Main Central Thrust

Many geologists have researched the Main Central Thrust using various different criteria such as lithology,[2][3] metamorphic isograd,[4] geochronology,[5] geochemistry,[6] and strain magnitude.

[2] These units (figure 1), from south to north, are: Knowledge of the kinematics of the Himalayan fault system is not as ideal as it has long been debated.

[15] The dominant problems are: Despite the difficulties in defining the Main Central Thrust, the following definitions of the Main Central Thrust have been made based on various criteria: By lithologic criteria, the Main Central Thrust is defined as the boundary between quartzite and phyllite, from the Lesser Himalayan Sequence; and the orthogneiss biotite-rich schist, which belongs to the Greater Himalayan Crystalline complex.

[6] By strain, the Main Central Thrust is defined as a broad zone which a few kilometers thick.

This zone accommodates most of the ductile shear zones and brittle thrust faults between the lowermost part of the Greater Himalayan Crystalline complex and the uppermost part of the Lesser Himalayan Sequence.

[7][8] None of the above definitions are precise because the Main Central Thrust developed and changes its style not only vertically but also along its strike, and even through time.

Figure 1. Simplified geological map of Himalaya. [ 9 ] The Main Central Thrust is indicated by solid line and triangles.
Figure 2. Kinematics models of Himalayan orogen (modified from Webb et al., 2011) showing three models of how the Greater Himalayan Crystalline complex was placed over the Lesser Himalayan Sequence. LHS: the Lesser Himalayan Sequence; GHC: the Greater Himalayan Crystalline complex; THS: the Tethyan Himalayan Sequence; MCT: the Main Central Thrust; STD: the South Tibetan Detachment; ITS: Indus-Tsangpo suture zone.