The Zanskar Range is unique in varied aspects and is always been an attraction to the geoscientists and tourists due to its geographic location. The most of the area and routes are not easily accessible but it is the place where the glaciers are accessible by road and hence the best place for the study on glacial geomorphology and geology. Geologically, it represents the northwestern extension of the Spiti Basin, and constitutes the southern part of the Ladakh Himalaya. This range lies between the Great Himalayan and Ladakh ranges from SW and NE. It exposes the Higher Himalayan Crystalline (HHC), Paleo-Mesozoic Tethyan Sequences, and Indus Suture Zone composed of Kargil Mollase, flysch, and ophiolitic mélange. It is an ideal field museum of young orogenic tectonic and lithological settings and faunal remains from Cambrian onwards. Sediments of the Zanskar Range show sub-vertically, tightly folded, and wedge type structures in the north and open to tight folds in the south. In the present study, we have revealed the geoheritage value of each of its exposures taking the field, areal-air, and Google traverses from Kargil to Zangla along the Suru, Shankoo, Doda, and Zanskar valleys and air traverse from Leh to Lesser Himalaya of Kashmir. It is also an ideal sequence of Quaternary glacial episodes, the natural laboratory, and the open practical school for earth scientists. Eleven geoheritage sites are proposed in the Zanskar region with several geotopes under each site, covering many potential sites of this region. In the coming days, the geopark of the Zanskar may be envisaged.

The geochemical and petrological studies were carried out to deduce the chemical composition, provenance, and intensity of chemical weathering of the source rocks in the Middle Cambrian sandstone of Spiti Basin. The petrographical studies of sandstones show texturally immature with fine to medium, angular to sub-rounded, and moderately sorted grains. The major constituent of the framework components is quartz which is majorly monocrystalline, undulatory in nature, followed by feldspar and mica with matrix. The presence of quartz grains classifies it under quartz intermediate greywacke. The studies reveal that sandstone was derived from a nearby mixed source and reflects low degree of weathering. Various weathering indices such as Chemical Index of Alteration (CIA avg. 67.24%), Plagioclase Index of Alteration (PIA avg. 75.20%), and Index of Compositional Variability (ICV avg. 1.21%) suggest low to moderate chemical weathering of the source area. The provenance discrimination based on major element concentrations indicates an intermediate and a felsic provenance for the Middle Cambrian sediments. Chondrite-normalized rare earth element (REE) patterns show enriched light rare earth element (LREE) and relatively flat heavy rare earth element (HREE) pattern with negative Eu anomaly and conclude that the sediments were derived from felsic source. The major element–based discrimination diagrams suggest active marginal setting to the studied sediments.

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The Tethyan sedimentary sequences is traced along the entire length of the Himalaya and preserves one of the most well defined and classical sections of Palaeozoic and Mesozoic lithostratigraphic units with diverse fossil record. The deposition of marine sediments of the Phanerozoic Eon was mostly restricted to Tethyan Himalayan regions. The Phanerozoic successions of Tethys Himalaya are well developed in three basins viz. Kashmir, Spiti-Zanskar and Kumaun-Garhwal. In the past few decades, several studies have improved our understanding in stratigraphy, fauna, and age of the Phanerozoic Tethyan sequences of the North-western Himalaya. Several studies have proposed various stratigraphic names and independent stratigraphic schemes on Tethyan sequences of North-western Himalaya. This review compile data for the Kashmir, Spiti-Zanskar and Kumaun Garhwal basins and present basin-wise descriptions of different lithostratigraphic units and their faunal elements in space and time. The stratigraphic schemes presented here may have significant implications for future investigations.

Sedimentary rocks from the Himalayas are well-preserved archives of the Neo-Tethys oceanic conditions. In this contribution, Re–Os isotopic systematics of black shales from the Gungri Formation, Spiti valley and siltstones from the Khunamuh Formation, Guryul Ravine have been investigated to constrain their depositional ages. The Re–Os isochron for the Gungri shales yields a depositional age of 255 ± 22 Ma (2σ; n = 8; MSWD (Mean Square Weighted Deviation) = 5.7), consistent with available biostratigraphic information. The initial 187Os/188Os ratio (0.60 ± 0.13) is similar to that reported for the Late Permian shales, indicating the connection of the Neo-Tethys with the global ocean. In contrast, the Re–Os systematic is found to be non-isochronous for the Guryul Ravine section, a proximal site with a strong influence of seismic/Tsunami events. Global compilation of 187Re/188Os ratios in Late Permian shales and bathymetric distribution of the Re/Os ratios point to strong role of Re/Os uptake by macroalgae, in addition to oceanic pH and redox state, in regulating the Re–Os systematic in shales. The 87Sr/86Sr ratios for the Induan carbonates from the Spiti (0.71551–0.71837) are higher than to that expected for the Lower Triassic ocean (~0.707). Co-variations of Sr and 87Sr/86Sr with Mn concentrations establish the diagenetic alteration of these carbonates.

The petrography and geochemistry of the siliciclastic rocks of Batal Formation, Spiti Basin were studied to define the provenance, tectonic setting, and depositional environment. Petrographical studies show that the percentage of quartz in sandstone varies from 70 to 80%, whereas in siltstone and shale, it varies from 50 to 60%. Similar pattern of chondrite-normalized REE, with enriched LREE, depleted HREE, and a negative Eu anomaly, suggests that the source rock is of felsic type. Significant correlation between Zr versus Yb and ΣHREE indicates that these sediments are influenced by sediment recycling. The Ni/Co and Cu/Zn ratios suggest that sediments were deposited under low to moderate oxygenated conditions, while the CIA values and A-CN-K plot reflect moderate to intense weathered source area with the presence of clay minerals derived during the cold period. The major element–based multidimensional tectonic discrimination diagrams suggest an active marginal setting for the sediments of Batal Formation. Further, the discrimination diagrams equally suggest that these sediments were derived from sedimentary provenance and to some extent from the felsic igneous provenance.

The geochemical study of siliciclastic rocks from the Lower Cambrian of Parahio Valley has been studied to describe the provenance, chemical weathering and tectonic setting. The K2O/Al2O3 ratio and positive correlation of Co (r=0.85), Ni (r=0.86), Zn (r=0.82), Rb (r=0.98) with K2O reflects that the presence of clay minerals control the abundances of these elements and suggests a warm and humid climate for this region. The chondrite normalized REE pattern of the samples is equivalent to upper continental crust, which reflects enriched LREE and flat HREE with negative Eu anomaly. The tectonic setting discriminant diagram log[K2O/Na2O] vs. SiO2; [SiO2/Al2O3] vs. log[K2O/Na2O]; [SiO2/20] – [K2O+Na2O] – [TiO2+Fe2O3+MgO] indicates transitional tectonic setting from an active continental margin to a passive margin. The discriminant function plot indicates quartzose sedimentary provenance, and to some extent, the felsic igneous provenance, derived from weathered granite, gneissic terrain and/or from pre-existing sedimentary terrain. The CIA value indicates low to moderate degree of chemical weathering and the average ICV values suggests immature sediments deposited in tectonically active settings. The A–CN–K diagram indicates that these sediments were generated from source rocks of the upper continental crust.

Trace fossils and microbially induced sedimentary structures are documented from the Early Cambrian succession of the Chandratal section in the Spiti Basin for the first time. The marine succession contains different trace fossil assemblages representing mainly horizontal and branched structures that mostly belong to arthropods, annelids and polychaets. The trace fossils include Chondrites, Dimorphichnus, Diplichnites, Monomorphichnus Palaeophycus, Planolites, and Skolithos along with some burrows and scratch marks. These trace fossils are preserved in shale, siltstone and sandstone, whereas microbially induced structures are preserved below the trace-fossil horizon in fine-grained sandstone. Microbially induced sedimentary structures occur in patches on the bedding planes. The described trace fossils reflect the presence of suspension and deposit feeding animals in response to changing environmental conditions. Their complexity signifies environments oscillating between subtidal and intertidal. In the basal unit of succession, the presence of microbially induced mats in the fine-grained sandstone indicates lack of grazing activity of organisms and a shallow marine environment within photic zone.

During the period 2011-2015, scientific investigations in the Himalaya incorporated various geological and geophysical aspects of evolution of this mountain, including sub-surface configuration, structure and metamorphism of the Lesser Himalaya and Himalayan Metamorphic Belt, geochemistry, magmatism, stratigraphy and paleontology of the Paleo-Mesozoic Tethyan sedimentary cover, the Himalayan foreland basins, exhumation, paleoseismology and GPS measurements of convergence rates.Certain remote areas of western Arunachal Pradesh in Kameng were covered for their metamorphism and exhumation.Sm-Nd isochron plot of garnet crystals from the Lesser Himalayan Jutogh Group metamorphics provided a mean regression age of 479.7±8.5 Ma as the timing of its crystallization during an Early Ordovician tectonometamorphic event.High-resolution work on metamorphism of the Lesser and Higher Himalayan belts of Sikkim incorporating P-T-t paths and geochronology of the imbricate zones of the Main Central Thrust provided better insight into their evolution.

The Indus Group succession of Ladakh represents the final phase of deposition in the Indus Tsangpo Suture Zone (ITSZ; also referred to as the Indus Suture Zone), before the final uplift of the Himalaya. These sediments were deposited in an actively subsiding basin (Indus Basin), formed after the India-Asia collision, developed over forearc and related basins. The Indus Basin represents a narrow embayment occupied by a relict shallow sea with prominent tidal energy. It received sediments from the north (Ladakh Batholith and Karakoram block) as well as the south (Indian continental margin and Suture zone deposits). During its deposition, tectonic pulses in the north as well as the south contributed coarse sediments in the form of conglomerates. The deposition in the basin took place in a tidal flat and sand-shoal complexes under the influence of moderate tidal energy and weak wave energy. In the areas of point sources in the basin, alluvial fans built braid plains extending into the basin. The basin closed in the east due to collision of Indian and Myanmarese (Burmese) plates; however, in the west it was open, connected to a diminishing Neotethys Ocean. In Pakistan, marine influences are prominent. The Indus Basin received huge amounts of freshwater and detritus from landmasses in the north and the south. Most of the fossil records in the Indus Group are freshwater plants, land vertebrates, freshwater molluscs and ostracods from the conglomerate deposits of the braid plain. The age of the Indus Group sediments is estimated to be from 41 Ma to 20 Ma, though no precicise biostratigraphic and chronostratigraphic control is available. Inversion of basin resulted in upliftment of sediment over the Ladakh Batholith around 20 Ma. Deposition in the Indus Group is almost contemporary with the deposition of the Sirmur Group (particularly the Dagsai-Kasauli formations) of the Lesser Himalaya. It is postulated that deposition in both the areas was controlled by same geotectonic processes of the Himalaya.

The Middle Cambrian succession of the Parahio Valley in general and Debsakhad section in particular is dominated by trilobites. Genus Opsidiscus, along with other trilobite forms dominates the lower Middle Cambrian succession. In the present study two new species of Opsidiscus, Opsidiscus wadiai and Opsidiscus srikantiai are reported from the lower Middle Cambrian succession of Debsakhad section. The species were differentiated on their morphological features and their multivariate analysis. The multivariate analysis applied here is used as a supplement method to qualitative analysis in order to differentiate between the cranidial characters of Opsidiscus. The qualitative study of each species studied individually shows more or less close affiliation as is observed by different quantitative methods. The presence of Opsidiscus has a great stratigraphic significance in this region, as they first appear from informal Stage 5 of Series 3 and goes up to the Drumian Stage of Series 3 of the Cambrian System in the Debsakhad section, which helps to correlate this section with other well known sections of the Middle Cambrian.

The Lesser Himalayan sequence is considered as one of the best developed sections of Cambrian successions, exposed in five different synclines. Mussoorie Syncline, being one of the five synclines, exposes the Cambrian Tal Group. This paper describes nine ichnotaxa, viz., Dimorphichnus isp., ?Diplichnites isp., Monomorphichnus isp., Nereites isp., Palaeopasichnus isp., Palaeophycus isp., Planolites montanus, Planolites isp., Skolithos isp., Treptichnus isp. from the Dhaulagiri Formation of the Tal Group. A detailed analysis of the ichnofossils indicates that the entire succession of Tal Group reflects shallow marine conditions in general and Mussoorie Syncline in particular. The above ichnofossil assemblage along with earlier ichnofossils and other faunal occurrences substantiates the assignment of Early Cambrian age to the Dhaulagiri Formation.

Well preserved trace fossils produced by trilobites are reported from the outcrops of the Tethyan Kunzum La Formation exposed, near the Lal Devta Temple, along the Jadhganga River Valley in Uttarkashi District of NW Himalaya. The trace fossils are preserved in medium to fine grained, brown-buff to greenish coloured sandstone and siltstone beds having thin partings of light brown coloured argillaceous matter. The trace fossils are Dimorphichnus isp. and Rusophycus isp. along with Cruziana and worm tracks. These traces are ascribed to the life activity of trilobites in a shallow marine environment during Early Cambrian time. Thus the present finding suggest an Early Cambrian age for the trace fossil bearing outcrops of the Kunzum La Formation exposed along the Jadhganga River in Garhwal Tethys Himalaya and could be correlated with the similar outcrops exposed in the Salt Range and elsewhere in the NW Tethys and the Lesser Himalayan realm.

The Spiti Basin exposes well preserved Cambrian successions in the Tethys Himalaya. The present ichnofossil assemblage is reported from the Debsakhad Member of the Kunzum La Formation. The ichnofossils includes the ichnogenera Bergaueria, Chondrites, Cruziana, Didymaulichnus, Dimorphichnus, Diplichnites, Helminthorhaphe, Merostomichnites, ?Monocraterion, Monomorphichnus, Nereites, Palaeopascichnus, Palaeophycus, Phycodes, Planolites, Rusophycus, Skolithos, Scolicia, Treptichnus, etc. along with annelid worm, burrow and scratch marks. These ichnogenera can be assigned to cubichnial, repichnial, pascichnial to fodinichnial behaviors. The ichnofossils reported from this section provide evidence regarding the developmental patterns during the early phase of life. In absence of trilobites, the present assemblage of ichnofossils is very significant in assigning the age of the Debsakhad Member. The abundance of ichnofossils in sandstone, siltstone and in shale beds indicate that the ichnocenosis is dominated by a high behavioral diversity ranging from the suspension to deposit feeders. Three lithofacies were observed in this section, they show a vertical disposition, which further reflects general upward coarsening trend. Ichnofossils are mostly produced by arthropods along with crustacean, polychaetes and polyphyletic vermiforms. Due to the paucity of body fossil, as well as microbiota in the lowermost beds of the Debsakhad Member, the Precambrian–Cambrian boundary could not be demarcated. However, the presence of Treptichnus and Phycodes can be considered as a horizon marker for the beginning of Lower Cambrian in this section.

The Muth Formation is one of the most characteristic marker horizon traced throughout the northwestern Himalaya. The present studies were carried out in the Farakah Muth (Pin Valley) section of Spiti Basin. The formation uniformly consists of quartzarenite with a high textural and compositional maturity. The development of carbonate beds in the upper part of the Muth Formation separates it conformably from the overlying Lipak Formation. A variety of traces were observed throughout the succession, includes: Metaichna, Planolites, Skolithos , vertical and horizontal burrows. The presence of ichnofossils in the Muth Formation of the Farakah section indicates subtidal settings having soft sandy substrate, whereas, the gradual maturity of the quartz grains from base to top indicates deposition under high energy condition.