ~220-200 Ma Gongga granodiorite to biotite granite with mafic enclaves, ~40 Ma Zheduo gneissic granite, ~28 Ma Zheduo monzogranite, and ~20-4 Ma Zheduo biotite granite and monzogranite. Two groups of geochemical features are obtained: Group 1 (gnessic granite, granodiorite, monzogranite, and leucogranite) has relatively low K2O, Th/La, La/Yb and Rb/Sr ratios, but high Sr/Y ratio with no Eu negative anomalies; Group 2 (biotite granite) has relatively high K2O, Th/La, La/Yb and Rb/Sr ratios, but low Sr/Y with strong negative Eu anomalies. The Sr-Nd-Hf-O isotopic studies on plagioclase, apatite and zircon show that their sources are primarily the basement of the western margin of Yangtze Craton and Songpan-Ganzi sediments. These features indicate that they have different petrogenesis processes. Group 1 is mainly derived from partial melting of mafic rocks in the lower crust, whereas the Group 2 is primarily derived from partial melting of metasedimentary rocks experiencing fractionation of plagioclase. Magma derived from different sources mixing with each other are observed as well. Therefore, from geochemical aspects, no exotic materials are involved in the formation of granitoid rocks during Mesozoic to present. The flow of crustal material in the middle-lower crust may be not existed. The low velocity and high conductivity layer in the middle-lower crust may represent a regional partial melting zone, which could be related to the upwelling of asthenosphere. Both crustal deformation and upwelling of asthenosphere may contribute to the crustal thicknening and uplift.</p>

scholarly journals Linking deeply-sourced volatile emissions to plateau growth dynamics in southeastern Tibetan Plateau

2021 ◽  
Vol 12 (1) ◽  
Author(s):  
Maoliang Zhang ◽  
Zhengfu Guo ◽  
Sheng Xu ◽  
Peter H. Barry ◽  
Yuji Sano ◽  
...  
Keyword(s):  
Tibetan Plateau ◽  
Growth Dynamics ◽  
High Elevation ◽  
Fault System ◽  
The Tibetan Plateau ◽  
Southeastern Tibetan Plateau ◽  
Surface Uplift ◽  
Multi Stage ◽  
Geodynamic Processes ◽  
Underlying Mechanisms

AbstractThe episodic growth of high-elevation orogenic plateaux is controlled by a series of geodynamic processes. However, determining the underlying mechanisms that drive plateau growth dynamics over geological history and constraining the depths at which growth originates, remains challenging. Here we present He-CO2-N2 systematics of hydrothermal fluids that reveal the existence of a lithospheric-scale fault system in the southeastern Tibetan Plateau, whereby multi-stage plateau growth occurred in the geological past and continues to the present. He isotopes provide unambiguous evidence for the involvement of mantle-scale dynamics in lateral expansion and localized surface uplift of the Tibetan Plateau. The excellent correlation between 3He/4He values and strain rates, along the strike of Indian indentation into Asia, suggests non-uniform distribution of stresses between the plateau boundary and interior, which modulate southeastward growth of the Tibetan Plateau within the context of India-Asia convergence. Our results demonstrate that deeply-sourced volatile geochemistry can be used to constrain deep dynamic processes involved in orogenic plateau growth.

scholarly journals The Role of Lower Crustal Rheology in Lithospheric Delamination During Orogeny

2021 ◽  
Vol 9 ◽  
Author(s):  
Lin Chen
Keyword(s):  
Lower Crust ◽  
Numerical Models ◽  
The Tibetan Plateau ◽  
Mantle Lithosphere ◽  
Laboratory Studies ◽  
Surface Uplift ◽  
Continental Lower Crust ◽  
Lower Crustal ◽  
Flow Laws

The continental lower crust is an important composition- and strength-jump layer in the lithosphere. Laboratory studies show its strength varies greatly due to a wide variety of composition. How the lower crust rheology influences the collisional orogeny remains poorly understood. Here I investigate the role of the lower crust rheology in the evolution of an orogen subject to horizontal shortening using 2D numerical models. A range of lower crustal flow laws from laboratory studies are tested to examine their effects on the styles of the accommodation of convergence. Three distinct styles are observed: 1) downwelling and subsequent delamination of orogen lithosphere mantle as a coherent slab; 2) localized thickening of orogen lithosphere; and 3) underthrusting of peripheral strong lithospheres below the orogen. Delamination occurs only if the orogen lower crust rheology is represented by the weak end-member of flow laws. The delamination is followed by partial melting of the lower crust and punctuated surface uplift confined to the orogen central region. For a moderately or extremely strong orogen lower crust, topography highs only develop on both sides of the orogen. In the Tibetan plateau, the crust has been doubly thickened but the underlying mantle lithosphere is highly heterogeneous. I suggest that the subvertical high-velocity mantle structures, as observed in southern and western Tibet, may exemplify localized delamination of the mantle lithosphere due to rheological weakening of the Tibetan lower crust.

Miocene Olivine Leucitites in the Hoh Xil Basin, Northern Tibet: Implications for Intracontinental Lithosphere Melting and Surface Uplift of the Tibetan Plateau

2020 ◽  
Vol 61 (1) ◽  
Author(s):  
Yue Qi ◽  
Qiang Wang ◽  
Ying-Tang Zhu ◽  
Lian-Chang Shi ◽  
Ya-Nan Yang
Keyword(s):  
Tibetan Plateau ◽  
Lithospheric Mantle ◽  
The Tibetan Plateau ◽  
Nd Isotope ◽  
Northern Tibet ◽  
Surface Uplift ◽  
Enriched Mantle ◽  
Magmatic Rocks ◽  
Low Degree ◽  
Pliocene Magmatism

Abstract The generation of Miocene–Pliocene post-collisional magmatic rocks in northern Tibet was coeval with surface uplift, meaning that understanding the petrogenesis of these rocks should provide clues to the mechanism of uplift of the Tibetan Plateau. However, the nature of the source(s) of Miocene–Pliocene post-collisional rocks is unresolved, especially for potassic–ultrapotassic rocks. This study focuses on 16 Ma olivine leucitites in the Hoh Xil Basin of northern Tibet, which display the lowest SiO2 (43·4–48·8 wt%) contents of all Miocene–Pliocene magmatic rocks in northern Tibet and have high MgO (4·85–8·57 wt%) contents and high K2O/Na2O (>1) ratios. Whole-rock geochemical compositions suggest that the olivine leucitites did not undergo significant fractional crystallization or crustal assimilation. All samples are enriched in large ion lithophile elements relative to high field strength elements, and they exhibit uniform whole-rock Sr–Nd isotope [(87Sr/86Sr)i = 0·7071–0·7077 and εNd(t) = −3·1 to −3·9] and olivine O isotope (5·8–6·6 ‰, mean of 6·2 ± 0·2 ‰, n = 21) compositions. We propose that the olivine leucitites were derived by low-degree partial melting of phlogopite-lherzolite in garnet-facies lithospheric mantle. Given the tectonic evolution of the Hoh Xil Basin and adjacent areas, we suggest that southward subduction of Asian (Qaidam block) lithosphere after India–Asia collision transferred potassium and other incompatible elements into the lithospheric mantle, forming the K-enriched mantle source of the Miocene–Pliocene potassic–ultrapotassic rocks. Removal of lower lithospheric mantle subsequently induced voluminous Miocene–Pliocene magmatism and generated >1 km surface uplift in the Hoh Xil Basin.

Early Cenozoic Tectonics of the Tibetan Plateau

2013 ◽  
Vol 87 (2) ◽  
pp. 289-303 ◽  
Author(s):  
WU Zhenhan ◽  
HU Daogong ◽  
YE Peisheng ◽  
WU Zhonghai
Keyword(s):  
Tibetan Plateau ◽  
The Tibetan Plateau ◽  
Cenozoic Tectonics ◽  
Early Cenozoic
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