Journal of Geological Society of India (Online archive from Vol 1 to Vol 78)

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The Lesser Himalayan Duplex in Sikkim: Implications for Variations in Himalayan Shortening


Affiliations
1 Department of Earth and Environmental Sciences, University of Rochester, Rochester, NY 14627, United States
2 CSIR Centre for Mathematical Modelling and Computer Simulation, Bangalore - 560 037, India
     

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Thrust duplexes account for large fractions of the total shortening in most fold-thrust belts (FTBs). They also provide an efficient mechanism for transferring slip upward from the basal decollement and for transporting roof thrust sheets over long distances. The Lesser Himalayan duplex (LHD) plays a prominent role in the overall evolution of the Himalayan FTB and has been described from Garhwal-Kumaon to Bhutan. In Sikkim the LHD shows unique structural geometry and has been responsible for transporting crystalline thrust sheets (MCT 1 and MCT 2) farther southward than other parts of the Himalaya. Such lateral variations in LHD geometry imply variations in the kinematic history of the Lesser Himalaya and variations in shortening and shortening history along the length of the Himalayan arc, and these are reflected in observable large scale structural patterns.

Keywords

Duplex Kinematics, Balanced Cross-Section, Fold-Thrust Belt, Lesser Himalaya, Darjeeling-Sikkim.
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  • The Lesser Himalayan Duplex in Sikkim: Implications for Variations in Himalayan Shortening

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Authors

Gautam Mitra
Department of Earth and Environmental Sciences, University of Rochester, Rochester, NY 14627, United States
Kathakali Bhattacharyya
Department of Earth and Environmental Sciences, University of Rochester, Rochester, NY 14627, United States
Malay Mukul
CSIR Centre for Mathematical Modelling and Computer Simulation, Bangalore - 560 037, India

Abstract


Thrust duplexes account for large fractions of the total shortening in most fold-thrust belts (FTBs). They also provide an efficient mechanism for transferring slip upward from the basal decollement and for transporting roof thrust sheets over long distances. The Lesser Himalayan duplex (LHD) plays a prominent role in the overall evolution of the Himalayan FTB and has been described from Garhwal-Kumaon to Bhutan. In Sikkim the LHD shows unique structural geometry and has been responsible for transporting crystalline thrust sheets (MCT 1 and MCT 2) farther southward than other parts of the Himalaya. Such lateral variations in LHD geometry imply variations in the kinematic history of the Lesser Himalaya and variations in shortening and shortening history along the length of the Himalayan arc, and these are reflected in observable large scale structural patterns.

Keywords


Duplex Kinematics, Balanced Cross-Section, Fold-Thrust Belt, Lesser Himalaya, Darjeeling-Sikkim.

References