Concealed Structure Research Articles

Ore-controlling structures of the Qingchengzi Pb-Zn-Au-Ag orefield, northeastern China and significance for deep ore prospecting: Revealed from gravity and magnetic anomalies

Located in the middle of Liaodong Rift, the Qingchengzi orefield is an important Pb-Zn-Ag-Au polymetallic mining area in Northeast China. The Pb-Zn-Au-Ag mineralization mainly occurs in the Liaohe Group strata and is closely related to Indosinian and Yanshanian magmatic intrusive bodies. Currently the Qingchengzi orefield is poorly explored at depths greater than 1500 m, with no large deep concealed gold deposit being discovered yet. This study focused on delineating deep concealed ore-controlling structures from the local gravity and aeromagnetic anomalies in different wavelet orders acquired by the application of discrete wavelet transform (DWT), and evaluating their potential for undiscovered gold-rich polymetallic mineralization in the Qingchengzi orefield. We started from summarizing the characteristics of gravity and magnetic anomalies corresponding to the ore-controlling structures obtained from surface geology, exploration profiles and drilling results. Under the guidance of the correspondence, we interpreted the structural control factors of the tectonic-magmatic metallogenic system for the whole Qingchengzi orefield, such as faults, strata, magmatic bodies and mineralized alteration belts. Based on the spatial relationship between the known deposits and structural factors interpreted from gravity and magnetic anomalies, it is concluded that the gold-rich polymetallic deposits and mineralization are controlled by five major deep regional faults (two in the NE direction and three in the NW direction). Moreover, the borders of the Indosinian and Yanshanian concealed magmatic intrusions, as well as the intersections of deep regional faults are more favorable for the deposition of gold-rich polymetallic minerals. A NNE-trending concealed structure was found in the middle of our study area, connecting the Shuangdinggou, Qingchengzi, Xinling and Gujiagou intrusions, serving as a possible channel for magmatic activities in the Indosinian. The forward modeling results on the gravity and magnetic data of profile L1 indicates that the Liaohe Group strata and the possible Mesozoic concealed intrusion lies beneath the Paleoproterozoic Dadingzi granite. This finding supplements the traditional understanding that the Paleoproterozoic Dadingzi granite is the deepest boundary for ore prospecting, and provides new thoughts searching for deep-seated ore bodies for the Xiaotongjiapuzi ore deposits.

Study on Application of Comprehensive Geophysical Prospecting Method in Urban Geological Survey—Taking Concealed Bedrock Detection as an Example in Dingcheng District, Changde City, Hunan Province, China

In order to ascertain the concealed bedrock and its spatial distribution in an urban low-resistance coverage area of a typical lacustrine basin in Hunan Province, a multi-method comprehensive experimental study was carried out in Dingcheng District, Changde City where there are multiple sets of strata and fault structures. In this study, the wide-area electromagnetic method and microtremor survey were utilized on the basis of traditional methods, including the high-density resistivity method and controlled-source audio-frequency magnetotelluric method, to infer the concealed Cambrian limestone, fault structure, and vertical distribution of strata and the results were verified by drilling. The results indicate that the wide-area electromagnetic method is effective to explore the bedrock and concealed structure in urban geological survey. The microtremor method has an obvious effect on the detection of the Cretaceous and Quaternary silty strata within 100 m. The study may provide references for similar projects in this area.

A study of the dynamic damage characteristics of Rock-Like materials with different connectivity of concealed structural surfaces

In order to explore the dynamic mechanical properties and failure laws of rock masses with different connectivity of concealed structural surfaces, this study used rock-like materials to produce specimens with concealed structural surfaces at different connectivity levels. An improved Separated Hopkinson Pressure Bar (SHPB) experimental system was applied in combination with the finite element software ANSYS/LS-DYNA. Then, the dynamic properties, energy transfer laws, and failure characteristics of the concealed structures with different connectivity were analyzed. The research results showed that the peak stress and yield stress level of the specimen gradually decreasedas connectivity parameter increases. However, it was observed that the average strain rate continued to increase with the increased connectivity of the structural surface under the same impact velocity. The stress–strain curve of the specimen with a concealed structure appeared as “stress bimodality.” This phenomenon was determined to be related to the structural surface connectivity and impact velocity of the specimen. In addition, the specimen’s energy absorption rate first increased and then decreased with the increases in the structural surface connectivity. It was found that the reflection coefficient gradually increased, and the transmission coefficient exhibited a negative linear relationship with the connectivity of the structural surface. In addition to tensile cracks, vertical arc-shaped shear cracks also appeared in the failure mode of specimens with concealed structural surfaces. Moreover, the order of the appearance of the tensile cracks and compression-shear cracks, as well as the sizes of the cracks, were determined to be closely related to the structural surface connectivity. This study’s research results also revealed the deformation and failure laws and energy evolution characteristics of the rock-like materials with different concealed structural surface connectivity under different velocity impact loads.

Failure mechanism of coal seam floor with concealed structure and evolution law of confined water seepage

Failure mechanism of coal seam floor with concealed structure and evolution law of confined water seepage

Bending Performance of Precast Lightweight Aggregate Concrete Exterior Wallboard with a Concealed Rib Sandwich Structure

A new type of precast lightweight aggregate concrete exterior wallboard is proposed in this study. It is composed of inner and outer panels, an insulation layer, and concealed ribs. After adjusting the mixing ratio of lightweight aggregate concrete, light weight, bearing capacity, and good workability were guaranteed. The flexural performance of the composite exterior wallboard was studied by testing and numerical modeling of four wallboards, and the results of deflection, crack morphology, failure mode, and ultimate flexural capacity were then obtained. Additionally, the cracking and bending properties of the composite exterior wallboard were observed, and the calculation method of bending capacity and the cracking moment was studied. The calculated results coincided with the experimental data; therefore, this study provides a reference to the design and application of prefabricated exterior wallboards.

An Effective Approach for Modular Community Detection in Bipartite Network Based on Integrating Rider with Harris Hawks Optimization Algorithms

The strenuous mining and arduous discovery of the concealed community structure in complex networks has received tremendous attention by the research community and is a trending domain in the multifaceted network as it not only reveals details about the hierarchical structure of multifaceted network but also assists in better understanding of the core functions of the network and subsequently information recommendation. The bipartite networks belong to the multifaceted network whose nodes can be divided into a dissimilar node-set so that no edges assist between the vertices. Even though the discovery of communities in one-mode network is briefly studied, community detection in bipartite networks is not studied. In this paper, we propose a novel Rider-Harris Hawks Optimization (RHHO) algorithm for community detection in a bipartite network through node similarity. The proposed RHHO is developed by the integration of the Rider Optimization (RO) algorithm with the Harris Hawks Optimization (HHO) algorithm. Moreover, a new evaluation metric, i.e., h-Tversky Index (h-TI), is also proposed for computing node similarity and fitness is newly devised considering modularity. The goal of modularity is to quantify the goodness of a specific division of network to evaluate the accuracy of the proposed community detection. The quantitative assessment of the proposed approach, as well as thorough comparative evaluation, was meticulously conducted in terms of fitness and modularity over the citation networks datasets (cit-HepPh and cit-HepTh) and bipartite network datasets (Movie Lens 100 K and American Revolution datasets). The performance was analyzed for 250 iterations of the simulation experiments. Experimental results have shown that the proposed method demonstrated a maximal fitness of 0.74353 and maximal modularity of 0.77433, outperforming the state-of-the-art approaches, including h-index-based link prediction, such as Multiagent Genetic Algorithm (MAGA), Genetic Algorithm (GA), Memetic Algorithm for Community Detection in Bipartite Networks (MATMCD-BN), and HHO.

Study of hidden structure detection for tunnel surrounding rock with pulse reflection method

• Hidden structure detection instrument by starting with the data of all-round acoustic pulse reflection sequence. • 3D imaging and characteristic parameter estimation comprehensive technical system. • A new method of tunnel surrounding rock hidden structure detection. The hidden structure is one of the bottlenecks restricting the construction of underground engineering such as tunnels. The hidden structure detection of surrounding rock on the planned route in the tunnel construction early stage has become an important engineering scientific problem to be studied and solved. In view of the above problems, this paper puts forward a solution idea based on the acoustic total pulse reflection method, and develops a pulse reflection detection instrument for the tunnel surrounding rock concealed structure. It is proposed to solve the location problem of concealed structures by starting with the data of all-round acoustic pulse reflection sequence, and to form an optimization scheme of scanning acoustic 3D inversion imaging and data visualization of tunnel surrounding rock based on 3D full pulse sequence inversion method. In view of the estimating characteristic parameters difficult problem of the surrounding rock concealed structure, a method estimating the characteristic parameters of the concealed structure based on the numerical search is proposed. If there is a coupling layer between the acoustic transducer and the rock wall through the physical model test, the phase characteristic relationship between the acoustic signal and the detection target can be used to solve the difficult problem estimating the characteristic parameters of the surrounding rock concealed structure in the actual project. Finally, a comprehensive technical system of 3D imaging and characteristic parameter estimation for the tunnel surrounding rock concealed structure is formed, and the technology is applied to the detection of actual tunnel surrounding rock The detection results are basically consistent with actual characteristics. The practical application results show that the estimation technology of hidden structural characteristic parameters can effectively solve the location problem of hidden structure in the surrounding rock structure detection before the design and construction stages of tunnel, especially the estimation of location, orientation and hidden structure sound velocity can be realized, and the function of rock structure detection technology can be expanded, which has a good application prospect and promotion value.

Computed tomography scanning as a tool for linking the skeletal and otolith‐based fossil records of teleost fishes

AbstractMicro‐computed tomography (μCT) scanning now represents a standard tool for non‐destructive study of internal or concealed structure in fossils. Here we report on otoliths found in situ during routine μCT scanning of three‐dimensionally preserved skulls of Palaeogene and Cretaceous fishes. Comparisons are made with isolated otolith‐based taxa to attempt correlations between the body fossil and otolith fossil records. In situ otoliths previously extracted mechanically from specimens of Apogon macrolepis and Dentex laekeniensis match our μCT models. In some cases, we find a high degree of congruence between previously independent taxonomic placements for otolith and skeletal remains (Rhinocephalus, Osmeroides, Hoplopteryx). Unexpectedly, in situ otoliths of the aulopiform Apateodus match isolated otoliths of Late Cretaceous age previously interpreted as belonging to gempylids, a group of percomorph fishes that do not appear in the body fossil record until the Palaeogene. This striking example of convergence suggests constraints on otolith geometry in pelagic predators. The otoliths of Apateodus show a primitive geometry for aulopiforms and lack the derived features of Alepisauroidea, the lizardfish clade to which the genus is often attributed. In situ otoliths of Early Cretaceous fishes (Apsopelix and an unidentified taxon) are not well preserved, and we are unable to identify clear correlations with isolated otolith morphologies. We conclude that the preservation of otoliths suitable for μCT scanning appears to be intimately connected with the taphonomic history, lithological characteristics of surrounding matrix, and syn‐ and postdepositional diagenetic effects.

Geophysical expression of buried range-front embayment structure: Great Sand Dunes National Park, Rio Grande rift, Colorado

Great Sand Dunes National Park and Preserve (GRSA, Colorado) lies along the eastern margin of the San Luis Basin and the tectonically active Sangre de Cristo fault system that are part of the northern Rio Grande rift. GRSA lies within a prominent embayment in the range front where two separate sections of the Sangre de Cristo fault system intersect. Fault scarps are observed along both intersecting fault zones within older basin-fill alluvium, but have been obscured by the actively migrating dunefield. The dune sand is also strongly magnetic, locally limiting the usefulness of aeromagnetic methods for mapping concealed structure. This study uses airborne geophysical methods, primarily airborne gravity gradient data, along with constraints from geologic mapping and limited subsurface data and groundwater modeling, to interpret the subsurface basin geometry and range-front structure of the embayment. Using forward modeling of the gravity gradient data and locations of faults inferred from gravity gradient and aeromagnetic lineaments, several previously unrecognized tectonic elements are interpreted adjacent to the range front. Some of the largest rift-­related fault offsets are demonstrated to be basinward of the normal fault zones mapped at the surface along the range front of the Sangre de Cristo Mountains, along faults concealed under the dunefield and subparallel to the two fault sections. A fault-bounded structural bench, likely composed of Proterozoic rocks, underlies most of the high dunefield at depths of 500 m to 1 km. The bench is truncated on its southwest margin by a northwest-trending, southwest-dipping normal fault. A northeast-trending, northwest-dipping normal fault with ∼600 m of estimated relief lies under the southern margin of the dunefield and bounds a structurally higher bench of Proterozoic rocks concealed at <400 m depth near the range front. The northwest- and northeast-trending geophysical lineaments generally correspond well with the trends of faults mapped at the surface, and with both pre- and syn-rift structures in the Sangre de Cristo Mountains. Aeromagnetic anomalies are explained by variations in the magnetization of pre-rift rocks, and the strongly magnetic dune sand.

A Monoclausal Analysis of Menominee Wh-Questions

This paper provides a thorough description of wh-questions in Menominee (Algonquian) and further makes the argument that basic or unmarked wh-questions in the language are best analyzed as having a monoclausal structure. Biclausal analyses which have been given for such wh-questions in other Algonquian languages propose a concealed cleft structure, while monoclausal analyses which have been given argue instead that wh-words undergo movement to Spec,CP. We show that in addition to the basic wh-construction in Menominee, there is also a cleft wh-construction which can be identified by the presence of an overt copula. Based on this and other evidence, we argue that a monoclausal analysis works best for the unmarked wh-questions in Menominee.

From the EEL to the EGO: Psychoanalysis and the Remnants of Freud's Early Scientific Practice

While numerous historiographical works have been written to shed light on Freud's early theoretical education in biology, physiology, and medicine and on the influence of that education on psychoanalysis, this paper approaches Freud's basic comprehension of science and methodology by focusing on his early research practice in physiology and neuranatomy. This practice, taking place in the specific context of Ernst Brücke's physiological laboratory in Vienna, was deeply concerned with problems of visuality and the revelation of hidden organic structures by use of proper preparation techniques and optical instruments. The paper explores the connection between such visualizing practices, shaped by a physiological context as they were, and Freud's later convictions of the scientific status of psychoanalysis and the function of its method as means to unveil the concealed structure of the "psychical apparatus".

Using Lagrangian models to assist in maritime management of Coastal and Marine Protected Areas

ABSTRACT Delpeche-Ellmann, N.C., Soomere, T., 2013. Using Lagrangian models to assist in maritime management of Coastal and Marine Protected Areas Several previous attempts to mitigate current-driven environmental risks to the nearshore via a concealed structure of surface Lagrangian transport have assumed a constant value to the entire nearshore. We extend these attempts towards more realistic accounting for the Coastal and Marine Protected Areas (MPA). We investigate the effects shifting the present fairway would have on the amount of current-driven pollutants the MPA may receive. The Rossby Centre Ocean circulation model, the TRACMASS Lagrangian trajectory model and statistical methods were employed to identify patterns of current-driven transport in the Gulf of Finland, the Baltic Sea, for the period 1987–1991. Pollution point sources were assumed to occur along the fairway. An analysis was made on how much of the pollution travelled to each of the MPA and the time frame involved. The existing fairway...

High Speed Terahertz Pulse Imaging in the Reflection Geometry and Image Quality Enhancement by Digital Image Processing

We describe the formation and enhancement of two dimensional pulsed terahertz (THz) images obtained in the reflection geometry with a high-speed optical delay line. Two test objects are imaged and analyzed with respect to material information and concealed structure. Clear THz images were obtained with various imaging modes and were compared with the X-ray images. The THz image of a sample revealed material features that the X-ray image cannot distinguish. We could enhance the THz image quality using various image processing techniques, such as edge detection, de-noising, high-pass filtering, and wavelet filtering.

Application of the high-resolution EM method in the investigation of B Tunnel

A successful case history of exploring for concealed structure using the high-resolution EM method in the investigation of the West-East Gas Pipeline Project’s B Tunnel is presented in this paper. The high frequency electromagnetic image system named STRATAGEM EH4, operating at frequencies ranging from 90 KHz to lHz, was used for data acquisition. The orthogonal components of the electromagnetic field were measured during the field acquisition and the relevant electromagnetic attributes of the object body were extracted from the electromagnetic data. Hybrid sources, consisting of natural and full tensor-controlled sources, were utilized to produce high-quality electromagnetic field data. B Tunnel lies in the western part of Hubei province, at depths of less than 200 m. The geologic setting of B tunnel is very complex. Following an initial geologic investigation, an outcrop considered to be a bedrock interface by investigators, collapsed during tunneling operations. A second investigation applied high-resolution EM and seismic refraction methods to reveal a more complex geologic structure along the tunnel route. The predicted rock classes and fault were encountered during the subsequent tunneling operations.

Basin dynamics and mineralisation, McArthur Basin, northern Australia

The Broadmere Structure is a concealed complex inversion structure that developed in a well preserved part of the Batten Trough in the southern McArthur Basin of northern Australia. The structure formed in response to a number of major tectonic events over a period of at least 600 million years. Evaluation of more than 300 km of seismic data gathered across the structure has provided significant insight into the evolution of the basin architecture which, in turn, has provided a framework for understanding the spatial and temporal distribution of mineralisation. The Palaeoproterozoic McArthur Basin, a polyphase basin with a long and complex evolutionary history, was initiated some time after 1.8 Ga as a sag basin following mantle activity associated with supercontinent assembly. This shallow sag then began to accumulate a relatively mature clastic sedimentary succession with interspersed basic volcanics. Subsequent extension of the weakened crust, beginning at approximately 1730 Ma, led to the development of a series of normal faults and half grabens within zones (e.g. Batten Trough) defined laterally by major strike slip fault complexes. The half grabens were filled initially by volcaniclastic sediments with associated bimodal volcanics that were later followed by mixed carbonate and clastic sediments exceeding 8 km in thickness. A major change in basinal and regional dynamics between 1575 and 1500 Ma (Isan Orogeny) led to the inversion of the thickened succession overlying the half grabens and extensive erosion of earlier depositional units, followed by deposition of a further 3 km of shallow marine clastic sediments. The analysis of the Broadmere Structure has provided a simple framework in which to evaluate prospectivity. The primary northwest striking half grabens formed localised anoxic, sediment starved depocentres in which organic rich sediments that potentially host mineralisation accumulated. The distribution of subsequent ore bodies is a function of the timing of fluid movement and the nature of fluid pathways, as determined by the evolving basin architecture. Fluids moved laterally through the permeable channels into the Batten Trough in two stages. Spatial data show that Pb and Zn occurrences lie close to the bounding faults, while Cu occurrences are distributed across the width of the Batten Trough, supporting a more or less syngenetic origin for the former and a much later, post inversion, epigenetic origin, for the latter. Mineralisation thus occurred in association with inversion structures formed above the primary half grabens that were generally concealed by later sedimentation. Because the half grabens occur at regularly spaced intervals along the Batten Trough there may well be more mineral occurrences similar to the McArthur River deposit. Clearly, these conclusions must be integrated into any exploration strategy.

Oedipus Again: a Critical Study of Charles Laughton’s The Night of the Hunter

In this paper the Oedipus complex is reexamined through a film, The Night of the Hunter. Study reveals a concealed fairy tale structure, a structure that, when presented against a mythic backdrop, is ideal for presenting a certain kind of oedipal situation, that of a vulnerable damaged father and couple (indeed, couples), revealing a skewed oedipal situation. The film, produced in 1954 and looked at forty years later in the context of psychoanalytic writings of the last decade (Bergmann, Feldman, Herman, Simon), provides a matrix with which to reexamine a fundamental psychoanalytic concept, the Oedipus complex. It is the mutual enrichment of art and psychoanalysis that this paper addresses.

Typological restoration of four rural churches. Madrid, Spain

The article describes the restoration of four rural churches in the Madrid Community with a common set of problems: the typological and structural loss, mainly wooden roof and the retrieval of the architectural scheme in order to enable its comprehension in the historical context. In the church of Camarma, Mudejar elements: apse, ante apse, roofing and mural paintings are restored and displayed. Also, the structural problems in walls that were close to collapsing are solved. En Torremocha, the concealed structure is being revealed and its architectural evolution is shown step by step with an easily comprehensible scheme. The Braojos case represents the elimination of inappropriate actions through the retrieval of the construction scheme of a traditional language and with traditional materials. On the contrary, in Chapineria, a case similar to that of the Braojos one, what is required is the spatial restoration through very current architectural, constructive and formal solutions.

Short Paper: Evidence of negative structural inversion beneath central England from new seismic reflection data

A major seismic reflection transect, acquired by the British Geological Survey between 1984 and 1986, has elucidated the deep geology and structure of some well-known surface features of central England. The Worcester Basin, a Mesozoic extensional graben system, is bounded to west and east by major, sub-planar normal faults which formed by the extensional reactivation of much older structures; respectively the Malvern Axis and a similar though concealed structure forming its mirror image to the east. Within the Worcester Basin a thick Permo-Triassic sequence rests directly upon Precambrian basement rocks. To the west and east, Permo-Triassic rocks are thin or absent, but relatively thick Palaeozoic sequences are preserved above the Precambrian. These strikingly different successions, together with the fault geometry, suggest that the Worcester Basin lies within a major, inverted oblique-slip fault system or flower structure. In Palaeozoic times transpressivt stresses led to reverse faulting along the Malvern Axis and its complementary structure to the east with consequent regional uplift of the intervening tract and the formation of a positive flower structure. In Permian and early Mesozoic times, transtensional stresses caused collapse and negative inversion of the flower structure and consequent subsidence of the Worcester Basin.

STRUCTURAL SIGNIFICANCE OF GRAVITY SURVEYS IN THE VIRGINIA CITY—MOUNT ROSE AREA, NEVADA AND CALIFORNIA

Gravity surveys were made in the Mount Rose and Virginia City quadrangles to investigate the concealed Cenozoic structure of the alluviated basins and to explore for significant gravity differences between basins and ranges. The gravity data have been computed as complete Bouguer anomalies, which incorporate corrections for all the accurately assessible factors affecting gravity values, including topographic irregularities but not isostatic compensation. Gravity variations in the basins are closely related to changes in thickness of Cenozoic sedimentary rocks and alluvium in the basins. The gravity data indicate that light Cenozoic sedimentary rocks in Washoe Valley are at least 1800 feet thick; that the sediments in the northern part of Steamboat Valley are only about 600 feet thick and thin gradually eastward but thin abruptly to the west near Steamboat Hills; that east of Reno, between Sparks and the Virginia Range, sediments are roughly 2800 feet thick and thin abruptly about half a mile west of the range; and that in the basin west of Reno sediments are locally 1800 feet or more thick. The variations in thickness reflect important structural deformation in the basins. The late Cenozoic structures that separate the basins from the mountains are a complex of contemporaneous faults and folds; folding is predominant in some areas and normal faulting in others. From the eastern boundary of the area surveyed, the gravity values decrease westward about 1 mgal per mile, a total of 30 mgals, to a minimum at the east side of the Carson Range of the Sierra Nevada and then increase toward the main Sierra block. There is little or no gravity expression of the Virginia Range or the Carson Range relative to sediment-free parts of the basins adjacent to the ranges. Gravity measurements of the Coast and Geodetic Survey combined with the present measurements demonstrate that the Bouguer anomaly from San Francisco eastward shows a general inverse relationship to elevation but is a minimum along the east side of the Carson Range rather than at the main summit of the Sierra. This gravity profile may be the result of a thickening of the earth9s crust eastward beneath the higher part of the continent, combined with a smaller effect from greater-than-average amounts of granitic rock in the crust of the Sierran region.