Structural Interpretation Research Articles

An Application of 3D Cross-Well Elastic Reverse Time Migration Imaging Based on the Multi-Wave and Multi-Component Technique in Coastal Engineering Exploration

Precise surveys are indispensable in coastal engineering projects. The extensive presence of sand in the coastal area leads to significant attenuation of seismic waves within unsaturated loose sediments. As a result, it becomes challenging for seismic waves to penetrate the weathered zone and reach the desired depth with significant amount of energy. In this study, the application of three-dimensional (3D) cross-well elastic reverse time migration (RTM) imaging based on multi-wave and multi-component techniques in coastal engineering exploration is explored. Accurate decomposition of vector compressional (P) and shear (S) waves is achieved through two wavefield decoupling algorithms without any amplitude and phase distortion. Additionally, compressional wave pressure components are obtained, which facilitates subsequent independent imaging. This study discusses and analyzes the imaging results of four imaging strategies under cross-correlation imaging conditions in RTM imaging. The analysis leads to the conclusion that scalarizing vector wavefields imaging yields superior imaging of P- and S-waves. Furthermore, the imaging results obtained through this approach are of great physical significance. In order to validate the efficacy of this method in 3D geological structure imaging in coastal areas, RTM imaging experiments were performed on two representative models. The results indicate that the proposed 3D elastic wave imaging method effectively generates accurate 3D cross-well imaging of P- and S-waves. This method utilizes the multi-wave and multi-component elastic wave RTM imaging technique to effectively leverage the Earth’s elastic medium without increasing costs. It provides valuable information about the distribution of subsurface rock layers, interfaces, and other structures in coastal engineering projects. Importantly, this can be achieved without resorting to extensive excavation or drilling operations. This method addresses the limitations of current cross-well imaging techniques, thereby providing abundant and accurate geological and geophysical information for the analysis and interpretation of 3D geological structures in coastal engineering projects. It has important theoretical and practical significance in real-world production, as well as for the study of geological structures in coastal engineering.

Cinematic Rendering of Pancreatic Neuroendocrine Tumours: Opportunities for Clinical Implementation: Part 2: Preoperative Planning and Evaluation of Metastatic Disease.

Pancreatic neuroendocrine tumours (PNETs) are a rare subset of pancreatic tumours that have historically comprised up to 3% of all clinically detected pancreatic tumours. In recent decades, however, advancements in imaging have led to an increased incidental detection rate of PNETs and imaging has played an increasingly central role in the initial diagnostics and surgical planning of these tumours. Cinematic rendering (CR) is a 3D post-processing technique that generates highly photorealistic images through more realistically modelling the path of photons through the imaged volume. This allows for more comprehensive visualization, description, and interpretation of anatomical structures. In this 2-part review article, we present the first description of the various CR appearances of PNETs in the reported literature while providing commentary on the unique clinical opportunities afforded by the adjunctive utilization of CR in the workup of these rare tumours. This second instalment focuses on the applications of CR in optimizing preoperative planning of PNETs.

Structural and seismic attribute analysis of the Paleocene carbonate reservoir from the Balkassar Field, Potwar Plateau, Pakistan

The structural and seismic properties of the Paleocene carbonate reservoir are re-evaluated, using 3D seismic data multi-attributes, to improve reservoir prediction accuracy rarely documented earlier. This study highlights a number of relevant post-stack seismic attributes for understanding the structural setup and seismic properties of a carbonate reservoir. The structural analysis was carried out using seismic interpretation, combined with multi-attribute analysis for prospect actualization and generation of a 3D structural model to determine the structural aspect. The structural interpretation reveals the presence of faults and an asymmetrical anticlinal structure demonstrating a four-way closure, confirming compressional tectonics. The high amplitude anomaly (-6 to 12) combined with the RMS attribute (23 to 32) suggests bright spots in the Paleocene carbonate reservoir and gas saturated zone, the variance attribute (0.05 to 0.03) highlights the presence of two major faults, and the lower instantaneous frequency demonstrates the presence of hydrocarbons. The attribute results indicate that the Lockhart Limestone possesses good reservoir potential as revealed by DHI (bright spot), gas saturated zone and a trapping mechanism supported by four-way structure closure in the region and can help to understand analogous carbonate reservoirs in similar geological settings around the world.

Cinematic Rendering of Pancreatic Neuroendocrine Tumours: Opportunities for Clinical Implementation: Part 1: Tumour Detection and Characterization.

Pancreatic neuroendocrine tumours (PNETs) are a rare subset of pancreatic tumours that have historically comprised up to 3% of all clinically detected pancreatic tumours. In recent decades, however, advancements in imaging have led to an increased incidental detection rate of PNETs and imaging has played an increasingly central role in the initial diagnostics and surgical planning of these tumours. Cinematic rendering (CR) is a 3D post-processing technique that generates highly photorealistic images through more realistically modelling the path of photons through the imaged volume. This allows for more comprehensive visualization, description, and interpretation of anatomical structures. In this 2-part review article, we present the first description of the various CR appearances of PNETs in the reported literature while providing commentary on the unique clinical opportunities afforded by the adjunctive utilization of CR in the workup of these rare tumours. The first of these 2 instalments highlights the utility of CR in optimizing PNET detection and characterization.

Structural elucidation and interpretation of 2D‒3D supramolecular assemblies featuring lone-pair···π interaction in two Cu(II)‒PDA complexes: Experimental and computational assessment

The structural study of two synthesized Cu-PDA (Cu = Copper(II), PDA = deprotonated Pyridine-2,6-dicarboxylic acid) complexes has been carried out using single-crystal X-ray diffraction where complex (1) [Cu(PDA)(H2O)2] exhibits one-dimensional (1D) and two-dimensional (2D) supramolecular assemblies and complex (2) [Cu(PDA)(H2PDA)]·H2O exhibits 1D, 2D, and 3D (three-dimensional) supramolecular networks in their solid-state structure with the aid of intermolecular noncovalent interactions. Lone pair···π/π···lone pair networks are exclusively found in both complex (1) and (2). The intermolecular interactions are characterized through Hirshfeld surface analysis and quantified by 2D fingerprint plot. The noncovalent interactions are further characterized by Bader's theory of ‘Atoms in Molecules’ (AIM) and ‘noncovalent interaction’ (NCI) plot and the topological parameters at bond critical points (BCPs) have been evaluated. Therefore, the energetic factors to the stabilization of the crystal structure observed experimentally have been obtained by the computational calculations.

Contrast arthrography of the equine temporomandibular joint.

Disorders of the equine temporomandibular joint (TMJ) cause clinical problems and detailed investigations of this joint are becoming more common. Specialist radiographic projections have the potential to highlight osseous abnormalities; however, the ability to assess the intra-articular soft tissue structures is currently limited to computed tomography (with, or without contrast enhancement) or magnetic resonance imaging. Both modalities are expensive and not readily accessible. To develop a technique of contrast arthrography of both compartments of the equine TMJ in cadavers and then perform the refined technique in three living horses as a proof-of-principle. A descriptive, experimental, study. Contrast arthrography of the discomandibular and discotemporal joint compartments of both TMJs was performed in 12 cadaveric equine heads using needles placed in the caudal pouches of the respective joint compartments. Radiographs were taken using previously published techniques, repeated with the mouth open and after air had been injected into the joints, to perform a double-contrast study. The TMJs of three healthy horses were subsequently examined to determine the validity of the procedure in live animals. Single and double-contrast arthrography allowed delineation of the dorsal and ventral surfaces of the intra-articular disc in addition to filling the rostral and caudal joint pouches of the independent joint compartments. Contrast extravasation was common, and in two instances iatrogenic disc penetration resulted in the false diagnosis of pathologic disc perforation. The techniques were well tolerated in all three live horses. Low number of horses. Contrast arthrography allows interpretation of intra-articular soft tissue structures, but caution is advised in diagnosing intra-articular disc perforation. Even with experience, accessing the discomandibular joint can be challenging.

Pleistocene deformation of the Malargüe fold–thrust belt from structural modelling and geochronology of syntectonic sedimentation

We report uplift and shortening rates from a late Neogene–Pleistocene deformation stage of the frontal fold–thrust belt and adjacent wedge-top in the Principal Cordillera of the southern Central Andes (latitude 33–39°S). A structural model is presented based on integration of surface field data and subsurface 2D seismic sections. Shortening, uplift and sedimentation rates were calculated from different steps of kinematic modelling. Our structural interpretations and modelling are integrated with new detrital zircon U–Pb geochronology to define a previously overlooked Pleistocene period of orogenic shortening and syntectonic sedimentation in the Malargüe basin. This task was possible as a result of the dating of three samples yielding ages between ∼12 and 1 Ma obtained from a 900 m deep well located in the foreland. From stratigraphic correlations, our data record an active Plio-Pleistocene wedge-top depozone coeval with retreat of the volcanism, and the emplacement of retroarc basalts. Structural modelling, together with detrital zircon U–Pb provenance data, registers shortening producing a foredeep to wedge-top Plio-Pleistocene transition, adjusting and completing the knowledge of the frontal fold–thrust belt and foreland basin in the southern Central Andes. Supplementary material: Supplementary tables are available at https://doi.org/10.6084/m9.figshare.c.7033425

Detailed seismic structure beneath the earthquake zone of Yogyakarta 2006 (Mw ∼6.4), Indonesia, from local earthquake tomography

The earthquake, which occurred in Yogyakarta, Indonesia, on May 26, 2006, at 22:53:58 UTC with Mw ∼6.4, was one of the most destructive earthquakes in Indonesia. The earthquake caused thousands of fatalities, tens of thousands of injuries, and hundreds of thousands of house damages in the Yogyakarta area and its surroundings at a loss of billions of dollars. Previous studies from seismic tomography and satellite radar imaging hypothesized that the earthquake was caused by activating a so far unknown fault east of the Opak Fault. Although, in the beginning, the Opak fault was suspected to be the source of the Yogyakarta earthquake in 2006. This assumption was made because the damage was maximum in the Bantul area west of the Opak Fault. This study demonstrates that our seismic tomography achieved a higher resolution than the previous study and could resolve a failed complex fault system. We utilized more aftershocks (2170 events) and smaller grid sizes for seismic tomography inversion. Four focal mechanisms from aftershocks for Mw ≥ 4.5 were also conducted to support structure interpretation in the study area. Our results successfully delineate the Opak Fault and the second fault, namely the Ngalang Fault, parallel to the eastern part of the fault at a depth of 9 km. Two faults could be indicated by the velocity contrast of Vp, Vp/Vs ratio, and Vs from a horizontal section tomogram. Our focal mechanisms also support seismic tomography, revealing two fault planes in our study area. The results show that the two faults are connected by the Oyo Fault, which is ruptured in the opposite direction compared to the two faults.

Mesozoic structural evolution of the Northern South China Sea margin using potential field modelling

This study conducts a comprehensive geophysical inspection of the Northern South China Sea Margin (NSCSM), a complex and pivotal area for unraveling the tectonic history of Southeast China. We employ structural interpretation of the gravity and magnetic data by applying processing techniques and 2D forward modelling to delineate and subdivide the primary subsurface structures, and also to identify the sedimentary basins. Our findings reveal that the NSCSM exhibits a succession of extensional forearc basins above a heterogeneous basement, including a Mesozoic Andean-type magmatic arc and a Western Pacific-type marginal oceanic basin. It has substantial variations in crustal densities and susceptibilities across the NSCSM, reflecting its intricate geological history. The integrated interpretation of this study highlights the substantial impact of the Indosinian and Yanshanian thrusting and orogenies. These geological processes have played a significant role in deformation partitioning, leading to the development of elongated troughs and basins intersected by numerous prominent structures trending in the NE, ENE, and EW directions. The Indosinian faults provide insights into the boundary between these structures, which formed due to the Dian-Qiong Suture and the Paleo-Pacific Plate subduction. These tectonic processes have major structural trends, particularly impacting the offshore forearc region in the NE and EW directions, characterized by deep basins overlying thin crust. Our study also identifies multiple minor trends, including horse-tails and secondary fault systems of the Yanshanian origin, which inherited from the regional tectonics. These trends suggest that post-orogenic stresses and shearing have played a role in rotational and ridge jump processes during the opening and closing phases of the South China Sea (SCS). Furthermore, an uneven relationship exists between the calculated magnetic anomaly and the thickness of Cenozoic sediments, with a significant increase in sediment depth observed in the southern NSCSM compared to both crustal thickness and its heterogeneity.

On seismic gradiometric wave equation inversion for density

SUMMARY Material density remains poorly constrained in seismic imaging problems, yet knowledge of density would provide important insight into physical material properties for the interpretation of subsurface structures. We test the sensitivity to subsurface density contrasts of spatial and temporal gradients of seismic ambient noise wavefields, using wave equation inversion (WEI), a form of seismic gradiometry. Synthetic results for 3-D acoustic media suggest that it is possible to estimate relative density structure with WEI by using a full acoustic formulation for wave propagation and gradiometry. We show that imposing a constant density assumption on the medium can be detrimental to subsurface seismic velocity images. By contrast, the full acoustic formulation allows us to estimate density as an additional material parameter, as well as to improve phase velocity estimates. In 3-D elastic media, severe approximations in the governing wave physics are necessary in order to invert for density using only an array of receivers on the Earth's free surface. It is then not straightforward to isolate the comparatively weak density signal from the influence of phase velocity using gradiometric WEI. However, by using receivers both at the surface and in the shallow subsurface we show that it is possible to estimate density using fully elastic volumetric WEI.

Tunable resource allocation dynamics for interpreting economic complexity

A lot of effort has been devoted to network structural interpretations of the economic complexity which can affect the level of economic growth and the activities of economic entities, although it remains unknown how network dynamical interpretations on which the economic complexity index operates affects its performance. Here, we regard export trade flows as the dynamics of resource allocation, and design a tunable resource allocation (TRA) process for interpreting economic complexity. The TRA could degrade into the classical economic complexity index (ECI) when the tunable parameter equals zero. We apply the TRA dynamics to the perfectly nested triangular matrix and the real country-product bipartite network from the world trade data to interpret economic complexity respectively. The parametric interpretations provide conceptual descriptions of the economic complexity index, shedding new light on a pattern of specialization of resource allocation, and the fluctuation of the economic complexity in countries and products. Moreover, the relationship of economic complexity between countries and products in the framework of TRA reveals that higher-ECI countries usually specialize in higher-ECI products while products not so as to countries, and the correlation strength varies with tunable parameters.

Construction of knowledge constraints: a case study of 3D structural modeling

The uncertainty of structural interpretation complicates the practical production and application of data-driven complex geological structure modeling technology. Intelligent structural modeling excavates and extracts structural knowledge from structural interpretation through human–machine collaboration and combines structural interpretation to form a new model of complex structural modeling guided by knowledge. Specifically, we focus on utilizing knowledge rule reasoning technology to extract topological semantic knowledge from interpretive data and employ knowledge inference to derive structural constraint information from complex geological structure models, thus effectively constraining the 3D geological structure modeling process. To achieve this, we develop a rule-based knowledge inference system that derives theoretical models consistent with expert cognition from interpretive data and prior knowledge. Additionally, we represent the extracted knowledge as a topological semantic knowledge graph, which facilitates computer recognition and allows estimation of intersection lines during 3D geological modeling, resulting in the creation of accurate models. The applicability of our proposed method to various complex geological structures is validated through application tests using real-world data. Furthermore, our method effectively supports the realization of intelligent structure modeling in real working area.

Domain adaptation-based sparse time-frequency analysis and its application on seismic attenuation estimation

Time-frequency (TF) transform is a commonly used tool for geologic structure interpretation and attenuation estimation, mainly including the linear and nonlinear methods. The former consists of short-time Fourier transform, continuous wavelet transform, S-transform, etc., which can be efficiently implemented. However, they suffer from the Gabor uncertainty principle, which limits their TF readability. The latter can effectively enhance TF readability; nevertheless, it has several unavoidable drawbacks, such as low computational efficiency and parameter selection. For seismic sparse TF (STF) analysis (STFA), we develop a domain adaptation-based STFA (DASTFA) model. This model mainly contains two steps. First, we suggest an STF network (STFNet) for mapping a 1D seismic signal to a 2D STF spectrum, which is pretrained using synthetic traces and STF labels. Second, based on the pretrained STFNet, we design a DASTFA model for transferring to field data. Note that the synthetic traces are generated using well-log data and horizon at the study area, located in the Ordos Basin, China, which can reduce the gap between synthetic and field data. Afterward, we use synthetic traces with their STF labels for model pretraining in the first step and field data without STF labels for model transferring in the second step. Here, model transferring indicates transferring the pretrained model parameters based on field traces. Finally, to test the validity and effectiveness of DASTFA, we apply it to synthetic and field data. Moreover, we test the availability of seismic attenuation estimation by adopting the suggested model for 3D poststack field data volume, which achieved encouraging results.

Structural control on carbon emissions at the Nirano mud volcanoes – Italy

The Nirano Salse in Italy is a well-studied site where natural gas seepage (NGS) and other hydrocarbon fluids and gases are emitted at the earth's surface. A novel integrated approach is applied to define a comprehensive structural interpretation of the gas seepage and flow dynamic in the mud volcano system of the Nirano Salse Regional Nature Reserve (Modena, Northern Apennines). The paper investigates the relationship between gas emissions and local structures, particularly faults and fractures, in the shallow subsurface (down to 500–600 m depth) to understand the control that structures have on fluid ascent from deep leaky hydrocarbon traps. We performed continuous monitoring of mud levels within vents; carried out geological surveys to characterize the main stratigraphic and structural discontinuities; measured the carbon emissions (CH4 and CO2) seepage both from volcanoes and the surrounding soil by a portable gas fluxmeter; and integrated the results with available geophysical surveys. The authors argue that the transgressive Pleistocene-Pliocene Argille Azzurre Formation hides the complex and highly structured pre-Pliocene geology of the area, in which faults and fractures act as pathways for deep fluid ascent. The emissions are aligned along a NE-SW trend at the intersection of a NE-SW fracture system and NW-SE-oriented normal faults, which are both associated to the local tensional stress field of a likely left-lateral strike-slip transfer structure or in the extrados of a fold. By examining both natural gas macroseepage and diffuse flux, it is shown that local structures control the fluid ascent and contribute to the emission of hydrocarbon gases and fluids at the Earth's surface. Understanding the structural control of carbon emissions at the Nirano Salse is also important for evaluating the carbon budget at the site, particularly in areas where there are detectable surface emissions. The study has implications for geologic, environmental, and economic issues, including hydrocarbon exploration, hazard assessment, and impact on the atmospheric carbon budget. Furthermore, the outcomes have an important implication to evaluate the potential for dangerous abrupt mud eruptions, and the site safety in proximity to the mud volcanoes.

AN IMPROVED ANALYTICAL APPROACH FOR MODULATION-PARAMETRIC PROCESSES IN OSCILLATING SYSTEMS RESEARCH

Reversibility principle of modulation-parametric interactions is formed, which is the basis for effective control of equivalent impedances in oscillation systems. A classification of oscillating systems in which there may be forces aimed at changing the effective reactive parameters and dissipation is given. Analytical approach for the study of modulation and parametric processes in oscillation and self-oscillation sys-tems under the small external signals influence is proposed. The heuristics of under-standing the modulation-parametric interactions reversibility are demonstrated. On the basis of the formulated and substantiated principle of reversibility of modula-tion-parametric interactions, a “dissection” of the physical mechanism underlying it was carried out, and also demonstrated the mechanism of its effective practical ap-plication. The analytical approach implemented in the work combines the advantages of analytical methods based on differential equations, which most fully and accurately describe the objects and phenomena under study, with complex spectral methods, which provide the most compact notation of equations, a clear physical interpretation of the internal structure of signals and facilitate mathematical analysis.

“DompeKeys”: a set of novel substructure-based descriptors for efficient chemical space mapping, development and structural interpretation of machine learning models, and indexing of large databases

The conversion of chemical structures into computer-readable descriptors, able to capture key structural aspects, is of pivotal importance in the field of cheminformatics and computer-aided drug design. Molecular fingerprints represent a widely employed class of descriptors; however, their generation process is time-consuming for large databases and is susceptible to bias. Therefore, descriptors able to accurately detect predefined structural fragments and devoid of lengthy generation procedures would be highly desirable. To meet additional needs, such descriptors should also be interpretable by medicinal chemists, and suitable for indexing databases with trillions of compounds. To this end, we developed—as integral part of EXSCALATE, Dompé’s end-to-end drug discovery platform—the DompeKeys (DK), a new substructure-based descriptor set, which encodes the chemical features that characterize compounds of pharmaceutical interest. DK represent an exhaustive collection of curated SMARTS strings, defining chemical features at different levels of complexity, from specific functional groups and structural patterns to simpler pharmacophoric points, corresponding to a network of hierarchically interconnected substructures. Because of their extended and hierarchical structure, DK can be used, with good performance, in different kinds of applications. In particular, we demonstrate how they are very well suited for effective mapping of chemical space, as well as substructure search and virtual screening. Notably, the incorporation of DK yields highly performing machine learning models for the prediction of both compounds’ activity and metabolic reaction occurrence. The protocol to generate the DK is freely available at https://dompekeys.exscalate.eu and is fully integrated with the Molecular Anatomy protocol for the generation and analysis of hierarchically interconnected molecular scaffolds and frameworks, thus providing a comprehensive and flexible tool for drug design applications.

THE MICROBIAL “FINGERPRINTS” FROM THE CONTINENTAL LOWER PERMIAN OF POLAND

ABSTRACT Microbes colonize sediment and alter its properties creating a bio-mineral medium. The microbially induced sedimentary structures (MISS) are the fossil record of an interaction between the physical environment and such a medium. The present report documents bedding surface structures from the Cisuralian (Asselian) Sandstone Building Member (BSM) of the Słupiec Formation, a unit that outcrops in the south-western Poland, in the Sudetes Mountains. The BSM represents likely continental (fluvial) sedimentary settings. The sedimentary structures on bedding surfaces in the BSM are interpreted as the MISS. The observations of the bedding structures are supplemented with thin section data that support the microbial interpretation of the bedding surface structures. The Słupiec Formation MISS record supplements the global patchy fossil record of the post-Cambrian (Paleozoic) MISS from the non-marine settings.

Dereplication of calystegines in food plants and wild Solanum Brazilian fruits

Calystegines are potent glycosidase inhibitors with therapeutic potential and are constituents of food and feed with potential toxic effects. This study aims to target calystegines and other nitrogenous substances in food plants. Hydroalcoholic extracts from Solanum tuberosum, Ipomoea batatas, S. lycocarpum, and fruit from S. lycopersicum, S. aethiopicum, S. paniculatum, S. crinitum, and S. acanthodes were analyzed by liquid chromatography–tandem mass spectrometry (HPLC-MS/MS) using an acidic HILIC column. The dereplication approach included data processing using MZMine2, FBMN-GNPS, and structure elucidation and interpretation of the organized data. The calystegines A3, A5, B2, and C1 were identified, and several potential new calystegine analogues: three may correspond to new calystegines of the A-group, one glycosyl derivative of calystegine A3, and two glycosyl derivatives of the B-group. These findings help to direct the search for new calystegines. In addition, the dereplication approach enabled the annotation of 22 other nitrogen compounds.

Shpol’skii effect: new interpretation for the nature of the spectral multiplet structure and Bethe-splitting

New approach to the interpretation of the multiplet structure in the Shpol’skii spectra based on the symmetry consideration of the impurity molecule and crystal matrix is proposed. The reasons and peculiarities of doublet structure formation in the spectra of molecules without inversion center and highly symmetric molecules are considered. It is shown that the structure of electron density distribution in the naphthalene molecule causes a doubly degenerate of the electronic level of its ground state. The calculated data are compared with the experimental results. The main research stages and directions in the field of narrow-line spectroscopy of organic molecules are marked.

Pitfalls in Using Isotopic Distributions for Structural Interpretation by Mass Spectrometry.

This brief cautionary note reports a failure in a common and useful assumption, namely, that the isotopes of the elements occur in their natural abundance ratios in commercially sourced organic compounds. Some commercial sources of tris(pentafluorophenyl)borane, B(C6F5)3, show severely depleted 10B, while materials from other suppliers display natural isotopic abundances. The depletion varies from lot-to-lot, and it was confirmed by inductively coupled plasma (ICP) mass spectrometry. The isotope 10B is used in the nuclear power industry, as a neutron absorber in the power control rods. It is speculated that the residual 11B generated when preparing 10B-enriched boron carbide for control rod use, provides 11B-rich raw material that is then used for commercial B(C6F5)3 synthesis.