# Finite Element Modeling of Extensional Structures in the Annapurna Region of Central Himalayas

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## Abstract

Two-dimensional, elastic, plane-strain, finite element model are generated to investigate the extensional structures mainly normal fault in the Annapurna region, central Himalaya. The numerical study was performed on the Miocene geologic profile considering both of the convergent displacement and rock layer properties in the regime. Results show that the normal fault primarily influenced by model geometry, rheology (layer properties) and boundary condition (applied convergence displacement). Simulated normal fault density exhibits very high intensity in Lesser Himalaya then in the Tethys Himalaya and low intensity in the Higher Himalaya, suggesting the vulnerability of fault development to low-grade metamorphic rock than the high-grade rocks. The location of normal fault predicted by the numerical model analysis is consistent to the position of normal fault segments by Kaneko (J Geol Soc Jpn 103(3):203–226, 1997). In this studies, it also believed that the presence of these normal faults and underthrusting of the sub-Himalayan sequence with associated tectonic forces, the Himalayan Metamorphic belt has been exhumed and differentially domal uplifted and then segmented into several blocks.

## Keywords

Himalaya Finite element method Extensional structures Tectonics## Notes

### Acknowledgments

M. Farhad Howladar is thankful to Prof. D. Hayashi, University of the Ryukyus, Okinawa, Japan for helping to construct this finite element model. Author also equally thankful to Prof. M. Ahmed and two reviewers for their critical comments, suggestion and modifications which improved this research greatly. M. Farhad Howladar has been supported financially for this research by Heiwa Nakajima Foundation, Tokyo, Japan.

## References

- Anderson EM (1951) The dynamics of faulting and dyke formation with applications to Britain, 1st edn. Oliver and Boyd, Edinburg, p 206Google Scholar
- Brodet P, Colchen M, Le Fort P (1972) Some features of the geology of the Annapurna range, Nepal Himalaya. Himal Geol 2:537–563Google Scholar
- Brunel M (1986) Ductile thrusting in the Himalayas: shear sense criteria and stretching lineations. Tectonics 5:247–265. doi: 10.1029/TC005i002p00247 CrossRefGoogle Scholar
- Cattin R, Avouac JP (2000) Modeling mountain building and the seismic cycle in the Himalaya of Nepal. J Geophys Res 105(B6):13389–13407. doi: 10.1029/2000JB900032 CrossRefGoogle Scholar
- Chemenda A, Mattauer M, Malavieille J, Bokun AN (1995) A mechanism of syn-collisional deep rock exhumation and associated normal faulting: results from physical modeling. Earth Planet Sci Lett 132:225–232. doi: 10.1016/0012-821X(95)00042-B CrossRefGoogle Scholar
- Chemenda A, Burg JP, Mattauer M (2000) Evolutionary model of the Himalaya-Tibet system: Geo-poem based on new modeling, geological and geophysical data. Earth Planet Sci Lett 174:397–409. doi: 10.1016/S0012-821X(99)00277-0 CrossRefGoogle Scholar
- Clough RW (1960) The finite element method in plane stress analysis. In: Am Soc Civil Engrs, Proceedings 2nd conference. On electronic computation, Pittsburg, PennGoogle Scholar
- DeCelles PG, Gehrels GE, Quade J, LaReau B, Spurlin M (2000) Tectonic implications of U–Pb zircon ages of the Himalayan orogenic belt in Nepal. Science 288:497–499. doi: 10.1126/science.288.5465.497 CrossRefGoogle Scholar
- DeCelles PG, Robinson DM, Quade J, Copeland P, Upreti BN, Ojha TP, Garzione CN (2001) Regional structure and stratigraphy of the Himalayan fold-thrust belt, far western Nepal. Tectonics 20:487–509. doi: 10.1029/2000TC001226 CrossRefGoogle Scholar
- Dèzes P (1999) Tectonic and metamorphic evolution of the central Himalayan domain in southeast Zanskar (Kashmir, India). Mémoires de Géologie (Lausanne) 32:149Google Scholar
- England PC, Thompson A (1984) Pressure-temperature-time paths of regional metamorphism, part 1: heat transferring the evolution of regions of the thickened continental crust. J Petrol 25:929–954Google Scholar
- Guillot S (1999) An overview of the metamorphic evolution in central Nepal. J Asian Earth Sci 17:713–725. doi: 10.1016/S1367-9120(99)00045-0 CrossRefGoogle Scholar
- Harrison TM, Grove M, Lovera OM, Catlos EJ (1998) A model for the origin of Himalayan anatexis and inverted metamorphism. J Geophys Res 103:27017–27032. doi: 10.1029/98JB02468 CrossRefGoogle Scholar
- Howladar MF, Hayashi D (2003) Numerical fault simulation in the Himalaya with 2 D finite element method. J Polar Geosci 16:243–257Google Scholar
- Kaneko Y (1995) Thermal structure in the Annapurna region, central Nepal Himalaya: implication for the inverted metamorphism. J Miner Petrol Econ Geol 90:143–154. doi: 10.2465/ganko.90.143 CrossRefGoogle Scholar
- Kaneko Y (1997) Two-step exhumation model of the Himalayan metamorphic Belt, central Nepal. J Geol Soc Jpn 103(3):203–226Google Scholar
- Kündig R (1988) Crystallization and deformation in Higher Himalaya, Zankar (NW-India): ETH Zurich, p 188Google Scholar
- Le Fort P (1975) Himalayas: the collide range, present knowledge of the continental arc. Am J Sci 275:1–44Google Scholar
- Lyon-Caen H, Molnar P (1983) Constraints on the structure of the Himalaya from an analysis of gravity anomalies and a flexural model of the lithosphere. J Geophys Res 8(B10):8171–8191. doi: 10.1029/JB088iB10p08171 CrossRefGoogle Scholar
- Melosh HJ, Williams CA (1989) Mechanics of Graben formation in crustal rocks: a finite element analysis. J Geophys Res 94:13961–13973. doi: 10.1029/JB094iB10p13961 CrossRefGoogle Scholar
- Molnar P, Tapponier P (1975) Cenozoic tectonics of Asia: effects of continental collision. Science 189:419–426. doi: 10.1126/science.189.4201.419 CrossRefGoogle Scholar
- Pêcher A (1989) The metamorphism in the central Himalaya. J Metamorph Geol 7:31–41. doi: 10.1111/j.1525-1314.1989.tb00573.x CrossRefGoogle Scholar
- Pêcher AA (1991) The contact between the Higher Himalayan crystallines and the Tibetan sedimentary series: Miocene large-scale dextral shearing. Tectonics 10:587–598. doi: 10.1029/90TC02655 CrossRefGoogle Scholar
- Platt JP (1993) Exhumation of high pressure rocks: a review of concepts and processes. Terra Nova 5:119–133. doi: 10.1111/j.1365-3121.1993.tb00237.x CrossRefGoogle Scholar
- Schelling D (1992) The tectonostratigraphy and structure of the eastern Nepal Himalaya. Tectonics 11:925–943. doi: 10.1029/92TC00213 CrossRefGoogle Scholar
- Shanker D, Kapur N, Shing B (2002) Thrust-wedge mechanics and coeval development of normal and reverse faults in the Himalayas. J Geol Soc Lond 159:273–280. doi: 10.1144/0016-764901-059 CrossRefGoogle Scholar
- Sibson RH (1994) Crustal stress, faulting and fluid flow. Geofluids: origin, migration, and evolution of fluids in sedimentary basins. Special Publ Geol Soc Lond 54:15–28. doi: 10.1144/GSL.SP.1990.054.01.02 CrossRefGoogle Scholar
- Spencer JE (1984) Role of tectonic denudation in warping and uplift of low-angle normal fault. Geology 12:95–98. doi: 10.1130/0091-7613(1984)12<95:ROTDIW>2.0.CO;2 CrossRefGoogle Scholar
- Stephansson O, Barner H (1971) The finite element method in tectonic processes. J Phys Earth Planet interior 4:301–321CrossRefGoogle Scholar
- Timoshenko SP, Goodier JN (1970) Theory of elasticity. In: McGraw-Hill (ed) 3rd edn. London press, pp 567Google Scholar
- Upreti BN (1999) An overview of the stratigraphy and tectonics of the Nepal Himalaya. J Asian Earth Sci 17:577–606. doi: 10.1016/S1367-9120(99)00047-4 CrossRefGoogle Scholar
- Wang K, He J, Davis EE (1997) Transform push, oblique subduction resistance, and intraplate stress of the Juan de Fuca plate. J Geophys Res 102:661–674. doi: 10.1029/96JB03114 CrossRefGoogle Scholar
- Zienkiewicz OC, Cheung YK (1967) The finite element method in structural and continuum mechanics. McGraw-Hill Publishing Co. LTD., EnglandGoogle Scholar