DSpace at VNU: Metamorphic evolution of pelitic–semipelitic granulites in the Kon Tum massif (south-central Vietnam)

DSpace at VNU: Metamorphic evolution of pelitic–semipelitic granulites in the Kon Tum massif (south-central Vietnam) tài...

Journal of Geodynamics 69 (2013) 148–164 Contents lists available at ScienceDirect Journal of Geodynamics journal homepage: http://www.elsevier.com/locate/jog Metamorphic evolution of pelitic–semipelitic granulites in the Kon Tum massif (south-central Vietnam) Vu Van Tích a,∗ , Andrey Leyreloup b , Henry Maluski b , Claude Lepvrier c , Chinh-hua Lo d , Nguye˜ˆ n V Vuo ng a a VNU-Hanoi University of Science, 334-Nguyen Trai Str, Hanoi, Viet Nam Laboratoire de Géoscience, Université Montpellier 2, Montpellier, France c Laboratoire de Tectonique, Université Pierre et Marie Curie, Paris, France d Department of Geology, National Taiwan University, Taipei, Taiwan b a r t i c l e i n f o Article history: Received 12 August 2010 Received in revised form 29 March 2012 Accepted 30 March 2012 Available online 11 April 2012 Keywords: Kon Tum massif Granulite Metapelite Indosinian Vietnam a b s t r a c t Pelitic and semipelitic anatectic granulites form one of the major lithological units in Kan Nack complex of the Kon Tum massif (in south-central Vietnam), which comprises HT metamorphic and magmatic rocks including granulites and charnockites is classically regarded as the older part of the Gondwanaderived Indosinia terrain Metamorphic evolution study of pelitic granulite, the most abundant among granulites exposed in this massif, facilitates to understand that tectonic setting take place during the Indosinian time The paragenetic assemblages, mineral chemistry, thermobarometry and P–T evolution path of pelitic–semipelitic granulites from Kon Tum massif has been studied in detail Petrographic feature demonstrates that the pelitic granulite experienced prograde history, from pregranulitic conditions in the amphibolite facies up to the peak granulitic assemblages Successive prograde reactions led to the temperature-climax giving rise to assemblages with cordierite-hercynite and cordierite-hercynite-Kfeldspar Then, as attested by the mineralogic association occurring in cordieritic coronas, these rocks have been affected by retrograde conditions coeval with a decrease of the pressure Thermobarometic results show that the highest temperature obtained by ksp/pl thermometry is 850 ◦ C and the highest pressure obtained by GASP (Garnet Alumino-Silicate Plagioclase) is 7.8 kbar The obtained clockwise P–T evolution path involving heating decompression, then nearly isothermal decompression and nearly isobar cooling conditions shows that high temperature–low pressure metamorphism of the studied pelitic anatectic granulites of Kan Nack complex occurred possibly in extensional setting during the Indosinian orogeny of 260–240 Ma in age © 2012 Elsevier Ltd All rights reserved Introduction The Indosinian orogeny in late Permian and Triassic times (Fromaget, 1941) is the expression of the collision of different Gondwana-derived continental terrains (Indosinia, Sibumasu, and South China), after narrowing and suturing of different branches of the Paleotethys (Metcalfe, 1996; Lepvrier et al., 2004) The southcentral area of Vietnam territory which corresponds to the Kon Tum massif (Fig 1A) exposes widespread high temperature crystalline rocks subdivided into four lithological units: granulitic facies Kan Nack complex in the south-east; amphibolitic facies Ngoc Linh complex in central; greenschists-amphibolite facies Kham Duc complex in the north and – greeschists-amphibolite Sa Thay (Dien Binh) complex in the west, which is commonly regarded as an old and ∗ Corresponding author Tel.: +84 35 58 70 60; fax: +84 38 58 30 61 E-mail address: tichvv@vnu.edu.vn (V.V Tích) 0264-3707/$ – see front matter © 2012 Elsevier Ltd All rights reserved http://dx.doi.org/10.1016/j.jog.2012.03.013 stable Precambrian basement (Phan Cu Tien et al., 1989) Because of the occurrence of high-temperature metasedimentary and igneous series comprising granulites and charnockites, this massif has classically been interpreted as a fragment of Gondwana, equivalent in age to the same facies rocks which are exposed in southern India and Antarctica (Katz, 1993) However, recent isotopic data show that the Kon Tum basement was affected by Permo-Triasic tectonometamorphic event (Tran Ngoc Nam et al., 2001; Nagy et al., 2001; Osanai et al., 2001; Maluski et al., 2005) There is now a broad recognition of the variety of P–T paths and tectonic settings to be found in granulite-facies terrains It was firstly assumed that granulitic rocks in orogenic belts typically experienced a crustal thickening (England and Richardson, 1977) Some models were proposed to account for type of retrograde path such as: metamorphism in extensional terrains (Sandiford and Powell, 1986) or in terrains heated by the addition of voluminous magmas (Bohlen, 1987) When parts of the prograde history (isobaric heating) could be detected, it suggests that magmatic V.V Tích et al / Journal of Geodynamics 69 (2013) 148–164 149 Fig (A) Location of the Kon Tum massif; (B) geological sketch map of the Kon Tum Massif and more detail of the Kan Nack complex (modified after Phan Cu Tien et al., 1989); (C) folliation data from the Kan Nack complex (along the Song Ba and the Song Bien reiver); (D) Interpretative section of the Kan Nack complex [1 granulites; gneiss, micaschists (the Ngoc Linh Complex: Metamorphic cover of the Kan Nack Complex); Paleozoic sediment; charnockites; Undeformed granites (Late Triassic and Cretaceous); Cenozoic basalts; Mesozoic sediments; quaternary sediments], Vn811 sample location accretion had played an important role in heat advection (Sandiford and Powell, 1986) Previous studies have given an idea of the global evolution of the area, but the diversity in protolith of granulites from different places obtained by previous works (Osanai et al., 2004) show that the thermo-tectonic setting of the Kon Tum massif is more complicated in detail Moreover, the large exposure of pelitic and semipelitic anatectic granulites (granulite leucosomes) in the Kon Tum basement which is important to understand tectonometamorphic setting, which has not been studied in detail The question therefore has to be asked, is the metamorphic P–T path of metapelitic granulitic leucosomes observed in the Kan Nack complex a single isothermal decompression and decompression cooling path or does it reflect a prograde (decompression heating) and isothermal decompression? So, detailed petrogenetic data are needed to constrain tectono-metamorphic evolution of this area In the this paper, we present here detailed petrography, mineral assemblage, and mineral chemistry of the Kan Nack pelitic granulites in order to understand the metamorphic history through reaction textures observed combining with P–T trajectory and thermobarometric calculations This data will be interpreted in the light of previous works (geochronology data) in order to discuss more about the thermo-tectonic evolution of the Kon Tum massif and its role during the Indosinian orogenic evolution Geological setting of the Kon Tum massif and the Kan Nack complex The studied area (Kon Tum massif) is located in south-central Vietnam (Fig 1A) The Kon Tum massif exposes a large scale of crystalline rocks It consists of mainly metasediments and orthogneisses, which were metamorphosed in amphibolitic and granulitic facies (Phan Cu Tien et al., 1989) This metamorphic basement is covered from place to place by Paleozoic-Mesozoic sediments or even directly by Neogene to Quaternary lava flows (Lee et al., 1998), and intruded by undeformed Jurassic-Triassic 150 V.V Tích et al / Journal of Geodynamics 69 (2013) 148–164 granites By contrast with the Truong Son Belt in the northern part of the Kon Tum massif, the Paleozoic sediments are nearly absent in the Kon Tum massif Based on metamorphic grade (Phan Cu Tien et al., 1989), Kon Tum massif has been subdivided into different complexes such as the Kan Nack complex composed essentially of granulitic and charnockitic rocks; the Ngoc Linh complex containing lower-grade metamorphic rocks in amphibolitic facies; the Sa Thay complex containing metapelitic and magmatic gneissic rocks, now so called Dien Binh unit (Maluski et al., 2005) and Kham Duc amphibolite facies complex (kyanite rocks) which was a transition zone between the Truong Son belt and the Kon Tum massif Structurally, the Kon Tum massif (Fig 1B) is essentially affected by two shear zone systems The western part of the Kon Tum Massif is bounded by a major N-S fault, as inferred by typical geomorphologic features, which can be followed over at least 200 km, running from Phuoc Son along the Po Ko river, and named “Po Ko fault zone” (Fig 1B) At the latitude of Dak To, the Po Ko fault swings eastwards and splays in different branches towards the Sa Thay valley and towards the Kon Tum basin and probably extends more to the South beneath the Pleiku plateau-basalts reaching the course of Da Rang river The kinematic criterias observed on mylonites along this fault zone indicate a sinitral ductile fault This so called Po Ko fault coincides with the boundary of two distinct and contrasted petrologic domains in the Kon Tum basement which are: To the East of the fault are exposed recently discovered charnockitic and granulitic rocks which constitute the westernmost occurrence of this material To the West, the exposed rocks are represented by the Dien Binh unit (Fig 1B), which is tectonically a different unit, mainly consisting in less deformed and non-granulitic metaigneous rocks with older than 250 Ma (Vu Van Tich, 2004) Mafic and ultramafic rocks assemblages of ophiolitic affinities are tectonically enclosed as elongated lenses and sheared bodies within the Po Ko fault zone Assemblages of ophiolitic affinities are present along this fault zone, which was considered as a paleosuture (Tran Van Tri, 1986) and resulting in a sinistral oblique subduction of Kon Tum micro-continent beneath to Kho Rat micro-continent (Lepvrier et al., 2004) In the northern part, the Kon Tum massif was affected by a series of the E–W high temperature deformed shear zones of Tra Bong – Phuoc Son (Kham Duc), progressively bend northwestwards to connect with the Po Ko Fault (Fig 1B) which forms the transition with the Truong Son belt Along this fault zone, rocks are highly deformed in ultramylonite facies where fibrous sillimanite dominates Kinematic criteria observed along this fault zone shows a dextral movement with a 60–70◦ dipping foliation to the south Ngoc Linh complex is limited by two these fault zones to the west and the north Rock of this complex are principally in biotite-hornblende gneisses, amphibolites, biotite-fibrous sillimanite-garnet bearing schists and graphite schists Along the cross-section from Kon Tum city to Song Re River, through Konplong, these rocks form a wide antiform which exhibits normal shear movements on both flanks, while a large granitic undeformed body occupies the core of the structure (Maluski et al., 2005) The Kan Nack complex is situated in central-eastern part of the Kon Tum block, separated with the Ngoc Linh complex by two main shear zones mentioned above Differing from the Ngoc Linh complex in metamorphic grade, the Kan Nack complex presents a basement with mainly anatectic granulitic rocks Geological maps of Vietnam show various names (Kon Cot, Xa Lam Co, Dak Ko and Kim Son unit) which identify the different stratigraphic units of the Kan Nack complex But this terminology generally refers to local toponymy and many names correspond in fact to the same petrologic units To clarify and simplify this situation, many of this local formations have been grouped, taking only into account their mineral assemblages and major petrological characteristics, whatever their degree of deformation and their geographic location Nevertheless, we have maintained usual terminology, when justified We observed along the upper course of Song Ba River (Fig 1B), this basement exposed by Al-rich metapelites, quartzites and marbles Mafic granulites, probably UHT granulites, although moderately deformed, are presented as lenses of anatectic pellitic granulites Structurally, they present low to moderate dippingfoliation, locally mylonitic and form gentle dome structures (Fig 1C, D) Whole of this basement is intruded by charnockitic rocks Charnockitic bodies, represented essentially by enderbites and locally norites, occur in the core of this structure (Fig 1D) Near Kan Nack village, inclusions of foliated granulites within the charnockites have been similarly observed (Fig 2) The Kan Nack complex is considered to be surrounded by a gneissic and schistosed material, forming the amphibolite facies Ngoc Linh Complex (Phan Cu Tien et al., 1989) The limit between this two complex is sometimes in faulted contact (Fig 1) Available geochronologic data show that the Kon Tum basement was affected at least by three main tectono-metamorphic events The oldest event occurred around of 1400 Ma, evidenced by age on core of zircon from pelitic granulite dated by Shrimps method (Tran Ngoc Nam et al., 2001) This result is explained as age from Proterozoic rocks in the Kon Tum massif crust corroborated by TMD from Sm/Nd data of granulite and charnockite in the Kan Nack complex The middle tectono-metamorphic event took place at around of 400–670 Ma This event is evidenced by some ages of 439 and 451 Ma is obtained from amphibolitic gneiss and orthogneiss from Dien Binh unit (Fig 1B) dated respectively by U–Pb and 40 Ar–39 Ar method (Nagy et al., 2001) A SRHIMP result with 401–418 Ma was obtained from orthogneiss in northern part of the Tra Bong (Fig 1B) shear zone (Carter et al., 2001) Some recent data obtained by different methods give similar results: a 678 Ma Sm–Nd age for remaining amphibolite from Kan Nack complex (Nakano et al., 2003); 479 Ma on monazite of the UHT granulite (small boudins of mafic granulite in pelitic basement) obtained by U–Th–Pb CHIME (Osanai et al., 2001); 405–403 Ma on biotites of granulite relic in a polymetamorphic green-schists, from the eastern part of the Kan Nack complex, obtained by 40 Ar–39 Ar method (Maluski et al., 2005) The third event took place during PermianTriassic time and marks the Indosinian orogeny, named for first time by French geologist (Fromaget, 1941), and expressed as a collision between different Gondwanian blocks (Lepvrier et al., 2004) This event was recorded by radiometric multimethods on different rocks not only in the Kon Tum massif but also in the Truong Son belt (Lepvrier et al., 1997; Lo et al., 1999; Maluski et al., 2005), on Hainan island (south China), and also in the south China block as noted in Carter et al (2001) The first evidence for this event in Kon Tum massif is an age of 235–246 Ma obtained by 40 Ar–39 Ar method on biotie from different metapelitic granulites in the Kan Nack complex (Maluski et al., 2005) These ages are confirmed by SHRIMP method, equivalent to peak metamorphic age of 254 Ma The same result (242, 250 and 238 Ma) has been obtained by the U–Th–Pb CHIME method for ultrahigh temperature granulite in the Kan Nack complex (Osanai et al., 2001) All these ages for granulites correlates well with emplacement age of the charnockitic intrusion at 251 Ma on five concordant zircon of the same rock (Nagy et al., 2001) and 258.5 Ma by the SHRIMP technique (Carter et al., 2001) Petrography, mineral chemistry and P–T path of pelitic granulites Petrological data were obtained after a detailed study under microscope and an extensive study with Camebax-50 EPMA at University of Montpellier II in France The rock type, sample location and mineral assemblage of each sample are presented in Table Representative electronic microprobe analyses of the mineralogical phases are given in weight% and cations per formula units, where V.V Tích et al / Journal of Geodynamics 69 (2013) 148–164 151 Fig Field observation photos in the Kan Nack complex from the Kon Tum massif: (A) contact granulite (dark and banded) and enderbitic charnockite (white color), (B) banded pelitic granulites molar fractions are also given (Table 2) Some particularities of studied minerals are discussed in the text All mineral abbreviations in the table; figure and the text are of Powell and Holland (2001) 3.1 Petrography We have observed granulites along the Song Bien brook, south of Hoai An town and along the Song Ba River (Fig 1B) They constitute the basement of the Kan Nak complex Originally, the protolith of granulites was constituted by sedimentary Al-rich series They contained pelites, semipelites, sandstones and Al-quartzites Calcareous and dolomitic sediments were intercalated Now, all these sediments are found as high-temperature metamorphic rocks, in the granulite facies, giving rise to khondalitic and kinzigitic banded anatectic gneisses (Fig 2B), granulitic metaquartzites for the more siliceous protoliths, and forsterite-humite calc-schists for the scarce calcareous-dolomitic ones In the field as in hand specimen, these high-grade metapelitic rocks show very intense layering and banding This layering is partly compositional, anatectic and tectonic The dark layers rich in garnet, cordierite, biotite and prismatic sillimanite represent the gneissic paleosomes or the residual melanosomes often as boudins wrapped by the regional foliation The white light layers represent quartzo-feldspathic leucosomes (anatectic peak liquid) These two kinds of layers are always parallel with the foliation From the point of view, these granulites are true metatexites The diatecxite stage of fusion has not been reached However, the very local intrusion of charnockite s.l magmatic liquid, cross-cutting the banded granulite foliation is even confusing as it looks like as evaluated diatexite (Fig 2) or even agmatite The granulite layering is also compositional since quarzitic or semi-pelitic layers (sometime zincian-poor or zincian-rich equilibrium), khondalitic quartz, K-feldspar layers, kinzigitic plagioclase rich, quartz poor layers coexist parallel in the same outcrops The observation of associated calcarous dolomitic deformed pods or layer forsterite-humit, calc-schist and marbles strongly supports this idea At last, all this high-grade rocks exhibit a huge tectonic banding They are strongly deformed in ductile conditions They are intensively foliated and lineated This is demonstrated by a strong stretching lineation in the main mylonitic shear zones, revealed by elongated prismatic sillimanite, platen quartz ribbons and oval garnets (Fig 3) Under the microscope, the mineralogies of all these layers is different according to the bulk-rock compositions of their protolite giving rise to quartz, acidic plagioclase, K-feldspar (mesoperthitic or not), biotite, and sometimes almandine-pyrope garnet and sillimanite granulitic leucosomes (Figs and 5) Anatectic conditions are reached within the stable biotite/quartz and garnet/K-feldspar/sillimanite/Zn–Fe rich spinel stability fields Quartz, K-feldspar, acidic plagioclase, Ti–Mg rich-biotites, Fe–Mg garnet, Mg rich-cordierites, prismatic sillimanite, Fe–Mg–Zn spinels are the main granulitic phases Graphite, Mg-ilmenite, Fe-sulphides, apatite and zircon are the main accessory minerals Magnetite and Ti-magnetite are rare and always altered in hydrated-hematite (martite) Zircon presents sometimes overgrowths When present, rutile has only been observed in the most altered granulites samples Yellow monazite and perhaps Table Mineral assemblage observed in some metasedimentary granulitic rocks in Kan Nack complex Sample GPS position Rock type Mineralogy Vn354, 355 Vn356 Vn373 Vn379 Vn413 Vn414 Vn415 Vn514 Vn515 Vn803 Vn362 Vn363 Vn805 Vn811 14◦ 18 04 14◦ 18 04 14◦ 15 15 14◦ 23 06 14◦ 18 04 14◦ 18 04 14◦ 18 04 14◦ 18 04 14◦ 18 04 14◦ 13 47 14◦ 13 47 14◦ 13 47 14◦ 13 47 14◦ 12 07 Aluminium granulitic quartzite Calc-silicate Khondalito-kinzigitic granulite Khondalito-kinzigitic granulite Pelitic granulite Granulitic quartzite Pelitic granulite Granulitic anatectic gneiss Granulitic gneiss Quartzitic granulite Quartzo-feldspathic granulite Metatectic granulite semi-pelitic granulite Granulitic quartzite qtz, pl.ap, Ksp.mp, Ti-bi, ga, sil.p, crd, rt, Fe-Ti ox, chl2, pn2, mus2 per, for, phl, grt, graph, zn, serp2, chl2 qtz, pl.ap, Ksp.mp, bi, crd, ilm, zn qtz, pl.ap, Ksp.mp, bi, crd, ilm, zn qtz, pl.ap, Ksp.mp, Ti-bi, ga, sil.p, crd, zn, graph, rt, chl2, pn2, mus2 qtz, pl.ap, Ksp, bi, sil.p, ga, sp, zn, ap qtz, pl, Ksp.mp, bi, ga, sil.p, crd, spl, dsp2, pn2 qtz, Ksp.mp, Ti-bi, ga, crd, chl2 qtz, pl.ap, Ksp, crd, Ti-bi, ga, pn2, sc2, chl2 qtz, Ksp.mp, bi, grt, sil.p, graph, zn, ap, chl2, mus2 qtz, pl.ap, Ksp.mp, bi, sil.p, ga, spl, rt, Fe-Ti ox, chl, mus qtz, pl.ap, Ksp.mp, Ti-bi, ga, sil.p, crd, spl, chl2, mus2, pn2, dsp2 qtz, pl.ap, Ksp.mp, Ti-bi, ga, crd, spl, chl2, ms2, pn2, dsp2 qtz, pl.ap, Ti-bi, ga, zn, ap, chl2 , 108◦ 29 01 , 108◦ 29 01 , 108◦ 45 11 , 107◦ 52 21 , 108◦ 29 01 , 108◦ 29 01 , 108◦ 29 01 , 108◦ 29 01 , 108◦ 29 01 , 108◦ 30 53 , 108◦ 30 53 , 108◦ 30 53 , 108◦ 30 53 , 108◦ 32 04 Note: ap, antiperthite; mp, Mesoperthite; p, prismatic; 2, secondary paragenesis All mineral abbreviations in the table and in the text are of Powell and Holland (2001) 152 Table Representative analyses of the main mineral phases in the granulites terranes of the Kontum Block (Song Ba river: Vn356a, Vn362, Vn363; Song Bien Brook: Vn413, Vn414, Vn415) Vn413/Vn413-S1 and Vn414/Vn414BB/Vn414S4/Vn414-1◦ Vn414-2/VN414p represent different compositional layers in two representative samples from the two main outcrops granulitic area (a) Spinels (sp) The number of ions in the spinel formula is based on oxygens and the sum of cations is recalculated to (sp2: secondary spinel in the reactional cordierite corona around garnet; cmp incl., composite inclusion; mph, mesoperthite); (b) K-feldspars (ksp) The number of ions in the K-feldspar formula is based on oxygens (Xab, Xalbite; Xor, Xorthose; Xan, Xanorthite); (c) Plagioclases (pl) The number of ions in the plagioclase formula is based on oxygens (Xab, Xalbite; Xor, Xorthose; Xan, Xanorthite pl2: secondary plagioclase in the cordierite-spinel reactional corona around garnet); (d) Biotites (bi) and phlogopites (phl) The number of ions in the black-micas formula is based on 10 oxygens and (OH) (synf., synfolial; incl in, inclusion in; /, against (e.g bi/ga: biotite against garnet); crd2: secondary cordierite in the reactional corona around garnet; gpt: graphite; cmp incl.: composite inclusion); (e) Garnets (ga) The number of ions in the garnet formula is based on 12 oxygens and the sum of cations is recalculated to (Xalm, X almandin; Xpyr, Xpyrope; Xgro, Xgrossular; Xspe, X spessartite); (f) Cordierites (crd) The number of ions in the cordierite formula is based on 10 oxygens (crd1, primary with biotite and sillimanite; crd2, reactional cordierite); (g) Prismatic sillimanite (sil) The number of ions in the sillimanite formula is based on oxygens; (h) Ilmenites (il) The number of ions in the ilmenite formula is based on oxygens and the sum of cations is recalculated to (sulph, Fe-sulphide; Xil, Xilmenite; Xhm, Xhematite; Xgk, Xgeikileite; Xpy, X pyrophanite); (i) magnetites (mt) The number of ions in the magnetite formula is based on oxygens and the sum of cations is recalculated to (Xmt, Xmagnetite; Xulv, Xulvöspinel) (a) Spinel (spl) Vn363 sp2 core Vn414.S4 matrix sp core Vn414.S4 cmp incl in ga Vn414B incl in ga core Vn414B matrix sp rim Vn414B incl in bi core Vn414BNL inc in sil core Vn413 incl in mph core Vn415 sp2 incl bi core Vn415NL sp2 core 0.19 0.08 60.91 0.26 1.49 8.66 25.55 0.06 3.72 0.00 0.00 0.00 100.93 0.005 0.002 1.950 0.006 0.030 0.351 0.580 0.001 0.075 0.000 0.000 0.000 3.000 0.623 0.015 0.17 0.23 58.34 0.41 1.51 3.89 35.27 0.10 0.55 0.00 0.00 0.00 100.50 0.005 0.005 1.939 0.009 0.032 0.164 0.832 0.003 0.012 0.000 0.000 0.000 3.000 0.836 0.016 0.15 0.00 60.22 0.00 1.72 7.58 25.37 0.07 5.21 0.01 0.00 0.00 100.32 0.004 0.000 1.956 0.000 0.036 0.311 0.585 0.002 0.106 0.000 0.000 0.000 3.000 0.653 0.018 0.17 0.00 60.92 0.03 1.16 8.59 23.40 0.07 5.75 0.01 0.00 0.00 100.09 0.005 0.000 1.966 0.001 0.024 0.351 0.536 0.002 0.116 0.000 0.000 0.000 3.000 0.605 0.012 0.13 0.01 59.82 0.09 2.89 6.68 29.69 0.05 2.46 0.00 0.00 0.00 101.82 0.003 0.000 1.931 0.002 0.060 0.273 0.680 0.001 0.050 0.000 0.000 0.000 3.000 0.714 0.030 0.17 0.03 57.55 0.12 2.63 3.24 33.60 0.11 3.07 0.00 0.00 0.01 100.55 0.005 0.001 1.930 0.003 0.056 0.138 0.800 0.003 0.065 0.000 0.000 0.000 3.000 0.853 0.028 0.17 0.04 58.51 0.06 1.22 3.16 24.08 0.02 14.04 0.04 0.00 0.03 101.36 0.005 0.001 1.962 0.001 0.026 0.134 0.573 0.000 0.295 0.001 0.000 0.001 3.000 0.810 0.013 0.11 0.03 57.52 0.30 2.97 5.04 29.78 0.13 3.85 0.04 0.00 0.00 99.76 0.003 0.001 1.922 0.007 0.063 0.213 0.706 0.003 0.081 0.001 0.000 0.000 3.000 0.768 0.032 0.08 0.01 57.79 0.05 3.57 3.55 35.69 0.14 0.37 0.03 0.00 0.01 101.29 0.002 0.000 1.919 0.001 0.076 0.149 0.841 0.003 0.008 0.001 0.000 0.000 3.000 0.849 0.038 0.20 0.06 57.00 0.17 3.48 3.13 36.06 0.22 0.55 0.00 0.00 0.01 100.90 0.006 0.001 1.908 0.004 0.074 0.133 0.857 0.005 0.011 0.000 0.000 0.000 3.000 0.866 0.037 0.28 0.00 58.53 0.02 3.28 6.22 31.73 0.14 0.47 0.02 0.00 0.00 100.69 0.008 0.000 1.915 0.000 0.069 0.257 0.737 0.003 0.010 0.001 0.000 0.000 3.000 0.741 0.035 Vn362 ksp2 Vn362 ksp Vn362 antiperthite Vn362NL antiperthite Vn363 ksp Vn363 antiperthite VNn14B ksp VNn14B ksp VNn13 ksp Vn413 ksp (b) K-felspars (Ksp) Vn362 ksp SiO2 TiO2 Al2 O3 Cr2 O3 MgO FeO MnO 63.84 0.03 19.56 0.01 0.01 0.03 0.02 63.4 0.02 19.13 0 0.31 64.52 0.04 19.15 0 0.04 0.01 63.84 19.07 0.01 0.01 0.05 64.55 0.02 19.26 0.01 0.01 0.02 0.01 63.26 0.03 18.86 0.01 0.17 64.15 0.03 19.11 0 0.04 63.79 0.04 19.21 0.02 0.02 0.02 64.25 19.23 0.01 0.01 0.01 64.66 19.02 0 0.03 64.6 0.01 19.08 0.02 0.05 V.V Tích et al / Journal of Geodynamics 69 (2013) 148–164 SiO2 TiO2 Al2 O3 Cr2 O3 Fe2 O3 MgO FeO MnO ZnO CaO Na2 O K2 O Sum Si Ti Al Cr Fe3 Mg Fe2 Mn Zn Ca Na K Sum XFe2 XFe3 Vn362 incl in ga core 0.35 2.61 13.02 98.84 2.947 0.001 1.048 0 0.012 0 0.017 0.235 0.772 5.032 0.02 0.23 0.75 0.12 1.73 14.41 100.02 2.967 0.001 1.038 0 0.001 0.001 0.006 0.154 0.845 5.013 0.01 0.15 0.84 0.21 0.92 15.46 99.57 2.962 1.043 0.001 0.002 0 0.01 0.083 0.915 5.016 0.01 0.08 0.91 0.03 0.31 1.65 13.7 99.58 2.969 0.001 1.044 0.001 0.001 0.001 0.001 0.015 0.147 0.804 4.984 0.02 0.15 0.83 0.23 1.64 14.15 98.35 2.961 0.001 1.04 0.001 0.007 0 0.011 0.149 0.845 5.015 0.01 0.15 0.84 0.02 0.27 1.69 14.43 99.75 2.961 0.001 1.04 0 0.001 0.001 0.013 0.152 0.849 5.019 0.01 0.15 0.84 0.01 0.08 0.82 15.9 99.89 2.955 0.001 1.049 0.002 0.001 0.001 0.004 0.073 0.94 5.026 0.07 0.92 0.2 1.56 14.85 100.11 2.959 1.044 0.001 0 0.01 0.139 0.872 5.025 0.01 0.14 0.85 0.03 0.92 15.7 100.36 2.974 1.031 0 0.001 0 0.001 0.082 0.921 5.012 0.08 0.92 0.03 0.82 15.89 100.5 2.97 0.001 1.034 0.001 0.002 0 0.002 0.073 0.932 5.014 0.07 0.93 (c) Plagioclase (pl) Vn356a pl SiO2 TiO2 Al2 O3 Cr2 O3 MgO FeO MnO ZnO CaO Na2 O K2 O Sum Si Ti Al Cr Mg Fe2 Mn Zn Ca Na K Sum Xan Xab Xor 64.99 0.01 20.23 0.02 0.05 0 0.34 7.43 3.86 96.92 2.956 1.085 0.001 0.002 0 0.017 0.655 0.224 4.941 0.02 0.73 0.25 Vn362 pl 57.61 0.01 27.15 0 0.24 0.01 0.02 8.74 6.59 0.19 100.56 2.57 1.427 0 0.009 0.001 0.418 0.57 0.011 5.006 0.42 0.57 0.01 Vn363 pl 58.08 0.03 25.9 0.01 0.02 0.03 7.59 7.05 0.35 99.07 2.622 0.001 1.378 0 0.001 0.001 0.367 0.617 0.02 5.007 0.37 0.61 0.02 Vn363 pl2 55.89 28.31 0 0.51 0 9.89 5.94 0.19 100.73 2.501 1.494 0 0.019 0 0.474 0.516 0.011 5.015 0.47 0.52 0.01 Vn363 pl2 56.34 0.05 27.91 0 0.37 0 9.47 6.2 0.15 100.49 2.523 0.002 1.473 0 0.014 0 0.454 0.538 0.008 5.012 0.45 0.54 0.01 Vn414.S4 pl 60.66 24.41 0.03 0.3 0.01 0.07 5.68 8.17 0.09 99.42 2.713 1.286 0.001 0.011 0.001 0.002 0.272 0.708 0.005 0.28 0.72 0.01 Vn414.S4 pl 60.19 25.06 0.03 0.09 0.01 7.84 0.14 99.36 2.691 1.32 0.001 0.003 0 0.287 0.68 0.008 4.992 0.29 0.7 0.01 Vn414B pl 60.86 0.01 24.94 0 0.09 0.01 5.95 8.53 0.12 100.51 2.695 1.302 0 0.003 0 0.282 0.732 0.007 5.023 0.28 0.72 0.01 Vn414B pl 59.43 0.02 24.89 0.01 0.13 0.02 0.01 7.81 0.6 98.92 2.68 0.001 1.323 0 0.005 0.001 0.29 0.683 0.034 5.017 0.29 0.68 0.03 Vn413 pl 67.14 21.43 0.01 0.01 0.1 0 1.34 10.87 0.08 100.99 2.914 1.096 0.001 0.001 0.004 0 0.062 0.915 0.004 4.997 0.06 0.93 Vn413-S1 pl 66.1 0.02 20.97 0 0.01 0.02 1.34 8.04 3.86 100.37 2.921 0.001 1.092 0 0.001 0.001 0.063 0.689 0.218 4.985 0.07 0.71 0.22 Vn415 pl 53.11 0.01 29.95 0 0.74 0 11.76 4.76 0.04 100.36 2.4 1.595 0 0.028 0 0.569 0.417 0.002 5.012 0.58 0.42 Vn415 pl 57.17 0.03 27.49 0.01 0.52 0.01 0.02 8.86 6.55 0.06 100.71 2.55 0.001 1.445 0 0.02 0.001 0.423 0.566 0.004 5.011 0.43 0.57 Vn415 pl2 51.72 30.7 0.01 0.2 5.15 0.02 0.06 8.06 6.08 0.22 102.23 2.336 1.635 0.014 0.195 0.001 0.002 0.39 0.533 0.013 5.118 0.42 0.57 0.01 V.V Tích et al / Journal of Geodynamics 69 (2013) 148–164 0.64 2.7 12.9 99.74 2.937 0.001 1.06 0.001 0.001 0.001 0.032 0.24 0.757 5.031 0.03 0.23 0.74 CaO Na2 O K2 O Sum Si Ti Al Cr Mg Fe2 Mn Zn Ca Na K Sum Xan Xab Xor 153 154 Table (Continued ) (d) Biotite (bi) Vn356a bi synf core Vn362 synf./ga core Vn362 synf core Vn362 incl in ga core Vn363 incl in ga core Vn414.S4 synf phl/ga core Vn414B synf core Vn414 synf rim Vn414B synf/ga rim Vn413 synf./sil core Vn415 included in sp core Vn415NL incl in ga core 37.71 6.0 17.76 0.02 12.81 13.03 0.03 0.08 0.11 0.14 9.35 4.14 101.17 2.726 0.326 1.514 0.001 1.381 0.788 0.002 0.004 0.008 0.02 0.862 9.631 0.363 38.79 5.05 17.08 12.03 12.42 0.02 0.04 0.09 0.19 9.3 4.08 99.1 2.846 0.278 1.477 1.316 0.762 0.001 0.002 0.007 0.028 0.871 9.587 0.367 36.66 4.64 16.15 0.05 14 13.84 0.07 0.22 9.91 4.03 99.55 2.726 0.259 1.415 0.003 1.552 0.86 0.004 0.032 0.94 9.792 0.357 37.75 3.15 16.3 0.05 15.36 13.52 0.02 0.03 0.02 0.22 9.68 4.08 100.17 2.773 0.174 1.411 0.003 1.682 0.83 0.001 0.001 0.002 0.032 0.907 9.816 0.331 36.43 5.99 16.3 0.05 14.77 12.12 0.02 0.03 0.03 0.34 9.47 4.07 99.61 2.684 0.332 1.415 0.003 1.622 0.747 0.001 0.001 0.002 0.049 0.89 9.745 0.315 36.83 5.95 15.32 0.12 12.63 16.15 0.04 0.02 0.17 9.64 4.04 100.9 2.728 0.331 1.337 0.007 1.394 0.002 0.001 0.025 0.91 9.736 0.418 37.3 0.92 18.46 0.02 18.01 9.74 0.02 0.03 0.01 0.08 9.99 4.09 98.66 2.733 0.05 1.594 0.001 1.967 0.597 0.001 0.002 0.001 0.012 0.933 9.891 0.233 35.53 3.4 17.9 0.02 13.43 14.94 0 0.02 0.14 9.99 99.37 2.66 0.191 1.58 0.001 1.5 0.935 0 0.002 0.021 0.955 9.846 0.384 35.94 3.14 18.21 12.37 16.15 0.02 0.07 0.01 0.06 10.32 4.02 100.3 2.681 0.176 1.601 1.375 1.007 0.001 0.004 0.001 0.009 0.982 9.838 0.423 36.81 2.98 17.46 0.02 14.45 13.82 0.02 0.03 0.12 10.23 4.05 99.99 2.721 0.166 1.522 0.001 1.592 0.855 0.001 0.002 0.017 0.965 9.842 0.349 33.62 2.48 18.31 10.66 19.5 0.03 0.02 0.22 9.79 3.87 98.5 2.603 0.144 1.672 1.23 1.263 0.002 0.001 0.034 0.968 9.917 0.507 36.35 2.35 18.36 13.13 15.87 0.06 0 0.18 9.64 4.03 99.98 2.703 0.132 1.609 1.455 0.987 0.004 0 0.026 0.914 9.831 0.404 35.57 5.22 16.62 0.03 16.76 11.25 0.04 0.04 0.01 0.41 9.35 4.06 99.35 2.622 0.289 1.444 0.001 1.841 0.694 0.003 0.002 0.001 0.058 0.879 9.835 0.274 (e) Garnet (Ga) SiO2 TiO2 Al2 O3 Cr2 O3 Fe2 O3 MgO FeO MnO ZnO CaO Na2 O K2 O Sum Si Ti Vn355 core Vn362 core Vn362 rim/bi Vn363NL core Vn363 core 414-S4 core Vn414BNL rim/qz Vn414BNL rim/bi Vn414BNL rim/spl Vn413 incl in pl Vn415 core Vn803 core Vn803 rim/qz 38.000 0.050 21.840 0.000 2.270 7.540 30.750 1.010 0.020 0.170 0.000 0.000 101.660 2.936 0.003 37.290 0.050 22.380 0.010 2.990 8.370 27.340 0.480 0.000 1.440 0.000 0.000 100.360 2.888 0.003 36.990 0.070 22.150 0.040 2.510 5.790 31.460 0.800 0.000 1.220 0.000 0.040 101.060 2.900 0.004 38.330 0.050 22.170 0.020 2.280 9.540 26.740 0.380 0.040 1.310 0.010 0.000 100.880 2.932 0.003 37.860 0.040 21.810 0.030 1.160 5.800 32.740 0.540 0.000 1.270 0.010 0.000 101.260 2.959 0.002 37.470 0.020 21.560 0.000 1.720 6.430 30.840 1.540 0.000 0.720 0.000 0.010 100.310 2.949 0.001 37.270 0.010 21.390 0.000 2.110 6.070 31.170 1.480 0.010 0.810 0.010 0.000 100.330 2.942 0.001 36.770 0.010 21.210 0.010 2.180 4.620 33.060 1.490 0.000 0.810 0.020 0.010 100.200 2.937 0.000 37.370 0.000 21.550 0.020 1.420 5.150 32.930 1.470 0.060 0.790 0.000 0.000 100.770 2.953 0.000 34.840 0.010 22.350 0.100 1.290 3.640 32.610 1.840 0.000 0.390 0.040 0.000 97.110 2.873 0.000 37.990 0.040 21.790 0.010 1.840 6.530 30.210 1.900 0.000 1.320 0.000 0.000 101.630 2.947 0.002 37.770 0.060 22.080 0.020 2.100 7.770 29.110 0.560 0.030 1.260 0.010 0.000 100.770 2.927 0.004 37.790 0.040 22.120 0.020 2.290 7.780 29.370 0.580 0.060 0.960 0.030 0.000 101.040 2.924 0.003 V.V Tích et al / Journal of Geodynamics 69 (2013) 148–164 SiO2 TiO2 Al2 O3 Cr2 O3 MgO FeO MnO ZnO CaO Na2 O K2 O H2 O Sum Si Ti Al Cr Mg Fe2 Mn Zn Ca Na K OH Sum XFe Vn353 bi synf core 1.990 0.000 0.132 0.869 1.987 0.066 0.001 0.014 0.001 0.000 8.000 0.696 0.680 0.300 0.000 0.020 2.044 0.001 0.174 0.967 1.771 0.032 0.000 0.120 0.001 0.000 8.000 0.647 0.610 0.330 0.040 0.010 2.046 0.002 0.148 0.677 2.063 0.053 0.000 0.102 0.000 0.004 8.000 0.753 0.710 0.230 0.040 0.020 1.999 0.001 0.131 1.087 1.710 0.025 0.002 0.107 0.002 0.000 8.000 0.611 0.580 0.370 0.040 0.010 2.009 0.002 0.068 0.676 2.140 0.036 0.000 0.107 0.001 0.000 8.000 0.760 0.720 0.230 0.040 0.010 2.000 0.000 0.102 0.754 2.030 0.103 0.000 0.061 0.000 0.001 8.000 0.729 0.690 0.260 0.020 0.030 1.990 0.000 0.125 0.714 2.058 0.099 0.000 0.068 0.001 0.000 8.000 0.742 0.700 0.240 0.020 0.030 1.997 0.001 0.131 0.550 2.208 0.101 0.000 0.070 0.004 0.001 8.000 0.801 0.750 0.190 0.020 0.030 2.008 0.001 0.084 0.607 2.177 0.099 0.004 0.067 0.000 0.001 8.000 0.782 0.740 0.210 0.020 0.030 2.173 0.006 0.080 0.448 2.249 0.129 0.000 0.035 0.006 0.000 8.000 0.834 0.790 0.160 0.010 0.050 1.992 0.001 0.107 0.755 1.960 0.125 0.000 0.110 0.000 0.000 8.000 0.722 0.660 0.260 0.040 0.040 2.017 0.001 0.122 0.898 1.886 0.037 0.001 0.105 0.002 0.000 8.000 0.677 0.640 0.310 0.040 0.010 2.017 0.001 0.134 0.898 1.900 0.038 0.003 0.079 0.004 0.000 8.000 0.679 0.650 0.310 0.030 0.010 (f) Cordierite (Crd) SiO2 TiO2 Al2 O3 Cr2 O3 MgO FeO MnO ZnO CaO Na2 O K2 O Sum Si Ti Al Cr Mg Fe2 Mn Zn Ca Na K Sum XFe Vn413 crd1/bi core Vn413 crd1/bi rim Vn363 crd2 core Vn363 crd2/ga rim Vn414-1 rim Vn414-2 crd2/sp rim Vn414-2 crd2/ga rim Vn415 crd2/ga rim Vn415 crd2/bi rim 47.40 0.01 33.39 0.01 8.56 8.68 0.10 0.00 0.00 0.11 0.00 98.28 4.901 0.001 4.069 0.001 1.320 0.751 0.009 0.000 0.000 0.023 0.000 11.075 0.363 47.69 0.00 34.24 0.00 8.79 8.52 0.12 0.01 0.00 0.12 0.05 99.56 4.866 0.000 4.118 0.000 1.337 0.727 0.010 0.001 0.000 0.024 0.007 11.090 0.352 48.12 33.41 7.79 9.51 0.06 0.01 0.04 0.07 99.01 4.949 4.049 1.193 0.817 0.005 0.001 0.004 0.014 0.001 11.034 0.407 48.37 0.02 33.6 0.01 8.18 8.88 0.08 0.01 0.02 0.05 0.01 99.22 4.948 0.002 4.051 0.001 1.248 0.759 0.006 0.001 0.002 0.01 0.001 11.03 0.378 47.70 0.02 33.11 0.01 8.41 8.81 0.20 0.00 0.01 0.10 0.00 98.39 4.929 0.002 4.033 0.001 1.296 0.762 0.017 0.000 0.001 0.020 0.000 11.062 0.370 47.63 0.01 33.56 8.9 7.94 0.12 0.04 0.02 0.06 98.29 4.906 0.001 4.075 1.367 0.684 0.01 0.003 0.002 0.012 0.001 11.062 0.333 47.7 33.64 0.01 9.23 7.32 0.07 0.02 0.01 0.04 98.04 4.909 4.081 1.416 0.63 0.006 0.001 0.001 0.008 11.054 0.308 49.26 33.72 9.1 7.23 0.14 0.01 0.08 99.54 4.983 4.021 1.371 0.611 0.012 0.001 0.016 11.015 0.308 48.93 33.92 0.01 10.3 5.03 0.09 0.02 0.02 0.06 98.39 4.96 4.052 0.001 1.556 0.427 0.008 0.001 0.002 0.012 11.02 0.215 V.V Tích et al / Journal of Geodynamics 69 (2013) 148–164 Al Cr Fe3 Mg Fe2 Mn Zn Ca Na K Sum XFe Xalm Xpyr Xgro Xspe 155 156 Table (Continued ) (g) Prismatic sillimanite (sil) Vn353 Vn362 Vn362 Vn363 Vn414.S4 Vn414.S4 36.1 0.04 63.92 0.07 0.2 0.02 0.04 0.05 0 100.45 0.972 0.001 2.028 0.001 0.004 0.001 0.002 0.001 0 3.01 39.73 0.04 60.1 0.02 1.97 0.03 0.6 0.13 0.07 0.04 102.74 1.05 0.001 1.872 0.039 0.001 0.024 0.004 0.004 0.001 2.995 36.24 0.01 62.93 0.04 1.16 0.12 0.02 0.08 0.01 100.61 0.977 0.001 0.024 0.005 0.002 0 3.01 36.41 0.06 63.96 0.05 0.28 0.01 0.03 0.01 0 100.81 0.976 0.001 2.022 0.001 0.006 0.001 0 0 3.008 35.62 0.01 63.99 0.03 1.27 0 0.13 0 0.01 101.07 0.958 2.028 0.001 0.026 0 0.003 0 3.015 35.84 0.08 63.83 0.03 1.1 0.01 0.08 0.01 0.01 100.99 0.963 0.002 2.022 0.001 0.022 0 0.002 0 3.013 Vn414BNL 35.94 0.02 62.85 0.03 0.96 0.01 0.02 0.01 0.01 99.85 0.975 2.011 0.001 0.02 0.001 0 0 3.009 Vn414BNL 35.13 0.01 64.04 0.02 0.77 0.01 0.03 0.01 0.01 100.02 0.952 2.046 0.016 0 0.001 0.001 3.017 Vn413 34.95 63.37 0.02 1.13 0.01 0.02 0.01 0.01 99.52 0.953 2.038 0.023 0 0 0 3.016 Vn415 36.42 63.22 0.01 0.9 0.01 0.05 0.01 0.01 100.64 0.98 2.006 0.018 0.002 0 0 3.008 Vn415 Vn803 Vn803 36.24 0.02 63.22 0.06 1.19 0.03 0.01 0.01 0.01 100.77 0.975 2.006 0.001 0.024 0.001 0 0 3.009 36.3 0.03 63.76 0.04 0.26 0.03 0 0 100.44 0.977 0.001 2.023 0.001 0.005 0.001 0 0 3.008 36.16 0.03 64.01 0.06 0.56 0.01 0.01 0.01 0.01 100.86 0.97 0.001 2.025 0.001 0.011 0 0 0.001 3.01 (h) Ilmenite (il) Vn363/sp2, crd2 core 0.16 SiO2 54.83 TiO2 0.05 Al2 O3 0.09 Cr2 O3 Fe2 O3 MgO 0.26 47.55 FeO 0.25 MnO ZnO 0.01 CaO 0.06 Na2 O K2 O Sum 103.27 0.004 Si 1.002 Ti 0.001 Al 0.002 Cr Fe3 0.01 Mg Fe2 0.967 0.005 Mn Vn363/crd2 rim 0.2 50.7 0.06 0.09 5.21 0.05 44.5 0.78 0.02 0.07 0.11 101.79 0.005 0.946 0.002 0.002 0.097 0.002 0.924 0.016 Vn363/crd2, sulph, sp2 rim 0.92 51.03 0.74 0.01 1.16 0.66 44.4 1.2 0.01 0.02 0.05 100.2 0.023 0.956 0.022 0.022 0.025 0.925 0.025 Vn414-S4 in crd2/sp2 rim 0.11 51.01 0.02 0.05 0.98 0.03 45.22 0.67 0.01 0.02 98.1 0.003 0.987 0.001 0.001 0.019 0.001 0.973 0.015 Vn414-1 in crd2/mt, sp core 0.12 48.86 0.03 0.00 5.38 0.06 43.34 0.57 0.05 0.00 0.00 0.00 98.42 0.003 0.944 0.001 0.000 0.104 0.002 0.932 0.012 Vn414B matrix il rim/bi 0.14 50.66 0.03 3.59 0.04 44.76 0.64 0.06 0.01 0.02 0.02 99.97 0.004 0.963 0.001 0.068 0.002 0.946 0.014 Vn413/mt core Vn413 incl in mph core 0.38 47.47 0.22 0.03 11.49 0.09 41.39 1.36 0.03 0.00 0.02 0.03 102.52 0.010 0.881 0.007 0.001 0.213 0.003 0.854 0.028 0.14 46.89 0.00 0.03 7.91 0.01 41.88 0.37 0.00 0.01 0.00 0.01 97.26 0.004 0.919 0.000 0.001 0.155 0.001 0.912 0.008 Vn415/bi12 rim 0.21 49.69 0.16 0.02 4.42 0.08 43.44 0.87 0.02 0.04 0.09 99.04 0.005 0.952 0.005 0.085 0.003 0.926 0.019 Vn415 in crd2 rim/sp2 0.64 49.61 0.32 0.06 4.39 0.42 42.61 1.46 0.02 0 0.17 99.7 0.016 0.94 0.01 0.001 0.083 0.016 0.897 0.031 Vn803/ga rim 0.13 53.12 0.02 0.00 0.00 0.04 45.40 0.40 0.20 0.03 0.00 0.01 99.34 0.003 1.009 0.001 0.000 0.000 0.001 0.959 0.009 V.V Tích et al / Journal of Geodynamics 69 (2013) 148–164 SiO2 TiO2 Al2 O3 Cr2 O3 Fe2 O3 Mn2 O3 MgO ZnO CaO Na2 O K2 O Sum Si Ti Al Cr Fe3 Mn3 Mg Zn Ca Na K Sum Zn Ca Na K Sum Xil Xhm Xgk Xpy 0 0.003 1.994 0.99 0.01 0.01 0.002 0.004 0.93 0.05 0.02 0 0.002 0.94 0.01 0.02 0.03 0 0.001 0.97 0.01 0.01 0.001 0.000 0.000 0.000 2.000 0.93 0.05 0.00 0.01 0.001 0.001 0.001 0.95 0.03 0.01 0.001 0.000 0.001 0.001 2.000 0.86 0.11 0.00 0.03 0.000 0.000 0.000 0.000 2.000 0.91 0.08 0.00 0.01 0 0.002 0.003 0.94 0.04 0.02 0 0.005 0.91 0.04 0.02 0.03 0.004 0.001 0.000 0.000 1.987 0.99 0.00 0.00 0.01 SiO2 TiO2 Al2 O3 Cr2 O3 Fe2 O3 MgO FeO MnO ZnO CaO Na2 O K2 O Sum Si Ti Al Cr Fe3 Mg Fe2 Mn Zn Ca Na K Sum Xmt Xulv Vn414-S4 Vn414-1 Vn413 Vn413 Vn415 Vn415NL 0.14 0.17 0.33 0.09 66.55 0.06 30.49 0.05 0.07 0.02 0.02 97.98 0.005 0.005 0.015 0.003 1.963 0.003 0.999 0.002 0.002 0.001 0.001 0.995 0.005 0.14 0.14 0.51 0.17 67.49 0.03 31.32 0.02 0.01 0.00 0.00 0.00 99.83 0.006 0.004 0.023 0.005 1.953 0.001 1.007 0.001 0.000 0.000 0.000 0.000 3.000 0.996 0.004 0.08 0.12 0.37 0.29 61.93 0.02 30.57 0.00 0.00 0.00 0.00 0.00 100.39 0.003 0.003 0.016 0.008 1.964 0.001 1.005 0.000 0.000 0.000 0.000 0.000 3.000 0.997 0.003 0.11 0.04 0.32 0.01 67.79 0.03 30.90 0.00 0.01 0.03 0.00 0.01 99.26 0.004 0.001 0.014 0.000 1.975 0.002 1.001 0.000 0.000 0.001 0.000 0.000 3.000 0.999 0.001 0.19 0.11 0.32 0.02 68 0.03 31.28 0.02 0.04 0.05 0 100.07 0.007 0.003 0.014 0.001 1.964 0.002 1.004 0.001 0.001 0.002 0 0.997 0.003 0.15 0.19 0.40 0.06 68.23 0.00 31.53 0.02 0.02 0.00 0.02 0.00 100.63 0.006 0.005 0.018 0.002 1.960 0.000 1.006 0.001 0.001 0.000 0.002 0.000 3.000 0.995 0.005 V.V Tích et al / Journal of Geodynamics 69 (2013) 148–164 (i) Magnetite (mt) 157 158 V.V Tích et al / Journal of Geodynamics 69 (2013) 148–164 Fig (a) Oval garnet (ga) in the main mylonitic shear zone (mylonitic granulite Vn355 (X 5)); (b) skeletal habitus of the prismatic sillimanite (sil) in a biotite, cordierite, sillimanite leucosome (Vn413) (X 5) Fig (a) Matrix mesoperthitic K-felspars (Ksp) in anatectic granulite (Vn413); (b) a skeletal and dendritic sillimanite in textural equilibrium with biotite in granulitic leucosome Vn413 (X 5); (c) armored inclusions of spinel (spl), biotite (bi), sillimanite (sil) and quartz (qtz) in garnet (ga) of the anatectic granulite Vn362 (X5); (d) spinel, quartz and biotite still in contact in composite armored inclusions in garnet (ga) (banded granulite Vn414) (X 5); (e) Garnet phenoblast with one relic muscovite flake, quartz, green spinel and K-feldspar in inclusions (Vn414) (X 5); (f) matrix biotite (bi) in textural equilibrium with garnet (ga) includes matrix Zn-hercynite (spl) in a compositional layer of the banded granulite (Vn414) (X10) V.V Tích et al / Journal of Geodynamics 69 (2013) 148–164 159 Fig (a) Primary garnet (ga) in textural equilibrium with euhedral prismatic sillimanite (sil) in granulite Vn803 (X 5); (b) garnet phenoblast showing needles of sillimanite only on the garnet rim Note the cordierite (crd)-hercynite (he) corona around garnet (granulite Vn363) (X 5); (c) cordierite (crd), hercynite (he) corona around primary garnet porphyroblast External reacting sillimanite is corroded Biotites are present as a matrix phase, as armored inclusions in garnet or in sillimanite and in the corona (granulite Vn415) (X 5); (d) deformed cordierite (crd), hercynite (he), plagioclase-quartz corona between garnet (ga) and prismatic sillimanite (sil) Secondary quartz and plagioclase are always present in such corona but are not visible at that scale Cordierite is sometimes pinnitized (crd.p) (granulite Vn363) (X 5); (e) Late generation of biotite surrounds hercynite in a cordierite corona around an amoeboid garnet (granulite Vn415) (X10); (f) Inclusion plagioclase, quartz in garnet (granulite sample Vn415) (X 5) xenotime are exceptional Orthopyroxene is lacking either in the granulitic leucosomes or paleosomes and melanosomes This mineral is totally absent in all the granulite metapelites The paragenesis orthopyroxene/sillimanite and orthopyroxene/cordierite are always associated or not with biotite, Ca-amphiboles or Caclinopyroxene and noritic magmatic intrusive bories Further more the high temperature assemblages sapphirine quartz has not been found neither in the granulite non in the charnockites s.l in our investigated Kan Nack study area Primary muscovite has already disappeared in the matrix but exceptionally persists as scarce armored inclusions in a few garnet porphyroblasts (Fig 4e) In the zincian granulitic layer green Fe–Zn spinels are also observed in equilibrium with garnet, biotite, sillimanite or in armored inclusion in these three phases (Vn414) Associated Fe–Zn spinel and cordierite have been also observed in corona reactional texture around garnet against prismatic sillimanite (Fig 5, Vn415–Vn363) The equilibrium association spinel + quartz is scarce but has been observed in one time in the zincian rock, indicating very low pressure during the decompression 3.2 Mineral chemistry and paragenetic analysis of the widespread pelitic and semipelitic granulites According to the composition of the rock layers, the chemistry of mineral phases is subjected to small variation We will describe here in detail the succession of mineral assemblage as show by the wide spread corona reaction texture and the mineral chemistry of these pelitic and semipelitic granulites Almandin-pyrope garnet porphyroblast (0.607 < XFe < 0.863; O.58 < Xalm < 0.80; 0.13 < Xpyr < 0.37; Xgro < 0.04; Xspe