The Central Indian Tectonic Zone (CITZ) is a Proterozoic suture along which the Northern and Southern Indian Blocks are inferred to have amalgamated forming the Greater Indian Landmass. In this study, we use the metamorphic and geochronological evolution of the Gangpur Schist Belt (GSB) and neighbouring crustal units to constrain crustal accretion processes associated with the amalgamation of the Northern and Southern Indian Blocks. The GSB sandwiched between the Bonai Granite pluton of the Singhbhum craton and granite gneisses of the Chhotanagpur Gneiss Complex (CGC) links the CITZ and the North Singhbhum Mobile Belt. New zircon age data constrain the emplacement of the Bonai Granite at 3,370 ± 10 Ma, while the magmatic protoliths of the Chhotanagpur gneisses were emplaced at c. 1.65 Ga. The sediments in the southern part of the Gangpur basin were derived from the Singhbhum craton, whereas those in the northern part were derived dominantly from the CGC. Sedimentation is estimated to have taken place between c. 1.65 and c. 1.45 Ga. The Upper Bonai/Darjing Group rocks of the basin underwent major metamorphic episodes at c. 1.56 and c. 1.45 Ga, while the Gangpur Group of rocks were metamorphosed at c. 1.45 and c. 0.97 Ga. Based on thermobarometric studies and zircon–monazite geochronology, we infer that the geological history of the GSB is similar to that of the North Singhbhum Mobile Belt with the Upper Bonai/Darjing and the Gangpur Groups being the westward extensions of the southern and northern domains of the North Singhbhum Mobile Belt respectively. We propose a three‐stage model of crustal accretion across the Singhbhum craton—GSB/North Singhbhum Mobile Belt—CGC contact. The magmatic protoliths of the Chhotanagpur Gneisses were emplaced at c. 1.65 Ga in an arc setting. The earliest accretion event at c. 1.56 Ga involved northward subduction and amalgamation of the Upper Bonai Group with the Singhbhum craton followed by accretion of the Gangpur Group with the Singhbhum craton–Upper Bonai Group composite at c. 1.45 Ga. Finally, continent–continent collision at c. 0.96 Ga led to the accretion of the CGC with the Singhbhum craton–Upper Bonai Group–Gangpur Group crustal units, synchronous with emplacement of pegmatitic granites. The geological events recorded in the GSB and other units of the CITZ only partially overlap with those in the Trans North China Orogen and the Capricorn Orogen of Western Australia, indicating that these suture zones are not correlatable.
Dwelling, activated through gaze fixation for a prolonged time, is an essential task to be performed to select keys from on-screen keyboard present in the eye typing interface. Normally fixation on a key takes sufficient time which slows down eye typing rate. To get rid of it, researchers focused on minimizing or diminishing dwell time toward building a dwell-free interface. In this paper, we present an efficient dwellfree eye typing mechanism and compare it with a previous work with respect to text entry rate, learning rate and usability. The user experiment results reveal that newly proposed method performed slightly better than the other.
Mobile phone is mostly common communicating device in recent time but blind people have limited accessibility to that device. Due to the lack of their visual perception, blind people have different preferences towards interacting with a device. This work aims to find an effective interaction mode to access mobile phone by the visually impaired people in India. In Indian subcontinent people popularly use keypad-based handsets and are well habituated with the key based interaction. But the presence of a huge number of keys in keypad plays negative impact in interaction procedure for our target users. We explored how the detection time for a particular key in a jumble of keys varies with different keypad conditions where target users searched for a key only through the tactile sense. We report the preferable keypad type for our blind mobile users where detection for a particular key is made faster and less error prone. We found that the detection time for a particular key was significantly less and the detection was much accurate in a keypad containing only the functional keys rather than QWERTY or traditional 4×3 keypad.
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