Calcareous Concretions Research Articles

A new anhanguerid pterosaur specimen from the Romualdo Formation, Araripe Basin (Lower Cretaceous, Northeastern Brazil)

ABSTRACT Pterosaurs, flying reptiles that lived during the Mesozoic era, were the first vertebrates to develop powered flight. Despite being patchy, the pterosaur fossil record extends worldwide, being quite diverse at the Araripe Basin, Brazil. The Romualdo Formation (Aptian-Albian), a Konservat Lagerstätten rich in calcareous concretions, has yielded several of these exceptionally well-preserved, three-dimensional fossils. MN 4727-V, the focus of the present study, consists exclusively of three-dimensionally preserved post-cranial axial and appendicular elements. The anatomy suggests that MN 4727-V is a pteranodontoid since it exhibits an enlarged, warped deltopectoral crest and a subtriangular distal articulation of the humerus. The phylogenetic analysis recovered MN 4727-V as an anhanguerid by the combination of the following characters: scapula substantially shorter than the coracoid (sca/co < 0.80), and posterior expansion of the sternal articulation of the coracoid. The presence of elliptical-shaped, dorsomedially inclined depressions on the dorsal surface of the prezygapophyses of the preserved cervicals has never been reported for any other anhanguerid, although they might not be diagnostic to MN 4727-V. The tail bears unique middle caudals that exhibit ventral projections, a character previously reported only for Anhanguera piscator. The wingspan of MN 4727-V, a juvenile individual, was estimated to be about 3.9 metres.

Exceptional In Situ Preservation of Chondrocranial Elements in a Coniacian Mosasaurid from Colombia

The first record of well-preserved chondrocranial elements in mosasaurids is here described. These elements are preserved in situ in a Coniacian skull found in north-central Colombia, inside a calcareous concretion. Based on a 3D model generated from computed tomography scans, we identified elements of the nasal and orbitotemporal regions. Our descriptions show that in this specimen, the chondrocranium was reduced, more so than in most lacertilians (including their closest recent relatives, the varanids), but not as severely as in snakes or amphisbaenians (which have an extremely reduced chondrocranium and limbs). The new evidence suggests that the reduction in the chondrocranium in mosasaurids could be related to modification of their limbs when adapting to aquatic environments, but also that in mosasaurids, the olfactory tract was reduced, and the optic muscle insertions occurred mainly in the interorbital septum. The exceptional preservation of the chondrocranial elements in the specimen is facilitated by a gray mineralization covering them. XRD analysis and thin section observations indicated that this mineralization is composed of microcrystalline quartz and calcite. We infer that this material was produced by a partial silicification process promoted by lower pH microenvironments associated with bacterial breakdown of non-biomineralized tissues during early diagenesis.

A marine incursion during the onset of T-OAE in Sichuan Basin, China: Evidence from green clay minerals and carbonate concretions

A high-amplitude global sea level rose rapidly during the early Toarcian (Early Jurassic), making the transgression deposits potential stratigraphic correlation markers of marine and terrestrial successions. Green clay minerals (i.e., glauconite and chamosite), carbonate concretions, and geochemical database associated with the early Toarcian global transgression are archived in the Lower Jurassic Da'anzhai Member (the Early Toarcian age) in the Sichuan Basin of China, a mega lake along the Tethys Ocean. The fine-grained glauconites with high Al and low Si contents suggested that they were transported from offshore to the lake by marine incursion and were oxidized during the transport processes. The green authigenic chamosite cement and redeposited chamosite grains with high Mg/Fe and low Al/Si ratios were diagenetically transformed from berthierine formed in the brackish water caused by marine incursion. The chemically impure siderite concretions with low 87Sr/86Sr ratios and high δ13C values suggested that the lake water and sediment pore waters were mixed with seawater. Coeval calcareous concretions have low 87Sr/86Sr ratios and high δ13C values, indicating the mixing of lake water with seawater. Combining the stratigraphic low 87Sr/86Sr values, we suggested that there was a marine incursion into the Sichuan Basin. According to the organic carbon isotopic stratigraphy correlation, the marine incursion occurred during the onset of T-OAE. The rapid and high-amplitude global sea-level rise may have caused this marine incursion.

Paleoproterozoic Rocks of the Belcher Islands, Nunavut: A Review of Their Remarkable Geology and Relevance to Inuit-led Conservation Efforts

The Paleoproterozoic Belcher Group (ca. 2.0 to 1.83 Ga) occurs on the remote Belcher Islands of Hudson Bay in Nunavut, Canada. It includes nearly nine kilometres of well-preserved siliciclastic and carbonate sedimentary rocks, deposited initially in a marginal to shallow marine setting representing one of the first true continental shelf environments on the proto-Canadian Shield. A wide variety of depositional facies exists within the Belcher Group, and it is particularly well known for its spectacular stromatolites in dolostone. In addition to these macroscopic features, two of its formations (Kasegalik and McLeary) contain intact microfossils of Eoentophysalis belcherensis, the oldest known occurrence of cyanobacteria in the geological record. The uppermost part of the Belcher Group contains sedimentary rocks of very different character that represent a younger foreland basin that developed in response to accretionary and collisional processes of the Trans-Hudson orogen. These younger formations (Omarolluk and Loaf) consist of a thick sequence of turbidites, overlain by arkose and other immature clastic sedimentary rocks. A defining characteristic of the Omarolluk Formation is the presence of calcareous concretions. The Omarolluk Formation shares attributes with “omars”, which are glacially transported clasts that occur both locally and further afield throughout parts of Canada and the northern United States and have helped characterize Pleistocene ice-flow trends across the continent. The Belcher Group also includes two formations dominated by spectacular mafic volcanic rocks. The earlier episode, represented by the Eskimo Formation, reflects eruption of largely subaerial volcanic flows interpreted to represent flood basalt associated with the rifting of Archean basement during the establishment of the continental shelf. A later volcanic episode (the Flaherty Formation) is dominated by submarine pillowed basalt flows and has been assigned to varied tectonic settings, including volcanic arcs related to subduction and oceanic plateaus related to mantle plume activity and renewed rifting along the continental margin. This later volcanism marks the transition from shelf to foreland basin. Mafic sills and related intrusions (Haig intrusions) occur in the middle and lower part of the Belcher Group. Thermal and chemical interactions between mafic magma and calcareous shale generated unusual rocks that are well known in Nunavut as high-quality artisanal carving stone. The Belcher Group also contains Superior-type iron formations that have attracted past exploration interest. The Belcher Group is a unique geological entity defined by its wide variety of rock types, its superb exposures, and its potential to illustrate many important geological processes in a formative time in Earth’s history. It is also a unique microfossil paleontological resource, and its deposition brackets a crucial and much-debated interval of Precambrian atmospheric and oceanic evolution. It represents an important scientific resource in the context of understanding such changes. This general review paper highlights its most important features, discusses its potential for future research and contributes to wider discussions about its possible future role as a protected area within Nunavut.

Desmoinesian (middle Pennsylvanian) radiolarians from the Excello Shale of Kansas, USA

Desmoinesian (Middle Pennsylvanian) radiolarians are described from carbonate concretions found in the black phosphatic facies in strata of the Excello Shale Member of the Fort Scott Limestone (Marmaton Group) in southeastern Kansas (K69 section), USA. Ten new species of radiolarians are described: Albaillella kansaensis, Holdsworthella trifurca, Pseudoalbaillella deformata, Entactinia jayhawkensis, E. heckeli, E. boardmani, Apophysiacus martiali, Moskovistella insolita, Palacantholithus umbrelliformis, and Ormistonella perrara. The Kansas radiolarian assemblage is different from the assemblage described from the Excello Shale of Iowa in the preservation and taxonomic composition. The radiolarians are preserved as pyritized internal molds or regular tests replaced by pyrite, and unidentifiable organic material. The domination of entactinarians and albaillellarians in the Kansas assemblage and their poor to excellent preservation indicate the formation of early diagenetic calcareous concretions in anoxic conditions. The appearance of the spicular radiolarian genus Palacantholithus indicates an influx of relatively cold water connected with upwelling. The Kansas location was much farther offshore (450 km basinward) compared to the Iowa localities suggesting a difference in thermocline depth, affecting water temperature, oxygenation, and nutrients.

An Unusual Fossiliferous Site in the Romualdo Formation in the Socorro Basin (Northeast Brazil)

The Santana Group, from the base to the top, comprises the Barbalha, Crato, Ipubi, and Romualdo formations. Calcareous concretions from the Romualdo Formation are found in the Araripe Basin, but the geographic extension of this sequence has evidence in the Socorro Basin on the border of the state of Pernambuco; however, these areas outside of the Araripe Basin have rarely been investigated. The purpose of this research was to carry out a data survey of fossils collected in the Romualdo Formation from the Socorro/Santo Ignácio Basin area that were found in the northeastern portion of Ouricuri municipality in the state of Pernambuco; a new fossiliferous site, known as the Cara Branca site, is reported. Samples were collected from the surface and often in the off-season. This area is cleared by tractors for planting, either exposing fossils or moving some of the fossils. This disturbance reinforces the need for fossil rescues and excavations in this area, where weathering, agricultural machinery, and erosion can damage the fossil record. According to the initial paleontological sampling, the obtained taphonomic information pointed to rapid burial, and the degrees of disarticulation observed in some specimens indicated that disarticulation occurred through necrolysis.

Removal of Calcareous Concretions from Marine Archaeological Ceramics by Means of a Stimuli-Responsive Hydrogel

The presence of calcareous concretions on the surface of marine archaeological ceramics is a frequently observed phenomenon. It is necessary to remove these materials when the deposits obscure the feature of ceramics. Unfortunately, calcareous concretions provide distinctive documentation of the burning history of ceramics. The interaction of acid solution or detachment of the deposit layers in physical ways leads to the loss of archeological information. To prevent the loss of archeological information and to achieve precise and gentle concretion removal, responsive hydrogel cleaning systems have been developed. The hydrogels synthesized are composed of networks of poly(vinyl acetate)/sodium alginate that exhibit desirable water retention properties, are responsive to Ca2+ ions, and do not leave any residues after undergoing cleaning treatment. Four distinct compositions were selected. The study of water retention properties involved quantifying the weight changes. The composition was obtained from Fourier transform infrared spectra. The microstructure was obtained from scanning electron microscopy. The mechanical properties were obtained from rheological measurements. To demonstrate both the efficiency and working mechanism of the selected hydrogels, a representative study of mocked samples is presented first. After selecting the most appropriate hydrogel composite, a cleaning process was implemented on the marine archaeological ceramics. This article demonstrates the advantages of stimuli-responsive hydrogels in controlling the release of acid solution release, thereby surpassing the limitations of traditional cleaning methods.

Deciphering the Color Origin of Pink Conch Pearl Using Nondestructive Spectroscopies and DFT Calculations

Conch pearl is a calcareous concretion produced by the Queen conch mollusk and is of extremely high economic value. Its attractive pink color has remained a mystery for hundreds of years. This difficulty limits the development of cultivation and preservation technology of conch pearl. Due to its super-high value, it is generally impossible to use destructive chemical analysis methods. Here, various nondestructive spectroscopic analysis methods and theoretical calculations were used to reveal the color origin of pink conch pearl. The experimental Raman and UV-Vis spectroscopies were used to characterize the color and pigments. We further discuss the pigments in conch pearl by comparing the Raman spectral characteristics and pigments of the red coral. Based on the characteristics of the experimental spectra, we speculate that the carotenoids color the conch pearl. The theoretical Raman and UV-Vis spectra of all-trans polyene and carotenoids were simulated using DFT calculations. According to the results, we proposed that the pigments in pink conch pearl are polyenes containing 11 shortened C–C bonds with multiplicities &gt; 1.5, which may be demethylated carotenoids.

The Study of the Effects of Supplementary Cementitious Materials (SCMs) on Concrete Compressive Strength at High Temperatures Using Artificial Neural Network Model

In this study, an artificial neural network (ANN) model was developed to predict the compressive strength of concrete containing supplementary cementitious materials (SCMs) at high temperatures. For this purpose, 500 experimental results were collected from the available literature. The effective parameters in the model are the volumes of coarse and fine aggregates, water, cement, coarse-aggregate type, percentage SCMs as the cement replacement, temperature levels, and test methods. The proposed ANN model was developed at a correlation coefficient of 0.966. A parametric study was conducted to evaluate the impact of the combined effects of input parameters (aggregate types and SCM content) on the relative compressive strength of concrete at high temperatures. It was shown that siliceous aggregate has a better performance by producing stronger bonds with cement paste than calcareous aggregates. The optimum SCM contents depend on the aggregate types. The optimum silica fume (SF) content for concrete with a water-to-binder ratio of 0.6 subjected to high temperatures is 8% and 3% for siliceous and calcareous concrete, respectively. The analysis of the ANN model has provided a conclusive understanding of the concrete behaviour at high temperatures.

Large ammonoid shellbed and huge calcareous concretion bed in shallow-marine fine sandstone of the lower Coniacian Ashizawa Formation, Futaba Group, Northeast Japan

いわき市アンモナイトセンターの双葉層群足沢層大久川部層（コニアシアン下部）のアンモナイト（主に径40-60 cmのMesopuzosia yubarensis）密集層と直下にある炭酸塩コンクリーション濃集層の，堆積相・産状観察と地球化学分析から形成過程を考察した．M. yubarensisは，沖合いの生息場から死後浮遊で沿岸に達した軟体部の失われた殻が，ストーム波浪で住房部が破壊され，分級・集積・運搬され，下部外浜沖合い側で癒着HCS極細粒砂層のハンモックマウンドに沿って急速に埋積した．炭酸塩コンクリーションは，多様なサイズ（径15-194 cm）の長-扁球形で，密集しながらも比較的一様に分布する．コンクリーションの形成は，ストーム波浪で運搬された有機物と底質中のベントス遺骸の分解に伴って堆積物の浅所で始まり，その後，埋没に伴い堆積物深所におけるメタン生成帯での有機物分解が生じるまで継続した．

Estudios geológicos, biológicos y físico-químicos para la conservación y restauración de la fuente de la plaza Weyler (Santa Cruz de Tenerife, España)

This work presents the set of preliminary studies for the conservation and restoration of the fountain in plaza Weyler (Santa Cruz de Tenerife). The working methodology is interdisciplinary and aims to identify and characterize the construction materials, along with the products generated in the alteration processes, to determine the mechanisms and causes of deterioration. Two marbles of different origins belonging to two construction phases of the aforementioned square, a traditional mortar of limestone and sand as mortar, calcareous concretions resulting from filtrations and biological colonization by microalgae have been identified. A method of non-invasive analysis has been used to determine the extent of certain pathologies. In this way, it will be possible to define a specific proposal of action to deal with the pathologies affecting this cultural asset.

Spark plasma sintering using calcareous waste concrete powder

• Spark plasma sintering (SPS) of milled calcareous waste concrete was investigated. • Waste mortar powder (WMP) and waste coarse aggregate powder (WCAP) were prepared. • The flexural strength of the WMP and WCAP was higher than the ISO 13,006 standard. • Spurrite, gehlenite, wollastonite, larnite, and magnetite were synthesized by SPS. In this study, spark plasma sintering (SPS) was performed using calcareous waste concrete powder. In particular, we examined the sintering temperature for SPS. This improved the flexural strength and flexural modulus. Two types of calcareous waste concrete powders were prepared: waste mortar powder (WMP) and waste coarse aggregate powder (WCAP). The characteristics of the sintered bodies were evaluated using a three-point flexural test and powder X-ray diffraction (XRD). As the main crystalline component of the raw powder, WMP included calcite and quartz, and WCAP included calcite and hematite. Regarding the flexural strength of the sintered body, WMP had 52.6 MPa at a sintering temperature of 900 °C, and WCAP had 42.4 MPa at a sintering temperature of 850 °C. These values are higher than the value of 35 MPa of ISO 13,006 standard, which prescribes porcelain stoneware tiles. XRD analysis reveals the synthesis of spurrite, gehlenite, wollastonite, and larnite in WMP, and in WCAP, spurrite and magnetite are confirmed. The synthesis of these chemical compounds is attributed to the decarbonation reaction of calcite at 760 °C. Therefore, calcareous concrete can be used as a raw material for construction ceramics when applied to SPS.

The paleohistology of †Araripichthys castilhoi from the Lower Cretaceous of Araripe Basin, Northeastern Brazil: a typical case of basal teleost

ABSTRACT †Araripichthys castilhoi belongs to the paleo-ichthyofauna from the Aptian calcareous concretions of Romualdo Member, Santana Formation, Araripe Basin, northeast Brazil. It was originally placed within Beryciformes (Acanthomorphata) by a combination of plesiomorphic and apomorphic characters. Later, an anatomical review of †Araripichthys demonstrated the presence of several primitive characters (cf. presence of fin spines, orbitosphenoid, two supramaxillae, seven hypurals, autogenous hypurals 1 and 2, second ural centrum and first uroneural not fused, and cycloid scales) and aligned it with Clupeocephala. †Araripichthys was also considered closely related to †Acanthichthys (primitive Acanthomorphata), basically by the body shape resemblance. Other included †Araripichthys in †Protobramoidei (basal Clupeocephala) based on the absence of pelvic fins, presence of stout neural spines and scales partially covering the dorsal fin. The odd taxonomic history of †Araripichthys is directly related to its scarce number of available well-preserved specimens and concurrently its absence in a comprehensive phylogenetic analysis. Here we present a paleohistological study, an efficient tool to precise the taxonomic position of fossil fishes, especially in cases like that of †Araripichthys. Its paleohistology presents pseudolamellar bony tissues with stellate lacunae, filled by osteocytes with ramified cytoplasmic extensions. The star-shaped osteocytes of †Araripichthys are clearly characteristic of basal teleosts. Conversely, in the scarce Acanthopterygii taxa with cellular bone the osteocytes morphology is clearly distinct since their canaliculi are not regularly localized around these cells. The currently accepted synapomorphies for Elopomorpha, Clupeocephala, Acanthopterygii, and the already known anatomical data for †Araripichthys together with its paleohistology, corroborate its incertae sedis position within basal Teleostei.

Concrete/Glass Construction and Demolition Waste (CDW) Synergies in Ternary Eco-Cement-Paste Mineralogy.

The study described sought further understanding of the synergies in a mix of CDW pozzolans, containing (calcareous and siliceous) concrete and glass waste, used to prepare ternary eco-cement paste bearing 7% of the binary blend at concrete/glass ratios of 2:1 and 1:2. The mineralogical phases in the 2-day, 28-day, and 90-day cement matrices were identified and monitored using XRF, XRD-Rietveld, SEM-EDX, FT-IR, and NMR. The findings showed that changes in the reaction kinetics in the ternary blended pastes relative to OPC pastes depended on the nature of the recycled concrete and the glass content. Adding the binary mix bearing calcareous concrete (at a ratio of 2:1) favoured ettringite, portlandite, and amorphous phase formation, whilst the blends with siliceous concrete favoured C-S-H gel formation. Monocarboaluminate was detected in the 90-day siliceous concrete and glass pastes in amounts similar to those found in the reference OPC paste.

Marine deposits of the Chuy Formation (Late Pleistocene) and isostatic readjustments in the area of Laguna de Rocha (Uruguay)

The Chuy Formation is characterized by up to 135 m of an alternation of green pelites and fine to coarse sandstones with sparse invertebrate fossils. The marine deposits are interbedded with continental, loessic deposits of the Libertad Formation and overlain by the Dolores Formation, made up of mudstones with calcareous concretions. The results of the radiocarbon dating showed calibrated ages of 13.9±0.2, 41.5±1.9 and 50±3 ka BP on bioclasts of marine fossils at an elevation (above sea level, asl) of -2.8, -6.13 and -8 m respectively. Such ages and elevations are in disagreement with the sea-level evolution inferred for the Late Pleistocene. Two possible explanations are: (a) the ages represent minimum ages and deposition took place during the last interglacial at 115-130 ka (Marine Isotope Stage MIS 5e), or (b) they represent depositional ages but the area experimented large isostatic readjustments during and after the last glaciation. Several lines of evidence suggest a Late Pleistocene age for the upper Chuy Formation, including the d18O curve obtained from invertebrate shells, which shows large secular variations consistent with MIS 1 to 7. The proposed scenario envisages significant subsidence between 50-20 ka due to the far-field effects of glacial load in the Andes/Patagonia. At 20 ka the eustatic regression outpaced subsidence, leading to continentalization of the Laguna de Rocha area. Marine conditions returned at 15 ka and into the Holocene, except for continental deposits (Dolores Formation) at ca. 11-10 ka (Younger Dryas). An uplift of 115 m took place between 15 and 9 ka in the area, which is interpreted as post-glacial rebound. In the Holocene, moderate subsidence was further recorded. A regional trend is observed, with uplift of marine deposits increasing towards the W-SW, which is consistent with an explanation as post-glacial isostatic rebound.

Impact of calcareous concretions on soil shrinkage of a Vertisol and their relation model development

Shajiang black soil (Vertisol) has a high shrinkage capacity and contains many calcareous concretions (CC). We assume the volume of CC to be rigid during wetting and drying cycles. Thus, the soil containing CC may have different shrinkage behavior from that of fine soils (without CC). We aimed to quantify the effects of CC content and size on soil shrinkage behavior, as well as to develop a model to characterize the relationship among the void ratio (e), moisture ratio (υ), and solid volume of CC (Csv) in Shajiang black soil. Four different sizes (2–5, 5–10, 10–20 and, 20–30 mm) of the CC at a rate of 10% on mass, and four different contents (0, 5%, 10%, and 20% on mass) of 5–10 mm CCs were mixed into the fine soils to prepare the CC-soil mixtures. Our results showed that the increasing CC content significantly reduced the saturated void ratio (es), coefficient of linear extensibility (COLE), and shrinkage index of all pores except the medium pores (P < 0.05), but the CC size did not. The shrinkage curves of the CC–soil mixtures were proportional to that of the fine soil, which was modified by the portion of CC volume in the CC–soil mixtures. We proposed a new numerical equation based on Peng and Horn shrinkage model (2005) to illustrate the relationship among e– υ –Csv. The shrinkage curve of the CC–soil mixture was predicted well (R2 = 0.95–0.98) by the new model based on that of fine soil and the CC volume modification. However, the proposed model underestimated the volume change for the dry side of the shrinkage curve, in which the swelling and shrinkage of fine soil matrix among CCs were partially concealed. Our work demonstrates that the CC in the Shajiang black soil does not change soil shrinkage behavior except the modification of void ratio, and thus its shrinkage curve can be estimated from that of the non-CC soil. It can be concluded that this study provides a useful model for estimating the shrinkage behavior of soils containing rigid coarse inclusions.

Synthesis of zeolites from calcareous waste concrete powder

In this study, zeolites were synthesized from calcareous waste concrete powder (WCP) using a hydrothermal synthesis method. Effective utilization methods of waste concrete are required worldwide for prolonging the final dumping sites’ lifetime and for promoting a society that recycles. Calcareous concrete, which includes many calcium components, has been widely used. The WCP includes mainly calcite (at 66.9%) and quartz. First, we applied hydrothermal synthesis to raw WCP. However, X-ray diffraction analysis (XRD) revealed no zeolite synthesis. Next, we used the same approach on WCP-HCl (WCP with the calcium component removed by HCl treatment). For WCP-HCl, the synthesis of analcime-type zeolites was confirmed based on XRD and simple absorption tests, in which the WCP-HCl color changed from gray to blue upon its absorption of methylene blue. Finally, to determine the analcime synthesis requirements, we experimentally varied the synthesis. Analcime synthesis was observed at temperatures above 433 K after at least 12 h of heating and for NaOH solution concentrations above 2 mol/L.

Compressive Behavior of Oil Shale with Calcareous Concretion: Parametric Study

The non-uniformly distributed calcareous concretion among the oil shale in the Junggar basin of China has led to the difficulty in achieving the slope stability. This paper presents the numerical simulation of the behavior of oil shale with calcareous concretion via the Particle Flow Code (PFC2D) program based on the trial experimental test results. The critical parameters investigated in this research covered the size, distribution, strength, and number of the calcareous concretion. The following conclusions can be drawn based on the discussions and analysis: (1) the hard concretion always results in the high compressive strength of the specimen compared with that without concretion; (2) when the radius of the concretion size raised from 2.5 mm to 20 mm, the peak strength of tested specimens is approximately 50 MPa, whereas, the specimen with large concretion is much more ductile under compression; (3) the compressive behavior of tested specimens is similar even when the position of the concretion is variable; and (4) different from the specimens with only one concretion, these specimens contained two concretions featured with the double “X” failure mode. Meanwhile, the peak strength of the specimens with two hard concretions is about 2.5 times that of its counterparts with two soft concretions. The numerical simulation results are meaningful in guiding the design and analysis of the oil shale slope with the concretion.

Epistaxis Secondary to Rhinolith: A Forgotten and Scarce Entity

Rhinolith is a calcareous concretion resulting from mineralization and encrustation of an endogenous or exogenous nidus in the nose. This rare clinical entity could be the result of a previous introduction of a foreign body into the nasal cavity. Rhinolith is rarely seen by the clinical practitioner. We report a case of rhinolith in a young healthy lady who presented with epistaxis and highlight the clinical presentation and management of this case. The history of foreign body insertion may be overlooked in such cases. Presence of grittiness on endoscopic probing aid in establishing the diagnosis. Early referral from primary care centre to ENT can avoid misdiagnosis and further complications as removal of the rhinolith is the ultimate treatment.

Characteristic and paleoenvironment significance of microbially induced sedimentary structures (MISS) in terrestrial facies across P-T boundary in Western Henan Province, North China

AbstractWe report varied microbially induced sedimentary structures (MISS), and other sedimentary surface textures, from the Induan (Early Triassic) Sunjiagou Formation and Liujiagou Formation in the Xingyang, Dengfeng, Jiyuan and Yiyang areas, western Henan Province, North China. Microanalysis shows that these MISS are characterized by a U-shaped structure, thin clayey laminae, and discontinuous mica sheet that are arranged parallel to the bedding plane, as well as directionally oriented quartz grains floating in lamina, which are indicative of a biogenic origin. The MISS of the studied area were probably affected by four main factors, including the end-Permian mass extinction, the megamonsoon, the adapted sedimentary environment, and the sediment supply, and they possess significant stratigraphic correlation. Abundant microbial-related sedimentary structures from the study area indicate that continental ecosystems were severely devastated in the aftermath of the Permian-Triassic biocrisis. These sedimentary structure assemblages, including MISS, red beds, conglomerate layers, and calcareous concretions in the western Henan Province, show a specific, post-extinction continental ecosystem that was characterized by microflora dominance, monotonous and rare fossils, extreme hot climate, soil ecosystem devastation, and poor vegetation.