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Protracted interseismic locking of the low‐angle décollement of the Himalaya causes strain accumulation and results in growing slip deficit with time. Unlocking the frontal splay of the décollement during high‐magnitude earthquakes (Mw ≥6.5) may cause surface ruptures along the Himalayan Frontal Thrust (HFT). According to Paleoseismic investigations and observations on undeformed fluvial strath surfaces, the HFT in Nahan Salient has not experienced coseismic slip at least for the last six to seven centuries. Our new observations and chronological assessments on folded and faulted fluvial strath surfaces on the hanging wall of the HFT indicates a maximum slip rate of 10.4 ± 0.8–12.2 ± 0.8 mm/a (averaged over the last 7–8 ka). Seismic quiescence of 600–700 a results in a ~6.2–8.5 m slip deficit on the HFT which could trigger a Mw ≥7.7 earthquake. Our findings underline an enormous seismic risk prevailing in the Nahan area. [ABSTRACT FROM AUTHOR]

Sediment transfer from the interiors of the Himalaya is complex because the archives are influenced by both glacial and monsoonal cycles. To deconvolve the coupling of glacial and monsoonal effects on sediment transfer processes, we investigate the Late Pleistocene–Holocene sediment archive in the Upper Chenab valley. Optically stimulated luminescence (OSL) ages from the archive indicate major aggradation during ca. 20–10 ka. Isotopic fingerprinting using Sr-Nd isotopes in silt fractions together with clast counts in boulder-pebble fractions indicate a decreasing Higher Himalayan sediment flux in the archive with time. Decreasing clast size, increasing clast roundness, increasing matrix to clast ratio, and dominance of the Higher Himalayan sourcing unequivocally suggest strong glacial influence during the initial stages of the archive formation. This evidence also agrees with the existing retreat ages of glaciers in the Upper Chenab valley. Results of our study also show that the upper parts of the archive contain significant fluvial sediment contribution from the Lesser Himalaya, which suggests an active role of the stronger Indian Summer Monsoon (ISM) in the region during the Early Holocene. The apparent decrease in sediment supply from the Higher Himalayan sources could have been due to longer source-to-sink transport in the Early Holocene and/or increased hillslope flux from Lesser Himalayan sources. [ABSTRACT FROM AUTHOR]

Understanding millennial‐scale fault activity and related structural architecture from seismic gaps in active orogens is important for assessment of future seismic risks. Here, we present new Late Pleistocene–Holocene shortening rates across a segment of the 600‐km‐long Medlicott‐Wadia Thrust (MWT) system in the Sub‐Himalaya (SH) from the far‐western Himalayan sector of Jammu. OSL‐dated offset and folded fluvial strath terraces provide a measure for the intra‐wedge convergence and document strain partitioning within the SH, among which the MWT is the most active. Estimated differential uplift rates across the frontal and rear splay of the MWT is 3.2 ± 0.8 mm/a and 3.1 ± 0.4 which translates into a cumulative Late Pleistocene–Holocene shortening rate of 5.5 ± 0.5–5.8 ± 0.5 mm/a on the MWT. Previously published balanced cross‐sections proposed deformation pattern and in range of ~1 mm/a. Our study reaffirms deformation rates from neighbouring MWT fault segments; moreover, it provides independent constraints to the structural architecture of the frontal fold‐and‐thrust belt and implies changes in fault displacement rates on Quaternary time‐scales. [ABSTRACT FROM AUTHOR]

The Lesser Himalaya exposed in the Kishtwar Window (KW) of the Kashmir Himalaya exhibits rapid rock uplift and exhumation (∼3 mm yr-1) at least since the late Miocene. However, it has remained unclear if it is still actively deforming. Here, we combine new field, morphometric and structural analyses with dating of geomorphic markers to discuss the spatial pattern of deformation across the window. We found two steep stream segments, one at the core and the other along the western margin of the KW, which strongly suggest ongoing differential uplift and may possibly be linked to either crustal ramps on the Main Himalayan Thrust (MHT) or active surface-breaking faults. High bedrock incision rates (>3 mm yr-1) on Holocene–Pleistocene timescales are deduced from dated strath terraces along the deeply incised Chenab River valley. In contrast, farther downstream on the hanging wall of the MCT, fluvial bedrock incision rates are lower (<0.8 mm yr-1) and are in the range of long-term exhumation rates. Bedrock incision rates largely correlate with previously published thermochronologic data. In summary, our study highlights a structural and tectonic control on landscape evolution over millennial timescales in the Himalaya. [ABSTRACT FROM AUTHOR]

Recovery of waste CO2 from flue gas involves two phase gas–liquid interactions for application in enhanced microalgal growth, CO2 bio-fixation and increased production of microalgal lipids for 4th generation biofuels. Mineralized CO2 as bicarbonate between pH 10 and 7 constitutes the major inorganic carbon for phototrophic microalgae. Consolidating Carbon Capture and Usage (CCU) technology with microalgal lipid synthesis, the present work exhibits design and optimization of a microbubble assisted CO2 sequestration reactor to recover CO2 from low concentration sources (5% v/v) and maximize microalgal lipid productivity without any nutrient stress. A venturi microbubble generator was amalgamated with a bubble column and the Reynolds number was used to define the hydrodynamic flow regime. At a steady volumetric liquid flow rate QL, corresponding to laminar flow conditions, the gas flow rate QG was varied in the range 0.1–1 L min−1 to determine the volumetric mass transfer coefficient KLa and the CO2 mass transfer efficiency. KLa and QG values were found to be linearly dependent in the QG range 0.1–0.7 L min−1, while CO2 capture efficiencies in the range 86% to 98% were obtained. The optimized medium recirculation sufficed for culture agitation and further aeration for mixing was not required. A correlation coefficient was derived, relating the change in gas–liquid interfacial area with the change in QG. The resultant system achieved a biomass yield of 0.454 g L−1 and a carbon content of 38.9% volatile suspended solids (VSS). Furthermore, a lipid accumulation of 35.9% on a dry cell weight basis and a lipid productivity of 11.64 mg L−1 d−1 exhibited feasible valorisation of sequestered carbon. [ABSTRACT FROM AUTHOR]

The interplay of tectonics, climate and erosion has been proposed as the driving factor behind the growth and evolution of the Himalaya. In this review paper, we focus on the neotectonic deformation history within the southernmost morphotectonic sector of the Himalaya (the Sub-Himalaya) through synthesis of geomorphic data. The Sub-Himalaya is arguably consuming ∼100% of the total Himalayan shortening since early Quaternary. We compiled geodetic shortening rates, paleoseismic events (historical earthquakes), shortening rates deduced from uplifted strath/fill terraces and shortening rates from balanced cross-sections from the north-western, central and eastern Himalayan compartments to obtain an orogen-wide perspective of Quaternary deformation. We supported the compiled data with topographic swath, longitudinal river-profile analysis and ks n plots of the existing drainage in those compartments. Review of the existing data shows a mismatch of the trend of the geodetic shortening rates with those of the millennial or longer timescales; however, Holocene and modern day-shortening rates are of same range (∼14–21 mm a−1). Quaternary shortening rates are much lower, probably due to a longer time-averaging. Except central Nepal, the other sectors show significant out-of-sequence thrusting (∼50% of the total) within the Sub-Himalaya since the Holocene. Paleoseismic data show variable recurrence intervals of large earthquakes along-strike (∼100–600 years) and large seismic gaps or slip-deficit sectors, which could potentially cause surface-rupture earthquakes in the future. [ABSTRACT FROM AUTHOR]

The southernmost thrust of the Himalayan orogenic wedge that separates the foreland from the orogen, the Main Frontal Thrust, is thought to accommodate most of the ongoing crustal shortening in the Sub-Himalaya. Steepened longitudinal river profile segments, terrace offsets, and back-tilted fluvial terraces within the Kangra reentrant of the NW Sub-Himalaya suggest Holocene activity of the Jwalamukhi Thrust (JMT) and other thrust faults that may be associated with strain partitioning along the toe of the Himalayan wedge. To assess the shortening accommodated by the JMT, we combine morphometric terrain analyses with in situ 10Be-based surface-exposure dating of the deformed terraces. Incision into upper Pleistocene sediments within the Kangra Basin created two late Pleistocene terrace levels (T1 and T2). Subsequent early Holocene aggradation shortly before ~10 ka was followed by episodic reincision, which created four cut-and-fill terrace levels, the oldest of which (T3) was formed at 10.1 ± 0.9 ka. A vertical offset of 44 ± 5 m of terrace T3 across the JMT indicates a shortening rate of 5.6 ± 0.8 to 7.5 ± 1.1 mm a−1 over the last ~10 ka. This result suggests that thrusting along the JMT accommodates 40-60% of the total Sub-Himalayan shortening in the Kangra reentrant over the Holocene. We speculate that this out-of-sequence shortening may have been triggered or at least enhanced by late Pleistocene and Holocene erosion of sediments from the Kangra Basin. [ABSTRACT FROM AUTHOR]

It has been proposed that at short timescales of 102–105 yr, climatic variability can explain variations in sediment flux, but in orogens with pronounced climatic gradients rate changes caused by the oscillating efficiency in rainfall, runoff, and/or sediment transport and deposition are still not well-constrained. To explore landscape responses under variable climatic forcing, we evaluate time windows of prevailing sediment aggradation and related paleo-erosion rates from the southern flanks of the Dhauladhar Range in the western Himalaya. We compare past and present 10Be-derived erosion rates of well-dated Late Pleistocene fluvial landforms and modern river sediments and reconstruct the sediment aggradation and incision history based on new luminescence data. Our results document significant variations in erosion rates ranging from 0.1 to 3.4 mm/yr over the Late Pleistocene. We find that, during times of weak monsoon intensity, the moderately steep areas (hillslope angles of 27 ± 13°) erode at lower rates of 0.1–0.4 mm/yr compared to steeper (>40°) crestal regions of the Dhauladhar Range that erode at 0.8−1.3 mm/yr. In contrast, during several millennia of stronger monsoon intensity, both the moderately steep and high slope areas record higher erosion rates (>1-3.4 mm/yr). Lithological clast-count analysis shows that this increase of erosion is focused in the moderately steep areas, where Lesser Himalayan rocks are exposed. Our data thus highlight the highly non-linear response of climatic forcing on landscape evolution and suggest complex depositional processes and sedimentary signals in downstream areas. • Paleo-erosion rates in the Himalaya are modulated by climate forcing. • Erosion rates are higher during episodes of strong monsoon. • Topographic response to climate change is non-linear. • Rapid erosion during short-lived strong monsoon phases result in valley aggradation. [ABSTRACT FROM AUTHOR]

Two end‐member kinematic models of crustal shortening across the Himalaya are still debated: one assumes localized thrusting along a single major thrust fault, the Main Himalayan Thrust (MHT) with non-uniform underplating due to duplexing, and the second one advocates for out‐of‐sequence thrusting in addition to thrusting along the MHT and under-plating. Furthermore, several studies argue that all crustal shorting during the Quaternary is accommodated within Sub-Himalayan fold and thrust belt. In this study, we combined tectonogeomorphic field observations, topographic analysis and luminescence dating of the Quaternary alluvium from the Kishtwar region in NW Himalaya. We have used 30m SRTM data to analyze the regional geomorphic parameters of the area and found that the river Chenab shows, as previously reported, significant changes in the longitudinal river profile, hypsometric integral, valley width and normalized steepness indices across the Kishtwar window situated ~ 150 km inside the Himalayan front. Unadjusted hypsometry, high ksn values, and several non-lithological knickpoint zones in the Chenab river profile hints towards possible ongoing neotectonic activity especially at the western margin of the window. We combined our morphometric analysis with field observation and field data on rock strength and observed tilted Quaternary deposits along the Chenab valley. We have observed faults disrupting Quaternary fluvial sequences and ~20֯ NE-tilted fluvial sequence of pebble conglomerate and coarse sand layers in the vicinity the town of Kishtwar. Even, the observed knickpoints within the window do not correspond to significant changes in the substrate rock strength and therefore hint about their non-lithologic origin. We also observed changes in the drainage pattern of Chenab, as it was frequented by large landslides (despite being located in a fairly-low rainfall region) and landslide-dammed lakes throughout the Kishtwar window and downstream. Previously published young (<3 Ma) apatite fission track ages from the Lesser Himalayan duplex in the Kishtwar Window suggest higher exhumation over million-year timescale. Therefore, our findings possibly hint towards a protracted tectonic uplift process – and the quaternary tilted deposits suggests that this deformation is active until today or very recent. Moreover, frequent low-magnitude mid-crustal (8-30 km) seismic events, steep channel gradients, high angle bedrock foliations of the Lesser Himalayan duplex, multiple knickpoints and young AFT ages within the Kishtwar window hints about active shortening accommodated due to movement along a mid-crustal ramp of the MHT.We are processing the OSL samples obtained from the deformed sand and silt layers within the alluvium. We are hopeful that we will be able to chronologically constrain the late Quaternary deformation with the new luminescence ages. [ABSTRACT FROM AUTHOR]