Thermal Peak Research Articles

Thermal decomposition and combustion behavior of potassium perchlorate catalyzed by LaFeO3

To improve the combustion behavior of potassium perchlorate-based pyrotechnics, this study successfully prepared perovskite LaFeO3 with nitrates as raw materials using the co-precipitation method and characterized perovskite LaFeO3 through X-ray diffraction (XRD), scanning electron microscopy (SEM), and energy dispersive spectrometry (EDS). Moreover, it investigated the catalytic effect of LaFeO3 on the thermal decomposition of potassium perchlorate (KP) through the differential scanning calorimetry (DSC) and thermogravimetric analysis (TG) and explored the thermal reaction behavior of pyrotechnics composed of KP and lactose. The results show that the thermal decomposition temperature of KP was 552 ​°C by adding LaFeO3, reduced by 58 ​°C. The temperature of catalytic decomposition was exactly the extrapolated onset temperature of the endothermic melting peak of KP. The addition of LaFeO3 caused the premature decomposition of the KP not yet molten, thus generating more heat in its thermal decomposition. Moreover, the addition of LaFeO3 reduced the thermal reaction peak temperature of pyrotechnics by 7 ​°C and increased the burning rate to more than two times.

The phonon thermal Hall angle in black phosphorus

The origin of phonon thermal Hall Effect (THE) observed in a variety of insulators is yet to be identified. Here, we report on the observation of a thermal Hall conductivity in a non-magnetic elemental insulator, with an amplitude exceeding what has been previously observed. In black phosphorus (BP), the longitudinal (κii), and the transverse, κij, thermal conductivities peak at the same temperature and at this peak temperature, the κij/κjj/B is ≈ 10−4−10−3 T−1. Both these features are shared by other insulators displaying THE, despite an absolute amplitude spreading over three orders of magnitude. The absence of correlation between the thermal Hall angle and the phonon mean-free-path imposes a severe constraint for theoretical scenarios of THE. We show that in BP a longitudinal and a transverse acoustic phonon mode anti-cross, facilitating wave-like transport across modes. The anisotropic charge distribution surrounding atomic bonds can pave the way for coupling between phonons and the magnetic field.

Biochar as smart organic catalyst to regulate bacterial dynamics during food waste composting

The impact of wheat straw biochar (WSB) on bacterial dynamics succession during food waste (FW) composting was analyzed. Six treatments [0(T1), 2.5(T2), 5 (T3), 7.5 (T4), 10 (T5), and 15 %(T6)] dry weight WSB were used with FW and saw dust for composting. At the highest thermal peak at 59 ℃ in T6, the pH varied from 4.5 to 7.3, and electrical conductivity among the treatments varied from 1.2 to 2.0 mScm1. Firmicutes (25–97 %), Proteobacteria (8–45 %), and Bacteroidota (5–50 %) were among the dominate phyla of the treatments. Whereas, Bacillus (5–85 %), Limoslactobacillus (2–40 %), and Sphingobacterium (2–32 %) were highest among the identified genus in treatments but surprisingly Bacteroides was in greater abundance in the control treatments. Moreover, heatmap constructed with 35 various genera in all the treatments showed that Gammaproteobacterial genera contributed in large proportion after 42 days in T6. Additionally, a dynamic shift from Lactobacillus fermentum to higher abundance of Bacillus thermoamylovorans was reported on 42 days of FW composting. Biochar 15 % amendment can improve FW composting by influencing bacterial dynamics.

Durability characteristics of recycled high performance concretes under an aggressive environment (sea water)

With the increase of solid construction waste (CSW) due to the acceleration of urbanization in Algeria, many ecological and environmental issues have been raised. Recycling and reuse of construction waste helps to reduce pollution, carbon emissions and preserve resources. Few studies have focused on the durability characteristics of concretes based on fine aggregates recycled from brick and concrete waste. The main purpose of this study is to formulate and analyze the performance of HPC based on waste brick and concrete fines. The substitution of alluvial sand with brick fines, causes the reduction of the heat of hydration and delays the appearance of the thermal flux peaks. while HPC rich in crushed concrete waste increases the heat of hydration. The appearance of heat flux peaks coincides for all mixtures with fines of waste concrete substitution and they will be delayed and prolonged for HPC with sand based on waste brick.

Unexpected biotic homogenization masks the effect of a pollution gradient on local variability of community structure in a marine urban environment

Urbanization of coastal habitats, often exemplified by harbors and marinas, has led to various ecological paradigms, questioning the functioning of these new ecosystems. In the present study we investigated, in a large Mediterranean harbor, whether spatial variation of pollution is present and if this variability drives the structure of the sessile community. We hypothesized locations to have significantly different communities, based on the assumption on the occurrence of environmental gradients of pollution that would constitute selective filters. Three distinct community types were identified in June, coinciding with spatially variable contaminants in sediments. We observed then an unexpected shift of the community between June and August associated to a sharp decrease in biodiversity and a decline of most species, masking the effects of local variation and thus leading to the homogenization of the biodiversity within the harbor. This shift coincided with successive heatwaves (the longest lasting 13 days over 25 °C, with a thermal peak at 28 °C) which might potentially be associated with a die-off in the harbor communities, regardless of location.

Energy Conversion and Transfer in the Luminescence of CeSc3(BO3)4:Cr3+ Phosphor.

Novel near-infrared (NIR) phosphors are in demand for light-emitting diode (LED) devices to extend their suitability for new applications and, in turn, support the sustainable and healthy development of the LED industry. The Cr3+ has been used as an activator in the development of new NIR phosphors. However, one main obstacle for the Cr3+-activated phosphors is the low luminescence efficiency due to the spin-forbidden d-d transition of Cr3+. The rare-earth (RE) huntite minerals that crystallize in the form of REM3(BO3)4 (M = Al, Sc, Cr, Fe, Ga) have a large family of members, including the rare-earth scandium borates of RESc3(BO3)4. Interestingly, in our research, we found that the luminescence efficiency of Cr3+ in the CeSc3(BO3)4 host, whose quantum yield was measured at 56%, is several times higher than that in GdSc3(BO3)4, TbSc3(BO3)4, and LuSc3(BO3)4 hosts. Hereby, the energy conversion and transfer in the luminescence of CeSc3(BO3)4:Cr3+ phosphor were examined. The Stokes shift of electron energy conversion within the Cr3+ 4T2g level for the emission at 818 nm and excitation at 625 nm in CeSc3(BO3)4 host was evaluated to be 3775.1 cm-1, and the super-large splitting energy of the 2F5/2 and 2F72 sub-states of the Ce3+ 4f1 state, about 3000 cm-1, was found in CeSc3(BO3)4 host. The typical electronic thermal vibration peaks were observed in the excitation spectra of CeSc3(BO3)4:Cr3+. On this basis, the smallest phonon energy, around 347.7 cm-1, of the CeSc3(BO3)4 host was estimated. Finally, the energy transfer that is responsible for the far higher photoluminescence of Cr3+ in CeSc3(BO3)4 than in other hosts was proven through the way of Ce3+ emission and Cr3+ reabsorption.

RDX crystals with high sphericity prepared by resonance acoustic mixing assisted solvent etching technology

In order to obtain high-quality spherical RDX crystal particles, the RDX crystals were suspended in a mixed solvent of cyclohexanone and cyclohexane, subsequently a solvent etching study was carried out under the action of vibration/acoustic flow coupled flow field, which generated by resonance acoustic mixing. The effects of solvent ratio, temperature, acceleration and experiment time on morphology as well as particle size of RDX crystals were studied. Not only were the morphology, particle size distribution and crystal form of RDX crystals determined, but also the thermal decomposition performance and mechanical sensitivity of spherical RDX were examined and discussed. Results indicated that under the process of solvent/non-solvent volume ratio at 1:2, temperature of 40°C, acceleration of 40 g and experiment time of 4 h, α-type RDX crystal with sphericity of 0.92 can be obtained. Furthermore, the median particle size (D50) of spherical RDX crystals is 215.8 μm with a unimodal particle size distribution (size span 1.34). For one thing, the thermal decomposition peak temperature of spherical RDX is about 2.5°C higher than that of raw RDX, and apparent activation energy reaches 444.68 kJ/mol. For another thing, impact sensitivity and friction sensitivity of spherical RDX are 18.18% and 33.33% lower than that of raw RDX, respectively. It demonstrates that safety of spherical RDX under thermal, impact and friction stimuli has been improved.

Preparation and Properties of RDX@FOX-7 Composites by Microfluidic Technology

1,3,5-trinitro-1,3,5-triazacyclohexane (RDX) is a type of high energy explosive, its application in weapon systems is limited by its high mechanical sensitivity. At the same time, 1,1-diamino-2,2-dinitroethylene (FOX-7) is a famous insensitive explosive. The preparation of RDX@FOX-7 composites can meet the requirements, high energy and low sensitivity, of the weapon systems. It is difficult for the reactor to achieve uniform quality of composite material, which affects its application performance. Based on the principle of solvent-anti-solvent, the recrystallization process was precisely controlled by microfluidic technology. The RDX@FOX-7 composites with different mass ratios were prepared. At the mass ratio of 10%, the RDX@FOX-7 composites are ellipsoid of about 15 μm with uniform distribution and quality. The advantages of microscale fabrication of composite materials were verified. The results of structure characterization showed that there is no new bond formation in RDX@FOX-7, but the distribution of two components on the surface of the composite was uniform. Based on the structure characterization, we established the structure model of RDX@RDX-7 and speculated the formation process of the composites in microscale. With the increase of FOX-7 mass ratios, the melting temperature of RDX was advanced, the thermal decomposition peak of RDX changed to double peaks, and the activation energy of RDX@FOX-7 composite decreased. These changes were more pronounced between 3 and 10% but not between 10 and 30%. The ignition delay time of RDX@FOX-7 was shorter than that of RDX and FOX-7. RDX@FOX-7 burned more completely than RDX indicating that FOX-7 can assist heat transfer and improve the combustion efficiency of RDX.

Variation on propagation of Rayleigh waves in thermo-poroelastic solids

We analyse the dispersion and attenuation of Rayleigh-wave propagation along on isothermal free surface of a thermo-poroelastic medium. The thermo-poroelastic theory, including the Lord-Shulman (LS) and Green-Lindsay (GL) theories, predicts three compressional waves and one shear wave, which induce two Rayleigh-type surface waves, R1 and R2 modes along the interface by evanescent potential functions specified by vertical imaginary wavenumbers. The GL model can give a stronger P1 and P2 wave thermal attenuation and consequently a stronger velocity dispersion than the LS model. We investigate the influence of frequency and surface boundary condition. The additional thermal diffusion exhibits the inverse dispersion in R1 waves, and makes the pseudo surface-wave transition under the closed (CP) and partial permeable (PP) surface toward high frequencies. Another T wave affects the energy inference along the surface and induce the other R2 waves under the open surface (OP). The thermal dispersion occurs at characteristic frequencies around the thermal relaxation peaks, which induces the high-velocity T wave toward low frequencies when the Maxwell–Vernotte–Cattaneo relaxation time increases. Until the T wave propagates faster than the P2 wave, the Rayleigh equations lose the R2 poles making the prohibition of R2-wave propagation.

Does aerobic scope influence geographical distribution of teleost fishes?

Many abiotic and biotic factors are known to shape species' distributions, but we lack understanding of how innate physiological traits, such as aerobic scope (AS), may influence the latitudinal range of species. Based on theoretical assumptions, a positive link between AS and distribution range has been proposed, but there has been no broad comparative study across species to test this hypothesis. We collected metabolic rate data from the literature and performed a phylogenetically informed analysis to investigate the influence of AS on the current geographical distributions of 111 teleost fish species. Contrary to expectations, we found a negative relationship between absolute latitude range and thermal peak AS in temperate fishes. We found no evidence for an association between thermal range of AS and the range of latitudes occupied for 32 species. Our main results therefore contradict the prevailing theory of a positive link between AS and distribution range in fish.

Experimental and Computational Analyses of Thermal Runaway Behavior of Lithium Ion Pouch Battery at Low Ambient Pressure

Abstract Safety issue concerning “thermal runaway (TR) behavior” of lithium-ion battery (LIB) is one of the core concerns for users. We have studied TR behaviors at various ambient pressures. The thermal runaway onset time (t1) occured in advance at ambient pressure decreasing to 50 kPa from 90 kPa (90, 80, 70, 60, and 50 kPa). At 50 kPa, thermal runaway onset time of LIBs was 177 s earlier than that at 90 kPa. With the decreasing ambient pressure, several values declined, such as battery peak surface temperature, heat release rate (HRR), peak flue gas temperature, and total heat release (THR). Moreover, the peak concentrations of CxHy and CO increased as the ambient pressure decreased, whereas peak concentrations of CO2 and NO showed the opposite trend. Based on the previous studies of the thermal analysis kinetics model of LIBs, a pressure correction factor kp was introduced to establish a prediction model for thermal runaway temperature at low pressure conditions. Based on the model output, the error of thermal runaway onset time t1 could be controlled within ±2 s, and the error of thermal runaway peak temperature Tmax could be controlled within ±2 °C. Our results have been well consistent with the results of simulation, and have been beneficial to further reveal LIBs thermal runaway behavior under low ambient pressure.

Purification, crystal structure and properties of azoxytriazolone (AZTO)

In this work, the azoxytriazolone (AZTO) was synthesized by electrochemical reduction 5-nitro-1,2,4-triazol-3-one (NTO) under different types of electrolytes which were Na2SO4 and H2SO4. By comparing the yield of AZTO/azoTO synthesized under different electrolyte conditions, the work found that sulfuric acid as the electrolyte has a positive effect on the synthesis of AZTO. On this basis, the high-concentration AZTO was prepared by regulating the concentrations of sulfuric acid (0.05M, 0.1M, 0.5M, 1M). Finally, by introducing an appropriate amount of NaOH, we successfully achieved the separation and purification of AZTO from the mixture of AZTO and azoTO. In addition, single crystal AZTO was also prepared in this experiment to test its crystal structure, which illustrated that the crystal density of AZTO is 1.902 g/cm3 at 193 K, belonging to the monoclinic crystal system with space group P21/n. The thermal properties results of AZTO showed that the thermal stability properties of AZTO were affected by AZTO/azoTO ratio, and the thermal decomposition peak of pure AZTO is 352°C when the content of azoTO is zero. On the contrary, the BAM susceptibility tester test demonstrated the impact susceptibility is 30 J and the friction susceptibility is greater than 360 N of AZTO, which are unaffected on azoTO. According to the K-J empirical formula, the blasting velocity and detonation pressure of AZTO were 7713.5 m/s and 26.1 GPa, respectively. The influences of different types of electrolytes and sulfuric acid concentrations on the yield of AZTO were evaluated, and the relevant reaction mechanism of electrochemical synthesis of AZTO and azoTO was supplemented in this paper.

Dual-Encapsulated Nanocomposite for Efficient Thermal Buffering in Heat-Generating Radiative Cooling.

Radiative cooling has been considered an innovative passive method to resolve the problem of overheating of electronic devices. However, it is inefficient for cooling huge heat generation components. Herein, we report a dual-encapsulated nanocomposite (DEN) by integrating radiative cooling and phase-change materials (PCMs) for thermal buffering in heat-generating radiative cooling. The leak of PCMs is avoided by a simple dual-encapsulated structure with a three-dimensional (3D) interconnected cellular-like network structure and radiative cooling layer on the surface, 75% superior to the state-of-the-art single encapsulation designs. Additionally, our DEN not only shows outstanding optical properties with strong solar reflection (R̅solar = 0.96) and IR-selective emission (ε̅8-13 μm = 0.94 and ηε = 1.15) but also exhibits high phase-change enthalpy (ΔHm = 192.2 J/g, ΔHc = 175.7 J/g), enabling remarkable radiative cooling capability and desirable thermal energy peak shaving and valley filling effect. Outdoor experiments demonstrate that DEN achieves a temperature drop up to 23 °C compared to the control group without DEN coverage when electronics generate heat. This dual-encapsulated nanocomposite provides a novel strategy and solution for outdoor passive thermal management.

Characteristics of Hybrid Nanolubricants for MQL Cooling Lubrication Machining Application

Efficient and effective lubricants have great application prospects in the manufacturing industries. Minimum quantity lubrication (MQL) machining with low flow rate of nanolubricants is investigated for cooling and lubrication during the process. This paper investigates the characterization of graphene-mixed aluminium oxide (G-Al2O3) hybrid nanomixture spent lubricants for MQL machining purposes. The main advantage of this method is to reduce the disposal lubricants to develop high-performance cooling-lubrication by using nanolubricants of G-Al2O3 nanoparticles in different volume composition ratios at a constant 1.0% volume concentration in a base liquid mixture of 40% spent lubricants. Before conducting the measurements of the nanolubricants’ thermal conductivity and dynamic viscosity, the nanolubricants were homogenous and stable. The tribological performance of all ratios was evaluated by using a four-ball wear tribotester machine. The thermal conductivity peak value for the G-Al2O3 hybrid nanolubricant was obtained and the highest enhancement, up to 29% higher than the base liquid solution, was obtained. The dynamic viscosity variation for all ratios was lower than the 40:60 ratio. The properties enhancement ratio suggests that G-Al2O3 hybrid nanolubricants with 1.0% volume concentration aid in the heat transfer, especially for ratios of 60:40 and 20:80. The lowest coefficient of friction (COF) for a ratio of 60:40 was obtained to be 0.064, with 45% enhancement as compared to the base liquid solution. In conclusion, optimum ratios for G-Al2O3 hybrid nanolubricants were determined to be 20:80 and 60:40. Regarding the properties enhancement ratio, the combination of enhanced thermophysical and tribological properties had more advantages for cooling lubrication application.

3D Electron-Rich ZIF-67 Coordination Compounds Based on 2-Methylimidazole: Synthesis, Characterization and Effect on Thermal Decomposition of RDX, HMX, CL-20, DAP-4 and AP

ZIF-67 is a three-dimensional zeolite imidazole ester framework material with a porous rhombic dodecahedral structure, a large specific surface area and excellent thermal stability. In this paper, the catalytic effect of ZIF-67 on five kinds of energetic materials, including RDX, HMX, CL-20, AP and the new heat-resistant energetic compound DAP-4, was investigated. It was found that when the mass fraction of ZIF-67 was 2%, it showed excellent performance in catalyzing the said compounds. Specifically, ZIF-67 reduced the thermal decomposition peak temperatures of RDX, HMX, CL-20 and DAP-4 by 22.3 °C, 18.8 °C, 4.7 °C and 10.5 °C, respectively. In addition, ZIF-67 lowered the low-temperature and high-temperature thermal decomposition peak temperatures of AP by 27.1 °C and 82.3 °C, respectively. Excitingly, after the addition of ZIF-67, the thermal decomposition temperature of the new heat-resistant high explosive DAP-4 declined by approximately 10.5 °C. In addition, the kinetic parameters of the RDX+ZIF-67, HMX+ZIF-67, CL-20+ZIF-67 and DAP-4+ZIF-67 compounds were analyzed. After the addition of the ZIF-67 catalyst, the activation energy of the four energetic materials decreased, especially HMX+ZIF-67, whose activation energy was approximately 190 kJ·mol-1 lower than that reported previously for HMX. Finally, the catalytic mechanism of ZIF-67 was summarized. ZIF-67 is a potential lead-free, green, insensitive and universal EMOFs-based energetic burning rate catalyst with a bright prospect for application in solid propellants in the future.

Thermal performance analysis of a passive hybrid earth-to-air heat exchanger for cooling rooms at Mexican desert climate

This research incorporates two passive technologies selected to offer thermal comfort conditions in a room exposed to extreme desert climatic conditions (Hermosillo, Sonora, Mexico). On the one hand, a rectangular earth-air heat exchanger assisted with PCM (REAHE + PCM) is implemented. Its job is to supply cooled air to the room at temperatures below the comfort temperature. On the other hand, a room with PCM on its ceiling (room + PCM) is proposed, to reduce the thermal load towards the room and shift the thermal peak load, acting as thermal insulation. Hoping that the benefits of this combination of passive technologies provide the thermal comfort conditions required in a building in this region and thereby eliminate or reduce the consumption of electrical energy in conventional refrigeration systems. This article reports a detailed transient study of the thermal behavior of a passively cooled room. The effect of position, thickness, latent heat, and phase change temperature of the PCM in the room was investigated. Also, the different room configurations reported the time evolution of heat fluxes, temperatures, coefficient of performance (COP), and liquid fraction. A comparison between the proposed system and a room without PCM was made. Adding PCM to the roof can drop the peak heat flux in the ceiling by up to 33%. It was found that the most favorable system was with the PCM placed on the top of the room with a thickness between 1.5 cm and 2.0 cm. The best configuration kept an average room temperature of 0.6 K below the comfort temperature. The maximum temperature in the room only exceeded the comfort temperature by 0.33 K. The average COP varied between 264 and 288 for the room systems, while the average COP for the REAHE-PCM was 307. This combination of technologies is satisfactory for the climatic conditions studied.

Non-Isocyanate Polyurethane Bio-Foam with Inherent Heat and Fire Resistance.

Polyurethanes (PUs) are versatile and widespread, particularly as flexible and rigid foams. To avoid isocyanates and other toxic reagents required for synthesis, such as phosgene, alternative synthetic routes have been utilized to produce non-isocyanate polyurethanes (NIPUs). A thermally and flame-resistant rigid NIPU was produced from environmentally benign and bio-sourced ingredients, requiring no catalyst or solvents. A foamed structure was obtained by the addition of glutaraldehyde and four different carboxylic acids: malic acid, maleic acid, citric acid, and aconitic acid. The resulting morphology, thermal degradation, and flame resistance of each foam were compared. The properties vary with each carboxylic acid used, but in each case, peak thermal degradation and peak heat release are postponed by >100 °C compared to commercial rigid PU foam. Furthermore, in a butane torch test, NIPU foams exhibit an 80% higher remaining mass and a 75% reduction in afterburn time, compared to commercial polyurethane. This bio-based polyurethane eliminates the hazards of traditional PUs, while imparting inherent thermal stability and flame resistance uncharacteristic of conventional foams.

Ultrahigh temperature metamorphism recorded in the Lüliang Complex, Trans-North China Orogen: P–T–t evolution and heating mechanism

Identifying ultrahigh temperature (UHT) metamorphism from hot orogens and establishing its pressure–temperature–time (P–T–t) path will provide notable insights into tectonic evolution and heat source (mantle/mafic magma vs crustal radioactive elements) responsible for the extreme conditions. We report here a combined investigation of petrography, mineral chemistry, phase equilibria modelling, geothermobarometer calculation, geochronology and heat source for mafic and pelitic granulites from the Lüliang Complex, Trans-North China Orogen (TNCO), a representative Paleoproterozoic hot collisional orogen. The rocks record clockwise P–T paths, including granulite-facies peak and post-peak retrograde stages. Garnet + pyroxene + high-Ti hornblende-bearing assemblage in the mafic granulite and garnet + feldspar + sillimanite-bearing assemblage in the pelitic granulite constrain the thermal peaks at 8.2–10 kbar and 880–959 °C, suggesting UHT conditions. Zircon and monazite U–Pb dating, hornblende 40Ar/39Ar dating and Ti-in-zircon thermometer calculation indicate that the rocks may have experienced sluggish retrograde metamorphism from 1.92 to 1.80 Ga, with a cooling rate of 2.0–2.5 °C/Ma. The newly discovered UHT metamorphism, combined with previous geological data, validates a long-lived tectono-thermal evolution from 1.97 to 1.80 Ga in the TNCO. The calculated heat flow produced by the decay of radioactive elements in the thickened crust is 37–77 mW/m2 (with an average of 56 mW/m2), which is high enough to achieve UHT conditions. Therefore, we suggest that radioactive heating can be an important heating mechanism for UHT metamorphism in a long-lived hot orogen like the TNCO.

A Review on the Impact of High-Temperature Treatment on the Physico-Mechanical, Dynamic, and Thermal Properties of Granite

Temperature changes have significant effects on rock properties. The changes in properties vary for different rocks with different temperature ranges. Granite is an igneous type of rock that is common in India and is frequently used for construction and domestic purposes. Granite is mainly composed of quartz and feldspar and shows a considerable response to temperature changes and is the subject of this paper. A comprehensive review of the published literature has been conducted in this paper. Comparison of the findings of such works in terms of the impact of temperature changes on basic mechanical, physical, and thermal properties of granite, viz. thermal damage, density, p-wave velocity, compressive strength, peak stress, peak strain, and Young’s modulus from room temperature to 1000 °C has been conducted. The published data of different researchers have been utilized for such comparison. The study revealed that there is a significant departure in response to the rock recorded by various researchers, which may be due to the constitution of the rocks analyzed or experimental procedures. This points to the standardization of such tests. The main reason for changes in the properties of granite has also been discussed. Consequently, the findings of this state-of-the-art demonstrate that the heating effects of granite on its physical and mechanical properties become increasingly pronounced with increasing pick temperatures. The purpose of this article is to provide readers with an extremely well-structured, seamless environment that facilitates a critical assessment of granite in order to determine its thermal profile.

Late Mesoproterozoic to early Neoproterozoic evolution of the Meghalaya gneissic complex, NE India: significance in Rodinia assembly

ABSTRACT The Meghalaya Gneissic Complex (MGC) of northeast India is a little-studied high-grade metamorphic terrain, located close to the Late Palaeoproterozoic to early Neoproterozoic orogenic front. We include mapping, petrography, mineral chemistry, geochemistry, phase equilibria modelling, and U-Th-total Pb monazite geochronology to investigate the evolutionary history of deformed and metamorphosed ortho- and para-gneisses from the central MGC. The metapelite and metamafic rocks of the MGC are folded to E-W upright, antiforms-synforms; and intruded by charnockites during progressive deformations. Reconstructing the metamorphic history of pelite (garnet-cordierite granulite) and two pyroxene granulite, using a TiMnNCKFMASH and TiNCKFMASHO system, reveals a clockwise P–T path where the peak metamorphism was associated with mid crustal burial heating to granulite facies (~825°C and 5.5 to 6.5 kbar) and subsequent cooling with a minor decompression (~ 816°C and 5.3 kbar). Chemically zoned monazites were grown episodically during 1035 ± 13 Ma (n = 21), 976 ± 14 Ma (n = 16), and 494 ± 14 Ma (n = 26). The granulite metamorphism here initiated at 1035 ± 13 Ma and reached thermal peak at 976 ± 14 Ma. This contribution emphasizes the importance of late Mesoproterozoic to early Neoproterozoic metamorphic evolution of the MGC related to the collision of North and South Indian cratonic blocks. The studied P-T path differs from the previously reported Meso- to early Neoproterozoic paths of Central and Western India and close to Western Australia. This finding further explains the change in the early Neoproterozoic collisional pattern of the Central Indian Suture in extreme east (near MGC) and its significance in reconstructing the western Rodinia.