Abstract:Even a small amount of water can have a disproportionately large effect on physical and chemical properties of minerals or rocks, and hence knowledge of its speciation, concentration and distribution is crucial for understanding the composition, structure, physical and chemical characteristics and geodynamics of the lithospheric mantle. Peridotite xenoliths hosted by alkali magma are representative samples from the lithospheric mantle, and their water content may provide information about the distribution of water in the lithospheric mantle. Peridotite xenoliths are hosted by both Mesozoic and Cenozoic basalts in eastern China. Although some research work has been done for peridotite xenoliths hosted by Cenozoic basalts, investigations on peridotites hosted by Mesozoic basalts remain insufficient. This paper presents major and trace element concentrations of minerals from peridotite xenoliths hosted by Early Jurassic basalts in Ningyuan, Hunan Province, which were obtained by EMP and LA-ICPMS respectively. Covariations between major and trace elements suggest that the peridotite xenoliths are relicts of primary mantle after low-degree partial melting. Elevated content of highly incompatible elements (Th, U, La, Ce etc.) in some clinopyroxenes demonstrates that the Ningyuan lithospheric mantle has undergone mantle metasomatism. Based on low La/Yb and high Ti/Eu ratios of clinopyroxenes, the authors hold that the metasomatic agent was silicate melt rather than carbonatite melt. Micro-FTIR analysis demonstrates that both clinopyroxene and orthopyroxene display prominent absorption bands in 3000～3700 cm-1 region, which resulted from hydroxyl defect in their structure. The calculated water content (H2O wt.) of clinopyroxene and orthopyroxene ranges from 147×10-6 to 461×10-6 and 40×10-6 to 126×10-6 respec-tively. Based on the water content and mineral model, it is estimated that the whole-rock water content of the Ninyuan peridotites should vary in the range of 34×10-6～108 ×10-6. In combination with the previously reported data, it is held that the water content of the Mesozoic lithospheric mantle of Ningyuan is much higher than that of the Cenozoic lithospheric mantle of the North China Craton (mostly <30 ×10-6). The low water content of the Cenozoic lithospheric mantle in the North China Craton is attributed to the heating action by an upwelling asthenosphere flow in consistent with NCC lithospheric thinning during the Late Mesozoic to Early Cenozoic period. Therefore, the difference between the Ningyuan Mesozoic lithospheric mantle and the Cenozoic NCC lithospheric mantle probably reflects the temporal evolution of water content in the lithospheric mantle of eastern China.

Abstract:The eastern Tanggula Range in the hinterland of the Qinghai-Tibet plateau constitutes the key to the reconstruction of the eastern palaeo-Tethys tectonic framework. It paleogeographically belongs to the eastern margin of northern Qiangtang basin, lies in the western part of the Sanjiang tectonic belt and is adjacent to the Emeishan Large Igneous Province. Volcanic rocks are widely distributed in the eastern Tanggula Range, with the volcanic activity taking place mainly in Middle Permian. Based on field mapping, the authors divided the volcanic rocks in Moyan area into three basic rock units, namely 2nd, 3rd and 4th rock unit, with the 3rd unit occurring in the interlayer form. They are in conformable contact with fine clastic rocks, mudstone and bioclastic limestone of the shallow-sea facies, making up three cycles of sedimentary-volcanic rocks in the Middle Permian Gadikao Formation. A systematical analysis of major and trace element compositions and whole-rock isotopes of the Gadikao Formation volcanic rocks indicates that the volcanic rocks belong to basalt (i.e., Moyun basalts) in the petrologic and geochemical indicators, with the rock types comprising grayish green massive basalt，grayish green massive olivine basalt and thick dark grayish green dolerite. The Moyun basalts have low and insignificantly varying SiO2, Al2O3, MgO, Ni and Cr content, being 44.24%～49.62% (averagely 45.62%), 12.27%～15.35%, 5.88%～7.52%, 112×10-6～191×10-6 and 141×10-6～269×10-6, respectively; K2O content varies remarkably (0.02%～1.27%), Mg# ratios are low (0.39～0.48), and there are high Na2O (2.36%～5.26%), TiO2 (2.12%～5.73%), total FeO (TFeO＞10%) and P2O5(0.70%～1.87%), suggesting that the Moyun basalts are similar to Emeishan continental flood basalts with high TiO2 and low Al2O3 content.As for geochemical characteristics, the Moyun basalts are of the transitional basalt series. The chondrite-normalized REE patterns indicate that all the samples have extremely high total content of rare earth elements (∑REE=284.02×10-6～678.88×10-6) and are significantly enriched in light REE (LREE), with (La/Yb)N of 14.89～23.23, (Gd/Yb)N of 2.30～3.58, and weakly Eu negative anomalies whose δEu values are 0.76～0.99.The large ion lithophile elements (LILE) (Ba, Th, Pb) and high field strength elements (HFSE) (Nb, Ta, Zr, Hf, P, Ti) in the basalts have been strongly concentrated. In the primitive mantle-normalized pattern, all the samples show weak negative anomalies of Nb-Ta, Zr-Hf, obvious negative anomalies of K, Sr and prominent positive anomalies of Th, La and Sm Rb/Sr, Zr/Ba, Ta/Hf, Nb/Zr and Th/Ta ratios are mostly in the range of 0.001～0.012 (averagely 0.006), 0.71～4.65, 0.22～0.56(averagely 0.36), 0.2～0.3 and 3.35～16.93, respectively The age-corrected initial (87Sr/86Sr)i ratios are low and vary narrowly from 0.703 3 to 0.703 9,143Nd/144Nd ratios are high (0.512 711～0.512 713), and εNd (t) values are +4.2 (t=271 Ma ). These data indicate an insignificant crustal contamination. In the diagrams of (87Sr/86Sr)i－εNd(t) for basalts, the data are fallen in the depleted mantle (DMM) area. It is thus concluded that the Moyun basalts are geochemically similar to intraplate basalts, characterized by both DMM and enriched mantle (EMⅠ). The basaltic magma might have been derived from lower degree partial melting of a garnet-bearing peridotite lithospheric mantle. The characteristics of the Moyun basalts reveal that their formation was closely related to the mantle-plume activity. The basalts must have been formed in an intraplate spreading zone (incipient rift) and have characteristics of the active rift. The data presented in this paper are of great significance for the study of the mantle evolution of the eastern Tethys in the Permian period.

Abstract:High-pressure granulite occurs as lenses in muscovite schist, granitic gneiss and amphibolite of Dulan area at the eastern end of North Qaidam HP-UHP metamorphism terrane, Northwest China. The high-pressure granulite could mainly be divided into two types: mafic granulite and acid-intermediate granulite. The dominant mafic granulite is composed of garnet, clinopyroxene, plagioclase and quartz, whereas the peak assemblage of intermediate-acid granulite is composed of garnet, plagioclase, K-feldspar, clinopyroxene, kyanite and quartz. Based on microstructure and reaction textures, the authors have recognized three main metamorphic stages from the high-pressure granulite: ① the estimated p-t conditions for the metamprphic peak stage of high-pressure granulite facies (M1) were 1.4～1.85 GPa and 800～925℃; ② retrogression began at the high amphibolite facies stage (M2) with p-t conditions of 0.8～1.05 GPa and 580～695℃； ③ subsequent retrogression occurred at the green-schist/high-amphibolite facies stage (M3). Combined with cathodoluminescence patterns and mineral inclusions（garnet, clinopyroxene and plagioclase inclusions in zircon）, U-Pb dating of zircons revealed that the peak metamorphism age of the high-pressure granulite-facies is 466.9±6.5 Ma. Petrological and chronological studies suggest that the granulite and adjacent eclogite were formed in different thermal environments of the same subduction zone, i.e., the ecolgite was formed in the subduction zone while the high-pressure granulite was formed at the root of the thickened crust above the seduction zone. The high-pressure granulite experienced its unique metamorphic history, and was not associated with the action of thermal relaxation after the eclogite-facies metamorphism recorded in adjacent eclogites.

Abstract:Major, rare earth and trace element composition of biotites from the matrix and the intra-K-feldspar phenocrysts of granodiorite porphyry and the alteration zone in the Tongshankou Cu-Mo deposit was measured by the electron probemicro-analyzer (EPMA) and the laser ablation inductively coupled plasma mass spectrometry (LA-ICP-MS). EPMA analyses of major elements suggest that biotites of different modes of occurrence differ greatly in MgO and FeOT content; however, their Al2O3,TiO2,SiO2,Na2O and K2O values do not show remarkable differences. LA-ICP-MS analyses of trace elements demonstrate that biotite is an important carrier of Rb,Ba, Nb, Ta, Sc, V, Co, Ni and Cr in granodioritic melts but has less capability in hosting U, Th, Pb, Sr, Zr, Hf and Y, and thus the concentrations of these elements in biotite are much lower than those in host rocks. Post-magmatic hydrothermal process has insignificant effects on the high field strength elements such as Nb and Ta. LA-ICP-MS analyses of rare earth elements (REE) suggest that the biotites display quite low REE concentrations (∑REE=0.150×10-6～3.691×10-6), and many of the values are even lower than the detection limits. Although there are still some differences between the three types of biotites, these differences fail to accurately reflect the differentiation degree of REE during the post-magmatic hydrothermal process. So biotite is not the main mineral phase affecting the REE features of the host rocks. Geochemical features of the three types of biotites from the Tongshankou Cu-Mo deposit are similar to those of magmatic biotites: Ti=0.38～0.45 and Mg/(Mg+Fe)=0.53～0.72. Based on the geochemical features, it is suggested that the formation of Tongshankou granodiorite porphyry was related to mantle-derived magmatism and slab subduction. LA-ICP-MS analytical results of Cu in biotites from Tongshankou granodiorite porphyry are low: the highest value is only 8.442×10-6, and many of the Cu values are lower than 2.121×10-6. So the Cu content of biotites from the intrusive rocks is not an effective indicator of mineralization. High oxygen fugacity (log fO2> NiNiO+1) in the ore-forming system seems to be favorable for mineralization of porphyry copper deposits. Based on a comparison of MgO and FeO values of biotites from different types of mineralized porphyry, it is evident that biotites associated with Cu mineralization are characterized by high content of MgO and low content of FeO. On the contrary, biotites associated with Sn mineralization are characterized by high content of FeO and low content of MgO.

Abstract:Field geological survey shows that there are many eclogite lenses outcropped in the Altun Mountains Rock Group which extends for 300 km from the Qiemo River in the west to Mangya in Altun area. Eclogite can be divided into two types according to its modes of occurrence and petrologic characteristics. One is characterized by medium-fine grained texture, massive structure, no gneissosity, weak retrogressive metamorphism, and a close relation to gneissic granite or granodiorite; mineral assembly of the early period is garnet + omphacite + quartz, and that of the late period is amphibole (or pyroxene) + plagioclase + quartz; omphacite has remarkably different Al2O3 and FeO content, while its CaO, MgO and Na2O content is relatively stable: Al2O3 is generally 5.55%～9.50%, FeO 4.33%～7.53%, and NaO 3.05%～5.54％; jadeite content is 15.39～27.49％ with an average of 22.22%; the end member compositions of pyroxene are between those of kyanite eclogite and gneiss eclogite; Chemical composition of garnet varies a lot with ∑FeO 18.82%～30.58%, MgO 2.38%～13.67%, and CaO 4.65%～10.26%, while SiO2 and Al2O3 change insignificantly, being 35.63%～39.57% and 20.92%～23.65% respectively; the average end member composition of eclogite (mostly being Mg- and Ca-rich almandine) is assigned to C type eclogite in Coleman's classification diagram (1965). The other is characterized by fine-grained texture, gneissic structure, penetrative geissosity, and obvious retrogressive metamorphism, with its wall rocks mostly related to marble, biotite granulite, quartz schist etc; a majority of this type of eclogite has been changed into garnet amphibolites with obvious retrogressive metamorphism; the eclogite is confined to Palaeoproterozoic Altun Mountains Rock Group and is comparable to the eclogite on the nortern margin of Qaidam Basin in the aspect of either wall rock characteristics or eclogite property, suggesting similar geneses; moreover, granitic gneisses as the wall rocks of eclogite have basically the same diagenetic age［（930±42）～（686±20） Ma］ and metamorphic ages［（525±31）～（434±29） Ma］as the eclogite. These similarities show that these two types of eclogite were both formed in Early Paleozoic by deep subduction of Late Proterozoic crust materials. The eclogite-bearing Altun structural complex belt is the westward extending part of the northern Qaidam Basin collision complex belt.

Abstract:The Dadonggou lead-zinc ore deposit is one of the massive sulfide deposits in the Devonian Kelan volcanic-sedimentary basin on the southern margin of the Altay Mountains. Controlled by regional Abagong-Kurti fault, the ore bodies occur in layers in the second lithologic unit of Upper Kangbutiebao Formation which consists of calcareous sandstones，biotite schists and chlorite schists．The ore minerals are sphalerite, galena and pyrite assuming massive, disseminated, banded and veinlet forms. During the regional tectonic-hydrothermal metamorphism of Carboniferous-Permian orogeny, this ore deposit experienced hydrothermal transformation, resulting in the development of veinlike quartz and mineralization. Two metallogenic stages can be identified: the first was the marine volcanic sedimentary stage, and the second was the metamorphic hydrothermal stage. There are two periods of quartz veins formed at the metamorphic hydrothermal stage: the earlier white-gray pyrite quartz veins (Q1) occur in layers and the late polymetallic sulfide quartz veins (Q2) cut the strata. By means of lithofacies observation and microthermometry, the authors carried out a detailed study of the fluid inclusions hosted by the quartz veins of the metamorphic hydrothermal stage. Combined with the preliminary findings, the authors estimated the physical and chemical conditions. Laser Raman and synchronic radiation X-ray fluorescence（SRXRF）were also used to analyze elements in the fluid inclusions. It is shown that the inclusions in the quartz veins are mainly carbonic fluid inclusions (CO2-N2±CH4) 4～37 μm in size, mostly assuming planar and ribbon distribution. There are also minor amounts of H2O-CO2 fluid inclusions associated with carbonic fluid inclusions. The experiment results of carbonic fluid inclusions show that tm,co2(solid CO2 melting temperatures) are -82.5～ -59.4℃, th, co2 (homogenization temperatures) are -40.2 ～20.3℃, and the lowest trapping temperatures are 209～459℃, that the densities range from 0.75 to 1.15 g/cm3, and that the estimated pressures are concentrated in the range of 110～540 MPa. The tests indicate that the gas and liquid ingredients in carbonic fluid inclusions mainly consist of CO2 and N2, and the minor elements are low in Cu, Zn, Pb but rich in Au. The environment for the formation of the carbonic fluid inclusions was basically consistent with the regional conditions of the orogenic belt, especially the biotite metamorphic belt. The tentative research suggests that the carbonic fluid inclusions were probably related to synorogenic metamorphism but had nothing to do with the submarine exhalation. The carbonates widely distributed in Lower Devonian Kangbutiebao Formation in the Kelan basin might have provided the main carbon sources for carbonic fluid inclusions.

Abstract:The term “molar tooth" (MT) was used by Baueman in 1885 to describe a special sedimentary structure which was first found in carbonates of Belt Supergroup, North America. Since then, geologists all over the world have conducted researches in this aspect by means of physics, chemistry and biology, with many genetic hypotheses put forward. In regard to morphology of MT, scientists has paid much attention to the relationship between lithology, morphology, environment and micro-fabrics rather than described lithology, morphology and environment simply. They have also shown concern about the problem whether different morphologies can reflect different original depositional environments or not. Exemplified by MT from Neoproterozoic Xingmincun Formation of Jinshitan in Dalian, this paper studied its morphological characteristics and analyzed its indication significance for sedimentary environment. A series of MT with complicated morphologies are developed in limestone of Upper Xingmingcun Formation. On the basis of a detailed observation, molar teeth are divided into ribbon, short-straight bar, worm, filamentous, dotted and detritusforms, with the ribbon form being dominant. The ribbon form molar teeth are subdivided into straight ribbon, bended ribbon, broken ribbon and spinous ribbon according to the difference in width, sinuosity and degree of crushing. As for sedimentary structures, there exist graded bedding, parallel bedding, horizontal bedding, stylolite and erosion surface in limestone. Some sedimentary rhythms composed of silt-carbonates, micrite-carbonates, laminated carbonates and mud-carbonates were identified, such as cycles of micrite-carbonates and laminated carbonates and cycles of silt-carbonates and laminated carbonates, which represent subtidal-intertidal cycles with upward abating sedimentary dynamics and upward shallowing water. In other words, molar teeth were formed in the lower part of shallow subtidal-intertidal microfacies, in an environment with a certain water depth and frequently fluctuating hydrodynamic force. Furthermore, the morphology of MT was constrained by the characteristics of host rocks. It is thus concluded that different sets of morphology represent different lithofacies or rhythmic units, showing the indication significance for the morphology of MT.This study partly reflects the relationship between morphology and depositional environment of MT in the whole Precambrian. With further researches, the opinion and method held by the authors could be used to study different formations in different areas, and a relationship model between morphology and depositional environment of MT can be established, which will also contribute to the researches on the genesis of MT.

Abstract:The Ordovician strata in Keping area of Tarim Basin are dominated by a series of stable carbonate and clastic rocks and can be divided into shallow platform and deep water depositional systems and then subdivided into four different facies types, namely, restricted platform, open platform, neritic shelf and basin. Based on detailed outcrop geological research, the authors found two different kinds of sequence boundaries, i.e., partially exposed unconformity sequence surface and drowned unconformity sequence surface. The partially exposed unconformity sequence surfaces are mainly developed in Lower Ordovician Penglaiba Formation and Yingshan Formation. In this period, shallow-water carbonate platform was mainly developed in the study area, and small-scale sea-level fall could result in partial exposure and erosion, thus forming sedimentary discontinuity surface. As for the causes, such partially exposed unconformity sequence surfaces belong to Type Ⅱ sequence boundary. Drowned unconformity sequence surfaces were mainly developed in Middle-Upper Ordovician, and there were mainly developed two types of surfaces in the study area, i.e., platform drowned and neritic shelf drowned unconformity sequence surfaces. Based on the above study, the authors divided the Ordovician strata into 9 thirdgrade sequences according to an analysis of the sequence stratigraphic framework. Among them, the Penglaiba Formation is comparable with two third-grade sequences, the Yingshan Formation is also comparable with two third-grade sequences, the Dawangou Formation is comparable with one third-grade sequence, the Saergan and Kanling Formations are also comparable with one third-grade sequence, the Qilang Formation is comparable with two third-grade sequences, and the Yingan Formation is comparable with one third-grade sequence. The average age of the third-grade sequence is 3.67 Ma, which constituted nine times of obvious rise and fall of the sea-level. C isotopic and element geochemical compositions of those sequences suggest that δ13C values and element geochemical compositions show obvious differences and regular variations in different sequence boundaries and different sequence system tracts. The δ13C values in the sequence interface are on the whole low. In the Internal sequence, the δ13C values change from low to high and then to low again, ranging from the transgressive system tract to the highstand system tract, and the C isotope values reach the maximum within the maximum flooding surface. It is suggested that the rise and fall of sea-level occurred many times. In the study area, element geochemical features and sedimentary sequences have a good response relationship. Invariable elements and trace elements are both low in the phase region of shallow water. With the deepening of the water, Fe, Mn, Sr and Ba values show a rising trend. In the phase region of deep water, the response characteristics of element geochemical features and the sedimentary sequences are obvious. As a result, C isotope and element geochemistry can provide some quantitative geological and geochemical evidence for analyzing the Ordovician sequence.

Abstract:Oncolite is a kind of algae pack tablets composed of two parts, the core and cladding. It was the mucus secretion during the growth of algae in the process of capturing bonded debris materials and calcium carbonate particles and was formed through the core accretion as concentric patterned grains. On October 24, 2008, the authors found oncolites in Lower Cretaceous Naijiahe Formation of Liupanshan Group in a tunnel of Sikouzi Reservoir in the Liupan Mountain. The Lower Cretaceous strata in the study area are mainly composed of a set of purple, grayish green and gray mudstone, gray marl and light yellow muddy siltstone, with thin layered plaster between the marl. Oncolites occur in the upper part of Naijiahe Formation. A study of their external core and lamination characteristics suggests that they were formed mainly in a turbulent and high-energy water-environment. Geochemical compositions of the oncolites show that the debris was derived from land-based oxides such as SiO2, Al2O3, Fe2O3, and FeO, whose values are all relatively low, with SiO2 being 8.20%, Al2O3 being 2.77%, and (Fe2O3+FeO) being 3.00%. The content of these oxides in the lake depends on the amount of terrestrial detritus that entered the lake. In addition, the inflow of terrigenous detritus and vegetation cover are also related to the extent of weathering. The lower the degree of weathering or the better the covering, the lower the debris substance content. Therefore, the oncolites with relatively low SiO2, Al2O3, Fe2O3, and FeO values indicate that during the same period the climate was relatively dry and the weathering was not strong. As only a small amount of clastic materials flowed into the lake and the lake water was relatively clean, a suitable water environment for the growth of algae and concolites were formed, and this also implies the close relationship between the influx of terrigenous clastic rocks and the growth of concolites. CaO content of concolites reaches 48.18%, indicating an obvious effects of the capturing and adhesion of calcium carbonate particles. Calcified algae itself and in situ precipitation of micro-organisms might also have been the causes for the formation of these concolites. The Sr/Ba value is 4.87, and the CaO content reaches 48.18%, suggesting that in the study area concolites were formed in a high salinity, high temperature, hot and strong evaporation arid environment. In Early Cretaceous, the region was affected by the Yanshanian movement, resulting in crustal uplift and lake atrophy. A study of the formation environment of these oncolites in Liupanshan area shows that their formation environment was consistent with the tectonic setting at that time.

Abstract:The lacustrine dolostone of Nenjiang Formation in Well CCSD-SK was taken as the study object in this paper. Well CCSD-SK is located in Qijia-Gulong depression of Songliao Basin, northeastern China, with its administration district belonging to Daqing City, Heilongjiang Province. Well CCSD-SK is the first scientific continental drilling well which mainly includes Cretaceous strata and is composed of double drilling holes located respectively in the south and the north. Lacustrine dolostone of Upper Cretaceous Nenjiang Formation has aroused much interest among geologists because it is not only a special terrane but also one of the most important oil-producing layers in Songliao Basin. Therefore, samples for this study were mainly collected from 1st Member of Nenjiang Formation in the south drilling hole. Lacustrine dolostone of Nenjing Formation has its special formation positions and shapes (mainly in layered form and subordinately in elliptic form), and layers of dolostone are interbedded with layers of mud rock, with oil shale at the bottom. Lots of Ostracoda and spinicaudatans are existent in dolostone, and a small amount of pyrite occurs in the mud rock. All this suggests a reduction environment with flourishing living things. It is thought that the formation of dolomite probably had an active effect on oil accumulation. The study of the mineralogical characteristics and the formation mechanism of lacastrine dolostone in Nenjiang Formation is hence of great significance in sedimentology. Using XRD and EPMA methods, the authors analyzed and studied mineralogical characteristics of dolostone samples. XRD results show that dolomite is the main mineral phase, quartz possesses the second position, and other minerals are small amounts of illite-smectite mixed layer, kaolinite, plagioclase, pyrite and calcite. EPMA shows that the main chemical compositions are CaO and MgO, which make up 39.778%～50.429%, and FeO and SiO2 possess the second position. Combined with XRD phase analysis, it is held that SiO2 is derived from quartz, whereas CaO, MgO and FeO come from the main mineral dolomite. The main mineral in the samples should be named ferruginous dolomite rather than ankerite because the content of MgO is much higher than FeO. This naming is consistent with the strict definition of mineralogy. The authors consider that the main mineral is ferruginous dolomite belonging to the transitional species between dolomite and ankerite rather than ankerite considered by previous researchers. The XRD results of refined parameters for the crystal unit cell also show that the samples are of the rhomb-centered hexagonal crystal having space group of R3, the parameters of a, c, V values are larger than those of the standard dolomite and much closer to those of the standard ankerite, implying that the samples and the standard ankerite have the same crystal structure; however, there exists difference in the amount of Fe2+ and Mg2+ at the same structural position, and the value arising of axis and volume results from Fe2+ substitution of part of Mg2+ in the crystal structure. It is thus thought that ferruginous dolomite is a transitional species between dolomite and ankerite in the light of crystal structure. The authors also calculated the values of the ordered degree and the mole content of CaCO3 on the basis of XRD data, and reached the conclusion that the samples having characteristics of relatively high calcium content (55.48 g/mol on average) and low ordered degree (0.40 on average) were formed in an unstable diagenetic environment characterized by rapid crystallization.

Abstract:Qingtian Stone from Qiantian County of Zhejiang Province is one of the famous “four seal stones" in China. Using such means as thin-section analysis, XRD and SEM/EDX, the authors systematically studied chemical composition and mineral composition of some typical species of Qingtian Stone. Some conclusions have been reached: ① Minerals of the selected samples are mainly composed of microscaly aggregates. ② Four types of Qingtian Stones, namely Fengmenhuang, Huangjinyao, Dengguangdong and Honghuadong, are almost exclusively composed of pyrophyllite, with Honghuadong stone also containing a small amount of ilmenite. ③ Fengmenhei and Zitandong stones are mainly comprised of pyrophyllite and sericite; in addition, Fengmenhei stone also contains a small amount of ilmenite, whereas Zitandong stone also contains hematite. ④ Lanxing, Zhuyoudong and Jiangyoudong stones are composed of pyrophyllite and illite, with Lanxing stone also containing a little illite and cryptocrystalline quartz, and Zhuyoudong stone also containing hematite. ⑤ Zhenzhudong stone is almost exclusively composed of andalusite and pyrophyllite. ⑥ Shanpaolü stone is mainly made up of sericite.