Lameta Sediments Research Articles

Record of calcareous algae from the Lameta Formation: a new insight for possible sea incursion during the Maastrichtian time

The Lameta Formation exposed in central and western India is traditionally considered as deposits of fluvio-lacustrine environment except for the type area having a few reports of shallow marine setting. The present work records the fossilization of calcareous algae from a discontinued bed of limestone preserved in argillaceous unit of Lameta succession. Taxonomical study of algal biota places them mostly in chlorophyta, charophyta, and rhodophyta divisions. These algae are being reported for the first time from Lameta sediments of a newly identified inland basin of deposition, viz., Salbardi-Belkher. Considering the paleoecological significance of presently recorded algae, a marine incursion has been interpreted which might have taken place through the Narmada-Tapti Rift Zone during the Maastrichtian time.

Microflora from Sauropod Coprolites and Associated Sediments of Late Cretaceous (Maastrichtian) Lameta Formation of Nand-Dongargaon Basin, Maharashtra

Abstract Micofloral study of Lameta sediments and associated sauropod coprolites in the Nand-Dongargaon basin in Maharashtra was conducted to understand the diet and habitat of sauropods. The study revealed the presence of pollen, spores, algal and fungal remains, well-preserved cuticles of Poaceae, and testate amoebae. Vegetation during Lameta included tall arboreal taxa, such as conifers (Podocarpus and Araucaria), Cycads (Cycas), Euphorian and Barringtonia and herbs and shrubs, such as Cheirolepidiaceae (Classopollis), Arecaceae (Palmaepollenites), Poaceae (Graminidites), Asteraceae (Compositoipollenites), Caryophyllaceae (Cretacaeiporites and Periporopollenites), and Acanthaceae (Multiareolites). Data suggest that the sauropods ate soft tissues of angiosperms and gymnosperms. The intake of testate amoeba, algal remains, sponge spicules, and diatoms might be through water intake.

Palaeoenvironmental changes associated with Deccan volcanism, examples from terrestrial deposits from Central India

We analysed the geochemical and mineralogical aspects of sedimentary beds associated with Deccan volcanism exposed in the eastern part of the volcanic sequence in the Jabalpur–Mandla–Chhindwara (JMC) sector (Madyha Pradesh) and in the Nand–Dongargaon (ND) basin in Central India. These sediments were deposited in terrestrial environments before the onset of the volcanic activity or during periods of quiescence in mainly alluvial-limnic to lacustrine facies. Deposited at different stratigraphic levels within the Deccan lava pile, they provide crucial evidence to evaluate environmental changes on land induced by the onset of the volcanism in the central part of India. Our results indicate that sediments (intertrappeans) deposited during Deccan volcanism do not reflect the same depositional characteristics as sediments (Lameta Formation) preceding volcanic eruptions. The sedimentological and mineralogical observations indicate alluvial-limnic environments under semi-arid climate during deposition of the Lameta sediments. This could explain the low concentration of organic matter, which probably underwent excessive desiccation/oxidation processes under semi-arid conditions. The eruption of Deccan volcanic flows severely affected environmental conditions. Intertrappean sediments associated with Deccan phase-1 and phase-2 were deposited in terrestrial to lacustrine environments under semi-arid climates with dry and humid seasons, which are highlighted by the predominance of smectites resulting from basalt alteration. Organic matter is well preserved in the sediments deposited in phase-1 and indicates a mixed source with well-preserved lacustrine organic matter and terrestrial inputs. The subsequent intertrappean sediments within phase-2 are strongly influenced by Deccan volcanism characterized by high volcanic content associated elements (Ti and Fe) and high chemical alteration (CIA-K) that likely reflects increasing acid rains rather than climatic change. In addition, a sharp decrease in pollen and spores coupled with the appearance of fungi mark increasing stress conditions, which is likely a direct result of volcanic activity. Bulk organic geochemistry points to a strong degradation of the autochthonous organic matter, suggesting that the biomass was oxidized in acidic conditions triggered by intense volcanic activity.

Upper Cretaceous (Maastrichtian) Charophyte Gyrogonites from the Lameta Formation of Jabalpur, Central India: Palaeobiogeographic and Palaeoecological Implications

Abstract A charophyte gyrogonite assemblage consisting of Platychara cf. sahnii, Nemegtichara grambastii and Microchara sp. is reported herein from two localities (Bara Simla Hill and Chui Hill sections) of the Lameta Formation at Jabalpur. he Lameta Formation locally underlying the Deccan traps has been shown to be pedogenically modified alluvial plain deposits containing one of the most extensive dinosaur nesting sites in the world. They are associated with dinosaur bones and freshwater ostracod assemblages that suggest a Late Cretaceous (Maastrichtian) age. This is the first detailed systematic account of charophyte gyrogonites from the Lameta Formation. This charophyte assemblage is compatible with the biostratigraphic attribution provided by the ostracods. From a biogeographic viewpoint, it exhibits considerable similarity to other infratrappean assemblages of the Nand, Dongargaon, and Dhamni-Pavna sections (Maharashtra), and some intertrappean assemblages of Kora in Gujarat, Rangapur in Andhra Pradesh and Gurmatkal in South India. Globally, the genus Microchara is well distributed throughout Eurasia, whereas the genus Platychara occurs richly in the Upper Cretaceous deposits of Europe, Asia, America and Africa. However, at the specific level, Platychara cf. sahnii shows close affinities with charophytes from the Maastrichtian of Iran whilst Nemegtichara grambastii shows distinct affinities with two species of Early Palaeogene deposits of China and Mongolia. The presence of charophyte gyrogonites in the Lameta sediments is attributed to local lacustrine and palustrine conditions within a flood plain environment.

Lithofacies architecture and depositional environment of Late Cretaceous Lameta Formation, central India

Establishment of lithofacies and interpretation of depositional environment of the Lameta Formation have been carried out for a new area having three nearby exposures. Overall, the successions are broadly differentiable into three major units, i.e. arenaceous in the lower part, argillaceous in middle and calcareous at the top, which more or less serve as three lithofacies associations. Each association consists of various lithofacies which are identified and established on the basis of field observations, added with significant petrological details. The arenaceous association includes five lithofacies, viz. massive sandstone lithofacies; green sandstone lithofacies; thinly bedded, yellowish orange and greyish brown sandstone lithofacies; coarse-grained sandstone lithofacies and dark brown bioturbated sandstone lithofacies. The argillaceous lithofacies association consists of yellowish-brownish-greenish clay–siltstone lithofacies and light grey silty–clay with concretions lithofacies, whereas the calcareous lithofacies association is represented by calcrete lithofacies, nodular limestone lithofacies, chertified limestone lithofacies and intraformational breccia lithofacies. The facies analysis reveals that the deposition of Late Cretaceous Lameta sediments took place in fluvial–lacustrine environments in semi arid condition.

Trace fossils and their palaeoenvironmental significance in the Lameta Formation of Salbardi and Belkher area, district Amravati, Maharashtra, India

Trace fossils namely, Planolites, Planolites montanus, Thalassinoides and stuff burrows belonging to the Lameta Formation of Central India are reported for the first time from two new localities, i.e., Salbardi and Belkher area. Both the exposures are well represented by the typical marker lithounits as of Jabalpur, Nand-Dongargaon area of central India, i.e., greenish yellow sandstone, clays of various shades, chertified and brecciated limestones, etc. These successions are devoid of megaforal remains, therefore, these biogenic structures play a significant role in the interpretation of palaeoenvironment and palaeoecology during the deposition of the Lameta sediments. The trace fossils assemblage shows that the benthonic community was mainly polychaetes and crustaceans.

Site amplification studies towards seismic microzonation in Jabalpur urban area, central India

Site amplifications at over 100 sites in the frequency range of 0.1–10 Hz were investigated in and around Jabalpur city of central India using the conventional Nakamura technique of computing H/ V spectral ratios, to estimate the predominant frequencies and corresponding amplifications at each site. To validate these results, Multichannel Analysis of Surface Waves (MASW) technique was adopted, coupled with refraction measurements over short profiles (∼100 m) resulting in detailed images of shear wave and primary wave velocity structure of the shallow subsurface as well as the depth to basement, which are crucial for estimation of the amplification of seismic signals propagating through the medium. Synthetic seismograms generated based on these detailed structural models using a hybrid method comprising normal mode summation for the regional 1D structure and finite difference approach for site specific 2D structure of the medium are used to compare with site response results from the Nakamura approach. The local site amplifications expressed as the response spectral ratios – the ratio of 2D to 1D ground acceleration response-compare fairly well with the H/ V results enabling proper interpretation of the composition and thickness of the upper soil cover and its hazard potential. The most significant amplification values are seen over the alluvial filled region in the north-western part of Jabalpur having soil thickness up to 30–50 m, with amplifications ranging from 4.0 to 6.0, predominantly in the frequency range of 4–5 Hz. Also, the areas covered with Lameta sediments in the west and northeast have thicker soil cover and indicate amplifications twice that of the adjoining Deccan trap areas. The Gondwana sediments are an exception where, in spite of thick soil covers, lower amplification values are observed which are about half of that in the alluvial regions with similar thicknesses. This is probably due to the compactness of the sedimentary formations in the former as compared to the loose, low velocity and low density alluvium in the latter. The study indicates the importance of a multi-disciplinary approach for better understanding the site amplification characteristics in any seismically active region.

Palynoflora from deccan volcano-sedimentary sequence (Cretaceous-Palaeogene transition) of central India: implications for spatio-temporal correlation

The sedimentary beds associated with Deccan Continental Flood Basalt (DCFB) sequences exposed in the volcanic subprovinces of Jabalpur-Mandla-Chhindwara (JMC) regions of Madhya Pradesh and Nand-Dongargaon (N-D) basin and the adjoining areas to the west in Yeotmal-Nanded in Maharashtra were studied for their palynofloral analysis. The sediments were characterized palynologically and changes in the palynoflora are observed at different stratigraphic levels in a number of sections including several new intertrappean localities recorded in recent years. For the purpose of effective correlation of different subprovinces, palynofloras of some of the previously studied intertrappeans are also reviewed. Our studies suggest that before the start of the Deccan volcanic activity, the palynoflora found in the Lameta sediments, was dominated by gymnosperms-angiosperm association. The plant canopy consisted mainly of gymnosperms (Conifers and Podocarpaceae) whereas, the understory members were mostly of palms and herbs (Poaceae and Asteraceae). The eruption of Deccan volcanic flows severely affected the existing floral association and proved fatal for the well established plant community. The immediately overlying sediments associated with the earliest volcanic flows are dominated by pteridophytes and angiosperm taxa (Azolla cretacea, Aquilapollenites bengalensis, Ariadnaesporites sp., Gabonisporis vigourouxii and Triporoletes reticulatus). Higher up in the stratigraphic sequence, similar forms continued with simultaneous appearance of new taxa including Scabrastephanocolpites spp. At still higher stratigraphic levels, abundance of fungi especially the mycorrhizal fungi, concurrent with sharp decline in pollen/spore recovery was observed. In the culminating phase (i.e. Palaeocene) of Deccan volcanic history a new palynofloral assemblage of typical Palaeocene taxa (Dandotiaspora dilata, D. pseudoauriculata, D. plicata, Spinizonocolpites echinatus, Matanomadhiasulcites sp., and Lakiapollis ovatus) was encountered.

No K/T boundary at Anjar, Gujarat, India: Evidence from magnetic susceptibility and carbon isotopes

The paper describes the variation pattern of magnetic susceptibility of Lameta sediments and isotopic variation of organic13C from Chui Hill, Bergi, Kholdoda, Pisdura and Girad. The susceptibility pattern and a negative carbon isotopic anomaly allows fixation of the K/T boundary at these localities and they differ in these aspects from the inter-trappean sediments at Anjar.Paleomagnetic measurements of the Anjar sediment and the overlying basalt flow demonstrate reversed polarity. The Lameta sediments with dinosaur nests at Kheda and the overlying intertrappean sediments are of normal polarity.The clay layers at Anjar, associated closely with Ir-enrichments, are strongly leached, rhyolitic bentonites containing low-quartz paramorphs after high-quartz with glass inclusions.It is concluded, that the inter-trappean lake deposits at Anjar were deposited in the early part of magnetochron 29R and are unrelated to the K/T boundary.

Similarities in the mineralogical and geochemical attributes of detrital clays of Maastrichtian Lameta Beds and weathered Deccan basalt, Central India

Mineralo-chemical attributes of the Maastrichtian (Late Cretaceous) Lameta sediments, intimately associated with the Deccan Traps in Central India, provide insight into the initiation of Deccan volcanism. X-ray diffraction studies on the detrital clays of the Lametas and weathered Deccan basalt show identical mineral assemblages with the dominance of smectite and subordinate kaolinite, illite. IR spectra are also indicative of their common mineralogical attributes. Structural formulae of the smectites in Lameta exhibit high octahedral Mg and Fe. The immobile trace-element concentrations in Lameta clays resemble those in weathered Deccan basalt. REE plots of the Lametas are subparellel with that of weathered Deccan basalt and show negative Ce anomalies documented in basalt weathering.These findings suggest that smectite-rich clays of the Lametas are derivatives of the Deccan basalt, implying early activities of Deccan volcanism either during or just prior to the Maastrichtian Lameta sedimentation.

Composition of Smectites in the Lameta Sediments of Central India: Implications for the Commencement of Deccan Volcanism

Abstract The studies on the structural formulae of smectites in the Larneta sediments indicate that they are rich in octahedral Fe, Mg and tetrahedral Al. Identical patterns of Mg, Fe and Al abundances in the octahedral and tetrahedral layers respectively, were also observed in the smectites of intertrappean sediments and weathered Deccan Basalts. The thermodynamic components and charge configurations of smectites in the Lameta, intertrappean and Deccan Basalt indicate that they fall within the compositional plane of smectite solid solution. The compositional commonality of smectite in the Lameta sediments with those in the intertrappeans and weathered Deccan Basalt suggests, Smectites in the Lameta sediments are derivatives of Deccan volcanic products. This implies the commencement of Deccan Volcanism during the Maastrichtian Lameta sedimentation or prior to it.

Palynostratigraphy of infra-trappean Jabalpur and Lameta Formations (Lower and Upper Cretaceous) in Madhya Pradesh, India

The Jabalpur and Lameta Formations comprise infra-trappean sedimentary sequences around Jabalpur, Madhya Pradesh, which represent the lower and upper parts of the Cretaceous System, respectively. A rich palynological assemblage consisting of 152 species belonging to 91 genera of different groups of plants has been recovered from these strata. The present paper deals with the palynological zonation of Jabalpur and Lameta sediments and their stratigraphy in relation to age and environment of deposition. Freshwater and marginal marine environments of deposition are concluded for the Jabalpur and Lameta Formations respectively on the basis of the composition of the palynomorph assemblages. The Jabalpur Formation is Early Cretaceous ( c. Berriasian-Barremian) in age, whereas the Lameta Formation was deposited during the Maastrichtian.

Palaeontological and sedimentological observations on nonmarine Lameta Formation (Upper Cretaceous) of Maharashtra, India: their palaeoecological and palaeoenvironmental significance

The Lameta Formation (Upper Cretaceous) is exposed in parts of central and western India as detached outcrops and covers an area of nearly 5000 km 2. It generally rests on Precambrian and “Gondwana” rocks and is invariably capped by Deccan Trap volcanic flows. In the Nand and Dongargaon areas of the Chandrapur and Nagpur districts of Maharashtra, the Lameta Formation covers more than 400 km 2, attains a thickness of 20 m and is richly fossiliferous. The palaeontological and sedimentological observations strongly indicate alluvial-limnic environment for the deposition of the Lameta sediments under semi-arid conditions. Different lithofacies representing channel, overbank, paludal and lacustrine subenvironments have been identified. The biota represents terrestrial, semiaquatic and aquatic communities and is represented by dinosaurs, fishes, crocodiles, chelonia, gastropods, ostracodes, charophytes, coniferales and angiosperms. The biota appears to be mainly controlled by the different lithofacies, thereby suggesting strong palaeoecological and taphonomical control over their occurrence. Records of mass death of clupeids have been observed in many layers within the lacustrine clays. A nesting site of sauropods has been found near Pavna along with evidence of site-fidelity. A clutch with small oblong-shaped eggs of avian-like affinity has been also unearthed from this nesting site. The Lameta sediments were deposited in a freshwater environment that provided the preferred ecological niche for large-scale breeding and nesting of sauropods.

Upper Cretaceous Dinosaur Eggs from New Localities of Gujarat, India

Abstract New occurrences of well-preserved dinosaur eggs have been found in the Lameta sediments near Dohad in Panchmahals district, Gujarat. The new localities lie 90 km east of the well-known Balasinor-Rahioli belt, which has the distinction of being one of the few dinosaur nesting sites in the world. The dinosaur eggs are spherical and have nodose ornamentation. Two types of egg shells have been distinguished on the basis of their microstructure. The egg shelIs have affinity towards sauropod types and are comparable to those of Kheda Type-B.

Palaeoenvironment and Stratigraphic Position of Green Sandstone (Lameta: Late Cretaceous) Jabalpur Area

Abstract Green Sandstone (Green Sand) of Lameta sediments, in Jabalpur area, makes a conspicuous basal lithounit of the succession. It is made up of clean sand without any shale intercalations, and ranges in grain size from medium to fine sand. Largescale cross-bedding in the form of large festoons is the most dominant structure, showing mostly a bipolar current pattern, where one direction is more prominent. The sandstone also exhibits branched Thalassinoides-type burrows. The Green Sandstone represents deposit of an estuarine channel with tidal influences exclusively by marine processes. The prominent southerly palaeocurrent direction at Chui Hill is interpreted as local ebb-current direction.