Recognition of Ophiolite Belt and Granulite in Northern Area of Mian－Lue， Southern Qinling， China and Their Implication

ＲｅｃｏｇｎｉｔｉｏｎｏｆＯｐｈｉｏｌｉｔｅＢｅｌｔａｎｄＧｒａｎｕｌｉｔｅｉｎＮｏｒｔｈｅｒｎＡｒｅａｏｆＭｉａｎ－Ｌｕｅ，ＳｏｕｔｈｅｒｎＱｉｎｌｉｎｇ，ＣｈｉｎａａｎｄＴｈｅｉｒＩｍｐｌｉｃａｔｉｏｎ￥ＸｕＪｉｆｅｎｇ（Ｄｅｐａｒｔｍｅｎｔｏｆ...

Granulite Genesis and Tectonic Evolution in Tongbai Area:Single Zircon Evaporation Ages and Nd Isotopic Geochemistry

ＩＮＴＲＯＤＵＣＴＩＯＮＴｏｎｇｂａｉａｒｅａｉｎＣｅｎｔｒａｌＣｈｉｎａｉｓａｎｉｍｐｏｒｔａｎｔｒｅｇｉｏｎｆｏｒｓｔｕｄｙｉｎｇｇｅｎｅｓｉｓｒｅｌａｔｉｏｎｂｅｔｗｅｅｎＱｉｎｌｉｎｇｏｒｏｇｅｎｉｃｂｅｌｔａｎｄＤａｂｉｅｏｒｏｇｅｎｉｃｂ...

Garnet-bearing Granulite Facies Rock Xenoliths from Late Mesozoic Volcaniclastic Breccia, Xinyang, Henan Province

This paper presents the primary results of petrologic,mineralogical and petrochemical studies of garnet beating granulite facies rock xenoliths from Xinyang, Henan Province. These xenoliths, which are found in a pipe of late Mesozoic volcaniclastic breccia, are of high density (3.13-3.30 g/cm3) and high seismic velocity (Vp = 7.04-7.31 km/s), being products of underplating of basaltic magmas and had experienced granulite facies metamorphism. The underplating and metamorphism took place before the eruption of the host rock. Petrographical studies and equilibrium T-P calculations show that these xenoliths were captured at a 49 km depth and experienced at least a 16 km uplift before they were captured. The dynamics of the uplift could be related to the continent-continent collision between the North China plate and the Yangtze plate during the Triassic.

Granulite-facies Middle-Lower Crustal Xenoliths from Nushan Alkali Basalt in Northeastern Anhui Province,China

Metamorphic xenoliths within the Nushan alkali basalt of northeastern Anhui (NEA),China ,are from the middle-lower crust.They could be divided into two end-members:basic and acid.Interme-diate xenoliths are scarcely found.Basic two-pyroxene granulites(pyriclasites) were formed at 720-810℃ and 7-8kb.Petrological and geochemical studies indicate that the primary magma of the protoliths of basic granulites was derived from the metasomatized upper mantle, while the pa-rental magma of the acid end-member was probably produced by partial melting of the basic rocks. The protoliths of charnockites and grey gneisses represent respectively the early and late crystallization products of the granitic magma.The Nushan granulites are much different in many aspects from the granulites exposed in the northern part of North China ,which implies the inhomogeneity regarding to the early evolution of the North China terranc.

Important Events and Chronological Framework of the Early Precambrian Granulite Terrain,Northwestern Hebei Province

Based on the chronological data and relevant geological evidence, the chronological framework of the major geological events of the granulite terrain in northwestern Hebei Province and its adjacent areas has been established. Basic lava eruption occurred in the span of 2868-2932 Ma, resulting in the formation of the early crust. The TTG magma emplacement took place c.2761 Ma ago. Subsequently basic magma intruded into the supracrustal rocks at 2650 Ma, resulting in crustal thickening. The thickening was enhanced at 2561-2503 Ma by the widespread intrusions of granodioritic magma. In the period of 2477-2461 Ma charnockite intruded, accompanied by regional granulite facies metamorphism. The second stage of granulite facies metamorphism occurred c. 2300 Ma ago, and finally pink granite intrusions at 2144-2087 Ma resulted in the formation of a granite zone.

Geochronological Study of Caledonian Granulite and High-Pressure Gneiss in the Dabie Mountains

Using the single-zircon evaporation technique and U-Pb method, the authors have conducted an isotope geochonological study of the Huilanshan granulite and Shima garnet-bearing plagioclase gneiss (' country rocks' of the Shima eclogite) in the Dabie Mountains. The study shows that these rocks have peak metamorphic ages of 443-455 Ma, which are essentially consistent with that of the Caledonian high-ultrahigh pressure eclogites. This indicates the existence of the Caledonian collisional orogeny in the Dabie Mountains.

The Sm-Nd Geochronology of the High Pressure Basic Granulite in Laixi, Eastern Shandong

A high pressure basic granulite ultramafic rock belt, which is about 200km long and trends toward NE, occurs in the late Archaean orthogneiss in Laixi Laiyang Qixia area, eastern Shangdong. This belt is located east to the Su Lu UHPM terrane and west to the Archaean rocks of the North China craton, therefore, its geological situation and implication for collision between the North China plate and the Yangtze plate is very important. The analyzed sample of high pressure basic granulite has decreasing pressure metamorphic texture. The mineral assemblage of retrograde metamorphism is of granulite facies. The sample yields an internal mineral whole rock Sm Nd isochron age of 1725Ma. The T(DM) age of whole rock is 2788Ma. These data are very similar to those of high pressure basic granulites in Northern China craton. Considering the petrological and geochemical characteristics and isotopic ages, the high pressure granulite ultramafic rock belt in eastern Shandong is suggested to belong to the North China craton and to be of the early Precambrian lower crust. Their lifting from the lower crustal level is related to collision between the North China plate and the Yangtze plate.

Petrological Investigations and Zircon U-Pb Dating of High Pressure Felsic Granulites from the Yushugou Complex, South Tianshan, China

As a window of insight into the lower crust, high pressure granulite has received much attention since last decade. Yushugou high pressure granulite-peridotite Complex was located in the northeast margin of Southern Tianshan, NW China. Previous ideas agreed that the peridotite unit in Yushugou, combined with the ultramafic rocks in Tonghuashan and Liuhuangshan, represent an ophiolite belt. However, the metamorphic evolution and tectonic mechanism of the Yushugou high pressure(HP) granulite remain controversial. Petrological investigations and phase equilibrium modelling for two representative felsic granulite samples suggest two stages metamorphism of the rocks in Yushugou Complex. Granulite facies metamorphism(Stage Ⅰ) with P-T conditions of 9.8–10.4 kbar at 895–920°C was recorded by the porphyroblastic garnet core; HP granulite facies metamorphism(Stage Ⅱ) shows P-T conditions of 13.2–13.5 kbar at 845–860°C, based on the increasing grossular and decreasing pyrope contents of garnet rims. The Yushugou HP felsic granulites have recorded an anticlockwise P-T path, characterized by the temperature decreasing and pressure increasing simultaneously. The LA-ⅠCP-MS isotopic investigations on zircons from the felsic granulite show that the protolith ages of the granlulites are ～430 Ma, with two age groups of ～390 Ma and 340–350 Ma from the metamorphic rims of zircon, indicating the Stage Ⅰ and Ⅱ metamorphic events, respectively. A tectonic model was proposed to interpret the processes. The investigated felsic granulite was derived from deep rooted hanging wall, with Stage Ⅰ granulite facies metamorphism of ～390 Ma, which may be related to the Devonian arc magmatic intrusion; Stage Ⅱ HP granulite facies metamorphism(340–350 Ma) may due to the involvement of being captured into the subducting slab and experienced the high pressure metamorphism.

A Sm－Nd mineral isochron of mafic granulite from the Sφstrene Island， East Antarctica

任留东，刘小汉ＡＳｍ－ＮｄｍｉｎｅｒａｌｉｓｏｃｈｒｏｎｏｆｍａｆｉｃｇｒａｎｕｌｉｔｅｆｒｏｍｔｈｅＳφｓｔｒｅｎｅＩｓｌａｎｄ，ＥａｓｔＡｎｔａｒｃｔｉｃａ￥ＲｅｎＬｉｕｄｏｎｇ（ＩｎｓｔｄｕｔｅｏｆＧｅｏｌｏｇｙ，ＣｈｉｎｅｓｅＡｃａｄｅｍｙｏ...

Experimental Study of the Melting Reaction and Genetic Mechanism of Mineral Phase Transformation in Granulite Facies Metamorphism

The high-temperature and high-pressure experiment on natural block rock indicates that dehydration-melting of hydrous biotite (Bi) and partial melting of felsic minerals in garnet-biotite-plagioclase gneiss are mainly controlled by temperature, while mineral phase transformation is not only controlled by temperature-pressure conditions but also genetically associated with hydrous mineral dehydration-melting and partial melting of felsic minerals. According to the characteristics of biotite dehydration-melting and garnet transformation reaction, three stages may be distinguished: (1) when the experimental temperature is 700℃, biotite transforms to ilmenite (Ilm) + magnetite (Mt) + H2O and garnet to magnetite (Mt); (2) when the temperature is 730-760℃, biotite is dehydrated and melted and transformed into K2O-rich melt + Ilm + Mt, and garnet, into hypersthene (Hy) + cordierite (Crd); (3) when the temperature is up to or higher than 790℃, biotite is dehydrated and melted and transformed into melt + Hy

Cordierite-bearing granulites from Ihosy,southern Madagascar:Petrology,geochronology and regional correlation of suture zones in Madagascar and India

Madagascar,a major fragment of Gondwana,is mainly composed of Precambrian basenent rocks formed by Mesoarchean to Neoproterozoic tectono-thernial events and recording a Pan-African metamorphic overprint.The Ranotsara Shear Zone in southern Madagascar has been correlated with shear zones in southern India and eastern Africa in the reconstruction of the Gondwana supercontinent.Here we present detailed petrology,mineral chemistry,metamorphic P-T constraints using phase equilibrium modelling and zircon U-Pb geochronological data on high-grade metamorphic rocks from Ihosy within the Ranotsara Shear Zone.Garnet-cordierite gneiss from Ihosy experienced two stages of metamorphism.The peak mineral assemblage is interpreted as garnet+sillimanite+cordierite+quartz+plagioclase+Kfeldspar+magnetite+spinel+ilmenite,which is overprinted by a retrograde mineral assemblage of biotite+garnet+cordierite+quartz+plagioclase+K-feldspar+magnetite+spinel+ilmenite.Phase equilibria nodelling in the system Na2 O-CaO-K2 O-FeO-MgO-Al2 O3-SiO2-H2 O-TiO2-Fe2 O3(NCKFMASHTO)indicates peak metamorphic conditions of 850-960℃ and 6.9-77 kbar,and retrograde P-Tconditions of<740℃ and<4.8 kbar,that define a clockwise P-T path.Near-concordant ages of detrital zircon grains in the garnet-cordierite gneiss dominantly exhibit ages between 2030 Ma and 1784 Ma,indicating dominantly Paleoproterozoic sources.The lower intercept age of 514±33 Ma probably indicates the timing of high-grade metamorphism,which coincides with the assembly of the Gondwana supercontinent.The comparable rock types,zircon ages and metamorphic P-T paths between the Ranotsara Shear Zone and the Achankovil Suture Zone in southern India support an interpretation that the Ranotsara Shear Zone is a continuation of the Achankovil Suture Zone.

Eclogite-High-Pressure Granulite Belt in Northern Edge of the Archean North China Craton

Ｈｉｇｈ－ｐｒｅｓｓｕｒｅｍｅｔａｍｏｒｐｈｉｃｅｃｌｏｇｉｔｅ，ａｓａｗｉｎｄｏｗｏｆｓｔｕｄｙｆｏｒｄｅｐｔｈｌｅｖｅｌｏｆｌｏｗｅｒｍｏｓｔｃｒｕｓｔａｎｄｍａｎｔｌｅ，ｈａｓａｎｉｍｐｏｒｔａｎｔｉｎｄｉｃａｔｉｎｇｓｉｇｎｉｆｉｃａｎｃｅｔ...

The Metamorphism and Its Tectonic Implications of Indosinian High Pressure Granulites from the Badu Complex of the Cathaysia Block, Southwestern Zhejiang Province, South China

The Badu Complex is the oldest metamorphic rock in Cathaysia Block which experienced several episodes of metamorphism Especially indosinian metamorphic reworking in the southwestern Zhejiang Province, South China. The degree of indosinian metamorphism reaches granulite facies. However, there is still insufficient understanding of the characteristics of the Indosinian granulite metamorphism in the Cathaysia and many interpretations of its tectonic significance. Therefore, we present detailed petrology, mineral chemistry and LA-ICP-MS zircon U-Pb age in this paper from pelitic granulites of the Badu Complex, which is composed of "sillimanite + garnet + cordierite + spinel + biotite + k-feldspar" assemblage and garnet pyroxenite with garnet amphibolite which is consists of "garnet + clinopyroxene + orthopyroxene + amphibole + plagioclase". By comprehensive study we get following new findings: Pelitic granulites record four stages of metamorphic mineral assemblages, including prograde(M1), pressure peak(M2), Peak(M3) and post-peak decompressional and then cooling(M4) stages. The prograde M1 assemblage consists of garnet1(core) + staurolite + kyanite + biotite + quartz ± rutile ± chlorite;The pressure peak M2 assemblage consists of garnet1(mantle) + sudoite + rutile + kyanite + corundum + biotite + quartz;The peak M3 have garnet2(rim-mantle) + biotite + sillimanite + quartz ± K-feldspar ± plagioclase ± ilmenite assemblag;the M4 stage is consist of garnet + cordierite + biotite + sillimanite + quartz + ilmenite ± spine ± K-feldspar. The garnet pyroxenite and garnet amphibolites have experienced three stages of metamorphic evolution. Peak high-pressure granulite facies stage M2 consists of garnet + sahlite ± ilmenite ± quartz;Post-peak near isothermal decompression medium granulite facies stage M3 is characterized by typical decompression reaction textures and assemblage of orthopyroxene + plagioclase(An=90–92);amphibolites facies retrograde metamorphic stage M4 is characterized by amphibole + plagioclase(An=33–35) + ilmenite ± sahlite ± quartz mineral assemblage. By means of phase equilibrium simulation and traditional thermobarometer, P-T conditions of 785–820 ℃ and 8.9–9.9 kbar for M3 stage, 780–860 ℃ and 5.7–6.2 kbar for decompressional M4 stage, 705–720 ℃ and 4.5–4.7 kbar for cooling M4 stage in pelitic granulites were obtained. And also 11.6–12.5 kbar and 780–840 ℃ for M2 stage, 7.4–8.2 kbar and 800–880 ℃ for M3 stage, 6.6–7.5 kbar and 500–560 ℃ for M4 stage were obtained in garnet pyroxenite and garnet amphibolite. A clockwise P-T path is confirmed in the two type rocks of the Badu Complex which reflected a near-isothermal decompressional metamorphic process. The peak metamorphism can reach highpressure granulite facies. In addition, the mineral assemblage of garnet + rutile + kyanite + corundum in the peak metamorphic stage of pelitic granulite indicates that it may underwent ultra-high-pressure metamorphism, and the acidic plagioclase exsolution of clinopyroxene in garnet pyroxenite also suggests that it may be retrograded eclogites, which indicates that the deeper Cathaysian block may have eclogite metamorphism. Analyses of LA-ICP-MS zircon U-Pb dating indicate that the metamorphic age of pelitic granulite is 233.5 Ma–subduction/collision followed by rapid exhumation and cooling events. The events may relate with the amalgamation of the Indochina BlockSouth China Block North China Block in the paleo-Tethyan domain.

Structural and tectonothermal evolution of the ultrahigh-temperature Bakhuis Granulite Belt,Guiana Shield,Surinam:Palaeoproterozoic to recent

We constrain the multistage tectonic evolution of the Palaeoproterozoic UHT metamorphic(P=0.9–1.0 GPa,T>1000℃,t=2088–2031 Ma)Bakhuis Granulite Belt(BGB)in Surinam on the Guiana Shield,using large-to small-scale structures,Al-in-hornblende thermobarometry and published fluid inclusion and zircon geochronological data.The BGB forms a narrow,NE–SW striking belt between two formerly connected,~E–W oriented granite-greenstone belts,formed between converging Amazonian and West African continental masses prior to collision and Transamazonian orogeny.Inherited detrital zircon in BGB metasediments conforms agewise to Birimian zircon of West Africa and suggests derivation from the subsequently subducted African passive margin.Ultrahigh-temperature metamorphism may have followed slab break-off and asthenospheric heat advection.Peak metamorphic structures result from layer-parallel shearing and folding,reflecting initial transtensional exhumation of the subducted African margin after slab break-off.A second HT event involves intrusion,at ca.0.49 GPa,of charnockites and metagabbros at 1993–1984 Ma and a layered anorthosite at 1980 Ma,after the BGB had already cooled to<400℃.The event is related to northward subduction under the greenstone belts,along a new active margin to their south.A pronounced syntaxial bend in the new margin points northward towards the BGB and is likely the result of indentation by an anticlinorial flexural bulge of the subducting plate.Tearing of the subducting oceanic plate along this bulge explains why the charnockites are restricted to the BGB.The BGB subsequently experienced doming under an extensional detachment exposed in its southwestern border zone.Exhumation was focused in the BGB as a result of the flexural bulge in the subducting plate and localised heating of the overriding plate by charnockite magmatism.The present,straight NE–SW long-side boundaries of the BGB are superimposed mylonite zones,overprinted by pseudotachylites,previously dated at ca.1200 Ma and 950 Ma,respectively.The 1200 Ma mylonites reflect transpressional popping-up of the BGB,caused by EW-directed intraplate principal compressive stresses from Grenvillian collision preserved under the eastern Andes.Further exhumation of the BGB involved the 950 Ma pseudotachylite decorated faulting,and Phanerozoic faulting along reactivated Meso-and Neoproterozoic lineaments.

Oxygen Fugacity and Water Activity during Thermal Peak and Retrogression of Granulites around the Sarvapuram Area, Karimnagar Granulite Terrane, Andhra Pradesh, India

The investigated area around Sarvapuram represents a part of the Karimnagar granulite terrane of the Eastern Dharwar Craton, India. Garnet–bearing gneiss is hosted as enclaves, pods within granite gneiss and charnockite. It is largely made up of garnet, orthopyroxene, cordierite, biotite, plagioclase, K–feldspar, sillimanite and quartz. The peak metamorphic stage is represented by the equilibrium mineral assemblage i.e. garnet, orthopyroxene, cordierite, biotite, plagioclase, sillimanite and quartz. Breakdown of the garnet as well as preservation of the orthopyroxene–cordierite symplectite, formation of cordierite with the consumption of the garnet + sillimanite + quartz represents the decompressional event. The thermobarometric calculations suggest a retrograde P–T path with a substantial decompression of c. 3.0 kbar. The water activity(XH2 O) conditions obtained with the win TWQ program for core and symplectite compositions from garnet–bearing gneiss are 0.07–0.14 and 0.11–0.16 respectively. The quantitative estimation of oxygen fugacity in garnet–bearing gneiss reveal log f O2 values ranging from-11.38 to-14.05. This high oxidation state could be one of the reasons that account for the absence of graphite in these rocks.

Thermal history of a Late Mesoproterozoic paired metamorphic belt(?)during Rodinia assembly:New insight from medium-pressure granulites from the Aravalli-Delhi Mobile Belt, Northwestern India

In this study, we investigate the possible record of a Late Mesoproterozoic paired metamorphic belt in the Aravalli-Delhi Mobile Belt(ADMB), NW India using a suite of supracrustal and metaigneous granulites from the Pilwa-Chinwali granulite terrain at the north-western margin of the ADMB. Using metamorphic reaction textures, mineral chemistry, metamorphic reaction history, geothermobarometric computations and electron microprobe dating of monazite in 5 samples of pelitic granulite, leptynite gneiss, enderbite and charnockite, we have deduced a medium-pressure granulite facies metamorphism(P between 4.9 and 6.8 kbar, T> 760-815℃) along a heating-cooling, counterclockwise P-T path between 1.09 and 1.01 Ga. When collated with published metamorphic and chronological constraints and geological settings of the adjoining crustal domains of the ADMB, these findings provide new insights into the developments of two tectonic domains of contrasting thermal gradients at ca. 1.0 Ga, consistent with metamorphic transformations in tectonically thickened middle-lower crustal sections during continental collision to continental subduction and in the root zones of spatially adjacent island arc, as part of the Rodinia supercontinent assembly event.

Anticlockwise P-T Path and Zircon U-Pb Dating of HP Mafic Granulites in Yushugou Granulite-Peridotite Complex, Southern Tianshan Mountains, China

The Yushugou HP granulite-peridotite complex is located at east of northern margin of southern Tianshan mountains,China,which consists of granulite unit and peridotite unit mainly.Because of the rare association

A Plate-Tectonic Model for the Evolution of the Daqingshan Granulite belt in Inner Mongolia

One of the most important events in the early geological evolutionary history of the Earthwas the wide occurrence of granulite belts at the end of the Archaean in the world, whichmeans a possible transformation of evolution mechanism of the crust. More and more geo-

The Metamorphism of High-Pressure Basic Granulite in Laixi District, East Shandong, China

A high pressure basic granulite ultramafics belt is found in the late Archaean gneisses of Laixi Laiyang Qixia district, east Shandong. This belt has previously been considered as another eclogite belt in Sulu ultra high pressure(UHP) terrain. The typical high P granulite is characterized by mineral assemblages of three generations formed in different metamorphic episode respectively. The mineral assemblage of first episode is Grt(core)+Cpx+Pl, that of the second episode is Grt(rim)+Cpx+Opx+Pl+Amp+Q+Mt and that of the third episode is Cpx+Pl+Amp+Q+Mt. In first assemblage, the garnet porphyroblast is rich in grossular and pyrope component, and the coexisting Cpx is Al rich. Using mineral thermobarometer and Berman’s (1991) TWQ program, the P T conditions of three episodes are established, i.e. T=840℃～860℃, P>1.4GPa for first episode; T=720℃～780℃,P=0.8～1.2GPa for second episode and T=600℃～800℃,P=0.5～0.7GPa for the third episode.Considering the reaction texture, mineral Chemistry and PT estmations, a clockwise PTt path can be constructed, which shows post peak isothermal decompression at first and followed by a process of pressure and temperature decreasing. The mineral wholerock Sm Nd isochron age of the granulite is 1752Ma, which indicates its last thermal event during early middle Proterozoic stage. Therefore, it is concluded that the high pressure granulite and ultramafics of this belt represents the lower continental curst of the North China Craton during early Precambrian without any relationship to tectonic process of the Sulu UHP terrain.

Multiple Episodes of Zircon Growth during Anatectic Metamorphism of Metasedimentary Rocks in Collisional Orogens:Constraints from Felsic Granulites in the Bohemian Massif

Zircon is a key accessary mineral for metamorphic geochronology and geochemical tracing,but it has been a challenge to interpret its complex chemical zoning and age record acquired during multiple episodes of anatectic metamorphism in collisional orogens.This is illustrated by a combined study of petrography,phase equilibrium modeling and metamorphic P-T-t determination for granulites from the Bohemian Massif in the Variscan Orogen.These rocks record multiple episodes of zircon growth during anatectic metamorphism.They started from the compressional heating for prograde metamorphism to high-pressure(HP)to ultrahigh-pressure(UHP)eclogite facies with low degrees of partial melting.Afterwards,they underwent a decompressional stage from UHP eclogite facies to HP granulite facies for dehydration melting.These were followed by a further decompressional stage either to kyanite granulite facies or to sillimanite granulite facies at ultrahigh-temperature(UHT)conditions.Episodes of zircon growth are linked to specific metamorphic conditions for peritectic reactions on the basis of zoning patterns,trace element signatures,index mineral inclusions in dated domains and textural relationships to coexisting minerals.The results indicate that relict zircon domains are preserved even at UHT granulite facies conditions.A few zircon domains in the kyanite granulite grew during the prograde to peak UHP metamorphism,possibly corresponding to consumption of biotite and plagioclase but growth of garnet.During the decompressional exhumation to the HP granulite-facies,relict or prograde zircon domains were mostly dissolved into anatectic melts produced by muscovite breakdown.Most zircon grains grew during this transition to the HP granulite-facies in the kyanite granulite and are chemically related to continuous growth of garnet,whereas abundant zircon grains grew subsequently at the UHT granulite facies in the sillimanite granulite and are chemically related to garnet breakdown reactions.Another peak of zircon growth occurred at the final crystallization of anatectic melts in the sillimanite granulite rather than in the kyanite granulite,and these zircon grains mostly show oscillatory zoning,low HREE+Y contents and significantly negative Eu anomalies.In terms of the inference for protolith nature,it appears that zircon in metasedimentary rocks can grow at a short timescale in different stages of anatectic metamorphism,and its dissolution and growth are mainly dictated by anatectic conditions and extent,the property of peritectic reactions,and the stability of Ti-rich minerals.