Dome Structure Research Articles

Robustness Analysis of a Flexible Cable-Strut Tensile Structure

Currently, the robustness analysis of structure is primarily related to rigid structures, and little has been done to study the robustness of spatial flexible cable-strut tensile structures with larger span, more complex forms, lower redundancy, more sensitivity to unexpected interference such as construction deviations, etc. Based on the $$ H_{\infty } $$ theory, this paper starts with the fundamental theory and develops analysis method for the robustness of flexible cable-strut tensile structures, and then the relationships between the structural robustness and some design parameters such as initial pre-stress level, load distribution form, structural span, cross-section area, rise-span ratio, etc. are analysed through a case study of a concrete cable-strut tensile structure in China. On this basis, the effects of construction errors such as element-length error and supporting node position error are further analysed. Finally, the importance of each kind of element is analysed by means of conceptual removal of element. The results show that the higher the initial pre-stress level, the larger the element cross-section, the smaller the structural span, the larger the rise-span ratio and the more uniform the load distribution, the stronger the structural robustness. In the limited construction error range, the element-length error and the supporting node position error have little effects on the robustness of the structure. The hoop cables are the more important elements and the elements in inner region of the structure are of comparatively lower importance in the cable dome structure in this study.

Crustal growth in the Mesoarchean plutonic belt from the Memve'ele area (Ntem Complex-southwestern Cameroon): Evidence of “early earth” transpressional tectonics

The Mesoarchean crust of the plutonic belt of the Memve'ele area lies in the southwestern part of the Ntem Complex (NTC), Cameroon. Emplacement of these rocks resulted from both gravity and tectonic driven vertical flow perpendicular to the direction of shortening at the time of partial melting and magmatic accretion. Such deformation patterns suggest the occurrence of a long-lived hot orogen and may explain a nearly isobaric retrograde pressure-temperature (P-T) path recorded within high-T, low- to medium-P metamorphic rocks. However, in the Memve'ele shear zone (MSZ), a metamorphic gradient runs from granulite to green-schist facies. Structural analysis reveals four continuous ductile deformations. The first stage is characterized by the emplacement of dome and basin structures, the second stage is marked by coeval diapiric movements and a transpressional shear zone, the third stage is marked by both transpressional and lateral flow regimes, and the last stage is marked by horizontal constrictional strain. These features indicate that the Mesoarchean crust is affected by a long-lived horizontal shortening deformation (D1-D3) coeval with vertical movements in which concentric cleavages occur around domes. Thus, the studied area can be considered as exemplifying an “Early Earth” style tectonics. The structural patterns in the MSZ contain zone of high-strain rocks belonging to the deep and shallow/mid crusts that have recorded transpressional tectonics. The compressional strain regime in which results coeval steep to shallow dipping structural features and “dome and basin” geometries associated to MSZ activities contributed to maintaining a stable crustal thickness in the Memve'ele area during Mesoarchean orogeny.

Artificial neural network-based geometry compensation to improve the printing accuracy of selective laser melting fabricated sub-millimetre overhang trusses

Abstract Selective laser melting processes deposit and join metal powders to near net shape in a layer-by-layer manner. The process of melting and re-solidification of several layers of deposited material can result in geometric deviations, and the impact is particularly significant for sub-millimetre structures oriented at a wide range of overhang angles with respect to the building platform. This paper assesses and benchmarks the capabilities of a neural network-based geometric compensation approach for truss lattice structures with circular cross-sections. The neural network method is capable to generate free-form cross-sections with enhanced geometric freedom for compensation compared to more established analytical compensation approaches limited to predefined geometric shapes. For neural network training, lattice dome structures composed of trusses with different overhang angles were designed and printed by selective laser melting and measured via X-ray computed tomography, resulting in point cloud data sets containing more than 20,000 data points for each overhang angle. For experimental validation, neural network-compensated dome structures were benchmarked against dome structures with elliptical parameter compensation. Results show that the neural network compensated lattice trusses achieve higher printing dimensional accuracy compared to the uncompensated structures and those compensated based on elliptical parameter estimates.

South China Sea documents the transition from wide continental rift to continental break up

During extension, the continental lithosphere thins and breaks up, forming either wide or narrow rifts depending on the thermo-mechanical state of the extending lithosphere. Wide continental rifts, which can reach 1,000 km across, have been extensively studied in the North American Cordillera and in the Aegean domain. Yet, the evolutionary process from wide continental rift to continental breakup remains enigmatic due to the lack of seismically resolvable data on the distal passive margin and an absence of onshore natural exposures. Here, we show that Eocene extension across the northern margin of the South China Sea records the transition between a wide continental rift and highly extended (<15 km) continental margin. On the basis of high-resolution seismic data, we document the presence of dome structures, a corrugated and grooved detachment fault, and subdetachment deformation involving crustal-scale nappe folds and magmatic intrusions, which are coeval with supradetachment basins. The thermal and mechanical weakening of this broad continental domain allowed for the formation of metamorphic core complexes, boudinage of the upper crust and exhumation of middle/lower crust through detachment faulting. The structural architecture of the northern South China Sea continental margin is strikingly similar to the broad continental rifts in the North American Cordillera and in the Aegean domain, and reflects the transition from wide rift to continental breakup.

Multiple rejuvenation episodes of a silicic magma reservoir at the origin of the large diatreme-dome complex and porphyry-type mineralization events at Cerro de Pasco (Peru)

The Cerro de Pasco district in central Peru hosts one of the world largest porphyry-related epithermal polymetallic deposits. The district is centered onto a large diatreme-dome complex crosscut by numerous dacite to rhyodacite bodies showing domal structures and quartz-monzonite dykes. Three temporally distinct high-temperature porphyry-type mineralization events have been recognized (PM1, PM2, and PM3). Dating of the latter by molybdenite Re-Os and by zircon U-Pb (LA-ICP-MS and CA-ID-TIMS) geochronology complements the already available dataset of zircon U-Pb ages of the subvolcanic and volcanic rocks mostly dacitic in composition occurring in the district and shows the existence of successive short-lived episodes (<100 kyr) of shallow magmatic activity and porphyry-type mineralization. The new geochronology data indicate that the magmatic system was active during more than 400 kyr, spanning from 15.59 ± 0.12 Ma to 15.16 ± 0.04 Ma, punctuated by three porphyry-type mineralization events that are precursors (maximum gap of 0.9 Myr) of the last stage of epithermal polymetallic mineralization at Cerro de Pasco. Detailed petrographic and geochemical (whole rock and minerals) studies have been performed and silicate melt inclusions hosted in quartz phenocrysts from the subvolcanic and volcanic rocks emplaced between and after the different porphyry-type mineralization events have been analyzed by LA-ICP-MS. Our results suggest that prior to their emplacement at shallow level, magmas were stored at depth with a high degree of crystallinity (>50%) at pressures between 0.9 and 3.4 kbar and at temperatures between ~680 °C and ~725 °C. At such conditions, magma is beyond the point of rheological lock-up and is not eruptible. The emplacement of the mostly dacitic subvolcanic and volcanic rocks has required a series of rejuvenation events of the upper crustal high-crystallinity silicic magma reservoir. Field relationships and geochronology indicate that emplacement of the subvolcanic and volcanic rocks is preceded each time by high-temperature (>600 °C) quartz-pyrite-magnetite ± chalcopyrite and quartz-molybdenite veining forming the three recognized porphyry-type mineralization events. Hydrothermal quartz of these veins host silicate melt inclusions, a rare feature in hydrothermal veins. Their composition determined by LA-ICP-MS analysis indicates that the mineralizing fluids, potentially sourced from intermediate magma recharges, have circulated in a magma reservoir in which the residual interstitial melt was more evolved than the melt trapped as inclusions in the magmatic quartz. The combined geochemical and geochronological data obtained show that several episodes of rejuvenation of a highly crystallized upper-crustal silicic magma reservoir, probably triggered by intermediate magma recharges and by circulation of CO2- and S-rich fluids exsolved from them, are at the origin of the large diatreme-dome complex and porphyry-type mineralization events at Cerro de Pasco.

Heat and mass transport in sublacustrine vents in Yellowstone Lake, Wyoming: In-situ chemical and temperature data documenting a dynamic hydrothermal system

Recent advances in the development of in-situ chemical and temperature sensors have shown great promise as a means to investigate time series changes in marine and terrestrial hydrothermal systems. Here we apply this technology to assess chemical and physical controls on sublacustrine vent fluids in Yellowstone Lake, WY. Autonomous sensor systems were deployed in August 2017 using ROV assets to position instruments at two sites in the Deep Hole region of the Lake, off-shore from Stevenson Island. Earlier studies have documented that fissure related depressions (~120 m water depth) in this region host numerous vents issuing high enthalpy, CO2 saturated and H2S bearing vapor, at temperatures in excess of 150 °C. The YSZ (ceramic)-based in-situ chemical sensors deployed here were designed to measure pH and redox at 60 s intervals for up to one year. Two titanium-sheathed thermocouples, one coupled directly to the electrochemical sensor and another, independently powered and positioned slightly deeper in vents at deployment sites, provided insight on maximum temperature in the near surface region. In addition to in-situ chemical and temperature data, vent fluid samples were acquired at the outset and during recovery with a novel isobaric system that maintains lake bottom pressure, precluding fluid-sample de-gassing. At the same time, push cores of vents and in the near vent region were also acquired. The mineralized cores provide evidence of long term mass transfer processes, while also facilitating insertion and stabilization of the sensor units on the lake floor. Recovery of the sensors documented similar chemical controls at both sites, suggesting compositionally invariant vapor influx, characterized by moderately low pH (~4–5) and reducing conditions, buffered by CO2 and H2S, respectively. Accordingly, the diatomaceous sediment was extensively altered to kaolinite and pyrite. Temperature variability at the two sites was especially significant. One site (Site B), situated on the slope of what might be a hydrothermal domal structure, demonstrated noteworthy cooling and heating episodes that may be associated with hydrothermally or seismically triggered sediment slumping events. Upon instrument recovery in 2018, the vent site was largely sediment covered and the sensor insert showed evidence of dis-location and melting by conductive heating under the hot sediment overburden. The initially active and high temperature vent fluid (~148 °C) had largely ceased and replaced by diffuse flow venting at the margin of the previous up-flow zone. The time series in-situ chemical and physical data obtained in the course of the study document the existence of a dynamic hydrothermal system in time and space, while underscoring the challenges of research of this type in such environments.

The Late Cenozoic crustal shortening in the north‐east margin of the Qilian Shan: Evidence from the Fengle Basin, Gansu Province

The north‐east margin of the Qilian Shan forms the front of the northeastward expansion of the Tibetan Plateau. Its Cenozoic crustal shortening is significant for understanding the uplift and growth of the Tibetan Plateau. The Fengle Basin, in the north‐east margin of the Qilian Shan, is characteristic of the typical regional superimposed deformation in Cenozoic strata, documenting the Cenozoic tectonic evolution process in the north‐east margin of the Tibetan Plateau. In this study, we conducted large‐scale geological mapping and regional structural analysis in the Fengle Basin, and rebuilt the two phases of Late Cenozoic crustal shortening deformation in this area: (a) The NW–SE shortening deformation in the Middle–Late Miocene led to the formation of NE‐striking folds in the Fengle Basin, and a hiatus between the Lower and Upper formations of the Gansu Group, probably linked with the far‐field effect of the northwestward subduction of the Pacific Plate. (b) The NE–SW shortening in the Late Miocene–Early Pleistocene overprinted the early NE‐striking folds, resulting in the development of a large‐scale dome structure in this area. The NE–SW shortening is associated mainly with the northeastward growth of the Tibetan Plateau. This study provides crucial evidence for the reconstruction of the intracontinental deformation process in the northeastern periphery of the Tibetan Plateau.

GIS-based approach for the measurement of variability in tectonomorphic signatures using DEM's data: a case study from the Habo Dome in the Kachchh area, India

The Kachchh region of western India is located in a plate interior region, but falls under one of the highest seismic zones of India, having very active crustal deformation and erosion. The drainage system, as well as the geomorphic evolution of the region under a semi-arid climate zone with high to very high strength of rocks in areas with high relief, is dominantly controlled by the seismic instability associated with continual tectonics. In the present paper, we have analysed a block close to the epicentre of the 2001 Bhuj earthquake to understand the role of relative active tectonics in the evolution of domal landscape morphology. Shuttle Radar Topographic Mission Digital Elevation Model data were used to extract drainage network in the GIS platform and evaluate active tectonics using different geomorphic indices of the Habo Hill, the second largest domal structure situated in Northern Hill Range of the Kachchh region. The average cumulative weightage of different geomorphic indices provides a quantitative tool, Index of Relative Active Tectonics (IRAT), which shows significant variations in and around the Habo Dome. Activation of earlier lineaments and generation of new lineaments controlled the morphometric evolution of the fault bound block of the region to form the Habo Dome. The undulating topography in addition to the domal shape of the study area resulted from the differential movements along several active transverse faults striking NE–SW, N–S, and NW–SE, and the regional faults striking E–W (the Kachchh Mainland Fault, the Kas Fault, and the Jikadi Fault). Stress propagations from the Himalayan range in the northeast and Suleiman range in the northwest are identified to be the causative factors for active tectonics and drainage anomalies in the area.

Probabilistic blast load model for domes under external surface burst explosions

The increasing threat of terrorist attacks and the risk of accidental explosions has raised the alarm on structural design, and consequently, the dome structure as the classical building configuration model for public buildings requires safe and reliable defence capabilities against blast loads for the duration of its lifespan. Some deterministic blast load models for specific blast loading scenarios are unable to take the risk of damage into consideration. Therefore, the variability and uncertainty of blast loads need to be studied and quantified. In this study, a probabilistic blast load model is proposed based on a series of repeated field trials. The repeatability of explosive mass and size, detonator type and location, stand-off distance, field condition, data acquisition device and the structure were ensured to realise consistency and standardisation. The experimental results reveal a high degree of variability and uncertainty in the impulse, reflected overpressure and decay coefficient distributed on the studied dome under the effect of external surface explosions. The decay coefficient of a blast wave on the dome has a large variability with a coefficient of variation of 55% when the impulse is less than 8%, which demonstrates that the impulse distributed on the dome has higher precision than other blast load parameters. Furthermore, statistical analysis shows that the normal distribution is the best-fit probability blast load model in an anti-explosion protection design. Furthermore, the accuracy of some blast load predictive methods was also assessed. It was found that the semi-empirical CONWEP air blast code is not an appropriate blast load model for the dome. However, the Arbitrary Lagrangian-Eulerian model is a safer and relatively more accurate method for describing the distribution and variation characteristics of a blast wave distributed on the dome, which can serve as an approximate mean blast load.

The role of structural inheritance in the development of high-displacement crustal faults in the necking domain of rifted margins: The Klakk Fault Complex, Frøya High, offshore mid-Norway

The role of inherited structures during the development of normal faults in continental rifts and proximal domains of passive margins have been extensively studied. Few studies, however, have a focus on deciphering the role of inheritance in the development of high-displacement (>10 km), low-angle (<30°) normal faults in necking domains of passive margins. We integrated and interpreted potential field, 2D and 3D reflection seismic, and well data to study the role of structural inheritance in controlling the location and development of the southern part of the Klakk Fault Complex, offshore mid-Norway. The down-to-the-west Klakk Fault Complex is an N-S non-collinear fault complex that separates the Frøya High in its footwall from the Rås Basin in its hanging wall. The fault segments vary from low-angle planar to listric fault geometries in cross-section, with displacements of 17 km–34 km. These displacements led to syn-rift basement thinning of 12–14 km toward the west, which consequently, also affected the crustal wedge geometry of the necking domains. We identify three intra-acoustic-basement structures based on seismic facies and define their 3D geometry: (i) a bowl-shaped basin, (ii) a hyperbolic surface, and (iii) a domal structure. We discuss their origin and elucidate their role during later rifting. We conclude that pre-existing basement structures controlled the rift-related structures during the second rift phase (thinning), and affected the location, geometries, orientation and segmentation of the high-displacement low-angle faults in the necking domains. The results of this work offer new insights into the development of necking domains in areas where a thick continental crust (>25 km) is present during rifting.

Post-salt trapping mechanism of south-east Pre-Caspian and its application to petroleum exploration

The Kungurian saliferous sediments of the Pre-Caspian sedimentary basin represented by thick stratum of rock salt with interlayered lenses of anhydrites, terrigenous and carbonate rocks. Initial thickness of these sediments estimated as 4000–4500 m at the center of the depression and 1000–2000 m on the edges of the basin. The processes of halokinesis led to formation of more than 1200 salt dome structures represented by salt diapirs and walls, ridges and salt pillows. Number of salt dome related structures of Mesozoic clastic deposits revealed by seismic exploration carried out in 70–90′s of last century are quite common on the south-eastern part of the Pre-Caspian Sedimentary basin. Most of hydrocarbon pools in post-salt clastic rocks have been discovered on fault-related anticline prospects which are derived from salt tectonics morphologically variable (Munyithya et al. Petrol Explor Prod Technol 10: 2257–2267. https://doi.org/10.1007/s13202-020-00917-1, 2020). Other potential traps anticipated in the area are stratigraphic traps, pinch-out and unconformity-related traps, trapped by salt domes and walls or by salt overhang, etc.

New Mapping of the World-Class Jinding Zn-Pb Deposit, Lanping Basin, Southwest China: Genesis of Ore Host Rocks and Records of Hydrocarbon-Rock Interaction

Abstract Jinding is the third-largest known Mississippi Valley-type (MVT) Zn-Pb deposit. It is hosted by a dome containing a suite of complex breccias and sandstones with abundant gypsum and anhydrite. This study presents the results of new geologic mapping of the Jinding open pit and discusses the geology of the deposit in detail. Our new data support a previously proposed model where the deposit is hosted in an evaporite dome created by the diapiric migration of Late Triassic evaporites during Paleocene thrust loading. Nearly all of the mineralization in the deposit is hosted by evaporite diapir-related rocks, including diapiric breccias and laterally extruded material mixed with fluvial sandy sediments (limestone clast-bearing sandstones) and overlying gypsum-sand diapiric units (mainly clast-free sandstones). The new mapping determined that the currently light gray colored sandstones within the Jinding dome were originally red, with the bleaching being a response to calcite and pyrite alteration as a result of pre-ore interaction with hydrocarbons. The bleached sandstones host sphalerite and galena that replaced calcite, and Zn-Pb sulfides also occur in limestone breccias and gypsum-rich rocks as a result of replacement and open space-filling mineralizing processes. The Jinding deposit demonstrates that MVT Zn-Pb mineralization can be hosted by a variety of evaporite diapir-related rocks and indicates that dome structures and the presence of pre-ore hydrocarbons are both important for the formation of Zn-Pb mineralization.

STEEL DOME PROJECT DESIGN BOGOR CONVENTION CENTER OPTIMIZATION FOR BUDGET AND AESTHETIC ARCHITECTURE

A building needs to be considered various aspects to meet the values - both economic value, cost, durability, impact on the environment to aesthetics or beauty. This research was conducted to make a comparison of the Bogor Convention Center project which was built using the Dome structure with the WF Steel Profile which will be replaced by using steel pipe material. The software used in designing steel is SAP2000 Analysis. SAP2000 is a 3D modeling application that is able to design steel structures that produce analysis and calculation results include static analysis, finite element dynamics analysis, as well as images, reports or other outputs from one structural model. As for the depiction using Autocad where Autocad functions to detail the connections that are in the dome frame of the study. Analysis and Design of a spherical dome structure with building functions as a convention center. The structure of the shell is used as the roof of the building so that the aesthetic elements and values of the architecture of the shell structure can be seen its beauty from the inside of the building. The analysis conducted is an analysis of the internal forces and design of reinforcement in the structure.

Shifts in the skyrmion stabilization due to curvature effects in dome- and antidome-shaped surfaces

The study of curvature-induced effects on the properties of nanostructures has become a cornerstone of magnetism. However, several methodologies usually used for studying nanoscale magnetic systems present difficulties for adequately describing curvature. In this work, we present a method that allows studying, under specific conditions, curved dome/antidome surfaces using an equivalent system without curvature. From the described methodology we obtain the phase diagram between easy-normal and skyrmionic magnetization configurations, as a function of spin-orbit coupling, Dzyaloshinskii-Moriya interaction (DMI), and curvature. The effective DMI of the dome structure increases with the curvature. Nevertheless, the effective anisotropy presents the opposite behavior, decreasing with curvature. These results allow us to conclude that an increase in the skyrmion stability is observed in nanostructures having positive curvature. The presented results propose a route that could facilitate the study of curved nanofilms with intrinsic DMI from comparing them with their planar counterparts.

Geochronological and petrological constraints from the evolution in the Saxon Granulite Massif, Germany, on the Variscan continental collision orogeny

AbstractControversy over the plate tectonic affinity and evolution of the Saxon granulites in a two‐ or multi‐plate setting during inter‐ or intracontinental collision makes the Saxon Granulite Massif a key area for the understanding of the Palaeozoic Variscan orogeny. The massif is a large dome structure in which tectonic slivers of metapelite and metaophiolite units occur along a shear zone separating a diapir‐like body of high‐P granulite below from low‐P metasedimentary rocks above. Each of the upper structural units records a different metamorphic evolution until its assembly with the exhuming granulite body. New age and petrologic data suggest that the metaophiolites developed from early Cambrian protoliths during high‐P amphibolite facies metamorphism in the mid‐ to late‐Devonian and thermal overprinting by the exhuming hot granulite body in the early Carboniferous. A correlation of new Ar–Ar biotite ages with published P–T–t data for the granulites implies that exhumation and cooling of the granulite body occurred at average rates of ~8 mm/year and ~80°C/Ma, with a drop in exhumation rate from ~20 to ~2.5 mm/year and a slight rise in cooling rate between early and late stages of exhumation. A time lag of c. 2 Ma between cooling through the closure temperatures for argon diffusion in hornblende and biotite indicates a cooling rate of 90°C/Ma when all units had assembled into the massif. A two‐plate model of the Variscan orogeny in which the above evolution is related to a short‐lived intra‐Gondwana subduction zone conflicts with the oceanic affinity of the metaophiolites and the timescale of c. 50 Ma for the metamorphism. Alternative models focusing on the internal Variscan belt assume distinctly different material paths through the lower or upper crust for strikingly similar granulite massifs. An earlier proposed model of bilateral subduction below the internal Variscan belt may solve this problem.

ESTIMATIVA DE RECURSOS, UTILIZANDO O MÉTODO DE KRIGAGEM ORDINÁRIA, PARA O DEPÓSITO DE TERRAS RARAS ÁREA ZERO, ARAXÁ (MG)

O depósito de elementos terras raras (ETR) Área Zero localiza-se no município de Araxá, Minas Gerais. Situa-se na porção sul da Faixa Brasília, na Província Ígnea do Alto Paranaíba, inserido no Complexo Alcalino-Carbonatítico do Barreiro. O complexo é uma intrusão circular, com aproximadamente 16 km² de área. Apresenta-se como uma estrutura dômica e a mineralização é resultado do enriquecimento supergênico das rochas carbonatíticas, ricas em ETR. A área de estudos encontra-se na porção norte do complexo, em uma área de 400x200 m. O objetivo do trabalho foi quantificação dos recursos através do método de krigagem ordinária, utilizando dados de 61 furos de sondagem diamantada. Análises estatísticas mostraram que o depósito possui uma grande variabilidade de teores. Para executar a krigagem ordinária, o modelo esférico foi ajustado para os variogramas experimentais direcionais. A variografia indicou que a direção de maior continuidade do depósito foi a de 22,5/0 com amplitude de 51 m. O modelo de blocos foi construído com as dimensões 10x10x3 m respeitando o contato entre as unidades. Todas as unidades estão mineralizadas e os recursos do depósito totalizam 10,5 milhões de toneladas com teor médio de 4,75 % de óxidos totais de terras raras.&#x0D; Palavras chave: Geologia. Métodos estatísticos. Elementos terras raras. Krigagem ordinária. Estimativa de recursos.

Structural control and timing of evaporite-related Mississippi Valley-type Zn–Pb deposits in Pucará Group, northern central Peru

The South America MVT belt comprises the deposits of San Vicente, Shalipayco, Florida Canyon, and some minor Zn–Pb occurrences hosting in the carbonates and evaporites of the Pucará Group, in an extension of more than a thousand kilometers from the center to the north of Peru. Structural constraints of the MVT Peruvian deposits are conditioned by deep sub-vertical secondary extension structures with general N, NNE or NNW direction related to strike-slip movements superimposed on previous Andean NW thrust structures. Recent studies on Shalipayco and Florida Canyon deposits point to similar processes of rock formation, diagenesis and mineralization acting in province scale. New isotopic data of Pb–Pb and Rb–Sr in sulfides summed with a compilation of the available data for the evaporite-related MVT deposits and studies on the structural and tectonic evolution of the Peruvian Andes allowed establishing correlations of local process of the deposits to the regional Andean tectonic events. The Florida Canyon saline dome structure was attributed to Juruá Orogeny (157–152 Ma). The stage of dolomitization forming the porous dolostone and evaporite breccia during burial diagenesis is attributed to the period between Juruá and Mochica stages. The oil migration to these reservoir rocks occurred probably during Mochica event (100–95 Ma). The Rb–Sr dating of sphalerite from the Florida Canyon deposit together with temporal field relations indicated that the Zn–Pb sulfide ore formed in or just after Peruvian Orogeny (86-83 Ma).

Effect of Rib beams on stability of R.C.C Dome Structure

Effect of Rib beams on stability of R.C.C Dome Structure

Risk analysis of natural hydraulic fracturing in an overpressured basin with mud diapirs: A case study from the Yinggehai Basin, South China sea

The Yinggehai Basin is a strongly overpressured basin without large-scale faults in the Central Depression Zone. The hydraulic seal capacity of the caprocks over geological history has been the key factor controlling the vertical distribution characteristics of oil and gas. Based on leak-off data, rock mechanics tests and measured pore pressure data, this paper analyses the potential of natural hydraulic fracturing with the fault analysis seal technology (FAST) methodology for caprocks C1 (caprock of the Huangliu Formation) and C2 (caprock of the Meishan Formation) of the diapir belt in the north Central Depression Zone and determines the failure mode and gas sealing capacity of the two caprocks. The results show that gas leakage occurred continuously in both C1 and C2 in the diapir zone (DZ) throughout geological time. However, far from the diapir zone (FDZ), hydraulic leakage occurred only in caprock C2 while no leakage occurred in caprock C1 over geological time. These results are consistent with the gas accumulation that occurred in both the Yinggehai Formation and Huangliu Formation in the DZ but only in the Huangliu Formation in the FDZ. A relatively reasonable explanation is that diapirism promoted natural hydraulic fracture development via the following effects: (i) Diapirism transfers deep overpressure to shallow layers and increases the pressure gradient; (ii) The high-angle fractures associated with diapirism reduce the critical stress condition for the occurrence of natural hydraulic fracturing; and (iii) Diapirism results in the formation of dome structures in shallow layers, causing more shallow burial of caprock in the DZ than the FDZ. Shallowly buried caprocks, which have a relatively lower hydraulic fracture pressure, facilitate gas migration. These effects promoted natural hydraulic fracturing in the DZ, which is the main reason for the difference in the vertical distribution of gas reservoirs between the DZ and FDZ.

Ring‐Moat Dome Structures (RMDSs) in the Lunar Maria: Statistical, Compositional, and Morphological Characterization and Assessment of Theories of Origin

AbstractRing‐moat dome structures (RMDSs) are positive morphologic features found clustered across many mare regions on the Moon, of which only a few isolated examples have been previously reported. Our continuing survey has expanded the known locations of the RMDSs from ~2,600 to over 8,000, indicating that RMDSs are more common geological features than previously thought. This work presents a detailed geomorphological analysis of 532 RMDSs identified in several mare basins. The combination of detailed elemental mapping, morphological and morphometric analyses, spatial distribution relationships with other geologic structures, and comparison with terrestrial analogs lead us to conclude that (1) RMDSs represent low circular mounds with diameters of a few hundred meters (average about 200 m) and a mean height of 3.5 m. The mounds are surrounded by moats ranging from tens to over 100 m in width and up to several meters in depth; (2) there is a wide variation of titanium abundances, although RMDSs are more commonly found in mare regions of moderate‐to‐high titanium content (&gt;3 wt% TiO2); (3) RMDSs are found to occur on or around fractures, graben, and volcanic edifices (small shields and cones); (4) a spatial association between RMDSs and Irregular Mare Patches (see Braden et al., 2014, https://doi.org/10.1038/ngeo2252) is observed, suggesting that both may form from related lava flows; (5) comparisons between RMDSs and lava inflationary structures on Earth support an inflation‐related extrusive nature and a genetic relationship with host lava flow processes; and (6) RMDS embayment relationships with craters of different degradation ages superposed on the host mare, and regolith development models, produces conflicting age relationships and divide theories of RMDS origin into two categories, (1) synchronous with the emplacement and cooling of the host lava flows ~3–4 Ga and (2) emplaced substantially after the host mare lava unit, in the period ~0–3 Ga. We outline the evidence supporting this age conundrum and implications for the different theories of origin and describe future research avenues to help resolve these outstanding questions.