Flowers Research Articles

Surface morphology and microstructure of Bauhinia variegata L. flowers and leaves

The main purpose of this research is to characterize the wettability and microstructure of Bauhinia variegata L. flowers and leaves, aiming to provide a biological template for the preparation of hydrophobic surfaces. The contact angle test results show that the surfaces of flowers and leaves are hydrophobic, and the contact angle of the adaxial side and abaxial side of the leaves is highly significant difference, which is mainly affected by the topological morphology of the surface microstructure. The topological structure of flower and leaf surface morphology was revealed by scanning electron microscopy (SEM) and super-depth of field three-dimensional microscope. The results showed that the cell structure of flower surface array was the main factor leading to the hydrophobicity of flowers. The snowflake-like structure on the leaf surface is the main factor leading to hydrophobicity of leaves, and the burr structure of the micro-nano dual-level structure unique to the abaxial side of the leaf further enhances the hydrophobicity of the abaxial side, and the contact angle increases, resulting in a highly significant difference in wettability between the adaxial side and abaxial side. This provides an important biological template and reference value for the preparation of biomimetic materials.

Impact of the Regional Pai-Khoi-Altai Strike-Slip Zone on the Localization of Hydrocarbon Fields in Pre-Jurassic Units of West Siberia

The paper presents the results of a geological interpretation using gravity, magnetic, and seismic data to understand the oil and gas potential of pre-Jurassic sedimentary intervals and basement in the central West Siberia basin. The 200 km long Pai-Khoi-Altai strike-slip zone was investigated. Reconstruction based on a data complex indicate the right-lateral kinematics of the principal strike-slip faults and possible fault inversion. The study evaluated the spatial and genetic relationship between the conditions for hydrocarbon trap development and the strike-slip fault systems, such as “flower structures”. Strike-slip geometry and kinematics are confirmed based on 2D and 3D seismic data. Geological and geophysical criteria are used to forecast localization of hydrocarbon fields. Predictive zones are elongated in several different directions and have a different distribution pattern in the blocks separated by principal strike-slip faults, confirming its significance as a controlling factor for the hydrocarbon potential of the region’s structures.

Cenozoic dextral transpressional tectonics in the northwestern Qaidam Basin, northern Tibet: Evidence from paleomagnetic and kinematic analysis of the arcuate belts

The mechanisms by which complex intracontinental deformation in the northern Tibetan Plateau was accommodated since the India-Asia collision remain debated. Characterization of the formation of arcuate structures in northern Tibet provides important constraints on this debate. We conducted a new paleomagnetic study on the mid- to late Miocene strata along the curved Lenghu-Nanbaxian and Eboliang-Hulushan belts of the Qaidam Basin, northern Tibet. Our results revealed that there is nonsignificant relative rotation within localities along these arcuate belts, which yielded a common mean direction of declination (D) = 3.6°, inclination (I) = 35.7° (α95 = 2.4°) after tilt correction, suggesting negligible Neogene vertical-axis rotation along the arcuate belts in the Qaidam Basin. Outcropped fault striations and the positive flower structures indicate dextral strike-slip−dominated motion along the faults since the mid- to late Miocene. By integrating the paleomagnetic results with the kinematics of these associated faults, we ruled out the possibility that these curved belts formed due to the frictional drag of the Altyn Tagh fault or due to differential shortening across the Qaidam Basin. Instead, we attribute the formation of these nonrotational arcuate belts to dextral transpressional deformation occurring within the basin since the mid- to late Miocene. Different from the orogenic belts in the northern Tibetan Plateau that absorbed postcollisional convergence through block rotation, crustal shortening, and lateral extrusion, the Qaidam Basin has also accommodated significant intracontinental deformation in the northern Tibetan Plateau through transpressional deformation within the basin. This inference underscores the importance of recognizing crustal extrusion within rigid blocks as a record of intracontinental deformation in the northern Tibetan Plateau.

Warm Bulb Storage Optimises Flowering Attributes and Foliage Characteristics in Amaryllis belladonna L.

Amaryllis belladonna is an autumn-flowering bulbous geophyte endemic to the Western Cape, South Africa. The species’ erratic flowering disposition and brief flowering period upon maturity limit its economic productivity and competitiveness within the traditional genera of cut flowers and potted plants. However, it can be an attractive, eco-friendly, seasonal addition to the specialty floriculture market. A 10-month study evaluated the effects of a warm storage period on A. belladonna bulbs’ flowering yield, flowering time, quality characteristics, and foliage growth. The experiment comprised dormant flower-sized bulbs randomly assigned to one of six storage regimes of either a 0- (no storage control), 4-, 6-, 8-, 10-, or 12-week interval periods at a continuous warm temperature of 23 ± 1 °C before planting into pots between mid-November 2021 and mid-February 2022 in the greenhouse. The results showed that flowering production (64.3% flowering after the 12-week storage), flowering time (anthesis occurring 9 days after the 10- and 12-week storage), and quality attributes (number of florets in the inflorescence, scape diameter, inflorescence fullness ratio, and pot longevity) of A. belladonna scapes were significantly impacted by warm bulb storage, but not foliage growth. Irrespective of bulb storage, inflorescence abortion occurred. An extended bulb storage did not advance the flowering time despite a greater harvest and shorter cultivation periods after planting. This study established that a cumulative temperature range during bulb dormancy is crucial for supporting the A. belladonna inflorescence maturity’s energetic demands and the opening of floret buds. Bulbs should be stored at elevated temperatures for at least 8–10 weeks to attain the best floret-quality attributes and longevity. However, for an economical and sustainable greenhouse and specialty cut flower production, 12-week warm bulb storage is recommended to achieve the optimal anthesis in the shortest interval for this seasonal single-harvest species after planting.

Silicon flower structures by maskless plasma etching

Silicon nano/microstructures are widely utilized in the semiconductor industry, and plasma etching is the most prominent method for fabricating silicon nano/microstructures. Among the variety of silicon nano/microstructures, black silicon with light-trapping properties has garnered broad interest from both the scientific and industrial communities. However, the fabrication mechanism of black silicon remains unclear, and the light absorption of black silicon only focuses on the near-infrared region thus far. Herein, we demonstrate that black silicon can be fabricated from individual flower-like silicon microstructures. Using fluorocarbon gases as etchants, silicon flower microstructures have been formed via maskless plasma etching. Black silicon forming from silicon flower microstructures exhibits strong absorption with wavelength from 0.25 μm to 20 μm. The result provides novel insight into the understanding of the plasma etching mechanism in addition to offering further significant practical applications for device manufacturing.

Mixed mating patterns in morphologically diverse bumblebee-pollinated Salvia species from China

Abstract Flowers of Salvia are characterized by a diversity of staminal lever types mediating pollen transfer. In the East Asian subgenus Glutinaria, species have been categorized based on their distinct flower and stamen morphologies. A hypothesized advantage of degraded-lever types suggests they may optimize pollinator foraging time, increase visitation rates, and potentially trigger autonomous self-pollination. However, this hypothesis remains untested. Here, Salvia castanea, S. miltiorrhiza, and S. liguliloba were selected as test species representing the three major flower and stamen types of the East Asian sages. We compared the species with regard to their inflorescence architecture, floral display, nectar reward, pollinator efficiency, and seed set. We found that S. liguliloba had a degraded-lever type that significantly reduced pollinator foraging time did not significantly increase pollination efficiency. These species have a mixed mating pattern with high seed set, no pollen- or pollinator limitation, and no inbreeding depression. We conclude that the diversity of floral traits is addressed to pollinators, whereas reproductive success emerges from a complex interplay of factors encompassing floral characteristics, pollination efficiency, plant life history, or/and other biotic and abiotic factors. For this reason, the link between floral morphological traits and mating systems should not overestimated.

Fault structure, seismicity, and magmatism of the Littoral Fault zone, northern South China sea: Insights from high-resolution seismic reflection data

Four destructive M7+ earthquakes and 18 M6+ earthquakes demonstrate that the Littoral Fault Zone (LFZ) is one of the most seismically active regions in the offshore area of South China. However, the location, geometry, and structural characteristics of the LFZ, which spans over 1000 km, have not been properly examined. In this study, we investigate the precise position of the LFZ offshore East Guangdong (EGD) and map the fault structure using recently acquired high-resolution multi-channel seismic (MCS) reflection data. The LFZ consists of an array of normal faults that collectively form a terraced sidewall fault zone linked to the continental rifting of the South China Sea (SCS). This fault zone is approximately 35–75 km wide and runs parallel to the shoreline. The primary faults of the LFZ EGD segment correlate to a high-gravity gradient zone and serve as the northern boundary of the Zhu-I Depression. During the syn-rift phase, the LFZ experienced significant intra-plate deformation, resulting in fault throws of up to 1000 m. This deformation was locally influenced by pre-existing structures, giving rise to a listric geometry at depth. In the post-rift period, the LFZ exhibited inherited activity along its rift-related faults. The presence of growth fault structures suggests that the LFZ remained active throughout the Cenozoic, with numerous active faults extending practically to the seafloor. The negative flower structure confirms the strike-slip character of the LFZ, which is influenced by the modern tectonic stress field. Intense multi-phase Cenozoic magmatism, including igneous intrusion, volcanism, and lava flows, has been detected in the offshore area of Nan'ao Island. The frequent earthquakes in the study area are primarily attributed to far-field stress release resulting from the subduction of the Philippine Sea Plate beneath the Eurasian Plate. Additionally, the intense magmatism weakens crustal structures, further facilitating stress release and the frequent occurrence of earthquakes.

Slip partitioning and seismogenic stress buildup adjacent to the junction of the Lenglongling fault and the Tuolaishan fault: Insights from kinematically constrained numerical simulations

Understanding fault kinematics plays a crucial role in estimating seismic hazards and linking the relationship between seismogenic stress buildup and tectonic deformation. The northwestern segment of the Qilian-Haiyuan fault zone (QHFZ) serves as a natural laboratory for investigating how the oblique block motion decomposes into a complex fault system. In this study, we constructed a 3D FEM model incorporating the active faults as contact discontinuities to obtain a continuous numerical image of fault slip rates. Our findings revealed that deformation partitioning within the context of oblique block convergence generates a spatially heterogeneous distribution of fault slip rates. The inferred strike-slip rates of the Tuolaishan fault and the Lenglongling fault (LLLF) range from approximately 2 to 4 mm/yr and 4 to 7 mm/yr, respectively. The Lenglongling fault's slip behavior exhibits a spatial transition, with a dominant strike-slip component dominating in the western part and gradually changing to a combination of reverse faulting and strike-slip in the eastern segment. The Northern Lenglongling fault (NLLLF), characterized by a listric shape, merges with the LLLF in the deep crust, resulting in the formation of a positive flower structure that enhances the accumulation of compressional seismogenic stress. The region with high shear strain rates within this area has experienced significant earthquakes, including the 2022 Menyuan MS 6.9 earthquake, the 2016 Menyuan MS 6.4 earthquake, and the 1986 Menyuan MS 6.4 earthquake. Our numerical study gained valuable insights into the relationship between slip partitioning, fault structures, and regional stress.

Surface rupturing earthquakes along the eastern Rhine Graben Boundary Fault near Ettlingen-Oberweier (Germany)

The eastern Rhine Graben Boundary Fault (eastern RGBF) forms the eastern margin of the Upper Rhine Graben (URG), the most seismically active area in the plate interiors of Europe. Despite seismic activity posing a significant threat to the densely populated URG and critical facilities therein, only a few studies have documented the paleoearthquake history and associated seismic hazard, focusing mainly on the western margin. We present the results of the first paleoseismological trenching ever conducted on the central section of the eastern RGBF. Following high-resolution near-surface geophysical studies, we excavated six trenches near Ettlingen-Oberweier (south of Karlsruhe, Germany) on one of its secondary fault strands. The nearly-vertical fault is transtensional left-lateral and splits into several NNW-SSE en échelon branches, forming a negative flower structure. Stratigraphic and structural relationships along with radiocarbon and Optically Stimulated Luminescence dating reveal a minimum of three surface-rupturing paleoearthquakes with a Mw of potentially 6.5 ± 0.5, occurring from old to young, >56 ka (EX), between 54 and 19 ka (EY), and between 15 and 1 ka (EZ). The events are poorly constrained in age due to erosional unconformities. Based on the cumulative vertical separation of 1.2 ± 0.3 m, we calculate an average vertical slip rate of 0.02 ± 0.005 mm/yr. From a horizontally offset alluvial channel, we infer a cumulative left-lateral slip of 5.9 ± 0.7 m and derive an average horizontal slip rate of 0.1 ± 0.01 mm/yr. The average net slip rate is 0.1 ± 0.02 mm/yr for the past 59.5 ± 3.8 ka. This value represents a minimum slip rate for the eastern RGBF, considering slip distribution within the different fault strands of the fault system. Our findings highlight the seismic potential of the eastern RGBF, providing new evidence of the Late Pleistocene and Holocene tectonic activity of its central section.

PSIV-5 High Desert Hemp Varieties Under Varied Nitrogen Fermentation Techniques Effects on Its Utilization as Livestock Feed Through in Vitro Fermentation

Abstract Nitrogen fertilizing of hemp varietals in high the high desert may assist in ensuring that production levels match the demand for growing hemp varietals. However, altering fertilizer levels may differently affect plant biomass and cannabinoid concentrations of plant tissues which changes the potential by-product utilizable for livestock feed. This study aimed to determine the influence of hemp fractions [flower (FL) vs stem and leaves (SL)] under three nitrogen fertilization regimens (0, 100, and 200 kg· ha-1) on in vitro rumen fermentation. Incubations runs consisted of triplicates of 500-mL bottles containing approximately 0.5 g of either ground SL or FL of hemp at the three nitrogen fertilization regimens. Rumen fluid was collected from two ruminally cannulated Angus steers, filtered through four layers of cheesecloth, and diluted to 4:1 with a standard buffer solution. A total incubation volume of 75 mL of the buffer: rumen fluid mix was added to each flask. Flasks were then placed in a rotating incubator (55 rpm) at 39°C, connected to an Ankom RF gas production system (Ankom Technology, Macedon, NY), and removed after 24, 48, and 96h. Total gas production (TGP), metabolizable energy (ME), ammonia nitrogen concentration (N-NH3), and total volatile fatty acids (VFA) were determined. Data were analyzed as a completely randomized design using lmer function in lme4 package in R with treatment and time as a fixed effect and replicates as a random effect. Statistical significance was established at P < 0.05 (Table 1). No differences were observed for N-NH3 (P > 0.05). Overall, SL samples had greater total VFA than FL, with T0SL having the greatest concentration among all treatments (P < 0.01). In congruence, acetate, isobutyrate, isovalerate, and the ratio between acetate and propionate concentrations were also greater for T0SL (P < 0.01). Concentrations of butyrate were greater for T200SL (P < 0.01), while T100SL had the greatest concentration of butyrate among all the treatments (P < 0.01). Overall, SL fractions of hemp seem to be more suitable as a ruminant feed source. The greater fat content of the FL compared with SL may detrimentally affect microbial populations and should further be explored. From our results, N supplementation significantly alters fermentation patterns during in vitro, which further warrants the evaluation of these feeds on in vivo experiments.

Coseismic and early postseismic deformation associated with the January 2022 Mw 6.6 Menyuan earthquake, NE Tibet, revealed by InSAR Observations

The 7 January 2022 Mw 6.6 Menyuan earthquake struck the Qilian-Haiyuan fault zone, NE Tibet, offering a chance for understanding the regional seismogenic structure and rupture behavior. We use Interferometric synthetic aperture radar data to study the coseismic and early postseismic deformation of the event. Coseismic modelling highlights that the earthquake activated two strike-variable high-angle strike-slip faults (one SE-trending main fault and one ENE-striking secondary fault) corresponding to only part of the Lenglongling and Tuolaishan faults. Further postseismic analysis not only reveals a localized postseismic signal of up to ∼3 cm related to the mainshock but identifies an obvious coseismic signal of up to ∼2.3 cm associated with an MW 5.1 aftershock characterized by sinistral strike-slip-faulting. The 2022 Menyuan earthquake, large aftershock and 2016 Mw 5.9 thrust-faulting Menyuan earthquake illuminate a positive flower structure of the Lenglongling fault. By a joint analysis of the inversions, fault kinematics and historical earthquake, we suggest that fault branches and low pre-stress jointly restrain the maximum rupture size in the 2022 Menyuan event.

Design of a nature-inspired sun-tracking device in context of rural India

The efficiency of the photovoltaic system is traditionally being increased with the help of solar concentrators. The concentrators based on biomimetic structures of various flowers have proven to be effective in increasing performance efficiency. The present study proposes the design of a nature-inspired, novel and passive, single-axis solar tracker that operates on the principle of variable coefficients of thermal expansions of different metals in a bimetallic plate. The proposition mimics the heliotropism mechanism of Sunflowers to achieve acceptable results. It involves the use of a solar PV panel mounted on a gear assembly, connected to a bimetallic plate via connecting linkage and a concave mirror to reflect the incident sun rays on the plates during the day. The resultant deflection in the plates rotates the mounted solar PV panel to follow the sun throughout its diurnal course. There were certain conditions that were determined mathematically to ensure correct working of the proposed design. CAD modelling was adopted to better study the functioning of the envisioned contraption as a whole. The proposed design is easy to construct; thereby making it an efficient, promising and economical alternative to other passive and fixed ones.

3D-printing of biomass furan-based polyesters with robust mechanical performance and shape memory property

3D-printing provides a feasible technique for realizing new materials into structural and intelligent parts. In this work, biomass furan-based polyesters poly (ethylene furanoate) (PEF), poly (trimethylene furanoate) (PTF), and poly (butylene furanoate) (PBF) were successfully synthesized in a 5 L reactor through the melt polycondensation process and fabricated into 3D-printing feedstocks. It was demonstrated that the three furan-based polyesters were additively-manufactured into complicated structures. Besides, the mechanical and thermal properties of furan-based polyesters could be tailored by the chain length of diol monomer. The mechanical performance of 3D-printed PEF, PTF and PBF were characterized and compared with commercial filaments. The tensile strength of PEF and PTF could reach 74.6 and 63.8 MPa respectively, which exhibited superior tensile property to poly(ether-ether-ketone) (PEEK), polyamide (PA) and polylactic acid (PLA). Meanwhile, the compression results demonstrated that the PEF and PTF possessed comparable energy absorption capacity with PEEK and PLA respectively, which indicated excellent mechanical properties of furan-based polyesters. It was interesting to find that the 3D-printed structures including solid cube, bionic flower and lattice structures were employed to prove that the PTF possessed excellent shape memory properties. Therefore, the proposed biomass furan-based polymers would offer more freedom in the field of 3D-printing.

Sorghum straw carbon assisted preparation of thin-sheet like BiOCl with boosted photocatalytic activity toward detoxification of three contaminants

In this work, a one-pot hydrothermal method was employed to fabricate sorghum straw carbon (SSC) modified BiOCl catalysts. SSC not only operates as a template agent to regulate the microscopic morphology of BiOCl to form thinner lamellar structures but also constructs oxygen vacancies (OVs), which together enhance the photocatalytic ability. The samples were researched by Brunauer-Emmett-Teller (BET), X-ray diffractometer (XRD) and scanning electron microscope (SEM). Addition of SSC induce BiOCl to form a flower spherical-like structure assembled by thin sheets. Surface photovoltage spectroscopy (SPS) and electrochemical experiments confirm that the dense interlayer stacking provides more pathways for the separation of charges from bulk to the surface, and the thinner sheet thickness shortens the separation time for the charges, boosting the activity of the photocatalysts. The existence of the main reactive radicals (O2– and h+) in the photocatalytic system was investigated by trapping experiments. Photocatalytic activity of the samples was assessed by destruction of rhodamine B (RhB), tetracycline (TC) and perfluorooctanoic acid (PFOA). When the mass ratio of SSC/BiOCl is 0.75%, the catalyst shows the best photocatalytic activity. A reasonable photocatalytic enhancement mechanism was proposed in combination with the observation results.

The controls of strike-slip faults on fracture systems: Insights from 3D seismic data in the central Tarim Basin, northwest China

The central Tarim Basin has gained wide attention for its petroleum reserves, especially the recent commercial discovery of carbonate reservoirs of the Ordovician age in the Shunbei oil and gas field. A systematic analysis is conducted based on 3D seismic interpretation in the central Tarim Basin. The results indicate the presence of several major strike-slip faults and associated fracture systems. The characteristics of major strike-slip faults indicate a lower positive or negative flower structure in the Lower-Middle Ordovician and faults with a normal sense of movement in the Upper Ordovician due to the regional stress field. The major strike-slip faults commonly cause fractures in multiple scales. The fracture systems in different segments of major strike-slip faults contain significant differences in characteristics. In addition, two models are established with regard to strike-slip fault-associated fracture systems in a compressional setting and an extensional setting. The development of fracture systems varies to a large extent in relation to the scales of a strike-slip fractured zone. The fracture systems in a small-scale shear zone or strike-slip fractured zone usually develop along the fracture plane. In contrast, the fracture systems in a large-scale strike-slip fractured zone commonly develop along the fault zone on both sides.

Controllable deformation design for 4D-printed active composite structure: Optimization, simulation, and experimental verification

Through integrating active composites and 4D printing techniques, active composites can achieve the pre-designed complex deformations. However, the tremendous design space of multiple materials brings the challenges of finding the optimum material distributions accurately, and the consistencies between simulated optimum results and actual experimental structures. Therefore, the controllable deformation design framework is proposed to guide the inverse design of 4D-printed active composite structure. The material properties of polylactic acid (PLA) and thermoplastic polyurethane (TPU) are tested and integrated into forward deformation analysis to improve the prediction accuracy of finite element analysis (FEA). An optimization integration framework with genetic algorithm is developed to optimize the material distribution and external displacement simultaneously to achieve the target deformation. Several voxelized beams and flower structures are used as engineering cases. The simulated and experimental deformation shapes and recovery shapes for the optimum structures are consistent with the target deformations. The mean squared errors (MSEs) of experimental shape and simulation shape are 0.62 mm and 0.27 mm for flower structures. These results show that the proposed methodology can obtain target deformation in simulation and experimental tests simultaneously, which can be applied into the flexible deformation design of complex active composite structures in the future.

Community-wide patterns in pollen and ovule production, their ratio (P/O), and other floral traits along an elevation gradient in southwestern China

BackgroundAs the male and female gametophytes of flowering plants, pollen and ovules largely determine the upper and lower boundaries of plant reproductive success. It is commonly predicted that pollen and ovule number per flower should increase, and pollen-ovule ratio (P/O) per flower should decrease with increasing elevation in response to a more stochastic pollination environment. Here, we aimed to determine the response of pollen number, ovule number, and P/O to other floral traits and elevation gradients for 84 insect-pollinated herbaceous flowering plant species in five sub-alpine and alpine communities (2709 to 3896 m a.s.l.) on Yulong Snow Mountain, southwestern China.ResultsSix floral traits, including P/O, floral display area, flower number, tube depth, flower shape, and pollen presentation, were highly correlated with pollen and ovule number per flower. With increasing elevation, pollen number and P/O per flower increased marginally and significantly, respectively; ovule number per individual, flower number per individual, stigma stamen separation, and inflorescence height decreased significantly. However, ovule number per flower and other floral traits (i.e., floral display area, tube depth, stigma height, stamen height, and pollen and P/O per individual) did not change with elevation. We detected significant phylogenetic signals for pollen number, ovule number, and P/O, suggesting that these traits may be highly conserved and with limited response to changing environmental conditions.ConclusionsResults revealed patterns of plant reproductive character evolution along elevation gradients and the potential factors governing their spatial variation in high-elevation environments. Plant species at high elevations are more likely adapted to cross-pollination, indicated by increased P/O per flower at high elevations on Yulong Mountain. Combined effects of phylogenetic history and plant-pollinator interactions should determine plant trait evolution.

The seductive choreography of space: Learning regenerative design strategies from (cyborg) flowers

Unlike traditional net-zero emissions approaches, regenerative methods not only manage resources efficiently but also invigorate the environment. Architects focusing on regenerative design can draw inspiration from flowering plants, whose exceptional spatial strategies exemplify the choreography of ecosystem interactions that sustain fertility. The paper introduces the concept of “XENO,” an artistic installation comprising a robotic carnivorous plant, a mosquito, and a microbially-powered fuel cell, exhibited at CIVA, Brussels in 2023. This installation serves as an epistemic object, exploring complex energy system diversity, ethics, and interactions. XENO’s cyborgian elements encapsulate the intricate relationships and energy flows present in ecological architecture, highlighting the ethical concerns that exceed conventional eco-friendly practices, to explore life and death cycles, microbial decomposition, and material transformation within ecosystems — all of which form the basis for new life. In this way, flower structures provide a creative lens for ecological architects to integrate scientific knowledge, societal values, and experience design in ways that foster diverse and ethically resonant energy exchanges that contribute to a more balanced and environmentally conscious future.

Mesozoic strike-slip fault system at the margin of the Junggar Basin, NW China

The Junggar Basin in Northwest China is covered by thick sediments, causing challenges in recognizing buried structures. Seismic reflection and drilling data from petroleum exploration provide essential data for the study of subsurface structures. In this study, we focus on the Mesozoic structural characteristics and tectonic evolution along the margins of the Junggar Basin by using 2D and 3D seismic reflection, drilling data, and surface geology. Our results demonstrate that a unified dextral strike-slip fault system developed along the marginal area around the Junggar Basin. The structural style is characterized by both transpressional structures, such as positive flower structures, en echelon folds, restraining bends, and fan-shaped and horsetail fractures at the fault tip, and transtensional structures, including releasing bends, pull-apart basins (fault basins), and positive inverted structures. We further interpret that except for the southern margin of the Junggar Basin, the current structural pattern of the basin margin was mainly formed in the pre-Cretaceous, which was covered by Cretaceous and Cenozoic strata. Based on the timing and style of deformation, we propose that the vertical-axis counterclockwise rotation of the Junggar Basin during the Mesozoic caused right-lateral strike-slip faulting along the basin margin. Cenozoic reactivation of these structures has been localized in the southern margin of the Junggar Basin under the far-field influence of the India-Asia collision.

Reactivated fracture-controlled uranium mineralization: An example from NNE-SSW Kamaguttapalle–Kammapalle tract, Kadapa district, Andhra Pradesh, India

The Cuddapah Basin (CB) and its basement can be considered as an appropriate uranium metallogenic province. The basement complex of CB in the Eastern Dharwar Craton (EDC), India, has been the target for structurally controlled uranium exploration since the early 1980s. Most of the brittle-ductile deformation induced reactivated narrow linear fracture zones often exhibit significant surface and sub-surface uranium occurrence. There are about 10 fracture zones associated with uranium mineralization. Amongst them, the Kamaguttapalle–Kammapalle fracture zone (KKF) in the south of the CB is quite interesting from an exploration viewpoint with a suitable geologic setting in space and time frame. Geomorphic, structural and petro-mineralogic exploration guides imply the possibility of economic uranium concentration along the NNE-SSW trend where tectonic reactivation took place over pre-existing ductile shear zone. Progressive exhumation and transition from ductile to brittle deformation regime led to the development of dominant strike slip tectonics with an associated riedel fracture system, which are subsidiary coeval shear fractures used in depicting sense of movement. Intense illitization and hematitization are often observed. Quartz reefs and veins along the NNE-SSW trend cut the preexisting mylonites at places. About 9 stages of fracturing is observed out of which 3 stages are related to uranium mineralization. All the 9 deformations are related to strike slip tectonics which in turn is part of Grenville orogeny. Paragenetic sequence and mode of occurrences of uranium phases deciphers about the importance of low to moderate level epi‑meso type hydrothermal (100°–250 °C) fluids as carrier of U. Reactivated fractures and quartz veination also act as controlling factors of mineralization. Strain analysis points to positive and negative flower structures at different segments of the fracture zone. Based on the litho-structural attributes it is established that maximum compression (σ1) acted along the NNW-SSE direction. Fractured quartz veins provide well defined permeability and trapping facility by restricting transverse fluid movement as a mechanical barrier. The presented model gives an idea on role of strike-slip tectonics in uranium mineralization for narrowing down the target zone for sub-surface exploration.