Transition Belt Research Articles

Structural detachment influences the shale gas preservation in the Wufeng-Longmaxi Formation, Northern Guizhou Province

Abstract In order to reveal the restriction in shale gas enrichment of the Wufeng-Longmaxi Formation in the northern Guizhou province, the influence model of detachment layer was established through field geological investigation, core observation, logging, sample analysis, and geological background data. The response relationship between the detachment layer and the shale gas enrichment model in different structural formats was analyzed. The results show that the thickness of the Wufeng-Longmaxi Formation’s detachment layer is influenced by the conditions near the fault zones and mineralogical characteristics. The lithofacies of the detachment layer shows mainly a combination of clay-rich shale facies. This indicates that lithofacies type is one of the main factors influencing the variation in slip layer thickness. The detachment layer exhibits distinct well logging response characteristics and is influenced by nitrogen enrichment. The development of detachment fractures allows atmospheric nitrogen to infiltrate shale gas. It leads to poor gas saturation in the shale gas. In addition, the overall tectonic deformation in the northern Guizhou province was found to gradually intensify from Northwest to Southeast, and there were two tectonic models: a slot-shift tape transition belt and a spacer type deformation belt. The influence of decollements on shale gas preservation was barely found in the northern Guizhou province. It is mainly controlled by buried depth of the target layer, conditions of the cover layer, structural type, and deformation intensity.

A climate-driven, altitudinal transition in rock glacier dynamics detected through integration of geomorphological mapping and synthetic aperture radar interferometry (InSAR)-based kinematics

Abstract. In dry southwestern South Tyrol, Italy, rock glaciers are dominant landforms of the high-mountain cryosphere. Their spatial distribution and degree of activity hold critical information on the current state of discontinuous permafrost and consequently on the response potential to climate warming. Traditional geomorphologic mapping, however, owing to the qualitative expert-based nature, typically displays a high degree of uncertainty and variability among operators with respect to the dynamic classification of intact (permafrost-bearing) and relict (permafrost-devoid) rock glaciers. This limits the reliability of geomorphologic rock glacier inventories for basic and applied purposes. To address this limitation, (i) we conduct a systematic evaluation of the improvements that synthetic aperture radar interferometry (InSAR) can afford to the detection and dynamic classification of rock glaciers and (ii) build an integrated inventory that combines the strengths of geomorphologic- and InSAR-based approaches. To exploit fully InSAR-based information towards a better understanding of the topo-climatic conditions that sustain creeping permafrost, we further explore how velocity and the spatial distribution of moving areas (MAs) within rock glaciers may vary as a function of simple topographic variables known to exert first-order controls on incoming solar radiation, such as elevation and aspect. Starting from a geomorphologic inventory (n=789), we characterize the kinematics of InSAR-based MAs and the relevant hosting rock glaciers on 36 Sentinel-1 interferograms in the 2018–2019 period. With respect to the original inventory, InSAR analysis allowed us to identify 14 previously undetected rock glaciers. Further, it confirmed that 246 (76 %) landforms, originally interpreted as intact, do exhibit detectable movement (i.e., ≥1 cm yr−1) and that 270 (60 %) of the relict labeled counterparts do not, whereas 144 (18 %) were kinematically undefined due to decorrelation. Most importantly, InSAR proved critical for reclassifying 121 (15 %) rock glaciers, clarifying that 41 (13 %) of those interpreted as being intact do not exhibit detectable movement and that 80 (17 %) of the original relict ones do move. Reclassification (i) allowed us to identify a cluster of intact rock glaciers below 2000 m a.s.l. associated with positive mean annual air temperature (MAAT), and (ii) by increasing the altitudinal overlap between intact and relict rock glaciers, it depicts a broad transition belt in the aspect–elevation space, which varies from 50 m on west-facing slopes to 500 m on easterly ones. This finding deteriorates the significance of elevation and aspect as topographic proxies for modeling permafrost occurrence and highlights the importance of using InSAR to inform such models. From a process-oriented standpoint, InSAR information proves fundamental for imaging how this altitudinal transition manifests through changing rates and styles of rock glacier surface deformation. Specifically, we find that, as rock glaciers move faster, an increasingly larger proportion of their surface becomes kinematically involved (i.e., percent MA cover) and that this proportion increases with elevation up to 2600–2800 m, beyond which an inflection occurs and consistent average values are attained. Considering that the inflection falls between the −1 and −2 °C MAAT – the lower boundary for discontinuous permafrost – and is independent of slope gradient, we conclude that this altitudinal pattern represents a geomorphic signature: the dynamic expression of increasing permafrost distribution, from sporadic to discontinuous.

Determinants of pesticides use among tomato farmers in the Bono and Ahafo regions of Ghana

Tomato production plays a crucial role in the livelihoods of farmers and agricultural households in the forest savanna transitional belt of Ghana. However, the success of tomato cultivation is hindered by the presence of insect pests and diseases, necessitating the use of agricultural inputs. This study aimed to identify the pesticides used in tomato farming, assess their World Health Organization (WHO) active ingredient hazard class, determine the precautionary behaviour associated with pesticide use by tomato farmers, and elucidate the socio-economic factors influencing pesticide usage in the Bono and Ahafo regions of Ghana. A multistage sampling procedure was employed to select 1009 respondents, who were administered a structured questionnaire. Descriptive statistics and logistic regression models were used to analyse the collected data. The results revealed that tomato farmers utilized 15 types of insecticides (e.g., lambda and chlorpyrifos ethyl based), 8 types of fungicides (e.g., mancozeb and sulphur + copper based), and 6 types of weedicides (mostly glyphosate based) on their crops. Notably, four insecticides and two fungicides types were found to be unregistered products. Lambda-cyhalothrin-based insecticides and mancozeb-based fungicides were predominantly used by the farmers. The assessed pesticides exhibited varying levels of hazard, ranging from slight to moderate. The study found that farmer training was a significant driver influencing insecticide use, while the educational level of farmers and average yield played important roles in determining fungicide use. Socio-economic factors such as being the head of the household, employing farm workers, the cultivated tomato variety, and farmer training influenced weedicide use. The type of tomato variety cultivated emerged as the primary socio-economic driver of pesticide use. The study recommended the establishment and implementation of a systematic monitoring regime for pesticide product marketing and use, with the aim of reducing the utilization of unregistered products by farmers. Implementing these measures supports sustainable tomato farming in the Bono and Ahafo regions of Ghana.

Crustal Velocity Structure of the Sichuan–Yunnan Block Revealed by High-Quality Crustal Phase Travel Time

Abstract The Sichuan–Yunnan block is located at the southeastern margin of the Tibetan Plateau, which is the key area as a transition belt from the active plate extrusion zone to the stable Yangtze Craton. Using a semiautomatic measuring method based on a graphical interface, we pick 81,585 precise travel times from 449 local earthquake records and finally obtain a crustal 3D P-wave velocity model of the Sichuan–Yunnan block. The model reveals an unexpected velocity contrast between the shallower and deeper crusts. It is summarized as weakly perturbed low-velocity belts encircling a high-velocity zone in the upper crust and strongly perturbed low-velocity anomalies in the mid-lower crust, respectively. The weak low-velocity anomalies are revealed along the major strike-slip faults, and their small perturbations may imply a slip-driven mechanism. The strong low-velocity anomalies are distributed extensively in the Sichuan–Yunnan block, and their great perturbations may be related to the partial melting of weak material extruded from Tibet. Besides, our result shows noticeable high-velocity anomalies in the core zone of the Emeishan Large Igneous Province (ELIP), which may be an indication of magma solidification from the ancient mantle plume. The result further exhibits an interesting pattern that the strong low-velocity anomalies are partially separated by the high-velocity anomalies in the ELIP. Such a specific pattern probably reflects that the stable zone in the ELIP leads to the bifurcation of weak Tibetan material.

Geochemistry and Zircon U–Pb Geochronology of the Wugongshan Granites in the Northwestern Jiangxi Area, China: Implications for the Paleozoic Tectonic Development of South China

The properties of the Caledonian orogeny along the transition belt of the Yangtze and Cathaysia blocks have received much attention in recent years. The widespread Early Paleozoic granites provide critical geological clues for unraveling the tectonic evolution and geodynamic processes of the South China Continent (SCC). Here we present new zircon U–Pb chronology, whole-rock major and trace elements, in situ Hf isotopes for Paleozoic granites, i.e., the Wugongshan granites in the northwest Jiangxi province, and aim to explore the magmatism and properties of the Caledonian orogeny involved in their formation. Our new data show that the Wugongshan granites were emplaced during the Early Silurian Period (442–438 Ma). The Paleozoic Wugongshan granites belong to S-type muscovite-bearing peraluminous granites (MPG) and show a single origin. The Wugongshan granites exhibit negative εHf(t) values (−11.56 to −6.19) and TDM2 model ages of 2148–1809 Ma, indicating their derivation from an ancient crustal source, through partial melting of ancient crustal material. The Wugongshan granitic magmatism is probably being generated in an extensional environment related to an intracontinental orogeny setting. It is inferred that the Paleozoic tectonic–magmatic event in the Wugongshan area was associated with the oceanic–continental convergence of the Paleo-Tethys Ocean. The Wugongshan granites highlight the intracontinental magmatism in the Early Paleozoic orogeny in the SCC.

Study On Fine Injection and Production in the Infill Well Area of A Transition Belt

A transition belt of Daqing oilfield was put into operation in July 2019. The injection and production perfection degree of some well groups is low, the injection-production ratio is unbalanced, the formation energy is insufficient, the yield declines greatly, and the water cut rises quickly.In order to slow down the decline of the block and control the rising speed of water cut, the actual problems existing in the block are discussed. By drawing on the successful adjustment practice of the infill well area of the transitional belt in the B transition belt, the injection and production status and adjustment methods of the infill well area in the transitional belt in A transition belt were studied, two aspects of injection-production system and injection-production structure in block are considered. Different adjustment countermeasures were formulated for oil and water Wells in different strips, and the direction of fine injection and production adjustment was clarified. By using the well focus, structure adjustment and water injection production structure adjustment and so on, effectively reduce the block production decline, control water cut increase speed, and reduce the contradiction between the layers. To realize the purpose of further increase the level of reservoir utilization and improve the development level of A transition belt. At the same time, it provides experience for the injection and production adjustment of the infill well area for the future transition zone.

Scientific and technical problems of transition from open pit to combined technologies for raw materials mining

In Kryvyi Rih iron ore basin, long-term and intensive mining of deposits applying open pit methods have resulted in significant areas disturbed by open pits, dumps and tailings storage facilities. Hundreds of thousands of hectares of fertile arable land are already unsuitable for agriculture and sometimes for living. Thousands of tonnes of dust from dumps and tailing ponds deteriorate the surrounding nature every year and pollute the atmosphere in mining basins. Industrial ore breaking in open pits using bulk blasting causes emissions of a significant amount of harmful dust and carcinogenic substances. The environmental situation in open pit mining areas is often close to critical. In addition, bulk blasting forms a seismic wave, which in some cases destruct civil buildings and industrial facilities. The article proposes ways of gradual transition from mining mineral deposits by open pit methods to environmentally friendly technologies of open pit-underground and underground mining. It is established that such transition is a forced and at the same time choiceless way of developing mining areas, in particular Kryvyi Rih iron ore basin. The paper notes that the main problems of this transition include geomechanical stabilization of the rock massif during construction of underground mines in areas of possible impacts of open pit fields. The paper develops the fundamental study of the problems of controlling the stress-strain state of the massif during transition from the open pit to combined technology of deposit mining. Technologies of combined mining that involve formation of a transition belt with backfilling the worked-out space with compound mixtures are studied as well. It is proved that development of theoretical foundations for controlling the stress-strain state of the massif during transition from the open-pit to combined technology of deposit mining, study and design of technological solutions that contribute to transition to open pit-underground and underground mining, is an urgent scientific, technical and practical problem of great importance.

Petroleum geological features and hydrocarbon enrichment of Linhe Depression in Hetao Basin, NW China

Based on paleogeomorphology, drilling and seismic data, this paper systematically studies the structural and sedimentary evolution, source rock characteristics, reservoir characteristics and formation mechanism, hydrocarbon accumulation model and enrichment law in the Linhe Depression of the Hetao Basin, NW China. The Hetao Basin mainly experienced three stages of evolution, namely, weak extensional fault depression, strong extensional fault depression and strike-slip transformation, giving rise to four positive structural belts (Jilantai, Shabu, Nalinhu and Xinglong), which are favorable areas for oil and gas accumulation. The two main saline lacustrine source rocks, Lower Cretaceous Guyang Formation and Oligocene Linhe Formation, are characterized by high sulfur content, rich algae, early maturity, early expulsion, and wide oil generation window. The large structural transition belt in the intermountain area around the Hetao Basin controls the formation of large-scale braided river delta deposits, which are characterized by high quartz content (50%–76%), long-term shallow burial and weak compaction, low cement content, and good reservoir properties in delta front sandbody. The burial depth of the effective Paleogene reservoirs is predicted to reach 8000 m. Three hydrocarbon accumulation models, nose-uplift near sag, buried hill surrounding sag, fault nose near source rock, are constructed. The law of hydrocarbon accumulation in the Linhe Depression is finally clarified as follows: near-source around the depression is the foundation, high-quality thick reservoir is the premise, good tectonic setting and trap conditions are the key.

Soil Moisture Dynamics and Its Temporal Stability under Different-Aged Caragana korshinskii Shrubs in the Loess Hilly Region of China

Soil moisture has a great influence on vegetation growth and survival in arid and semiarid regions. Information about deep soil moisture dynamics is vital for restoring vegetation and improving land management on the water-limited Loess Plateau. The spatiotemporal dynamics and temporal stability of deep soil moisture (at a soil depth of 600 cm) were observed in situ under Caragana korshinskii shrubs that had various stand ages (named CK-10yr, CK-20yr and CK-35yr) in the Loess hilly region of China. The results showed that under C. korshinskii, soil moisture generally decreased as the stand age rose. Meanwhile, its moisture was consistent with precipitation variation, and an obvious time lag in soil moisture was found compared to that in precipitation during the entire growing season. Along the soil profile, a transition belt linking the shallow with deep soil moisture occurred at a 200 cm soil depth in different slope positions and aspects. At the slope scale, both the slope aspect and slope position significantly affected soil moisture variation in the areas with planted C. korshinskii shrubs, experiencing a decreasing trend from semi-shady slopes to sunny ones and from lower positions to upper ones. However, the variance in soil moisture between different positions and slope aspects was small. For the slope aspect, except for CK-20yr, the different-aged C. korshinskii shrubs had higher soil moisture content on sunny slopes than on semi-shady slopes at the upper 0–200 cm soil depth, while the opposite was true at the 200–600 cm soil depths. For slope positions, the soil moisture variation was small between the 0 and 200 cm soil depths and larger between the 200 and 600 cm soil depths. Within the whole profiles, the representative depth under the C. korshinskii shrubs for the soil moisture content was mainly concentrated between the 400–500 cm soil depths, on average, showing a gradual deepening trend with increasing restoration age. In summary, the findings indicate that natural recovery with low-water consumption grasslands and manual management measures, such as thinning and mowing, should be strengthened to minimize the high soil moisture consumption rates that occur in a healthy soil moisture environment and maintain sustainable vegetation restoration.

The delta-fluvial evolution of a lacustrine basin with gentle slope and low sedimentation rate: A case study of the Fudong Slope, Junggar Basin, Northwest China

Gentle slope belts of lacustrine basins are important areas for the generation of stratigraphic petroleum reservoirs controlled by sedimentary systems. Based on coring, well logging, 3D seismic and analytical test data, the sedimentary system and sandbody distribution characteristics of the Jurassic Toutunhe Formation (J2t) in the Fudong slope of the Junggar Basin were analysed. The results indicated that the Fudong slope showed the characteristics of low sediment input. Sediments mainly originated from the Shaqi uplift, and the sediment input gradually weakened from the early to the late J2t stages. The sedimentary system evolved from a delta to a meandering river, resulting in a delta front facies in the 1st member (J2t1) and a meandering river facies in the 2nd (J2t2) and 3rd (J2t3) members of the Toutunhe Formation. A sedimentary evolution pattern for the gentle slope with low sediment input was established. Thick deltaic sandbodies developed locally in the J2t1 stage. However, meandering rivers with high sinuosities predominantly developed and resulted in a striped geometry in the J2t2 and J2t3 members. Moreover, the meandering sandbodies exhibited an anastomosing morphology after multistage superposition. The channel and point bar facies in J2t2 were more developed than those in J2t3 because of sediment input differences. Under low-sediment input conditions, the sedimentary environment of the gentle slope belt in the lacustrine basin was controlled by changes in the palaeoclimate, palaeogeomorphology, gradient (slope) and base level. Palaeoclimate was the main factor controlling the evolution of the sedimentary environment. Palaeogeomorphology and slope controlled the distribution of sedimentary microfacies, channel sinuosity and sandbodies. Base-level change restricted the sandbody superimposition style. Under the low sediment input conditions of the Fudong slope, the subaqueous distributary channels of the delta environment and the point bars of the meandering river environment in the transitional belt of the Fudong slope are the main potential targets for stratigraphic petroleum reservoirs, whilst the 2nd member of the Toutunhe Formation (J2t2) is the main favourable interval for stratigraphic reservoir exploration.

A clue to the evolutionary history of modern East Asian flora: Insights from phylogeography and diterpenoid alkaloid distribution pattern of the Spiraea japonica complex

Each subkingdom of East Asian flora (EAF) has a unique evolutionary history, but which has rarely been described based on phylogeographic studies of EAF species. The Spiraea japonica L. complex, which is widespread in East Asia (EA), has received considerable attention because of the presence of diterpenoid alkaloids (DAs). It provides a proxy for understanding the genetic diversity and DA distribution patterns of species under various environmental conditions associated with the geological background in EA. In the present study, the plastome and chloroplast/nuclear DNA of 71 populations belonging to the S. japonica complex and its congeners were sequenced, combined with DA identification, environmental analyses, and ecological niche modelling, to investigate their phylogenetic relationships, genetic and DAs distribution patterns, biogeography, and demographic dynamics. An “ampliative” S. japonica complex was put forward, comprising all species of Sect. Calospira Ser. Japonicae, of which three evolutionary units carrying their respective unique types of DAs were identified and associated with the regionalization of EAF (referring to the Hengduan Mountains, central China, and east China). Moreover, a transition belt in central China with its biogeographic significance was revealed by genetic and DA distribution patterns from the perspective of ecological adaptation. The origin and onset differentiation of the “ampliative” S. japonica complex was estimated in the early Miocene (22.01/19.44 Ma). The formation of Japanese populations (6.75 Ma) was facilitated by the land bridge, which subsequently had a fairly stable demographic history. The populations in east China have undergone a founder effect after the Last Glacial Maximum, which may have been promoted by the expansion potential of polyploidization. Overall, the in-situ origin and diversification of the “ampliative” S. japonica complex since the early Miocene is a vertical section of the formation and development of modern EAF and was shaped by the geological history of each subkingdom.

North slope transition zone of Songnan-Baodao sag in Qiongdongnan Basin and its control on medium and large gas fields, South China Sea

Based on analysis of newly collected 3D seismic and drilled well data, the geological structure and fault system of Baodao sag have been systematically examined to figure out characteristics of the transition fault terrace belt and its control on the formation of natural gas reservoirs. The research results show that the Baodao sag has the northern fault terrace belt, central depression belt and southern slope belt developed, among them, the northern fault terrace belt consists of multiple transition fault terrace belts such as Baodao B, A and C from west to east which control the source rocks, traps, reservoirs, oil and gas migration and hydrocarbon enrichment in the Baodao sag. The activity of the main fault of the transition belt in the sedimentary period of Yacheng Formation in the Early Oligocene controlled the hydrocarbon generation kitchen and hydrocarbon generation potential. From west to east, getting closer to the provenance, the transition belt increased in activity strength, thickness of source rock and scale of delta, and had multiple hydrocarbon generation depressions developed. The main fault had local compression under the background of tension and torsion, giving rise to composite traps under the background of large nose structure, and the Baodao A and Baodao C traps to the east are larger than Baodao B trap. Multiple fault terraces controlled the material source input from the uplift area to form large delta sand bodies, and the synthetic transition belt of the west and middle sections and the gentle slope of the east section of the F12 fault in the Baodao A transition belt controlled the input of two major material sources, giving rise to a number of delta lobes in the west and east branches. The large structural ridge formed under the control of the main fault close to the hydrocarbon generation center allows efficient migration and accumulation of oil and gas. The combination mode and active time of the main faults matched well with the natural gas charging period, resulting in the hydrocarbon gas enrichment. Baodao A transition belt is adjacent to Baodao 27, 25 and 21 lows, where large braided river delta deposits supplied by Shenhu uplift provenance develop, and it is characterized by large structural ridges allowing high efficient hydrocarbon accumulation, parallel combination of main faults and early cessation of faulting activity, so it is a favorable area for hydrocarbon gas accumulation. Thick high-quality gas reservoirs have been revealed through drilling, leading to the discovery of the first large-scale gas field in Baodo 21-1 of Baodao sag. This discovery also confirms that the north transition zone of Songnan-Baodao sag has good reservoir forming conditions, and the transition fault terrace belt has great exploration potential eastward.

A mud-dominated coastal plain to lagoon with emerged carbonate mudbanks: The imprint of low-amplitude sea level cycles (mid-Upper Cretaceous, South Iberian Ramp)

The middle Santonian-lower Campanian carbonate-mud dominated succession deposited in the northeastern margin of the South Iberian Ramp (La Cañadilla Fm, NE Spain) shows a complex set of interfingered facies developed in a low-energy and low-gradient shallow-marine to coastal environment. Three facies belts characterize the environment reconstructed in this work: (1) a low-energy shallow marine lagoon dominated by radiolitid rudist limestones and miliolid-rich facies with variable carbonate-mud content; (2) a transitional belt with a patchy distribution of ponds and mudbanks. This belt mostly consists of miliolid-rich limestones with variable amount of fenestral porosity, which are interfingered with charophytes and gastropod marls and limestones usually mixed with miliolids; (3) a coastal plain with strong freshwater influence characterized by the sedimentation of marls and limestones with charophytes, gastropods and root traces and intraclastic/black pebble limestones. The studied succession is arranged in high-frequency sequences, including meter-scale parasequences bounded by widespread flooding surfaces, which stack in five larger-scale shallowing-upward sequences (6–20 m thick). The time calibration of these sequences obtained from strontium isotopes and biostratigraphic data (benthic foraminifera) suggests a major control in the sedimentation by climate-driven low-amplitude sea level oscillations formed in tune with the long- and short-eccentricity orbital cycles. Cyclic sea level rises controlled the existence of widespread flooding events in the low-gradient carbonate ramp at the onset of parasequences, which in the studied marginal areas of the South Iberian Ramp were mostly sourced from the southern Tethyan realm. Therefore, the La Cañadilla Fm provides an example of a complex shallow marine to coastal system giving rise to a mosaic distribution of carbonate-mud dominated facies, with sedimentation mostly influenced by external factors resulting in a well-defined stratigraphic architecture. The similarities with modern analogous systems such as the Ten Thousand Islands of the Florida Bay are discussed in this paper.

Characteristics analysis of drought at multiple spatiotemporal scale and assessment of CMIP6 performance over the Huaihe River Basin

Study regionThe Huaihe River Basin is located in China’s north-south climate transition belt, where massive droughts occurred in history. Study focusTo comprehensively capture how climate extremes have behaved in the past, this paper analyzed the trend, change point, and periodicity of drought at multiple spatial-temporal scales based on the Standardized Precipitation Indexes (SPI). And the historical simulation experiments of 9 CMIP6 models were evaluated against observations for further exploring the behavior of climate extremes in future periods. New hydrological insights for the regionThe period of SPI-12 lies around 2–7 years, while the period of SPI-3 is at the time scale of 1–3 years, indicating potential teleconnections with large-scale climate events. Moreover, MIROC6 and CESM2 models exhibited better performance in simulating precipitation than individual models and multi-model ensemble mean. The uncertainties of the model ensemble mean of 3 selected models in depicting droughts have a good consistency with the observations. The projection experiments of CMIP6 derived from the selected historical simulation models can be used to predict drought in the near future and the far future under different scenarios over the Huaihe River Basin.

Imaging the crustal structure beneath the Yinchuan Basin in the western north China Craton using normalized full gradient and 3D gravity inversion

• The crustal structure beneath the Yinchuan Basin is apparently heterogeneous. • The Yellow River fault is divided into two segments, with the boundary at Yongning. • The primary causative structure of the 1739 Pingluo earthquake is the Yinchuan fault. The Yinchuan Basin is located along the transition belt between the Alxa Massif and Ordos Basin, and is characterised by a complex geological structure. However, several important scientific problems remain unresolved, such as, the causative fault of the 1739 Pingluo Ms 8.0 earthquake. In order to provide new insight into the geodynamic processes, the normalized full gradient (NFG) method and 3-D gravity inversion are utilised to image the crustal structure beneath the Yinchuan Basin in the study. The NFG results indicate that the upper crustal structure is complex, particularly at depths shallower than 20 km. The inversion results infer that the locations of large faults are consistent with the high–low gradient zones in horizontal direction. The integrating NFG and density contrasts imaging results reveal that the south-western boundary of the Ordos Basin is the Yellow River Fault which is divided into two segments with the boundary at Yongning; the East Helanshan and Qingtongxia–Guyuan faults are the south-eastern boundary of the Alxa Massif; the Yinchuan fault is the causative fault of the 1739 event and the focal depth of the event is ∼15 km. These findings provide a scientific basis for studying the crustal dynamics and seismogenic mechanisms of strong earthquakes.

Influence of Wood Husk and CaCO3 on the Mechanical Properties of Nitrile Butadiene Rubber

AbstractNatural fiber reinforced composites have sparked a lot of research and engineering interest in recent decades because of their low density, high specific strength, low cost, lightweight, recyclability, and biodegradability, earning them the title of green composite. Nitrile rubber‐based composites are generally used as elastomers in many industries due to their applications such as O‐rings, gaskets, oil seals, synthetic leather, automotive transition belts, etc. In the present work, in order to enhance the mechanical properties of nitrile rubber, the fillers like CaCO3 and wood husk in five different proportions are added to the NBR matrix. The curing studies, mechanical measurements, and SEM (scanning electron microscopy) analysis are conducted and it is found that the tensile and tear strength of the mixture with the proportion of CaCO3 with 10% and wood husk with 50% is the best combination compared to nitrile rubber gum sample. The tensile strength of the matrix with proportion CaCO3 10% and wood husk 50% has increased around 86.15% and where the tear strength increased around 80.59% compared to the matrix without fillers. SEM analysis reveals the uniform distribution of fillers in the rubber matrix, which is in accordance with mechanical properties. This is a cost‐effective method that consumes less time and is non‐pollutant as if this study uses natural products such as wood husk as the fillers.

Structural control on the 2019 Ridgecrest earthquake from local seismic tomography

We apply local seismic tomography to 159,754 P-wave and 101,751 S-wave arrival times of 5287 local earthquakes to determine 3-D images of P- and S-wave velocity (Vp, Vs), Poisson's ratio (ν) and Vp azimuthal anisotropy in the source zone of the 2019 Ridgecrest earthquake in Southern California. Its big foreshock (M6.4) and mainshock (M7.1) took place in a high-velocity (high-V) and low-velocity (low-V) transition belt. The source zone exhibits significant low-Vs and high-ν anomalies in the lower crust and uppermost mantle, probably reflecting crustal fluids associated with upwelling mantle flow. A high consistency between the seismogenic fault of the 2019 Ridgecrest earthquake and a low-Vs and high-ν anomaly suggests that the fluids in the fault zone affected the rupture process. Fast-velocity directions (FVDs) of Vp azimuthal anisotropy in the upper crust reflect effects of faults and cracks, whereas mineral alignments affect the FVDs in the low-V parts of the lower crust. Dominant NW–SE and E–W FVDs are revealed in the study area, indicating that the Pacific-North American plate relative motion causes the crustal deformation of the study area.

Towards Climate Change Preparedness in the MENA’s Agricultural Sector

The Middle East and North Africa (MENA) represents a substantial area of the terrestrial landmass encompassing several countries and ecosystems. This area is generally drier and warmer compared to the rest of the world, and has extreme resource limitations that are highly vulnerable to a changing climate, geopolitical instability and land degradation. This paper will first identify the nature of climate change in the region by analyzing a downscaled climate data and identifying the hotspots of climate change in MENA. It was found that the climate vulnerability is quite high, with the mean annual temperature increasing by as much as 4–6 degrees towards the end of the century. The nature precipitation under climate change is quite speculative, with the Maghreb region showing the highest vulnerability. Based on these results, five action points are postulated that may be implemented to rapidly progress our understanding of climate vulnerability and enhance the climate change preparedness in MENA’s agri-food sector, to take necessary actions to adapt to a changing climate with a systemic resilience perspective. These include working towards: (1) enhancing the sustainability of the rainfed-desert transitional belt (Rangelands) in the MENA; (2) enhancing the sustainability of agri-food systems in the food baskets of MENA and (3) working towards fostering a collective intelligence to support climate change research in the MENA. (4) The need for foresight advice on resilient food systems under climate change and (5) the need for transformative policies for stabilization and reconstruction under climate change.

Pipe comb-tooth damage model caused by nozzle diversion block

Side perforated nozzles reducing diameter, subjected to variable-pressure fluids, become vulnerable components, during controlling the fluid direction and dispersion in industrial spray equipment. The damage behavior of certain 405 stainless steel nozzles was evaluated with the proposed damage model, self-excited flow parameter fluctuations causing comb-tooth damage model. The nozzle inner bottom and adjacent wall of the diversion cone were expanded as a nearly-circular section groove with dense parallel micro-ditches and an adjacent bright transition belt above the expanded groove. The investigation suggests a separation design of the oblique diversion deflecting and section reducing for avoiding this model damage.

Microstructural characteristics, mechanical properties and interfacial formation mechanism of tungsten alloy/steel composite structure fabricated by HIP co-sintering

In this study, tungsten alloy/steel composite structure has been successfully fabricated by co-sintering method using hot isotactic pressing (HIP). The microstructure and mechanical properties of co-sintered samples were investigated systematically. Experimental results show that dense co-sintered base materials were obtained with good tensile properties (870 MPa for 90 W-4.2Ni-1.8Fe-4Cu alloy and 1350 MPa for 30CrMnSiNi2A steel). The co-sintered joint contains five regions: the W alloy matrix, the diffusion-affected zone of the W alloy (η-carbides contain Fe3W3C and Fe6W6C), the reaction interlayer, the diffusion-affected zone of the steel ((Ni, Fe, Cu) solid solution), and the steel matrix. The interlayer shows solidification structure, which is composed of Fe0.64Ni0.36, Cu0.81Ni0.19, Fe3W3C and Fe2W Laves phases. The η-carbides transitional belt with thickness of 4–6 μm formed along the W grain boundaries at the interfacial region between W alloy and interlayer, which is the weakest area of the interface according to the TEM and nanoindentation test results. Furthermore, the formation mechanism of the interfacial structure is deeply discussed. The interfacial shear and tensile strengths of the co-sintered specimen is 310 MPa and 148 MPa, respectively. This technique provides a reliable method of efficient preparation of tungsten alloy/steel composite structure.