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1

Remnant Neo-Tethyan ocean from the Ladakh Himalaya: constraints on their nature, age and tectonic setting

Talat Ahmad, Bhat Irfan, Chauhan Hiredya

Geotourism / Geoturystyka

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2023

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nr 1-2 (72-73)

11

EN

The Indus and Shyok Suture Zones represent the remnants of the Neo-Tethyan ocean in terms of Nidar arc volcanics and Zildat ophiolitic melange in the eastern Ladakh, Dras Arc volcanics and Shergol ophiolitic melange in the western Ladakh along the Indus Suture Zone. The Shyok-Nubra ophiolitic volcanics of the northern Shyok suture zone, north of the Ladakh batholith, represent the remnant northern portion of the Neo-Tethyan. The Nidar-Dras arc volcanics represent intra oceanic arc that developed as the Indian plate was moving northwards around 140 My ago. These units preserve arc tholeiite, representing primitive arc which passed on to calc alkaline series as the arc matured. These rocks are characterised by depleted nature in terms of incompatible trace elements including rare earth elements and Sm-Nd isotopic characteristics. The Zildat-Shergol ophiolitic melanges are represented by N-MORB and Ocean Island Basalt (OIB) characteristics. These units have also preserved exotic blocks of limestone, physically mixed with other units of the ophiolitic melange. The Shyok-Nubra volcanics are represented by enriched trace elements and isotopic characteristics, very different from those of the Indus Suture zone. They don’t preserve ophiolitic melange, as observed in the Indus suture zone. Our tectonic model indicate double subduction of the Neo-Tethyan ocean, in the north it got subducted under the Tibetan plate giving rise to Andean type continental arc along the Shyok suture zone. In the south the Neo-Tethyan ocean got subducted under the same oceanic crust giving rise the intra-oceanic Mariana type subduction. Thus, in the Ladakh Himalaya there is preservation of almost all components of the Neo-Tethyan ocean preserving the N-MORB and OIB type magmatism in the melange zone. The Andean and Mariana type arc components indicating very different tectonic settings. Neo-Tethyan ocean appear to have all the components that we observe presently in the Pacific-Atlantic ocean. These data will be presented and elaborated during my presentation.

2

Larger Benthic Foraminifera from Paleocene–Eocene carbonates, Eastern Tethys, Meghalaya NE India – their comparison with Western Tethys and palaeobiogeographical significance

Tewari Vinod Chandra

Geotourism / Geoturystyka

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2023

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nr 1-2 (72-73)

71--72

EN

India–Asia plate collision and uplift of the Himalaya took place during Paleocene–Eocene time (50 Ma). The extension of western Tethys Sea from Europe to Asian eastern Tethyan region has been correlated by assemblages of Larger Benthic Foraminifera (LBF). Global correlation and paleobiogeography of the eastern Meghalayan and western Tethyan Sea is discussed on the basis of SBZ of Paleocene– Eocene foraminifera assemblages (Fig. 1). Paleocene–Eocene Lakadong Limestone and Umlatodoh Limestone were deposited in shallow marine carbonate ramp depositional environment in Shillong Plateau, Meghalaya, NE India. The sedimentation basin is part of the Eastern Tethys and LBF and calcareous algae is the major carbonate facies. Coral reefs are not developed in these carbonates in contrast with the western Tethys limestones in Adriatic Platform and western European –Alpine region (Tewari et al., 2007).The LBF and algal assemblage in both the limestones is consistent with other parts of Eastern Tethys in Eastern India and Tibet (Hottinger, 1971; Scheibner & Speijer, 2008, Tewari et al., 2010). The latest Paleocene (Biozone SBZ4) miscellanids and ranikothalids are replaced by Early Eocene alveolinids and nummulitids, which dominates LBF assemblages in the western Tethyan realm at the P-E boundary (Scheibner & Speijer, 2008), Thanetian (SBZ4 Biozone) is equivalent to Tethyan platform stage II (Scheibner & Speijer, 2008). In standard biozones Ilerdian (SBZ5-SBZ6), a general reorganization in LBF communities is recorded with a long life and low reproductive potential (Hottinger, 1971). However, in the Meghalayan LBF assemblages of the lowest Eocene (biozones SBZ5/6) are still dominated by Ranikothalia and Miscellanea, while new LBFs that first emerged within this time interval elsewhere (e.g. Assilina, Alveolina and Discocyclina) are less important and Nummulites are absent. Later, in the Early Eocene there was a gradual diversification of Discocyclina and Assilina species (Fig. 1), while Ranikothalia disappeared and Miscellanea became less important by the end of the SBZ5/6 biozones. Similar LBF assemblages have been recorded in other parts of east Tethys in western India and Tibet (Scheibner & Speijer 2008; Tewari et al., 2010 and references therein). Such LBF assemblages in east Tethys thus differ from west Tethys. Palaeobiogeographical barriers must have existed between India and Eurasia during early collision of Indian Plate with Eurasia Plate around 50 Ma (Tewari et al., 2010 and references therein). These barriers prevented migration of certain LBF species of Nummulites and Alveolina between these two palaeogeographic regions. LBF dominated facies in the other basins of Meghalaya like Umlatodoh Limestone are well developed in low latitude. However, mixed coral-algal reefs and LBF facies were sparse in low-mid latitude carbonate environments (Adriatic Platform of Italy-Slovenia, Oman, Egypt, Libya, NW Somalia; Tewari et al., 2007, 2010; Scheibner & Speijer, 2008 and references therin). In contrast to west Tethys, corals are absent in Eastern Tethys (calcareous algae is present in SBZ3 and SBZ4 Biozone, Fig. 1) in the Meghalaya and other low-latitude eastern Tethys (Scheibner & Speijer, 2008). Carbonate ramp (shallow tidal flat ) carbonate environments were dominated by LBFs from Early to Late Paleocene (SBZ4, SBZ5, biozones; Fig. 1). It is interpreted that the collision of the Indian and Asian plates must have generated this difference in palaeobiodiversity by creating barriers, which prevented migration of certain LBFs (Nummulites) from west to east. Later, in the Early Eocene (SBZ6, SBZ7-SBZ8 biozones), recorded from younger Umlatodoh Limestone in the upper part gradually replaced by LBF dominated facies in the east, with highly diversified LBF species of Nummulites, Discocyclina, Discocylina jauhrii etc.), indicating stable shallow marine environmental conditions. Stable carbon and oxygen isotope analyses from Paleocene–Eocene Lakadong Limestone and Umlatodoh Limestone strongly supports a shallow marine carbonate platform deposition in Eastern Shallow Tethys, Meghalaya, India (Tewari et al., 2010)

3

Hazard estimation of Kashmir Basin, NW Himalaya using probabilistic seismic hazard assessment

Yousuf Maqbool, Bukhari Kaiser

Acta Geophysica

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2020

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Vol. 68, no. 5

1295--1316

EN

This study presents hazard estimation of Kashmir Basin, NW Himalaya using regional ground motion relations, representing one of the most seismically active region in the Himalayan belt. Fault-level seismic recurrence parameters are determined from an updated earthquake catalogue spanning from 25 to 2018 AD for all possible seismic sources. The estimated hazard maps are presented for three ground motion parameters (PGA, short and long period spectral acceleration) for 50, 100, 500 and 2500 years return periods. Moreover, uniform hazard response spectrums and hazard curves are presented for all ten districts of the basin. The southern section of the basin consisting districts of Budgam, Shopian, Pulwama and Kulgam show higher hazard levels due to presence of numerous seismogenic structures in close vicinity. Our results highlight that the imposed seismic hazard in Kashmir basin is highly underestimated which need to be redressed by modifying the current provisional design standards.

4

Estimated casualties in possible future earthquakes south and west of the M7.8 Gorkha earthquake of 2015

Wyss Max, Chamlagain Deepak

Acta Geophysica

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2019

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Vol. 67, no. 2

423--429

EN

The 2015 M7.8 Gorkha earthquake has moved the upper, unbroken, part of the Main Himalayan Thrust (MHT) and the neighboring sections of this fault closer to failure. Using the program and data set of QLARM, which has been correct in fatality estimates of past Himalayan earthquakes, we estimate quantitatively the numbers of fatalities, injured and strongly affected people when assumed ruptures along these two sections will happen. In the Kathmandu up-dip scenario with M8.1, we estimate that more than 100,000 people may perish, about half a million may be injured, and 19 million are likely to be affected strongly, if we assume the high virtual attenuation observed for the 2015 Gorkha earthquake exists here also. Likewise, if the 100 km underthrusting segment west of Gorkha ruptures, we quantitatively estimate that 12,000–62,000 people may perish and 4 million to 8 million will be strongly affected, in a down-dip (lower half of the thrust plane) and an up-dip rupture (upper half) scenario, respectively. If the up-dip part of the MHT cannot rupture by itself, and greater earthquakes are required to generate the several meters of displacement observed in trenches across the MHT, then our estimates are minima.

5

The role of orographic barriers in the origin of extreme rainfalls as exemplified by the front of high Eastern Himalaya and the low northern slope of Carpathians

Cebulak E., Gębica P., Limanówka D., Starkel L., Pyrc R.

Landform Analysis

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2018

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Vol. 36

9--17

EN

The paper discusses the role of orographic barriers in generating torrential precipitation in mountainous regions in different climatic zones, the Eastern Himalayas (tropical zone with well-developed monsoon activity) and the northern slope of the Carpathians (temperate zone with transitional climate). Attention has been paid to the different altitudes and courses of the orographic ridges as well as their location relative to the prevailing directions of influx of moist air masses. The cases analysed included torrential rains with monsoon circulation from the S–SW direction at the 2–3 km high edge of the Himalayas, with special consideration to the distance from the margin of the mountains and the exposure of the slopes. They generate frequent flood waves, landslides, debris flows and upbuilding of the alluvial cones in the foreland of the mountain barriers. The impact of the orographic barrier is significantly less marked in the Polish Carpathians. In the western part, the compact edge of the Western Beskids with an altitude of 0.5–1 km and the WSW–NEE course, exposed to moist air masses inflowing from the northern sector, is fragmented eastward into smaller mountain groups, which facilitates the penetration of moist masses of air with occurrence of prolonged precipitation into the mountains. At times, the storm cloud moves along the mountain edge (the margin of the Western Bieszczady Mts.). The marginal scarp of the Foothills has a northern exposure and a height of 150–200 m, and promotes frequent convective precipitation causing local flash floods in small streams. The cases of downpours and high discharges selected for the analysis were those for which there was available a dense network of measuring stations. An insufficient number of stations in constructing precipitation maps based on interpolation would lead to distorting the spatial image. If this were the case, then the role of slope exposure, which has an essential impact on the distribution of precipitation in mountainous regions, would be completely neglected.

6

Reservoir's impact on the water chemistry of the Teesta River mountain course (Darjeeling Himalaya)

Wiejaczka Ł., Prokop P., Kozłowski R., Sarkar S.

Ecological Chemistry and Engineering. S

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2018

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Vol. 25, nr 1

73--88

EN

The article presents the role of the newly built reservoir in the formation of the hydrochemistry of water of the Teesta River (a tributary of the Brahmaputra) in its Himalayan course. Field research were performed in the post-monsoon season of the period 2013-2015. Sampling and measuring points were located in five points over 43 km of the Teesta River in the Darjeeling Himalaya. Analysis of water along of river longitudinal profile above and below the reservoir suggest that the reservoir caused decrease most of the basic ions concentrations (Cl−, K+, Na+, Mg2+, NO3− and PO43−). An inverse trend was observed only with respect to Ca2+, SO42− and NH4+. The dam does not influent on the F− concentration. The reservoir causes minor enrichment most of the heavy metals such Cu, Ni, Zn, Cr, Cd and Sr. The lower enrichment of Teesta water below the dam indicates the water self-purification processes for metals by the Teesta Reservoir. The changes of physicochemical properties and concentrations of ions caused by the reservoir are usually normalised by environmental factors before the Teesta River outlet from the Himalayas (within 15 km of the river).

7

Site-specific Probabilistic Seismic Hazard Map of Himachal Pradesh, India. Part I. Site-specific Ground Motion Relations

Muthuganeisan P., Raghukanth S. T. G.

Acta Geophysica

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2016

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Vol. 64, no. 2

336--361

EN

This article presents four regional site-specific ground motion relations developed for the state of Himachal Pradesh in northwest Himalaya, situated in a seismically active region. These relations are developed from synthetic free surface ground motion databases obtained from a calibrated stochastic seismological model considering the characteristic properties of this specific region. The adopted methodology incorporates the site effects characterised through active MASW tests conducted in 22 important cities. The estimated ground motion levels from the developed relations are found to be in reasonable agreement with the recorded data.

8

Site-specific Probabilistic Seismic Hazard Map of Himachal Pradesh, India. Part II. Hazard Estimation

Muthuganeisan P., Raghukanth S. T. G.

Acta Geophysica

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2016

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Vol. 64, no. 4

853--884

EN

This article presents site-specific probable seismic hazard of the Himachal Pradesh province, situated in a seismically active region of northwest Himalaya, using the ground motion relations presented in a companion article. Seismic recurrence parameters for all the documented probable sources are established from an updated earthquake catalogue. The contour maps of probable spectral acceleration at 0, 0.2, and 1 s (5% damping) are presented for 475 and 2475 years return periods. Also, the hazard curves and uniform hazard response spectrums are presented for all the important cities in this province. Results indicate that the present codal provision underestimates the seismic hazard at cities of Bilaspur, Shimla, Hamirpur, Chamba, Mandi, and Solan. In addition, regions near Bilaspur and Chamba exhibit higher hazard levels than what is reported in literature

9

A geotouristic valuation of the Marsyangdi Valley in the Annapurna Himal region and its potential for the development of geotourist attractions

Łach J.

Geotourism / Geoturystyka

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2015

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nr 3-4

39--56

EN

The Marsyangdi Valley in the Annapurna Himal region is one of the most popular tourist-trekking attractions in Nepal. The performed evaluation of geotourist (geomorphological and hydrographic) objects and phenomena demonstrated a wide range of forms and, correspondingly, a huge potential for the development of geotourist attractions. The structure of The Marsyangdi Valley, which is a representative of a valley region of the High Himalaya, situated on metamorphic rocks, shows the co-existence of three major geomorphic processes: glacial, fluvial and slope, which determine specific landscape forms. Since the late 20th century, the landscape has been heavily affected by anthropogenic factors (grazing, land cultivation, settlement), reaching as far as 3500 meters above sea level, as well as by the dynamic growth and development of tourism. Expanding tourist infrastructure contributes to, inter alia, the degradation of the narrow valley bottom (tourist accommodation) and to increased mass movement on tourist trails. Despite its negative effects, tourism also exerts a positive influence on the preservation of the cultural heritage (sacred sites), which largely dominate the landscape and are a significant tourist attraction. The research was instrumental in defining the Marsyangdi Valley, characteristic of a geomorphological trail, as an excellent and qualified attraction in geotourist-exploratory tourism.

PL

Dolina Marsyangdi należąca do regionu Annapurny Himal jest jedną z najpopularniejszych atrakcji turystycznych – trekkingowych Nepalu. Przeprowadzona pod kątem obiektów i zjawisk geoturystycznych (geomorfologicznych i hydrograficznych) ocena ukazała jej dużą różnorodność form, a tym samym duży potencjał atrakcji geoturystycznych. W strukturze doliny Marsyangdi, będącej przykładem dolin obszaru Himalajów Wysokich, wyróżniono współistnienie trzech głównych procesów geomorfologicznych: glacjalnych, fluwialnych i stokowych, warunkujących specyficzne formy o wysokich walorach krajobrazowych, które od końca XX wieku podlegają szybkiej destrukcji w wyniku antropopresji. Czynniki antropogeniczne tj. hodowla, uprawa, czy osadnictwo sięgające nawet do 3500 m n.p.m., a obecnie jeszcze turystyka, przyczyniają się do wzrostu aktywności procesów geomorfologicznych m.in. ruchów masowych, w tym na szlakach turystycznych. Jednakże oprócz negatywnego wpływu turystyki na uwagę zasługuje jej pozytywne oddziaływanie w szczególności w kwestii ochrony dziedzictwa kulturowego, czego przykładem są odnawiane obiekty sakralne stanowiące niezwykłą dominantę krajobrazu oraz istotną atrakcję turystyczną. Badania pozwoliły zdefiniować obszar Doliny Marsyangdi jako odpowiedni do uprawiania turystyki kwalifikowanej, poznawczej – geoturystyki.

10

Comparison of machine learning methods for runoff forecasting in mountainous watersheds with limited data

Adamowski J., Prasher S. O.

Journal of Water and Land Development

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2012

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no. 17 [VII-XII]

89-97

EN

Runoff forecasting in mountainous regions with processed based models is often difficult and inaccurate due to the complexity of the rainfall-runoff relationships and difficulties involved in obtaining the required data. Machine learning models offer an alternative for runoff forecasting in these regions. This paper explores and compares two machine learning methods, support vector regression (SVR) and wavelet networks (WN) for daily runoff forecasting in the mountainous Sianji watershed located in the Himalayan region of India. The models were based on runoff, antecedent precipitation index, rainfall, and day of the year data collected over the three year period from July 1, 2001 and June 30, 2004. It was found that both the methods provided accurate results, with the best WN model slightly outperforming the best SVR model in accuracy. Both the WN and SVR methods should be tested in other mountainous watershed with limited data to further assess their suitability in forecasting.

PL

Prognozowanie spływu z obszarów górskich z użyciem programowanych modeli jest często trudne i niedokładne z powodu złożonych zależności między opadem a spływem i problemów związanych z pozyskaniem niezbędnych danych. Modele uczenia maszynowego stwarzają alternatywę dla prognozowania spływu z takich regionów. W pracy analizowano i porównano dwie metody uczenia maszynowego - metodę regresji wektorów nośnych (SVR) i sieci falkowych (WN) do dobowego prognozowania spływu w górskiej zlewni Sianji, usytuowanej w indyjskiej części Himalajów. Modele opracowano na podstawie danych o spływie, wskaźniku poprzednich opadów, opadzie i kolejnym dniu roku za trzyletni okres od 1 lipca 2001 r. do 30 czerwca 2004 r. Stwierdzono, że obie metody zapewniają dokładne wyniki, przy czym najlepszy model WN nieco przewyższa najlepszy model SVR pod względem dokładności. Obie metody powinny być testowane w innych zlewniach górskich o ograniczonej liczbie danych, aby lepiej ocenić ich przydatność do prognozowania.

11

Skutki globalnych zmian klimatycznych w Himalajach

Jeziorski J.

Przegląd Geologiczny

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2009

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Vol. 57, nr 7

564-565