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Configuration of Rodinia supercontinent (~ 1100-800 Ma) containing all the continent except North China. a The position of India and microcontinent in the northern end Indian plate, after Zhao et al. (2018). b Global distribution of Grenville orogeny map based on paleo-geography during the Neoproterozoic era (after Rino et al. 2008)
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Granitoids of various ages ranging from Proterozoic to Tertiary occur throughout the Himalayan fold-thrust belt. The occurrence of the Neoproterozoic
granitoids is very less in the Himalayan orogen. One of the best example of Neoproterozoic granitoids is Chor granitoid, which is the
intrusive granite body in the Paleoproterozoic of the Lesser Himal...
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The Dharan–Mulghat area of the eastern Nepal can be divided into three tectonic units: the Higher Himalayan Crystallines, the Lesser Himalayan Sequence and the Siwaliks from north to south separated by the Main Central Thrust (MCT) and Main Boundary Thrust (MBT), respectively. The Lesser Himalayan Sequence is divided into two groups separated by Ch...
The Himalaya has undergone various tectonic activities which resulted in variant geology in the region. In the Himalayan region, due to the high degree of schistocity, fracturing and shearing, weak rocks such as mudstone, shale, slate, phyllite, schist, highly schistose gneiss and the rock mass of the tec-tonic fault zones are not capable to withst...
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Citations
... Zircon standard 91500 is being used as a primary standard for instrumental drift, isotopic fractionation and mass bias correction and Plešovice is being used as a secondary standard for quality control. The laboratory has been utilised for research projects on understanding complex geological problems of the Himalaya and in studies addressing 1) sediment routing of Paleo-Floods (U-Pb Zircon Geochronology: as a provenance indicator) along the major rivers in Ladakh and Zanskar region, 2) Weathering Congruency and provenance of Teesta River basin, Indus River and other important river system in The (Singh et al., 2017). In Uttarakhand Himalaya, Mukherjee et al. (2017 and Jain et al. (in press) suggested a comprehensive model describing different terrains and litho tectonic units across Uttarakhand Himalaya based chiefly on zircon ages along with Sr and Nd isotopic constraints. ...
The Main Boundary Thrust (MBT) is studied along the Baliya-Amritpur-Jamrani road section of the Baliya Nala-Gola River valley including an isolated granite body, associated with MBT hanging wall in the Kumaun region of the NW-Himalaya. In this study, we have reviewed available Fission-Track Thermochronological ages and seismicity data in combination with the new field evidence and geomorphological data to understand the mechanism for the exhumation of the Amritpur Granite Body (AGB) and the tectonic movement history along the MBT. Furthermore, the timing of the tectonic activity along the MBT and its role in the exhumation of the AGB are explored. The study focused on two different locations, where the Amritpur Granite is in direct contact with the Siwalik rocks along the MBT. The available apatite and zircon Fission-Track (AFT/ZFT) ages are range between 11.3 Ma to 14.7 Ma with a mean of 13.4 Ma and 12.4 Ma to 15.4 Ma with a mean of 13.9 Ma respectively. Mean AFT and ZFT ages of the AGB have similar age trends from the MBT to the Salari
Thrust, which indicates that the AGB was rapidly uplifted and exhumed along the MBT from the basement at a depth of ca. 8-10 km during the middle Miocene (ca. 14-13 Ma). Similarly, the AFT ages of the sandstone samples from the contact zone
of AGB and middle Siwalik (MBT's footwall side) are completely reset and age ranges between 4.4 Ma to 5.5 Ma with a mean of ~5.0 Ma reveal the tectonic reactivation of the MBT during Pliocene-Quaternary period. The morphometric trends suggest that the AGB has a lower erosion susceptibility than the rocks available on the northern side of AGB. Furthermore, an aggregated map and morphometric index revealed that the AGB has aligned along the regional faults (i.e., MBT and Salari Thrust), which also indicate the demarcation of the dendritic drainage pattern of the watershed with low susceptibility to erosion. The scattered pattern of seismicity also indicates the tectonic activity along the MBT almost ceased after the Pliocene-Quaternary period. Based on the morphometry, field evidences and available FT thermochronological age data, we envisage that the AGB was exhumed to the surface from the basement as 'Tectonic Slivers' during the development and reactivation of the MBT between Miocene to Pliocene period.
Fission-track (FT) thermochronological analysis of detrital apatite and zircon derived
from the lower and middle Siwalik Group of the sub-Himalaya allows the reconstruction of the long-term exhumation history of the Higher Himalayan Crystalline (HHC) and Lesser Himalayan Sequence (LHS), and also the provenance of the Siwalik sediments. Here, we report 14 detrital apatite and zircon fission-track (AFT/ZFT) ages of lower and middle Siwalik subgroups of the Kumaun region, northwest Himalaya. Detrital FT ages suggest that all sandstone samples were never buried below the temperature range of 90� to 100�C and remained as unreset to retain a signal of source-area exhumation. A detrital AFT age from sandstone sample at close proximity to the Main Boundary Thrust (MBT) is 4.4 ± 0.5 Ma (Pliocene time) which is completely reset and younger than the depositional age, while the detrital ZFT ages of the same sample are unrest. The AFT age represents the time of reactivation of the MBT during which ZFT ages were not affected. This study revealed that the provenances of Siwalik sediments are located majorly in the MBT hinterland areas and the nearest sources are Amritpur granite, the outer Lesser Himalayan metasedimentary (LHMS) zone, Almora klippe, Ramgarh thrust sheet, and the overlying Tethyan Himalayan Sequence. These source areas can be attributed to the development of local drainage networks in the Ramganga-Kosi drainage basin during late Miocene to Pliocene (i.e., �9 to 4 Ma). Based on detrital FT datasets, it has been envisaged that different tectonic activities in the MBT hinterland area between Miocene and Pliocene Periods cause the tectonic upliftment and exhumation of source areas and supply the sediment to the Siwalik foreland basin.
In this Chapter, the Mandi-Kataula-Bajaura section of Himachal Himalaya offers an invaluable opportunity to observe the lithology and structures of Pandoh Syncline. It comprises (i) the Lesser Himalayan Sequence, which includes Shali and Rampur Groups, (ii) low to medium grade metamorphic of the Lesser Himalayan Crystallines, which includes the Kulu thrust sheet of the Himachal Himalaya. The road dip-section is almost perpendicular to the major strike parallel and cross-cuts the litho-tectonic units.
In the NW-Himalaya, the Indian state Himachal Pradesh consists of almost 1 all the lithotectonic units of the Himalayan fold-thrust belts. This field excursion 2 guide is designed to showcase the structural geological marvels of the Mandi-3
In the Himachal region of the NW-Himalaya almost all the lithotectonic units of the Himalayan fold-thrust belts. This field excursion guide is designed to showcase the structural geological marvels of the Mandi-Kullu-Manali section along the Beas River valley from the Main Boundary Thrust (MBT) to the South Tibetan Detachment System (STDS). This dip-section along the road provides an excellent opportunity to study the structural imprints of MBT, Panjal/Chail Thrust (also known as Main Central Thrust), Vaikrita Thrust and the position of STDS. In this field guide chapter, we mainly present the deformation structures metamorphism and economic mineral occurrences in the study area. This field excursion guide encounters the following litho units: (i) metasedimentary rocks of Lesser Himalayan Sequence (LHS), (ii) low- to medium-grade crystalline rocks of Lesser Himalayan Crystalline thrust sheets including Chail and Jutogh groups and intrusive Paleozoic granites, (iii) High-grade crystallines and migmatites of the Higher Himalayan Crystalline (HHC) including intrusive Paleozoic leucogranites, (iv) Tethyan Himalayan Sequence (THS). Based on our field, structural and metamorphic observation, we try to distinguish the Chail formation, Jutogh and Vaikrita Groups, which have been considered as a single unit ‘Haimanta group’ (Webb et al. 2011 and reference therein).
Many elongated, lenticular intrusive granitoids of various ages are scattered within the Lesser Himalayan metamorphic belt, all along the ~ 2500 km length of the Himalaya. The Neoproterozoic Chaur granitoid complex (CGC) of Chaur area is characterized by foliated and non-foliated peraluminous granites occurring as an isolated granitoid body within the Jutogh group. In this work, we present the whole-rock geochemical data of six samples and U-Pb (zircon) geochronology of two different granites of the CGC and one granitic gneiss sample of Jutogh group from Himachal Pradesh of NW Himalaya. Our newly obtained results of U-Pb (zircon) geochronological age populations from all granitoid sample yield age between 766 and 1080 Ma with few younger phases and older inherited ages. We obtained U-Pb (zircon) ages from two sample of the CGC, out of which one gives the two prominent age spectra for 206 Pb/ 238 U with weighted mean age of 826 ± 4.97/9.74 Ma, MSWD = 0.65, n = 8) and 868 ± 6.21/12.17 Ma, MSWD = 1.28, n = 7). Similarly, another granite of CGC gives the weight mean age of 929 ± 6.48/12.70 Ma (MSWD = 1.28, n = 11). The granitic gneiss of the Jutogh group also gives two prominent age spectra for 206 Pb/ 238 U, with weighted mean age of 861 ± 8.27/16.21 Ma (MSWD = 0.31, n = 10) and 932 ± 10.0/19.6 Ma (MSWD = 1.57, n = 8). The whole-rock geochemical data show calc-alkaline composition of all six samples and suggest a subduction-related accretion setup. The depletion in the Nb, Sr, P and Ti in CGC indicates a magmatic arc type magma. U-Pb (zircon) ages of all three samples have a similar phase of crystallization and we defined as ~ 930 Ma age of crystallization of CGC. The whole-rock geochemical data suggest that all the three samples possibly came from the same magma source during the Neoproterozoic magmatic events in the northern marginal part of the Indian plate. It is envisaged that the unknown microcontinents present in the northern margin collide with the Indian plate and the subduction process coincides with the onset of the Grenvillian orogeny during the Neoproterozoic. The extension of these minor collision orogen may have been connected with Lhasa, Trim as well as Greater India blocks. In this collisional process, the crustal melt was generated and intruded in the form of CGC within the pre-existing Paleoproterozoic crust of Indian plate. The whole process indicates that the subduction of unknown microcontinent under the Indian plate may be correlated with the Grenvillian orogeny and formation of the Rodinia supercontinent during Neoproterozoic.
