3-d finite element modeling of the rise and fall of the himalayan-tibetan plateau mian liu and...
TRANSCRIPT
![Page 1: 3-D Finite Element Modeling of the Rise and Fall of the Himalayan-Tibetan Plateau Mian Liu and Youqing Yang Dept. of Geological Sciences, University of](https://reader038.vdocuments.us/reader038/viewer/2022110320/56649cc05503460f94986e63/html5/thumbnails/1.jpg)
3-D Finite Element Modeling of the Rise and Fall of the Himalayan-Tibetan Plateau
Mian Liu and Youqing Yang
Dept. of Geological Sciences, University of Missouri-Columbia
![Page 2: 3-D Finite Element Modeling of the Rise and Fall of the Himalayan-Tibetan Plateau Mian Liu and Youqing Yang Dept. of Geological Sciences, University of](https://reader038.vdocuments.us/reader038/viewer/2022110320/56649cc05503460f94986e63/html5/thumbnails/2.jpg)
Some of the fundamental questions of the Tibetan tectonics
• What causes the E-W extension in Tibet? When did the “collapse” start?
• When did the Tibetan plateau uplift? What are the temporal and spatial evolution of the mountain building in Tibet?
• How was the >2000 km crustal shortening accommodated? What controlled the strain partitioning between crustal thickening and lateral extrusion?
![Page 3: 3-D Finite Element Modeling of the Rise and Fall of the Himalayan-Tibetan Plateau Mian Liu and Youqing Yang Dept. of Geological Sciences, University of](https://reader038.vdocuments.us/reader038/viewer/2022110320/56649cc05503460f94986e63/html5/thumbnails/3.jpg)
GPS velocity relative to stable Siberia
Data from Larson et al., 1999; Chen et al., 2000; Wang et al., 2001
Earthquake focal mechanismshowing E-W extension
Data from Harvard Catalog
![Page 4: 3-D Finite Element Modeling of the Rise and Fall of the Himalayan-Tibetan Plateau Mian Liu and Youqing Yang Dept. of Geological Sciences, University of](https://reader038.vdocuments.us/reader038/viewer/2022110320/56649cc05503460f94986e63/html5/thumbnails/4.jpg)
Active crustal deformation in Tibet:3-D finite element model & rheology
![Page 5: 3-D Finite Element Modeling of the Rise and Fall of the Himalayan-Tibetan Plateau Mian Liu and Youqing Yang Dept. of Geological Sciences, University of](https://reader038.vdocuments.us/reader038/viewer/2022110320/56649cc05503460f94986e63/html5/thumbnails/5.jpg)
Crustal StressIndicated byEarthquake Data
Predicted Stress State in the upper crust
![Page 6: 3-D Finite Element Modeling of the Rise and Fall of the Himalayan-Tibetan Plateau Mian Liu and Youqing Yang Dept. of Geological Sciences, University of](https://reader038.vdocuments.us/reader038/viewer/2022110320/56649cc05503460f94986e63/html5/thumbnails/6.jpg)
Elevation reduced to 50% of present values
No E-W extension predicted
Basal shear = 30 MPa under Himalayas and south Tibet
A narrow zone of nearly N-SExtension – South Tibetan Detachment Fault system?
![Page 7: 3-D Finite Element Modeling of the Rise and Fall of the Himalayan-Tibetan Plateau Mian Liu and Youqing Yang Dept. of Geological Sciences, University of](https://reader038.vdocuments.us/reader038/viewer/2022110320/56649cc05503460f94986e63/html5/thumbnails/7.jpg)
Long-term history of the Himalayan-Tibetan orogen
Viscous thin-sheet model
(England & Houseman, 1986)
Plasticine analog model
(Tapponnier et al., 1986)
![Page 8: 3-D Finite Element Modeling of the Rise and Fall of the Himalayan-Tibetan Plateau Mian Liu and Youqing Yang Dept. of Geological Sciences, University of](https://reader038.vdocuments.us/reader038/viewer/2022110320/56649cc05503460f94986e63/html5/thumbnails/8.jpg)
3-D finite strain model
x10 vertical exaggeration
Indian plate
Tarim
Sich
uan
BasinAsia
![Page 9: 3-D Finite Element Modeling of the Rise and Fall of the Himalayan-Tibetan Plateau Mian Liu and Youqing Yang Dept. of Geological Sciences, University of](https://reader038.vdocuments.us/reader038/viewer/2022110320/56649cc05503460f94986e63/html5/thumbnails/9.jpg)
![Page 10: 3-D Finite Element Modeling of the Rise and Fall of the Himalayan-Tibetan Plateau Mian Liu and Youqing Yang Dept. of Geological Sciences, University of](https://reader038.vdocuments.us/reader038/viewer/2022110320/56649cc05503460f94986e63/html5/thumbnails/10.jpg)
40 Ma
20 Ma Present
10 Ma
![Page 11: 3-D Finite Element Modeling of the Rise and Fall of the Himalayan-Tibetan Plateau Mian Liu and Youqing Yang Dept. of Geological Sciences, University of](https://reader038.vdocuments.us/reader038/viewer/2022110320/56649cc05503460f94986e63/html5/thumbnails/11.jpg)
Near surface velocity
Because of the depth-variable lithospheric rheology, the surface velocity can be significantly different from that in the lower crust.
![Page 12: 3-D Finite Element Modeling of the Rise and Fall of the Himalayan-Tibetan Plateau Mian Liu and Youqing Yang Dept. of Geological Sciences, University of](https://reader038.vdocuments.us/reader038/viewer/2022110320/56649cc05503460f94986e63/html5/thumbnails/12.jpg)
The predicted plateau formation is sensitive to the lower crustal rheology
Lower crustal viscosity 2.5 times higher than the base model
Lower crustal viscosity 0.5 times the base model value
![Page 13: 3-D Finite Element Modeling of the Rise and Fall of the Himalayan-Tibetan Plateau Mian Liu and Youqing Yang Dept. of Geological Sciences, University of](https://reader038.vdocuments.us/reader038/viewer/2022110320/56649cc05503460f94986e63/html5/thumbnails/13.jpg)
Predicted uplift history of the different parts of the Tibetan Plateau
Accelerated uplift but different history at various parts of Tibet; Most parts reached >3 km ~10-20 Myr ago.
![Page 14: 3-D Finite Element Modeling of the Rise and Fall of the Himalayan-Tibetan Plateau Mian Liu and Youqing Yang Dept. of Geological Sciences, University of](https://reader038.vdocuments.us/reader038/viewer/2022110320/56649cc05503460f94986e63/html5/thumbnails/14.jpg)
Predicted Crustal Mass Distribution
![Page 15: 3-D Finite Element Modeling of the Rise and Fall of the Himalayan-Tibetan Plateau Mian Liu and Youqing Yang Dept. of Geological Sciences, University of](https://reader038.vdocuments.us/reader038/viewer/2022110320/56649cc05503460f94986e63/html5/thumbnails/15.jpg)
Conclusions• The E-W extension in Tibet can be explained by gravitational
collapse of the plateau. Major E-W extension started only when the plateau reached ~75% of its present values.
• Assuming a flat Asian continent before the Indo-Asian collision, the plateau would have grown from S to N, and from W to E; most part of the plateau probably reached >3 km 10-20 million years ago.
• The lower crust flow largely controls the topographic evolution; the motion of the upper crust may be significantly different from that in the lower crust.
• Partitioning of the shortened crustal mass between thickening and lateral extrusion/erosion changed with time. Mass accommodated by mountain building may have peaked ~10 Myr ago; extrusion and erosion become increasingly important.