Thrust Planes Research Articles

Thrust system, flower structures and transpressive duplexes in Zeidun-Kareim Belt, Central Tectonic Province, Egyptian Nubian Shield (East African Orogen)

In this study, we explore thrust system, flower structures and transpressive duplexes in the Zeidun-Kareim belt (ZKB) in the Egyptian Nubian Shield (ENS; northwestern ANS). Filed observations and the measured stretched lineations along thrust planes reveal two main thrusting directions; ESE- (to NE- and NNE-)- and NW- (to WNW-)-directions belonging to two main phases of contraction. The timing of both phases is indirectly constrained. The older ESE- (to NE- and NNE-)-vergent thrusting is attributed to the E-W Gondwana assembly. The younger NW- (to WNW-)-vergent thrusting is akin to the Najd Orogeny. The poles to the in-sequence thrusts lie close to the poles of stretching lineations. The mean orientations of thrust propagation are, respectively, 059° and 309°. Propagation of thrusting along the two main thrusting directions resulted in the formation of a complete geometry of thrust duplex system, imbricate nappe stacking, flower structures and thrust-related folding. The top-to- ESE- (to NE- and NNE-) transpression reflects dextral sense, whereas the top-to- NW- (to WNW-) transpression exhibits sinistral sense, in compatible with those recorded and argued by many authors elsewhere in the ENS and the entire ANS. Our study fully constraints the ZKB spathio-temporal tectonic evolution which involves three main stages.

Structural analysis and evolution of large Venusian coronae: Insights from low-angle faults at coronae rims

We analyzed topography, fracture patterns, and faults of the asymmetric Atahensik Corona (700 × 900 km diameter), formerly known as Latona Corona, and their surrounding troughs using Magellan SAR imagery, and compare the results with the smaller, ovoid Didilia (400 × 450 km diameter) and Pavlova coronae (550 × 650 km diameter) to get insights on corona formation on Venus. Atahensik contains a high density of radial, oblique, and concentric fractures, the latter are inferred to be the youngest fractures. A high density of concentric fractures particularly occurs along the outer rise and indicates elastic downward bending of this part of the lithosphere in the later stage of corona formation. Along the steep inner slopes of Atahensik's arcuate troughs, large-scale faults are exposed that dip gently towards the corona center and crosscut all fractures. We propose that these low-angle faults were initially formed as thrust planes but subsequently became reactivated as low-angle normal faults, thereby exposing parts of their fault surfaces. Such faults have been identified not only along the arcuate troughs of Atahensik but also occur in Dali Chasma, northwest of Atahensik Corona.A phenomenological formation model of large coronae is presented: corona initiation starts with radial fracturing, which is caused by the dike emplacement and thermal uplift of the corona center due to the rise of a hot asthenospheric mantle plume. Uplift and lateral plume spreading steepen the outer rim of the uplift and cause intense radial fracturing of a central volcanic edifice and the corona's outer rim. This intermediate stage is preserved in several less-evolved coronae such as Didilia and Pavlova Coronae. The fractured ridge thrusts outward onto an intact and cooler lithosphere along strongly localized thrust planes. The overthrusted, cooler lithosphere is elastically bent downward and forms arcuate troughs and associated outer rises with numerous concentric fractures along their crest line. The fractured ridge annulus of the corona is supported by the intact and thickened lithosphere surrounding the corona. The present morphology of Atahensik Corona indicates subsequent subsidence in its central part due to declining plume activity and reduced thermal buoyancy. Reactivation of the thrusts as low-angle normal faults results from the subsidence of the corona interior, a gravitational instability of the elevated corona annulus, and a lack of shortening. The evolutionary sequence derived on the basis of structural data is in agreement with geodynamic models on corona formation involving a bending lithosphere at the plume margin.

Carbonatization and silicification of ophiolitic ultramafic rocks and formation of gold-bearing listvenites in the Arabian-Nubian shield: A case study from the Al-Barramiya district

Late Neoproterozoic mantle section in the Gabal Al-Barramiya area, the northwestern corner of the Arabian-Nubian Shield (ANS), contains variably serpentinized peridotites that are highly altered along shear zones and thrust planes to form gold-bearing listvenites. They can be categorized into carbonate listvenite, silica-carbonate listvenite and silica listvenite (birbirite). Carbonate listvenite is characterized by the presence of schistosity and deformation fabrics similar to the host serpentinites, but such fabrics are absent in the silica-carbonate and silica listvenites, suggesting that they postdate carbonate listvenite and serpentinization. The presence of listvenites along shears zones and the presence of relics of serpentine and Cr-spinel reflects their formation through metasomatism of ultramafic rocks by hydrothermal fluids circulating along the thrust faults. Silica-carbonate listvenite is characterized by the presence of fuchsite and is enriched in Zn, Pb, Cu, Ag, and Au. Rare earth element (REE) contents differ between the studied listvenites. Silica -carbonate listvenite has the lowest total REE (∑₌0.98–2.56 ppm), whereas the silica listvenite contains the highest total of REE (∑ ₌ 15.70–21.42 ppm). Based on the above, carbonate listvenite is the earliest to form by the infiltration of CO2–bearing fluids released during serpentinization of the original fore-arc peridotite slab, followed by formation of silica-carbonate listvenite due to the activities of SiO2–saturation and CO2-bearing fluids released during ophiolite obduction. Fuchsite in silica-carbonate listvenite formed as a result of metasomatic reactions of Si- and K-rich fluids with Cr-spinel due to hydrothermal alteration of serpentinized peridotite. Silica listvenite formed at the final stage by the silicification of the early formed silica-carbonate listvenite. Listvenitization of the mantle section of the Al-Barramiya ophiolite led to concentration of Au, Pb, Zn, Cu and Ag. The silica-carbonate listvenite contains higher concentration of gold (899–2199 ppb) than the carbonate listvenite (119–191 ppb) and silica listvenite (156–233 ppb).

Garnet Geochemistry of Pertek Skarns (Tunceli, Turkey) and U-Pb Age Findings

The Fe skarn and vein-type Cu mineralization types are common in the Eastern Taurus Mountains. This study aims to determine the U-Pb geochronology of garnets of varying sizes within the skarn zone developed at the quartz diorite–marble contact zone in Ayazpınar, Pertek District, Tunceli Province, Turkey. Additionally, this study aims to determine the age of the skarnization and the types of inclusion minerals in the garnets. Faulting and magma emplacement along the thrust plane caused mineralization in the Eastern Taurus Mountains, especially at the marble and quartz diorite contact zone between the cities of Elazığ and Tunceli. The greenish garnets found in the Ayazpınar deposit are characteristic of distal skarns, while red or brown Pertek garnets are observed in the proximal skarns. The garnets typically feature a core–rim texture. The cores of the garnet crystals are large, reddish in color, and have a high REE (Ce, Pr) content. Moreover, the cores have higher Fe and lower Al ratios, alongside higher La, Ce, and Pr contents, than the rims. We propose that the compositional differences between the rims and the cores reflect the transition from oxidized REE- and Fe3+-rich liquids to liquids with lower REE and Fe3+ contents, producing the differences in the garnet colors. Green garnets show lower REE contents than brown garnets with Fe-rich cores. The skarn under study includes the following successively formed zones: diorite → epidote skarn → garnet–magnetite → pyrite–garnet–magnetite → calcite carbonate. Diopside, magnetite, and hematite, including small grains, are surrounded or enveloped by garnets. The U-Pb age of the mineralization is 74.1 ± 5 Ma, indicating that the mineralization occurred concurrently with the intrusion settlement.

Spatiotemporal Characteristics of Tectonic Tremors in the Collisional Orogen of Taiwan

AbstractTaiwan offers a distinctive tectonic setting as a collisional orogen, ideal for studying tectonic tremors and the slow deformation process in the mountain‐building process. Using continuous seismic data at many stations, which have become available recently, and employing the envelope correlation method, we detected ∼7,000 tremor events from 2012 to 2022, with waveform characteristics similar to tectonic tremors worldwide. Beyond the previously known tremor zone beneath the southern Central Range, where newly detected tremors align along a low‐angle thrust plane, we identified several new tremor “hotspots” spanning 200 km along the mountain belt. These hotspots are situated at the termination of the subducting slabs and around the deep (25–50 km) extension of the Central Range fault, where repeating earthquakes occur at a depth of 10–25 km. Our findings suggest a strong linkage between the tremor generation mechanism and the mountain‐building process, potentially influenced by underground fluid and temperature anomalies.

Gold and sulfide-bearing listvenite in the mantle section of the Tays ophiolite in the Arabian Shield, Saudi Arabia

The mantle section of the Late Neoproterozoic Tays ophiolite in the Arabian Shield consists principally of thoroughly serpentinized peridotite with characteristics typical of depleted mantle protoliths from a fore-arc environment. The serpentinite is altered along shear zones and thrust planes to gold-bearing listvenite bodies of various sizes. These bodies are divided into carbonate listvenite and silica‑carbonate listvenite; they may be dyke-like or lenticular in form, and are yellowish-brown, reddish-brown, or greyish in outcrop. Carbonate listvenite expresses schistose deformation fabrics concordant to fabric in the host serpentinite, whereas silica‑carbonate listvenite is undeformed at field scale and contains a generation of undeformed minerals at thin-section scale. Silica‑carbonate listvenite contains Cr-rich muscovite (fuchsite) and base-metal sulfides and is enriched in Zn, Pb, Cu, Ag, and Au along with SiO2. The transformation of serpentinite along shear zones to different types of listvenite reflects successive episodes of fluid-mediated metasomatism. Carbonate listvenite develops first, driven by infiltration of CO2–bearing fluids during serpentinization of the original fore-arc peridotite. Silica‑carbonate listvenite marks a later episode associated with infiltration of K-bearing, SiO2-saturated fluids released during emplacement of the ophiolite. Listvenitization in the Tays serpentinite concentrated gold in sub-economic to economic extents, with concentrations increasing from host serpentinite (2–4 ng/g) to carbonate listvenite (267–937 ng/g) to silica‑carbonate listvenite (1717–3324 ng/g).

Geophysical and structural analyses of the Middlesboro impact structure, Kentucky, USA: Reactivation of a thrust detachment of the Appalachian foreland fold‐and‐thrust belt

AbstractThis paper reports on the Middlesboro impact structure (36°37′03″ N; 83°43′39″ W), a complex impact structure located in the Appalachian foreland fold‐and‐thrust belt of southeast Kentucky, USA. The structure forms a basin approximately 5.5 km in diameter exposing intensely deformed Pennsylvanian sediments. Based on field data, microstructural observation, and geophysical analyses we qualitatively assess degree and distribution of fragmentation of target rocks within the impact structure. Shock deformation features, especially feather features, are reported for the impact structure. Shallow seismic refraction data were acquired along a radial profile from outside the impact structure to the center of the structure. Seismic (P‐wave) velocity trends indicate that fracture intensity increases toward the center, reducing the overall seismic velocity. However, intense rock sealing in some parts of the central uplift increases the strength of rock samples and locally increases seismic velocities. We present a modified geologic map of the Middlesboro impact structure based on high‐resolution lineament analysis, field work, and reevaluation of existing structural data from geologic maps. The modified map suggests that crater circularity at Middlesboro is skewed by the reactivation of pre‐existing zones of structural anisotropy in the target. We propose that due to an oblique impact from northerly direction the sub‐horizontal Pine Mountain thrust plane beneath the impact structure became reactivated with a top‐to‐the south shear component. The impact‐induced formation/reactivation of the Doublings Fault Zone as a thrust ramp appears to have deflected the otherwise straight strike of the Cumberland Mountains southward. The Rocky Face fault approaches the crater rim fault, and we propose that this sinistral strike‐slip fault was formed, or at least reactivated, by the impact and accommodated the oblique impact's horizontal momentum.

Oxygen Isotopes of Iron Oxides as a Diagnostic Tool for Iron Formation-Hosted High-Grade Magnetite-Hematite Deposits

Coarse-grained granoblastic magnetite-hematite and sheared platy hematite iron orebodies comprise several small deposits (5 to 30 Mt each) on the eastern margin of the São Francisco Craton, bordering the Ediacaran–Cambrian Brasiliano Orogenic belt. Three main mineralization stages are associated with the Brasiliano Orogeny: (1) syn- to the late-collisional stage (ca. 580–560 Ma) with development of lens-shaped schistose orebodies along thrust planes. (2) late- to the post-collisional stage (ca. 560–530 Ma) with the formation of massive magnetite bodies by contact metamorphic-metasomatism with pegmatite. (3) Post-tectonic stage with crystallization of granular hematite associated with late pegmatite (ca. 530–490 Ma). In order to better evaluate the fluid oxygen signature of each mineralization stage, new oxygen isotopes measurements were performed on ore bodies associated with the three stages. These stages are followed by changes in the oxygen isotope signature, with a progressive decrease of the δ18O from the iron formation (1.7 to 8.1‰) to high-grade ore (-1.6 to 2.6‰) that appears to be a common aspect of the mineralization of iron formations. In the present cases, magmatic fluids (δ18O from 4.6 to 13.1‰) have imprinted a relatively “heavier” signature than the most hypogene iron formation high-grade ores worldwide that was progressively modified by meteoric water percolated along extensional fractures. The iron oxides from the contact zones of pegmatitic yielded intermediate δ18O values (1.8 to 5.0‰), indicating a higher magmatic fluid/rock ratio.

Cooling glaciers in a warming climate since the Little Ice Age at Qaanaaq, northwest Kalaallit Nunaat (Greenland)

AbstractThe centennial response of land‐terminating glaciers in Greenland to climate change is largely unknown. Yet, such information is important to understand ongoing changes and for projecting the future evolution of Arctic subpolar glaciers, meltwater runoff, and sediment fluxes. This paper analyses the topography, geomorphology, and sedimentology of prominent moraine ridges and the proglacial areas of ice cap outlet glaciers on the Qaanaaq peninsula (Piulip Nunaa). We determine geometric changes of glaciers since the neoglacial maximum; the Little Ice Age (LIA), and we compare glacier behaviour during the LIA with that of the present day. There has been very little change in the rate of volume loss of each outlet glacier since the LIA compared with the rate between 2000 and 2019. However, the percentage of each glacier that is likely composed of cold‐based ice has increased since the LIA, typically by 20%. The LIA moraines comprise subrounded, striated, and faceted clasts that evidence subglacial transport, and outwash plains, flutes, kames, and eskers that evidence subglacial motion and meltwater within temperate ice. Contrastingly, contemporary ice margins and their convex ice surfaces comprise pronounced primary foliation, ephemeral supraglacial drainage, sediment drapes from thrust plane fractures, and an absence of open crevasses and moulins. These calculations and observations together lead us to interpret that these outlet glaciers have transitioned towards an increasingly cold‐based thermal regime despite a warming regional climate. Thermal regime transitions control glacier dynamics and therefore should be incorporated into glacier evolution models, especially where polythermal glaciers prevail and where climate is changing rapidly.

A multi-scale approach to the recent activity of the Stradella thrust in the seismotectonic context of the Emilia Arc (northwestern Italy)

The frontal thrusts and folds of the northern Apennines - Italy - are mainly covered under the alluvial deposits of the Po Plain. Some of these structures show geological evidence of Late Quaternary activity, thus posing the need for an accurate seismic hazard assessment due to widespread housing settlements, industries, lifeline infrastructures, and large towns. We present new morphostructural, geophysical, and seismological data to discuss the recent activity of the Broni-Sarmato fault, an 18 km-long outcropping section of the north-verging Stradella thrust, located 50 km south of Milan, along the Pede-Apennine thrust front (PTF) in the rear of the Emilia Arc thrust system. The new geoelectrical surveys across the fault scarp show deformation of the shallow deposits. The outcropping deformations, with a fault scarp ranging up to 25.8 m, are investigated within the seismotectonic framework of the PTF and the Emilia Arc. The analysis of the associated seismicity and new focal mechanisms highlight two seismogenic contractional volumes dipping at low-angle southwest-ward, at upper (<12 km) and lower crustal depths (~20–30 km). The shallow seismicity partially illuminates the Stradella thrust and its along-strike southeastward prosecution along the extent of the Stradella-Salsomaggiore Arc. Subordinately, it also illuminates some of the Emilia Arc thrust planes. The deeper seismogenic volume shows large patches of the basal thrust of the Emilia Arc fault system. We interpret the above multi-scale data as evidence of ongoing tectonic activity of the outer fronts of the Emilia Arc under a regional NNE-oriented compressional stress field, with some evidence of thrust involvement along the Pede-Apennine front. In our 3D fault-model reconstruction, all the analyzed thrust structures appear as expressions of a thick-skinned deformation that controls earthquake release at different structural levels.

Negative structural inversion: an overview

The same sense movement on any given fault plane occurs much more frequently compared to the cases when the sense reverses. Therefore, positive or negative structural inversions are regarded as special cases within the much more general and typical process of fault reactivation.Extensional reactivation of former reverse faults or, specifically thrust planes in thrust fold belts, designated as “negative inversion”, received much less attention by both the petroleum industry and the academia than the opposite process.Based on the structural review of many case studies of positive and negative inversion they display contrasting kinematic patterns. One of the obvious structural differences is related to the geometry of short-cut structures developed during the more advanced stage of inversion. In the case of positive inversion, a short-cut thrust develops within the footwall of the major inverted fault to better accommodate the ongoing shortening. In contrast, a short-cut normal fault develops within the hanging wall of the partially inverted master fault during negative inversion.Based on a worldwide compilation there are examples of hydrocarbon fields with valid traps associated with negative inversion. Therefore, we suggest that even though negative inversion may not be as important for petroleum exploration as its positive counterpart, yet, it may produce more traps in the internal parts of thrust fold belt than currently perceived.At present, case studies of negative inversion defined by the extensional reactivation of pre-existing thrust planes are relatively rare, compared to the more frequent documentation of positive structural inversion in published literature. Whether this disparity between negative and positive inversion is a result of non-observation in the subsurface, at the expense of the former, or it is caused by a more fundamental structural difference between the two processes, it remains to be seen.

The 26 November 2019 Durrës earthquake, Albania: coseismic displacements and occurrence of slow slip events in the year following the earthquake

SUMMARYOuter Albanides experienced a seismic sequence starting on 21 September 2019, with an Mw 5.6 earthquake, considered a foreshock, and culminated with the main shock on 26 November 2019, followed by a paramount aftershock activity. We propose a model for the coseismic slip distribution using InSAR, permanent, and campaign GNSS measurements. We tested two hypotheses: an earthquake on a thrust plane with the direction N160° and along with a back thrust. By varying the depth and dip angle for the first hypothesis and only the dip angle for the second hypothesis, we concluded the optimal solution is a blind thrust at a 15-km depth dipping eastward 40°, a maximum slip of 1.4 m and an Mw 6.38. A GNSS time-series obtained after 2020 shows two slow slip events (SSEs): the first one is 200 d after the main shock up to 26 d, and the second one is 300 d after the main shock up to 28 d. We tested three hypotheses: SSE along the basement thrust where the main shock has been localized, SSE along the flat formed by the detachment layer of the cover, and SSE along these two faults. We concluded that SSE occurred along the detachment layer or along the two faults.

The atypical Gaoligong orocline: Its geodynamic origin and evolution

Various orocline systems around the India–Eurasia collision zone have long been recognized and studied. Different portions of the India–Eurasia boundaries represent various scales and models of orocline-forming processes, such as the Baluchistan orocline formed by multiple deformation events and the Himalayan orocline formed by a mixture of complex structural mechanisms. The curvature from the eastern Himalayan syntaxis through east Burma to west Yunnan showed a unique convex curvature toward the mantle wedge. This is different from the concave Baluchistan orocline and the Himalayan orocline. The unique geometry of the Gaoligong orocline shows an N-S trend for the northern section and a NE-SW trend for the southern section. This curvature also marks the boundary between the Tengchong and Baoshan blocks along the Santaishan suture in western Yunnan, China. Our structural reconstruction identified five deformation events: 1) D1 is km-scale upright folding, which only affected the Neoproterozoic meta-sedimentary unit, 2) D2 recumbent folding, which only developed in the southern section of the Gaoligong orocline, 3) D3 large-scale gently westward-inclined thrust folding, 4) D4 right-lateral shear belt, and 5) the D5 normal faults. Since the D3 structure is the earliest event that shows penetrative foliation development along the orocline, we consider D1 and D2 as pre-orocline-forming events. The geometry of the Gaoligong orocline is controlled by the distribution of the Ordovician basement between the Tengchong and Baoshan blocks. Both north and south sections experienced the same structural evolution since D3 (a fault-propagation fold system occurred between 40 Ma and 28 Ma), D4 (steep right-lateral shear belt occurred between 28 Ma and 15 Ma), and D5 (normal faults after 15 Ma). The curvature first developed as a shovel-like top-to-the-NE thrust plane (S3) that formed under amphibolite-facies conditions between 40 Ma and 28 Ma. The following deformation events (D4 and D5) show orocline parallel foliation development under lower metamorphic conditions, indicating that the curvature of the Gaoligong orocline is not generated by additional rotation along multiple deformation events. However, due to the lack of orocline parallel foliation development for S3, and the lack of a proper position of the indenter, the Gaoligong orocline cannot be classified as a primary orocline nor a rotational orocline. The curved geometry is an interference pattern of topography relief to the shovel-like thrust plane that developed during D3. Our new reconstructed structural evolution concludes that the Gaoligong orocline is an “atypical” orocline.

Numerical simulation of deformations of a specimen of a composite helicopter blade as part of a resonant vibration set-up

To determine the fatigue life of the tail rotor blade of a helicopter made of polymer composite materials (CM), a method of fatigue testing of the specimens of the blade with accompanied numerical modeling of the deformed state has been developed. The tests are carried out on a resonant vibration set-up, with simultaneous reproduction of a forcing harmonic transverse force and a constant longitudinal tensile force. The tests are carried out by a vibration loading mode equivalent in fatigue damage, which includes one level of variable load in the thrust plane and in the plane of rotation. The equivalent mode is formed based on the variable loading spectrum of the blade, which is obtained from the results of flight measurements of the loads on the tail rotor, as well as the repeatability of the expected operating conditions of the helicopter. The tests are accompanied by computational and experimental studies, which include finite element calculation of the stress state and modal analysis of the standard blade and the test specimen, as well as the strain measuring of the structure. According to the results of the research, the vibration loading modes are corrected.

Raman spectroscopy in thrust-stacked carbonates: an investigation of spectral parameters with implications for temperature calculations in strained samples

Abstract. Raman spectroscopy is commonly used to estimate peak temperatures in rocks containing organic carbon. In geological settings such as fold–thrust belts, temperature constraints are particularly important as complex burial and exhumation histories cannot easily be modelled. Many authors have developed equations to determine peak temperatures from Raman spectral parameters, most recently to temperatures as low as 75 ∘C. However, recent work has shown that Raman spectra can be affected by strain as well as temperature. Fold–thrust systems are often highly deformed on multiple scales, with deformation characterised by faults and shear zones, and therefore temperatures derived from Raman spectra in these settings may be erroneous. In this study, we investigate how some of the most common Raman spectral parameters (peak width, Raman band separation) and ratios (intensity and area) change through a thrust-stacked carbonate sequence. By comparing samples from relatively low-strain localities to those on thrust planes and in shear zones, we show maximum differences of 0.16 for ID / IG and 0.11 for R2, while full width at half-maximum (FWHM[d]) and Raman band separation show no significant change between low- and high-strained samples. Plausible frictional heating temperatures of faulted samples suggest that the observed changes in Raman spectra are not the result of frictional heating. We also consider the implications of these results for how temperatures are determined using Raman spectra in strained and unstrained rock samples.

Integration of Vertical and Horizontal Deformation Derived by SAR Observation for Identifying Landslide Motion Patterns in a Basaltic Weathered Crust Region of Guizhou, China

In recent years, due to adverse geological conditions, intense human engineering activities, and extreme weather conditions, catastrophic landslides have frequently occurred in southwest China, causing severe loss of life and property. Identifying the kinematic features of potential landslides can effectively support landslide hazard prevention. This study proposes a remote sensing identification method for rotational, planar traction, and planar thrust slides based on geomorphic features as well as vertical and slope-oriented deformation rates. Rotational landslides are characterized by similar vertical and horizontal deformation rates, with vertical deformation mainly occurring at the head and gradually decreasing along the slope, while horizontal deformation mainly occurs at the foot and gradually increases along the slope. As for the planar slide, the dominant deformation is in the horizontal direction. It is further classified into the planar traction and planar thrust types according to the driving position. The vertical deformation of planar traction slides is concentrated at the foot, while the vertical deformation of planar thrust slides is concentrated at the head of the landslide. We identified 1 rotational landslide, 10 planar traction landslides and 10 planar thrust landslides in the basalt weathering crust area of Guizhou. Field investigations of three landslides verified the method’s accuracy. Combining two-dimensional rainfall and time-series deformations, we found that there is a significant positive correlation between landslide deformation acceleration and precipitation. The landslide kinematic identification method proposed in this paper overcomes the shortcomings of the inability to accurately characterize landslide motion by line-of-sight displacement and realizes the non-contact identification of active landslide motion patterns, which is an essential reference value for geological disaster prevention and control in the study area.

Interplay Between Crustal‐Scale Thrusting, High Metamorphic Heating Rates, and the Development of Inverted Thermal‐Metamorphic Gradients: Numerical Models and Examples From the Caledonides of Northern Scotland

AbstractUnderstanding the processes that produce high prograde metamorphic heating rates and the development of inverted metamorphic sequences in collisional thrust belts remains a fundamental challenge for tectonics and metamorphic petrology. New 2D finite element models of crustal‐scale thrusts with variable slip rates (10, 20, 35, 50 km Myr−1) are used to examine how thrust sheet emplacement contributes to these processes. In the models, average prograde heating rates of 31–118 °C Myr−1 are observed in the footwall, with maximum transient heating rates of ∼167 °C Myr−1 occurring at the highest slip rate. Also, thrust sheet emplacement produces an inverted thermal gradient in the model footwall. At slip rates of 10 km Myr−1, heating magnitudes &gt;200 °C are observed &gt;7 km structurally beneath the thrust plane. At slip rates of 20–50 km Myr−1, models produce thermal penetration depths of 4–5 km for similar heating magnitudes. Petrologically determined heating rates for thrust footwalls in the Scandian orogenic wedge of northern Scotland mostly yield rates consistent with model results (10–230 °C Myr−1). The model‐derived magnitude of inverted thermal gradients is also similar to those indicated in texturally determined deformation temperature transects across the Scandian orogenic wedge (100 °C–180 °C). Combined, these results indicate that high heating rates can be produced by fault slip at typical plate velocities. Additionally, this implies that crustal‐scale thrusts are likely to produce inverted metamorphic sequences in most systems, provided that P‐T conditions during slip allow for metamorphic or recrystallization processes that would preserve evidence for such features.

Pengukuran level pembentukan es (ICING) pada pemodelan menggunakan rancang bangun sensor berbasis perubahan frekuensi dengan induktor datar

Icing is one of the main dangers for the flight and are cumulative. The icing is a process of accumulation of ice on parts of the aircraft, which will lead to changes in geometry and resulted in a variety of other disorders. For example, there was a buildup of ice on the propellor (propeller) and the engine carburetor so it can reduce the thrust plane even caused the plane to fall freely (stall). For it needs to be designed and built the Icing Detector as well as the actuator in providing early warning of the existence of the calculation and the icing on the pilot.&#x0D; This instrument is designed with electronic units that use the oscillator as frequency generator and frequency meter based mikrokontroller ATmega8 as the measuring frequency. The surface of the sensor is made up of printed inductor with a broad surface for detection area. Sensors and electronic units connected by cable. In addition, modeling for the pilot indicators have been designed using the LCD.&#x0D; Research results suggest that testing on "Ice Accretion-Level Measurement On Modelling using printed Inductor Sensor Prototype Based On Frequency Shifting" has been a successful made in accordance with the expected functions. These instruments can detect the occurrence of icing and give an indication of the thickness of the ice. It is possible to form a flat sensor installation on the aircraft to be more unobtrusive air flow, as well as a spacious surface produces more accurate results.

Geomorphological Hazard in Active Tectonics Area: Study Cases from Sibillini Mountains Thrust System (Central Apennines)

In many areas of the Umbria-Marche Apennines, evident traces of huge landslides have been recognized; these probably occurred in the Upper Pleistocene and are conditioned by the tectonic-structural setting of the involved Meso-Cenozoic formations, in a sector of the Sibillini Mountains (central Italy). The present work aimed to focus on a geomorphological hazard in the tectonic-structural setting of a complex area that is the basis of several gravitational occurrences in different types and mechanisms, but nonetheless with very considerable extension and total destabilized volume. An aerophoto-geological analysis and geomorphological survey allowed verification of how the main predisposing factor of these phenomena is connected with the presence in depth of an important tectonic-structural element: the plane of the Sibillini Mountains thrust, which brings the pre-evaporitic member of the Laga Formation in contact with the Cretaceous-Eocene limestone lithotypes (from the Maiolica to the Scaglia Rosata Formations) of the Umbria-Marche sedimentary sequence. Another important element for the mass movements activation is the presence of an important and vast water table and related aquifer, confined prevalently by the different structural elements and in particular by the thrust plane, which has acted and has continued to act, weakening the rocky masses and the overlaying terrains.

Neoproterozoic geodynamics in NW India – evidence from Erinpura granites in the South Delhi Fold Belt

ABSTRACT Erinpura Granites form the basement for the Neoproterozoic Malani Igneous Suite in NW India. Based on this study, the Erinpura granites can be divided into Erinpura-East (gneissic fabric), a belt parallel to the southern sector of the South Delhi Fold Belt, and Erinpura-West (magmatic fabrics). EPMA dating on monazites gives a time frame of 890 to 860 Ma for crystallization of both types. The geochemically homogeneous peraluminous S-type granites with εNd values of −2.1 to −10.8 are interpreted as melting products of Archaean crust. REE pattern follows the pattern of the average continental crust, but Erinpura-East samples are more fractionated with steeper HREE depletion indicating melting in a deeper crustal level. A thermal pulse between 835 and 820 Ma constrains the timing of deformation in granite-gneisses during uplift along thrust planes, coeval with shear-bound exhumation of high-grade metamorphic rocks and initiated by delamination of the lower crust in this southern sector of the South Delhi Fold Belt. This is in contrast to the northern sector of the SDFB with arrested orogenic development and without considerable delamination or erosion of the lower crust. Latest movement related to the 200 Ma tectono-magmatic history overlaps with initiation of rifting during the Malani igneous event. A change from S-type to A-type granites and shift of isotopic signatures to εNd values of −2.8 to −1.7 indicate substantial contribution of asthenospheric material in the Malani melting process.