scholarly journals Orogenic Segmentation and Its Role in Himalayan Mountain Building

2021 ◽  
Vol 9 ◽  
Author(s):  
Mary Hubbard ◽  
Malay Mukul ◽  
Ananta Prasad Gajurel ◽  
Abhijit Ghosh ◽  
Vinee Srivastava ◽  
...  
Keyword(s):  
Continental Collision ◽  
Large Contribution ◽  
The Tibetan Plateau ◽  
Thrust Belt ◽  
The North ◽  
Mountain Front ◽  
Mountain Belts ◽  
Basement Structures ◽  
Lateral Variations ◽  
The Himalaya

The continental collision process has made a large contribution to continental growth and reconfiguration of cratons throughout Earth history. Many of the mountain belts present today are the product of continental collision such as the Appalachians, the Alps, the Cordillera, the Himalaya, the Zagros, and the Papuan Fold and Thrust Belt. Though collisional mountain belts are generally elongate and laterally continuous, close inspection reveals disruptions and variations in thrust geometry and kinematics along the strike of the range. These lateral variations typically coincide with cross structures and have been documented in thrust fault systems with a variety of geometries and kinematic interpretations. In the Himalaya, cross faults provide segment boundaries that, in some cases separate zones of differing thrust geometry and may even localize microseismicity or limit areas of active seismicity on adjacent thrust systems. By compiling data on structural segmentation along the length of the Himalayan range, we find lateral variations at all levels within the Himalaya. Along the Gish fault of the eastern Indian Himalaya, there is evidence in the foreland for changes in thrust-belt geometry across the fault. The Gish, the Ganga, and the Yamuna faults all mark boundaries of salients and recesses at the mountain front. The Benkar fault in the Greater Himalayan sequence of eastern Nepal exhibits a brittle-ductile style of deformation with fabric that crosscuts the older thrust-sense foliation. Microseismicity data from several regions in Nepal shows linear, northeast-striking clusters of epicenters sub-parallel to cross faults. The map pattern of aftershock data from the 2015 Nepal earthquakes has an abrupt northeast-trending termination on its eastern side suggesting the presence of a structure of that orientation that limited slip. The orientations of the recognized cross faults and seismic patterns also align with the extensional zones to the north on the Tibetan Plateau and the Indian basement structures to the south. Results from multiple studies are consistent with a link between cross faults and either of these structural trends to the north or south and suggest that cross faults may play a role in segmenting deformation style and seismic activity along the length of the Himalaya.

scholarly journals Glacier variations in the Himalaya from 1990 to 2015 based on remote sensing

2020 ◽  
Author(s):  
Qin Ji ◽  
Jun Dong ◽  
Hong-rong Li ◽  
Yan Qin ◽  
Rui Liu ◽  
...  
Keyword(s):  
Spatial Scales ◽  
Mountain Range ◽  
The Tibetan Plateau ◽  
Large Area ◽  
Glacier Inventory ◽  
The North ◽  
South Slope ◽  
Monsoon System ◽  
The Himalaya ◽  
Continental Climate

Abstract. The Himalaya is located in the southwest margin of the Tibetan Plateau. The region is of special interest for glacio-climatological research as it is influenced by both the continental climate of Central Asia and The Indian Monsoon system. Despite its large area covered by glaciers, detail glacier inventory data are not yet available for the entire Himalaya. The study presents spatial patterns in glacier area in the entire Himalaya are multiple spatial scales. We combined Landsat TM/ETM+/OLI from 1990 to 2015 and ASTER GEDM (30 m). In the years around 1990 the whole mountain range contained about 12211 glaciers covering an area of 23229.27 km2, while the ice on south slope covered 14451.25 km2. Glaciers are mainly distributed in the western of the Himalaya with an area of 11551.69 km2 and the minimum is the eastern. The elevation of glacier mainly distributed at 4,800∼6,200 m a.s.l. with an area percent of approximately 84 % in 1990. The largest number and ice cover of glaciers is hanging glacier and valley glacier, respectively. The number of debris-covered glaciers is relatively small, whereas covers an area of about 44.21 % in 1990. The glacier decreased by 10.99 % and this recession has accelerated from 1990 to 2015. The average annual shrinkage rate of the glaciers on the north slope (0.54 % a−1) is greater than that on the south slope (0.38 % a−1). Glacier decreased in the debris-covered glaciers and debris-free glaciers, and the area loss for the first is about 15.56 % and 5.22 % for the latter during 1990–2015, which showed that the moraine in the Himalaya can inhibit the ablation of glaciers to some extent.

The 2020 Mw 6.0 Jiashi Earthquake: Coinvolvement of Thin-Skinned Thrusting and Basement Shortening in Shaping the Keping-Tage Fold-and-Thrust Belt in Southwestern Tian Shan

2021 ◽  
Author(s):  
Yuqing He ◽  
Teng Wang ◽  
Lihua Fang ◽  
Li Zhao
Keyword(s):  
Surface Deformation ◽  
Reverse Fault ◽  
Thrust Belt ◽  
Coulomb Stress Changes ◽  
The North ◽  
Fold And Thrust Belt ◽  
Stress Changes ◽  
Mountain Front ◽  
Tear Fault ◽  
Tian Shan

Abstract The Keping-tage fold-and-thrust belt in southwest Tian Shan is seismically active, yet the most well-recorded earthquakes occurred south of the mountain front. The lack of large earthquakes beneath the fold-and-thrust belt thus hinders our understanding of the orogenic process to the north. The 2020 Mw 6.0 Jiashi earthquake is an important event with surface deformation in the fold-and-thrust belt well illuminated by Interferometric Synthetic Aperture Radar, providing an opportunity to study the present-day kinematics of the thrust front through the analysis of satellite measurements of surface deformations. Here, we employ the surface deformation and relocated aftershocks to investigate the fault-slip distribution associated to this event. Further added by an analysis of Coulomb stress changes, we derive a fault model involving slips on a shallow, low-angle (∼10°) north-dipping thrust fault as well as on a left-lateral tear fault and a high-angle south-dipping reverse fault in mid-crust. Aftershocks at depth reflect the basement-involved shortening activated by a thin-skinned thrust faulting event. In addition, this earthquake uplifted the southernmost mountain front with relatively low topography, indicating the basin-ward propagation of the southwest Tian Shan.

Protracted continental collision — evidence from the Grenville OrogenThis article is one of a series of papers published in this Special Issue on the theme Lithoprobe — parameters, processes, and the evolution of a continent.

2010 ◽  
Vol 47 (5) ◽  
pp. 591-620 ◽  
Author(s):  
Andrew Hynes ◽  
Toby Rivers
Keyword(s):  
Continental Margin ◽  
Regional Metamorphism ◽  
Granulite Facies ◽  
Continental Collision ◽  
Northwestern Part ◽  
Grenville Province ◽  
The North ◽  
Laurentian Margin ◽  
Lower Crustal ◽  
The Himalaya

The Grenville Orogen in North America is interpreted to have resulted from collision between Laurentia and another continent, probably Amazonia, at ca. 1100 Ma. The exposed segment of the orogen was derived largely from reworked Archean to Paleoproterozoic Laurentian crust, products of a long-lived Mesoproterozoic continental-margin arc and associated back arc, and remnants of one or more accreted mid-Mesoproterozoic island-arc terranes. A potential suture, preserved in Grenvillian inliers of the southeastern USA, may separate rocks of Laurentian and Amazonian affinities. The Grenvillian Orogeny lasted more than 100 million years. Much of the interior Grenville Province, with peak metamorphism at ca. 1090–1020 Ma, consists of uppermost amphibolite- to granulite-facies rocks metamorphosed at depths of ca. 30 km, but areas of lower crustal, eclogite-facies nappes metamorphosed at 50–60 km depth also occur and an orogenic lid that largely escaped Grenvillian metamorphism is preserved locally. Overall, deformation and regional metamorphism migrated sequentially to the northwest into the Laurentian craton, with the youngest contractional structures in the northwestern part of the orogen at ca. 1000–980 Ma. The North American lithospheric root extends across part of the Grenville Orogen, where it may have been produced by depletion of sub-continental lithospheric mantle beneath the long-lived Laurentian-margin Mesoproterozoic subduction zone. Both the Grenville Orogen and the Himalaya–Tibet Orogen have northern margins characterized by long-lived subduction before continental collision and protracted convergence following collision. Both exhibit cratonward-propagating thrusting. In the Himalaya–Tibet Orogen, however, the pre-collisional Eurasian-margin arc is high in the structural stack, whereas in the Grenville Orogen, the pre-collisional continental-margin arc is low in the structural stack. We interpret this difference as due to subduction reversal in the Grenville case shortly before collision, so that the continental-margin arc became the lower plate during the ensuing orogeny. The structurally low position of the warm, extended Laurentian crust probably contributed significantly to the ductility of lower and mid-crustal Grenvillian rocks.

scholarly journals Variable Thrust Rates of the Eastern Qilianshan Mountain Front, Northeastern Margin of the Tibet Plateau and Its Implication to the Topography of the Yongchangnan Shan

2021 ◽  
Vol 9 ◽  
Author(s):  
Lei Jinghao ◽  
Li Youli ◽  
Ren Zhikun ◽  
Hu Xiu ◽  
Xiong Jianguo ◽  
...  
Keyword(s):  
Slip Rate ◽  
Strike Slip ◽  
Tibet Plateau ◽  
The Tibetan Plateau ◽  
The West ◽  
Slip Rates ◽  
Study Region ◽  
The North ◽  
Mountain Front ◽  
The Tibet Plateau

It is commonly assumed a thrust has a constant slip and uplifting rate along strike, however, this simplified model cannot always be consistent with field observations. The along strike slip patterns with variable offsets and rates contain plenty of information about the characteristics of the faulting behavior and its relationship with adjacent faults. The east Qilian Shan, located at the northeastern margin of the Tibetan Plateau, provides us an excellent opportunity to study the faulting behavior in a thrust-bounded range area. Besides the previously reported slip rates of the N-W trending tectonics across the region, we augmented the data by surveying the Fengle fault (FF), one of the north bounding thrusts of the Yongchangnan Shan. Another north bounding fault is the Kangningqiao Fault (KNF), east of the FF. Based on the vertical offsets and rates along the fault, we constructed the slip pattern along strike. The results show the vertical slip rate of the FF ranges from 0.7 ± 0.1 mm/a to 2.8 ± 1.3 mm/a across three surveyed sites. The slip rate decreases from the east to the west. The FF and KNF might be inferred as two segments of a single segmented thrust controlling the uplift of the Yongchangnan Shan. By comparing the uplift onsets in the study region, we discuss the northeastward propagated deformation along the northeastern margin of the Tibet plateau.

Reconciling plate convergence and orogeny: The influence of India-Asia convergence rate on the formation of the Himalayas

2020 ◽  
Author(s):  
Ben S. Knight ◽  
Fabio A. Capitanio ◽  
Roberto F. Weinberg
Keyword(s):  
Tibetan Plateau ◽  
Numerical Models ◽  
The Tibetan Plateau ◽  
Thrust Belt ◽  
Plate Convergence ◽  
Structural Style ◽  
Fold And Thrust Belt ◽  
Velocity History ◽  
The Himalaya

<p>The collision of India and Eurasia since ~50 Ma has resulted in a broad range of deformation along the Himalaya-Tibetan orogeny, accommodating >2700 km of convergence. The region is characterised by the Tibetan Plateau, the Himalayan internal units and fold-and-thrust belt from North to South. These formed as a consequence of a convergence history characterised by a progressive decrease in velocity, from ~10 cm/yr 50 Ma, to ~8 cm/yr 42.5 Ma and to present-day values of ~4 cm/yr around 20 Ma. Here, we test the controls of such a convergence velocity history on the orogeny of a viscoplastic wedge during collision, above a subducting continental lithosphere. We compare numerical models simulating India-Asia plate convergence and collision, comparing the structures observed throughout the evolution with those observed in the Himalayan-Tibetan region. The models display distinct phases of growth and structural style evolution in the Himalayan-Tibetan region that are a result of the change in convergence velocity and long-term collision. After an initial stacking, the high convergence velocity forces deformation migration towards the upper plate, where a plateau forms, while late stage slowdown of collision favours the formation of the Himalayan fold-and-thrust belt. While the latter is in agreement with the structuring of the southermost domains and the South Tibetan Detachment (STD) fault, the former provide constraints to the initial uplift of the Tibetan Plateau.</p>

Preliminary detrital zircon U-Pb Geochronology of the Wasatch Formation, Powder River Basin, Wyoming

2019 ◽  
Vol 56 (3) ◽  
pp. 247-266
Author(s):  
Ian Anderson ◽  
David H. Malone ◽  
John Craddock
Keyword(s):  
River Basin ◽  
Detrital Zircon ◽  
Middle Part ◽  
Detrital Zircons ◽  
Powder River Basin ◽  
Zircon Age ◽  
Lower Eocene ◽  
The North ◽  
Mountain Front ◽  
Fluvial Sandstone

The lower Eocene Wasatch Formation is more than 1500 m thick in the Powder River Basin of Wyoming. The Wasatch is a Laramide synorgenic deposit that consists of paludal and lacustrine mudstone, fluvial sandstone, and coal. U-Pb geochronologic data on detrital zircons were gathered for a sandstone unit in the middle part of the succession. The Wasatch was collected along Interstate 90 just west of the Powder River, which is about 50 km east of the Bighorn Mountain front. The sandstone is lenticular in geometry and consists of arkosic arenite and wacke. The detrital zircon age spectrum ranged (n=99) from 1433-2957 Ma in age, and consisted of more than 95% Archean age grains, with an age peak of about 2900 Ma. Three populations of Archean ages are evident: 2886.6±10 Ma (24%), 2906.6±8.4 Ma (56%) and 2934.1±6.6 Ma (20%; all results 2 sigma). These ages are consistent with the age of Archean rocks exposed in the northern part of the range. The sparse Proterozoic grains were likely derived from the recycling of Cambrian and Carboniferous strata. These sands were transported to the Powder River Basin through the alluvial fans adjacent to the Piney Creek thrust. Drainage continued to the north through the basin and eventually into the Ancestral Missouri River and Gulf of Mexico. The provenance of the Wasatch is distinct from coeval Tatman and Willwood strata in the Bighorn and Absaroka basins, which were derived from distal source (>500 km) areas in the Sevier Highlands of Idaho and the Laramide Beartooth and Tobacco Root uplifts. Why the Bighorn Mountains shed abundant Eocene strata only to the east and not to the west remains enigmatic, and merits further study.

Size distribution of PM20 observed to the north of the Tibetan Plateau

2021 ◽  
Vol 18 (2) ◽  
pp. 367-376
Author(s):  
Cheng-long Zhou ◽  
Fan Yang ◽  
Wen Huo ◽  
Ali Mamtimin ◽  
Xing-hua Yang
Keyword(s):  
Tibetan Plateau ◽  
Size Distribution ◽  
The Tibetan Plateau ◽  
The North

A review of the tectonics of the northern Middle East region

1984 ◽  
Vol 121 (6) ◽  
pp. 577-587 ◽  
Author(s):  
P. E. R. Lovelock
Keyword(s):  
Late Cretaceous ◽  
Kinematic Model ◽  
Continental Collision ◽  
Dead Sea ◽  
Plate Motion ◽  
Arabian Plate ◽  
Southern Boundary ◽  
The North ◽  
The Dead ◽  
Two Stages

AbstractThe structure of the northern part of the Arabian platform is reviewed in the light of hitherto unpublished exploration data and the presently accepted kinematic model of plate motion in the region. The Palmyra and Sinjar zones share a common history of development involving two stages of rifting, one in the Triassic–Jurassic and the other during late Cretaceous to early Tertiary times. Deformation of the Palmyra zone during the Mio-Pliocene is attributed to north–south compression on the eastern block of the Dead Sea transcurrent system which occurred after continental collision in the north in southeast Turkey. The asymmetry of the Palmyra zone is believed to result from northward underthrusting along the southern boundary facilitated by the presence of shallow Triassic evaporites. An important NW-SE cross-plate shear zone has been identified, which can be traced for 600 km and which controls the course of the River Euphrates over long distances in Syria and Iraq. Transcurrent motion along this zone resulted in the formation of narrow grabens during the late Cretaceous which were compressed during the Mio-Pliocene. To a large extent, present day structures in the region result from compressional reactivation of old lineaments within the Arabian plate by the transcurrent motion of the Dead Sea fault zone and subsequent continental collision.

scholarly journals Precipitation and snow cover in the Himalaya: from reanalysis to regional climate simulations

2013 ◽  
Vol 17 (10) ◽  
pp. 3921-3936 ◽  
Author(s):  
M. Ménégoz ◽  
H. Gallée ◽  
H. W. Jacobi
Keyword(s):  
Snow Cover ◽  
Climate Model ◽  
Regional Climate ◽  
Rain Gauge ◽  
Snow Accumulation ◽  
The Tibetan Plateau ◽  
Monsoon Period ◽  
Medium Range Weather Forecast ◽  
Snow Cover Extent ◽  
The Himalaya

Abstract. We applied a Regional Climate Model (RCM) to simulate precipitation and snow cover over the Himalaya, between March 2000 and December 2002. Due to its higher resolution, our model simulates a more realistic spatial variability of wind and precipitation than those of the reanalysis of the European Centre of Medium range Weather Forecast (ECMWF) used as lateral boundaries. In this region, we found very large discrepancies between the estimations of precipitation provided by reanalysis, rain gauges networks, satellite observations, and our RCM simulation. Our model clearly underestimates precipitation at the foothills of the Himalaya and in its eastern part. However, our simulation provides a first estimation of liquid and solid precipitation in high altitude areas, where satellite and rain gauge networks are not very reliable. During the two years of simulation, our model resembles the snow cover extent and duration quite accurately in these areas. Both snow accumulation and snow cover duration differ widely along the Himalaya: snowfall can occur during the whole year in western Himalaya, due to both summer monsoon and mid-latitude low pressure systems bringing moisture into this region. In Central Himalaya and on the Tibetan Plateau, a much more marked dry season occurs from October to March. Snow cover does not have a pronounced seasonal cycle in these regions, since it depends both on the quite variable duration of the monsoon and on the rare but possible occurrence of snowfall during the extra-monsoon period.

scholarly journals Recording microscale variations in snowpack layering using near-infrared photography

2010 ◽  
Vol 56 (195) ◽  
pp. 75-80 ◽  
Author(s):  
Ken D. Tape ◽  
Nick Rutter ◽  
Hans-Peter Marshall ◽  
Richard Essery ◽  
Matthew Sturm
Keyword(s):  
Near Infrared ◽  
Digital Camera ◽  
Post Processing ◽  
Snow Layer ◽  
Avalanche Forecasting ◽  
The North ◽  
Nir Imaging ◽  
Snow Stratigraphy ◽  
Wind Events ◽  
Lateral Variations

AbstractDeposition of snow from precipitation and wind events creates layering within seasonal snowpacks. The thickness and horizontal continuity of layers within seasonal snowpacks can be highly variable, due to snow blowing around topography and vegetation, and this has important implications for hydrology, remote sensing and avalanche forecasting. In this paper, we present practical field and post-processing protocols for recording lateral variations in snow stratigraphy using near-infrared (NIR) photography. A Fuji S9100 digital camera, modified to be sensitive to NIR wavelengths, was mounted on a rail system that allowed for rapid imaging of a 10 m long snow trench excavated on the north side of Toolik Lake, Alaska (68°38′ N, 149°36′ W). Post-processing of the images included removal of lens distortion and vignetting. A tape measure running along the base of the trench provided known locations (control points) that permitted scaling and georeferencing. Snow layer heights estimated from the NIR images compared well with manual stratigraphic measurements made at 0.2 m intervals along the trench (n = 357, R2 = 0.97). Considerably greater stratigraphic detail was captured by the NIR images than in the manually recorded profiles. NIR imaging of snow trenches using the described protocols is an efficient tool for quantifying continuous microscale variations in snow layers and associated properties.

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