Kinematic analyses of orogen-parallel L-tectonites from Pelling-Munsiari thrust of Sikkim Himalayan fold thrust belt: Insights from multiple, incremental strain markers

Das, Jyoti Prasad; Bhattacharyya, Kathakali; Mookerjee, Matty; Ghosh, Pritam

doi:10.1016/j.jsg.2016.07.005

Cited by 15 publications

(3 citation statements)

References 39 publications

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“…3C), schist/phyllite, and augen gneiss. The contacts between the Paleoproterozoic granitoids and metasedimentary rocks along the Himalaya vary from intrusive to sheared (Bhattacharyya et al, 2015b;Das et al, 2016;Mandal et al, 2016). In our study area, one of these contacts at the southern margin of the Askot klippe is sheared and juxtaposes 1857 ± 19 Ma granite-granodiorite gneiss atop a sequence of metasedimentary and metavolcanic rocks (Mandal et al, 2016).…”

Section: Ramgarh-munsiari Thrust Sheetmentioning

confidence: 75%

Examining the tectono-stratigraphic architecture, structural geometry, and kinematic evolution of the Himalayan fold-thrust belt, Kumaun, northwest India

et al. 2019

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Existing structural models of the Himalayan fold-thrust belt in Kumaun, northwest India, are based on a tectono-stratigraphy that assigns different stratigraphy to the Ramgarh, Berinag, Askot, and Munsiari thrusts and treats the thrusts as separate structures. We reassess the tectono-stratigraphy of Kumaun, based on new and existing U-Pb zircon ages and whole-rock Nd isotopic values, and present a new structural model and deformation history through kinematic analysis using a balanced cross section. This study reveals that the rocks that currently crop out as the Ramgarh, Berinag, Askot, and Munsiari thrust sheets were part of the same, once laterally continuous stratigraphic unit, consisting of Lesser Himalayan Paleoproterozoic granitoids (ca. 1850 Ma) and metasedimentary rocks. These Paleoproterozoic rocks were shortened and duplexed into the Ramgarh-Munsiari thrust sheet and other Paleoproterozoic thrust sheets during Himalayan orogenesis. Our structural model contains a hinterland-dipping duplex that accommodates ∼541–575 km or 79%–80% of minimum shortening between the Main Frontal thrust and South Tibetan Detachment system. By adding in minimum shortening from the Tethyan Himalaya, we estimate a total minimum shortening of ∼674–751 km in the Himalayan fold-thrust belt. The Ramgarh-Munsiari thrust sheet and the Lesser Himalayan duplex are breached by erosion, separating the Paleoproterozoic Lesser Himalayan rocks of the Ramgarh-Munsiari thrust into the isolated, synclinal Almora, Askot, and Chiplakot klippen, where folding of the Ramgarh-Munsiari thrust sheet by the Lesser Himalayan duplex controls preservation of these klippen. The Ramgarh-Munsiari thrust carries the Paleoproterozoic Lesser Himalayan rocks ∼120 km southward from the footwall of the Main Central thrust and exposed them in the hanging wall of the Main Boundary thrust. Our kinematic model demonstrates that propagation of the thrust belt occurred from north to south with minor out-of-sequence thrusting and is consistent with a critical taper model for growth of the Himalayan thrust belt, following emplacement of midcrustal Greater Himalayan rocks. Our revised stratigraphy-based balanced cross section contains ∼120–200 km greater shortening than previously estimated through the Greater, Lesser, and Subhimalayan rocks.

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Section: Ramgarh-munsiari Thrust Sheetmentioning

confidence: 75%

Examining the tectono-stratigraphic architecture, structural geometry, and kinematic evolution of the Himalayan fold-thrust belt, Kumaun, northwest India

et al. 2019

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“…We explain this discrepancy due to the interchangeable nature of the X ‐ and Y ‐axes in the oblate ellipsoid shape ( X ≥ Y > Z; Figure 8). The PT also forms L‐tectonite klippen within the Tista half‐window (LTK in Figure 1b), where the strain ellipsoids have a prolate shape ( X >> Y ≥ Z ) (Bhattacharyya, Dwivedi, et al., 2015; Das et al., 2016, 2021). This interchangeable nature in the strain axes is not observed in these rocks, and the X ‐axes are subparallel to the mineral stretching lineations (Bhattacharyya, Dwivedi, et al., 2015; Das et al., 2021).…”

Section: Discussionmentioning

confidence: 99%

Penetrative Strain and Partitioning of Convergence‐Related Shallow Crustal Shortening, Across Scales, in the Lesser‐ and Sub‐Himalayan Thrusts: Insights From the Eastern Himalaya, Sikkim

2022

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“…10; Bhattacharyya et al, 2015a). By estimating the incremental kinematic vorticity number (Wk) from quartz c-axes fabric, oblique fabric, and sub-grains, a first-order, kinematic path of these Ltectonites are reconstructed (Das et al, 2016). Quartz c-axes fabric suggests that the deformation initiated as pure-shear dominated (~56-96%) that progressively became simple-shear dominated (~29-54%), as recorded by oblique fabric and sub-grains in the Ltectonites.…”

Section: Sikkimmentioning

confidence: 99%

Tectonics of the Western, Sikkim and Arunachal Himalaya

Jain¹,

Thakur²,

Joshi³

et al. 2020

PINSA

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During the period 2016-2020, the Indian scientists undertook extensive research in the Himalayan Orogen, which incorporated extensive field mapping, structural analysis, geochemistry, metamorphic and igneous petrology, stratigraphy and palaeontology, Ar/Ar and U-Pb geochronology, besides low-temperature thermochronology. These activities were almost spread throughout the belt from western sector through Garhwal-Kumaon, Sikkim, Bhutan and Arunachal Pradesh. In addition, research was also undertaken using magnetotelluric methods for large-scale tectonics, seismology, paleoseismology and other disciplines, which are covered in other contributions. National laboratories have now started generating highresolution U-Pb dates, which have been providing impetus to model Himalayan tectonics, besides modelling its Paleoproterozoic and Neoproterozoic configuration.

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Kinematic analyses of orogen-parallel L-tectonites from Pelling-Munsiari thrust of Sikkim Himalayan fold thrust belt: Insights from multiple, incremental strain markers

Cited by 15 publications

References 39 publications

Examining the tectono-stratigraphic architecture, structural geometry, and kinematic evolution of the Himalayan fold-thrust belt, Kumaun, northwest India

Examining the tectono-stratigraphic architecture, structural geometry, and kinematic evolution of the Himalayan fold-thrust belt, Kumaun, northwest India

Penetrative Strain and Partitioning of Convergence‐Related Shallow Crustal Shortening, Across Scales, in the Lesser‐ and Sub‐Himalayan Thrusts: Insights From the Eastern Himalaya, Sikkim

Tectonics of the Western, Sikkim and Arunachal Himalaya

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