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This article presents the results of dynamic tests of sandstone samples differing in strength parameters and porosity, which were carried out with the use of the split Hopkinson pressure bar (SHPB). For this study, three types of sandstones were considered: two from the region of India (Kandla Grey and Apricot Pink) and one from Central Europe (Barwald). The strength parameters of the samples were identified in static tests (UCS, BTS tests), whereas the porosity was measured using computed tomography. The performed scanning allowed the volume of the pores and their distribution in the samples to be identified. Dynamic tests involved loading the cylindrical samples with a diameter of 23 m in the range of high strain rates, i.e., ε ˙   = 102 ÷ 103/s, using the SHPB (split Hopkinson pressure bar) method. Samples with three different values of slenderness were used for testing (L/D = 1, 0.75 and 0.5). Based on the dynamic characteristics of the samples, the maximum dynamic stresses, Dynamic Increase Factor (DIF) and the amount of energy absorbed by the samples were determined. The conducted research indicates a significant impact of material porosity on the amount of dissipated energy under conditions of high strain rates. The research indicates that the values of this parameter for Apricot Pink and Kandla Grey sandstones (slenderness L/D = ¾ and L/D = ½) are similar, although the uniaxial compressive strength (UCS) of Kandla Grey sandstone is approximately 60% higher than that of Apricot Pink sandstone. As a result of the sample destruction process, various forms of sample destruction were obtained. The performed grain analysis indicates a significant increase in the smallest fraction (<0.5 mm) in the case of the sandstone with the highest porosity (Apricot Pink—55% of mass outcome) in comparison to the sandstone with the lowest porosity (Kandla Grey—12% of mass outcome). [ABSTRACT FROM AUTHOR]

This experimental study aimed to investigate the potential control of microstructural-mineralogical characteristics on thermal properties and its relation with the deformational behaviour in mild to high temperature (25°–800°C) regime of coal-bearing sandstone from an underground coal mine fire region. Barakar sandstone from Jharia Coalfield, India, one of the world's largest underground coal mine fire regions, was chosen. The thermal parameters and their relations to the mineralogical, microstructural, and damage characteristics of Barakar sandstone have been discussed. Thermal conductivity (λ), thermal diffusivity (κ), and specific heat capacity (Cp) of heat-treated samples were determined using the transient plane source method. Additionally, detailed petrography, scanning electron microscopy, and electron probe micro-analyser were used to understand the thermal effect on mineralogy and microstructures. The deformational behaviour with elevated temperature was investigated through the universal testing machine. The obtained results suggest three characteristic temperature regimes: mild temperature regime (25°–300°C), transitional temperature regime (300º–500°C) and high temperature regime (500º–800°C). Moreover, prediction models for thermal properties have also been developed using multi-gene genetic programming (MGGP), considering physical properties as input parameters. In view of experimental constraints to determine the thermos-elastic properties of a rock due to tedious experimental processes, the proposed prediction models shall be very useful to indirectly estimate the thermal properties of sandstone rocks using easily determined physical parameters. The outcome of the present study may be useful to understand the subsidence induced by underground coalmine fire, which is a distressing issue in the Jharia region due to persistent coalmine fire. [ABSTRACT FROM AUTHOR]

In this study, we report well-preserved fossil remains of Nimbia from the Ediacaran Sonia Sandstone of Jodhpur Group, Marwar Supergroup in the Sursagar area of Jodhpur district, Rajasthan, western India. Here, two species of Nimbia, namely Nimbia occlusa and Nimbia dniesteri, have been recorded on medium- to fine-grained sandstone bedding surfaces. The N. occlusa forms are circular to ovate and elliptical imprints with a smooth and flat central part and enclosed by a single thick, annular marginal rim, whereas the N. dniesteri remains are circular to sub-circular discoid impressions with a trapezoidal structure. Here, the recorded N. occlusa is common compared to the N. dniesteri fossil forms in the Ediacaran Sonia Sandstone. These Nimbia fossil forms are found in the Sonia Sandstone in terrestrial to marginal marine habitats with moderate hydrodynamic forces. [ABSTRACT FROM AUTHOR]

The data on petrography and geochemical behaviour of Neoproterozoic siliciclastic sandstones of Kanpa-Tempa area from Chandrapur District are presented here to determine the provenance, source rock weathering and tectonic setting. The major elemental composition reveals that the Neoproterozoic sandstones are mainly as litharenite. The interrelationship of Zr vs. TiO2, Y/Ni vs. Cr/V, TiO2 vs. Al2O3, high LREE/HREE ratios (8.97 to 12.46) and negative Eu anomalies (Eu/Eu*= 0.52 to 0.79) suggest that the sandstones were mainly derived from the parent felsic igneous rocks. The higher values of paleo-weathering indices such as Plagioclase Index of Alteration (PIA), grading from 66.42 to 80.82 and Chemical Index of Weathering (CIW), ranging from 70.58 to 82.39 clearly point out that the sediments and their source rocks experienced moderate to intense weathering. The Chemical Index of Alteration (CIA) values (ranging from 62.79 to 76.16) coupled with average content of K2O (1.66) is indicative of K-addition during diagenetic processes. Similarly lower values of K2O/Na2O ratio (0.52) suggest limited chemical maturity and SiO2-K2O/Na2O discrimination plot exhibits the active continental marginal tectonic settings. [ABSTRACT FROM AUTHOR]

For decades, naming the rosetted trace fossil species of Dactyloidites ottoi or Haentzschelinia ottoi has been a matter of discussion. The phobotactic behaviour of the trace makers reflecting systematic mining to form branched radial elements converging at the central vertical shafts in both the ichnogenera are similar and foreknown. Berriasian marine deltaic deposits of the Jhuran Formation, India, contain several such endichnial mid-tier traces of Dactyloidites ottoi (Geinitz, 1849), at six different levels in a highly bioturbated subarkosic bedded sandstone. Its occurrence is associated with Arenicolites, Ophiomorpha, Planolites and Rhizocorallium. The analysis of the trace fossils from the archives reveals the mining strategy resulting in Cambrian to Holocene Dactyloidites and Haentzschelinia traces. The present specimens of D. ottoi and the morphological variants within the traces also indicate an effect of the variations in palaeobiological and palaeoenvironmental aspects. [ABSTRACT FROM AUTHOR]

We consider existing reliable data indicate the depositional age of the uppermost sandstone (Maihar Sandstone) of the Vindhyan Supergroup to be closer to 1000 Ma. We consider the penultimate statement by Pandey et al. (2023) "... the Maihar Sandstone is deposited within the Ediacaran Period" (our italics) is erroneous. In this note, we address both the dubious geochronology and the dubious biostratigraphy called on by Pandey et al. (op. cit.), and comment on the impropriety of changing extant stratigraphy on the basis of either. [ABSTRACT FROM AUTHOR]

Spectacularly preserved yet least studied middle to late Eocene Kopili Formation in parts of East Jaintia Hills district, Meghalaya has been documented to understand the provenance, tectonic setting and palaeoweathering employing petrological and geochemical attributes. The Kopili Formation is characterized by alternations of fossiliferous marl-splintery grey to black shale-siltstone and fine to medium grained ferruginous sandstone with occasional coal streaks. Petrographically, Kopili sandstone has been grouped into two categories i.e. subarkose and sublitharenite. Geochemically, Kopili sandstone possesses high SiO2 and relatively low Al2O3 and Fe2O3 confirming to the modal composition Q72.70 F6.57 RF7.01 CT3.12 Mx2.28 M2.07 HM1.82. These are quartz-rich (SiO2 75.96%) clean sandstone depicting strong negative correlation of SiO2 with rest of the major oxide except for CaO which is relatively weak. High SiO2 is in conformity with quartz enrichment (73.50%), does indicate a passive (atlantic type) continental margin set up for the deposition of Kopili Formation. Neo-development of quartz and feldspar in parts reflect high degree of diagenesis. Chemical indices like CIA, CIW, PIA and ICV reveal intense weathering under semi-arid to semi-humid climatic conditions. Besides minor contributions from continent interior, sediments were largely derived from recycled orogen involving rhyolitic / granitic sources containing plagioclase feldspars in the range of An0-An70 as evident from geochemical attributes. [ABSTRACT FROM AUTHOR]

Miocene Tipam Sandstone Formation in parts of Cachar Fold Belt, Northeast India has been studied using petrographic and geochemical attributes to investigate the composition, paleoweathering, tectonic setting, and source rock characteristics. It comprises of coarse to medium grained false-bedded multistoried ferruginous sandstone and variegated sandy clay. Petrographically, these sandstones belong to sub-lithic and lithic arenite varieties possessing an average recalculated modal composition of Q67F13R20. Geochemically, Tipam sandstones have high SiO2, more Na2O than K2O, and relatively low Fe2O3, MgO, MnO content in accordance with the modal composition. Weathering indices like CIA, CIW, PIA and ICV suggest derivation of sediments from low to moderately weathered source terrain bearing plagioclase feldspar in the range of An10–An55 comparable to granodiorite and granite composition. Dominantly a passive margin setup with high degree of sediment recycling has been envisaged during the deposition of Tipam Sandstone Formation. [ABSTRACT FROM AUTHOR]

The present study records the triangular-shaped Ediacaran fossil identified as Thectardis avalonensis from the Sonia Sandstone of Jodhpur Group, Marwar Supergroup, western India. These Ediacaran fossil specimens are preserved in convex (positive) relief, but one is in negative relief on the bedding planes of sandstone in the Sursagar mines area. T. avalonensis is well-preserved, unskeletonized, elongated and triangular in shape, with sharp, raised marginal rims or ridges that widen at the triangular base and taper towards the apex of the organism. This Ediacaran triangular-shaped T. avalonensis organism is recorded for the first time from India. The phylogenetic affinity of T. avalonensis is still uncertain, as some have interpreted it as a sponge based on a body plan consistent with the hydrodynamics of the sponge water-canal system, which lacked a mouth or movement and its length-width ratio of more than 1.6. As well as these, T. avalonensis may also belong to Diskagma-like lichen or living Cladonia-like lichen group and the Auroralumina-like cnidarian organisms of the Ediacaran crown group. [ABSTRACT FROM AUTHOR]

The heavy mineral assemblage (HMA) of sandstones belonging to Mesoproterozoic Kaimur Group in the eastern Son valley, Central India, was investigated. The present communication is aimed at assessing mineralogical maturity, quantifying the contribution of heavy fraction to the bulk rock and its REE budget, sediment recycling and provenance. The transparent heavies record a relative decreasing trend upwards from 63 to 36.4% and on the contrary, opaque heavies show gradual increasing trend upwards from 36.4 to 65.4%. Tourmaline in the transparent heavy fraction reveals an overall decreasing trend of 59–22.8%. Whereas, zircon registers an increasing trend of 3.3–9.5% stratigraphically upwards. The contribution of opaque detrital clasts of ferruginous material composed of hematite and magnetite increases in the Upper Kaimur Sandstone. Tourmaline and zircon grains are characterised by etched, pitted and grooved surfaces. Zircon is also present as tiny inclusion within tourmaline and zircon itself. Heavy fraction of Upper Kaimur sandstone from the lower stratigraphic horizon exhibit lower ∑REE as compared to higher levels. The heavy fraction exhibit LREE/HREE < 1 as compared to bulk rock which has 8–10 times higher ratio. Heavy fraction exhibits enrichment in HREE and [Gd/Yb]N = 0.36–0.43, stratigraphically upwards, which is consistent with increasing Zr values suggesting zircon to be the major contributor to the REE budget of Upper Kaimur Sandstones. The percentage contribution of the zircon to the REE budget of bulk rock could have been ~50–60%. ZTR index (99–100) reveals mineralogically mature nature of Kaimur sandstones. Dominance of zircon amongst the heavies and Th/Sc vs. Zr/Sc plot shows the effect of zircon addition and sediment recycling. The plausible explanation for dominance of opaque minerals in HMA in the Upper Kaimur reflects their contribution from Paleoproterozoic metasedimentary rocks of Mahakoshal Group. HMA of Kaimur sandstones suggests derivation from granitic source. Nb/Yb vs. U/Yb diagram indicates that zircon was derived from magmatic arc source, which is in conformity with inference that Bundelkhand Granite Complex and Chhotanagpur Granite complex dominantly contributed to the Lower and Upper Kaimur Groups, respectively. Research highlights: The paper deals with the study of heavy mineral assemblage of the Kaimur Group sandstones, Vindhyan Supergroup, Son Valley, Central India. Provenance, sorting and recycling of the sediments were inferred. The ferruginous clasts found in the Dhandraul Quartzite/Sandstone also have been studied to understand their mineralogy and texture. Tourmaline and zircon dominate the Lower and Upper Kaimur Sandstones, respectively. The provenance of the Lower Kaimur sandstones is Bundelkhand granite, and Upper Kaimur sandstone is Chhotanagpur Gneissic Complex. The dominance of zircon in HMA and Th/Sc vs. Zr/Sc plot shows the significant effect of zircon addition and sediment recycling. The occurrence of ferruginous detrital clasts in Upper Kaimur sandstones can be attributed to increasing detrital input from adjoining Mahakoshal Group that has the presence of BIFs/BHQ/BHJ in the Agori Formation. The heavy fractions from sandstones of Mangesar Formation and Dhandraul Quartzite from different horizons exhibit an increase in Zr and HREE stratigraphically upwards. This suggests remarkable enrichment of HREE, low LREE/HREE, [La/Yb]N <1 and [Gd/Yb]N <1. HREE enrichment is proportional to the Zr concentration signifying the dominant role of zircon amongst the heavies in managing the ΣREE budget of the bulk rock. The percentage contribution of the zircon is calculated to be ~50–60%. [ABSTRACT FROM AUTHOR]

Here we describe the Tribrachidium and Albumares Ediacaran organisms belonging to phylum Trilobozoa in the Sonia Sandstone of Marwar Supergroup, western India. Between the two Ediacaran genera, Albumares brunsae was the first to be discovered in India, while Tribrachidium heraldicum was the first record from the Marwar Supergroup. T. heraldicum is soft-bodied, discoidal or disc-shaped (in plane view) and slightly conical-shaped (when found with up to 2 mm vertical relief) with three elevated lobes (arms) or ridges bounded by a well-defined peripheral ring. A. brunsae is soft-bodied, flattened, low-relief, circular to sub-circular and with a tri-lobed (three elevated arms/rays) shield having branching rays that radiate outward from the centre to the outer edge of the peripheral ring. Both Ediacaran taxa occur here as convex or positive reliefs with triradial symmetry on medium to fine-grained sandstone bedding planes in the Sursagar area and show the Flinders Ranges style of preservation. [ABSTRACT FROM AUTHOR]

Geochemistry and petrography of the late Cretaceous Pab sandstone exposed at the Laki Range, Southern Indus basin has been carried out in order to acquire better understanding of source rock, paleoclimate and the tectonics. The unit in the study area dominantly comprises of sandstone with some conglomeratic sandstone and mudstone beds. The petrographic studies of Pab sandstone reveal the quartz as the major mineral constituent in almost all analyzed samples. The monocrystalline variety of quartz was seen dominant than the polycrystalline; with dominant non-undulatory extinction, the undulation was also noticed. In addition, studied samples reflect medium to coarse size grains, angular to subangular to subrounded shape characterized with the grain to grain contacts as point to straight and sutured. Iron oxide is observed to be leading cement with calcareous as the second most abundant cementing material, the matrix was also observed in minor amount. The monocrystalline quartz abundance in Pab sandstone indicate the existence of granitic rocks in the source region. The lesser fragments of feldspar and lithics suggest of their alteration to various clay minerals. The Pab sandstone is composed mainly of monocrystalline quartz derived dominantly from craton interior as revealed through plots of model composition on Quartz -Feldspar-Lithics (QFL) and Quartz Monocrystalline-Feldspar-Lithics (QmFLt) plots as per the petrographic characterization. The major element geochemistry of Pab sandstone indicates that the samples comprised of abundant SiO2 (56.21 to 69.93 wt.%), Al2O3 (12.56 to 22.98 wt.%), CaO (1.68 to 6.38 wt.%) and Fe2O3 (3.87 to 14.12 wt.%), the rest of the major oxides are <2 wt.%. Additionally, major element compositions suggest the sediment derivation from a granitic source. The Chemical Index of Alteration (CIA) values ranging from 61.12 to 83.75 and the values of Plagioclase Index of Alteration (PIA) ranging from 59.94 to 89.44 suggests that studied sediments underwent the weathering conditions being moderate to intense in warm and humid climate regime. The present petrographic findings and geochemical data suggest the sediment derivation from huge Cratonic landmass (Indian Shield). The similar rock types in the form of Nagar Parkar Igneous Complex are still exposed in the southeast of study area in Pakistan and Malani Igneous Suite in India. [ABSTRACT FROM AUTHOR]

The study considers the impact of the degree of weathered material constituting the sedimentary rocks on the strength of the Lower Gondwana coal measure rocks. The dependence of the strength of primary rocks on the alteration indices has been previously studied, but it is unknown for secondary/sedimentary rocks. Therefore, in this paper, Lower Gondwana coal measure rocks (sandstone and shale) from the most productive coalfields of India, the Barakar and Raniganj coalfields, have been studied geochemically and geomechanically to find out their correlation. Geochemically, the study revealed that an arid, non-marine, and deltaic depositional environment prevailed during the sedimentation of Barakar and Raniganj Formations. The provenance was deduced to be mafic igneous. It was also deduced that the Lower Gondwana sandstone is clay-rich, and the sandstone samples fall in the shale field in the chemical classification scheme for terrigenous clastic sediments. The weathering indices, along with the uniaxial compressive strength (UCS) of the Barakar and Raniganj Formation coal measure rocks, have been assessed. The dependence of UCS on the weathering indices has been evaluated, and positive relationships were obtained. [ABSTRACT FROM AUTHOR]

Present study of vanadium mineralization in the Sonia sandstone of Jodhpur Group shows first hydrothermal activity in the Sonia sandstone of Marwar Supergroup. The Sonia sandstone served as a host for the mineralizing solutions. The vanadium mineralization occurred in sandstone- gritty sandstone-conglomerate along faults. Field relationship and petrological study suggests that mineralization is filled by epithermal solutions and provide a better understanding of the timing and nature of the alteration processes. Though the source of the vanadium is not well constrained, but is possibly from the partial melting of banded gneissic complex-II (Sirohi Group), the source (crustal) melt had assimilated material from the rocks of Sirohi Group in significant amount. Deposition of tuffs at top of Sonia Formation (Chhoti Khatu) and emplacement of last stage Malani dykes suggest that the last phase of Malani magmatism generated heat for the partial melting of banded gneissic complex-II (Sirohi Group). The occurrence of vanadium in sandstone—gritty sandstone—conglomerate from Sonia Formation of Marwar Supergroup has opened a new chapter to explore uranium which generally occurs after vanadium mineralization in conglomeratic sedimentation. [ABSTRACT FROM AUTHOR]

Cementation factor has a crucial role in evaluating volumetric reserves for heterogeneous clastic reservoir. Bioturbation is a prominent source of heterogeneity existing in hydrocarbon-bearing formation across the world. The effect of bioturbation on the petrophysical properties of the clastic has not been comprehensively understood yet, especially its effect on cementation factor estimation. The precise description of such properties is beneficial in developing better volumetric estimates and optimizing field development planning. The present work discusses an approach to characterize cementation factor in bioturbated clastic Bhuj Formation, Kachchh Basin, India. In order to ascertain the cementation exponent for bioturbated media, an improved triple-porosity model is proposed by quantifying the total porous volume into three components, namely matrix 1, matrix 2 and bioturbated region. An equivalent resistance model is then developed by identifying the series and parallel relation between the two matrix components and the burrow. The experimental observations of electrical response indicated large variation in resistivity in vertical cores compared to horizontal cores. The decreased resistivity is due to the vertically aligned burrow which due to their enhanced porosity provides less tortuous path for current to flow. The triple-porosity model is validated with different porosity value of matrix 1, matrix 2 and burrow, and a cementation factor of 2.8 for higher bioturbated samples and 3 for lower bioturbated samples is obtained. This validates the previous understanding of enhanced flow and storage property and thereby produces a consistent way to evaluate total cementation factor. The correct estimation of cementation factor helps in precise evaluation of water saturation in bioturbated reservoirs. [ABSTRACT FROM AUTHOR]

Background: The mining industry has many hazards to which workers are exposed. Despite that, study on health hazards among mine workers are limited in India. Also, there are negligible studies on ex-miners in India. Thus, the present study tried to explore the current levels of self-reported morbidity among mine workers and ex-mine workers in the Karauli district of Rajasthan, India. Methods: This study was a comparative cross-sectional study conducted in the Karauli district of Rajasthan, India. A total of 218 mine workers, 137 ex-mine workers, and 203 non-mine workers were interviewed. An interview-led questionnaire recording the presence of self-reported health problems and demographic information was administered. Self-reported symptoms were classified according to the categories defined in the operational definitions. Results: Ex-mine workers moved away from mining due to respiratory problems (31%), weakness (24%), and TB (20%). Mine workers and ex-miners have significantly increased prevalence of respiratory-related symptoms and injury at the workplace, vision, and oral health problems than the non-mine workers. The adjusted odds of morbidity conditions such as cough up with blood, shortness of breath, and wheezing were significantly higher among ex-miners than current miners. Conclusion: This study identified respiratory symptoms, injury, vision loss, hearing loss, and poor oral health for both mine and ex-mine workers. The higher self-reported health problems for symptoms like cough up with blood, shortness of breath, and wheezing were found among ex-miners than current mine workers. [ABSTRACT FROM AUTHOR]

The approximately 2 km thick fluvio-lacustrine deposits of Pranhita-Godavari Gondwana syn-rift basin, ranging in age from 235 to 196 Ma, track the compositional changes from the Middle Triassic to Early Jurassic. Mineralogical and geochemical investigations, as well as paleocurrent data of the siliciclastic deposits of the four conformable formations—Yerrapalli, Bhimaram, Maleri and Dharmaram—trace the source of sediments to the south and southwest of the Gondwana basin. The dominance of arkosic to sub-arkosic sandstones in all the formations suggests mostly felsic sources. The high value of Zr/Sc, as well a high content of Hf, reflects the addition of zircon by sediment recycling. The index of compositional variability (ICV) and chemical index of alteration (CIA) values of these Gondwana samples suggest intermediate weathering of Proterozoic shales, granites and gneisses. The concentration of Cr and Ni, ratios of Eu/Eu* and (GdN/YbN) suggest a dominant post-Archean source. The insignificant variation in ICV and CIA values across the studied Mesozoic formations corroborates the continuation of syn-rift tectonics of the Pranhita-Godavari Gondwana basin since the Late Paleozoic. Sandstone samples show a gradual shift from arkose to subarkose in Yerrapalli, Barakar and Maleri formations, and to sublithic arenite sandstones in the younger Dharmaram formation, indicating recycling. However, the insignificant variation of feldspar and/or quartz content throughout these Mesozoic formations suggests lesser tectonic activity. The paleocurrent direction, shifting from NNW to NE direction, suggests a change in basin tectonism and/or sediment supply, which is corroborated by mineralogical and geochemical data. [ABSTRACT FROM AUTHOR]

Detrital mineralogy, major oxides, trace, and rare earth elements (REE) were examined in the Middle Jurassic Fort Member Sandstone (FMS) of the Jaisalmer Formation in Western India to understand palaeoweathering, provenance of sediments, and to decipher the tectonic setting. The sandstones are classified as arkose to sub‐litharenite types according to their relative percentages of quartz, feldspar, and lithic fragments, and major elemental ratios. The values of Chemical Index of Alteration (67–85), Plagioclase Index of Alteration (78–97) and Chemical Index of Weathering (83–97) along with A‐CN‐K diagram suggest moderate to intense chemical weathering in the source region. Presence of fresh feldspars and dominance of monocrystalline quartz, showing both parallel and undulose extinction, indicate plutonic and volcanic felsic igneous provenance. Contribution from metamorphic orogen sources is indicated by the lithic fragment population. Various geochemical parameters such as Th/Sc, Cr/Th, Ti/Zr, and Eu/Eu* support a dominant felsic provenance. Higher Zr/Sc ratios relative to the magmatic Zr/Sc‐Th/Sc trend, higher Zr and Hf concentrations in the FMS indicate some extent of sedimentary recycling and zircon sorting. LREE enrichment, flat HREE pattern, negative Eu anomaly and trace element ratios, in conjunction with palaeocurrent data, indicate a likely sediment contribution from basement source terrains including Erinpura‐Mount Abu‐Sirohi granites, Malani Igneous Suite, and Aravalli‐Delhi orogens. The major and trace element tectonic setting discrimination diagrams for the FMS indicate a passive margin setting. [ABSTRACT FROM AUTHOR]

The Kopili Formation of North Cachar Hills, NE India has been studied to unravel its depositional mode and provenance. For this, a study of grain size distribution and heavy mineral assemblage of representative sandstone samples of the Kopili Formation was undertaken. Further, the published information on the Kopili Formation occurring in the adjacent areas was compiled. The Grain size study reveals that the Kopili sandstones are mostly bimodal and polymodal, fine-grained sands mixed with medium grained sands, moderately well sorted to poorly sorted, coarse skewed to near-symmetrical, and platykurtic to extremely leptokurtic. The Passega CM (C= one percentile and M= Median) pattern discloses saltation and suspension as the dominant transporting modes of the studied sandstones. Linear discriminant function (LDF) analysis reveals that the Kopili sandstones were deposited in beach and agitated shallow marine environment. The heavy mineral assemblage represented by zircon, tourmaline, rutile, garnet, chlorite clinopyroxene, staurolite, and opaque indicates mixed provenance (silicic igneous and metamorphic) for the Kopili sandstones. The zircon-tourmaline-rutile (ZTR) maturity index ranging from 31.03 to 88.41 (average 64.49%) discloses immature to sub-mature nature of the Kopili sandstones. Based on the study it is inferred that the Kopili sediments are of mixed provenance and deposited broadly in marine environment. [ABSTRACT FROM AUTHOR]

Potential field methods are use to map the substructural features such as faults, fractures, shear zones and altered zones in the part of Vindhyan fringe belt of northern, MP. Geologically, the study area is represented by Vindhyan Supergroup of Meso to Neoproterozoic age. The area is mainly covered by alluvium which is characterized by river gravels, sand and residual soil. Bouguer gravity anomaly contour map brought out a broad gravity variation 'high' in southern part due to upliftment of basement rocks/ presence of denser rock below the Vindhyan formation, whereas gravity 'low' in northern part due to presence of low depression zone (altered/ weathered Sandstone and Limestone). The high dominant anomaly is observed in the southern and northern parts which may be due to effect of basement/ basic dyke of BGC and the presence of Ferruginous Shale and Ferruginous Sandstone, respectively. The 'high' residual gravity anomaly aligned approximately NW-SE is recorded and interpreted as inferred lineament on Bouguer gravity anomaly map in central part of the map which is reflected from shallow feature and not observed on geological map. The residual magnetic map shows clear increase of the numbers of the local magnetic anomalies with different polarities along with various shapes, extensions and orientations. The inferred as lineament in central part are clearly reflected in THDR and TDR map of gravity data, while the THDR of the magnetic data is not represented properly. The map of the TDR of the magnetic data depicts close to zero magnetic values that coincide with edges or boundaries of inferred lineament in central part of the map. The majority of solutions are falling varying depth from 0.5 to 2.5 Km. The solution of gravity data is falling at inferred lineament and contact between two litho-units varying depth from 0.5 to 2.5 Km in central part of the map. [ABSTRACT FROM AUTHOR]

Based on integration of field, petrographic and heavy mineral chemical data, this study highlights the source and tectonic setting of the Mesozoic sandstones of Kutch, Saurashtra, Narmada and Cambay basins at the western margin of India, formed by the progressive splitting of the eastern Gondwanaland. The Kutch Basin is dominated by arkosic sandstone, whereas Saurashtra, Narmada and Cambay basins show the predominance of sub-arkose and sub-litharenite. The modal analyses of framework grains in Kutch sandstones indicate basement uplift and transitional continent settings. In contrast, the sandstones of Saurashtra, Narmada and Cambay basins bear imprints of recycled orogenic and craton interior belts. The presence of abraded and detrital quartz overgrowth and rounded zircons in most sandstones reveal the recycling of sediments in these basins. Tourmaline and rutile mineral compositions constrain the possible lithology of source rocks. The tourmaline mineral chemistry (Ca-Fe tot -Mg plot) suggests the derivation of sediments from various sources, including Li-poor granitoids associated with pegmatites, aplites, Ca-poor metapelites, metapsammites and quartz-tourmaline-rich granitic rocks. The compositions of rutile grains (Cr vs. Nb plot) in sandstones indicate metapelitic sources. The gamut of all mineral chemical data supports the predominance of sediment sources from quartzo-feldspathic rocks with minor inputs from mafic rocks. Based on available paleocurrent data and correlation of source compositions, we infer that the Mesozoic sediments of Kutch, Saurashtra, Narmada and Cambay basins were primarily sourced by various lithologies of the Aravalli Craton. The Narmada Basin possibly received additional sediment input from the Bundelkhand Craton. [ABSTRACT FROM AUTHOR]

The coastal deposits along the eastern part of the Indian Peninsula are known for the high abundance of heavy minerals. The present study, as discussed here, has been undertaken along the south-western coastal part of Odisha, India, adjoining the charnockite–migmatite zone of the Eastern Ghat Mobile Belt (EGMB). The composition of the placers along the study area is primarily controlled by the detritus from the proximal hinterland rock type(s). The weathering index has been established based on the grain morphology, major element concentration and radioelement ratios. Petrological characteristics and grain morphology of monazite, zircon, ilmenite and rutile have been presented respectively, and their implications are discussed. The provenance study of these coastal placers is based on the abundance of rare earth elements (REE) and radioactive elements in the placer sands and the rock types in the study area. The tectonic implications are based on the major element abundance of the beach sands. [ABSTRACT FROM AUTHOR]

This study focuses on the descriptions of well preserved numerous Lockeia traces of bivalves from the Early Jurassic to Bajocian Thaiat Member of Lathi Formation, Jaisalmer Basin, Western Rajasthan, India. Here, both ichnospecies Lockeia siliquaria and Lockeia cunctator have been recorded from the yellowish brown fine grained rippled calcareous silty sandstone in Thaiat Section. The L. siliquaria trace fossils are small, elongated almond-shaped and oval-shaped oblong body structures with smooth surfaces, occurring as positive hyporelief and more or less tapering at both ends. The L. cunctator trace fossils are small, almondshaped oblong bodies with smooth surface structures, occurring as positive hyporelief with linear and clubshaped arrangement. The ichnotaxon L. siliquaria represents those places where the bivalve stopped temporally for feeding, whereas the L. cunctator are interpreted as locomotion traces with a resting or probing component of bivalves. Based on Lockeia trace fossil assemblages with associated fauna and trace fossils, we suggest shallow-marine environment for the upper part of the Thaiat Member of Lathi Formation. [ABSTRACT FROM AUTHOR]

Dried sandstone slurry (DSS) is generated during mining and processing of stone and is accounted as man-made hazardous waste material, contaminating the environment in nearby areas. The use of DSS in self-compacting concrete (SCC) was studied by partially substituting pozzolana Portland cement at different percentages. This represents the recycling element of the 3 R's of the environment (reduce, reuse and recycle). Mechanical and permeability properties were evaluated and the microstructure of SCC analysed with respect to a control mixture which is without sandstone slurry. Mechanical and permeability parameters were found to relate each other. With increased replacement of DSS, the porosity and hence the sorptivity coefficient of SCC also increased and its compressive strength decreased. The higher porosity caused a significant increment in the depth of carbonation. Scanning electron microscope (SEM) and X-ray diffraction (XRD) showed decreased calcium-silicate-hydrate (C–S–H) gel formation as the replacement percentage of DSS increased. This, along with the increased porosity and permeability, degraded the mechanical properties of SCC. The rapidly developing construction sector in India must meet the following indispensable criteria: low environmental impact at improved structural performance, economy and speed of construction. Utilization of sandstone waste is highly recommended from the above viewpoint. [ABSTRACT FROM AUTHOR]

The present study reports and discusses discoidal Ediacaran body fossils identified as Hiemalora stellaris from the Sonia Sandstone of Jodhpur Group, Marwar Supergroup, Western Rajasthan, India. These are preserved as positive relief on the yellowish-brown to pinkish-brown medium to fine-grained sandstone bedding surfaces in Sursagar area. Morphologically, these are circular to sub-circular, mostly flat-discoidal forms or discs surrounded by numerous radiating arms or appendages resembling tentacles. Hiemalora is reinterpreted and reconstructed as discoidal hold fast of benthic organism but not found the attached fronds or stem-like structures of the hold fasts in the present materials. The systematic palaeontology, palaeobiology, palaeoenvironment and age of the Hiemalora bearing Ediacaran Sonia Sandstone have been also discussed. [ABSTRACT FROM AUTHOR]

Coralline algae of the Late Pleistocene Miliolite Formation of Kachchh region, Gujarat, western India are studied in terms of taxonomy and their paleoenvironmental implications. The Quaternary bio-clastic sediments belonging to the Late Pleistocene Miliolite Formation are well exposed in Kachchh, western India and these sediments consist of sandy limestones and calcareous sandstones. The present paper deals with the study of coralline algae from the sediments of the Late Pleistocene Miliolite Formation. Twenty two species of coralline algae are being recorded for the first time from these sediments. Out of twenty two species, eight belong to non-geniculate coralline algae and fourteen belong to geniculate coralline algae. The geniculate coralline algal species are: Lithophyllum incrustans Philippi, Lithophyllum sp.1, Lithopyllum sp.2, Lithoporella melobesioides Foslie, Lithothamnion sp.1, Lithothamnion sp.2, Lithothamnion sp.3 and Lithothamnion sp.4 and geniculate coralline algal species are: Amphiroa anchiverricosa Johnson and Ferris, A. fortis Johnson, A. rigida Lamouroux; Arthrocardia cretacica Raineri, A. indica Kundal and Humane, A. konitaensis Ishijima; Calliarthron antiquum Johnson; Corallina grandis Rao, C. prisca Johnson, C. typica Ishijima; Jania guamensis Johnson, J. mengaudi Lemoine, J. sripadaraoi Kundal and Humane; J. vetus Johnson. The present coralline algal assemblage suggests that the sediments containing algae from the Miliolite Formation were deposited in the shallow water marine/beach environment. [ABSTRACT FROM AUTHOR]

Soft-sediment deformation structures play an important role in interpreting regional tectonics and basin evolution during slumping events. The Satpura Basin is interpreted as pull-apart with a monoclinal northerly palaeoslope throughout its evolution. The basin formed as a result of sinistral strike-slip faulting, induced by the ENE–WSW-trending Son-Narmada South fault in the north and the Tapti North fault in the south. We have analysed the slump folds within the basalmost Talchir Formation and related these to regional tectonics and palaeoslope changes in the Satpura Basin. The glaciofluvial strata of the Talchir Formation, exposed in the southern part of the Satpura Basin, record intricacies of folds created during slumping. Several fold styles can be distinguished, within alternations of competent sandstone and incompetent shale layers, some of which indicate buckling. Upright folds, resulting from pure shear, underwent rotation of their axial planes and fold axes during simple shear-dominated progressive deformation when the slump moved downslope. The soft-sediment deformation structures that we have studied show refolding patterns that closely resemble comparable folds known from lithified rocks. These layers with refolded structures are overlain by unde-formed sediments, which proves that they are the product of a single ongoing slumping process, rather than of successive deformation events. Our analysis of their fold axes and axial planes, together with fold vergences and thrust directions within the slumps, suggests a mean slumping direction towards the southwest. Analyses of slump folds and their relationship with regional tectonics have allowed us to reinterpret basin evolution history. The southwesterly trending palaeoslope of the basin suggest that the slope of the basin was not uniform throughout its evolution. At the opening, the oblique slip fault, which trended NE–SW, generated due to movement along the ENE–WSW basin bounding faults, was more active and triggered slumping event within the Talchir deposits in the basin. With progressive overlapping of the basin-bounding faults, the Satpura Basin gradually tilted towards the north. [ABSTRACT FROM AUTHOR]

The tectonic nature of Early Palaeozoic Kwangsian orogeny in the South China Block (SCB) is still debated, due to controversy whether there was a Cambrian ocean between the Yangtze Block and the Cathaysia Block. Similarly, continental affinities of the SCB with India and Australia in East Gondwana during the Cambrian are also controversial. Herein, we present detrital zircon U-Pb geochronology of Cambrian sandstone samples from the southern SCB. Cambrian samples (including our new samples and published samples) from the Cathaysia Block and the Yangtze Block show similar detrital zircon age spectra with one prominent age cluster of ~1000-900 Ma and several subordinate age groups, as well as similar cumulative proportion curves (CPC). Such signatures, together with other geological records, suggest that a Cambrian ocean did not exist between the Cathaysia Block and the Yangtze Block, and that Early Palaeozoic Kwangsian orogeny resulted from an intra-continental collision. Cambrian samples from the SCB have much more similar detrital zircon age spectra and CPC to those from Himalaya and Qiangtang than those from Australia, but detrital zircons in Cambrian samples from the SCB, Himalaya, Qiangtang and Australia have a similar prominent age group of ~1000-900 Ma. Thus, the SCB were likely located between Australia and India during the Cambrian, receiving sediments both from India and Australia. [ABSTRACT FROM AUTHOR]

Mechanically strong sandstones consider as a potential construction material which can withstand modest load and not associated with any geologic fractures. This work is about understanding the macro-mechanical properties of sandstones by studying several petrographic parameters, which could provide evidence of their influence on mechanical strength. Here the authors were considered the Bhuban sandstones of western Indo-Burmese Ranges (IBR) of north-eastern India to investigate the above criteria. The result shows that sandstones have a mean grain size between 108 to 208 µm. Moderate to poorly sorted (phi scale ranges 0.56-1.5) grains show greater content of rounded constituents (43-68 %) with sphericity between 0.65-0.85; along with moderate packing properties (packing density 54-77 %; packing proximity 32-70 %). The grains join by mostly straight (20-54 %) and concavo-convex (13-45 %) contacts; with lesser point (5-13 %) and sutured contacts (8-44 %). Schmidt Hammer rebound values (R-values) were used to calculate and analyse the uniaxial confined stress (UCS); which again validated with UCS testing of core samples. The comparison between macro-mechanical parameters and the UCS shows interrelationship among rock constituents which hold the key to the mechanical strength of the rock. The presence of angular grains and semi-angular spherical grains diminish the macromechanical strength to some extent. Moreover, FETEM-EDX analysis confirms the microweathering of the angular grains, which have a deformed lattice setting. These findings show that macro-mechanical and micro-nano scale properties of sandstones influence the rock strength. [ABSTRACT FROM AUTHOR]

This study presents the results of geochemical investigations of early to middle Eocene sandstones belonging to the Dalbuing Formation of Yinkiong Group, occurring in and around Yamne valley of Arunachal Pradesh. Geochemically, these sandstones are wacke and lithic arenite, with the former being dominant than the other. The various indices of weathering (CIA, CIW, PIA) suggest intense chemical weathering of the source rock. Moreover, the average Th/U ratio (mean = 6.97) also indicates intense chemical weathering in the source areas and derivation of the sediments from the upper continental crust. However, the plot of chemical index of alteration (CIA) vs. index of compositional variability (ICV) shows that most of the sandstones are geochemically mature and were derived from intensively weathered source rock. The sandstones were deposited dominantly in semi-arid condition. Tectonically, these sandstones are found to have affinities towards both the passive margin (PM) and the active continental margin (ACM) settings, which further implies existence of multiple tectonic activities during their deposition. Moreover, the elemental ratios of Eu/Eu*, La/Sc, Th/Sc, La/Co, Th/Co, Th/Cr and chondrite normalized REE distribution pattern suggest their derivation from sources of felsic composition. The high ratio of Zr/Sc indicates the enrichment of heavy mineral zircon supplemented by sediment recycling. [ABSTRACT FROM AUTHOR]

In the present work, geological, geotechnical, and ground penetration radar studies were carried out along the Mansa Devi hill bypass (MDHB) road Uttarakhand, India in order to assess the slope instability conditions. Seven unstable zones along the entire MDHB road were identified which are prone to landslides. Geologically, the area is composed of mudstone and sandstone with thick overburden constituting sandy soil. The laboratory tests were carried out in order to evaluate the geo-mechanical characterization of soil, sandstone, and mudstone that constitute the slopes. The laboratory tests reveal that the slope is comprised of soil characterized by high permeability and low strength values. The soil is mainly sandy and non-cohesive. The laboratory tests on sandstone reveal that fresh sandstone exhibits exceptionally higher value of unconfined compressive strength (> 100 MPa) than the weathered sandstone (< 35 MPa). The mudstone is non-durable and contains considerable amount of expanded clay minerals which has a tendency to expand in the presence of water. It can weather easily and facilitate instability at shallow depth. A ground penetrating radar survey confirmed that the road is unstable particularly on those spots where the road either lying over mudstone beds or over thick non-cohesive sandy soil. The infiltration rate of water in this sandy soil is generally rapid which allows fast flow of water into the deeper horizons and thus cracks can be seen in road caused by vertical settlement. Similar results are observed in slope stability analysis where the slope covered with sandy soil exhibits factor of safety less than 1.0. However factor of safety is close to 1 where the slopes consist of alternate beds of sandstone and mudstone. [ABSTRACT FROM AUTHOR]

Context: Silicosis is a progressive, irreversible and incurable respiratory morbidity and often becomes a cause for pre-mature mortality among occupationally silica dust-exposed workers in India and similar countries. It has a dual problem of associated silico-tuberculosis as a co-morbidity. The present study was done to assess the respiratory morbidity caused by silicosis in sandstone mine of Rajasthan, India. Methods: The chest X-rays of 529 subjects having history of employment in stone mines with respiratory morbidity were subjected for this study and evaluated in accordance with ILO Classification 2000. The X-rays were classified into various categories of silicosis and progressive massive fibrosis (PMF) in relation to years of work in stone mines. Results: Out of 529 chest radiographs evaluated, 275 (52%) showed radiological evidence of silicosis. Of them, 40 (7.5%) subjects showed large opacities suggestive of progressive massive fibrosis. Both silicosis and progressive massive fibrosis were associated with increasing duration of work in stone mines. Sixty-one (12.4%) subjects with silicosis also had associated pulmonary tuberculosis, termed as silico-tuberculosis. Conclusion: The present study showed a high prevalence of silicosis, progressive massive fibrosis and silico-tuberculosis among stone mine workers. It appears that that unless silicosis is controlled, elimination of tuberculosis is far from reality in the country. Hence, states and central authorities must work together towards control of both silicosis as well as silico-tuberculosis. Similarly, there is an urgent need of initiation of national silicosis control programme, similar to existing national tuberculosis control programme, considering the huge burden of silicosis in India [ABSTRACT FROM AUTHOR]

Thin‐section petrography, scanning electron microscopy (SEM) and X‐ray diffraction (XRD) analyses are applied to investigate the various diagenetic controls on the reservoir quality of the Ridge and Athleta Sandstone members (Chari Formation) of the Jara dome, Kachchh Basin, western India. The results show that the sandstones of Jara dome are quartz‐arenite to sub‐arkose, medium‐ to coarse‐grained, sub‐angular to sub‐rounded, poorly to moderately well‐sorted and having low‐ to medium‐sphericity. Diagenetic features such as mechanical compaction, pressure solution, cementation, and dissolution of unstable framework grains are analysed to synthesize the reservoir characteristics. The principal cementing materials are carbonates, iron oxides, silica overgrowth, and authigenic clays, mainly chlorite and kaolinite. Compaction and cementation are the controlling factors for the reduction in porosity and permeability of the sandstones. Dissolution of detrital feldspars is the main cause of porosity enhancement in these sandstones. The relationship between the intergranular volume (IGV) and cement volume indicates that cementation had played a more important role in the destruction of primary porosity than that of compaction. On the one hand, the ubiquitous development of carbonate cement advocates the loss in primary porosity at the early stage of diagenesis, while on the other hand it also prevented the further compaction of sandstone, thus preserving unfilled voids as primary porosity. Precipitation of carbonate cement is followed by development of pore‐lining and pore‐filling clayey cements. The pore‐filling kaolinite resulted in a considerable loss of porosity while the pore‐lining chlorite has helped in retaining the porosity by preventing syntaxial silica overgrowths. The reservoir quality of the studied sandstone is reduced by the authigenic clay cements, early carbonate precipitation and silica overgrowths, nonetheless, it is improved by the dissolution and alteration of unstable grains, in addition to partial dissolution of carbonate cements. The potential of the studied sandstone to act as a reservoir is strongly related to sandstone diagenesis. [ABSTRACT FROM AUTHOR]

Soft‐sediment deformation (SSD) structures are the syn‐sedimentary structures that can form by seismic as well as non‐seismic processes. The SSD structures commonly occur in the Semri Group of the Vindhyan Supergroup in the Kajrahat Limestone, Chopan Porcellanite and Rohtas Limestone formations, and the Glauconitic Sandstone Member. The SSD structures include, slump folds, kink bands, chevron folds, convolute beddings, contorted cross‐beds, flame structures, pinch‐and‐swell structures, breccias, sagging structures, water‐escape structures, and dykes of varying dimensions. The lagoonal and tidal depositional environments of the Kajarahat Limestone Formation (not the continental slope environment) lead to suggest that the SSD structures formed as a result of the seismic activities in them. The SSD structures of the Chopan Porcellanite Formation associated with rhyolite might have originated as a result of volcanic activities or seismicity, while those occurring in the Glauconitic Sandstone Member (Kheinjua Formation) adjacent to the Son Lineament might have formed as a tectonics‐related seismicity. The convolute bedding with large lateral extent in the Rohtas Limestone Formation looks related to seismicity in the light of its deposition along the shelf. Thus, the upper Palaeo‐Mesoproterozoic Semri Group, Vindhyan Supergroup represents varieties of the SSD structures formed mostly by seismic processes. These imply that the Central India was unstable and was a place for tectonically controlled seismic events during the upper Palaeo‐Mesoproterozoic (1,700–1,600 Ma). [ABSTRACT FROM AUTHOR]

A crack system found developed on the surface of sandstone belonging to Bhuban Formation of Surma Group near Vanchengpui village in Mizoram. These polygonal crack system with circular or disc shape cracks overlapping one another are the conspicuous characteristic feature representing their process of formation. The crack system is developed on the domal surface of the exposed bed-rock and are limited to the top thin layer. The thickness of crack bearing layer varies from 3 to 13 cm and the cracks maintain perpendicular relationship with the slope surfaces. Field investigations and analysis of the crack present in the area reveals that the crack system developed in the sandstone are due to weathering processes coupled with compressive stresses. [ABSTRACT FROM AUTHOR]

Discs/discoidal body fossils, an important constituent of Ediacaran biota, are reported from the sandstone unit of the Hotpet Formation of the Bhima Group, South India. Nine specimens preserved as circular to ovate structures are described and attributed to Ediacaran discs and are akin to Fermeuse-style preservation of Ediacaran fossils. These discs, occur as impressions on the bedding planes, are referred as Charniodiscus-like fossils. This is the first report of Ediacaran discs from the Bhima Group, south India. [ABSTRACT FROM AUTHOR]

Background: In Indian mines, the prescribed exposure limit (PEL) for free silica dust is 0.15 mg/m3 which is much higher than those of OSHA and the ACGIH. Because of the reporting of high numbers of silicosis cases among Indian sandstone mine workers, the present study was designed to assess the dust exposure profile of the workers and to substantiate correlation of silica exposure with radiographic findings of silicosis. Methods: A cross‐sectional study of 1012 workers actively engaged in sandstone mining was conducted. Chest x‐rays were evaluated by the ILO Classification for the detection of pneumoconiosis. Representative 26 personal dust samples were collected using a personal dust sampler and free silica content estimated. Results: Radiographs compatible with silicosis were seen in 12.3% of workers, of which about 90% were ILO category 1 & 2. Prevalence of abnormal profusion increased from 2.9% to 13.1% to 22% as work exposure increased from <10 to 11 to 20 to >20 years, respectively. In dust samples, the mean silica concentration was 0.12 mg/m3 with 70% samples below the prescribed standard of 0.15 mg/m3. Conclusion: The study indicates that silica exposure below the prescribed limit in India is likely to be harmful. The PEL for crystalline silica in India of 0.15 mg/m3 is not adequately protective. Hence, there is an urgent need to reduce exposure to silica in these workplaces to prevent silicosis and to review the present standards as the government of India remains committed to the elimination of silicosis by 2030. [ABSTRACT FROM AUTHOR]

Sandstones belonging to the Oligocene Barail Group and Miocene Surma Group of the Mizoram Foreland Basin have been studied geochemically to constrain their provenances, tectonic setting, and other sedimentary processes (weathering and mineral sorting etc.). Based on their mineralogical compositions, these sandstones are classified as quartzarenite and sublithic-arenite. The sandstones of Barail and Surma Groups have similar contents of most of the major elements except for SiO2 and Al2O3. The Barail sandstones are relatively more siliceous and less aluminous compared to the Surma sandstones. Barail and Surma sandstones were plotted in a singular array on different geochemical discrimination diagrams. The CIA and CIW values of the sandstones of Barail (69 and 77 respectively) and Surma Groups (68 and 77 respectively) suggest that the sandstones were derived from moderately weathered source rocks. In the A–CN–K diagram, the studied samples plotted along a roughly singular trend that originates from granodiorite as well as Trans-Himalayan granitoids and also confined within the field of Siwalik sediments. Chondrite-normalized REE patterns for the Surma and Barail sandstones are identical and are similar to upper continental crust, with moderate to high LREE enrichment and prominent negative Eu anomalies (Eu/Eu* for both Barail and Surma sandstone = 0.69), indicating their derivation from a felsic magmatic source. The values of Eu/Eu*, (LaN/LuN), La/Sc, La/Co, Th/Sc, Th/Co, and Cr/Th ratios of Surma and Barail sandstones are also not significantly different, and the values are similar to fine-fractions derived from the weathering of felsic rocks. In the K2O/Na2O versus SiO2, Th–Sc–Zr/10 and Ti/Zr versus La/Sc tectonic discrimination diagrams the studied samples of Barail and Surma sandstones plot within the fields of greywacke from continental island arcs and active continental margin. The geochemical characteristics of the studied sedimentary rocks and their similarity with the Siwalik foreland sediments thus suggest were sourced from different felsic magmatic lithounits of Himalaya and were deposited in an active continental margin. [ABSTRACT FROM AUTHOR]

Located within the centre of the Tethys Himalayas, the Weimei Formation of the Rongbu area in southern Tibet is a littoral- neritic sedimentary association composed of clastic rocks and a few shales. Petrologic characteristics and detrital component statistics indicate that sandstone types include lithic quartz sandstones, with the average content of quartz, feldspar and debris being 77%, 9% and 14%, respectively. The provenance of the Weimei Formation is a recycled orogeny, and the aforementioned sandstones generally have high SiO2 levels, low CaO, K2O and Na2O levels and wide ranges of CIA and CIW values. The primitive mantle-normalised trace element spider diagrams showed unstable content of some elements and losses of Ba, P, Sr, K, Ti and other elements in partial samples. Chondrite-normalised rare-earth element (REE) patterns indicate that the sandstones are characterised by an enrichment of LREE, significant fractionation of LREE and HREE and negative Eu anomalies. Further, ratios of Sm/Nd and Cr/Zr and discriminant diagrams (i.e., La/Yb versus ΣREE, ΣREE versus SiO2/Al2O3, La/Th versus Hf and function discrimination diagrams) reveal that sandstones from the Weimei Formation were derived from ancient quartzose sedimentary rocks and volcanic rocks of continental island arc. Many important parameters (i.e., La, Ce, Pb, Th, Hf, Zr, ΣREE, La/Yb, (La/Yb)N, ΣLREE/ΣHREE, Eu/Eu*, Rb/Sr and Zr/Hf) of samples and tectonic setting discriminant diagrams (i.e., Th versus Co versus Zr/10, La versus Th versus Sc, La versus Th and function discriminant diagrams) indicate that the tectonic setting of the Weimei Formation sandstones from the Tethys Himalayas has both characteristics of a passive margin and continental island arc. By comparing the detrital zircon U-Pb ages and Hf isotopic characteristics of the Weimei Formation with the strata whose provenances have been identified and analysing the weathering, petrography and geochemistry characteristics of Weimei Formation sandstones and the paleogeography conditions of the northern margin of the India craton within the Late Jurassic epoch, we inferred that Weimei Formation sandstones were mainly sourced from the Precambrian metamorphic rocks of the India craton, simultaneously, the sandstones also received minor sedimentary materials from earlier Tethys Himalaya strata whose provenances contained volcanic rocks of the nearby Gangdese volcanic belt. After experiencing weak to moderate weathering, denudation and long-distance transport, the sedimentary materials eventually migrated to the shelf and the top of the continental slope on the northern margin of the Indian continent, where the materials later participated in diagenesis. [ABSTRACT FROM AUTHOR]

Background: This study was carried out to assess the reach of medico-social and economic programs to the silicosis victims in Karauli. The district is infamous for large-scale unregulated sandstone mining, a pulmonary hazard, causing silicosis, a debilitating occupational disease compensable under Indian laws. Methodology: A sample of 250 silicosis cases from 38 villages were randomly recruited and interviewed from four different sites. Results: The study reports that 99% of sandstone miners came from marginalized poor communities, had large families, and lived in mud houses. Victims' linkage to their entitlements and welfare programs was poor (51%). Victims (43%) continue to work as casual laborers including in mining sector due to economic compulsions. Greater than 68% of the laborers were wrongly treated for tuberculosis (TB) prior to their diagnosis, >50% go out of the state or cities for better treatment, and 60% of cases had not received their compensation from the government. Among those who received compensation, only 4% spent money for productive purposes and 44% victims were not in a position to work due to health difficulties. Conclusions: Silicosis has affected the poorest of the poor; victims are wrongly diagnosed and treated for TB. The district is not equipped to deal with the health problems of the victims, forcing them to seek treatment in other states and cities. In conclusion, the impact of rehabilitation programs in the district is ineffective and inadequate and has limited reach. Findings of the study will have far-reaching implications for informed policymaking on the rehabilitation of silicosis victims in the state. [ABSTRACT FROM AUTHOR]

Detrital mineralogy of the sandstone of Fort Member of Jurassic Jaisalmer basin has been investigated with respect to provenance, the influence of palaeoclimate, distance of transport and effects of diagenesis on the detrital mineralogy. Petrographic studies based on quantitative analysis of the detrital minerals revealed that the sandstones are composed mostly of quartz, feldspar, mica, chert, rock fragments and heavy minerals. The detrital modes of the studied Fort Member sandstone, which are indicative of mature stable cratonic blocks and recycled orogen provenance, where sediments are likely to be derived from collision orogen under semi-humid to humid climatic conditions. Petrographic data coupled with the palaeocurrent analysis results indicate a mixed provenance including granites, granite-gneisses, low and high-grade metamorphic rocks of the Aravalli craton. [ABSTRACT FROM AUTHOR]

The objective of this study is to highlight main causes of flexibility in itacolumite from Kaliana Hills, Charkhi Dadri district, Haryana. Results of petrominerological studies, scanning electron microscopy (SEM), 3D analysis of SEM images, and quantitative micro fabric analysis reveal that the intergranular void spaces are significantly higher in more flexible specimen (mean 47.68 μm) relative to less flexible specimen (mean 14.32 μm, i.e., <3 times), whereas, non-flexible sandstones show negligible intergranular void spaces (4.97-6.40 μm). Therefore, it may be envisaged that the flexibility in Kaliana itacolumite is due to the presence of more intergranular void spaces. The chemical corrosion appears to be the main reason for the formation of more void spaces in between the constituent grains in the flexible sandstones. Leaching effect on the grains is evident on scanning electron microscopic (SEM) images. These solution channels and embayment might have removed the significant amount of cementing material and silica by dissolution and solution activity. Thus, obviously, the flexibility in the itacolumite was induced by solution activity, more the solution activity, more the void spaces and hence more resultant flexibility. Almost vertically dipping beds of sandstone would have facilitated capillary movement and solutioning leading to development of concomitant leaching induced porosity.Higher degree of flexibility in itacolumite specimen from quarry dump, compared to in-situ fresh itacolumite specimen, is apparently due to more exposure of former to surface processes like weathering, more solution activity and corrosion leading to more removal of cementing material and silica accompanied by concomitant augmentation of considerable intergranular void spaces (>3 times), relative to the latter. It is thus clear that relatively less flexibility in in-situ itacolumite is linked with its less solutioning relative to itacolumite from dump. Thermal shock resistance property of itacolumite can be used as a model material to process synthetic flexible ceramics by mixing phases with large differences of thermal expansion properties. [ABSTRACT FROM AUTHOR]

Kalijhora in Darjeeling district of West Bengal happens to be one of the few places in extra-peninsular India which hosts Gondwana rocks. While Gondwana sedimentation in peninsular India largely took place within a fluviatile regime, marine influences on these rocks have been proved from some areas of Himalayan region mainly based on paleontological attributes which are absent in Kalijhora. The Kalijhora lithostratigraphic column which exudes imprints of Himalayan geodynamism is largely arenaceous with minor carbonaceous shale, sandy shale and coal. These arenaceous units were investigated in detail to locate marine signatures, if any. The sub-arkose to sub-litharenite Kalijhora sandstones having more of calcareous cements show imprints of locomorphic to phyllomorphic stages of diagenesis. Mg/Ca ratio of Kalijhora sandstones hints at possible precipitation of low to high magnesian calcite under a marine influence. The presence of dolomite in pore spaces and the dolomitic accretions in the form of stars indicate a phase of dolomitic intrusion which is a distinct marine signature. Further, both primary euhedral dolomite cement crystals and secondary dolomitized cements represent two phases of cementation that can be inferred to have formed during a possible marine incursion phase as seawater is the common and principal source of Mg in sediments. [ABSTRACT FROM AUTHOR]

Chorar Island exposes ∼109 m thick middle Jurassic (Bathonian-Callovian) succession in the eastern most part of the Kachchh Basin, Patan District, Gujarat and is divided into two, Khadir and Gadhada formations. It mainly comprises of mixed siliciclastic-carbonate sediments and limestones; the shales dominate the lower part of the succession while the top of the succession is marked by ferruginous sandstone which also forms the vast, prominent peripheral zone of the Chorar dome. The field and laboratory analysis of the succession reveals nine lithofacies which includes ferruginous sandstone, cross bedded white sandstone, micritic sandstone, allochemic sandstone, sandy micrite, mudstone, sandy allochemic limestone, coralline limestone and shale. The mix siliciclastic-carbonate sediments and ferruginous facies are fossiliferous in nature and display sedimentary structures, like ripple marks, cross- and planar- lamination with biogenic sedimentary structures. Coralline limestone facies comprise of large size (>1m diameter) corals, which are diagenetically modified severely and have lost its original internal structures. The sediment characteristics and associated bioclasts indicates low to moderate wave and current energy in shoreface-offshore subsequently changing to wave dominated shoreface during the deposition of the middle Jurassic sediments of the Chorar Island. [ABSTRACT FROM AUTHOR]

Sandstone-mudstone interfaces offer an excellent medium for the preservation of the burrows. This study discusses the morphology, ecological niche and correlation based of 291 Treptichnus pedum specimens of the lower Cambrian Nagaur Sandstone, western Rajasthan, India. Petrological attributes of the host sediment are also addressed. Statistical analyses of size (length, width and gap of each segment of T. pedum) were conducted to determine the inter-specific variation. Data suggest that the entire Nagaur assemblage was made by one major group of makers. Overall morphology suggests that these burrows were probably made for shelter and trapping small epibenthic or endobenthic organisms. An overview of the global occurrence of T. pedum shows broad environment tolerance. The Nagaur specimens are compared with various recorded occurrences of T. pedum to assess the nature of the plausible producer organism, its behaviour and taphonomical aspects. [ABSTRACT FROM AUTHOR]

Within the hydrocarbon-producing Cretaceous marine Uttatur Group, Cauvery Basin, India, the Garudamangalam Sandstone Formation is at top of a TST-HST transit. The δ 13 C value is expectedly depleted within the calcareous Garudamangalam Sandstone, which is the top most unit of the Uttatur Group, overlying the Karai Shale. The calcareous sandstone was deposited in a coastal setting around a shore-parallel river mouth bar. Instances of excessive depletion of δ 13 C up to −44.5‰ in the carbonate cement is suggestive of methane generation and its subsequent sequestration. The common occurrence of early diagenetic pyrite in these rocks testifies to the proliferation of sulfate-reducing bacteria and is suggestive of methane generation beneath the sulfate reduction zone. Upward-moving diffusive methane was possibly consumed by methanotrophs at the base of the sulfate-reduction zone. Abundant fabric-selective carbonate cement corroborates microbially-controlled anaerobic oxidation of methane. The presumed high rate of nutrient supply, abundance of vegetative material and moderately high organic carbon content in sediments (av. 1.6%), support this contention. All the samples which have the greatest δ 13 C depletion are characterized by enriched organic carbon and are derived from a tidal inlet-mouth facies, and selectively from mud drapes on cross-bedding in tidal strata. Calcarenite at the base of the same cross-strata are invariably much less depleted in δC 13 . This range of relationships indicates the transport of methanotrophs that settled on foreset beds mostly as tides slackened under the broader control of neap-spring cycles. [ABSTRACT FROM AUTHOR]

Biogenic signatures in Precambrian rocks are often difficult to confirm and debatable. We present some unusual features associated with microbial-mat related structures (MRS) from the freshly-exposed rippled bed surface of 1.6 Ga old Chorhat Sandstone, Vindhyan Supergroup, India. The features discussed here, are present within intertidal to supratidal environments often affected by storms. One of the features includes ridge-groove couplets that run across the ripple crests. Locally, the ridge-groove couplet forms a braid-like pattern. Along the ripple troughs, the ridges are considerably long and maintain a uniform width on the mm scale. Another feature shows meandering grooves bordered by ridges. The grooves swerve, form loops, cut across older grooves, and branch up. None of them have comparable equivalents in the Precambrian record described thus far. The invariably uniform width of the ridges for both the two features cannot be compared with undersurface gas bubble migration, and the swerving and reversing nature of the grooves denies passive movement of any inorganic/organic masses under the influence of an external force. They seem to have been created by movement through a microbiota-rich surficial sediment. Such unusual features raise questions about the biosphere and biotic structures during the Boring Billion (1.8–0.8 Ga). [ABSTRACT FROM AUTHOR]

The present study discusses the origin and affinity of enigmatic Ediacaran bedding plane structures reported earlier from the Sonia Sandstone of the Marwar Supergroup (Ediacaran to Lower Cambrian). These forms are conspicuously large, non-carbonaceous and three-dimensionally preserved. Morphologically, these structures are not comparable with any known plant/animal fossil, trace fossil, microbially induced sedimentary structures (MISS) found in the Ediacaran assemblages or any other extant forms and are invariably associated with MISS. Past researches on these fossils did not resolve their affinity, form and function. The present forms have certain features akin to seaweed organization such as thallus, loop pattern within the thallus, variously positioned nodes/swellings, tapering at the end of thallus, branching pattern and rarely occurring holdfast-like features. Systematic description, incorporating detailed morphological features, population size, their relationship with associated sediments and stratigraphic distribution, is based on the study of 54 specimens. Subtidal to intertidal models of depositional sedimentary environment, palaeoecology, biogenicity, affinity, taphonomic changes, association of these forms with MISS and other parameters are also discussed. A succession of plausible interpretations is offered; seaweed is the most likely interpretation. The Marwar Supergroup, thus, unravels some of the hitherto enigmatic forms of the Ediacaran Period (635-541 Ma). Copyright © 2016 John Wiley & Sons, Ltd. [ABSTRACT FROM AUTHOR]