Early Oligocene anatexis in the Yardoi gneiss dome, southern Tibet and geological implications

The Yardoi gneiss dome is located to the easternmost of the North Himalayan Gneiss Dome (NHGD), southern Tibet. It consists of metapelite, garnet amphibolite, granite and leucogranite, and is a key subject to constrain the formation and tectonic evolution of NHGD. SHRIMP zircon U/Pb data on the leucogranite yield an age of 35.3±1.1 Ma, which is substantially older than that of the similar leucogranites to the west. Sr and Nd isotope systematics indicate that this leucogranite was derived from partial melting of the mixed garnet amphibolite and metapelite. Our data suggest that (1) during the early stage of Himalayan magmatism, amphibolite dehydration melting overwhelmed that of the metapelite; and (2) such a melting at middle-lower crust might be a major factor that initiated the movement along the Southern Tibetan Detachment System (STDS). Supported by National Natural Science Foundation of China (Grant No. 40673027), the Outlay Research Fund of Chinese Academy of Geological Sciences (Grant No. 20071120101125), and the Hundred Talent Program of Chinese Academy of Sciences     

内蒙古中部乌拉山-大青山地区富铝片麻岩年代学特征

内蒙古中部乌拉山岩群是一套变质程度为高角闪岩相-麻粒岩相的早前寒武纪高级变质岩系,出露于内蒙古中部。为划分乌拉山-大青山地区富铝片麻岩的原岩形成时代,通过对侵入乌拉山岩群黑云石榴斜长片麻岩的石英闪长质片麻岩和紫苏花岗质片麻岩变质深成体进行年代学研究,本次研究涉及的实验样品共6件,分别于内蒙古中部乌拉山-大青山地区片麻岩中和变质深成岩中各取3件。分别为矽线石榴黑云斜长片麻岩(TWB19)、黑云斜长片麻岩(TWB20)、含橄榄石方解石大理岩(TWB18)和紫苏花岗质片麻岩(TW7)、石英闪长质片麻岩(TWB6)和花岗闪长质片麻岩(D1227)。结果表明：紫苏花岗质片麻岩(TW7)的加权平均年龄为2462±13Ma,花岗闪长质片麻岩(D1227)加权平均年龄为2512±24Ma,由于后期构造事件对岩石的改造,锆石的实际年龄应更大一些。可见,乌拉山富铝片麻岩原岩形成年代早于2.5Ga。石英闪长质片麻岩(TWB6)的变质年龄为2.2Ga和1.9Ga,指示乌拉山-大青山地区遭受古元古代早期和晚期构造热事件叠加改造。综上所述,乌拉山-大青山地区富铝片麻岩最晚形成时代限定在2.5Ga。     

Episodic crustal anatexis and the formation of Paiku composite leucogranitic pluton in the Malashan Gneiss Dome, Southern Tibet

The Paiku composite leucogranitic pluton in the Malashan gneiss dome within the Tethyan Himalaya consists of tourmaline leucogranite, two-mica granite and garnet-bearing leucogranite. Zircon U-Pb dating yields that (1) tourmaline leucogranite formed at 28.2±0.5 Ma and its source rock experienced simultaneous metamorphism and anatexis at 33.6±0.6 Ma; (2) two-mica granite formed at 19.8±0.5 Ma; (3) both types of leucogranite contain inherited zircon grains with an age peak at ～480 Ma. These leucogranites show distinct geochemistry in major and trace elements as well as in Sr-Nd-Hf isotope compositions. As compared to the two-mica granites, the tourmaline ones have higher initial Sr and zircon Hf isotope compositions, indicating that they were derived from different source rocks combined with different melting reactions. Combined with available literature data, it is suggested that anatexis at ～35 Ma along the Himalayan orogenic belt might have triggered the initial movement of the Southern Tibetan Detachment System (STDS), and led to the tectonic transition from compressive shortening to extension. Such a tectonic transition could be a dominant factor that initiates large scale decompressional melting of fertile high-grade metapelites along the Himalayan orogenic belt. Crustal anatexis at ～28 Ma and ～20 Ma represent large-scale melting reactions associated with the movement of the STDS.     

A ∼2.5 Ga magmatic event at the northern margin of the Yangtze craton: Evidence from U-Pb dating and Hf isotope analysis of zircons from the Douling Complex in the South Qinling orogen

The poorly studied Douling Complex is a crystalline basement that developed in the Neoproterozoic-Paleozoic weakly metamorphosed to non-metamorphosed strata at the South Qinling tectonic belt. Five banded dioritic-granitic gneiss samples from the Douling Complex were chosen for LA-MC-ICPMS U-Pb zircon dating, which yielded protolith emplacement ages of 2469 ± 22 Ma, 2479 ± 12 Ma, 2497 ± 21 Ma, 2501 ± 17 Ma and 2509 ± 14 Ma, respectively. An important peak age of ～2.48 Ga was also obtained for a metasedimentary rock in the same region. These discoveries suggest the occurrence of magmatic activity of 2.51–2.47 Ga at the northern margin of the Yangtze craton. The age-corrected ? _Hf(t) values obtained from in situ zircon Hf isotopic analysis are mainly between ?5.5 and +0.3, and the two-stage zircon Hf model ages range from 3.30 to 2.95 Ga. Considering two important periods of ～3.3–3.2 Ga and ～2.95–2.90 Ga for the continental crustal growth in the Yangtze craton, we infer that the dioritic-granitic gneisses from the Douling Complex are the products of reworking of Paleo- to Mesoarchean crust at the northern margin of the Yangtze craton at ～2.5 Ga. In addition, metamorphic ages of 837 ± 8 Ma and 818 ± 10 Ma were obtained for zircon overgrowth rims from a dioritic gneiss and a metasedimentary rock, indicating that the main phase amphibolite facies metamorphism of the Doulng Complex occurred during the Neoproterozoic, although its geological meaning remains ambiguous.     

Zircon SHRIMP geochronology of the Xinkailing-Kele complex in the northwestern Lesser Xing＇an Range, and its geological implications

Located in the eastern portion of the Xing'an-Mongolian Orogenic Belt (XMOB), the Xinkailing-Kele complex has previously been considered to be Precambrian metamorphic rocks, mainly according to its relatively high metamorphic grade. Our filed observation, however, revealed that the complex is composed mainly of metamorphic rocks (Kele complex), tectono-schists ("Xinkailing Group"), and granitoids (Xinkailing granitic complex). Dating on these rocks using advanced SHRIMP zircon U-Pb technique indicates that: (1) Biotite-plagioclase gneiss from the Kele complex has a protolith age of 337±7 Ma (2σ) and a metamorphic age of 216±3 Ma (2σ); (2) the tectono-schist of the "Xinkailing Group" gave a magmatic age of 292±6 Ma (2σ), indicative of felsic volcanic protolith of the schist formed in late Paleozoic time; and (3) the Menluhedingzi and Lengchuan granites of the Xinkailing granitic complex were emplaced at 167±4 (2σ) and 164±4 Ma (2σ), respectively. These results suggest that the Xinkailing-Kele complex is not Precambrian metamorphic rocks and the so-called Precambrian "Nenji-ang Block" does essentially not exist. In combination with regional geological data, we propose that the Kele metamorphic complex is likely related to a collisional tectonism that took place in Triassic time, as indicted by its metamorphic age of 216±3 Ma. The Xinkailing granitic complex was em-placed along the collisional zone during Mid-Jurassic time, likely in a post-orogenic or anorogenic setting.     

Multi-stage evolution of gneiss from North Dabie： evidence from zircon U-Pb chronology

TTG gneiss is a common rock to outcrop in the northern part of the Dabie orogen, a few of which are closely associated with eclogites that experienced the Triassic ultrahigh pressure metamorphism. Although they were thermally metamorphosed by a large-scale magma activity in this region at the Early Cretaceous, it is unclear whether or not they are also affected by the Triassic metamorphism during continental subduction and exhumation. In order to resolve this issue, SHRIMP zircon U-Pb dating was carried out for the host gneiss of eclogites in North Dabie. The results show that cores from the gneiss have an age of 746~.31 Ma, consistent with the protolith ages of granitic gneisses in the Dabie orogen. Zircon overgrowing with different U and Th concentrations give concordant ages of 212~21 and 120~11 Ma, respectively. Th/U ratios of overgrown zircons are both lower than 0.1, suggesting a metamorphic genesis. The present resuits suggest that the gneiss in North Dabie has the similar protolith ages of Neoproterozoic to those granitic gneisses elsewhere in the Dabie orogen, and experienced not only the Triassic metamorphism but also the thermal metamorphism due to the Early Cretaceous magmatism. This provides an important insight into the geodynamic evolution of gneissic rocks in the Dabie orogen.     

Zircon U-Pb SHRIMP dating of the Yematan batholith in Dulan,North Qaidam,NW China

The Yematan batholith crops out over 120 km^2 in the North Qaidam ultrahigh pressure (UHP) metamorphic belt. It consists of granodiorite, monzogranite and biotite granite and forms an irregular intrusion into Neoproterozoic gneiss that has undergone Caledonian UHP metamorphism. Zircons from the Yematan granodiorite yield a SHRIMP U-Pb age of 397 3 Ma. These granitic rocks have geochemical characteristics intermediate between I- and S-type granites, and are post-collisional. We suggest that the Yematan granitic rocks were formed during the last exhumation event of the North Qaidam UHP belt.     

Process and mechanism of mountain-root removal of the Dabie Orogen—Constraints from geochronology and geochemistry of post-collisional igneous rocks

Systematical studies of post-collisional igneous rocks in the Dabie orogen suggest that the thickened mafic lower crust of the oro- gen was partially melted to form low-Mg# adakitic rocks at 143-131 Ma. Delamination and foundering of the thickened mafic lower crust occurred at 130 Ma, which caused the mantle upwelling and following mafic and granitic magmatic intrusions. Mig- matite in the North Dabie zone, coeval with the formation of low-Mg# adakitic intrusions in the Dabie orogen, was formed by partial melting of exhumed ultrahigh-pressure metamorphic rocks at middle crustal level. This paper argues that the partial melting of thickened lower and middle crust before mountain-root collapse needs lithospheric thinning. Based on the geothermal gradient of 6.6~C/km for lithospheric mantle and initial partial melting temperature of ~1000~C for the lower mafic crust, it can be estimated that the thickness of lithospheric mantle beneath thickened lower crust has been thinned to 〈45 km when the thickened lower crust was melting. Thus, a two-stage model for mountain-root removal is proposed. First, the lithospheric mantle keel was partially removal by mantle convection at 145 Ma. Loss of the lower lithosphere would increase heat flow into the base of the crust and would cause middle-lower crustal melting. Second, partial melting of the thickened lower crust has weakened the lower crust and increased its gravity instability, thus triggering delamination and foundering of the thickened mafic lower crust or mountain-root collapse. Therefore, convective removal and delamination of the thickened lower crust as two mechanisms of lithospheric thin- ning are related to causality.     

Zircon isotopic ages from magnetite quartzites of the Jianping metamorphic complex, western Liaoning Province

Using the zircon Pb evaporation method and high precise ion microprobe analyses, zircon isotopic ages in supracrustal magnetite quartzites from Jianping metamorphic complex have been obtained. The results show that the deposition of the supracrustal rocks occurred around 2 552–2 520 Ma and the peak of granulite facies metamorphism reached at about 2 487 Ma; about (1 806±16) Ma, i.e. Mid-Proterozoic, the other possible metamorphic event with relatively low intensity happened in the study area. It is speculated that a likely tectonic setting where the Jianping metamorphic complex formed is an active continental margin that is involved in continental collision and crustal thickening shortly after its formation.     

LA-ICP-MS zircon U-Pb dating for high-pressure basic granulite from North Qinling and its geological significance

Inrecentyears,discoveriesofhightoultrahighpressuremetamorphicrocksatthenorthandsouthsidesoftheQinlingGroupinthenorthernpartoftheQinlingMountains(hereafterNorthQinling)haveattractedfocusattentionofgeologistsworldwide.Thenorthhigh-pressure(HP)metamorphicbelt,distributedintheareafromGuanpotoShuanghuaishunorthwardtoShizipin,LushCountyinHenanProvince,consistsmainlyofeclogiteoutcroppedaslenticularmassesofdifferentsizesinthegneissesoftheQinlingGroupclosetothesouthsideofZhuyangguan-Xiaguanfault…     

Structures, kinematics, thermochronology and tectonic evolution of the Ramba gneiss dome in the northern Himalaya

The Ramba gneiss dome, one of the north Himalayan gneiss domes, is composed of three tectono-lithologic units separated by an upper and a lower detachment fault. Low-grade metamorphic Tethyan Himalayan sedimentary sequence formed the upper unit above the brittle upper detachment fault. Mylonitic gneiss and a leucogranite pluton made up the lower unit beneath the ductile lower detachment fault. Mylonitic middle-grade garnet-, staurolite- and andalusite-schist constituted the middle unit between the two faults, which may be that the basal part of the upper unit experienced detachment shear. The Ramba dome underwent three episodes of deformation in its tectonic evolution. The first episode was a top-down-to-north-northwest sliding possibly related to the activity of the south Tibetan detachment system （STDS）. The second episode was the dominant deformation related to a east west extension, which resulted in a unique top-down-to-east kinematics and the major tectonic features of the dome. The third episode was a collapse sliding toward the outsides of the dome. The Ramba gneiss dome is possibly a result of the east-west extension and magmatic diapir. The lower detachment fault is probably the main detachment fault separating the sedimentary sequence from the crystalline basement during the eas-west extension in the dominant deformation episode. The diapir of the leucogranite pluton formed the doming shape of the Ramba gneiss dome. This pluton intruded in the core of the dome in a late stage of the dominant deformation, and its Ar-Ar cooling ages are about 6 Myr. This indicates that the dominant deformation of the dome happened at the same time of the east west extension represented by the nort-south trending rifts throughout the northern Himalaya and southern Tibet. Therefore, the formation of the Ramba gneiss dome should be related to this east west extension.     

Reinterpretation of metamorphic age of the Hengshan Complex, North China Craton

Hengshan granulite facies terrane consists of tonalite-trondhjemite-granodiorite(TTG)gneisses and minor high-pressure mafic granulite blocks.LA-ICP-MS zircon dating for two TTG gneiss samples indicates metamorphic ages of 1916.7±9.9 Ma and1850–1930 Ma,and magmatic protolith age of ca.2.5 Ga,with similar HREE-rich patterns.Phase equilibria modelling in ZrO2-bearing system reveals that zircon abundance varies inversely with melt abundance in suprasolidus metamorphism,zircon growth occurs with melt crystallization during cooling,and thus,the newly grown zircon can only record the age of retrograde metamorphism.Consequently,we suggest that the Hengshan granulite facies terrane experienced slowly uplifting and cooling during 1.85–1.93 Ga in an extensional setting under middle-crust,while the collision orogeny corresponding to peak stage of high-pressure granulite may have happened much earlier.     

Experimental study on dehydration melting of natural biotite-plagioclase gneiss from High Himalayas and implications for Himalayan crust anatexis

Here we present the results of dehydration melting, melt morphology and fluid migration based on the dehydration melting experiments on natural biotite-plagioclase gneiss performed at the pressure of 1.0—1.4 GPa, and at the temperature of 770—1028℃. Experimental results demonstrate that: (ⅰ) most of melt tends to be distributed along mineral boundaries forming “melt film” even the amount of melt is less than 5 vol%; melt connectivity is controlled not only by melt topology but also by melt fraction; (ⅱ) dehydration melting involves a series of subprocesses including subsolidus dehydration reaction, fluid migration, vapor-present melting and vapor-absent melting; (ⅲ) experiments produce peraluminous granitic melt whose composition is similar to that of High Himalayan leucogranites (HHLG) and the residual phase assemblage is Pl+Qz+ Gat+Bio+Opx± Cpx+Ilm/Rut± Kfs and can be comparable with granulites observed in Himalayas. The experiments provide the evidence that biotite-plagioclase gneiss is one of source rocks of HHLG and dehydration melting is an important way to form HHLG and the granulites. Additionally, experimental results provide constraints on determining the P-T conditions of Himalayan crustal anatexis.     

Garnet Sm-Nd and U-Pb systems: A case study of a granulite from the European Variscan belt

This study presents zircon and garnet ages of a mafic granulite from the high-grade Variscan basement of the Black Forest, Germany and discuss isotope closure temperature of garnet Sm-Nd and U-Pb systems. Zircon grains yield 207Pb/206Pb ages between ～340 and ～414 Ma by the U-Pb and evaporation methods. In contract, garnet dating gives Sm-Nd and Pb-Pb isochron ages of (398±3) Ma and (411±14) Ma, respectively, which are older than most of zircon ages. These data imply that most of zircons lost radiogenic Pb, probably due to metamictization or recrystallisation during the granulite-facies metamorphism (～800℃) at ～340 Ma. Garnet Sm-Nd and U-Pb systems preserve chronological information of pro-grade metamorphism, probably profiting from a fluid-absence metamorphic environment. These results demonstrate that garnet mineral can be a better candidate than zircon mineral to date high-grade metamorphism by the U-Pb and Sm-Nd methods in some cases.     

Granitic magmatism related to early Paleozoic continental collision in North Qinling

Zircon U-Pb dating of early Paleozoic granitoids in North Qinling yields three age peaks of ~500, -452 and -420 Ma. They can be temporally correlated with high-pressure to ultrahigh-pressure metamorphism at ca. 500 Ma, retrograde granulite-facies meta- morphisms at ca. 450 Ma and amphibolite-facies metamorphism at ca. 420 Ma, respectively. The first episode of granitic magma- tism is considered to have resulted from continental collision, whereas the second and third episodes of magmatism are attributed to crustal uplifting. Combined with the regional geological setting and new results from high-pressure and ultrahigh-pressure metamorphic rocks, the ca. 500 Ma magmatism is interpreted as the result of partial melting of sedimentary rocks in accretionary wedge between the south Qinling microcontinent and the north Qinling belt including the southern margin of the North China Craton. The ca. 450 Ma intensive magmatism is ascribed to dehydration melting of deeply subducted continental crust at thick- ened conditions in response to slab breakoff, and the final magmatism in ca. 420 Ma is interpreted as the product of partial melt- ing during the tectonic transition from contraction to extension.     

Discovery of Late Paleozoic retrograded eclogites from the middle part of the northern margin of North China Craton

The northern margin of the North China Craton (NCC), located between the Paleo-Asian Ocean tectonic region on the north and the NCC on the south, is a key region for studying the tectonic evolution of NCC. A Pre-cambrian retrograded eclogite (2500 Ma or 1800 Ma) was reported in Baimashi near Hengshan Mountain in the NCC, which is characterized by the vermicular symplec-tite of diopside and plagioclase with absence of ompha-cite[1,2]. In Hongqiyingzi Group from the middle part of the …     

Triassic U-Pb age for zircon from granites in the Tonghua area and its response to the Dabie-Sulu ultrahigh-pressure collisional orogenesis

Single-grain zircon U-Pb dating was carried out to constrain the emplacement timing of granitic plutons at Chaxinzi, Xiaoweishahe and Longtou in the Tonghua area, south of Jilin Province. The results show that these plutons formed in the Triassic with ages of 203—217 Ma. Geological and geochemical characteristics indicate that the plutons are composed of quartz diorite and granite. The former was derived from partial melting of mafic lower crust, whereas the latter originated from thickened crust with garnet as the residue in the source. It appears that protoliths of these two types of granitits are different although they have the same emplacement age. Considering that these plutons are petrologically different from the coeval granites in the Xingmeng (Xing‘an-Mongolian) to Jihei (Jilin-Heilongjiang) orogenic belt in the north, it is suggested that their formation was related to the Dabie-Sulu ultrahigh-pressure collisional orogenesis since their ages are only 10—20 Ma younger than timing of the ultrahigh-pressure metamorphism, but comparable to that of the first rapid exhumation of the ultra-high-pressure metamorphic rocks and the emplacement of the post-collisional granites.     

Formation history and protolith characteristics of granulite facies metamorphic rock in Central Cathaysia deduced from U-Pb and Lu-Hf isotopic studies of single zircon grains

The petrochemical as well as zircon U-Pb and Lu-Hf isotopic studies of granulite facies metamorphic rock from the Tao＇xi Group in eastern Nanling Range, Central Cathaysia indicate that its protolith is the sedimentary rock with low maturation index. The clastic materials are mostly from middle Neoproterozoic （-736 Ma） granitoid rocks with minor Neoarchaean and Paleoproterozoic rocks. The timing of this Neoproterozoic magmatism is in agreement with the second period of magmatism widespread surrounding the Yangtze Block. Hf isotopic data indicate that the Neoproterozoic granitoids resulted from the recycled Paleoproterozoic mantle-derived crustal materials. The sedimentary rock was deposited in Late Neoproterozoic Era, and carried into low crust in Early Paleozoic. The partial melting of the meta-sedimentary rock took place at about 480 Ma and subsequently granulite facies metamorphism occurred at ca. 443 Ma. The zircons forming during this time interval （Early Paleozoic） show large Hf isotope variations, and their ZHf（t） values increase from -13.2 to ＋2.36 with decreasing age, suggesting the injection of mantle-derived materials during partial melting and metamorphism processes in the Early Paleozoic. Calculation results show that this metamorphic rock, if evolved to Mesozoic, has similar isotopic composition to the nearby Mesozoic high Si peraluminous granites, implying that this kind of granulite facies metamorphic rock is probably the source material of some Mesozoic peraluminous granitoids in eastern Nanling Range.     

Ore-forming event and geodynamic setting of molybdenum deposit at Wenquan in Gansu Province, Western Qinling

The Wenquan molybdenum deposit is associated with a Triassic granite in this area. The Wenquan granite is enriched in LILE and LREE, poor in HFSE, and has significantly higher contents of alkali （K2O＋Na2O） and Sr, Ba than those of the island arc volcanic rocks. These geochemical characteristics are similar to post-collisional granites in high K calc-alkaline series. Studies of major elements, trace elements, REEs and chronology of the Wenquan pluton show that, in the geodynamic transition stage of continent-continent convergence to extension, the partial melting of the enriched lithospheric mantle generated the basaltic magma and triggered the partial melting of the thickened lower crust which produceded the acidic magma, and the Wenquan pluton was formed by mixing of the two magmas. Molybdenite Re-Os isotopic dating gave Os model ages of 212.7±2.6 Ma to 215.1±2.6 Ma with a weighted mean of 214.1±1.1 Ma, and an Re-Os isochron age of 214.4±7.1 Ma. These ages are close to K-Ar ages （223 to 226 Ma） and a SHRIMP zircon U-Pb age （223±7 Ma） for the Wenquan granite within the error range, but relatively younger. This implies that the Mo mineralization occurred in a late stage of the magmatic intrusion, and the metallogenesis took place in the transition stage from syn-collision to post-collision in the tectonic setting of the Qinling Orogenic Belt （QOB） after continental collision between the North China Block （NCB） and the South China Block （SCB）. This process is also corresponding to the geological events of metamorphism and deformation in South Qinling, closure of the Mian-Lue oceanic basin, and exhumation of the Dabie-Sulu ultrahigh-pressure metamorphic rocks. The large-scale continent-continent collision between NCB and SCB in the middle Triassic triggered significant crustal thickening and exhumation of subducted slab. In the late Triassic, the tectonic setting was transformed to the transition stage from collision to extension. Materials from the asthenospheric mantle would ascend into the root of the lower crust, which could induce partial melting of the lower crust and generate Mo-enriched granitic magma. The ore-forming elements enriched in the fluid derived from the condensation and fraction of the magma resulted in the Mo mineralization. The Mo deposits in the QOB are mainly formed in two episodes, namely 220± Ma and 140± Ma. The two episodes of metallogenesis were developed in the tectonic transition settings from compression to extension, but they were in the different stages of the tectonic evolution. The occurrence of the Wenquan Mo-bearing pluton indicates that the Triassic tectonic-magmatic belt of Western Qinling is another favorable region for Mo mineralization in the QOB. Therefore, it is significant to pay more attention to evaluation of the ore-forming potentiality in the Triassic granites in Western Qinling.     

Genesis of granulite in Himalayan lower crust: Evidence from experimental study at high temperature and high pressure

Here we present an insight into the genesis of Himalayan granulitic lower crust based on the experimental studies on the dehydration melting of natural biotite-plagioclase gneiss performed at the temperatures of 770-980℃ and the pressures of 1.0-1.4 GPa. The experiments produce peraluminous granitic melt and residual phase assemblage (Pl+Qz+Gat+Bio+Opx±Cpx+Ilm/Rut±Kfs). The residual mineral assemblage is similar to those of granu-lites observed at the eastern and western Himalayan syntax-ises, and the chemical compositions of characteristic minerals-garnet and pyroxene in the residual phase and the granu-lite are identical. Additionally, the modeled wave velocities of the residual phase assemblage are comparable well with those of the top part of lower crust beneath Himalayas. Hence, we suggest that (1) the top part of lower crust beneath Himalayas is probably made up of garnet-bearing intermediate granulite; (2) the formations of granulite and leucogranites in Himalayas are interrelated as the results of crustal anatexis; and (3) dehydration melting of bio-tite-plagioclase gneiss is an important process to form granulitic lower crust, to reconstitute and adjust the crustal texture. Moreover, experimental results can provide constraints on determining the P-T conditions of Himalayan crustal anatexis.