| Citation: |
Zhong-bao Zhao, Chao Li, Xu-xuan Ma, 2021. How does the elevation changing response to crustal thickening process in the central Tibetan Plateau since 120 Ma?, China Geology, 4, 32-43. doi: 10.31035/cg2021013
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How does the elevation changing response to crustal thickening process in the central Tibetan Plateau since 120 Ma?
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Abstract
When and how the Tibetan Plateau formed and maintained its thick crust and high elevation on Earth is continuing debated. Specifically, the coupling relationship between crustal thickening and corresponding paleoelevation changing has not been well studied. The dominant factors in crustal thickness changing are crustal shortening, magmatic input and surface erosion rates. Crustal thickness change and corresponding paleoelevation variation with time were further linked by an isostatic equation in this study. Since 120 Ma crustal shortening, magmatic input and surface erosion rates data from the central Tibetan Plateau are took as input parameters. By using a one-dimensional isostasy model, the authors captured the first-order relationship between crustal thickening and historical elevation responses over the central Tibetan Plateau, including the Qiangtang and Lhasa terranes. Based on the modeling results, the authors primarily concluded that the Qiangtang terrane crust gradually thickened to ca. 63 km at ca. 40 Ma, mainly due to tectonic shortening and minor magmatic input combined with a slow erosion rate. However, the Lhasa terrane crust thickened by a combination of tectonic shortening, extensive magmatic input and probably Indian plate underthrusting, which thickened the Lhasa crust over 75 km since 25 Ma. Moreover, a long-standing elevation >4000 m was strongly coupled with a thickened crust since about 35 Ma in the central Tibetan Plateau.
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Keywords:
- Crustal thickness /
- Paleoelevation /
- Isostatic modeling /
- Qiangtang terrane /
- Lhasa terrane /
- Tibetan Plateau /
- China
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References
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Zhong-bao Zhao, Chao Li, Xu-xuan Ma, 2021. How does the elevation changing response to crustal thickening process in the central Tibetan Plateau since 120 Ma?, China Geology, 4, 32-43. doi: 10.31035/cg2021013
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Figure 1.
Elevation map of the Tibetan Plateau with main tectonic units and their boundaries. Elevation data were downloaded from http://www2.jpl.nasa.gov/srtm/. Locations of the collected data are shown, and more information is in their
supplementary Tables S1 –S5 . JSS–Jinsha suture; LSS–Longmu Co-Shuanghu suture; BNS–Bangong-Nujiang suture; IYS–Indus-Yarlung suture. -
Figure 2.
Collected and reprocessed data of geological observations are shown. The best fit modeled results are illustrated by curves. a–timing of two major episodes during tectonic deformation for the Lhasa and Qiangtang terranes (see
supplementary Table S3 ). b, c–magmatic input flux rates estimates for the Lhasa and Qiangtang terranes, respectively (Fig. 4;supplementary Table S1 ). Blue and red lines are obtained from modeling results which are used to compare with calculated line. Green line is cited from Ma XX et al. (2021) which is statics of documented magma ages on the Lhasa terrane. d–geological constraints for crustal thickness in the Lhasa and Qiangtang terranes (see Zhu DC et al., 2017 andsupplementary Table S2 ). e–geological constraints for paleoelevation. f–in this figure, red and blue crosses show the collected results for the Lhasa and Qiangtang terranes, respectively. The blue and red curves show the results of the reference simulation for the Qiangtang and Lhasa terranes, respectively. Crosses show the geological constraints for erosion rates. -
Figure 3.
Magmatism contoured by geological time, scale from 85ºE to 90ºE in the Qiangtang and Lhasa terranes. Abbreviations are same as Fig. 1.
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Figure 4.
Magmatic input flux estimates for the Lhasa and Qiangtang terranes, respectively (data are shown in the
supplementary Table S1 ). Gray histograms show the pluton-exposed area, and the black squares show magmatic influx rates. -
Figure 5.
The crustal thickness variation of the southern Qiangtang terrane from 170 Ma to 55 Ma. The crustal thickness variation of the southern Qiangtang terrane was based on data from
supplementary Table S2 . Different colors means collected from different literatures. -
Figure 6.
Results of Set 1–2 simulations. a-1 and b-1 represent crustal thickness; a-2 and b-2 represent total thickness, here, total thickness is equal to crustal thickness plus crustal root thickness; a-3 and b-3 represent simulated elevation; and a-4 and b-4 represent the magmatic thickening rates and erosion rates. The Set 1 simulation indicates the lowest and final paleoelevation of the Qiangtang terrane, with a crustal density equal to 2.8×103 kg/m3. Set 2 is the best fit simulation for the Qiangtang terrane when the crustal density is decreasing to 2.6×103 kg/m3.
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Figure 7.
Results of Set 3–4 simulations. a-1 and b-1 represent crustal thickness; a-2 and b-2 represent total thickness, here, total thickness is equal to crustal thickness plus crustal root thickness; a-3 and b-3 represent simulated elevation; and a-4 and b-4 represent the magmatic thickening rates and erosion rates. The Set 3 model does not consider the underthrusting of the Indian Plate beneath the Lhasa terrane. Set 4 is the best fit simulation for the Lhasa terrane after adding an additional ca. 10 km crustal thickness.