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The local heat transfer coefficient measurement with temperature oscillation induced by periodic thermal perturbation – usually via a Gaussian laser beam, was investigated for the impact of the spikiness (i.e., the standard deviation) elaborated in comparison with the analytical model for dimensional analysis. The statistically more robust technique that relies on the linearity of the spatial phase distribution of the test point array was favored when the target Biot number approaches unity in terms of its order of magnitude. The preferred upper limit for thermographic scanning was discussed as the simplification of later data processing is concerned. Nonetheless, the time elapsed for an acceptable periodic steady state, which in principle leans to the higher end of the target Biot number spectrum in a log scale, indicates the benefit from the time series of pointwise temperature measurement – as in the conventional single-blow testing, where the effect of spikiness, as well as that of the location of individual test point, holds. Note that the vicinity as the target Biot number approaches unity was again observed with higher preference.

The MICROSCOPE mission aims to test the weak equivalence principle (WEP) in orbit with an unprecedented precision of 10âˆ'15 on the Eötvös parameter thanks to electrostatic accelerometers on board a drag-free micro-satellite. The precision of the test is determined by statistical errors, due to the environment and instrument noises, and by systematic errors to which this paper is devoted. Systematic error sources can be divided into three categories: external perturbations, such as the residual atmospheric drag or the gravity gradient at the satellite altitude, perturbations linked to the satellite design, such as thermal or magnetic perturbations, and perturbations from the instrument internal sources. Each systematic error is evaluated or bounded in order to set a reliable upper bound on the WEP parameter estimation uncertainty. [ABSTRACT FROM AUTHOR]

Biochemical mechanisms are temperature dependent. Brain temperature shows wide variations across brain states, and such changes may explain quantitative changes in network oscillations. Here, we report on the relationship between various hippocampal sharp wave ripple features to brain temperature. Ripple frequency, occurrence rate, and duration correlated with temperature dynamics. By focal manipulation of the brain temperature in the hippocampal CA1 region, we show that ripple frequency can be increased and decreased by local heating and cooling, respectively. Changes of other parameters, such as the rate of sharp wave-ripple complex (SPW-R) and ripple duration were not consistently affected. Our findings suggest that brain temperature in the CA1 region plays a leading role in affecting ripple frequency, whereas other parameters of SPW-Rs may be determined by mechanisms upstream from the CA1 region. These findings illustrate that physiological variations of brain temperature exert important effects on hippocampal circuit operations. [ABSTRACT FROM AUTHOR]

• Initial polymer structure; influenced by photo-polymerisation variables, impacts the thermal response of resin matrices. • Systems polymerised rapidly are more influenced by thermal perturbation. • Accelerating polymerisation confers reduced chain extension below the glass transition temperature. • Slower polymerised systems display greater relative order before and after the glass transition point. The structure of the polymer phase of dental resin-based-composites is highly sensitive to photo-polymerisation variables. The objective of this study was to understand how different polymer structures, generated with different photo-polymerisation protocols, respond to thermal perturbation. Experimental resins were prepared from a series of Bis-GMA/TEGDMA blends (40/60, 50/50 and 60/40 wt.%), with either Camphorquinone/DMAEMA or Lucirin TPO as the photo-initiator system. Resins were photo-polymerised, in a disc geometry, at either relatively 'high' (3000 mW cm−2 for 6 s) or 'low' (300 mW cm−2 for 60 s) irradiances ensuring matched radiant exposures (18 J cm−2). Specimens were heated, from 20−160 °C at a rate of 5 °C min−1, whilst simultaneous synchrotron X-ray scattering measurements were taken at 5 °C increments to determine changes in polymer chain segment extension and medium-range order as a function of temperature. For each unique resin composition (n = 3), differential scanning calorimetry was used to measure glass transition temperatures using the same heating protocol. A paired t-test was used to determine significant differences in the glass transition temperature between irradiance protocols and photo-initiator chemistry at ɑ = 0.05. Resins pre-polymerised through the use of TPO and or high irradiances demonstrated a reduced rate of chain extension indicative of lower thermal expansion and a larger decrease in relative order when heated below the glass transition temperature. Above the transition temperature, differences in the rate of chain extension were negligible, but slower converted systems showed greater relative order. There was no significant difference in the glass transition temperature between different photo-initiator systems or irradiance protocols. The evolution of chain extension and medium-range order during heating is dependent on the initial polymer structure which is influenced by photo-polymerisation variables. Less ordered systems, generated at faster rates of reactive group conversion displayed reduced chain extension below the glass transition temperature and maintained lower order throughout heating. [ABSTRACT FROM AUTHOR]

Abstract The thermal shimming technology is initially used to adjust the temperature field around the capsule in order to obtain an isothermal distribution and meet the requirement of a high-quality uniform deuterium-tritium (DT) ice layer. In this paper, we focus on the asymmetric heating scheme on upper and lower heaters, which are used both in the quasi-steady layering process and the rapid-cooling process. A dynamic modulation scheme with asymmetric heating is first proposed to attenuate the cooling-induced thermal perturbation around the capsule. Thermal and hydrodynamic simulations of the cryogenic target are numerically conducted. An axisymmetric model based on the NIF-scale indirect-drive target is built and used in simulations. A variety of dynamic modulation schemes are studied and compared with each other. In the layering process, the asymmetric heating scheme is validated to be effective in reducing the low-mode roughness of the DT ice layer. In the rapid cooling, the thermal uniformity around the capsule can be greatly improved by using the dynamic heating modulation scheme when the DT layer is frozen to 1.5 K below its triple point temperature. At a constant cooling rate of 0.4 K/s, the temperature difference on the capsule outer surface reaches ∼24.5 mK without dynamic heating. By employing a nonlinear modulation with symmetric heating, this value can be decreased by 25%. Based on these results, further improvement can be achieved by optimizing the modulation with asymmetric heating and the temperature difference can be significantly reduced to ∼6.0 mK, which is a factor of four lower than the original value. Highlights • Applying asymmetric heating can minimize low-mode roughness of DT inner surface. • Dynamic heating modulation during the rapid cooling is proposed and investigated. • The heat flux should be adjusted dynamically to accommodate thermal perturbation. • Nonlinear heating modulation can be optimized by using asymmetric heating scheme. • Thermal uniformity can be greatly improved with the optimal heating modulation. [ABSTRACT FROM AUTHOR]

Considering that in many practical problems thermal expansion and thermal perturbations are the factors that granular materials are often faced with, in this study the 3D numerical experiments based on the discrete element method (DEM) were first carried out to investigate their effects in a binary granular mixture at high temperature levels. The granular system consists of mixed ceramic and steel grains. The thermal expansion dynamics induced is analyzed in detail. Besides, the stress in pebbles (or force chains) inside the system was founded to be much relieved by temperature changes and force networks were subsequently degenerated in magnitude and space, especially under larger temperature change amplitudes. At the same time, the segregation between the statistical probability distributions of internal forces of the two grain components was also observed, reflecting that thermal perturbations have induced the density segregation between the two kinds of solid materials and damaged their mixing homogeneity in space. Moreover, the effect of friction was also studied. It was observed that friction can play the inhibiting role on the effects of both thermal expansion and thermal perturbations, but it would become insignificant once the friction coefficient exceeds one specific threshold value. These messages may provide important implications for the handling of granular materials. [ABSTRACT FROM AUTHOR]

• A review of ages of granite emplacement is reported • Low temperature thermochronology as a new tool for geothermal exploration • Apatite fission track data may reveal buried magmatic intrusions • The Mid-Tuscany Metamorphic Ridge is a promising exploration target High enthalpy geothermal fields are typically associated with magmatic intrusions providing the heat source that makes the system working. To identify and locate these features, geothermal exploration generally uses expensive, time-consuming approaches that could also require complex logistics. Here we present the result of a pilot study carried out in the well-known Larderello-Travale geothermal field (Tuscany, Italy), exploring the possibility of an advantageous use of low temperature thermochronology to obtain useful information implementing the geothermal exploration workflow. The majority of the collected samples (except one retaining the apatite fission-track age of undisturbed, or almost undisturbed country rocks) cluster in a close time span ranging between 3.1±0.8 and 1.9±1.1 Ma, which clearly matches the known ages of magmatic bodies in the region. We propose that this approach can contribute to the identification of sectors recently affected by thermal perturbations that could have led to the development of hydrothermal systems. This approach has allowed us to achieve clues for the presence of subsurface magmatic intrusions even in areas where currently there are no direct indications. Given the small number and distribution of analyzed samples, our contribution represents a first attempt that demonstrates the potentiality of the method in geothermal exploration, but that needs to be verified by further studies involving a larger sampling density. Overall, our results suggest how low temperature thermochronology can be a powerful, fast, and cost-effective tool for geothermal exploration, to be used jointly with the classical methods. [ABSTRACT FROM AUTHOR]

In this article, the thermodynamic characteristics and bifurcation of MWCNTs impacted by hydrogen atoms were studied. The impact between MWCNTs and hydrogen atoms was regarded as white noise. Nonlinear differential items were introduced to explain the hysteretic phenomena of MWCNTs stiffness, and a nonlinear dynamic model of MWCNTs impacted by hydrogen atoms was developed where the nonlocal effect is considered. The conditions of stochastic Hopf bifurcation were identified, and the fractal boundary of the safe basin was provided. The reliability function of the system was solved, and the probability density of the first-passage time was determined. Theoretical analysis and numerical simulation show that stochastic Hopf bifurcation occurs in the variation of parameters; the boundary of safe basin has fractal characteristics, the area of safe basin decreases when the intensity of the noise increases; the hysteretic nonlinearity of MWCNTs stiffness can affect the system's stability and safe basin, which decides the actual hydrogen storage capacity of MWCNTs. [ABSTRACT FROM AUTHOR]

The Eastern and Southeastern Asian regions witness the strongest land-ocean and lithosphere-asthenosphere interactions. The extreme diversity of geological features warrants a unified study for a better understanding of their geodynamic uniqueness and/or ubiquity from a regional perspective. In this paper we have explored a large coverage of potential field data and have detected high resolution Moho and Curie depths in the aforementioned regions. The oldest continental and oceanic domains, i.e. the North China craton and the Pacific and Indian Ocean have been found thermally perturbed by events probably linked to small-scale convection or serpentinization in the mantle and to numerous volcanic seamounts and ridges. The thermal perturbation has also been observed in proximity of the fossil ridge of the western Philippine Sea Basin, which shows anomalously small Curie depths. The western Pacific marginal seas have the lowest Moho temperature, with Curie depths generally larger than Moho depths. The contrary is true in most parts of easternmost Eurasian continent. Magmatic processes feeding the Permian Emeishan large igneous province could have also been genetically linked to deep mantle/crustal processes beneath the Sichuan Basin. The regionally elongated magnetic features and small Curie depths along the Triassic Yangtze-Indochina plate boundary suggest that the igneous province could be caused by tectonic processes along plate margins, rather than by a deep mantle plume. At the same time, we interpret the Caroline Ridge, the boundary between the Pacific and the Caroline Sea, as a structure having a continental origin, rather than as hotspot or arc volcanism. The surface heat flow is primarily modulated by a deep isotherm through thermal conduction. This concordance is emphasized along many subduction trenches, where zones of large Curie depths often correspond with low heat flow. Local or regional surface heat flow variations cannot be faithfully used in inferring deep thermal structures, which can be better constrained overall through Curie depths detected from surface magnetic anomalies. [ABSTRACT FROM AUTHOR]

In this article, stochastic nonlinear dynamic characteristics and safe basin of a Li-doped graphene impacted by hydrogen atoms are studied. The interaction of hydrogen atoms to a graphene is regarded as Gauss white noise excitation. The nonlinear dynamic model of a Li-doped graphene impacted by hydrogen atoms is developed, in which the effect of Li atoms on graphene's stiffness is considered. The local and global stability of the system are analyzed, and the system's safe basin is obtained. The reliability function of the system is solved, and the probability of the first-passage time is determined. Theoretical analysis and numerical simulation show that the safe basin's boundary has fractal characteristics, which means chaos induced by noise; the safe basin's area decreases when the noise's intensity increases; the inhomogeneity of the graphene's stiffness can affect the system's safe basin, which decides the graphene's actual hydrogen storage capacity. Finally, the phenomena of the graphene's stiffness changing with the temperature are explained. [ABSTRACT FROM AUTHOR]

Using a random thermal perturbation (RTP) model this study investigates the process of magmatic segmentation along mid-oceanic ridge (MOR) axes as a function of the upwelling dynamics, controlled by coupled solidification–melting processes. The RTP model suggests that the variation in along-axis velocity ( V L ) fields constitutes the underlying mechanism of segmentation in natural MORs, showing temperature variations within a steady-state range, irrespective of large initial thermal perturbations imposed at the model base. The V L patterns are initially transient, characterized by multi-order segments, but attain a stable configuration with dominantly large segments (average size ~ 100 km) within a time scale of 2.3 Ma. Buoyant-melt driven thermal convection explains this transient segmentation. Small scale convection cells are found to be progressively consumed by larger cells, resulting in a stable convection structure over a similar time scale. Slow- and fast-spreading ridges (SSR and FSR) undergo upwelling with contrasting melt flow patterns. SSRs involve melt feeding into the ridge axis by horizontal flows from segment centers, trailing into large-scale conduits at an early stage. With time, vertical upwelling occurs throughout the segment. In the case of FSRs, both melt supply avenues prevail throughout their development. We also evaluate the variation of the across-axis flow velocity ( V T ) to investigate the mode of geometric evolution of MORs. Time series V T maps suggest that a ridge structure develops through localization of discrete axes ( V T = 0) with offsets varying up to 15 km, which coalesce with one another to form a single axis. The matured ridge, however, retains higher-order offsets (up to 9 km). [ABSTRACT FROM AUTHOR]

A three-dimensional numerical study is performed to explore the effect of pulsed spanwise-periodic surface thermal perturbation (also denoted as thermal bump) in a Mach 1.5 flat plate laminar boundary layer. A high-resolution upwind-biased Roe method is used with the compressive Van Leer harmonic limiter on a suitably refined mesh. The dependence of flow stability characteristics on the variation of thermal bump geometry (shape and dimension) and pulsing properties (disturbance amplitude and frequency) is assessed. It is shown that the finite-span thermal bumps generate streamwise vortices. When the thermal bump is pulsed, vortex shedding is observed, and the streamwise vorticity grows with the downstream distance. Analysis of the integrated disturbance energy indicates that the streamwise kinetic disturbance energy dominates over those associated with other two velocity and thermodynamic components. Immediately downstream of the bump, the dominant frequency corresponds to that of the imposed excitation while higher harmonic components are observed farther downstream. An analysis of parametric variation of bump shape and dimension indicates that finite bump span is important in injecting three dimensionality and that the rectangular shape results in faster disturbance growth than the circular one. The study also concludes that disturbance growth is non-linear with bump temperature and has a strong connection with pulsing frequency. [ABSTRACT FROM AUTHOR]

The effects of structure nonuniformity and thermal perturbation on properties of proton conductivity in hydrogen-bonded systems with damping exposed in an externally applied electric-field have been numerically studied by fourth order Runge-Kutta method in our soliton model. The results obtained show that the proton-soliton is very robust against the structure disorder including the fluctuation of the force constant and disorder in the sequence of masses and thermal perturbation and damping effect of medium, its velocity of conductivity increases with increasing externally applied electric-field and with decreasing damping coefficient of medium, but the proton-soliton disperses at quite great fluctuations of force constant and damping coefficient. In the meantime, the proton-soliton in ice crystals is thermally stable in the region of temperature of T ≤ 273 K. From the numerical simulation, we find out that the mobility (or velocity) of proton conduction in ice is a nonmonotonic function of temperature in the temperature region of 170-273 K, i.e., it increases initially, reaches a maximum at about 191.4 K, subsequently decreases to a minimum at about 211.6 K, and then increases again. This changed rule of mobility obtained consists qualitatively with its experimental datum in ice in the same temperature region. Thus these results provide an evidence for the soliton excited in the hydrogen-bonded systems. [ABSTRACT FROM AUTHOR]

Summary: A new temperature-profile method was recently developed for analyzing perturbed flow conditions in strongly heated porous media. The method uses high-resolution temperature data to estimate the magnitude of the heat-driven liquid and gas fluxes that form as a result of boiling, condensation, and recirculation of pore water. In this paper, we evaluate the applicability of this new method to the more complex flow behavior in fractured formations with porous rock matrix. In such formations, the porous but low-permeable matrix provides most of the mass and heat storage capacity, and dominates conductive heat transfer. Fractures, on the other hand, offer highly effective conduits for gas and liquid flow, thereby generating significant advective heat transfer. After establishing the accuracy of the temperature-profile method for fractured porous formations, we apply the method to analyze the perturbed flow conditions in a large-scale underground heater test conducted in unsaturated fractured porous tuff. The flux estimates for this test indicate a significant reflux of water near the heat source, on the order of a few hundred millimeter per year – much larger than the ambient percolation flux of only a few millimeter per year. [Copyright &y& Elsevier]

Numerical simulation shows that the hot plumes can be formed by the self-accelerated process if local thermal perturbation is present. Since the local thermal perturbation may exist extensively near the CMB and the transition zone around 670 km, the number of the hot plumes should be great. The cold plume seems to be originated by the subduction slabs. Because the subduction belts distribute extensively on the Earth’s surface, the number of the cold plume should be also great. However, the observed number of the superplumes is much less than the supposed ones. A simple 2D model of whole mantle convection is designed to investigate the interaction between plumes and thermal anomalies. The hot thermal anomalies (HTA) are imposed at CMB and a depth of about 670 km discontinuity, corresponding to two plausible locations of the hot plumes origination. And, the cold thermal anomalies (CTA) are imposed near the surface and 670 km discontinuity, corresponding to the subducted slabs and possible accumulation of slabs at 670 km discontinuity. The numerical results show that the fixed HTA does not originate a new plume. It draws the hot plume to move towards itself and stabilizes the plume at its own position. The imposed free HTA moves towards the hot plume, and finally merge with the plume. The situation for the CTA is similar to that for the hot one. From the numerical results, we can reach the following conclusions. It is very difficult for the HTA/CTA to originate a new hot/cold plume in a convective flow field. The boundary instability is suppressed by the developed plumes. Instead of originating new hot/cold plumes, the HTA/CTA interact with the plumes to form huge superplumes. This might be one reason for the question, why the number of the superplumes is so limited. [ABSTRACT FROM AUTHOR]

Central and Southern Africa is home to major Archean Cratons, flanked by Proterozoic mobile belts. The region is characterized by anomalously high topography and shallow Curie depth (Z b). Factors controlling topography and Z b anomalies in old continental crusts remain poorly understood. In this study, we present high-resolution Moho undulation (Z m) derived with gravity spectral technique. Archean Cratons and Proterozoic belts are mostly characterized by deep Moho (>36 km), whereas the Moho depths in Mozambique belts is mostly shallow (~26 to 41 km). Extremely shallow Z b (<10 km) is dominant in Archean Cratons, whereas intermediate Z b (10–25 km) is prevalent in the mobile belts. The Curie points are mostly above the Moho. Low surface heat flow (Q s) in Archean Cratons indicate that Z b is not correlated with thermal perturbation. Shallow Z b are mostly found in areas with low V p /V s ratio, predominantly felsic lower crust and sharp Moho. Shallow Z b also correlate with intense metasomatism and mineral enrichment, as well as depletion in basaltic components and geochemical overprinting by multiple episodes of melt and fluid infiltration. Crustal composition is the main factor that controls shallow Z b in Central and Southern Africa Archean Cratons. The regional elevated topography is not due to thermal perturbation as mostly argued by mantle plume hypothesis, but may be caused by regional thermo-chemical mantle upwelling dominated by composition. • Shallow Z b (<10 km) in Southern Africa Archean Cratons is mostly controlled by crustal composition. • Regional topography uplift is not strongly correlated with thermal perturbation of mantle plume. • Southern Africa thermo-chemical upwelling was partially caused by composition. [ABSTRACT FROM AUTHOR]

A 150–200 km thick, cold (35–45 mWm−2), melt-depleted lithospheric keel characterised the eastern cratons of the Indian shield at the end of the Precambrian. Differing chemical- and isotopic-characteristics, and ages of the crust and mantle rocks reveal the decoupling of the crust and mantle beneath the cratons, beginning at 2.45 Ga, in the Bastar craton. The Pan-African event was more pervasive and brought about widespread reworking in most of the cratons of the shield. Major-, trace- and rare-earth elements combined with Sr, Nd and Hf isotope data suggest a heterogenous SCLM beneath southern India. The trace element signatures of xenoliths and the presence of majoritic garnet inclusions in diamond suggest that some kimberlites were derived from the mantle transition zone. Mesoproterozoic (1.2–1.4 Ga) modal and cryptic refertilisation by asthenosphere-derived, low-degree carbonated melts led to the generation of the fluids responsible for the metasomatic transformation of the source rocks. The western craton of the shield has witnessed more severe reactivation than the eastern due to the frequent interaction of the Indian plate with mantle plumes. One plume caused major igneous activity during the late Cretaceous, synchronous with crustal attenuation, rifting and the ridge-jump at 66 Ma, in the Indian Ocean. By the end of the Palaeocene the geotherm of the western craton had risen from 50 to 55 mWm−2 in the Proterozoic to a peak 80–90 mWm−2. This increase in heat flow not only modulated the mantle thermal regime, but led to a net loss of more than 100 km of lithosphere and to destabilisation of the craton. After this thermal event, the lithosphere preserves a thickness of barely 60–80 km, and a thin crust (10–21 km) beneath the continental margin in the west. These changes decratonized the western part of the shield and the transitional region further west in the Indian Ocean where the continental ridges are almost devoid of crustal sections and the lithosphere is ~60 km thick. The waning of the Deccan Traps (65 Ma) magmatism was marked by alkaline intrusive activity along the western margin of the shield, probably derived from the SCLM in response to the rise of the mantle plume. Low degree (2–3%) partial melting of a modally and cryptically metasomatized source may have been involved in the generation of alkaline magmas from a depleted mantle source variously contaminated by an enriched endmember. • Polygenetic xenolith suite indicates crust-mantle decoupling beneath India. • Modal and cryptic metasomatism leads to replacement of SCLM by fertile mantle. • Three superimposed thermomagmatic episodes since Proterozoic. • Lithosphere-asthenosphere interaction resulted in attrition of SCLM and decratonization. [ABSTRACT FROM AUTHOR]

Abnormal pore pressures in excess of the hydrostatic equilibrium are observed in natural and artificial sediment systems worldwide. Such overpressure exerts a fundamental control over the diagenesis, stability, and productivity of both sedimentary reservoirs. The basin dynamics for overpressure generation involve complex THMC processes during sediment accumulation. In this paper, we develop a generic framework for thermo-chemical consolidation in natural and artificial sedimentary sequences by extending Biot's classical poroelasticity. The proposed theoretical model is then conveniently recast into an explicit form for one-dimensional sedimentation. The resulting formulation essentially extends the original Gibson's theory by incorporating coupled THMC effects in general sedimentary sequences, and a hierarchical scrutiny of different overpressuring mechanisms thus becomes straightforward. Moreover, a closed-form equation is derived from the new chemo-thermo-poroelasticity model for accreting sediments, and the critical temperature for pore pressure changes via hydration/dehydration is thus determined. The model demonstrates that overpressuring and depressuring are not mutually exclusive because of the competition between water volume changes and thermal strains induced by chemical reactions. By using evolutive properties of a reactive artificial sediment, our model calculations have highlighted the critical influences of the sediment and environment temperatures and deposition rate on the contribution of each overpressuring mechanism. [ABSTRACT FROM AUTHOR]

Molecular detail of the trehalose crystallization process was obtained during thermal perturbation through real-time monitoring using a Quantum Cascade Laser (QCL) microscope and 2D correlation spectroscopy. We were able to separate QCL IR spectral data based on the hyperspectral images acquired into key segments that defined the crystallization events: (1) trehalose in solution or the pre-transition phase, (2) nucleation and crystallization transition and (3) the crystal growth phase. Furthermore, the hyperspectral images allowed for the determination of the region of interest (ROI) allowing for the selection of QCL IR spectral data directly associated with the crystallization process. This approach allowed for the distinction of different types of intermolecular Hydrogen bonding interactions and dynamics involving α,α-trehalose with its aqueous environment, the dihydrate and between trehalose molecules. To our knowledge this is the first time that a real-time description of the molecular events that lead to trehalose crystallization have been described. Image 1 • A quantum cascade laser microscope was used for the real-time monitoring of trehalose crystallization. • 65% (w/v) trehalose was subject to thermal stress causing the crystallization phenomena to occur. • 2D IR synchronous plot was sensitive to the different stages of the crystallization process. • Correlations between key vibrational modes within trehalose with itself and H 2 O were made. [ABSTRACT FROM AUTHOR]

A pseudobrookite, approximately Mg 0.04 Fe2+ 0.85 Ca 0.01 Al 0.05 Fe3+ 0.16 Ti 1.89 O 5 , was discovered in Fe-Ti oxide intergrowths in a spinel–garnet-bearing granulite from the Xuwujia Paleoproterozoic ultrahigh-temperature (UHT) metamorphic region within the Khondalite Belt of the North China Craton. The presence of this pseudobrookite indicates a peak temperature possibly over 1120 °C, when compared with experimental data. Ferric pseudobrookite grains (Fe3+ up to 0.58 per formula unit) from the same granulite outcrop record retrograde temperatures as low as 940 °C. Titanomagnetite and ilmenite intergrowths that resulted from reduction-exsolution, which was buffered by the decomposition of high-Ti pseudobrookite grains, recorded a post peak temperature up to 1050 °C. The thermal gradient (>100 °C/kbar) required to generate the UHT metamorphic bodies in an area over 10,000 km2 around the Jining area was modeled by the finite element method. The thermal modeling results show that, (1) lithospheric thermal erosion induced by a mantle plume with potential temperature of >1550 °C could not have provided enough thermal perturbation to allow the observed UHT metamorphism; (2) underplating at the scale of even the largest known horizontal magma intrusion on Earth would not be able to elevate the geotherm to the gradients required for the observed UHT metamorphism; and (3) intraplating of dykes and intrusions at the depth of this UHT metamorphism was able to increase the local temperature field to the required gradients. These modeling results suggest that a modern back-arc may not be able to provide sufficient heat at the middle crust level for UHT metamorphism. The UHT metamorphism in the study area was probably accompanied by an orogeny–plume interaction event, which simultaneously supplied heat through thermal erosion, magma underplating and magma intraplating. • Fe-Ti oxides record a metamorphic temperature of >1050 °C in the Khondalite Belt from the North China Craton. • Back-arc shortening cannot explain the thermal gradient (>100 °C/kbar) corresponding to the regional UHT metamorphism. • It required a thermal perturbation related to orogeny–plume interaction. [ABSTRACT FROM AUTHOR]