Asymmetric development of the Himalaya: quantitative evidence from strain analysis in Kimin-Ziro-Tamen area, Arunachal Lesser Himalaya, India

2021 ◽  
Author(s):  
Gaurav Joshi ◽  
Amar Agarwal ◽  
K. K. Agarwal ◽  
P. V. Singh ◽  
Sushmita Singh
Keyword(s):  
Strain Analysis ◽  
Lesser Himalaya ◽  
Quantitative Evidence ◽  
The Himalaya

Tectonics and evolution of the central sector of the Himalaya

1988 ◽  
Vol 326 (1589) ◽  
pp. 151-175 ◽  
Keyword(s):  
Late Holocene ◽  
Granulite Facies ◽  
Lesser Himalaya ◽  
Main Central Thrust ◽  
Indian Shield ◽  
Ganga Basin ◽  
Granulite Facies Metamorphism ◽  
Slowing Down ◽  
Main Boundary Thrust ◽  
The Himalaya

Following the India-Asia collision, intracrustal movements along the Main Central Thrust (MCT) and Main Boundary Thrust (MBT) in a piggy-back-style, thrust duplexes developed that uplifted the Vaikrita (Central) crystallines of the basement to more than 8000 m elevation. Blocking of subduction on the suture and slowing down of movement on the MCT led to the formation of the Trans-Himadri (Malari) Thrust between the Vaikrita basement and the Tethyan cover sediments, and to gravity-induced backfolds and backthrusts in the latter. The Vaikrita crystallines underwent upper amphibolite to lower granulite facies metamorphism at 600-650 °C and more than 5 kbar (1 kbar = 101 *8 Pa) and migmatistation associated with 28-20 Ma old S-type granites that formed at 15-30 km depth during the culmination of metamorphism and thrust deformation. Delimited by the MCT and MBT, the Lesser Himalaya is made of Proterozoic sediments beneath the Almora nappe constituted of low- to medium-grade metamorphics and 1900+ 100 Ma old granitic gneisses and 560 + 20 Ma old granites. The Lesser Himilaya underwent considerable neotectonic rejuvenation during differential movements along the MBT. The frontal Siwalik molasse below the MBT was severely thrusted and folded in the late Holocene, and continued underthrusting of the Indian Shield beneath the Himalaya is manifest in the development and activation of the deep Himalayan Front Fault (HFF), which separates the Siwalik from the subRecent-Recent alluvial plain of the Ganga Basin.

Cambrian biostratigraphy of the Tal Group, Lesser Himalaya, India, and early Tsanglangpuan (late early Cambrian) trilobites from the Nigali Dhar syncline

2005 ◽  
Vol 142 (1) ◽  
pp. 57-80 ◽  
Author(s):  
NIGEL C. HUGHES ◽  
SHANCHI PENG ◽  
O. N. BHARGAVA ◽  
A. D. AHLUWALIA ◽  
SANDEEP WALIA ◽  
...  
Keyword(s):  
Southwest China ◽  
Early Cambrian ◽  
Lesser Himalaya ◽  
Geographic Proximity ◽  
Late Cambrian ◽  
Assemblage Zone ◽  
Late Neoproterozoic ◽  
Spiti Region ◽  
The Himalaya ◽  
Tethyan Himalaya

Precise biostratigraphic constraints on the age of the Tal Group are restricted to (1) a basal level correlative with the Anabarites trisulcatus–Protohertzina anabarica Assemblage Zone of southwest China, (2) a level near the boundary of the lower and upper parts of the Tal Group correlative with the early Tsanglangpuan Stage (Drepanuroides Zone), and (3) an interval low in the upper part of the Tal Group correlative with later in the Tsanglangpuan Stage (Palaeolenus Zone). These correlations are based on small shelly fossil and trilobite taxa. Other chronostratigraphic constraints include the marked negative δ13C isotopic excursion coincident with the transition from the Krol Group to the Tal Group. This excursion is used as a proxy for the Precambrian–Cambrian boundary in several sections worldwide and, if applied to the Lesser Himalaya, indicates that the boundary is at or just above the base of the Tal Group. The upper parts of the Tal Group may be of middle or late Cambrian age and might form proximal equivalents of sections in the Zanskar–Spiti region of the Tethyan Himalaya. Both faunal content and lithological succession are comparable to southwest China, furthering recent arguments for close geographic proximity between the Himalaya and the Yangtze block during late Neoproterozoic and early Cambrian time. Trilobites from the uppermost parts of the Sankholi Formation from the Nigali Dhar syncline are described and referred to three taxa, one of which, Drepanopyge gopeni, is a new species. They are the oldest trilobites yet described from the Himalaya.

scholarly journals Implications of the ongoing rock uplift in NW Himalayan interiors

2021 ◽  
Vol 9 (3) ◽  
pp. 463-485
Author(s):  
Saptarshi Dey ◽  
Rasmus C. Thiede ◽  
Arindam Biswas ◽  
Naveen Chauhan ◽  
Pritha Chakravarti ◽  
...  
Keyword(s):  
Hanging Wall ◽  
Active Surface ◽  
Kashmir Himalaya ◽  
Lesser Himalaya ◽  
The Core ◽  
Exhumation Rates ◽  
Differential Uplift ◽  
The Himalaya ◽  
Chenab River

Abstract. The Lesser Himalaya exposed in the Kishtwar Window (KW) of the Kashmir Himalaya exhibits rapid rock uplift and exhumation (∼3 mm yr−1) at least since the late Miocene. However, it has remained unclear if it is still actively deforming. Here, we combine new field, morphometric and structural analyses with dating of geomorphic markers to discuss the spatial pattern of deformation across the window. We found two steep stream segments, one at the core and the other along the western margin of the KW, which strongly suggest ongoing differential uplift and may possibly be linked to either crustal ramps on the Main Himalayan Thrust (MHT) or active surface-breaking faults. High bedrock incision rates (>3 mm yr−1) on Holocene–Pleistocene timescales are deduced from dated strath terraces along the deeply incised Chenab River valley. In contrast, farther downstream on the hanging wall of the MCT, fluvial bedrock incision rates are lower (<0.8 mm yr−1) and are in the range of long-term exhumation rates. Bedrock incision rates largely correlate with previously published thermochronologic data. In summary, our study highlights a structural and tectonic control on landscape evolution over millennial timescales in the Himalaya.

scholarly journals Study of regional geological structures in Ridi-Shantipur area of Gulmi district, Lesser Himalaya, west-central Nepal

2019 ◽  
Vol 58 ◽  
pp. 111-118
Author(s):  
Shrawan Shakya ◽  
Kabi Raj Paudyal
Keyword(s):  
Regional Scale ◽  
Lesser Himalaya ◽  
The North ◽  
Central Nepal ◽  
West Central ◽  
Continuous Shear ◽  
Deformation Event ◽  
Middle Member ◽  
Geological Units ◽  
The Himalaya

The study was carried out in the Lesser Himalaya between Ridi-Shantipur area of the Gulmi District, west-central Nepal. Two geological units: the Nourpul Formation and the Dhading Dolomite were mapped in the area. These units belong to the Nawakot Group as explained by several researchers in central Nepal. The Nourpul Formation can further be divided into three members based on distinct mappable lithology, which are named as the Lower Member, the Middle Member and the Upper Member, respectively. The area is highly folded with several local and regional anticlines and synclines; Ridi Khola Anticline, Ridi-Karikot Syncline, Ruru Anticline, Baletaksar-Gwadi Syncline, Huga-Bamgha Anticline, Rimuwa-Rudrabeni Syncline, Juhan-Eksing Anticline, Juniya-Limgha Syncline, Bharse-Thaple Anticline, and Chiureko Syncline, respectively from the south to the north. All the folds are trending along to the ESE-WNW direction. The origin of these folds can be linked with the thrust propagation in the Himalaya that can be explained with the deformation event D4. The Harewa Khola Thrust is the only one regional scale thrust mapped in the area. The thrust carries the older Nourpul Formation over the Dhading Dolomite with the indications of thrust related features like slickensides and fault-breccias. The thrust seems to propagate to the north. There is a continuous shear zone mapped in the outcrops from the Tal Khola-Aslewa-Eksingh-Gudrung-Juhang- Rupakot region as an indicator of the presence of the Badi Gad Fault in the region.

scholarly journals Geometric and strain analyses in folds of the area around Gankot, district Pithoragarh, Uttarakhand, India

2019 ◽  
Vol 4 (2-2) ◽  
pp. 19
Author(s):  
Swati Lata ◽  
Ravindra Kumar ◽  
Vaibhava Srivastava
Keyword(s):  
Shear Strain ◽  
Geometric Analysis ◽  
Strain Analysis ◽  
Strain Ratio ◽  
Two Dimensional ◽  
Lesser Himalaya ◽  
Dominant Classes ◽  
Shear Strains ◽  
High Degree ◽  
Very High

The study area around Gankot in Pithoragarh district of Uttarakhand belongs to the Thalkedar Limestone unit of Mandhali Formation, Tejam Group in Inner Sedimentary Zone of Lesser Himalaya, which exposes complexly folded and refolded structures. Geometric analysis carried out on the profile section of the fold tracing using dip isogon and orthogonal thickness parameters revealed presence of all the fold geometry suggested by Ramsay (1967) however the class 3 followed by class 1B are the most dominant classes in the study area when individual layers of the fold were studied. The study of folds as multilayered unit reveals that folds in study area belong to strongly non-analogous fold class of anisodeviatoric folds. In fold, the strain analysis has been done by drawing strain ellipse obtained by Inverse Thickness Method which is useful in estimating flattening strain even when the flattening is imposed obliquely to the fold’s axial trace. The finite two-dimensional flattening strain ratio (Rs) value ranged between 1 and 3.14 with an average Rs value of 1.60. The method of Srivastava and Gairola (2003) has also been used to obtain shear strain and flattening strain for the multilayered folds of study area. The results reveal that the multilayered folds around Gankot area are moderately flattened with mean flatting strain varying between 1.06 and 2.28. A very high degree of variation in shearing ranging about 70o in both clockwise and anticlockwise directions has been noticed. The shear strains (γ) in folds have been found to vary between -2.75 to + 3.27 with an average of +0.33. The shearing and strain patterns are suggestive that the most dominant folding mechanism has been the flexure-shear for the folds of the study area which are overprinted by the fold flattening and other subsequent deformations.

scholarly journals Geology and structural evolution in the Bheri river region, southwest Nepal

1991 ◽  
Vol 7 ◽  
Author(s):  
D. R. Kansakar
Keyword(s):  
Structural Evolution ◽  
Main Roof ◽  
Metamorphic Rocks ◽  
Lesser Himalaya ◽  
Duplex Structure ◽  
Fold Belt ◽  
Sedimentary Sequences ◽  
The North ◽  
River Region ◽  
The Himalaya

The rocks of the Lesser Himalaya in the Bheri River region have been divided into five stratigraphic groups. The meso-grade metamorphic rocks of the Chaurjhari Group is the oldest rock group in the area and is occurring as a klippen in the north. The Kunchha Group and the Nawakot Group are the incipiently metamorphosed sedimentary rocks while the Gondwana Group and Daban Group rocks are generally unmetamorphosed sedimentary sequences. In the frontal part of the thrust-fold belt of the Himalaya, leading imbricate fan structure is developed in the rocks of Daban Group with the Main Boundary Thrust (MBT) as the sole thrust, and the Kumak Thrust as the roof thrust. In the region further north, a complex of hinterland dipping duplex structure is envisioned between the Kumak Thrust (main sole thrust) and the Chaurjhari Thrust (main roof thrust) with a number of intermittent thrust-faults which acted as roof thrust to the underlying duplex and as sole thrust to the overlying duplex. The major planes of detachment for the generation of duplex are postulated along the incompetent basal rock members of the Nawakot Group, the Kunchha Group and the Chaurjhari Group respectively. As against the view of some of the earlier workers, a "piggy-back" sequence of thrust from higher to lower (hinterland towards the foreland) is proposed.

Strain analysis in composite ceramics

1986 ◽  
Vol 44 ◽  
pp. 494-497
Author(s):  
W. M. Kriven
Keyword(s):  
Strain Field ◽  
Strain Analysis ◽  
Processing Temperature ◽  
Transformation Toughening ◽  
Zirconia Ceramics ◽  
Volume Increase ◽  
Analysis Technique ◽  
Fundamental Understanding ◽  
Contrast Analysis ◽  
Elastic Strain Field

Significant progress towards a fundamental understanding of transformation toughening in composite zirconia ceramics was made possible by the application of a TEM contrast analysis technique for imaging elastic strains. Spherical zirconia particles dispersed in a large-grained alumina matrix were examined by 1 MeV HVEM to simulate bulk conditions. A thermal contraction mismatch arose on cooling from the processing temperature of 1500°C to RT. Tetragonal ZrO2 contracted amisotropically with α(ct) = 16 X 10-6/°C and α(at) = 11 X 10-6/°C and faster than Al2O3 which contracted relatively isotropically at α = 8 X 10-6/°C. A volume increase of +4.9% accompanied the transformation to monoclinic symmetry at room temperature. The elastic strain field surrounding a particle before transformation was 3-dimensionally correlated with the internal crystallographic orientation of the particle and with the strain field after transformation. The aim of this paper is to theoretically and experimentally describe this technique using the ZrO2 as an example and thereby to illustrate the experimental requirements Tor such an analysis in other systems.

Strain analysis with nanometer resolution using a conventional transmission electron microsopy technique: electron diffraction contrast imaging revisited

1995 ◽  
Vol 53 ◽  
pp. 168-169
Author(s):  
Koenraad G F Janssens ◽  
Omer Van der Biest ◽  
Jan Vanhellemont ◽  
Herman E Maes ◽  
Robert Hull
Keyword(s):  
Electron Diffraction ◽  
Strain Field ◽  
Elastic Strain ◽  
Strain Analysis ◽  
Local Strain ◽  
Contrast Imaging ◽  
Strain Characterization ◽  
Physical Mechanisms ◽  
Diffraction Contrast ◽  
Transmission Electron

There is a growing need for elastic strain characterization techniques with submicrometer resolution in several engineering technologies. In advanced material science and engineering the quantitative knowledge of elastic strain, e.g. at small particles or fibers in reinforced composite materials, can lead to a better understanding of the underlying physical mechanisms and thus to an optimization of material production processes. In advanced semiconductor processing and technology, the current size of micro-electronic devices requires an increasing effort in the analysis and characterization of localized strain. More than 30 years have passed since electron diffraction contrast imaging (EDCI) was used for the first time to analyse the local strain field in and around small coherent precipitates1. In later stages the same technique was used to identify straight dislocations by simulating the EDCI contrast resulting from the strain field of a dislocation and comparing it with experimental observations. Since then the technique was developed further by a small number of researchers, most of whom programmed their own dedicated algorithms to solve the problem of EDCI image simulation for the particular problem they were studying at the time.

Modulation of carotid strain by statin therapy in atherosclerosis patients

VASA ◽  
2017 ◽  
Vol 46 (2) ◽  
pp. 108-115 ◽  
Author(s):  
Christian Alexander Schaefer ◽  
Anna Katharina Blatzheim ◽  
Sebastian Gorgonius Passon ◽  
Kristin Solveig Pausewang ◽  
Nadjib Schahab ◽  
...  
Keyword(s):  
Statin Therapy ◽  
Pulse Wave ◽  
Ultrasound Examination ◽  
Ankle Brachial Index ◽  
Radial Strain ◽  
Strain Analysis ◽  
Duplex Ultrasound ◽  
Strain Imaging ◽  
The Common

Abstract. Background: The beneficial effect of statin therapy on the progress of atherosclerotic disease has been demonstrated by numerous studies. Vascular strain imaging is an arising method to evaluate arterial stiffness. Our study examined whether an influence of statin therapy on the vessel wall could be detected by vascular strain imaging. Patients and methods: 88 patients with recently detected atherosclerosis underwent an angiological examination including ankle-brachial index (ABI), pulse wave index (PWI), central puls ewave velocity and duplex ultrasound. Captures for vascular strain analysis were taken in B-mode during ultrasound examination of the common carotid artery and evaluated using a workstation equipped with a speckle tracking based software. A statin therapy was recommended and after six months a follow-up examination took place. Meanwhile, the non-adherence of a group of patients (N = 18) lead to a possibility to observe statin effects on the vascular strain. Results: In the statin non-adherent group the ABI decreased significantly to a still non-pathological level (1.2 ± 0.2 vs. 1.0 ± 0.2; p = 0.016) whereas it stagnated in the adherent group (1.0 ± 0.2 vs. 1.0 ± 0.2; p = 0.383). The PWI did not differ in the non-adherent group (180.5 ± 71.9 vs. 164.4 ± 75.8; p = 0.436) but under statin therapy it decreased significantly (261.8 ± 238.6 vs. 196.4 ± 137.4; p = 0.016). In comparison to the adherent group (4.2 ± 2.0 vs. 4.0 ± 1.8; p = 0.548) under statin therapy the radial strain decreased significantly in the non-adherent group (4.7 ± 2.0 vs. 3.3 ± 1.1; p = 0.014). Conclusions: Our findings reveal a beneficial influence of statin therapy on the arterial wall detected by vascular strain analysis.

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