Regional Folding Research Articles

Type II topoisomerases shape multi-scale 3D chromatin folding in regions of positive supercoils.

Type II topoisomerases (TOP2s) resolve torsional stress accumulated during various cellular processes and are enriched at chromatin loop anchors and topologically associated domain (TAD) boundaries, where, when trapped, can lead to genomic instability promoting the formation of oncogenic fusions. Whether TOP2s relieve topological constraints at these positions and/or participate in 3D chromosome folding remains unclear. Here, we combine 3D genomics, imaging, and GapRUN, a method for the genome-wide profiling of positive supercoiling, to assess the role of TOP2s in shaping chromosome organization in human cells. Acute TOP2 depletion led to the emergence of new, large-scale contacts at the boundaries between active, positively supercoiled, and lamina-associated domains. TOP2-dependent changes at the higher-order chromatin folding were accompanied by remodeling of chromatin-nuclear lamina interactions and of gene expression, while at the chromatin loop level, TOP2 depletion predominantly remodeled transcriptionally anchored, positively supercoiled loops. We propose that TOP2s act as a fine regulator of chromosome folding at multiple scales.

Silurian ocean island basalt magmatism and Devonian−Carboniferous polymetamorphism: 100 million years in the Western Blue Ridge, USA

The tectonic configuration and evolution of southern Appalachian orogenic episodes are constrained, to a large extent, by knowledge of the timing and environment of pre- or syn-orogenic sediment deposition along with their subsequent thermal and deformational histories. The orogenic events that gave rise to regional folding and Barrovian metamorphism of the Western Blue Ridge (WBR) terrane are a classic example. We present new U-Pb and 40Ar-39Ar results bearing on the timing of magmatism and subsequent metamorphism of the Marble Hill Hornblende Schist (MHHS) of the WBR (southeastern USA). The schist is a key marker unit in the Murphy synclinorium, a central structure in the tectonic configuration of the WBR. The MMHS originated as basaltic volcanics overlying the Murphy Marble at the base of the Mineral Bluff Group. Ocean island basalt geochemistry and a zircon U-Pb age of ca. 437 Ma for the MHHS is consistent with plume-related volcanism in a Silurian remnant ocean basin of the Iapetus Ocean. Hornblende 40Ar-39Ar and rutile U-Pb ages for the MHHS are ca. 380−340 Ma and ca. 320 Ma, respectively, and record subsequent amphibolite facies metamorphism during Devonian Acadian orogeny and the deformation through regional folding and thrusting during the Carboniferous Alleghanian orogeny. The new age constraints for the MHHS require that “isograds” mapped in the region of the Murphy Belt are actually polymetamorphic mineral distributions that developed at least in part through post-Silurian tectonic events.

Prevention of diaper rash in newborns and children under 1 year old: results of a clinical study

Introduction. Modern preventive measures of skin diseases aim to maintain the protective skin barrier. The area that comes in direct contact with the diaper becomes excessively wet, the corneous layer is damaged, which results in a weakened barrier function of the epidermis and the occurrence of an inflammatory process, diaper dermatitis.Aim. To study the clinical efficacy and safety of the use of disposable diapers and pull up pants in full-term and premature infants from birth to 1 year of age to prevent diaper dermatitis.Materials and methods. A total of 45 full-term and premature children under 1 year old with various diseases, including skin eruptions in the area covered by the diaper were included in the study. The proposed care products were used for 14 days on the strict condition that they would be reapplied after defecation and during hygiene procedures in a timely manner. The skin status was assessed visually by a paediatrician from Day 1 to 14 of the study using the M. Odio skin assessment scale.Results. The M. Odio scale evaluation of the skin around waist, buttocks, genitals, anal region, and inguinal folds in all children on Days 1, 7 and 14 showed 0 scores. No adverse events were reported during assessment of the skin status over 14 days of the use of care products.Discussion. The observations were consistent with the previously published data demonstrating that maintenance of the functional characteristics of the skin in the area covered by the diaper and exposed to faecal and urinary enzymes, elevated temperature and humidity prevented the development of diaper dermatitis and skin diseases.Conclusion. No signs of diaper dermatitis were detected in all 45 full-term and premature children under 1 year old, including children with various diseases, during 2 weeks of application of disposable Tanoshi Premium diapers and pull up pants in clinical practice. This fact proves the safety and good tolerance of disposable diapers by children under 1 year old provided that the skin care requirements were met. Tanoshi Premium diapers and pull up pants can be recommended for babies of different ages and body weights, including those with diaper dermatitis.

The structures control the evolution of molasse basins and alteration zones occurrences in the northwestern sector of the Central Eastern Desert of Egypt

Integration between the analyses of both fieldwork and remote sensing dataset were employed to assess the structural evolution of molasse basins and explore gold mineral deposits in the El Qash area, Central Eastern Desert of Egypt. Sandstone, mudstones, wacke, and pebbly conglomerates make up most of the sediments in the molasse basins. The younger basins (595–575 Ma) are small, less weathered, and mostly Dokhan detritus-filled basins compared to the larger older basins (> 625–605 Ma), which have more weathered sources mainly of arc metavolcanics. The molasse basins appear to have originated in a north–south regional extensional setting, characterized by a prolonged period of left-lateral transtension combined with the formation of NNE-trending synformal folds during an ENE–WSW compression phase. Notably, en-echelon arrays of normal faults, oriented perpendicular to the boundary of the strike-slip shear zone, are a recurring feature in basins formed through transtension. Furthermore, oblique NE-SW compression played a role in generating SW-dipping thrust faults and regional folding with NW–SE orientation, along with the reactivation of transtensional normal faults in a reverse manner. Multispectral satellite imagery data and radar data are used to map the relevant lithological units, structures, and hydrothermal alteration zones. This study concludes that the regions where gold deposits may be explored in connection with prospecting alteration minerals include the area around the ophiolitic assemblages, and the granitic intrusions, in addition to the felsite and the molasse sediments contacts.

Kinematic analysis of the Caçapava do Sul Granitic Complex, southern Brazil: Ediacaran syntectonic magmatism and strain partitioning during inclined ductile extrusion along a transpressional shear zone, Dom Feliciano Belt

The Caçapava do Sul Granitic Complex is a ca. 30 km-long syntectonic batholith emplaced at 580-560 Ma along the N–S to NNE-SSW striking Caçapava do Sul Shear Zone, configuring the core of a double-plunging regional asymmetric antiformal fold, with the Passo Feio Metamorphic Complex metavolcanosedimentary wallrocks occurring at the fold limbs. Structural mapping and kinematic analysis along its whole margins allowed to subdivide the granite complex into seven structural domains, each with its own geometric characteristics and kinematics. The observed microstructures included abundant K-feldspar and plagioclase porphyroclasts with asymmetric recrystallization tails, S–C and S–C–C’ fabrics, and more rarely synmagmatic fractures and asymmetrically developed myrmekites. In general, high temperature microstructures are abundant in the southern half of the granitic complex, while these features are overprinted by low temperature brittle-ductile to brittle microstructures in its northern half. The Southern Domain presents foliations with medium angle dip towards the south, high rake lineation towards the SSW and normal shear sense indicators. The Northwestern and Southwestern domains present mainly subvertical N–S striking foliations with sub-horizontal lineations mostly plunging towards SSW and abundant sinistral shear sense indicators. On the other hand, Southeastern and Santos Ferreira domains presents predominantly NE-SW striking foliations with variably dip and sub-horizontal lineations with abundant dextral shear sense indicators. The Northeastern Domain presents low angle foliation dipping towards the NE, which is also locally described in the Southeastern Domain. Dominantly normal movement with top to NE is described in the Northeastern Domain, also locally reported in the Southeastern Domain. The Northern Domain presents low-angle foliation dipping towards the N, with high rake lineation. No shear sense indicator was observed in the Northern Domain due to brittle deformation overprint, but normal kinematics is inferred. The opposite kinematics of the distinct Caçapava do Sul Shear Zone margins are corroborated by punctual data from the Passo Feio Metamorphic Complex rocks. This is compatibilized by the resultant syntectonic granite flow towards N/NE, which is interpreted in a model of oblique transpression with inclined ductile extrusion. The model suggests that transpression of the middle crust had an important pure shear component which was effectively partitioned into structural domains along the Caçapava do Sul Shear Zone in consequence of post-collisional syntectonic magmatism, and coexisted with extensional tectonics in the upper crust (Camaquã Basin) through a detachment along the brittle-ductile transition.

Sulfide Remobilization in the Metamorphosed Kayad Sedimentary Exhalative Zn-Pb Deposit, Western India: Evidence from Mode of Occurrence, Texture, Hydrothermal Alteration Features, and Trace Element Chemistry

Abstract The Kayad Zn-Pb deposit, situated within the Proterozoic Aravalli-Delhi fold belt in western India, is primarily characterized by sphalerite and galena along with pyrrhotite and chalcopyrite. The mineralization occurs as disseminated ores in quartzite, disseminated/laminated and massive ores in quartz-mica schist, and in pegmatite and quartz veins. The laminated ores conform to the regional schistosity and folding, whereas the massive Zn-Pb ores postdate the pervasive tectonic fabric, accumulating at the fold hinges. The massive ore is characterized by durchbewegung texture, discrete blebs of galena and chalcopyrite in a sphalerite matrix with low interfacial angles, and discrete intergrowths of sulfides and sulfosalts such as pyrargyrite, gudmundite, Ag-tetrahedrite, and breithauptite. Geochemical analyses of sulfides reveal microinclusions of sulfosalts comprising Ag, Sb, Cu, Tl, and As, which are regarded as low-melting chalcophile elements (LMCEs). Hydrothermal alteration is insignificant in the laminated and massive ores but prominent around Fe-Cu ± Zn-Pb and Zn-Pb ± Fe-Cu veins. The alteration assemblages in these veins evince a pervasive K + Na ± Fe alteration, later overprinted by a subsidiary Ca ± Na alteration. We interpret the laminated/disseminated ores to be of syndiagenetic sedimentary-exhalative (SedEx) origin formed within an euxinic basin. Conversely, the textural features, mineralogical composition, lack of associated hydrothermal alterations, and evident structural influence on the emplacement of the massive ores suggest they have been remobilized both via plastic flow and by sulfide partial melting. Temperature estimates of up to 650°C, derived from Ti-in-biotite geothermometry of the metamorphosed host rocks, indicate lower-middle amphibolite facies conditions during regional metamorphism. The initiation of melting at these temperatures was promoted by the desulfurization of pyrite to pyrrhotite in quartz-mica schist, aided by melting point depression due to the presence of LMCEs like Ag, Sb, and As.

High-cycle folding fatigue mechanics of a bistable composite tape-spring

A bistable composite tape-spring (CTS) is a thin-walled open slit tube, which can be coiled or folded into two stable configurations. The CTS has been applied to roll-out-solar-array and successfully launched to space station and micro-satellites based on their one-time deployment performance. There is growing interest on CTS to be applied in reversible deployable structures and foldable mechanical hinges; however, its high-cycle fatigue under large shape folding is still unknown. Here, we device a novel folding fatigue setup to investigate the folding-unfolding cyclic behaviour of the CTS. This is achieved by using a bespoke folding fatigue rig, where both the tape ends of the CTS were clamped separately on rotatable shafts to enable folding under cyclic axial displacements. Since stress concentration is more significant in the snapping fold region, analysis is focused on the peak fatigue stress. It is found that the folding peak stress decreases with the folding cycle: although progressive local damage is observed during 3000 to 100,000 cycles, the CTS is still functional and tends to be stablised after 300,000 folding cycles. The Basquin’s law is applied to predict the fatigue life of the CTS, indicating a fatigue life of 1.4E11 folding cycles with a 40% decrease in peak folding stress. These findings are expected to facilitate the structural designs and applications of the CTS to flexible composite hinges.

Conjugate shear model for emplacement of mid-crustal plutons during dextral transpression, southern Nova Scotia, Canada: tectonic and petrological consequences

The South Mountain Batholith (SMB) is a syn-tectonic composite batholith emplaced in the upper crust within the Meguma terrane between 380 and 370 Ma during the later stages of the Neoacadian orogeny. Coeval plutons in southern Nova Scotia are surrounded by mid-crustal (∼4 kbar) andalusite–staurolite aureoles and are discordant to northeast-trending, regional Neoacadian folds. Detailed field studies, combined with published results, indicate emplacement within a dextral transpressional regime during the transition from distributed (D1) to focused heterogeneous strain (D2), which provided vertical conduits that facilitated magma ascent. The Port Mouton Pluton intruded along P-orientated crustal-scale fractures as a series of subvertical granitic sheets, which were progressively rotated and folded with ongoing dextral shearing. By contrast, the Barrington Passage Pluton intruded between crustal-scale, antithetic (sinistral) P-shear fractures and spread laterally between them as pulsed increments to form a layered, subhorizontal, and sill-like complex resembling the laccolithic structure of the SMB. The SMB was emplaced below the Meguma Supergroup, with magma derived from underthrust Avalon terrane and Silurian Rockville Notch Group. The lack of mantle components in the SMB suggests transpressional orogenesis facilitated conductive crustal heating without significant mantle addition, consistent with low p-wave velocities of Meguma lower crust. 400–355 Ma zircons, recorded either as inherited grains in granites or in felsic granulite xenoliths, imply the Neoacadian thermal anomaly extended for 45 Ma, but magmatism represented only ∼40% of that perturbation.

Behavior of organic matter and gold under conditions of folding deformations

He article provides a brief overview of publications on natural organic matter (OM) and its transformation at various stages of the sedimentary rocks conversion. It is demonstrated, that the changes in the composition, structure, and properties of OM were accompanied by changes in the concentration of metals, including gold. The OM and gold behavior under conditions of folding deformations was examined by the authors on the example of the formation of zones of intense folding in large gold-mining regions of Russia (Central Kolyma and Baikal-Patom). Plastic deformations of sedimentary rocks are associated with active migration of gold in the composition of soluble OM components. The squeezing and injection structures that arise during the folding ensured the natural multidirectional movement of OM of the lowest viscosity into the areas of decompaction of sedimentary rocks. This migration resulted in anomalous concentrations of gold and OM in the locking parts of the folds. This process was intensely manifested in the terrigenous-shale rock sequence within the Dekdekan zone of folded dislocations (Central Kolyma region), where gold-bitumen mineralization was identified, represented by a large lens-shaped deposit 500–800 × 2500 m in size. The only metal concentrator here is oil-like bitumen forming very fine dissemination in the rock.

Discriminating Superimposed Alteration Associated with Epigenetic Base and Precious Metal Vein Systems in the Rouyn-Noranda Mining District, Quebec; Implications for Exploration in Ancient Volcanic Districts

Abstract The Rouyn-Noranda mining district of Quebec contains 20 Cu-Zn (±Au ±Ag) volcanogenic massive sulfide (VMS) deposits, including the giant and gold-rich Quemont and Horne deposits. Mineralized epigenetic veins are also present, but their origin and relative timing remain enigmatic. The nature and extent of their alteration signatures and the effect of their superposition on district-scale alteration patterns is unknown. The VMS-related quartz-sulfide Cu-Zn-Ag veins have δ18Oquartz values of 8.5 ± 0.8‰, reflecting δ18Ofluid compositions of –0.4 to 3.1‰ (250°–350°C) that are typical of Archean seawater. They are associated with a proximal Fe-rich chlorite alteration and marginal spotted sericite-chlorite alteration with whole-rock δ18O values of 2.9 to 5.9‰ and are interpreted to have formed within the structurally controlled discordant upflow zones of a VMS hydrothermal system. Younger gold-bearing quartz-carbonate veins were emplaced along mechanical anisotropies created by mafic dikes during north-south compression and the formation of regional E-trending faults, folds, and cleavage. They are characterized by δ18Oquartz values of 11.3 ± 0.8‰, reflecting δ18Ofluid compositions of 2.4 to 5.9‰ (250°–350°C), typical of a metamorphic fluid, possibly mixed with a lower δ18O upper crustal fluid. They are associated with ankerite, calcite, muscovite, chlorite, albite, and quartz ± hematite alteration with whole-rock δ18O values of 5.8 to 10.3‰. Chemical abrasion-isotope dilution-thermal ionization mass spectrometry (CA-ID-TIMS) U-Pb zircon ages for two tonalite intrusions constrain the maximum age of the Cu-Zn-Ag veins to 2697.6 ± 0.7 Ma and the minimum age to 2695.3 ± 1.0 Ma, which is also the maximum age of the gold quartz-carbonate veins. Superposition of alteration related to the gold quartz-carbonate veins on previously chlorite- and sericite-altered rocks has resulted in mixed alteration signals with whole-rock δ18O values of ~6 to 8‰ that have perturbed and masked regional alteration patterns related to older VMS mineralization, such as those found in the Quemont and Horne deposits. These results indicate that defining alteration vectors in camps that have superimposed hydrothermal systems requires full consideration of the hydrothermal history of the camp, and if such constraints are lacking, whole-rock δ18O values should not be used as a stand-alone exploration method.

Variation in base composition, structure-function relationships, and origins of structural repetition in bacterial rpsA gene

Protein domain repeats are known to arise due to tandem duplications of internal genes. However, the understanding of the underlying mechanisms of this process is incomplete. The goal of this work was to investigate the mechanism of occurrence of repeat expansion based on studying the sequences of 1324 rpsA genes of bacterial S1 ribosomal proteins containing different numbers of S1 structural domains. The rpsA gene encodes ribosomal S1 protein, which is essential for cell viability as it interacts with both mRNA and proteins. Gene ontology (GO) analysis of S1 domains in ribosomal S1 proteins revealed that bacterial protein sequences in S1 mainly have 3 types of molecular functions: RNA binding activity, nucleic acid activity, and ribosome structural component. Our results show that the maximum value of rpsA gene identity for full-length proteins was found for S1 proteins containing six structural domains (58%). Analysis of consensus sequences showed that parts of the rpsA gene encoding separate S1 domains have no a strictly repetitive structure between groups containing different numbers of S1 domains. At the same time, gene regions encoding some conserved residues that form the RNA-binding site remain conserved. The detected phylogenetic similarity suggests that the proposed fold of the rpsA translation initiation region of Escherichia coli has functional value and is important for translational control of rpsA gene expression in other bacterial phyla, but not only in gamma Proteobacteria.

Transpression or polyphase deformation along craton margins: Insights from the Archean–Proterozoic boundary near Sudbury, Canada

Continental margins vary in composition and configuration, resulting in complex structural geometries during deformation. One example is the Archean–Proterozoic boundary near Sudbury, Canada, where the Creighton-Victoria Deformation Zone (CVDZ) contains both reverse dip-slip and dextral strike-slip kinematic indicators. To resolve if these structures formed during a single transpression event or multiple overprinting events, the orientation, relative timing and style of the CVDZ are compared to those of adjacent regional structures. Regional fold axes and their axial planar foliation are subparallel to the steeply-plunging stretching lineation and steeply-dipping foliation, respectively, along the CVDZ. Phase equilibria modelling of syn-tectonic staurolite-chloritoid assemblages indicates that the regional folds and foliation formed at 480–565 °C, similar to temperatures estimated for the formation of dip-slip quartz crystallographic preferred orientations (CPO) along the CVDZ. This suggests that the CVDZ, regional folds and foliation formed during the same regional folding and reverse shearing event. Major lateral lithological changes and inflections in the orientation of the craton margin controlled the formation of structures, and evidence for regional transpression, such as strike-slip kinematic indicators, steeply-plunging stretching lineation, and obliquity of regional folds with respect to major shear zones, resulted from polyphase deformation and transcurrent reactivation of the Superior craton margin.

Digital Videokymography: Analysis of Glottal Closure in Adults.

High-speed videolaryngoscopy and quantitative analysis of laryngeal images are relevant in accurately diagnosing vocal fold closure patterns. To analyze the parameters of digital videokymography obtained through high-speed videolaryngoscopy in women and men with complete and incomplete glottal closure, and posterior glottal chink. We conducted an observational, analytical, cross-sectional study with data from 65 adults, which we divided into groups according to sex and glottal closure. Digital videokymography parameters were analyzed using an image-processing program. The Anderson-Darling and Mann-Whitney U tests were used to verify sample normality and compare videokymography parameters between groups, respectively. The significance level was set at 5%. Among 65 laryngeal images, 20 each were from women with complete and incomplete glottal closure, and 20 and 5 were from men with complete and incomplete glottal closure, respectively. Considering the clinical relevance of the evaluated data, groups of 11 women and 4 men with posterior glottal chink were compared with sex-similar groups with complete glottal closure. Digital videokymography showed a lower maximum and mean vocal fold opening in women with incomplete glottal closure, and a lower dominant left vocal fold-opening amplitude and higher dominant frequency of bilateral vocal fold opening in men with incomplete glottal closure. It also showed a lower closed phase percentage in the posterior region for women and men, with higher closed phase percentage in the anterior and middle regions in women. Both groups with posterior glottal chink showed similar results. Incomplete glottal closure may interfere with the results of the digital videokymography parameters, with higher impact on the posterior vocal fold region in males and the middle and anterior vocal fold regions in females.

An Assessment of the Effectiveness and Safety of ULTRACOL100 as a Device for Restoring Skin in the Nasolabial Fold Region

One of the most notable signs of an aging face is the nasolabial folds (NLFs), which often diminish emotional well-being and self-confidence. To address this concern, many people seek solutions to improve their appearance, often turning to fillers. The ULTRACOL100 device, a tissue restoration material, has been previously investigated and shown to exhibit significant efficacy in both in vitro and in vivo studies. In this research, we aim to explore the safety and effectiveness of the clinical trial of ULTRACOL100 in improving the skin in the NLF area over an 8-week observation period. Male and Female adults with nasolabial folds received two injections of ULTRACOL100, with a 4-week interval between treatments, on one side of their faces. On the other side, they received control materials (REJURAN®, JUVELOOK®, or HYRONT®). The assessment of skin improvement in the nasolabial fold area for each subject took place before and four weeks after each application. Various skin parameters, such as roughness, elasticity, moisture, transparency, trans-epidermal water loss, tone, radiance, skin pore size, and skin density, were measured to evaluate the outcomes. The application of the ULTRACOL100 device significantly reduced the skin roughness, the trans-epidermal water loss, and the skin pore size and increased the skin’s elasticity and internal elasticity, as well as the skin’s moisture, transparency, skin tone, radiance, and density. This study comprehensively investigates the effectiveness and safety of the ULTRACOL100 device, comparing it with three commercial products (REJURAN®, JUVELOOK®, and HYRONT®). The ULTRACOL100 device showed comparable performance in improving the appearance of the NLF area among this study subjects.

Tectonic position of the Ukrainian shield

Statement of the general problem. The analysis of the geological structure of Europe indicates a wide development of Laramian (post-Cretaceous - pre-Cenozoic) deformations in non-Alpine regions. They are traced by the regional angular unconformity between the folded Mesozoic and non-folded Cenozoic from the Caspian Sea to Great Britain. The area of development of the Laramie folding of Europe also covers the Ukrainian shield. An unsolved part of the overall problem. The Ukrainian crystalline shield is described as "uplift of the crystalline foundation of the East European platform", where Precambrian rocks come to the surface. But the same rocks can also be traced far beyond its borders. The question arises - what structural position does the Ukrainian shield occupy in the structure of the Laramie folded region? Analysis of recent research and publications. On the geological maps of the pre-Cenozoic formations of Ukraine, the northern border of the Laramie folded region can be traced along the Chernihiv-Lysychansk line. Mesozoic folds and an angular unconformity in the Cenozoic basement disappear further north. To the south, the Laramie deformations intensify, but unevenly. The purpose of the article is identification of modern structural position of Ukrainian crystalline shield. Research materials and methods. Were involved more than 120 geological maps of Ukrainian regions and author's digital geological model of East Ukraine. Presentation of the main research material. A band of Mesozoic folds and NW vergence thrusts tens to hundreds of kilometers long is developed immediately south of the border of the folded region. The amplitude of the folds is 1.5–2 km. The band of development of these folds and thrusts with a width of about 100 km limits the Ukrainian shield from the northeast. To the south of the Ukrainian Shield, on the shelves of the Black and Azov Seas and in Northern Crimea, a sub-latitude band of Laramie thrusts and folds with a width of 150–200 kilometers has been established. Amplitudes of thrust folds reach 1–2 km, amplitudes of separate thrusts reach 8–10 km. This band of folds and thrusts limits the southern slope of the Ukrainian shield from the south. These Laramie folds and thrusts are overlain by Cenozoic sediments. To the south, in the Mountainous Crimea, the deformations are still intensifying. Folds and thrusts are replaced by wide and extended mélange zones of northwestern vergence. The Ukrainian shield is bypassed by the development of folds and thrusts from the northeast, east, and south. On the slopes of the Ukrainian shield, Mesozoic fold deformations subside, and the Mesozoic there lies gently sloping and monoclinally. Such poorly deformed blocks within folded regions are called middle massifs. This middle massif of the Laramie fold region within Ukraine has an anteclise structure. In the core of the anteclise, Precambrian metamorphic and igneous rocks emerge from under the sedimentary cover. The western wing of the anteclise is overlain by younger thrusts of the Carpathian folded structure of Attic (post-Miocene) age. Scientific novelty. In the modern geological structure, the Ukrainian shield is the core of the anteclise of the middle massif in the Laramie folded region. Conclusions. As a tectonic uplift, shield was formed in the Paleocene. In the Late Cretaceous, it was still buried under shelf carbonate deposits. Erosion of this uplift formed the Cenozoic deposits of Ukraine with a specific mineragenic specialization. Taking into account the Laramian folding allows us to reconcile the diverse geological phenomena of the region into a single system without contradictions.

Shale 3D Flow and Interaction With Basement Faults in the Niger Delta Deep‐Water Fold and Thrust Belt

AbstractBased on a large 3D seismic data set in the deep‐water domain of the Niger Delta, this study challenges previous interpretations involving the occurrence of multiple detachments and extensive thrust flats, illustrating timing and mode of shales flow at the toe of the gravity system. Five units of syn‐kinematic sediments, reaching a maximum thickness of ∼800 m, accumulated in the tectonically subsiding synclines during fold amplification between ∼9.5 and ∼1.4 Ma. The volumes of syn‐kinematic units roughly balance those of the shales accumulated in the thickened cores of WNW trending anticlines. This feature is consistent with folding resulting from buckling controlled by the competence contrast between isopach Cenozoic units and underlying overpressured shales of the Akata Formation. A dense network of NE‐SW striking oblique extensional faults offsets a prominent anticline characterized by a NE‐SW trend (which is almost perpendicular to the regional fold trend). These faults form a narrow, continuous deformation zone extending for tens of kilometers along and beyond the length of the anticline. The faults, rooting within the shales of the Akata Formation, formed since ∼5 Ma and deform the seabed. Displacement distribution suggests mechanical interaction between isolated fault segments within the deformation zone. The latter is interpreted as the shallow expression of a deep‐seated fault zone inherited from the segmented passive margin and marked by gravity and magnetic data. Our results, providing a comprehensive picture of active deformation features and their relationships with deep‐seated faults, shed new light into the modes of interaction between gravity systems and underlying basement structures.

Thermo-tectonic evolution of the Neoarchaean Southern Marginal Zone of the Limpopo granulite Complex (South Africa)

Abstract Combined geophysical, structural geological, metamorphic, geochronological, and stable isotope information is employed to elucidate the Neoarchaean thermo-tectonic evolution of the Southern Marginal Zone (SMZ) within the Limpopo Complex (South Africa) during the Limpopo orogeny (2.72 to 2.62 Ga). The complex evolutionary history of the SMZ was controlled by an allochthonous SMZ granulite nappe that was extruded from a rising granulite diapir through a process of mid-crustal heterogeneous channel flow. This granulite nappe with its embedded structures (steeply plunging reclined folds and steep shear zones) was formed during emplacement of the diapir to mid-crustal level (6 kbar, 20 km depth) from where it was thrust south-westwards along the Hout River shear zone (HRSZ) sole thrust against the Kaapvaal Craton (KVC) at 2.72 to 2.69 Ga. Evidence for the thermo-tectonic interaction of the granulite nappe with the KVC includes (1) thrust complexes (referred to as hot-iron zones) that are developed at the frontal ramp sections of the HRSZ juxtaposed against the granite-greenstone belts of the KVC, and (2) strike-slip shear deformation associated with the lateral ramp section of the HRSZ, which developed against the KVC devoid of greenstone belts. The emplacement of the post-tectonic Matok granitic pluton at ~2.68 Ga into the SMZ signified the end of the thermo-tectonic event that established the regional fold- and shear deformational framework of the granulite facies SMZ. Post-Matok secondary shear zones reflect evidence for HRSZ-linked tectonism that continued intermittently to 2.65 to 2.62 Ga. Low H2O-activity fluids (H2O activity of 0.1 to 0.3) released from devolatilisation of underthrust greenstone material passively infiltrated and interacted with the overlying cooling granulites. This established a retrograde anthophyllite-in isograd at ~6 kbar and ~620°C that subdivides the SMZ into a northern granulite domain and a southern retrograde hydrated granulite domain. Simultaneously, gold-bearing fluids focused into these minor shear zones established shear zone-hosted orogenic gold mineralisation at 2.65 to 2.62 Ga. Emplacement of the post-tectonic Palmietfontein granite at ~2.46 Ga and associated sub-volcanic granitic dykes into both the retrograde hydrated granulite domain and the granulite domain signifies the end of all thermo-tectonic activity in the SMZ. A Palaeoproterozoic thermal overprint at ~2.1 Ga is recorded by Rb-Sr biotite and phlogopite ages derived from various rocks from the SMZ and adjacent KVC. This thermal event is not associated with deformation and did not result in the formation of new mineral assemblages. Integrated data presented and discussed in this paper contradict the interpretation of age and petrological data utilised to support alternative models for the evolution of the SMZ, including a proposed ~2.1 Ga Palaeoproterozoic polymetamorphic amphibolite-grade thermo-tectonic event.

Salt tectonics along the High Zagros Fault in Iran, faulting through welded salt walls

In salt-bearing foreland fold-thrust belts, precursor salt structures affect deformation and accommodate fault zones during orogenic shortening. The complex structure and the halokinetic history of these belts, including the spatiotemporal relationship between diapirism and thrust faulting, have yet to be fully understood. The well-exposed Ediacaran–Early Cambrian Hormuz salt diapirs and the Cambrian–Pliocene overburden stratigraphic sequences along the High Zagros Fault (HZF) in Iran are interesting examples in this regard. The detailed field investigation of the diapirs, the halokinetic deformations, and the thickness variations of the sedimentary units toward the flanks of eight salt structures along the fault show that the first movement of the Hormuz salt could be as old as the Middle Cambrian, occurring long before the initiation of regional folding in the early Miocene. This marks the first field-based and the oldest proposed time for the onset of Hormuz salt diapirism in the Zagros fold-thrust belt. Our field and remote-sensing mapping show the presence of precursor linear salt structures like salt walls. The Hormuz salt diapirs likely began to rise as elongated salt walls above extensional basement faults coeval with the Neo-Tethyan rifting in Early Mesozoic. The squeezing of the salt walls during Zagros shortening from Miocene resulted in the partial accommodation of the HZF as thrust welds. This spatiotemporal evolution, showing the interplay between salt diapirism and late thrusting, can be considered as an analog for other fold-and-thrust belts with pre-orogenic diapiric systems.

Ultra-thin composites membrane for deployable structures: XCT driven characterization and FE modeling of folding structure

Light-weight, ultra-thin, high performance, origami-inspired deployable folding structures can be fabricated by simulating various designs and material combinations. In this study, an XCT-driven finite element (FE) model of a building block in a typical full-scale origami structure consisting of stiff and fold regions was developed. Following our previous work, the stiff region of the fold sample was fabricated using a hot compression molding technique whereas hand layup was employed for the fold region. XCT-driven FE based homogenization was carried out on an RVE of real microstructure of both ultra-thin composite laminates. The FE homogenization results were found to be in good agreement with the experimentally-measured effective stiffness properties of both the stiff and fold regions, with a maximum error of ∼10%. Folding tests were conducted on a simple fold and the force vs. displacement and moment vs. curvature curves were plotted. The applicability of XCT-driven FE modeling to simulate foldable structures were demonstrated using post-buckling and bending analysis available in the FE software ABAQUS®. A uniform and symmetric fold curvature, along with the corresponding force vs. displacement response were predicted using XCT-driven FE techniques and found to be in good agreement with data from the experimental tests. The peak force predicted by the FE model showed an error of ∼5.2% compared to the experimental fold test.

Structural features of thyroglobulin linked to protein trafficking.

Thyroglobulin must pass endoplasmic reticulum (ER) quality control to become secreted for thyroid hormone synthesis. Defective thyroglobulin, blocked in trafficking, can cause hypothyroidism. Thyroglobulin is a large protein (~2750 residues) spanning regions I-II-III plus a C-terminal cholinesterase-like domain. The cholinesterase-like domain functions as an intramolecular chaperone for regions I-II-III, but the folding pathway leading to successful thyroglobulin trafficking remains largely unknown. Here, informed by the recent three-dimensional structure of thyroglobulin as determined by cryo-electron microscopy, we have bioengineered three novel classes of mutants yielding three entirely distinct quality control phenotypes. Specifically, upon expressing recombinant thyroglobulin, we find that first, mutations eliminating a disulfide bond enclosing a 200-amino acid loop in region I have surprisingly little impact on the ability of thyroglobulin to fold to a secretion-competent state. Next, we have identified a mutation on the surface of the cholinesterase-like domain that has no discernible effect on regional folding yet affects contact between distinct regions and thereby triggers impairment in the trafficking of full-length thyroglobulin. Finally, we have probed a conserved disulfide in the cholinesterase-like domain that interferes dramatically with local folding, and this defect then impacts on global folding, blocking the entire thyroglobulin in the ER. These data highlight variants with distinct effects on ER quality control, inhibiting domain-specific folding; folding via regional contact; neither; or both.