Gravity anomaly, lithospheric structure and seismicity of Western Himalayan Syntaxis

Tiwari, V. M.; Rajasekhar, R. P.; Mishra, D. C.

doi:10.1007/s10950-008-9102-6

Cited by 21 publications

(16 citation statements)

References 20 publications

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“…It also shows high-density rocks associated with the thrusts. The hypocentres of thrust earthquakes in the 100 km-wide zone projected on this profile coincide with them and their probable extensions depth wise (Tiwari et al 2009 (Fig. 6).…”

Section: Lithospheric Density Modelmentioning

confidence: 54%

“…Effective elastic thickness (T e ) based on the coherence between the Bouguer anomaly and the topography. The best fit is obtained for T e ¼ 57 km (Tiwari et al 2009). A transition of low to high coherence is observed at a wavelength of c. 450 km, which can be interpreted as the cut-off wavelength on which compensation manifests.…”

Section: Bouguer Anomaly Mapmentioning

confidence: 85%

“…To the south of the ITSZ lies the Himalayan regime dominated by southward-verging intracrustal thrusts along which the crustal slices are exhumed and stacked together forming the Himalayan mountain belt. The loading of exhumed crustal rocks and topography flexed the Indian plate, which thickened the Indian crust towards the north, ranging from 35 to 70 km (Lyon-Caen & Molnar 1983;Tiwari et al 2006Tiwari et al , 2009Rai et al 2006;Chamoli et al 2011;Mishra et al 2012). The continued convergence of the Indian plate led to its underplating below the Tibetan slab (Li et al 2008;Zhao et al 2010).…”

Section: Regional Tectonicsmentioning

confidence: 99%

“…2). These anomalies are caused primarily due to the compensation of topography at a depth up to 70 km and are of a large wavelength in nature (Caporali 2000;Tiwari et al 2009). The causative sources of these anomalies are estimated using spectral analysis, which suggests four to five levels of sources at average depths of 127, 60, 37 and 27 km, representing the upper mantle, the Mohorovicic discontinuity (Moho), the lower crust and the upper crustal sources, respectively (Mishra et al 2012).…”

Section: Bouguer Anomaly Mapmentioning

confidence: 99%

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The lithospheric density structure below the western Himalayan syntaxis: tectonic implications

Tiwari

Mishra

Pandey

2015

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The differences in the tectonic regimes of the western part of the India -Asia collision zone (western Himalayan syntaxis), consisting of the Ladakh-Karakoram, Hindu Kush and Pamir terrains, are examined through the analyses and modelling of gravity anomalies, computed from global gravity model and terrestrial data. Long-wavelength (.450 km) anomalies are related to isostatic compensation and correspond to topographic variations. The short-wavelength gravity highs are primarily due to upthrust blocks and are mostly linked to crustal seismicity. The intermediate depth-focused earthquake region of Hindu Kush-Pamir is characterized by a gravity low probably caused by crustal underthrusting. The deep density structure of the crust and upper mantle constructed from the modelling of gravity anomalies with constraints from seismological information suggests crustal underthrusting of the Indian and the Asian plates in the Hindu Kush-Pamir section unlike that in the Ladakh-Karakoram region, where underthrust Indian lithosphere underplates beneath the Asian plate. The density model supports a hypothesis of slab breakoff of Indian and Eurasian plates in the Ladakh-Karakoram segment, and of the Indian plate in the Hindu Kush-Pamir region, whereas the Eurasian plate drastically underthrusts deeper (c. 200 km), causing deep seismicity in the Hindu Kush-Pamir section.

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Section: Lithospheric Density Modelmentioning

confidence: 54%

Section: Bouguer Anomaly Mapmentioning

confidence: 85%

Section: Regional Tectonicsmentioning

confidence: 99%

Section: Bouguer Anomaly Mapmentioning

confidence: 99%

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The lithospheric density structure below the western Himalayan syntaxis: tectonic implications

Tiwari

Mishra

Pandey

2015

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“…Gravity modeling along a profile across HKSZ (Fig. 11) shows relatively high angle subductions of the Indian and the Asian plates across the Main Karakoram Thrust and the Main Pamir Thrust, respectively compared to the east of it as described above (Kumar et al, 2005;Tiwari et al, 2008) causing fast subductions in this section. High angle subductions are usually associated with rapid rate of subduction and slab break off causing deep focus earthquakes as has been observed in case of Mariana type subductions.…”

Section: Gravity Anomalies and Deep Focus Earthquakesmentioning

confidence: 68%

Long wavelength satellite gravity and geoid anomalies over Himalaya, and Tibet: Lithospheric structures and seismotectonics of deep focus earthquakes of Hindu Kush – Pamir and Burmese arc

Mishra

Kumar

Arora

2012

Journal of Asian Earth Sciences

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Crustal study based on integrated geophysical techniques in the Northwestern Himalayas, Pakistan

2023

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The present research aims to explicate the tectonics of the northwest Himalayas, Pakistan, based on integrated gravity, magnetic and earthquake data. The raw gravity and magnetic data were processed, and seven isoanomaly maps were prepared for qualitative interpretation, whereas a gravity model was prepared along the selected profile for quantitative interpretation. The local earthquake data have also been used to identify the various seismogenic layers in the subsurface and to understand how seismicity relates to regional structural features. Three northwest-trending thickskinned blind basement faults are identified from the present study, namely the Indus Kohistan Seismic Zone (IKSZ), Bagh Basement Fault and Hazara Lower Seismic Zone. The IKSZ is the tectonically most active among them and responsible for the 2005 Kashmir earthquake (Mw = 7.6) and 1974 Pattan earthquake (Mw = 6.2) in the region. The present study also delineated the prominent location of the Main Central Thrust in which the high-grade metamorphic rocks of Higher Himalayan Crystalline thrust over low-grade metamorphic rocks of Lesser Himalayas along this thickskinned fault. The field evidence such as ductile deformation, zone of inverted metamorphism, and brittle deformation also confirm this location. The sharp bending of the crystalline crust, as well as deep basement just south of Kohistan Island Arc (KIA), indicate that the high density and susceptibility rocks of this arc thrust on the leading margin of the Indian Plate along the Main Mantle Thrust. This thrust fault is a major suture zone separating the KIA in the north from the Indian Plate in the south. The other faults in the region exist in the sedimentary/meta-sedimentary wedge and are thin-skinned. It is inferred from the current investigation that the study area exhibits a composite style of deformation. Moreover, the gravity model combined with earthquake data suggested the existence of multiple décollement zones below the Hazara-Kashmir Syntaxis. The model envisaged an increase in the thickness of the Indian Plate continental crust in the northeast direction.

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Gravity anomaly, lithospheric structure and seismicity of Western Himalayan Syntaxis

Cited by 21 publications

References 20 publications

The lithospheric density structure below the western Himalayan syntaxis: tectonic implications

The lithospheric density structure below the western Himalayan syntaxis: tectonic implications

Long wavelength satellite gravity and geoid anomalies over Himalaya, and Tibet: Lithospheric structures and seismotectonics of deep focus earthquakes of Hindu Kush – Pamir and Burmese arc

Crustal study based on integrated geophysical techniques in the Northwestern Himalayas, Pakistan

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