Facies Analysis Research Papers - Academia.edu (original) (raw)

2025

Cooper, M. R. 2002. Palaeolophid and liostreine oysters (Bivalvia: Ostreidae) from the Cretaceous of southeast Africa, with comments on oyster biostratigraphy and biofacies. Durban Mus. Novit. 27: 28-60. The palaeolophid and liostreine oysters are described, as a group, from the Cretaceous deposits of southeast Africa for the first time. The first to appear, in the Late Aptian (martinioides Zone), is Gyrostrea besairiei (Collignon), a species which becomes very abundant in offshore deposits of the lower Upper Albian (cristatum Zone). In the shallow-water nearshore deposits at the base of the Mzinene Formation (upper Lower Albian) it is joined by thick-shelled Rastellum allobrogensis (Pictet and Roux); R. cf. ricordeanum (d=Orbigny) is known by a single fragment from the low Upper Albian (cristatum Zone), and R. deshayesi (Fischer de Waldheim) occurs only in Santonian-Lower Campanian deposits of the Mzamba Formation associated with Curvostrea tevesthensis (Coquand). Acutostrea incurva (Nilsson) first appears in the Late Coniacian as a rarity but is particularly abundant in the late Early Maastrichtian (neubergicus Zone) where it is joined by equally-abundant Agerostrea mesenterica africana subsp. nov. Oysters are shown to have biostratigraphic significance, at least within the Cretaceous of the South Mozambique-Zululand coastal basin; they also have value as indicators of water-depth, and perhaps salinity, and six oyster biofacies are proposed.

2025, Proceedings of the Geologists' Association

This paper investigates thylacocephalan (?Crustacea) carapaces from the lower Famennian of the Holy Cross Mountains, Poland in order to check whether predation-related activities has influenced the mode of carapace preservation. Analysis of 225 specimens reveals that 71% of carapaces consist of complete/ nearly complete specimens, and those that are incomplete have experienced purely taphonomic processes. The remaining 29% of specimens, are damaged and fragmented carapaces, the preservation patterns of which point to biological modifications due to predation. These damaged carapaces range from those that have some portions missing, to those totally fragmented into small pieces scattered on bedding planes. The damaged specimens lacking some portions of the carapace are similar to those described previously from the Frasnian of Australia, where they are interpreted to evidence fish predation. The loosely scattered cuticle fragments are very similar to those reported from the Pennsylvanian of the USA that are interpreted as shark regurgitates. We interpret the damaged and fragmented thylacocephalans from Poland as evidence for fish predation, consistent with previous evidence from fragmented cuticle preserved within coprolites. However, as the majority of cuticle fragments occurring within coprolites in previous studies are difficult to distinguish, the simple calculation of predation intensity is much lower (13%) to that obtained in the present study (29%). Thus, analysis of thylacocephalan carapace preservation conducted here, may serve as a calibrating tool for the assessment of a general predation intensity in a given palaeoenvironment based solely on coprolite data.

2025, Lethaia

Fossil abundance data on foraminifer communities were collected in marginal marine sediments of the Pliocene Valdelsa succession, in Tuscany, Italy. This succession is organized in a hierarchy of elementary and composite depositional sequences. Multivariate techniques allowed to analyse the dataset and reconstruct gradients in species distributions. Species-level data available on modern environmental distributions were used to reconstruct Pliocene environmental gradients and to infer absolute palaeodepths and palaeosalinities. Estimates were then compared with the sequencestratigraphic interpretation to check for consistency. The high-resolution stratigraphic framework allowed us to test the stability of foraminifer communities against ecological variations related to high-frequency glacio-eustatic cycles. The results confirm that fossil distributions of foraminifer species can be used as a fine tool to detect environmental change and that multivariate techniques allow their interpretation in terms of absolute variations of controlling parameters. Salinity is the main contributor to the sum of depth-related factors that regulate foraminifer distributions in coastal facies. In the same setting, nutrient levels and the presence of a sea grass cover are responsible for secondary changes in shallow-water distributions. Below the wave base, however, depth-related parameters other than salinity explain the largest variations. This study indicates that foraminifer communities are random associations of species that respond individualistically to environmental change. ᮀ Community stability , foraminiferal palaeoecology , gradient analysis , sequence stratigraphy .

2025, Geobios

Lithofacies analysis of the upper part of the Pliocene succession of the Valdelsa basin (central Italy) unravelled a number of depositional environments, ranging from alluvial plain to coastal, to marine. Strata are arranged in a hierarchy of elementary and composite unconformitybounded units. A palaeoecological study of macro-(molluscs) and microfossils (pollen, dinocysts, foraminifera) allowed to finely reconstruct subenvironments within fine-grained terrestrial, coastal and marine deposits and thence to track the spatial and temporal change of physical conditions. The stacking pattern of sedimentary units highlights the lateral switching of onshore-offshore gradients and documents relative sea-level changes. These units are interpreted in a sequence stratigraphic framework. Elementary depositional sequences are arranged to form six composite depositional sequences, in turn encased within two major synthems. This hierarchy of unconformity-bounded sedimentary units suggests that sealevel variation has occurred at different time-frequencies. Glacio-eustasy and active tectonism are discussed as the main forcing factors regulating the different scales of sedimentary cyclicity.

2025, Palaeontology

Organised mineralised structures observed in large inoceramids (valves on a metre scale) from the Late Albian, Toolebuc Formation, Australia (Inoceramus sutherlandi McCoy, 1865), and the Santonian, Niobrara Formation, USA (Platyceramus sp.), were investigated using variable pressure scanning electron microscope (SEM) with energydispersive X-ray spectroscopy (EDX), X-ray microcomputed tomography (micro-CT) and X-ray diffraction (XRD) analyses. These indicate that the structures comprised a phosphate framework of aligned tubes and shallow troughs overlain perpendicularly by evenly spaced structures. In the Toolebuc Inoceramus, these are U-shaped cross-structures, whilst in the Niobrara Platyceramus, they comprise bundled fibre elements. Comparison with modern bivalves indicates that the observed phosphatised structures represent soft-tissue preservation of the gills, as suggested in earlier publications. The tubes and troughs are remnants of a filamental support framework comprising ordinary and primary filaments, whilst the U-shaped cross-structures (I. sutherlandi) and fibrous bands (Platyceramus) represent preserved longitudinal gill musculature. Internal perforate and strand-like fabric observed on the internal surface of some Platyceramus tubular structures suggests that the framework comprised collagen. The presence of primary and ordinary filaments in numerous unusually large plicae, in at least two lamellae, indicates that the gill structures were heterorhabdic. Each plica has at least 40 ordinary filaments, an exceptional number when compared with the maximum of 20 present in modern heterorhabdic gills. The

2025, IEEE Transactions on Geoscience and Remote Sensing

Deep neural networks (DNNs) can learn accurately from large quantities of labeled input data, but often fail to do so when labelled data are scarce. DNNs sometimes fail to generalize ontest data sampled from different input distributions. Unsupervised Deep Domain Adaptation (DDA) techniques have been proven useful when no labels are available, and when distribution shifts are observed in the target domain (TD). In the present study, experiments are performed on seismic images of the F3 block 3D dataset from offshore Netherlands (source domain; SD) and Penobscot 3D survey data from Canada (target domain; TD). Three geological classes from SD and TD that have similar reflection patterns are considered. A deep neural network architecture named EarthAdaptNet (EAN) is proposed to semantically segment the seismic images when few classes have data scarcity, and we use a transposed residual unit to replace the traditional dilated convolution in the decoder block. The EAN achieved a pixel-level accuracy >84% and an accuracy of ~70% for the minority classes, showing improved performance compared to existing architectures. In addition, we introduce the CORAL (Correlation Alignment) method to the EAN to create an unsupervised deep domain adaptation network (EAN-DDA) for the classification of seismic reflections from F3 and Penobscot, to demonstrate possible approaches when labelled data are unavailable. Maximum class accuracy achieved was ~99% for class 2 of Penobscot, with an overall accuracy>50%. Taken together, the EAN-DDA has the potential to classify target domain seismic facies classes with high accuracy.

2025

This study was carried out to better understand the geology and depositional environments of rock units in the Ede-Oballa - Orba axis of southeastern Nigeria. The integration of outcrop data, facies and sedimentological analyses aided the interpretation of the depositional setting of the sediment packages. Geologic mapping showed that the area is underlain by the Ajali Formation and Nsukka Formation of the Anambra Basin. Three outcropping lithologies were identified namely: sandstone, siltstone and mudstone. Facies analysis revealed eight (8) lithofacies namely: Conglomeritic Sandstone (CS) facies, Structureless sandstone (Ss) facies, Heterolith (H) facies, Siltstone (Si) facies, Mudstone (Fm) facies, Interbedded Sandstone and Mudstone (SM) facies, Cross-bedded sandstone (Cbs) facies and Ferruginized Sandstone (IS) facies. These lithofacies were further grouped into four facies associations; FA1 - prodelta deposits, FA2 - delta front deposits, FA3 - distributary channel-fill deposits and FA4 - fluvial channel deposits. Result from sieve analysis data indicates that the sands are generally medium to coarse-grained, but dominantly medium-grained, poorly to moderately sorted, due to fluctuations in energy of depositional agent, albeit with dominance of high energy. Bivariate discriminant plots of Mean vs Sorting and Sorting vs Skewness indicate fluvial – shallow marine environments. In addition, paleocurrent analysis showed unimodal, low variance pattern and vector strength of (0.94) suggesting fluvial environment of deposition. Overall, the rock units of the study area were deposited generally within the environments that span from continental through marginal marine setting.

2025, Journal of Maps

Based on mapping of laterally traceable stratigraphic discontinuities, we propose a highresolution allostratigraphic scheme for one of the world's foremost fossil marine vertebrate Lagerstätten: the lower Miocene strata of the Chilcatay Formation exposed along the Ica River near Zamaca, southern Peru. Measured sections combined with 1:10,000 scale mapping of a 24 km 2 area provide an overview of the stratal architecture, as well as a general facies framework and interpretation of the various depositional settings. As a whole, the Chilcatay alloformation is bounded by the CE0.1 unconformity at the base and the PE0.0 unconformity at the top. An internal Chilcatay surface, termed CE0.2, splits the alloformation into two distinct allomembers (Ct1 and Ct2). The Ct1 allomember comprises three facies associations recording deposition in shoreface, offshore, and subaqueous delta settings. The Ct2 allomember comprises two facies associations, recording deposition in shoreface and offshore settings. Using these data, we place the rich marine vertebrate assemblage in a precise spatial and stratigraphic framework. The well-diversified vertebrate assemblage is dominated by cetaceans (mostly odontocetes) and sharks (mostly lamniforms and carcharhiniforms); rays, bony fish, and turtles are also present. Taxonomic novelties include the first records of baleen whales, platanistids, and eurhinodelphinids from the Chilcatay Formation.

2025, Journal of African Earth Sciences

The Shiranish Formation represents one of the most important fractured reservoirs in northern Iraq. In this work, the petrophysical properties of the formation have been fully characterised using microscopy, core analysis, and well log analysis using conventional methods as well as new quantitative diagenetic approaches. During this work we have developed methods to quantify a petrophysical heterogeneity index (χ), reservoir quality indicator (RQI), and fracture effect index (FEI) for each of the stratigraphic units of the formation. The FEI was calculated by dividing the difference between the mean permeability of the wireline log data and the mean permeability of the unfractured core plug samples by the difference between the mean porosity of the wireline log data and the mean porosity of the unfractured core plug samples. This study shows that the Shiranish Formation has a fracturing pore system in all the characterised units, but it is particularly well developed in U.4, which shows the best reservoir quality (A and B). The new methods developed in this study can be applied to any carbonate formation to provide a trustworthy way to obtain a reservoir quality indicator linked to the petrophysical heterogeneity of the studied formation.

2025

Alberta Geological Survey completed field programs in June 2007 and October 2008 near Cardston, Taber and Fort McLeod. We described outcrops of Upper Cretaceous and Tertiary formations in the field, took radioactivity measurements onsite, and collected 122 samples for determination of multiple elements. Representative thin sections were prepared and detailed petrographic descriptions, including point counts, were made. We conducted a radiometric survey along the St. Mary, Waterton and Oldman rivers. The most notable result of the 2007 and 2008 field programs was the discovery of a new radioactive occurrence, consisting of anomalous uranium content (158 ppm) in the siltstones of the Willow Creek Formation along the Oldman River. An automated evaluation of tens of thousands of digital logs from oil and gas wells, and subsequent detailed analysis of 1800 well logs, outlined areas for future assessment. We selected anomalous gammaray intervals in the upper 550 m for determination of rock type and formation. Eighty-two per cent of the high-gamma intervals occur within shaly units with a high organic content (e.g., Base of Fish Scales and Second White Specks formations). Clusters of wells with high gamma readings in sandstone occur in NTS areas 82O, 83G, 84D and 83O. In the Claresholm area, multiple wells with high gamma readings in sandstones of the Willow Creek and St. Mary River formations occur within the upper 500 m. Testing drill cuttings from oil and gas wells that cover radioactive intervals was unable to confirm the source rocks for the radioactive anomalies but provided insight into the rock types of these intervals. We collected 109 and 18 rock samples during 2007 and 2008, respectively. All samples were analyzed using inductively coupled plasma (ICP-OES) following HNO 3 /HCl partial digestion and HF/HNO 3 /HClO 4 total digestion. Uranium was also analyzed by the more sensitive fluorimetry method.

2025, Lunar and Planetary Science Conference

2025, The University of Hong Kong (Pokfulam, Hong Kong)

A high-level coastal deposition feature at the southern tip of Ap Lei Chau, Hong Kong Island, is studied in this report to understand its paleo-depositional environment. Previous systematic surveys for similar deposits in Hong Kong were conducted between 1986 and 1996 during the production of fifteen 1:20,000 scale geological maps, and subsequently reviewed wholistically by Wong & Shaw in 2009. Studies of specific sites were conducted by different parties as well such as at Po Chue Tam, Lantau Island in 2000 and 2003. Possible formation processes for these features such as eustatic changes in sea level, local variations in sea level, extreme wave events, high waves and wind action, winnowing, and neotectonic activity were proposed by the Wong & Shaw (2009) study. In this study, literature reviews are carried out to understand the existing models for Quaternary sea level changes in Hong Kong, methods for quantifying clast size, sphericity and roundness, findings from previous studies on similar site in Hong Kong, and the ground model of the site. Field studies comprising joint set survey, vertical photographic scan line assessment of 198 clasts and general observations such as grain sizes and shape distribution, clasts preferred orientations, are conducted and discussed to deduce the possible mode of deposition, potential sources, and likely age of the site. It is concluded in this study that the site consists of five layers exhibiting fluvial depositional processes at the lower three layers and colluvial processes for the upper two layers. A joint set bounded wave-cut notch was formed after the uplifting of the area and favors the deposition of coarse grain material on a beachor tombolo-like environment. Subsequent debris slide and collapse of the wavecut notch formed the colluvial layers of the site.

2025

Synthesis of sedimentologic, paleocurrent, and organic geochemistry data of the Lower Permian Ga'ara Formation from the Western Desert, western Iraq, shows good hydrocarbon potentiality and deposition by high sinuosity and mixed-load channels, likely by a meandering river system. The Ga'ara Formation includes kaolinitic mudstone beds of various colors and channelized quartzitic sandstone beds. Based on the lithofacies identification, five lithofacies associations have been recognized: channel-floor, point-bar, abandoned channel plug, crevasse splay, and interchannel flood basin. In addition, the paleocurrent analysis and sandstone percentage map indicate a variation of the paleoflow spatially and temporally with a general direction range between NE and Sw, and the depositional environment has been interpreted as a meandering river system. To unravel the hydrocarbon potentiality of the Ga'ara Formation deposits, Pyrolysis and TOC% analyses were conducted on selected samples. The studies indicated that the Ga'ara Formation in western Iraq could be a moderate to excellent rock source. The PCI agrees with TOC content, suggesting that the generation potentiality of the mudstones as a source rock is poor and poor to excellent. All the analyzed samples show that their hydrocarbons are indigenous. The Ga'ara mudstones of the Nijili and West Tayyarah have very good generative potential, whereas the Ubairan samples have excellent generation potentiality. The Nijili and Ubairan samples are at an early stage of oil generation, i.e., immature. In contrast, the Tayyarah sample represents a postmature phase at the end of oil generation. Collectively, these new data on spatial distribution, geologic characters, and organic geochemistry propose that the Ga'ara Formation in western Iraq could be a valuable economic asset with good hydrocarbon potentiality .

2025

2025, Mayssa N. Shehab

Lost circulation, the loss of drilling fluid into holes or
fractures throughout the geological formations being drilled,
is the most expensive problem encountered in drilling
operations for oil and gas wells. It is known that when there is
a loss of circulation during the drilling process, the operation
activities are delayed or stopped for curing or treatment,
resulting in extra time known as non-productive time (NPT).
The NPT issues during the drilling operations are the most
important priorities for planning any drilling program.
Therefore, the lost circulation is one of the main problems
which can control the NPT. To mitigate the lost circulation
problems, an integrated investigation is necessarily needed for
the main parameters which enhance/downgrade the rate of
lost circulation.
Drilling through the Dammam and Hartha formation is
typically accompanied with substantial nonproductive time
due to severe and often entire drilling fluid losses. The
majority of the curing this problem require time for
preparation, placement or setting. In this research, a field
study was carried out to investigate the effect of 6 drilling
parameters on the rate of the lost circulation. The investigated
parameters are the rate of penetration, weight on bit, stand
pipe pressure, mud weight, flow rate, and the equivalent
circulation density. Furthermore, the effect of lithology type
on the lost circulation rate was clearly determined and
correlated. In addition, a graphical representation of bit depth
vs the real drilling time/date was constructed to compare the
lossy wells vs non-lossy wells named frithogram. This study
was based on field data for 350 wells drilled in Rumaila
Oilfield, southern Iraq. The results of this study showed that if
these six operating parameters are standard and controlled, the
significance of lost circulation problems could be reduced.
However, the main factors which are responsible for the lost
circulation problems are lithology types, facies and/or
diagenesis process, which mainly distinguish the carbonate
formations.

2025, Mayssa N. Shehab

The Mishrif Formation was studied in seven wells that were distributed in the Nasiriya Oil-
field, southern Iraq, well logs were obtained for these wells and included: Gamma ray,
Neutron, Density and Resistivity log. The Nasiriya Oil field is located at the unstable platform
Mesopotamian zone. The Mishrif Formation was divided into two rock units, the upper MA
and lower MB, separated by insulating shale rocks based on the gamma ray log. Furthemore,
the lower rock unit was also divided into two reservoir units MB1 and MB2. The petrophysical
properties of the formation were studied using various logs and through realationships
between the logs. The petrophysical study of the water and hydrocarbon saturations showed
that the formation contains varying proportions and quantities of water and hydrocarbons that
can be produced. The research also included a statistical study and calculation of reservoir
heterogeneity using two methods: first using the Dykstra-Parsons Coefficient, where the
results showed that is, the Lateral extension of the reservoir units of the study wells are
heterogeneous, and second using the Lorenz coefficient, where the results showed that wells
heterogeneous distribution, while Ns-9 and Ns-16 wells a homogeneous distribution.

2025, Mayssa N. Shehab

One of the most useful logging tools for identifying losses and fractures is Formation Micro
Imager. Drilling through the Dammam Formation is typically associated with substantial
nonproductive time due to severe and often entire drilling fluid losses. The majority of
remedy this problem require time for preparation, placement or setting. Combining between
conventional well log and FMI log associated with drilling data, a special study of the
shallow Dammam carbonate formation penetrate by wells is accomplished. For a better
understanding of the loss mechanism, Image log study was highlighted to imagine the loss
zones and as such adapt data to advance loss prevention or cure future scenario. Five images
and conventional logs available data associated with drilling operation documents were
applied to suggest best subsurface stratigraphic facies in order to knowledge sediment
environment of Dammam Formation. Five image log facies were identified as representing
the different environments within the different depths, large, fine vugs, carbonate layers,
laminate interrupt and laminate. The stratigraphy succession reveals shallowing upward
from deep water represented by laminate facies to more disturbed water signified by vuggy
large facies. There are six internal picks zone according to GR log sign D90 at the top of
Rus Formation, D80, D70, D65, D60, D50 and D40. It has been clear that nearly severe or
complete losses events limit intensively in D60 and D65 based on logs interpretation
analysis associated with drilling data.

2025, Revista del Museo Argentino de Ciencias Naturales

Stratigraphic and taphonomic analysis of Bonitasaura salgadoi Apesteguía (Sauropoda, Titanosauria) at «La Bonita» site (Upper Cretaceous, Rio Negro Province, Argentina). «La Bonita» is a fossiliferous locality close to the town of Cerro Policía, Río Negro Province, Argentina. At the quarry are exposed siliceous rocks belonging to the Bajo de la Carpa and Anacleto formations (Santonian-Campanian), separated by an unconformity from the Renteria Formation (Upper Pliocene-Pleistocene). The Bajo de la Carpa Formation is composed of sandstones, fine beds of conglomerates, alternate with pelites and wackes beds. The Anacleto Formation is composed of sandy to pelitic beds. The Renteria Formation is dominated by conglomerates with clasts that reach 15 cm in length, included in a sabullitic matrix. The facies analysis suggests a fluvial regime, with a subacuatic control with changes from mid to low energy. The lenticular-shaped sandy channels with crossed stratification point to an unidirectional flow in the transporting agent and bioclasts. The taphonomical analysis suggested that the dinosaur dies close to the river margins, being rapidly incorporated to the fluvial sediments that sepulted the specimen in successive events. The spatial distribution and bone relations suggest a very short transport from the source area, with a slight northward movement. The presence of two caudal vertebrae series with an opisthotonous articulation pattern, suggests that the animal was exposed long enough to permitt the rigor mortis and dissecation. The disarticulation degree also point to some amount of weathering of the skeleton before being sepulted. However, the exceptional periostium preservation in many cases suggests a very short subaerial exposure.

2025

Reefs are hotspots of diversity, modifying their surroundings and fostering numerous biotic interactions: in the fossil record, they preserve valuable paleoecologic and paleoenvironmental information. Early Cretaceous reefs are understudied; this paper analyzes the sclerobiont fauna of an Hauterivian patch-reef from the Neuquén Basin (Argentina) to interpret its life history and paleoenvironmental significance. Massive and ramose forms of paleoautoecologically homogeneous genera comprise this reef; corals bore zooxanthellae and presented features indicative of a tolerance for highsedimentary input. Sclerobionts were analyzed separately for ramose and massive corals. In addition, upper and lower surfaces of massive corales were also logged separately. The sclerobiont fauna comprised mainly thecideid brachiopods, oysters, serpulids, cyclostome bryozoans and calcareous sponges; in ramose corals only, microbial crusts are recorded and encrusted by sclerobionts. Massive corals presented lowered diversity indices and lacked microbial crusts. In both coral morphotypes, bioclaustrated sclerobionts were registered: in particular, serpulids established mutualistic relationships with the corals. Massive corals undersides hosted a much more abundant, sciaphyllous scleobiont fauna. This patch reef established in a mid-ramp setting under relatively high sedimentation rates; massive corals were buried more quickly than ramose forms. The microbialites on the latter indicate lowered sedimentation rates after the coral reef had already dwindled, likely due to nutrient enrichment, but with ramose corals mostly in life position. Thus, at Early Cretaceous mid-latitude settings, corals were adapted to suboptimal settings in settings with relatively high sedimentation, sustaining a moderately diverse and dynamic sclerobiont fauna composed of mostly heteretrophic organisms.

2025

The integration of sedimentary facies analysis, ichnology and benthic mollusc quantitative paleoecology allowed interpretation of factors that have controlled the deposition of the alluvial to marine succession outcropping in Northwestern Sicily (Southern Italy) at Altavilla Milicia, near Palermo (Imerese Basin). Two main marine units are recognised, labelled CNM and ALT, separated by an angular unconformity and formed by elementary depositional sequences (CNM1-4, ALT1-5). The succession was subdivided by means of calcareous nannoplankton biostratigraphy into upper Pliocene (Piacenzian: CNM1-4 and ALT1-4) and lower Pleistocene (Gelasian, ALT4-5), covering the onset of the Quaternary glaciation. The main asset of the succession is driven by tectonic compression and accommodation by transpressional faults, a regime that led to a change in the direction of fluvial sediment delivery, from axial (mid-Piacenzian: CNM), to transverse with respect to the basin elongation (upper Piacenzian-Gelasian: ALT). High-frequency eustatic changes drove the formation of elementary depositional sequences, the building blocks of CNM and ALT. During the late Piacenzian, a phase of gradual passage from the mid-Piacenzian warm period to the Quaternary glaciation, bioclastic production was still high, characterising the maximum flooding intervals of the two composite depositional sequences CNM and ALT. Mixed carbonate-siliciclastic lithosomes of both CNM and ALT show a good correlation with shallow marine shell-rich detrital carbonates of Northern and Southern Italy and with Mediterranean deep-water sapropel clusters, suggesting common climatic forcing. Some tropical species thought to disappear from the Mediterranean at around 3.0 Ma, including Pecten bosniasckii, Macrochlamys latissima, Spondylus crassicosta, Lucina orbicularis, Isognomon maxillatus, Crassatina concentrica, Gastrana lacunosa, Callista italica, Circomphalus foliaceolamellosus and Persististrombus coronatus, are present in the upper Piacenzian of Sicily (top of the MN16a Zone and the MN16b/17 Zone of calcareous nannofossil biostratigraphy). More data are needed to reconstruct the geographic dimension in the disappearance of the Mediterranean Pliocene macrobenthos with tropical affinities.

2025, Journal of Earth Science & Climatic Chang

The Eocene-Oligocene sand facies is well exposed around Osumenyi and Ukpor areas in the Anambra Basin of southeastern Nigeria. Outcrop sections were located, measured, described in detail and sampled so as to decipher the paleoenvironment of deposition, using an integration of sedimentary facies and grain size analyses. The sedimentary facies study suggests that the Eocene-Oligocene age in this area consist mainly of three facies association; sandstone, lignite and clay facies. The fine-grained sandstone sub-facies is indicative of shoreface, the medium grained sandstone sub-facies is indicative of estuarine, while the coarse-grained sandstone sub-facies suggests a fluvial environment. The lignite facies indicate a continental origin (swamp environment) while the clay facies are interpreted as fluvially intercepted shallow marine environment. Results of grain-size analysis for the Eocene-Oligocene age show that the sands are medium grained, moderately to poorly sorted, very negatively to positively skewed and very platykurtic to very leptokurtic. Bivariate plots of mean size against standard deviation and skewness against standard deviation support a fluvially dominated shallow marine environment with tidal crosscuts. Result of multivariate functions showed a fluvially intercepted shallow marine environment. This study is significant in providing evidence for the reservoir potentials and aquifer characteristics of the Eocene-Oligocene sand facies for petroleum accumulation and prolific water bearing units within the basin.

2025, Journal of Earth Science & Climatic Change

2025, Catena

The correct determination of sedimentation processes in caves is often complicated by the unique characteristics of cave environments and their relationship to surface soil. A study at Cuvieri Cave has allowed new insights into the dynamics and evolution of these types of sedimentary facies and their relation to the nearby landscape. The cave is located in the Lagoa Santa Karst, eastern Brazil, and contains fossiliferous deposits of Pleistocene-Holocene age at the base of three vertical pits near the cave entrance. Facies analysis was applied to sediments to understand sedimentation process, and sediments were described according to their morphology, grain-size, micromorphology, chemical composition, paleontological content and age. Results indicate that all deposits present a soil-like aspect and although they record several depositional conditions, sedimentary structures and textures are similar among different facies. As such, facies were defined by a combination of matrix color, degree of cementation and sedimentological characteristics. Additionally, abundance of fauna remains, their taxonomic composition (extant vs extinct), completeness, and degree of individuals' articulation was evaluated. Differences between facies were produced by two main factors: (i) change in source area and transport route (from the epikarst to doline colluviation and back to epikarst) and (ii) change in type of sediment cover injected, from doline fed soils, followed by talus debris and finally soils from modern epikarst. The change in both factors is related to the landscape evolution, mainly with the development and progressive enlargement and deepening of the nearby doline. Additionally, the change in the type of sediment cover injected could also be related to climatic evolution. The complex evolution of Cuvieri Cave sediments occurred over at least the last 300 kyr and is marked by periods in which entrance opening allowed the incorporation of vertebrate (both extinct and extant) remains into the sediment. Detailed multidisciplinary field and laboratory analyses are essential in unraveling the long history of sedimentation in caves, providing a framework in which multiple events of sediment input and erosion can be correctly interpreted and related to the evolution of the landscape.

2025

A este último agradecemos também pelas inúmeras contribuições em termos de cartografia geológica e geoprocessamento. Aos geólogos Inácio de Medeiros Delgado e Augusto Pedreira, da DIGEOB, agradecemos pela revisão do Mapa Geológico e da versão final deste Relatório, bem como pelas discussões e valiosas sugestões. Á Geóloga Adelina Arduíno de Magalhães, Elias Bernard do Espírito Santo e Leonardo Brandão Araújo, da DIGEOP, agradecemos pelo suporte na elaboração do SIG. Aos geólogos Ernesto Von Sperling e José Márcio Henrique Soares, da DIMARK, o nosso agradecimento pela concepção gráfica do SIG. As discussões estratigráficas e metodológicas com os colegas geólogos Eduardo Camozzato, Marco Aurélio Schneiders da Silva, Ricardo da Cunha Lopes e Wilson Wildner também foram de grande importância. Nos trabalhos de campo, o auxílio dos colegas Geólogo Carlos Alberto Kirchner e Técnico de Prospecção Edegar dos Santos Dias em muito contribuiu para a realização das campanhas num prazo otimizado. Também gostaríamos de agradecer aos colegas Técnico de Laboratório Valmor Justin pela confecção das lâminas delgadas, e Técnico de Prospecção Luiz Alberto da Costa e Silva pela coleta de zircões em algumas amostras. Á colega Bibliotecária Ana Lúcia Borges Fortes Coelho agradecemos pela normatização das referências bibliográficas e pelo auxílio na busca de material bibliográfico e aerofotográfico. Ao colega Geólogo Jorge Henrique Laux agradecemos pela revisão da versão preliminar deste Relatório. Ao Geólogo Johann Neveling (Council for Geoscience, South Africa) agradecemos pelo material bibliográfico sobre o Triássico da Bacia do Karoo. Á Bióloga Carolina Saldanha Scherer e à Geóloga Paula Camboim Dentzien Dias (Programa de Pós-Graduação em Geociências, UFRGS) agradecemos pelo empréstimo de material bibliográfico. Ao estagiário e graduando em geologia Jonathan Nereu Lisboa Rojas (Unisinos), pelo acompanhamento em campo, o nosso agradecimento.

2025, Rivista Italiana Di Paleontologia E Stratigrafia

In the Mount Messapion area (Chalkida, Greece) a continuous and expanded section of Triassic/Jurassic (T/J) limestone is exposed. This section consists of a 710 m thick pile of shallowing-upward peritidal cycles; the persistence of the facies and the lack of paleoenvironmental changes across the T/J boundary allowed studying the distribution of shallow water microfossils. The T/J boundary is placed in the upper part of the section defined by correspondence with (i) the last occurrence of Triasina hantkeni , (ii) the abrupt disappearance of megalodontid faunas and (iii) the presence of Early Jurassic microfossil assemblages. This paleontological reorganization happens suddenly, it is not controlled by any facies change, and surprisingly, it seems to produce no evident modification in the vertical stacking pattern of the cycles. A detailed facies analysis, performed along a 290 m thick stratigraphic interval (60 m above the T/J boundary and 230 m below), allowed the recognition of per...

2025, American journal of physical anthropology

The Homo erectus-like cranium from Buia (UA 31) was found in the Eritrean Danakil depression and dated to 1 million years. Its outer morphology displays archaic traits, as well as distinctive and derived characters. The present study provides the description and metric comparison of its endocranial anatomy. UA 31 was originally filled by a diffuse concretion. Following its removal and cleaning, the endocast (995 cc) was reconstructed after physical molding and digital scan. Its morphology is here compared with specimens belonging to different human taxa, taking into account endocranial metrics, cortical traits, and craniovascular features. The endocast is long and narrow when compared to the H. erectus/ergaster hypodigm, although its proportions are compatible with the morphology displayed by all archaic and medium-brained human species. The occipital areas display a pronounced bulging, the cerebellum is located in a posterior position, and the middle meningeal vessels are more deve...

2025, Geologia USP. Série Científica

Disponível on-line no endereço www.igc.usp.br/geologiausp -19 -Resumo Depósitos siliciclásticos da Formação Raizama de idade ediacarana-cambriana são expostos descontinuamente ao longo da margem sul do Cráton Amazônico e Faixa Paraguai Norte, centro-oeste do Brasil. Estes depósitos são interpretados por sucessões costeiras progradacionais, sobrepondo em conformidade os depósitos carbonáticos do Grupo Araras. A análise faciológica e estratigráfica da seção aflorante na região de Nobres, Estado do Mato Grosso, permitiu a individualização de dezessete fácies sedimentares agrupadas em cinco associações de fácies (AF): AF1) shoreface inferior consiste de arenitos com laminação plano -paralela e truncada por onda (microhummocky), intercalados por pelitos laminados, e com níveis bioturbados por tubos verticais perfurantes; AF2) shoreface superior, formada por arenitos com estratificação plano-paralela e cruzada swaley; AF3) submaré, composta por arenitos com estratificações cruzadas tangenciais e acanaladas com recobrimentos de siltito/arenito muito fino interpretados como depósitos de canal e barras; AF4) planície de maré é caracterizada por arenitos com estratificação cruzada tangencial e sigmoidal, laminação plano-paralela a cruzada de baixo ângulo, gretas de contração, intercalados por siltititos/arenito muito finos com acamamento flaser, organizados em ciclos de raseamento ascendente; e AF5) fluvial entrelaçado distal é constituída por arenitos com estratificação cruzada acanalada com lags lateralmente descontínuos, estratificações plano-paralelas e cruzadas de baixo-ângulo, parcialmente retrabalhadas por onda. A sedimentação da Formação Raizama indica que o fornecimento de sedimentos siliciclásticos estariam relacionado a soerguimentos no Cráton à noroeste da área estudada, sucedendo os depósitos carbonáticos do Grupo Araras. Traços fósseis tubulares descritos na AF1 indicam, pela primeira vez, a presença de traços fósseis perfurantes sugerindo uma idade deposicional para Formação Raizama mais próxima ao limite Ediacarano-Cambriano.

2025, Anuário do Instituto de Geociências - UFRJ

2025

The depositional environment, climatic conditions, structural evolution, age, catchment area characteristics, and sequence stratigraphic arrangement along an early Cenozoic forelandhinterland boundary in northeastern Spain were determined from sedimentologic, palynologic, stratigraphic, structural, and paleomagnetic data. As the transpressional Catalan Coastal Ranges (characterized by NNW-verging folds and thrusts) rose during the Paleogene, two fan-deltas prograded into the Ebro basin. The syntectonic condition of the Paleogene deposits is evidenced by facies and geometries directly related to the growth of specific structures and tectonic activity in the catchment area. A tectonosedimentary evolution was deduced along the basin margin, clearly indicating a NE to SW migration of the deformation. In the present study, the effects of high rates of subsidence and sediment supply, associated with orogenic uplift and loading, on the sequence-stratigraphic organization of two fandelta cl...

2025, CPRM

O conhecimento geológico do território brasileiro constitui um instrumento indispensável para o plane- jamento e a implementação das políticas públicas voltadas para o desenvolvimento sustentável dos recursos minerais, petrolíferos e hídricos subterrâneos do país e, simultaneamente, fonte de dados imprescindível para o conhecimento do meio físico tendo em vista a execução de estudos de zoneamento ecológico-econômico e de gestão ambiental do território nacional. É com esta premissa que a Secretaria de Geologia, Mineração e Transformação Mineral do Ministério de Minas e Energia, através da CPRM -Serviço Geológico do Brasil têm a grata satisfação de disponibilizar à comunidade técnico-científica, aos empresários do setor mineral e à sociedade em geral os resultados alcançados pelo PROJETO BACIA DO TUCANO CENTRAL, que compreende as FOLHAS CAIMBÉ -SC.24-Z-A-I e JEREMOABO -SC.24-Z-A-II. Executado pela Superintendência Regional de Salvador da CPRM -Serviço Geológico do Brasil, o projeto apresenta o estado da arte do conhecimento geológico e de recursos minerais na escala 1:100.000 de uma área de 6.000 km2, abrangendo terras dos municípios de Adustina,

2025

The Tithonian Pimienta Formation represents the main hydrocarbon source rock in Mexico, recently being targeted as an unconventional reservoir. This work shows the results of a detailed sedimentological characterization of the Pimienta Formation in the Tampico-Misantla Basin, Mexico.
This study integrates the well information, gamma ray log (GR), seismic interpretation and a high-resolution sedimentological analysis of an analogue outcrop core which involved facies identification, bio and chemostratigraphy. The continuous core covers the whole Pimienta Formation and its lower and upper stratigraphic boundaries (San Andres and Tamaulipas Inferior formations respectively).
Three stratigraphic members were recognized in the Pimienta Fm, the lower member consists mainly of saccocoma wackestone and calcispheres wackestone, with increasing GR values towards the top, suggesting a deposition on an outer platform to deep marine environment during early Tithonian time. The middle member comprises predominantly argillaceous carbonate mudstone and radiolarian wackestone, both with high organic matter, high V, Si and Al content and high GR values, indicating a deep marine environment and a middle Tithonian age. The upper member contains mainly bioclastic wackestone and mollusk-fragments wackestone with decreasing GR values towards the top and low organic matter content, implying an outer platform environment and a late Tithonian age.
According to their sedimentological features, both lower and middle members of the Pimienta Formation shows the best characteristics as an unconventional reservoir. This analysis contributed to identify sweet spots within the Pimienta Formation in the study area.

2025, Lithosphere

Tight sandstone reservoirs are widely distributed worldwide. The Upper Triassic Chang 6 member of the Yanchang Formation is characterized by low permeability and porosity. The facies model offers a unique approach for understanding the characteristics of various environments also heterogeneity, scale, and control of physical processes. The role of subsurface facies features and petrophysical properties was unclear. Notable insufficient research has been conducted based on facies and petrophysical modeling and that demands to refine the role of reservoir properties. To tackle this problem, a reservoir model is to be estimated using various combinations of property modeling algorithms for discrete (facies) and continuous (petrophysical) properties. Chang 6 member consists of three main facies, i.e., channel, lobe main body, and lobe margin facies. The current research is aimed at comparing the applicability and competitiveness of various facies and petrophysical modeling methods. Furt...

2025

2025, The Scientific Journal of University of Benghazi

Twenty-five samples were collected at 30 cm intervals from the studied cored interval within the limestone unit (AII)
reported at IODP Site U1376 on Burton Guyot. The purpose of this research is to examine and identify the coral and algae
suites in the studied core concerning sea level fluctuation during the Eocene time. This reef is isolated by being between
two volcanic units in the Southwest Pacific Ocean. Eleven biofacies units have been established based on the fabric of the
grains. The biofacies units are as follows; Algal-coral grainstone, foraminiferal algal-coral grainstone (Alabaminabed),
foraminiferal algal-coral packstone to grainstone (Heterostegina bed), algal-coral grainstone, foraminiferal algal
boundstone, foraminiferal algal grainstone (Lagena bed), foraminiferal algal grainstone (Cibicidoides micrus-bed),
foraminiferal algal boundstone to grainstone, foraminiferal algal-coral grainstone, algal echionoidal packstone, and
foraminiferal algal coral wacke-packstone. This is the first study to use both algae and coral in differentiating the units
mentioned above. The only coralline red algae recognized in the samples is Lithothamnion camarasae. This species is a
good indicator of the warm climatic conditions during the middle-late Eocene. The only species of coral found in these
units is Isopora togianensis, a scleractinian reef builder. The high percentage of algae compared to coral indicates a
climatic change from a greenhouse to an icehouse climate. The faunal trend during this time also indicates a tectonic
change.

2025, Journal of Environmental Protection

bstract
The competition between coral and algae in marine reefs is pervasive through
geologic time; that competition determines the structure and composition of
reef communities, which we see in the fossil record. However, the relationships between coral and calcareous algae in reefs are poorly understood. To
study this relationship, several hand samples and thin sections were examined
from nine different foralgal reef localities around the world. Foralgal reefs
typically extend from about 20 m depth or shallower on the seaward side of
the reef. The first section is Salt Mountain, Alabama, which preserves a Paleocene reef. It contains a high percentage of red coralline algae with benthic
foraminifera. The second section is IDOP-U1376, IIA Limestone, it is Middle
Eocene, in the form of an isolated reef sandwiched between two igneous beds.
The third section is the Utoe’ Limestone, New Caledonia, it is Middle Eocene
in age and is composed mainly of grain-boundstone units with some igneous
interlayered. The fourth section is the Darnah Formation in the West-Darnah
roadcut section, Northeast Libya, it is Middle Eocene in age, it is composed of
highly fossiliferous limestone (corals, red coralline algae, echinoids, mollusks,
foraminifers, and bryozoans). The fifth section, the Al Bayda Formation (Algal Limestone Member) in Northeast Libya, is in the Drayanah—Al Abyar
roadcut, Northeast Libya, it has several species of algae but also includes a
high percentage of buildups of coral species. The sixth section is the Oligo-Miocene Al Faidiyah Formation (Al Fatayah Cement Quarry) limestone
unit in Northeast Libya. The seventh section is (Core-core 20) late-early to
middle Miocene Limestone Unit-Cicuco Field, NW Colombia. The eighth
section is the Benghazi Formation at Benghazi Cement Quarry, in Northeast
How to cite this paper: Khameiss, B.,
Fluegeman, R., Hoyt, W., Malone, S. and
Muftah, A. (2024) Competition between
Coral and Algae in Tertiary and Quaternary Reefs: Greenhouse to Icehouse Transitions. Journal of Environmental Protection,
15, 94-107.
https://doi.org/10.4236/jep.2024.151007
Received: March 21, 2023
Accepted: January 28, 2024
Published: January 31, 2024
Copyright © 2024 by author(s) and
Scientific Research Publishing Inc.
This work is licensed under the Creative
Commons Attribution International
License (CC BY 4.0).
http://creativecommons.org/licenses/by/4.0/
Open Access
B. Khameiss et al.
DOI: 10.4236/jep.2024.151007 95 Journal of Environmental Protection
Libya, it is fossiliferous limestone, consisting of coral, algae, mollusks, and
echinoids. The ninth and tenth sections are Quaternary reefs in the Bahamas
and the Florida Keys, respectively. These reefs contain a high percentage of
coral, red coralline algae, echinoids, mollusks, foraminifers, and ostracods.
Based on the data and static analysis results on the thin sections and hand
specimens, this study determines the occurrence and outcomes of coral-algal
interactions among different coral growth forms (branching, upright, massive, encrusting, plating, and solitary). The Early Paleogene (Paleocene to
Eocene) has the highest percentage of algae in two forms (crustose and frondose), which is a good indicator of a warm climate. In the Middle Eocene to
Late Eocene, coral replaced algae in different localities in sections of that age.
This change is an indicator of climatic cooling, especially in the western Lutetian Darnah section. In the Oligocene time, high-branching corals became
abundant and escaped competition with the algae due to Icehouse conditions,
as shown in the Al Bayda Formation. In the Miocene, coral species started to
decline because of the return to Greenhouse conditions. Coral can lose its
competitive edge when chemical and physical defense systems reduce growth
and production due to warming. On the other hand, crustose-form algae attract the larvae of the coral. Algae induce them to get a more highly competitive frondose form, which is useful for corals as they decrease growth and
production. Algae can quickly colonize the dead reef by using the firm substrate to rebuild themselves. This research may prove valuable when predicting the response of modern coral reef systems to future climatic warming
conditions and provides a model for what future reefs may look like.
Keywords
Utoe’ Limestone, New Caledonia, Benghazi Formation at Benghazi Cement
Quarry, Is IDOP-U1376, IIA Limestone, It Is Middle Eocen

2025, Mühendislik Bilimleri ve Tasarım Dergisi

The Kargı-İskilip Eocene deposits located in southern part of the North Anatolian Fault are very well exposed between Kargı and Çorum settlements in N-Turkey. These Eocene deposits are observed as submarine fan and fan delta systems. Submarine fan system is characterized by clastic sediments such as conglomerate, sandstones, siltstones, greyish coloured shale and mudstone alternations. Fan delta system is represented by pebbly sandstones, siltstones and coal seams in some parts. In this study, Kargı-İskilip Eocene sediments involved in İskilip Group were examined in detail (Hacıhalil, Yoncalı and Karabalçık formations). Thus, the sedimentary facies indicating depositional environments and processes were revealed. For this research, six measured sedimentary sections (MSS) have been taken systematically and eight sedimentary facies are described and interpreted. The facies changes in vertically and laterally indicate that Kargı-İskilip Eocene deposits present as regressive character f...

2025

The interaction of geological and anthropic processes shaping the urban growth of Ferrara and the evolution of the surrounding plain. (IT ISSN 0394-3356, 2010) The town of Ferrara is placed at the junction of the alluvial plain of the Po River, the innermost portion of the Po River delta plain, and the alluvial plain fed by the Reno River and other Apennines-derived streams. The depositional evolution of the fluvial system largely affected the urban shape, but human intervention in turn modified the river dynamics, to eventually subjugate it into the present-day artificial state. Ferrara is the only city of the Emilia region not sharing Roman or a pre-Roman origin; the future urban region was nevertheless well populated during ancient times. During Roman times major artificial intervention was performed on the natural river framework, through long canal digging and river embankment. After the fall of the Roman Empire, a major restructuring of the river drainage system took place, leading to the development of two new distributary channels. Ferrara nucleated during the early Middle Ages (7 th century), near the divergence point of these channels, as a Byzantine fortified structure, built on a crevasse splay, part of the northern levee body of the main Po channel of the time. The southern side of the fortified village, was about 240 m long, its area 35,000 squared metres. The proto-urban structure then grew in a linear way, on the levee crest, because the elevated site offered protection against flooding waters and provided comparatively firm and well drained ground. During the first half of the 11 th century, the urbanised area on the northern levee broadly stretched over a distance of about 2300 m, with a width of often less than 100 m. Also the southern levee of the Po di Ferrara was progressively built over, during the Middle Ages. At the beginning of the 12 th century, the present-day Po channel, flowing at the north of the town, was generated through a river reorganisation phase traditionally known as Rotta di Ficarolo. During the same century, the Romanesque cathedral was founded, at the distal edge of the sedimentary levee complex. During the following centuries, the early growth way of the urban tissue through individual building cell implantation gave way to discrete episodes of town growth and district planning. Land reclamation works made the expansion of the urban area toward interfluvial argillaceous depressions possible. At the ending of the 15 th century, this northward expansion culminated into a large Renaissance expansion (Addizione Erculea). During the following century, the water flow in the southern Po delta channels was suddenly terminated by an ill-fated attempt to artificially force the Reno River to reach the sea through the former Po di Primaro channel. The very low topographic gradients and the elevated sediment load transported by this Apennines-derived river rapidly silted up the ancient Po di Ferrara channel, just at the west of the town. Large marsh therefore developed in the areas surrounding the town. After a long period of stagnation, the urban growth restarted only during the 20 th century, in ways utterly unaware of the geological and environmental constrains and thus exposed to significant level of environment hazards, such river floods and earthquakes.

2024

Cuatro Cienegas is a natural geopark that exhibits a vast reservoir of geological, geochemical and geobiological diversity, including shallow-water microbial carbonates with clotted micrite textures known as thrombolites. Thrombolites mainly occur as domes and massive irregular carbonates along the margins of Rio Mezquites in Cuatro Cienegas, northern Mexico. Because their clotted textures result from diverse abiotic and biotic interactions at the microbial–mineral interface, the formation of clots in thrombolites continues to be a contentious issue. Through a petrographic, scanning electron microscopy and bulk biogeochemical analysis, this study investigated the role of endolithic cyanobacteria in the generation of thrombolitic clots. Their microclotted fabric is characterized by 50 to 200 μm peloidal clots, pores, fenestrae, crevices and cavities as main components. Thrombolites also contain microbial microstructures, some of them interpreted as the endolithic contribution to the genesis of clotted micrite. Thrombolites and associated fresh microbial mats are composed of cyanobacteria, green algae and diatoms. Petrography and cast-embedded scanning electron microscopy micrographs also show the presence of filamentous endolithic cyanobacteria inside the thrombolitic framestone. The geochemical bulk characterization for carbon and oxygen isotopes shows average values of −0.7‰ Vienna PeeDee Belemnite and −8.0‰ Vienna PeeDee Belemnite, respectively. The organic matter preserved in their mineral matrix and associated microbial mats indicated the putative presence of cyanobacterial hopanoids. The high diversity of peloids and the microboring evidence, together with observed microstructures, suggest that clots may also form by the concurrent precipitation and dissolution of the thrombolites. Among the known sources of peloidal clots, microbial boring may be an additional micrite source for clot formation. Microbial carbonate dissolution may also promote heterogenous lithification by hydration and dehydration cycles. Thrombolites reflect complex systems due to concurrent interactions among producers (phototrophs), consumers (small invertebrates), mineralization (carbonate precipitation induced by phototrophs) and endolithic dissolution. The microstructures inside thrombolites, in conjunction with biogeochemical attributes of bulk thrombolites, may provide unambiguous sedimentary biosignatures.

2024

Dissertação (mestrado)—Universidade de Brasília, Instituto de Geociências, 2013.O Grupo Araí, composto por um conjunto de rochas metassedimentares e metavulcânicas, de baixo grau metamórfico, sobreposto a Suíte Aurumina e a Formação Ticunzal, constitui uma sucessão depositada em uma bacia do tipo rifte intracontinental passivo, cuja evolução iniciou antes de 1,77 Ga no Paleoproterozóico. Esse grupo foi subdividido, classicamente, em Formação Arraias (sequência continental) e Formação Traíras (sequência marinha). Entretanto, a análise, compilação e integração dos dados geológicos no que tange à geologia sedimentar e a tectono-estratigrafia, mostraram a necessidade de subdividi-lo em quatro unidades: Água Morna, Arraias, Caldas e Traíras. A Formação Água Morna representa um sistema deposicional fluvial entrelaçado do tipo Saskatchewan Sul, instituído em uma bacia contexto tectônico da fase pré-rifte, representando a Tectonossequência Água Morna submetida a processos de subsidência ter...

2024, The Journal of the Geological Society of Japan

The stratigraphy of the lower-middle Miocene Kuma Group of Shikoku, southwestern Japan, was reexamined on the basis of geological field observations of the previously defined Shimosakabatoge Formation and the Tomishige Formation. The redefined Kuma Group consists of, in ascending stratigraphic order, the Furuiwaya Formation, composed mainly of clasts of Sambagawa metamorphic rocks, and the Myojin Formation, mainly sandstone and granite clasts. The lithofacies of the Shimosakabatoge Formation and its depositional age, as deduced from its clasts and the ages of igneous rocks that intrude the formation , suggest it is part of the Furuiwaya Formation. The previously proposed stratigraphy of the Kuma Group, in which the Tomishige Formation was placed at the top of the group, is questionable. The relationships between the Kuma Group and the lower Eocene Hiwadatoge Formation is revealed as an unconformity.

2024

A thin layer of carbonate breccia, with limestone fragments in a red clay and calcite matrix, lies between Pliocene-Pleistocene basaltic lava and Danian limestones. Rare basaltic pieces suggest peperite formation due to lava interaction... more

2024, Journal of the Geological Society of India

A long and continuous palaeo-course of Assi River, in between Prayagraj and Varanasi, in the Ganga River plains with indications of good groundwater potential had been traced from remote sensing data. Electrical Resistivity Tomography (ERT) has been conducted along eight lines for confirmation of the same palaeo-course in general and to specifically ascertain the nature of the course-the past flow conditions and the type of deposits. The variation in the thickness of channel deposits along the concave and convex banks and the middle parts is an indication of lean flow. The mixed fractions of channel deposits are an indication of dumping of sediments in the dying stages of a river. The ERT investigation has further helped in delineating the high resistive palaeo-channels (20 to 50 Ohm.m), the low resistivity aquiclude clay layer (<15 Ohm.m) and the deeper and relatively higher resistivity sandy layer (>50 Ohm.m), which could be the principal aquifer in the area.

2024, Arab J Geosci

A calcrete horizon, 3-10 m thick, is found exposed in northern Jordan in three localities, Rumman, Marsa', and Wasfi At Tal forest (WTF). It is situated at the base of the dominantly limestone, Late Cenomanian Hummar Formation, separating it from the underlying marly Fuheis Formation. The calcrete horizon exhibits all the diagnostic features characteristic of calcrete, such as diagenetic pisoids; a mottled or clotted texture; circumgranular cracks around grains in a nodular texture; pendant or microstalactitic cement; meniscus cement; plant roots or rhizogenic structures, both longitudinal and transverse; exfoliation on boulder and cobbles; alagally laminated hard pans; and abundant dissolution of cracks and vugs. Consequently, it represents a subaerial erosional unconformity and type 1 sequence boundary (SB) that was not previously noticed. The Hummar Formation is considered as a third-order sequence with the SB at the base of the calcrete horizon, while the calcrete horizon itself forms the lowstand system tracts (LST). The transgressive systems tracts (TST) involve the lower two third of the Hummar Formation ending with peloidal grainstone representing the maximum flooding surface (MFSs). The rest of the formation is the falling highstand systems tracts (HST). The next SB is not seen due to a thick soil-covered gap. The calcrete horizon formed due to the formation of a paleohigh, in the study area, associated with the compression produced by the initial subduction of the Afro-Arabian Plate under the Eurasian Plate during the Late Cenomanian, slightly earlier than the previously known Turonian subduction and compression.

2024, Iraqi Bulletin of Geology and Mining

Late Oligocene-Early Miocene rocks are not previously known in the High Folded Zone,especially in northeast Iraq; neither in outcrops nor in subsurface sections. In most areas, theexposures of the Pila Spi Formation (Middle-Late Eocene) are overlain usually by theexposures of the Fat'ha Formation (Middle Miocene). Recent field observations and lithostratigraphic study, of an area near Basara Gorge, south of Sulaimaniyah, Northeast Iraq, revealed the presence of a succession (20-25 m thick)between thePila Spi and Fat'ha formations. This succession has unconformable contact with the underlying Pila Spi Formation, marked by the presence of (6-8) m thick, sedimentary breccias and conglomerate indicating the presence of rocks of different ages. The succession consists of two main parts; the lower part consists of breccia, conglomerate, and red sandstone and claystone, whereas the upper part consists of fossiliferous limestone interbedded with green marl. Micropaleontological studies, of samples collected from the studied succession, proved the presence of Late Oligocene-Early Miocene rocks between the Pila Spi Formation(Middle-Late Eocene) and Fat'ha Formation (Middle Miocene), with indication of mixing environments (basinal/ shelf). The lithological diversity indicates the presence of a break in sedimentation, indicated by breccia and conglomerate over the Pila Spi Formation. Moreover, the cyclic repetition of green marl with limestone indicates oscillation of the sea level during deposition of the studied succession. This is the first time to recognize rocks with such age and mixed environments from the areas of the High Folded Zone in Sulaimaniyah Governorate, Northeast Iraq.