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Anisotropy of Magnetic Susceptibility (AMS) as a tool has been explored here to investigate the nature of petrofabrics in Deccan Volcanic Province (DVP) of west-central Indian region by representative sampling in typical pahoehoe and rubbly pahoehoe lava flows, dikes within flows, shear zone and the impact crater units. The rock magnetic analysis indicate varying degree of concentration of titanomagnetite compositions dominated by multi domain (MD) to pseudo single domain (PSD) grains favoring shape anisotropy of minerals that form primary fabrics. The pahoehoe type lava flows shows planar oblate fabrics without any preferred orientation of principal susceptibility axis (K1) depicting crystal settling (of magnetic grains) as chief mechanism of fabric development. The rubbly pahoehoe type lava flow exhibit prolate fabrics with well clustered maximum susceptibility axis within horizontal to sub-horizontal planes depicting their response to viscosity shear. The dykes show well clustered K1 parallel to it's plane locked during rapid contractional cooling. The sampling at Lonar impact crater was unable to trace any clear fabric due to impact/shock induced deformation and rather preserve the primary fabrics. Further, the shear zone depict random fabrics demanding more detailed and systematic sampling in both the cases. The present investigation infer that the magnetic mineralogy and magnetic fabric variations in the DVP are controlled by the flow mechanism and style of cooling that is characteristic of the given flow unit or dike and any secondary or superimposed fabric needs to be examined by critical sampling strategy. While more detailed attempts are required to establish the AMS as a tool to record various aspects including the flow dynamics and rate of effusion in the vast terrain of DVP; the present approach is useful to characterize and correlate the lava flow units and dyke occurrences. Copyright 2017 Geological Society of India

This paper deals with the characteristics and composition of municipal solid waste (MSW) generated in Sangamner city. The composition of solid waste was studied by segregating it into different component, i.e., kitchen waste, paper, earth and fine material, slaughter house waste, leaves, metals, etc. These components were categorised into organic waste and inorganic waste. It was observed that Sangamner city produces around 61% organic waste, and the rest is inorganic waste. The characteristics of organic solid waste, i.e., pH, electrical conductivity, moisture content, organic carbon, nitrogen, phosphorus and potassium were evaluated. The analysis of organic content of MSW indicates that it is good source of nutrients for the agriculture sector whereas inorganic material can be used for landfill.

Godavari Drainage Basin (GDB) represents the largest Peninsular source of sediment flux into the Bay of Bengal. Mineral magnetic measurements are carried out on the GDB sediments along with the surface sediment cores from the adjoining western Bay of Bengal to explore the relationship between the two. The sediments from Godavari river transact shows varied floodplain to bed load composition with the former dominated by unimodal soft ferrimagnetic, Deccan basalt source. Whereas, the bed load show polymodal composition of mixed nature dominated by silici-clastic sediments derived from the Precambrian granites and Proterozoic sequences. The surface sediment cores (∼100-300 cm) from the Bengal fan region off the Godavari delta broadly display an increasing trend in ferrimagnetic mineralogy towards top. Based on mineral magnetism the ferri- and para-magnetic susceptibilities are assigned to the basaltic and siliciclastic sources, respectively which also represents the low and high rain fall zones. The increasing upwards trend of the ferrimagnetic minerals in the western Bay of Bengal sediments, therefore, can be related to the predominance of basaltic source over the siliciclastic/cratonic source from the GDB. These controls of magnetic susceptibility in the Bengal fan sediments are assigned to the fluctuation of the two sources as a result of differential weathering in response to monsoonal variability. Copyright 2015 Geological Society of India

Wehrlite xenoliths recovered from lamprophyre dykes from Sarnu–Dandali alkaline igneous complex record three distinct events of modification in the mantle below northwest India. The first event marks mantle metasomatism by carbonate-rich fluids from the upwelling mantle, which formed secondary olivine and clinopyroxene at the expense of orthopyroxene, in mantle peridotite with little or no orthopyroxene. The phlogopite veining characterizes the second event in the mantle during rifting. These veins are formed by the crystallization of upwelling silica undersaturated alkaline fluids along the fractures and grain boundaries in the carbonated metasomatized mantle. Petrographic observations reveal separate phlogopite veins and carbonate infiltrations where carbonate activity preceded the phlogopite veining. The final event is an eruption of lamprophyres and mela-nephelinites in the study area at the later phase of the Deccan eruption, transporting wehrlite xenoliths to the surface. Estimated temperatures range from 911° to 940°C and pressure from 15.6 to 19.3 kbar with an average of 18.5 kbar, showing their derivation from a shallower depth of subcontinental lithospheric mantle (56–67 km). Separation of Greater-Seychelles from India at c. 68.5 Ma under extensional tectonic settings led to the lithosphere thinning and formation of wehrlite xenoliths in the rift margins.

Based on field documentation, we produce a comparative analysis of soft sediment deformation and other sedimentary signatures indicative of paleotsunami at two beach sites on the west coast of India. Trench profiles from these sites depict major differences in morphology of the structures as a result of greater overpressure from terrigenous backwash deposition at Dive Agar compared to Guhagarh, where the backwash flow escaped through an estuarine outlet. The occurrence of sporadic boulders, wedge-shaped heavy mineral sand layers and capping of the deposit by a pedogenic surface at Guhagarh depicts an older tsunami of larger magnitude compared to Dive Agar. The collective orientation of the characteristic signatures suggests two different sources of tsunami at Dive Agar (from Sunda arc in the SE) and Guhagarh (from Makran in the NW) that are further modeled to suggest the probable paleo-oceanographic conditions. The style of paleotsunami signatures are thus indicative of the coastal response to the arriving tsunami which is further controlled by the direction of source and the morphology of the coast. The study of paleotsunami records therefore provides useful information on the local coastal response to an arriving tsunami which is essential for vulnerability studies and better preparedness.

Mineral magnetic analysis including thermo-magnetic studies and clay mineralogy on bed load and floodplain sediments from the Godavari river indicate distinct mineral assemblages. The floodplain sediments up to the delta region are characterised by unimodal ferrimagnetic mineralogy marked by the presence of maghemite and single domain magnetites derived from Deccan basalts. On the other hand the bed loads show varied magnetic mineral assemblages depicting greater local mixing from the non-basaltic bedrock province. The temperature dependent magnetic susceptibility and clay mineralogy of the floodplain samples show titanomagnetites (Fe3O4-Fe2TiO4), maghemite (χLF-Fe2O3) and smectite that are characteristic of the Deccan Volcanic Province (DVP). Presence of this ferrimagnetically dominant unimodal assemblage up to the delta region and probably into the Bay of Bengal off the Godavari river is attributed to extensive chemical weathering of the basalt. The quantitative approach of mineral magnetism, therefore, can be used to study the paleomonsoon variability and its relation to Deccan basalt weathering from the Godavari-Bengal fan system. Copyright 2014 Geological Society of India

We present here lithofacies and mineral magnetic results from a ∼50 m thick composite record of fluvial, lacustrine and aeolian facies within the Leh valley basin of Indus River in Ladakh Himalaya. Mineral magnetic studies decipher interplay of two contrasting sediment sources viz., the unimodal ferrimagnetic source derived from Ladakh batholithic glacial domain and mixed ferri-to antiferromagnetic source derived from Indus sedimentary sequence. The lithofacies variability expresses dynamic changes in the depositional regimes controlled by base level fluctuations that are governed by the interaction of basin fill conditions and the response to Late Quaternary climatic perturbations. A three stage evolution of the Leh valley basin is proposed after comparison to other characteristic lithofacies changes within the valley as: (I) the basin under-fill conditions marked by fluvial and fluvio-lacustrine phase till ∼24m (∼64 Ka OSL age) above modern base level followed by (II) predominantly varved, glacio-lacustrine, basin overfill phase till 38m (∼28 Ka) gradually passing into an aeolian phase; and (III) basin incision that began at the earliest Holocene warming. Advancement and retreat of glaciers from the transverse valleys, attributed to climatic oscillations, appears to have greatly controlled the basin-fill conditions in the Leh valley. The present approach demonstrates its larger scope in recording the Late Quaternary response of individual valley basins to delineate local and regional attributes of climate change in the Himalayan and Karakoram region. Copyright 2013 Geological Society of India

The major water-soluble ions, organic carbon (OC), elemental carbon (EC) and mass concentration of fine- (PM2.5) and coarse-mode (PM10–2.5) aerosols were measured at Pune during January–December 2016. The mass closure approach was used by comparing the sum of the masses of the individual chemical species to the gravimetric PM obtained by weighting the filter samples. The 1 year mean total mass concentration of fine and coarse mode was 40 µgm−3 (64%) and 23 µg m−3 (36%), respectively. The PM2.5/PM10 ratio was 0.64 ± 0.9 indicating an abundance of fine-mode particles over Pune during the study period. A principal component analysis identified three components, where the one with highest explanatory power (59%) displayed clear impact of anthropogenic sources on the measured mass concentration of a majority of the compounds. The strong linear relationships between EC, OC, nss-SO42− and nss-K+ suggest a predominance of a common primary source, with a contribution from biofuel as well as biomass burning sources. Keeping the strong correlation and sources of individual chemical species as the base, it was noticed that (1) major contributors to fine- and coarse-mode particles over the Pune regions are carbonaceous aerosols and secondary inorganic aerosols (non-sea-salt SO42−, NO3−, and NH4+), (2) anthropogenic aerosols contribute mostly to the fine-mode, and (3) meteorological parameters play an important role in controlling levels of fine- and coarse-mode particles. Taken together, the study clearly indicates the dominance of anthropogenic sources during the entire year with more significance in the winter season.

We describe here a sequence of soft sediment deformation (SSD) structures at Dive Agar beach near Srivardhan in the west coast of India. The ~120-cm-thick sediment package is represented by a basal undeformed sand (layer A) sharply cut by ~30-cm-thick intermixed beach sand and terrigenous sand (layer B1) followed by complex load structures and convolutions (8–15 cm) within a coarse sandy layer (B2). The layer B2 is scoured by terrigenous sand (layer C1) which is capped with a silty mud layer (C2). The entire sequence (B2–C1–C2) is intruded by sand dykes originating from the lower layer B1. This sediment package is further overlain by a heavy mineral reach marine sand (layer D) with liquefactions long axes inclined southward as a result of forceful long-shore drift. The profile ends up with coarse-grained, poorly sorted sand including angular clasts of terrigenous outwash deposits indicating return of distal inundations. Intense deformation (liquefaction) is restricted to the heavy mineral-rich marine and the intermixed sands (layers B2 and D), whereas the terrigenous sand layers show scoured bases with oscillatory and pebbly tops. The presence of complex load structures injecting into the underlying layers, the top-truncated sand dykes, macro-thrust faults, scouring, and inclusion of coral fragments can explain it as a record of tsunami in the west coast. Occurrence of un-decayed consumer plastic material within the deformed layers suggests it as one of the most recent tsunami events (i.e., 2004 IOT), the only reported event after 1945 in the west coast. Alternative marine and terrigenous sands are characteristic of tsunami run-up and backwash deposits, while the dimensions of SSDs may be related to the <2 m magnitude (height) of the 2004 IOT at Dive Agar.

A field and imagery based study at the eastern margin of the Deccan Volcanic Province (DVP), and in the Precambrian terrain of Adilabad and Karimnagar districts of Andhra Pradesh, India display a striking response of the Godavari and Kaddam rivers to Kaddam lineament-fault fracture (KLF) system. Brittle to ductile deformations within the Precambrian formations indicate its antiquity, while the continuity of Kaddam lineament over DVP suggests its Tertiary reactivation. The morpho-tectonic response of the Godavari and Kaddam rivers in this area depict southward tilt of the fault block west of Kaddam fault during Quaternary. In the given set-up we postulate a greater role of crustal loading of the Deccan traps, and its rapid erosional unloading during Late Cenozoic intensified monsoon conditions as one of the causative factors for the above neotectonic response demanding further detailed work on the KLF and elsewhere in the peripheral regions of DVP encountered by active faults and old fractures. Copyright 2013 Geological Society of India