Classical Section Research Articles

Patterns of extinction and recovery across the Triassic–Jurassic boundary interval in three resilient Southern Tethyan carbonate platforms

During the end-Triassic extinction (ETE), carbonate platform biocalcifiers suffered high extinction rates that have been linked to volcanically-induced global changes in climate and carbon cycle. Most studies have been focused on the classical sections of the Northern Calcareous Alps (NCA, Austria) and Lombardy Basin (Italy), where the extinction of the aragonitic Dachstein-type biota (involutinid foraminifera and megalodontid bivalves) coincides with the demise of the carbonate platform and with the initial negative carbon isotope excursion (CIE) of the reference sections for the Triassic/Jurassic Boundary (TJB).In this study, we present a detailed facies analysis, bio- and carbon-isotope stratigraphy of three Southern Tethyan carbonate platform sections, Mt. Messapion (Greece), Valle Agricola and Mt. Sparagio (southern Italy) that instead show persisting carbonate productivity across the TJB and potentially preserve the most detailed record of timing and patterns of the ETE in these ecosystems.In the studied sections, the disappearance of the Dachstein-type biota is observed within a positive δ13Ccarb excursion that, according to our study, correlates with that documented in the Schattwald beds (NCA) and Malanotte Fm (Lombardy Basin) above the initial CIE. This level represents the true extinction of the Dachstein-type biota, while the disappearance in the Northern Tethyan sections of the NCA and Lombardy Basin represents a pseudoextinction coinciding with the carbonate platform demise. Above the ETE, Southern Tethyan carbonate platform sections are characterized either by microbial laminites or ooid and oncoid limestones and low-diversity associations.This study reveals a possible paleogeographic and/or latitudinal control on the response of biocalcifiers and carbonate platform ecosystems during the ETE. The Dachstein-type biota was resilient to the environmental perturbations associated with the initial CIE in Southern Tethys, but probably failed to survive subsequent and/or prolonged stress. Despite extinctions, Southern Tethyan carbonate platforms adapted to environmental disturbances through a shift of the dominant carbonate production style from aragonitic biocalcification to chemical and microbially-mediated CaCO3 precipitation. The ecosystem recovery was slow and aragonitic biocalcifiers (dasycladacean algae) reappeared during the early Sinemurian.

Study of motion stability of a viscoelastic rod

Stability of non-conservatively loaded elastic and inelastic bodies - a classic section of deformable solid mechanics that has been of interest for many years. In this paper, we study the motion stability of a free rod subjected to a constant tracking force on one of its ends. The defining ratio of the rod material is the Kelvin-Voigt model. The solution is presented in the form of an expansion in terms of beam functions. The number of terms of this expansion is substantiated. The values of the critical load in the presence and absence of viscosity are determined. The given analytical results are confirmed by numerical calculations.

Development of a Compact Phase Shifter for the Decimeter Wavelength Range

This paper presents the results of a study aimed at miniaturizing a microstrip phase shifter with switched transmission lines. Two compact phase shifters have been obtained — one in which the classic section of the transmission line is replaced by a low-pass filter, and the second in which the power supply filters are made on SMD elements. When comparing the theoretical and experimental characteristics of phase shifters, a discrepancy has been discovered between them, which is associated with the difference in the dielectric constant of the substrates in the model and the prototype, as well as due to differences in the values of lumped elements and tolerances in the manufacture of prototypes.

MODERN METHODOLOGICAL MEANS OF TEACHING GRAPHIC DISCIPLINES FOR FIRST-YEAR STUDENTS

In today's complex social conditions, significant changes are taking place in the system of domestic higher education. High-quality graphic training of graduates of higher educational institutions has been a pressing problem for many decades, so it is necessary to systematically update the existing methodological base and develop effective forms of training. As you know, drawing is the international language of architects and engineers. Working with flat images of spatial objects requires students to have developed spatial thinking already in the first year. In .this study, detailed attention is paid to the review and analysis of existing methodological approaches to the teaching of important classical sections of the discipline "Descriptive Geometry". The trends of improving teaching under the condition of distance learning are also considered, which helps future specialists of creative specialties to increase the level of individual competitiveness in modern market conditions. The purpose of the research is to determine and improve modern methodological tools for teaching graphic disciplines of students of the first course of creative specialties. Our study is related to the scientific research work "Improving the organization of the educational process using distance learning methods and teaching methods of graphic disciplines for students of construction and architectural and art specialties based on the competence approach", which is carried out on the basis of the Department of "Descriptive Geometry and Engineering Graphics" Odessa State Academy of Construction and Architecture (OSACEA) for many recent years. The work uses theoretical and empirical research methods: analysis, classification and synthesis of research base sources, many years of personal teaching experience; diagnostics of students specializing in 191 Architecture and Urban Planning and 023 Fine Arts (observations, monitoring the quality of teaching, self-analysis, etc.). Graphic competencies are very significant for a graduate’s future professional activity, which gives freedom in the creative implementation of the entire design process from the birth of an idea to its implementation.

New Insights into the Platform-to-basin Anatomy of the Urgonian Bas-Vivarais Domain (Lower Cretaceous; SE France)

This paper offers a new contribution to our ongoing harmonization efforts concerning the chronostratigraphic model of the southern France Urgonian-type carbonate platforms, which surrounded the Vocontian Basin during the Early Cretaceous. A multi-stratigraphic approach on the classical sections of the Ardèche River gorges and the Saint-Remèze Plateau have been used for reconstructing the evolution of the Bas-Vivarais Urgonian domain along an inner-to-outer platform profile; the latter being nearly perpendicular to the eastern Vocontian platform margin. In our transect, the installation and first developments of the Urgonian platform domain occured during the early Barremian Taveraidiscus hugii and Kotetishvilia nicklesi ammonite zones. This first platform stage was interrupted at a brief emersion episode that lasted through the Nicklesia pulchella ammonite zone, and resulted in the deposition of a sedimentary wedge with limited gradual downward, basinward shift in inner platform facies. This was followed by the regional deposition of shallow-water communities dominated by corals, echinoids, and orbitolinids, which passes basinward into open-marine, ammonite-bearing marly deposits in the Saint-Remèze Plateau outcrops. This change in facies was previously referred to as the Serre de Tourre Beds (STB), and dated to the Kotetishvilia compressissima and Moutoniceras moutonianum ammonite zones. The STB are further identified to as the local sedimentary expression of the Mid-Barremian Event recording a brief warming climate pulse testified by the presence of Offneria simplex, a caprinid rudist of Caribbean origin. Above, there is a regional recovery of inner platform Urgonian facies during the early late Barremian showing a striking progradational basinward trend. The latter, and its subsequent developments are in need of investigations. Taken together, the general evolution of the Urgonian Bas-Vivarais domain shows strong similarities with the sedimentary context of the nearby Subalpine Urgonian platform during the early Barremian. The finding of common sedimentary signals is more difficult with the Provence platform domain at that time.

Stratigraphy of the Albian–Cenomanian (Cretaceous) phosphorite interval in central Poland: a reappraisal

Several closely-spaced phosphorite beds stand out at the Albian–Cenomanian transition in the mid-Cretaceous transgressive succession at the northeastern margin of the Holy Cross Mountains, central Poland. They form a distinctive condensed interval of considerable stratigraphical, palaeontological, and economic value. Here, we correlate the classical section at Annopol with a recently investigated section at Chałupki. We propose a new stratigraphic interpretation of the phosphorite interval, based on lithological correlations, Rare Earth Elements and Yttrium (REE+Y) signatures of phosphorites, age-diagnostic macrofossils, and sequence stratigraphic patterns. This interval has long been considered as exclusively Albian in age. However, new macrofossil data allow us to assign the higher phosphorite levels at Annopol and Chałupki, which were the primary target for the phosphate mining, to the lower Cenomanian. In terms of sequence stratigraphy, the phosphorite interval encompasses the depositional sequence DS Al 8 and the Lowstand System Tract of the successive DS Al/Ce 1 sequence. The proposed correlation suggests that lowstand reworking during the Albian–Cenomanian boundary interval played an important role in concentrating the phosphatic clasts and nodules to exploitable stratiform accumulations. Our conclusions are pertinent to regional studies, assessments of natural resources (in view of the recent interest in REE content of the phosphorites), and dating of the fossil assemblages preserved in the phosphorite interval. On a broader scale, they add to our understanding of the formation of stratiform phosphorite deposits.

Frasnian reef mounds in the Durbuy–Bomal area (eastern border of the Dinant Synclinorium, Belgium)

This paper focuses on the Frasnian reefal development in the eastern border of the Dinant Synclinorium. Classical sections from the Durbuy–Bomal area were reevaluated for lithostratigraphy, microfacies, magnetic susceptibility (MS) and diagenesis. As regards the middle Frasnian succession, the studied area is located in a transitional zone between the Pont de la Folle/Philippeville Formations and the Moulin Liénaux/Grand Breux Formations. This succession is topped by Petit-Mont Member reef mounds. Massive mound microfacies are characteristic of the Petit-Mont and Lion Members, with fossil associations respectively dominated (from deepest to shallowest) by sponges; sponges, crinoids and corals; corals, crinoids, stromatoporoids and cyanobacteria; and microbes. Flank and off-mound microfacies consist of microbioclastic, bioclastic, crinoidal or lithoclastic bedded limestones. MS values are related to the depositional environment and regularly decrease from the off-mound to the reef mound microfacies. The reef mound diagenetic sequence is similar to that identified in other Petit-Mont buildups: cementation in the marine phreatic zone preliminary to drowning, then the development of a meteoric lens at the time of a marine regression, with dysoxic facies in the distal zones of the aquifer and, finally burial cementation and dolomitization during the Variscan tectonism.

PROFESOR VALERIAN MYKOLAYOVYCH WEBER — OUTSTANDING GEOLOGIST-SURVEYER AND EXPERT IN TRILOBITES (to the 150th Аnniversary of his birth)

Valerian Мykolayovych Weber (1871—1940) entered the history of geological science of the former USSR and the world as an outstanding geologist-surveyor, a prominent paleontologist, a specialist in trilobite fauna and Paleozoic stratigraphy, a teacher and organizer of science, an active member of scientific geological societies. He was the discoverer of a number of deposits of iron and copper-arsenic-lead ores, coal, and oil. The scientist studied the classical sections and fauna of the Paleozoic of Western Europe, carried out geological surveys in sultry Turkestan. As a geologist, Valerian Mykolayovych traveled and studied regions of Central Asia, Urals, Crimea, Caucasus, Pamirs, Novaya Zemlya, Svalbard, the Timan Ridge and the Far East. Of particular importance for him were the unique Paleozoic sections of the Donetsk folded structure. The scientist is the author of the monographs “Field Geology”, “Mineral Resources of Turkestan” and the geology of the Cheleken Peninsula, he is also known as a seismologist — he studied the Andijan, Akhalkalaki and Shemakha earthquakes. However, paleontological studies of trilobites brought world fame to the scientist. In total, for Permian, Devonian, Ordovician, and Silurian trilobites, V.M. Weber wrote six original monographs and more than ten articles. The first large monograph by V.M. Weber was the book “Trilobites of Turkestan”, then “Trilobites of Donbass” and a series of consolidated monographs on the Carboniferous trilobites of the USSR. The monograph by V.M. Weber “Trilobites of Donbass” contains material on trilobites collected by scientists from continuous, “reference” sections of marine carboniferous deposits of the Donets Basin. Paleontological works by V.M. Weber cover a wide range of geological time — from the Ordovician to the Permian inclusive. They are important for the stratigraphy of the sedimentary strata of the Carboniferous Donbas of Central Asia, Urals, Caucasus, Crimea and other geological regions of the USSR.

A Forgivable Enthusiasm

A Forgivable Enthusiasm

Musculotendinous system of mesopelagic fishes: Stomiiformes (Teleostei).

Every night the greatest migration on Earth starts in the deep pelagic oceans where organisms move up to the meso- and epipelagic to find food and return to the deeper zones during the day. One of the dominant fish taxa undertaking vertical migrations are the dragonfishes (Stomiiformes). However, the functional aspects of locomotion and the architecture of the musculotendinous system (MTS) in these fishes have never been examined. In general, the MTS is organized in segmented blocks of specific three-dimensional 'W-shaped' foldings, the myomeres, separated by thin sheets of connective tissue, the myosepta. Within a myoseptum characteristic intermuscular bones or tendons may be developed. Together with the fins, the MTS forms the functional unit for locomotion in fishes. For this study, microdissections of cleared and double stained specimens of seven stomiiform species (Astronesthes sp., Chauliodus sloani, Malacosteus australis, Eustomias simplex, Polymetme sp., Sigmops elongatus, Argyropelecus affinis) were conducted to investigate their MTS. Soft tissue was investigated non-invasively in E. schmidti using a micro-CT scan of one specimen stained with iodine. Additionally, classical histological serial sections were consulted. The investigated stomiiforms are characterized by the absence of anterior cones in the anteriormost myosepta. These cones are developed in myosepta at the level of the dorsal fin and elongate gradually in more posterior myosepta. In all but one investigated stomiiform taxon the horizontal septum is reduced. The amount of connective tissue in the myosepta is very low anteriorly, but increases gradually with body length. Red musculature overlies laterally the white musculature and exhibits strong tendons in each myomere within the muscle bundles dorsal and ventral to the horizontal midline. The amount of red musculature increases immensely towards the caudal fin. The elongated lateral tendons of the posterior body segments attach in a highly complex pattern on the caudal-fin rays, which indicates that the posterior most myosepta are equipped for a multisegmental force transmission towards the caudal fin. This unique anatomical condition might be essential for steady swimming during diel vertical migrations, when prey is rarely available.

IMPLEMENTATION OF THE ADVANCED LEARNING IN THE PROCESS OF FUNDAMENTAL MATHEMATICAL TRAINING OF BACHELORS IN THE FIELD OF ELECTRONICS AND TELECOMMUNICATION

The article substantiates the expediency of the implementation of the advanced learning in the process of fundamental mathematical training of bachelors in the field of electronics and telecommunications. At the moment, the field requires mandatory (deep) knowledge of the main classical sections of mathematics, it is also important to acquaint students in higher mathematics with elements of modern mathematical theories, concepts that allow learners to better understand special courses in mathematics and relevant special disciplines. materials of mathematics, which are used in the modern mathematical models of technical developments. The aim of the article is to reveal the approaches to the concept of the advanced learning in the process of fundamental mathematical training of future bachelors in the field of electronics and telecommunications.The main methods that were implemented in the study of the problem of advanced learning were the analysis and synthesis of the scientific sources on the selected problem, observation, implementation of projects and evaluation of their results.
 It is offered (from the first semester) to introduce generalized concepts (norm, operator, etc.) in time, to acquaint with ideas of variational calculus, functional analysis, mathematical methods of research of linear equations with variable coefficients, theory of stochastic approximation, mathematical modelling. Then the future specialist will be able to comprehend the objects, which have been already developed by mathematicians but have not been used yet. Thus, a difficult topic or concept can be considered in advance in some connection with the currently studied material. For example, during the study of a function and the construction of its graph, along with the asymptote, students can be introduced to the approximation of the function, the concepts of interpolation and approximation. It is expedient to acquaint students with these problems more deeply during performance of independent tasks (consultations, the abstract, the report at conference, etc.).

Heroic pastoral and its national-style reception IN THE CANTATA “YELLOW RIVER” BY XIAN XINGHAI

Heroic pastoral and its national-style reception IN THE CANTATA “YELLOW RIVER” BY XIAN XINGHAI

A high-resolution computed tomography based scoring system to predict ease of electrode insertion in cochlear implantation.

This study aimed to formulate a scoring system based on high-resolution computed tomography scans to predict ease of electrode insertion during cochlear implantation via posterior tympanotomy in paediatric patients. A scoring system Cochlear Implantation Radiological Assessment Score (CIRAS) was formulated based on six parameters. This score was correlated with intra-operative findings, and receiver operating characteristic analysis was performed to determine the optimal cut-off score to predict difficulty of surgery and to establish the inherent validity of the scoring system by area under curve. Receiver operating characteristic analysis showed that optimal cut-off score was 8 (93.1 per cent specificity and 56.52 per cent sensitivity), and area under the curve was 0.828. Patients with CIRAS of more than 8 had significantly higher time for surgery (p < 0.05). CIRAS is an easy to administer tool by utilising classical axial and coronal sections, without any numerical measures. Pre-operative assessment by this score gives a good idea of intra-operative challenges.

Early Crioceratites (heteromorphic ammonites) from the lower Hauterivian of south-eastern France: systematics, intraspecific variation and biostratigraphic implications

Two acmes of the genus Crioceratites were recorded in the current Crioceratites loryi Zone (lower Hauterivian) in the Lower Cretaceous series of south-eastern France (Vocontian Basin), both in the classic section of the Cheiron ravine (Castellane area) and in the Hauterivian GSSP area at La Charce. The revision of an abundant material allows us to define Crioceratites claveli sp. nov. The first acme and the first part of the second acme correspond to the range of C. claveli sp. nov. and not to C. loryi as previously admitted. The remaining of the second acme is related to this latter species solely. The great abundance of C. claveli sp. nov. in the lower interval Horizon allowed a detailed analysis of its variation around 3 factors: (1) dimorphism; (2) multipolar variation of order two here characterized by an absence of correlation between the ornamental and morphological shell parameters (non-covariant factors); and (3) ontogenic heterochronies, which depend on the robustness of the ornamentation only. On the other hand, the northern edge of the Provençal platform delivered C. jurensis (revised here) from the top part of the Acanthodiscus radiatus Zone, which reduces the gap with the older Crioceratites known in the uppermost Valanginian. Finally, the study of the stratigraphic distribution of C. claveli sp. nov. and C. loryi leads to propose the new C. claveli (Sub)Zone instead of the C. loryi (Sub)Zone. This proposal for the south-eastern France may have extension potential for the Mediterranean Province of the Mediterranean Caucasian Subrealm (Tethyan Realm).

Terreneuvian bio- and chemostratigraphy of the South Sichuan Region (South China)

Classical sections, such as the Maidiping and Daqiao Mine sections of South Sichuan (China), expose early Cambrian deposits that are crucial for understanding the biological and environmental evolution of Yangtze Craton. These sequences are rich in Terreneuvian small shelly fossils, which can be assigned to assemblages I and III from South China. The Anabarites trisulcatus – Protohertzina anabarica Assemblage Zone (Assemblage I) is recognized at the lower Maidiping Formation. The second assemblage ( Paragloborilus subglobosus – Purella squamulosa Assemblage Zone) cannot be verified in South Sichuan, although previous reports claimed its existence based on the occurrence of Paragloborilus subglobosus . The third assemblage ( Watsonella crosbyi Assemblage Zone) is confirmed in the upper Maidiping Formation. The abundant bioclasts in this interval indicate abrasions and bioerosions by winnowing or starved sedimentation. Carbon isotope values from the Maidiping section present no negative excursion at the presumed Ediacaran–Cambrian transition. A positive carbon isotope excursion is observed in the Upper Maidiping Formation (Assemblage III) which is correlated to the ZHUCE excursion in the Dahai Member of eastern Yunnan. The shallow-water deposits of South Sichuan can be correlated with the South China, western Mongolia and Siberia successions based on biozonations and carbon isotope trends. Supplementary material: Isotope data are available at https://doi.org/10.6084/m9.figshare.c.5326834 Thematic collection: This article is part of the Advances in the Cambrian Explosion collection available at: https://www.lyellcollection.org/cc/advances-cambrian-explosion

A theatrical double-faced mask preserved at the Museum of Lipari (Messina): study and 3D reconstruction through portable equipment

&lt;p class="VARKeywords"&gt;The new tools for 3D survey and modelling (as portable scanners and software packages), often in combination with diagnostics, are nowadays able to provide indispensable elements for the study of archaeological artefacts; their applications to museum’s heritage can be also useful to integrate the traditional graphic documentation and contribute to enhancement and dissemination. This paper shows the benefit of using the aforementioned tools to study the peculiar clay mask No. 11114-E, discovered in 1973 in the Greek necropolis of Lipára, inside tomb No. 1558. The specimen, now exhibited in the Classical Section of the Aeolian Museum, is considered unique both in the Aeolian Islands and in the ancient Greek world, as it is the only one merging two half faces attributable to different characters. This feature, unknown at the time of discovery, has been highlighted in 2018, thanks to a restoration intervention by which a hard concretion layer covering a large portion of the mask surface was removed, bringing to light a smiling young half-face next to an old one with Silenic features. In 2019, the mask was surveyed in situ through a portable and performing laser-scanner arm (the QuantumTM FaroArm by FARO) to produce a high-resolution 3D model useful to enhance the reading of the two halves (not evident enough, due to its state of preservation). The data processing was performed using the Geomagic Wrap software, able to align and merge multiple scans into a single model and to export results in multiple formats, easily shareable and viewable in free software or via the web. Finally, thanks to this method, the successful generation of a digital replica was performed; the resulting replica is useful for dissemination and as a support for the hypothetical reconstruction of the two prototypes taken as models by the craftsman who created the mask.&lt;/p&gt;&lt;p&gt;&lt;strong&gt;Highlights:&lt;/strong&gt;&lt;/p&gt;&lt;ul&gt;&lt;li&gt;&lt;p&gt;A 'mobile laboratory’ consisting of portable equipment has been set up to perform 3D metric surveys on a selection of artefacts preserved at the Museum of Lipari.&lt;/p&gt;&lt;/li&gt;&lt;li&gt;&lt;p&gt;By means of an ultra-precision laser-scanner arm, a 3D survey on a miniaturistic double-faced mask, belonging to the classical theatrical terracotta, has been performed.&lt;/p&gt;&lt;/li&gt;&lt;li&gt;&lt;p&gt;A geometrically accurate and realistic 3D final model has been created. This helped the study and reconstruction of the two characters composing the mask.&lt;/p&gt;&lt;/li&gt;&lt;/ul&gt;

Разработка концепции подготовки кадров для геопространственной индустрии в рамках сквозных технологий цифровой экономики

The article describes the difficulties of training personnel for a dynamically developing geospatial industry (geoindustry). The authors analyzed the current state of the geoindustry based on scientific publications, industry reports, opinions of workers and industry leaders, highlighted its key technological elements, such as geographic information systems, remote sensing of the Earth, including laser scanning technologies and survey from UAVs, GNSS- and BIM technologies, sensor systems. It is noted that technological changes entail the transformation of the classical sections of cartography, which include thematic mapping. Consequently, it is necessary to improve the scientific and methodological foundations for a number of sections of cartography and to update the strategy of educational activities in the field of cartography and geoinformatics. New elements in the work of a specialist in the field of cartography and geoinformatics, associated with the use of geosciences, functions of geostatistics, artificial intelligence technologies, which appeared as a result of a significant increase in the volume and variety of available spatial and nonspatial data are highlighted. Based on the analysis of the ongoing technological changes, tasks that must be solved by specialists in the geospatial industry are formulated, a conclusion about the need for educational programs to correspond to the technological level of the geoindustry is drawn. The concept of education for the geospatial industry is proposed, which includes the development of professional standards, as well as bachelor and master programs. The experience of participation in the development of the professional standard “Specialist in cartography and geoinformatics” is presented. The elements of the developed educational programs for bachelor degree 05.03.03 “Cartography and geoinformatics” and master’s degree 05.04.03 “Cartography and geoinformatics” are presented, a list of professional competencies and logical structure of blocks of disciplines are presented.

Validation and real-life demonstration of ETCS hybrid level 3 principles using a formal B model

In this article, we present a concrete realisation of the ETCS hybrid level 3 concept, whose practical viability was evaluated in a field demonstration in 2017. Hybrid level 3 introduces virtual subsections as sub-divisions of classical track sections with trackside train detection. Our approach introduces an add-on for the radio block centre (RBC) of Thales, called virtual block function (VBF), which computes the occupation states of the virtual subsections using the train position reports, train integrity information, and the track occupation states. From the perspective of the RBC, the VBF behaves as an interlocking that transmits all signal aspects for virtual signals introduced for each virtual subsection to the RBC. We report on the development of the VBF, implemented as a formal B model executed at runtime using ProB and successfully used in a field demonstration to control real trains.

To the history of the Baltic-Ladoga connection

In accordance with geochronological, lithological, palaeocriological and geomor phological data from the new key section on the right bank of the Neva River (the center of the hypothetical Mga-Tosna watershed) and the well-known classical section on the Nevsky Pyatachok, it was established that the flow from Lake Ladoga to the Baltic Sea in the southern part of the Karelian Isthmus at the site of the modern Neva Lowland took place in the Late Glacial time somewhat earlier than 11980 cal yr. BP. After that, the flow along the (pre-) Neva has not been completely interrupted to date, and the transgressions of the Baltic palaeobasins has not penetrated into the territory of the Neva Lowland. There was probably a bifurcation of the flow from the Ladoga along the (pre-) Neva and the Heinijoki Strait in the central part of the Karelian Isthmus in the Late Pleistocene and the Early Holocene.

Change from rimmed to ramp platform forced by regional and global events in the Cretaceous of the Friuli-Adriatic Platform (Southern Alps, Italy)

Carbonate platforms are sedimentary archives recording the evolution of the global carbon cycle. Their stratigraphic architecture depends on the regional tectonics, controlling subsidence rates and geometries, as well as the paleoceanography and evolutionary trends, controlling the different organisms thriving at their margins, such as frame-building corals or mound-building microbes. We present an integrated bio- and chemostratigraphic study of the Aptian to Santonian interval of a base-of-slope section located in the Southern Alps of northeastern Italy that we correlate with the classic section representing the Friuli-Adriatic Carbonate Platform, one of the largest isolated platforms of the low latitude Tethys. We show the effects of the end of the passive-margin stage and the interaction between foreland flexuring due to the growing Alps, to which the study area represented the retroforeland, and the approaching prowedge of the Dinarides. The Friuli-Adriatic platform margin shows an abrupt change from reef rimmed to ramp, where abundant microbial mounds provided the habitat for the rudists to thrive. This change occurred around the late Albian and likely correlates with the Oceanic Anoxic Event (OAE) 1d. The previous OAE's did not change the structure of this platform, whose margins were mostly rigid and colonized by corals and calcareous sponges. Late Albian was a time of important changes in paleoceanography in Tethys and North Atlantic Oceans. We propose that the paleooceanographic changes related to the OAE- 1d had more profound impacts on the Friuli-Adriatic Platform than the previous Cretaceous OAE's since they co-occurred with the tectonic transition from passive margin to foreland ramp. The increased subsidence rates, in conjuction with the important late Albian paleoceanographic changes, created favourable conditions for a dramatic change in the platform margin physiography and ecology.