Structural, geochronological and geochemical evidence for two distinct thrust sheets in the ‘Main Central thrust zone’, the Main Central thrust and Ramgarh–Munsiari thrust: implications for upper crustal shortening in central Nepal

2014 ◽  
Vol 412 (1) ◽  
pp. 221-245 ◽  
Author(s):  
S. Khanal ◽  
D. M. Robinson ◽  
S. Mandal ◽  
P. Simkhada
Keyword(s):  
Main Central Thrust ◽  
Crustal Shortening ◽  
Geochemical Evidence ◽  
Central Nepal ◽  
Thrust Zone ◽  
Thrust Sheets

Pressure-temperature-time path discontinuity in the Main Central thrust zone, central Nepal

Geology ◽  
2001 ◽  
Vol 29 (7) ◽  
pp. 571 ◽  
Author(s):  
Matthew J. Kohn ◽  
Elizabeth J. Catlos ◽  
Frederick J. Ryerson ◽  
T. Mark Harrison
Keyword(s):  
Main Central Thrust ◽  
Time Path ◽  
Central Nepal ◽  
Thrust Zone ◽  
Temperature Time

Assessing Quaternary reactivation of the Main Central thrust zone (central Nepal Himalaya): New thermochronologic data and numerical modeling

Geology ◽  
2009 ◽  
Vol 37 (8) ◽  
pp. 731-734 ◽  
Author(s):  
X. Robert ◽  
P. van der Beek ◽  
J. Braun ◽  
C. Perry ◽  
M. Dubille ◽  
...  
Keyword(s):  
Numerical Modeling ◽  
Main Central Thrust ◽  
Nepal Himalaya ◽  
Central Nepal ◽  
Thrust Zone

scholarly journals The Geology of the Rolwaling-Lapchi Kang Himalayas, East-Central Nepal: preliminary findings

1987 ◽  
Vol 4 ◽  
Author(s):  
Daniel Schelling
Keyword(s):  
Brittle Deformation ◽  
The South ◽  
Main Central Thrust ◽  
East Central ◽  
The North ◽  
Central Nepal ◽  
Main Boundary Thrust ◽  
Structural Discontinuity ◽  
Thrust Zone

Between the Tethyan sediments to the north and the Main Boundary Thrust to the south ten lithotectonic units have been identified in the Rolwaling-Lapchi Kang Himalayas and the Tamba Kosi region of east-central Nepal. These are (1) the Rolwaling Granites, (2) the Rolwaling Paragneisses, (3) the Rolwaling Migmatites, (4) the Alampu Schists, (5) the Khare Phyllites , (6) The Chagu-ChilangkaAugen Gneisses; (7) The Laduk Phyllites, (8) the Suri Dhoban Augen Gneisses, (9) the Rarnechap Group, and (10) the Mahabharat Crystallines. The Main Central Thrust (MCT) is a major lithologic, metamorphic and structural discontinuity separating the overthrust Higher Himalayan crystallines from the underthrust Lesser Himalayan metasediments. The Mahabharat Crystallines are an outlying klippe of Higher Himalayan rocks, underlain by the MCT, that has been thrust a minimum of 80 kilometers over the underlying Lesser Himalayan metasediments. Extending approximately 5 km below the MCT and 15 km above the MCT the Himalayas are a shear-thrust zone exhibiting ductile, brittle-ductile and brittle deformation as well as an inverted metamorphic sequence.

scholarly journals Characteristics and field relation of Ulleri Augen Gneiss to country rocks in the Lesser Himalaya: A case study from Syaprubesi-Chhyamthali area, central Nepal

2019 ◽  
Vol 58 ◽  
pp. 89-96
Author(s):  
Jharendra K.C. ◽  
Kabi Raj Paudyal
Keyword(s):  
Geological Mapping ◽  
Lesser Himalaya ◽  
Main Central Thrust ◽  
Nepal Himalaya ◽  
Field Relation ◽  
Central Nepal ◽  
Thrust Zone ◽  
Augen Gneiss ◽  
Host Rocks

The distribution of Ulleri Augen Gneiss and its origin in the Lesser Nepal Himalaya adjacent to the Main Central Thrust zone is stilla debate among the geo-scientists. Geological mapping was carried out along the Syaprubesi-Chhyamthali area of central Nepal with the aim to study the field relation, distribution, deformation and metamorphism of the Ulleri Augen Gneiss. During mapping, close traverses were set to observe the field relation and a number of systematic samples were collected for analysis of composition and texture. Some preliminary findings were obtained related to its geological position and distribution. This gneiss is hosted within the Kuncha Formation, the oldest unit of the Nawakot Group in the Lesser Himalaya. It has been evolved within this unit as a tabular form in some places and lenses in other places. It shows both concordant (i.e., sill type) and discordant (i.e., dike type) relationship with the host rock. It is characterized by augen-shaped porphyroblasts of K-feldspar and S-C mylonitic texture showing top to the SW sense of shear. The S-C structures and lineated textures shown by the minerals are associated with the shearing caused by the movement along the MCT during the syn-MCT metamorphic deformation. It is characterized in different types of lithologies such as augen gneiss, banded gneiss and two-mica gneiss. An attempt is made to explain the petrological characteristics and field relation of the Ulleri Augen Gneiss with the host rocks along with structural aspects. Based on the field relation and texture analysis, the evolution of the protolith of this Ulleri Augun Gneiss can be interpreted as a multi-story emplacement within the host rocks during and immediately after the sedimentation.

scholarly journals Geology and structure of the Pokhara-Piuthan area, central Nepal

1982 ◽  
Vol 2 ◽  
pp. 5-29
Author(s):  
Kazunori Arita ◽  
Daigoro Hayashi ◽  
Mitsuo Yoshida
Keyword(s):  
Metamorphic Grade ◽  
Geological Mapping ◽  
The Other ◽  
Main Central Thrust ◽  
Transitional Area ◽  
Central Nepal ◽  
Other Hand ◽  
Thrust Zone ◽  
Present Area

The geological mapping of the present area revealed that the area is a transitional area between central and western Nepal. The Kali Gandaki - Bari Gad fault which runs obliquely to the general Homalayan trend separates the present area lithostrato- tectonically into the northeast and soutewest units. Both units are in contrast each other in many respects. The northeast unit comprises the Tibetan Tethys, Himalayan gneiss, Main Central Thrust, Baglung and Bihadi zones. The last two are composed of the Midland meta- sediment Group of Riphean to Eocambrian age and autochthonous in character. The Himalayan gneisses are thrust over the Midland meta-sediments by the Main Central Thrust zone forming a klippe in the southwest unit. On the other hand the southwest unit consists mainly of slightly metamorphosed sediments probably of Paleozoic age which are folded and faulted as compared to those of the northeast unit. The metamorphic grade of the latter is obviously higher than the foemer. The present area, particularly the Kali Gandaki. Bari Gad fault is of exteme significance in considering the tectonic flame of the Nepal Himalayas.

Characterising the metamorphic discontinuity across the Main Central Thrust Zone of eastern-central Nepal

2015 ◽  
Vol 101 ◽  
pp. 83-100 ◽  
Author(s):  
Jiamin Wang ◽  
Jinjiang Zhang ◽  
Chunjing Wei ◽  
SantaMan Rai ◽  
Meng Wang ◽  
...  
Keyword(s):  
Main Central Thrust ◽  
Central Nepal ◽  
Thrust Zone

scholarly journals Geology and structure of the main central thrust zone of the annapurna range, central Nepal Himalayas

1982 ◽  
Vol 2 ◽  
pp. 31-50
Author(s):  
Takashi Kano
Keyword(s):  
Thrust Fault ◽  
Main Central Thrust ◽  
The Third ◽  
Tectonic History ◽  
Central Nepal ◽  
Thrust Zone ◽  
Mode Of Occurrence ◽  
Three Stages ◽  
Augen Gneiss

The present paper describes the geology, structure, tectonic history and petrographical feature of lithologic constituents of the region around (MCT) zone. The report area is lithologically divided into four geologic units; the Midland zone, the MCT zone, the himalayan gneiss zone and the Tibetan Tethys zone. The MCT zone is distinguished by the lower augen gneiss zone, (MCT-2) and the upper thrust fault (MCT-1). Three stages of deformations are recognized in the area: the first, the two sets of widespread foldings with striation-like forms, which are comparable to the southwards thrusting of MCT; and the third, latest upwards movement of the Higher Himalayas. Mode of occurrence and petrographical feature of augen gneisses suggest close genetical relations with the movements of MCT and/or the activity of younger turmaline granites.

scholarly journals Kinematic and tectonic significance of microstructures and crystallographic fabrics within quartz mylonites from the Assynt and Eriboll regions of the Moine thrust zone, NW Scotland

1986 ◽  
Vol 77 (2) ◽  
pp. 99-125 ◽  
Author(s):  
R. D. Law ◽  
M. Casey ◽  
R. J. Knipe
Keyword(s):  
Strain Path ◽  
Extensional Flow ◽  
Crystallographic Preferred Orientation ◽  
X Ray ◽  
Tectonic Significance ◽  
Thrust Zone ◽  
Thrust Sheets ◽  
Strain Paths ◽  
Tectonic Loading ◽  
Microstructural Studies

ABSTRACTUsing a combination of optical microscopy and X-ray texture goniometry, an integrated microstructural and crystallographic fabric study has been made of quartz mylonites from thrust sheets located beneath, but immediately adjacent to, the Moine thrust in the Assynt and Eriboll regions of NW Scotland. A correlation is established between shape fabric symmetry and pattern of crystallographic preferred orientation, a particularly clear relationship being observed between shape fabric variation and quartza-axis fabrics.Coaxial strain paths dominate the internal parts of the thrust sheets and are indicated by quartzc- anda-axis fabrics which are symmetrical with respect to foliation and lineation. Non-coaxial strain paths are indicated within the more intensely deformed quartzites located near the boundaries of the sheets by asymmetricalc- anda-axis fabrics. These kinematic interpretations are supported by microstructural studies. At the Stack of Glencoul in the northern part of the Assynt region, the transition zone between these kinematic (strain path) domains is located at approximately 20 cm beneath the Moine thrust and is marked by a progression from symmetrical cross-girdlec-axis fabrics (30cm beneath the thrust), through asymmetrical cross-girdlec-axis fabrics to asymmetrical single girdlec-axis fabrics (0·5 cm beneath the thrust).Tectonic models (incorporating processes such as extensional flow, gravity spreading and tectonic loading) which may account for the presence of strain path domains within the thrust sheets are considered, and their compatibility with local thrust sheet geometries assessed.

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