Uppermost Part Research Articles

Investigating the Structure of Detachment Faulting and Its Role in Ore Formation: The Kallintiri Detachment System and the Associated Polymetallic Ore Deposit (Rhodope, NE Greece)

The Kallintiri area (SW Byala Reka–Kechros Dome, Rhodope) hosts a polymetallic (critical, base, and precious metals) ore deposit, tectonically controlled by the late Eocene–Oligocene, top-to-SW Kallintiri Detachment System. The earliest structure associated with the Kallintiri Detachment is a ductile shear zone at the interface between the high-grade footwall gneisses of the Lower and Intermediate Rhodope Terranes. The detachment zone encompasses the uppermost part of the gneisses and the ultramylonitic Makri Unit marble. The marble is bound by a brittle–ductile shear zone at the base and a knife-sharp, low-angle normal fault at the roof, exhibiting considerable brecciation and ultracataclasite development. The hanging wall includes the Makri Unit phyllites and the overlying mid–late-Eocene–Oligocene supra-detachment sediments, which show syn-depositional slump structures and brittle deformation with low- and high-angle faulting and non-cohesive cataclasites. Extensive hydrothermal fluid circulation along the detachment zone and through NW tension gashes and high-angle faults led to pronounced silicification and ore deposition. Field observations and mineralogical and geochemical analyses revealed two primary types of ore mineralization spatially and temporally associated with different structures. Base and precious metals-rich ores are associated with the detachment, while Sb ore deposition is localized mostly within the NW-trending tension gashes and high-angle faults.

The first ornithocheiromorph humerus from Wuerho (Urho), China, with a new isotopic age of the Tugulu Group

Abstract Pterosaur remains are rare from the lowermost Cretaceous, hampering our understanding of the taxonomic and morphological diversities of pterosaurs during this period. The Lower Cretaceous Tugulu Group in Wuerho, China is renowned for hosting the Wuerho Pterosaurian Fauna (WPF), which has so far yielded numerous fossil remains of two dsungaripterid pterosaurs, Dsungaripterus weii and Noripterus complicidens. Here we report a partial ornithocheiromorph humerus from the WPF, representing a deeply divergent clade from Dsungaripteridae. The scarcity of ornithocheiromorphs from the WPF might be interpreted by niche partitioning with dsungaripterids. Meanwhile, we also report a U-Pb zircon age of 134.27 ± 0.36 Ma dated by LA-ICP-MS for the tuffaceous layer at the uppermost part of the Shengjinkou Formation, confirming the Valanginian age of the WPF presented by a previous study. The Wuerho region is one of the few localities producing abundant pterosaur fossils and the only one with an earliest Cretaceous age. The new finding here also suggests that Ornithocheiromorpha had rapidly diversified and achieved a global distribution during the earliest Cretaceous, presumably through a series of modifications on the locomotor apparatus including the warped deltopectoral crest of the humerus, which might substantially improve their flight efficiency.

Sedimentation rates, coastal delta accretion, and stratigraphic datum of the Late Pleistocene–Mid-Holocene transition in the East Equatorial Atlantic: New concept from calcareous nannoplankton

This study examines the sedimentation rates (SR) during the last 20 kyr in the Niger Delta using selected biostratigraphic datum levels. Three gravity cores (GCs) collected at −40 m below sea level from the shallow offshore Niger Delta (GC1 = Western, GC2 = Central, and GC3 = Eastern) were analysed for their calcareous nannoplankton species ( Emiliania huxleyi, Gephyrocapsa oceanica, Helicophaera sellii and Reticulofenestra asanoi). Successive datums were established mainly from the informal biozones and ranges of Gephyrocapsa oceanica and Emiliania huxleyi marker species due to their abundance. By correlating the First Occurrence (FOC) and Last Occurrence (LOC) datums of the marker species in the cored sequences (GCs), SRs were reconstructed. Based on the constructions, the FOC of Gephyrocapsa oceanica (20 kyr) reflects a position towards the bottom of the GCs, the FOC of Emiliania huxleyi (11–8.5 kyr) delineates the middle of the GCs, and the LOC of Emiliania huxleyi (6.5 kyr) marks the uppermost part of the GCs. The sediment load by average calculated from each location in the Western, Central, and Eastern Niger Delta shows sequences of sedimentation rates of ~36.7 cm/kyr for the late Pleistocene, ~174 cm/kyr for the early Holocene, and ~18.6 cm/kyr for mid-Holocene time periods. Consequently, on average, ~229.3 cm/kyr of sediment were deposited at −40 m water level over the last 20 kyr, with the early Holocene experiencing the highest sedimentation rates (~174 cm/kyr) across the three locations. Additionally, this study provides evidence that the Niger Delta sink deposits responded to the West African Monsoon (WAM) driven sedimentation rates during the late Quaternary (20–6.5 kyr). Furthermore, this sediment deposit facilitated the development of a high-resolution age-depth and sedimentation rate model linked to the regional sea level of the Eastern Equatorial Atlantic that succinctly delineates the late Pleistocene and early Holocene boundary of the Niger Delta. The outputs of this study bridged the research gap and knowledge on the impact of coastal accretion and depositional processes on sedimentation rates in the shallow offshore Niger Delta.

Deciphering the dynamics of a Younger Dryas rock avalanche in the Bernese Alps

Large rock avalanches play a key role in shaping alpine landscapes. However, the complex interplay between mass movement and other surface processes poses challenges in identifying these deposits and understanding the underlying process controls. Here, we focus on the rock avalanche deposit of the Lurnigalp valley in the Bernese Alps (Switzerland), originally mapped as till. The Lurnigalp valley is a U-shaped tributary valley located in the southwest of Adelboden, Canton Bern. To explore the timing and dynamics of the rock avalanche event, we employed detailed remote and field mapping, sedimentary petrology, surface exposure dating with cosmogenic 36Cl, and runout modelling with DAN3D®. For the reconstruction of the chronology, we analyzed cosmogenic 36Cl in surface samples from 15 boulders of the rock avalanche deposit. We developed three distinct scenarios to investigate the dynamics and contextual conditions of the rock avalanche event. In the first scenario, we consider a rock avalanche depositing 1 Mm3 of sediment in a valley devoid of ice. The second scenario uses the same deposit volume but introduces a hypothetical glacier occupying the uppermost part of the valley. Finally, the third scenario, similar to the first scenario with a glacier-free valley, assumes a substantially larger volume of collapsed rock mass. We consider the third scenario the most plausible, in which approximately 6 Mm3 of rock mass, composed of limestone and sandstone, was released from a limestone cliff around 12 ± 2 ka during the Younger Dryas. The collapsed rock mass fell into the ice-free valley floor, ran up the opposite valley side and was deflected towards the northeast following the valley orientation. The rock mass stopped after 2.2 km leaving approximately 6.4 Mm3 deposits spread across the entire valley floor. Subsequently, most of the rock avalanche deposit have been reworked by periglacial activity. We suggest that structural features, lithology and glacial erosion and debuttressing were involved in the weakening of the in-situ bedrock that finally led to the collapse. Our study not only enhances the understanding of rock avalanche mechanisms and their profound impact on Alpine landscape evolution but also elucidates the complex interplay of geological processes that led to the collapse and altered the rock avalanche deposit afterwards.

Late Triassic sedimentary environments and detrital zircon provenance analysis in the Amdo area of the Tibetan Plateau: Implications for the evolution of the Meso-Tethys Ocean

Aspects of the early Mesozoic evolution of the Meso-Tethys Ocean remain uncertain, and detrital zircon provenance analyses may be useful for constraining the development of this region. In this paper, we describe Late Triassic sedimentary facies, petrography, geochemistry, and detrital zircon UPb geochronology for the Tumengela Formation (South Qiangtang Basin) and the Quehala Formation (Amdo back-arc basin) in the Tibetan Plateau. In Late Triassic times, the South Qiangtang Basin was characterized by marine deltaic environments adjacent to an evaporative platform, whereas the Amdo back-arc basin was characterized by a shallow marine shelf fringed by tidally-influenced deltas; in both basins, marine palaeoenvironments first deepened and then shallowed. By analyzing the characteristics of detrital zircon UPb age spectra for each microcontinent on the northern margin of Gondwana, and combining them with previously published data, we infer that the North and South Qiangtang Terranes amalgamated in Late Triassic times, and were separated from the Lhasa Terrane by the wide Meso-Tethys Ocean. During the Late Triassic, the Meso-Tethys Ocean began to be subducted, and the southern edge of the South Qiangtang Terrane developed as an active continental margin. The Quehala Formation accumulated in the back-arc basin of the Amdo microcontinent during subduction of the Meso-Tethys Ocean, and the uppermost part of Member 2 of the Quehala Formation is dated as no older than Early Jurassic.

Paleoceanographic changes across OAE 2 inferred from resilient foraminifera and XRF data at southern high latitudes (IODP Sites U1513 and U1516, Mentelle Basin, SW Australia)

The Oceanic Anoxic Event 2 (OAE 2), across the Cenomanian-Turonian boundary interval, was characterized by global environmental perturbations in the carbon cycle that affected the abundance and biodiversity of marine biota and their paleoecological preferences. International Ocean Discovery Program (IODP) Sites U1513 and U1516 in the Mentelle Basin (offshore SW Australia) reveal a continuous foraminiferal record that document the adaptative response of biota, suitable to reconstruct paleoenvironmental conditions in the water column and at the seafloor. Below and during the initial part of the OAE 2, we do not observe changes in the benthic foraminiferal assemblages dominated by Gavelinella, Gyroidinoides and Stensioeina. Agglutinated foraminifera are rare, whereas Microhedbergella and Muricohedbergella dominate the planktonic foraminiferal assemblage, indicating possible eutrophication episodes below and during the OAE 2 associated to an increase in terrigenous sediments. However, a positive peak in Zr/Rb ratios, the unique occurrence of Stensioeina truncata, and the increase in epifaunal- infaunal ratio, particularly at Site U1516, indicate a greater eolian transportation of sediments and an enhanced oxygenation at the seafloor, which might be related to the identification of the Plenus Cold Event (PCE) at high latitudes. An interval of low CaCO3 content within the peak of OAE 2 is characterized by the absence of foraminifera and dominance of siliceous organisms. It is also marked by a sudden enhancement of the hydrological cycle, probably causing a shoaling of the Calcite Compensation Depth (CCD). However, Site U1516 shows few samples with a change in the planktonic and benthic foraminiferal assemblage.Above this interval, both sites are characterized by a different benthic foraminiferal assemblage with the occurrence of Conorboides claytonensis in the uppermost part of OAE 2. At Site U1513, epi-infaunal ratio increase, planktonic foraminifera show the highest diversification, rainfall decreases, indicating a recovery towards a well-stratified water column with mesotrophic regimes and a drier environment, whereas Site U1516 shows a slower recovery.

Rapid India–Asia Initial Collision Between 50 and 48 Ma Along the Western Margin of the Indian Plate: Detrital Zircon Provenance Evidence

Constraining the collision timing of India and Asia requires reliable information from the coeval geological record along the ~2400 km long collisional margin. This study provides insights into the India–Asia collision at the westernmost margin of the Indian Plate using combined U-Pb geochronological data and sandstone petrography. The study area is situated in the vicinity of Fort Munro, Pakistan, along the western margin of the Indian Plate, and consists of the Paleocene Dunghan Formation and Eocene Ghazij Formation. The U-Pb ages of detrital zircons from the Dunghan Formation are mainly clustered between ~453 and 1100 Ma with a second minor cluster between ~1600 and 2600 Ma. These ages suggest that the major source contributing to the Dunghan Formation was likely derived from basement rocks and the cover sequence exposed mainly in Tethyan Himalaya (TH), Lesser Himalaya (LH), and Higher Himalayan (HH). Petrographic results suggest that the quartz-rich samples from the Dunghan Formation are mineralogically mature and have likely experienced log-distance transportation, which is possible in the case of an already established and well-developed river system delivering the sediments from the Craton Interior provenance. Samples of the overlying Ghazij Formation show a major detrital zircon age clustered at ~272–600 Ma in the lower part of the formation, comparable to the TH. In the middle part, the major cluster is at ~400–1100 Ma, and a minor cluster at ~1600–2600 Ma similar to the age patterns of TH, LH, and HH. However, in the uppermost part of the Ghazij Formation, ages of <100 Ma are recorded along with 110–166 Ma, ~400–1100 Ma, and ~1600–2600 Ma clusters. The <100 Ma ages were mainly attributed to the northern source, which was the Kohistan-Ladakh arc (KLA). The ~110–166 Ma ages are possibly associated with the TH volcanic rocks, ophiolitic source, and Karakoram block (KB). The Paleozoic to Archean-aged zircons in the Ghazij Formation represent an Indian source. This contrasting provenance shift from India to Asia is also reflected in the sandstone petrography, where the sample KZ-09 is plotted in a dissected arc field. By combining the U-Pb ages of the detrital zircons with sandstone petrography, we attribute this provenance change to the Asia–India collision that caused the provenance shift from the southern (Indian Craton) provenance to the northern (KLA and KB) provenance. In view of the upper age limit of the Ghazij Formation, we suggest the onset of Asian–Indian collision along its western part occurred at ca. 50–48 Ma, which is younger than the collision ages reported from central and northwestern segments of the Indian plate margin with 70–59 Ma and 56 Ma, respectively.

Cambrian-Ordovician trace fossils of the Basissletta region, northeast Spitsbergen, Svalbard

Trace fossils of the Cambrian–Ordovician sedimentary succession of the Basissletta region, northeast Spitsbergen, Svalbard, belong to three ichnoassemblages. The first one, composed of Monocraterion and Diplocraterion, belongs to the Skolithos ichnofacies and characterises sandstones of the Tokammane Formation (lower Cambrian: Terreneuvian) deposited in a shallow subtidal setting. The overlying carbonates with pseudomorphs after evaporites (uppermost part of Terreneuvian and the Cambrian Series 2) display abundant Balanoglossites. These beds were deposited in an oxygenated but hypersaline environment. The younger Ordovician carbonates of the Kirtonryggen Formation and the mixed carbonate-clastic deposits of the Valhallfonna Formation display a more diverse but poorly preserved trace fossil suite (Phycodes, Curvolithus, Planolites, Palaeophycus) typical of the archetypal Cruziana ichnofacies. Some parts of the succession are not bioturbated, and these are characterised by dark coloured fine-grained sediments with primary lamination. They were mostly deposited between the normal and storm wave base or below the storm wave base in oxic to anoxic environments.

Stratigraphic overview of the Neogene Transylvanian Basin, Romania

Although the Transylvanian Basin is often referred to as part of the Miocene Pannonian Basin System, we point out important tectonic and sedimentary differences reflected in the stratigraphy. The Neogene of the Transylvanian Basin can be split into two tectonic megasequences: Lower Miocene and Middle to Upper Miocene. The Early Miocene onset of the back-arc extension in the Pannonian Basin was not observed in the Transylvanian Basin, where shallow to deep-marine sediments were deposited in a flexural basin. Diverse types of facies developed in the continental (e.g. Sânmihai) and marine (e.g. Coruș, Chechiș, Hida) Lower Miocene formations. Although these are poorly constrained to the standard biostratigraphy, recent 87 Sr– 86 Sr data support their poor correlation with the Burdigalian. The Middle Miocene extension in the Transylvanian Basin is very weak compared with that in the Pannonian Basin. As the high-resolution Middle Miocene regional biostratigraphy of the Badenian and Sarmatian was calibrated by magnetostratigraphy and radiometric dating of the volcanic tuffs up to the Serravallian/Tortonian boundary, the influence of the regional tectonics on the basin's evolution and stratigraphy can be better understood. The regional tectonics produced a progressive basin isolation starting with the late part of the Middle Miocene. The uplift of the Carpathians isolated the basin at the beginning of the Pannonian and initiated the fan delta, lacustrine and fluvial sedimentation. The basin was rapidly uplifted and eroded while post-extensional subsidence was still ongoing in the Pannonian Basin. Endemic fossil assemblages allow only regional-scale correlations for this interval. The uppermost part of the stratigraphic record is represented by the volcano-sedimentary formations generated by the late evolution of the Eastern Carpathians. The sedimentation and subsidence pattern of the Transylvanian Basin reflect the effect of retreating subduction zone in the Eastern Carpathians.

Discovery of the enigmatic taeniopterid plant Ilfeldia from the lower Permian of North China and its palaeophytogeographical implications

ABSTRACT The recognition of plant biogeographic ranges over time and migration routes is crucial for understanding ancient global plate tectonic configurations. This paper deals with a new fossil plant from the uppermost part of the Taiyuan Formation (earliest Asselian) in the Wuda Coalfield, Inner Mongolia, China. It has a taeniopterid morphology comprising strap-shaped leaves with a prominent midrib and arching secondary veins, and it exhibits dimorphism between its fertile and vegetative leaves. The fertile leaf has a slightly lobed margin, with each lateral vein terminating in a marginal lobe that bears a synangium. Each synangium consists of primarily two, occasionally three, oval sporangia. Based on these distinctive characteristics it is identified as a new species of Ilfeldia. Previously, Ilfeldia had a highly restricted record in the Upper Pennsylvanian of Portugal and Germany into the lower Permian of Germany. The sedimentary and floral context suggests Ilfeldia was a xerophilous element that underwent long-distance dispersal during the Late Pennsylvanian to earliest Asselian, migrating from Gondwana (Iberia) to Cathaysia (North China) via Euramerica (Eastern Avalonia). The palaeogeographical distribution over time of Ilfeldia supports the continental model of the Wegenerian Pangaea configuration and underscores the continental connection between Euramerica and Cathaysia in the Late Pennsylvanian.

Latest Triassic Active Aeolian Dune Field Preserved by CAMP‐Related Lava Flows

ABSTRACTFieldwork investigations and stratigraphic analyses in the Parnaíba Basin, northern Brazil, reveal the interaction of the uppermost part of the Triassic Sambaíba aeolian dune field (erg) system with the latest Triassic–earliest Jurassic Mosquito lava flows. The lava flows originated as part of the Central Atlantic Magmatic Province (CAMP, ~201 Ma) and covered the aeolian system, allowing almost complete preservation of large‐scale in situ aeolian bedforms, even preserving lee‐ and stoss‐side. During the emplacement, the lava flows interacted with unconsolidated aeolian sediment, generating sediment–lava deformation features that are preserved at the interface between these units. This occurrence attests to arid conditions in the low latitudes of Gondwana at the Triassic–Jurassic transition.

Palaeogeographical and eodiagenetic settings of host‐replacing phreatic calcrete intervals developed in mud deposits of the Famennian Kinnesswood Formation in the Pennyseorach Subbasin of south‐west Scotland

ABSTRACTIn the Pennyseorach Subbasin of south‐west Scotland, the Famennian Kinnesswood Formation of the Inverclyde Group includes several, ca 1 to 3 m thick erosional remnants of host‐replacing phreatic calcrete hardpans developed in mud deposits. The latter are most unusual hosts for such calcretes due to their relative impermeability, which would normally prevent them from sufficiently accommodating the circulation of an aquifer. In previously documented phreatic calcretes, mud deposits clearly acted as aquicludes that sharply constrained calcrete development. In the Kinnesswood Formation at Pennyseorach, tall desiccation fissures allowed groundwater to circulate in thick, semi‐consolidated mud deposits. Because of the inferred development of an adjacent evaporitic basin, the mixing of fresh and evaporitic groundwaters raised the pH enough for the replacement of phyllosilicates by calcite to occur along the fissure walls, forming ‘fissure calcretes’. The latter gradually expanded and eventually coalesced into mature, ‘columnar host‐replacing phreatic calcrete hardpans’ in which 90 to 100% of the muddy host material was replaced by calcrete. At Pennyseorach, host‐replacing phreatic calcrete hardpan formation not only affected the transition zone between the Doughend Sandstone and Foul Port Members of the Kinnesswood Formation (the Dunagoil Calcrete interval), as in other localities of south‐west Scotland, but also affected the uppermost part of the formation, which is marked by several erosion surfaces downcutting into columnar host‐replacing phreatic calcrete hardpan intervals in association with the episodic rise and fall of base‐level. These newly recorded host‐replacing phreatic calcrete hardpan intervals from the upper part of the Kinnesswood Formation have a tightly constrained stable isotopic signature that is distinct from that of both the Dunagoil Calcrete and the successive host‐replacing phreatic calcrete hardpans of the Visean Clyde Sandstone Formation within the same group, underlining their potential as stratigraphic markers and palaeoenvironmental indicators.

Calcareous nannofossil and U-Pb zircon geochronological data on the Coniacian–Santonian in a part of the Central Srednogorie Zone (central South Bulgaria)

The calcareous nannofossil assemblages in three sections (Dalgi Rid, Milkova Cheshma and Toplika) of the clayey-carbonate Mirkovo Formation in the Central Srednogorie Zone have been investigated. These sections were specifically chosen because, at their basal parts, they contain silica-manganese (± iron) mineralisations, which, according to recent studies, may prove useful for investigations into their potential as a source of ore and critical elements. The nannofloras exhibit very poor preservation and comparatively-low taxonomic diversity. Nevertheless, the presence of some biostratigraphically-significant taxa has been detected. Micula staurophora occurs consistently in sections Dalgi Rid and Milkova Cheshma, which, in the absence of Lithastrinus grillii, indicates the middle to late Coniacian UC10. The latter species was recognised, with a relatively-consistent stratigraphical range, in section Toplika. Although Lithastrinus septenarius and Arkhangelskiella cymbiformis are absent at Toplika, the studied sediments could not confidently be assigned solely to UC12, and thus a tentative late Coniacian (pars.)–Santonian (pars.) age was adopted for the strata in this section. This is consistent with the obtained LA-ICP-MS U-Pb age (86.2±1.4 Ma) of the youngest zircons from the volcaniclastics in the uppermost part of the Chelopech Formation at the same locality, immediately below the boundary with the overlying Mirkovo Formation.

Anatomical Variations of the Jugular Bulb: A Critical and Comprehensive Review.

Background and Objectives: The jugular bulb (JB) is the uppermost part of the internal jugular vein receiving the sigmoid sinus. The aim of the present research is to aid the comprehension of the JB, its abnormalities, and surrounding structures for improving both academic and surgical awareness. Materials and Methods: Various studies on this topic were critically reviewed. Cone-beam CT scans and CT and MR angiograms were used to demonstrate each type of the discussed variations. Results: Variations in the JB anatomy were thoroughly documented: high JB, dehiscent JB, hypoplasia and hyperplasia, and diverticula of the JB, as they have significant clinical implications, particularly in the context of otological and neuro-otological surgery, skull base pathology, and diagnostic imaging. Definitions and critical arguments were also specified to clarify existing literature. Additionally, we present a case report illustrating a high and dehiscent JB, an anatomical variation of clinical interest due to its potential for misdiagnosis as a glomus tumor. Another case describes a dehiscent JB with a hypotympanic air cell protruding into it, further highlighting the variability of this condition. Conclusions: It is necessary to proceed with caution when observing abnormal morphological characteristics of the JB. Preoperative assessment of each case is essential for optimal outcomes.

The northernmost Polish Eemian palaeolake near Łęczyce − Stratigraphic and palaeoecological implications for a MIS 6a − MIS 5d sediment record

We report the results of high-resolution multi-proxy studies of a 10 m thick sedimentary profile from Łęczyce, Poland. It reveals a continuous lacustrine succession from the Eemian Interglacial. On this basis, we have distinguished seven sedimentary units (U7a-U7f) and ten local palynological zones (LPAZ Lec 1 − Lec 10), revealing the evolution of the lake from the moment of dead-ice melting, through the continuous filling of the lake basin with organic mud, to the final stage of shallowing and transformation into a peat bog. This northernmost known Eemian site was investigated for the first time, therefore, the reconstructed changes in local conditions were correlated with global changes from the final phase of the penultimate glaciation through the Eemian Interglacial to the beginning of the last glaciation. The results show that the melting of dead ice blocks at this site was delayed compared to central Poland, with lacustrine processes starting as glaciolimnic sedimentation. Furthermore, the delayed start of vegetation development around the lake resulted in the absence of a Pinus-Betula-Ulmus E2 level. During the Eemian, local conditions were generally stable, and sedimentation took place in a relatively deep basin with well-defined epilimnion and hypolimnion zones. Climatic instability at the end of the Eemian resulted in reduced vegetation cover. During the first climatic deterioration in the Weichselian (presumably the Herning Stadial), lacustrine sedimentation was reduced and the deposition of fine-grained mineral material predominated. This was followed by the complete drying out of the lake and the development of soil formation. The subsequent climatic warming (Brørup Interstadial?) recorded in the uppermost part of the profile (U7f) was characterised by the plant community Lec 10 (Carpinus-Corylus-Picea) and was presumably warmer than commonly assumed. Multi-proxy studies show that the development of the lake was more similar to that of southern Scandinavia than to that of Poland.

A new fusulinid species from the early Permian of northwestern Peninsular Malaysia: Evidence of the Artinskian warming event in the eastern Peri-Gondwanan Sibumasu Block

A new species of Crenulosepta, i.e., Crenulosepta perlisensis Vachard and Fassihi sp. nov., is described from a Cisuralian (Lower Permian) sandy limestones and calcareous sandstones in the Kubang Pasu Formation in northwestern Peninsular Malaysia, which forms part of the Peri-Gondwanan Sibumasu Block. Previous Malaysian authors reported the occurrence of Monodiexodina shiptoni and Monodiexodina sutschanica from the same area. The findings of this study provide a better overview of the Cisuralian fusulinid fauna found in this region. The presence of Crenulosepta confirms that the age of the uppermost part of the Kubang Pasu Formation is Artinskian, rather than extending into the Kungurian as previously recognized. The uppermost part of the Kubang Pasu Formation with its impoverished genus and species diversity is located just above the cold water brachiopods and diamictite beds. It indicates that during the Asselian (earliest Cisuralian), the northwestern Peninsular Malaysia was still part of the Gondwana continental shelf. During the late Early Permian, northwestern Peninsular Malaysia, as part of the eastern Cimmerian Continent, was located in a low latitude subtropical region of the paleo-equatorial tropical Tethyan Realm. The microfacies analysis of the Kubang Pasu Formation suggests a very high-energy, warm shallow marine environment of the inner ramp (e.g., sand shoals and banks).

2D and 3D numerical modelling for preliminary assessment of long-term deterioration in Irish glacial till geotechnical slopes

ABSTRACT Long-term geotechnical slope deterioration, influenced by weathering and meteorological factors, presents stability challenges to infrastructure. Wetting and drying cycles lead to pore water pressure variations, causing deformations and slope failure. Studies on glacial tills which investigate deterioration in geotechnical slopes focus on variables like pore water pressure, soil water retention, compaction, freeze–thaw cycles and cracking. This research conducts a preliminary assessment of an Irish glacial till-cut slope, establishing a data-driven foundation for long-term slope behaviour studies. Data analysis, geospatial modelling and numerical simulations were performed on a cut slope in Castleblayney (Ireland), considering short-term/undrained and long-term/drained conditions. FLAC/Slope and Scoops3D were used for 2D and 3D slope stability analyses, applying the First-Order Second Moment (FOSM) probabilistic approach to assess how minor soil property changes affect slope stability, including long-term deterioration scenarios. The study underscores the importance of precise instrument placement within Irish glacial till geotechnical cut slopes, particularly at the uppermost part where shallow and deep failures coincide under long-term and short-term scenarios. This informs strategic instrument positioning for accurate slope deterioration investigations. This research lays the groundwork for understanding mechanisms driving geotechnical slope deterioration and provides insights for future studies on geotechnical asset deterioration models in Irish glacial tills.

Depositional environments of Danian/Selandian of Kurkur Formation, Kurkur Oasis, south Western Desert, Egypt

In order to document the depositional environments of the Kurkur Formation in Southwestern Desert, Egypt, four surface sections measured in this region from north to south as follows: Gebel Garra, Wadi Abu-Sayal, Kurkur Oasis, and Sinn El-Kaddab. Planktonic foraminifera indicate that the age of Kurkur Formation in the study area is Danian to Selandian. Microfacies analysis shows graduation from wackestones, floatstones, and packstones in the lower part to oolitic and bioclastic grainstones in the upper section. The lower part of Kurkur Formation characterized by calcareous foraminifera assemblages, whereas arenaceous types are concentrated toward the uppermost part. Bivalves, gastropods, and echinoids are the most abundant macrofossils. Using the microfacies analyses and fossil content, the Kurkur Formation in the studied area deposited in middle neritic zone for the lower part, which is synchronous with the beginning of the Cenozoic transgression in the study area, and changed upward to inner neritic and supratidal environments.

The Lake Paravani archive – a contribution to the late Quaternary landscape evolution of the Lesser Caucasus (Georgia)

Lake Paravani, located on the volcanic Javakheti Plateau in the central part of the Lesser Caucasus at 2073 m a.s.l., forms a unique geo‐bio‐archive for palaeoenvironmental reconstructions in this remote region. Based on sediment cores from the southwestern part of the lake we expand the existing palynological and sedimentological records beyond the Last Glacial Maximum (LGM). For the first time, it is possible to reconstruct the palaeoenvironment in this part of the Lesser Caucasus back to c. 28 cal. ka BP. Our study shows that until 16 cal. ka BP glacial conditions dominated (Phase I) in the region; there is, however, proof that the lake already existed during the LGM. In the following transitional Phase II from 16 until 6 cal. ka BP, cold and arid conditions with sparse steppe vegetation and a lowered lake level prevailed. Around 10 cal. ka BP, tree pollen started to expand while herbaceous pollen, especially Chenopodiaceae, declined. In Phase III, since 6 cal. ka BP, mixed forest probably represented the Holocene climatic optimum. Fluctuating lake levels indicate shifting climatic conditions. The minor changes of arboreal pollen hin the uppermost part of Phase II may be an indication of human activity. The more humid, vegetation‐rich environment and mild climate around 4.5–2 cal. ka BP correlate with the expansion of the Late Bronze Age settlements in this area (from ~3.5 cal. ka BP/~1.5 ka BC). The proliferation of sites on the plateau, along with even higher‐altitude sites possibly dating to the same period, may indicate that this climate amelioration played an important role in enabling more sustained human occupation. The results extend the record on Lake Paravani by several millennia beyond the LGM and complement the palaeo‐lake reconstructions of the wider region, e.g. at Lake Van (Türkiye) or Lake Sevan (Armenia).

Ordovician-Silurian trace fossils from the Takche Formation, Parahio Valley, Spiti Himalaya, India: biostratigraphic and paleoenvironmental significance

ABSTRACT The Ordovician-Silurian trace fossils from the Takche Formation exposed near the Gechang locality, Parahio Valley, Spiti region, Himalaya are described. Following trace fossils were found in the Takche Formation: Arenicolites isp. Aulichnites parkerensis, Archaeonassa fossulata, Catenichnus isp. Cochlichnus isp. Cruziana furcifera, Cruziana goldfussi, Cruziana semiplicata, Chondrites targoni, Chondrites isp. A, Chondrites isp B, Helminthodoichnites isp. Lockeia siliquaria, Laevicyclus mongraensis, Planolites isp. Phycodes circinatus, Phycodes rarus, Phycodes isp. Treptichnus pedum, Thalassinoides isp. and Zoophycos isp. The lowermost part of the Takche Formation yielded significant traces of Cruziana affinity i.e. Cruziana furcifera, Cruziana goldfussi, and Cruziana semiplicata suggesting Tremadocian-Darriwilian age (Lower to Middle Ordovician). The middle part of the Takche Formation is dominated by Zoophycos isp. Chondrites targoni, Chondrites isp. A, and Chondrites isp. B suggests a deeper water offshore setting. The uppermost part yielded Archaeonassa fossulata, Aulichnites parkerensis, Laevicyclus mongraensis, Planolites isp. Helminthoidichnites isp. Phycodes rarus, Phycodes isp. and scratch marks. Overall, the trace fossil assemblages indicate a shallow marine shoreface to offshore depositional setting.