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, D. C.; Kumar, M. Ravi; Arora, Kusumita

doi:10.1016/j.jseaes.2011.12.003

Cited by 20 publications

(13 citation statements)

References 54 publications

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“…Nanga Parbat separates two gravity highs on the map, suggesting a north-south-orientated feature. A gravity high is also related to the Lahore -Sargodha basement ridge, which was interpreted as a flexural uplift and traced up to Delhi (Mishra et al 2012). This basement ridge is associated with the Salt Range Thrust in Pakistan, which is equivalent to the HFT in northwestern Himalaya.…”

Section: Bouguer Anomaly Mapmentioning

confidence: 95%

“…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%

“…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). The first two segments related to the upper mantle and the Moho are important as they indicate part of the subducted Indian lithosphere and crustal thickening, respectively.…”

Section: Bouguer Anomaly Mapmentioning

confidence: 99%

“…Seismicity in the Pamir -Hindu Kush belt has been attributed to the steep two-sided subduction of the Eurasian and the underthrusted Indian continental lithosphere or to a purely Eurasian origin with contortion and oversteepening of the Indian lithosphere (Sippl et al 2013). Mishra et al (2012) suggested a low density for the subducted crustal rocks as they primarily consist of the Indian/Eurasian crust and mantle lithosphere. The imprints of tectonic history are preserved in litho-tectonic units that show lateral variation in lithospheric properties.…”

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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: Bouguer Anomaly Mapmentioning

confidence: 95%

Section: Regional Tectonicsmentioning

confidence: 99%

Section: Bouguer Anomaly Mapmentioning

confidence: 99%

mentioning

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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“…Rajesh 26 , on the other hand, attributed IOGL to the presence of major density voids at depths of ~1800 km. Another study 27 proposed that IOGL results due to the accretion of lowdensity subducted Indian/Tethyan lithosphere at ~660 km discontinuity. A recent study 28 found seismic evidence for dehydrated slab graveyards above CMB beneath the Indian ocean, and linked it to IOGL.…”

Section: Geoid Anomaliesmentioning

confidence: 99%

Understanding Deep Earth Dynamics:A Numerical Modelling Approach

Singh¹,

Agrawal²,

Ghosh³

2017

Current Science

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Enhancement in computing power and better data availability have paved the way for deciphering the earth's deeper dynamics and have provided viable explanations for various surface phenomena. Tools such as seismic tomography, numerical modelling and geophysical observations such as stresses, gravity anomalies, heat flow, etc. have helped us in addressing the mechanisms of plate driving forces, anomalous geoid variations, cratonic stability, topographic support, intraplate earthquakes and similar outstanding issues in geodynamics. Due to lack of direct observations from deep earth, numerical modelling has aided considerably in learning about subsurface processes. With better algorithms being developed everyday, it is the right time to tap their potential to push the frontiers of human knowledge.

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Detailed Configuration of the Underthrusting Indian Lithosphere Beneath Western Tibet Revealed by Receiver Function Images

Zhao

Yuan

et al. 2017

JGR Solid Earth

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We analyze the teleseismic waveform data recorded by 42 temporary stations from the Y2 and ANTILOPE‐1 arrays using the P and S receiver function techniques to investigate the lithospheric structure beneath western Tibet. The Moho is reliably identified as a prominent feature at depths of 55–82 km in the stacked traces and in depth migrated images. It has a concave shape and reaches the deepest location at about 80 km north of the Indus‐Yarlung suture (IYS). An intracrustal discontinuity is observed at ~55 km depth below the southern Lhasa terrane, which could represent the upper border of the eclogitized underthrusting Indian lower crust. Underthrusting of the Indian crust has been widely observed beneath the Lhasa terrane and correlates well with the Bouguer gravity low, suggesting that the gravity anomalies in the Lhasa terrane are induced by topography of the Moho. At ~20 km depth, a midcrustal low‐velocity zone (LVZ) is observed beneath the Tethyan Himalaya and southern Lhasa terrane, suggesting a layer of partial melts that decouples the thrust/fold deformation of the upper crust from the shortening and underthrusting in the lower crust. The Sp conversions at the lithosphere‐asthenosphere boundary (LAB) can be recognized at depths of 130–200 km, showing that the Indian lithospheric mantle is underthrusting with a ramp‐flat shape beneath southern Tibet and probably is detached from the lower crust immediately under the IYS. Our observations reconstruct the configuration of the underthrusting Indian lithosphere and indicate significant along strike variations.

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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

Cited by 20 publications

References 54 publications

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

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

Understanding Deep Earth Dynamics:A Numerical Modelling Approach

Detailed Configuration of the Underthrusting Indian Lithosphere Beneath Western Tibet Revealed by Receiver Function Images

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