Trace elements in magmatic and hydrothermal quartz:Implications on the genesis of the Xingluokeng Tungsten Deposit,South China

The Xingluokeng deposit is the largest gran-ite-related tungsten deposit within the Wuyi metallogenic belt in South China.The Xingluokeng intrusion primarily consists of porphyritic biotite granite,biotite granite,andfine-grained granite.The deposit is represented by veinlet-disseminated mineralization with K-feldspathization and biotitization,alongside quartz-vein mineralization with gre-isenization and sericitization.This study investigates in-situ analyses of quartz compositions from both the intrusion and hydrothermal veinlets and veins.Trace element correlations indicate that trivalent Al^(3+)and Fe^(3+)replace Si^(4+)within the quartz lattice,with monovalent cations(such as Li^(+),Na^(+),and K^(+))primarily serving as charge compensators.Low Ge/Al ratios(<0.013)of quartz from granites suggest a mag-matic origin.The low Al/Ti and Ge/Ti ratios,accompanied by high Ti contents in quartz,suggest that the porphyritic biotite granite and biotite granite are characterized by rela-tively low levels of differentiation and high crystallization temperatures.In contrast,thefine-grained granite exhibits a higher degree of fractionation,lower crystallization tem-peratures,and a closer association with tungsten miner-alization.Ti contents in quartz from quartz veins indicate Qz-Ⅰformed at temperatures above 400°C,while Qz-Ⅱto Qz-Ⅴformed at temperatures below 350°C.Variations in different generations of quartz,as indicated by Al content and(Al+Fe)/(Li+Na+K)ratio,suggest that Qz-Ⅰprecipi-tated from a less acidicfluid with a stable pH,whereas Qz-Ⅱto Qz-Ⅴoriginated from a more acidicfluid with notable pH variations.Consequently,alkaline alteration and acidic alteration supplied the essential Ca and Fe for the precipita-tion of scheelite and wolframite,respectively,highlighting a critical mechanism in tungsten mineralization at the Xin-gluokeng deposit.

Jet formation and penetration performance of a double-layer charge liner with chemically-deposited tungsten as the inner liner

This paper proposes a type of double-layer charge liner fabricated using chemical vapor deposition(CVD)that has tungsten as its inner liner.The feasibility of this design was evaluated through penetration tests.Double-layer charge liners were fabricated by using CVD to deposit tungsten layers on the inner surfaces of pure T2 copper liners.The microstructures of the tungsten layers were analyzed using a scanning electron microscope(SEM).The feasibility analysis was carried out by pulsed X-rays,slug-retrieval test and static penetration tests.The shaped charge jet forming and penetration law of inner tungsten-coated double-layer liner were studied by numerical simulation method.The results showed that the double-layer liners could form well-shaped jets.The errors between the X-ray test results and the numerical results were within 11.07%.A slug-retrieval test was found that the retrieved slug was similar to a numerically simulated slug.Compared with the traditional pure copper shaped charge jet,the penetration depth of the double-layer shaped charge liner increased by 11.4% and>10.8% respectively.In summary,the test results are good,and the numerical simulation is in good agreement with the test,which verified the feasibility of using the CVD method to fabricate double-layer charge liners with a high-density and high-strength refractory metal as the inner liner.

Re-Os Dating of Molybdenite from the Yaogangxian Tungsten Deposit,South China,and Its Geological Significance

The Yaogangxian tungsten deposit is located in the central part of the Nanling polymetailic metallogenic province. The orebodies occur as veins. Wolframite and molybdenite are the dominant ore minerals. Two samples were selected for molybdenite Re-Os dating in order to elucidate the timing of mineralization. Re-Os datings of molybdenite from quartz-woiframite veins and disseminated in granite yield ages of 153±7 Ma and 163.2±4.2 Ma respectively. The results indicate that the Yaogangxian tungsten deposit is the product of large-scale metallogenesis in the middle Yanshanian period in South China, and that the evolution from late magmatic to postmagmatic hypothermal mineralization occurred at about 10 Ma. The rhenium content of molybdenite in the Yaogangxian tungsten deposit suggests that the ore materials originated from the crust.

Metallogenic Mechanism and Tectonic Setting of Tungsten Mineralization in the Yangbishan Deposit in Northeastern China

The Yangbishan iron-tungsten deposit in the Shuangyashan area of Heilongjiang Province is located in the center of the Jiamusi Massif in northeastern China. The rare earth element and trace element compositions of the scheelite show that it formed in a reducing environment and inherited the rare earth element features of the ore-forming fluid. The geochemical characteristics of the gneissic granite associated with the tungsten mineralization show that the magma formed in this reducing environment and originated from the partial melting of metamorphosed shale that contained organic carbon and was enriched with tungsten. In addition, in situ Hf isotopic analysis of zircons from the gneissic granite indicates that they probably originated from the partial melting of a predominantly Paleo-Mesoproterozoic crustal source. According to LA-ICP-MS zircon dating, the Yangbishan ore- related gneissic granite has an Early Paleozoic crystallization age of 520.6 ＋ 2.8 Ma. This study, together with previous data, indicates that the massifs of northeastern China, including Erguna, Xing＇an, Songliao, Jiamusi, and Khanka massifs, belonged to an orogenic belt that existed along the southern margin of the Siberian Craton during the late Pan-African period. The significant continental movements of this orogeny resulted in widespread magmatic activity in northeastern China from 530 Ma to 470 Ma under a tectonic setting that transitioned from compressional syn-collision to extensional post- collision.

Isotopic Chronological Study of the Huangsha-Tieshanlong Quartz Vein-Type Tungsten Deposit and Timescale of Molybdenum Mineralization in Southern Jiangxi Province,China

The Huangsha-Tieshanlong quartz-vein tungsten polymetallic ore deposit, located in the northern Pangushan-Tieshanlong tungsten ore field in eastern Ganxian-Yudu prospecting areas of the Yushan metallogenic belt, is a well-known tungsten deposit in southern Jiangxi province, China. SHRIMP-determined dating of zircons from the Tieshanlong granite yields ages of 168.1±2.1 Ma （n=11, MSWD-1.3）. Rhenium and osmium isotopic dating of molybdenite from the Huangsha quartz-vein tungsten deposit determined by ICP-MS yields a weighted average ages of 153-3 Ma and model ages of 150.22.1 Ma - 155.4-2.3 Ma. The age of the Huangsha tungsten deposit is 10 to 15 Ma later than the Tieshanlong granite, which shows that there might have been another early Late Jurassic magmatic activity between 150 and 160 Ma, a process which is closely related with tungsten mineralization in this area. The Tieshanlong granite, the Hnangsha tungsten deposit and the Pangushan-Tieshanlong ore field were all formed around 150-170 Ma, belonging to products of a Mesozoic second large-scale mineralization. According to the collected molybdenite Re-Os dating results in southern Jiangxi province, the timescale of the associated molybdenum mineralization is 2-6 Ma in the tungsten deposit and the timescale of independent molybdenum mineralization is 1-4 Ma, implying the complexity of tungsten mineralization. Times of molybdenum mineralization are mainly concentrated in the Yanshanian, which includes three stages of 133-135 Ma, 150-162 Ma, and 166-170 Ma, respectively. The 150-162 Ma-stage is in accordance with ages of large-scale WoSn mineralization, which is mainly molybdenum mineralization characterized by associated molybdenum mineralization with development of an even greater-intensity independent molybdenum mineralization. Independent molybdenum mineralization occurred before and after large-scale W-Sn mineralization, which indicates that favorable prospecting period for molybdenum may be in Cretaceous and early late Jurassic.

Timing and Tectonic Setting of the Gaoaobei TungstenMolybdenum Deposit in Nanling Range, South China

The Gaoaobei tungsten-molybdenum deposit is a newly discovered large-scale quartzvein-type deposit in the Nanling metallogenic belt in South China.The ore bodies are hosted in the Indosinian granites and the Cambrian Xiangnan Group slates and are controlled by NWW-oriented faults,which are obviously different from the“five-story building”model in southern Jiangxi Province.The magmatic rocks in the study area are dominated by medium-to coarse-grained biotite monzogranite,with a few NW-oriented fine-grained granite dykes.The medium-to coarse-grained biotite monzogranite and fine-grained granite dykes have zircon U-Pb ages of 229.4±1.9 Ma(MSWD=1.5)and 164.9±3.3 Ma(MSWD=0.75),respectively,corresponding to the Indosinian and Yanshanian magmatism.The monzogranites have higher contents of FeO,CaO,K2O,P2O5,and TiO2,while the granite dykes have slightly higher contents of SiO2,Al2O3,MnO,and Na2O.Their A/CNK values are 1.11-1.75 and 1.19-2.25,and the contents of CIPW normative corundum are 1.71%-6.66%and 2.41%-9.50%,suggesting both the monzogranites and granite dykes are S-type granite.The total amount of rare earth elements in the monzogranites(from 84.7 ppm to 129 ppm)is slightly lower than that in the granite dykes(from 128 ppm to 133 ppm).The Eu/Eu*values range from 0.12 to 0.30 in monzogranites and from 0.0011 to 0.0013 in granite dykes,indicating the fine-grained granites underwent more intense fractional crystallization.The monzogranite and granite dykes have high 87Sr/86Sri values of 0.7169-0.7193 and 0.72825-0.72880,lowεNd(t)values ranging from-10.2 to-9.6 and from-11.5 to-11.4,and TDM2 ages of 1835-1785 and 1957-1946 Ma,respectively.These isotope data indicate their origin from the remelting of the Paleoproterozoic crustal materials.Combined with regional geology,it is concluded that the medium-to coarse-grained biotite monzogranite was formed in a post-collisional extensional environment.In addition,40Ar-39Ar dating of the greisen type tungsten-molybdenum ore gave consistent plateau age of 164.0±1.2 Ma,isochronal age of 162.0±2.4 Ma and anti-isochronal age of 161.4±1.8 Ma.Combined with the published molybdenite Re-Os age,the Gaoaobei tungsten-molybdenum deposit was formed at~164 Ma,which is inferred to be genetically related to the contemporaneous finegrained granite dykes(165 Ma).The deposit was likely formed during the large-scale magmatism and mineralization event in the early Yanshanian of the Nanling Range in an intra-continental extensional environment caused by the subduction of the paleo-Pacific plate.The late and small granite dykes within the large granite plutons thus require further attention during mineral prospecting in the regions.

A Preliminary Review of Metallogenic Regularity of Tungsten Deposits in China

Tungsten ore resources are abundant in China with relatively complete types of deposits. Skarn type and quartz vein type deposits are dominated in the tungsten resources, whereas quartz vein type wolframite deposits are most important in terms of exploitation and utilization. Skarn type tungsten deposits are concentratedly distributed in the central Nanling region, such as South Hunan, South Anhui and the eastern Qinling region, while quartz vein type tungsten deposits occur mainly in South China, such as West Fujian, South Jiangxi, North Guangdong and South Hunan. The most important metallogenic epoch of tungsten is the Mesozoic, while the metallogenic tectonic setting is featured by an intracontinental environment after orogeny with sever tectonic movements, deep-seated faults and frequent magmatic activities, especially Mesozoic granitoids closely related to tungsten-tin mineralization. 22 metallogenic series of ore deposits characterized by or significantly related to tungsten were defined based on precise statistic information of 1199 tungsten mining areas and thorough the summary of metallogenic regularities. Based on studies of the metallogenic regularity of tungsten deposits, skarn type （or greisen type）, quartz vein type and massif-type of tungsten deposits are thought to be the key prediction types. 65 tungsten-forming belts and 22 key ore concentration areas were ascertained and a distribution map of tungsten-forming belts of China was compiled, which provided a theoretical basis for evaluation and prediction of potential tungsten resources.

Pore Formation Mechanism in W-C Hard Coatings Using Directed Energy Deposition on Tungsten Alloy

Porosity is a common phenomenon and can significantly hinder the quality of the coating.Here,the pore formation mechanism and the characteristics of the single tracks of the W-C coating using directed energy deposition(DED)are systematically investigated.The forming quality of the tracks,the distribution of the pores,and the elemental distribution near the pores are analyzed by the observations of the cross-sections of the tracks.The temperature field of the melt pool is discussed comprehensively to reveal the pore formation mechanism.The results confirm that Ni and Co evaporated during the DED process due to the high temperature of the melt pool.Pores were continuously produced adjacent to the fusion line when the melt pool was about to solidify since the temperature at the solidification front was higher than the boiling point of Ni.The vaporization area at the fusion line was proposed,where Ni could also evaporate at the time the melt pool started to solidify.The relationship between the solidification rate,the size of the vaporization area and the DED parameters(laser power and scanning speed)was established to discuss the causes of severe pores above the fusion line.This work contains a practical guide to reduce or eliminate the porosity in the coating preparation process on the surface of the tungsten alloy.

INDUCTION PLASMA REACTIVE DEPOSITION OF TUNGSTEN CARBIDE FROM TUNGSTEN METAL POWDER

Experimental results on the primary carburization reaction between the tungsten powder and methane in the induction plasma, and the secondary carburization of the deposit on substrate at high temperature are reported. Optical microscopy and scanning electron microscopy were used to examine the microstructures of starting tungsten powder, carburized powder, and deposit. X-ray diffraction analysis, thermal gravimetric analysis and microhardness measurement were used to characterize the structures and properties of the powder and the deposit. It is found that the primary carburization reaction in the induction plasma starts from the surface of tungsten particles when the particles are melted. Tungsten particles are partially carburized inside the reactive plasma. Complete carburization is achieved through the secondary carburization reaction of the deposit on substrate at high temperature.

Mineral Geochemical Compositions of Tourmalines and Their Significance in the Gejiu Tin Polymetallic Deposits, Yunnan, China

The Gejiu tin polymetallic deposits are located in the southeastern part of Yunnan Province in China. A detailed electronic microprobe study has been carried out to document geochemical compositions of tourmalines from the deposits. The results indicate a systematic change of mineral geochemical compositions, which might be used as a mineral geochemical tracer for post-magmatic hydrothermal fluid, basin fluid and their mixture. The tourmalines from granite are schori with Fe/ （Fe＋Mg） ratios of 0.912-1.00 and Na/（Na＋Ca） ratios of 0.892-0.981. Tourmalines as an inclusion in quartz from the ore bodies are dravite with Fe/（Fe＋Mg） ratios of 0.212-0.519 and Na/（Na＋Ca） ratios of 0.786--0.997. Tourmalines from the country rocks are dravite with Fe/（Fe＋Mg） ratios of 0.313--0.337 and Na/（Na＋Ca） ratio of 0.599-0.723. Tourmalines from cassiterite-tourmaline veins that occur in crannies within the country rocks show distinct optical zoning with alternate occurrence of dravite and schorl, Fe/（Fe＋Mg）=0.374-0.843, Na/（Na＋Ca）=0.538-0.987. It suggests that schorl in granite and dravite in carbonatite are related to magmatic fluid and basin fluid respectively. When magmatic fluid rose up and entered into crannies of the country rocks, consisting mainly of carbonatite, basin fluid would be constantly added to the magmatic fluid. The two types of fluid were mixed in structural crannies of the sedimentary basin accompanied with periodic geochemical oscillations to form material records in chemical composition zonings of tourmalines.

Effect of process parameters on induction plasma reactive deposition of tungsten carbide from tungsten metal powder

Tungsten carbide deposit was made directly from tungsten metal powder through the reaction with methane in radio frequency induction plasma. Effect of major process parameters on the induction plasma reactive deposition of tungsten carbide was studied by optical microscopy, scanning electron microscopy, X ray diffraction analysis, water displacement method, and microhardness test. The results show that methane flow rate, powder feed rate, particle size, reaction chamber pressure and deposition distance have significant influences on the phase composition, density, and microhardness of the deposit. Extra carbon is necessary to ensure the complete conversion of tungsten metal into the carbide.

Deposition of tungsten-titanium carbides on surface of diamond by reactive PVD

The coatings of W-Ti carbides on the surface of diamond was obtained by using physical vapor deposition (PVD), during which WO3 powders pre-treated with hydrofluoric acid were reduced by titanium hydride in vacuum at 850 ℃. The resistance of diamond to corrosion at high-temperature was investigated. The formation of W-Ti carbides on the surface of diamond was verified by X-ray diffraction analysis, the interface state between diamond and matrix in metaLbase diamond composite was observed by scanning electron microscope. The results showed that the carbide coating is easy to be formed at low deposition temperature on the surface of diamond, while the resistance of diamond to corrosion at highutemperature and the strength of bonding between diarnond and metal matrix are effectively improved.

Electrochemical Deposition and Nucleation of Aluminum on Tungsten in Aluminum Chloride-Sodium Chloride Melts

Electrochemical deposition and nucleation of aluminum on tungsten electrode from AlCl3-NaCl melts were studied by cyclic voltammetry, chronopotentiometry and chronoamperometry. Cyclic voltammetry and chronopotentiometry analyses showed that Al （Ⅲ） was reduced at 200℃ in two consecutive steps in an electrolyte of molten AlCl3-NaCl system with a composition 52：48 molar ratio. The current-time characteristics of nucleation aluminum on tungsten showed a strong dependence on overpotentials. Chronoamperometry showed that the deposition process of aluminum on tungsten was controlled by an instantaneous nucleation with a hemispherical diffusion-controlled growth mechanism. The results could lead to a better understanding of the AlCl3-NaCl melt system that has technological importance in electrodeposition of metals as well as in rechargeable batteries.

Geochemical Characteristics of Rare Earth Elements in Gejiu Tin Polymetallic Deposits, Yunnan Province, China

In order to get a better understanding of metallogeny, the geochemical characteristics of REE and trace element for Gejiu tin polymetallic deposits were studied by comparing concentrations of REE and trace elements in different type ores and rocks, including skarn-type ore, bedded-type ore, vein-type ore, altered granite, country rocks. Results of this study indicated that the metallogenic matters for different type ores in the study area might be derived from the same origin source, which may be mainly related to granitic activities. Furthermore, there are some differences in concentrations of REE in different ores due to their different depositional mechanism during that time. LREE concentrations were enriched relatively in the vein-type ores and the bedded-type ores with relatively low total REE concentrations, whereas total REE concentrations were higher in the skarn-type ores with LREE and HREE concentrations in wide variation ranges.

A Preliminary Review of Metallogenic Regularity of Tin Deposits in China

China is rich in tin resources,and contains many types of tin deposits.Among the tin deposit types,the cassiterite-sulfide type,skarn type and quartz vein type occupy a large proportion of tin resources and reserves.From the aspect of exploitation and utilization,the most important types are cassiterite-sulfide type and quartz vein type.The cassiterite-sulfide type tin deposits are mainly located in Northern Guangxi and Eastern Yunnan,skarn type deposits are mainly distributed in the ore-concentration areas of South Hunan in Middle Nanling,and the quartz vein type tin deposits are mainly distributed in South China,such as Western Fujian,Middle Jiangxi,Northern Guangzhou and Southern Hunan.The most important metallogenic epoch for tin deposits is the Mesozoic era.The metallogenic geotectonic background is mainly continental environments after orogeny process,with strong tectonic changes,interlaced deep fracture and frequent magmatism.And the most distinctive feature is the well developed Mesozoic granites,which have a close relationship with tin mineralization.Based on the detailed study of the data from 873 tin deposits in China,this paper summarized the metallogenic regularity of tin deposits,classified 20 important metallogenic series of tin or tin-associated deposits,and inferred that the cassiterite-sulfide type,skarn type,quartz vein type and greisen type are the main prediction types of tin resources.Forty-four tin-mineralization belts were divided,among which,19 belts are the most important.In addition,a series of maps about tin metallogenic belts and tin metallogenic regularity were compiled,aiming to provide theoretical basis for potential estimation and prediction of tin mineral resources.

Characteristics of rare-earth elements (REE),strontium and neodymium isotopes in hydrothermal fluorites from the Bailashui tin deposit in the Furong ore field,southern Hunan Province,China

In this paper the authors present the REE concentrations and Sr and Nd isotopic compositions of fluorites from the Bailashui tin deposit of the Furong ore field,southern Hunan Province. The results showed that the total amount of REE in fluorites is usually low,ranging from 0.705 to 8.785 μg/g with the chondrite-normalized REE dis-tribution patterns similar to those of the Qitianling granites in the study area,characterized by LREE-enrichment patterns with pronounced negative Eu anomalies. The fluorites vary in Sr isotopic composition within the range of 0.7083-0.7091,the values are lower than those of the granites and higher than those of the host carbonate rocks in this area. The εNd(t) values of fluorites vary between -9.4 and +10.3,revealing that both the crust-and mantle-source materials were involved in the ore-forming hydrothermal fluids. Combined with previous studies on this ore deposit,the Bailashui tin deposit is temporally and spatially closely related with granitic magmatism in this area. The hydro-thermal fluorites are the product of fluid/rock interactions between granitic magmatic hydrothermal fluid and marine carbonate rocks. The REE and F in the ore-forming fluid were derived from the granites,whereas Sr in the ore-forming fluid came mainly from the granitic magmatic hydrothermal fluid and marine carbonate rocks,although variations in Sr isotopic composition cannot be explained by a simple mixture of these two end-members. Evidence demonstrated that the ore-forming fluids are of crustal-mantle mixing origin,but that the fluids were probably in-completely homogenized and this may be caused by inhomogeneous mixing of the fluids of different sources.

Diversity of Mineralization and Spectrum of the Gejiu Superlarge Tin-Copper Polymetallic Deposit,Yunnan,China

The Gejiu （个旧） deposit is a superlarge tin-copper polymetallic ore-forming concentration area characterized by excellent metallogenic geological settings and advantageous ore-controlling factors. The deposit displays diverse mineralization properties due to different minerals and mineral deposit types. Based on the principal metallogenic factors, metallogenic mechanisms, mineralized components, and occurrence of mineral deposits or ore bodies, the Gejiu mineral district can be divided into 2 combinations of metallogenic series, 4 metallogenic series, 8 subseries, and 27 mineral deposit types. Spatial zonality is evident. The distribution regularity of the elements in both plane and section is Be-W, Sn （Cu, Mo, Bi, Be）-Sn, Pb, Ag-Pb, Zn around a granitic intrusion. The metallogenic epoch is mainly concentrated in the late Yanshanian. During this period, large-scale metallogenic processes related to movement caused by tectonics and magmatism occurred, and a series of magmatic hydrothermal deposits formed. The ore-forming processes can be divided into 4 stages： the silicate stage, the oxide stage, the sulphide stage, and the carbonate stage. Based on the orderliness and diversity （in terms of time, space, and genesis） of the mineralization, the authors have developed a comprehensive spectrum of ore deposits in the Gejiu area. This newly proposed diversity of mineralization and the spectrum developed in this work are useful not only for interpreting the genesis of the Gejiu deposit but also for improving mineral exploration in the area, and in particular, for finding large deposits.

Cassiterite U-Pb Date of the Yangbin Porphyry Tin Deposit in Zhejiang and its Geological Significance

Objective The Yangbin porphyry tin deposit in Taishun County of Zhejiang Province is one of the few porphyry-type tin deposits in South China, which is located in the middle portion of the Mesozoic volcanic active belt on the southeastern coast of China. The Yangbin granite porphyry is closely related to the tin mineralization in this region. Based on petrologic and Sr-Nd-Pb isotopic

Oxygen Isotope Studies of Wolframite in Tungsten Ore Deposits of South China

Based on the oxygen isotopic compositions of 133 wolframite samples and 110 quartz sampleseollected from 30 tungsten ore deposits in south China,in conjunction with δD values and other data,thesc deposits can be divided into four types. （l）Reequilibrated magmatic water-hydrothermal tungsten ore deposits. The δ18O values ofwolframite and quartz samples from this type of tungsten ore deposits are about +5-+12‰,respectively.The calculated δ（18）OH2O values of ore fluids in equilibrium with quartz are about+65‰,and the δDH2O values of fluid inclusions in quartz range from -40 to-70‰. （2）Meteoric water-hydrothermal tungsten ore deposits.Theδ18O values of wolframite in this type oftungsten dePosits are around-1‰. （3）Stratiform tungsten ore deposits.In these deposits,theδ18O values of quartz and wolframite areabout+17 and+3‰,respectively.It is considered that these stratiform tungsten ore deposits aregenetically related to submarine hot—spring activities。 （4）Complex mid-hydrothermal tungsten ore deposits.These tungsten ore deposits arecharacterized by multi-staged mineralization.The δ18O values of early wolframite are around+5‰,butof later wolframite are lower than+4‰,indicating that the early wolframite was precipitated fromreequilibrated magmatic water-hydrothermal solutions and the late one from the mixture ofhvdrothermal solutions with meteoric waters or mainly from meteoric waters, Based on the δ18O values of the coexisting quartz and wolframite and temperature data,twocalibration equilibrium curves have been constructed,and the corresponding equations have beenObtained: 1000 lnaQ-Wf=2.565×107T-2—7.28×l04T-1+57.27 1000 In aWf-H20=-2.285×107T-2+7.49×104T-1-61.79.