Abstract:The Fucheng composite pluton is exposed in an area of about 850 km2 and intruded into Sinian Cambrian strata with a distinctive thermometamorphic aureole of hornstone. The first stage major phase granite is coarse-medium-grained porphyritic biotite granite, whose major minerals are quartz, K-feldspars, plagioclase and lesser biotite and muscovite, and whose accessory minerals are zircon, apatite, topaz, tourmaline etc. The second stage additional phase granite is medium-fine-grained two-mica granite in the form of a small stock, whose major rock-forming minerals are quartz, K-feldspars, plagioclase, muscovite and biotite. As for petrochemistry, the indices of alumina saturation ［ACNK=Al2O3/(CaO+Na2O+K2O)］ of Fucheng pluton are higher than 1.0 (ACNK=1.22 on average), indicating that the Fucheng pluton belongs to strongly peraluminous granite. The whole rock Rb-Sr isochron ages of the first main-stage granite are 226～203 Ma, whereas the zircon U-Pb ages are 231～239 Ma, implying that the granite is an intrusive product of late Indosinian magmatic cycle. Based on microscopic observation and electron microprobe analyses, the authors recognized three kinds of muscovites, namely primary, metasomatic and secondary muscovites, in the Fucheng strongly peraluminous granite pluton, and their average crystallochemical formulas are respectively as follows: K1.62Na0.06Fe0.32Mg0.39Ti0.02Al4.89Si6.54O10(OH)4 (primary muscovite), K1.55Na0.07Fe0.43Mg0.24Ti0.03Al4.96Si6.50O10(OH)4 (metasomatic muscovite), K1.51Na0.07Fe0.27Mg0.21Ti0.00Al4.98Si6.65O10(OH)4 (secondary muscovite). According to the crystallizing sequence of main rock-forming minerals (plagioclase→K-feldspar→biotite→muscovite→quartz) in combination with an analysis of muscovite and biotite stability curves and syntectic granite solidus, it is considered that the metasomatic muscovite was formed by the replacement of early crystallized biotite in the crystallization process of the granite melt. Moreover, as uhe crystallization temperature of the muscovite was higher than the sollidus temperature of the granite melt (about 650℃), it is concluded that the metasomatic muscovite belongs to primary muscovite. A synthetic method for the discrimination between primary and secondary muscovites based on macroscopic petrological and petrochemical characteristics as well as micro-petrographic features is suggested in this paper.

Abstract:Tourmaline is a kind of accessory mineral widely distributed in acidic igneous rocks and metasomatites, and the most widely distributed Fe-Mg-Li tourmaline includes several end members like dravite, schorl and elbaite as well as a series of transitional minerals. In the same area, the same rock is often characterized by the development of the same type of tourmaline. Nevertheless, the end members and transitional minerals are well developed in Nanping pegmatite and altered wall rocks, except for elbaite. Such a phenomenon is very rarely observed in the same type of granitic pegmatites both in China and abroad. In Nanping, tourmalines with different components are distributed in different types of granitic pegmatites and different differentiation evolution stage of the pegmatite. The schorl (Fe tourmaline) is widely distributed in the four types of pegmatites as well as their altered wall rocks. In the rare metal mineralized pegmatite, the tourmaline can be divided into two types, i.e., the middle member of the Fe-Li series (Li-Fe tourmaline) and the members of the Mg-Fe series comprising dravite and Mg-Fe tourmaline. The two types of tourmalines are apparently different in the formation age and the paragenetic association of minerals. Based on detailed descriptions of physical-optical characteristics, chemical components, X-ray powder diffractions, infrared absorption spectra and thermal spectra of tourmalines from Nanping pegmatites, this paper discusses the evolution regularity and formation environment of these tourmalines. The schorl in Type Ⅰ pegmatite was formed under the conditions of upper hydraulic pressure, low content of rare elements and absolute domination of crystallization. In contrast, the schorl in Type Ⅱ-Ⅲ pegmatites was formed in a relatively low depth suggesting the beginning of the transformation to the open system, with rare elements concentrated in the pegmatite melt-solution in such an environment. The Li-Fe tourmaline in TypeⅣ pegmatite was formed in a relatively open system with wide metasomatism, with its formation depth apparently shallower than that of Type Ⅰ-Ⅲ pegmatites. In such a formation environment, elements such as Li, Rb, Cs, Nb, Ta and Sn are highly concentrated in the pegmatite melt-solution. The formation environment of dravite in Type Ⅳ pegmatite was no longer belonging to endogenic pegmatite mineralization, but this mineral inherited some characteristics of Li-Fe tourmalines in Type Ⅳ pegmatite in content of elements such as Li. Its modes of occurrence are very rarely seen in pegmatite areas both in China and abroad. The formation sequence of tourmalines in Nanping pegmatites and wall rocks is on the whole in order of black Fe-tourmaline→yellowish green Li-Fe tourmaline→yellowish brown Mg-Fe tourmaline→grayish blue dravite. This sequence will surely play an important indicating role in researches on the formation environment and evolution of the Nanping pegmatite .

Abstract:In four-facies peridotite, clinopyroxene (Cpx) contains abundant information concerning partial melting and mantle metasomatism due to its low melting point. Based on detailed studies of petrographic characteristics and major elements of minerals, the authors analyzed trace elements of Cpx in the peridotitic xenoliths from Jining area, Inner Mongolia. The properties and evolution of the subcontinental lithosphere mantle (SCLM) beneath Jining area in Cenozoic period have been discussed in comparison with things of lithospheric mantle (SCLM) beneath Hebi and Shanwang areas in the North China Craton. The peridotitic xenoliths from Hebi and Shanwang areas represent samples from the Archean (relict) and Phanerozoic (new accreted) mantle, respectively. The Jining peridotitic xenoliths are dominated by spinel-lherzolites. The lherzolites have mineral assemblage of olivine (42%～72%)＋orthopyroxene (12%～50%)＋clinopyroxene (5%～20%)＋spinel (<5%). Compared with Hebi (coarse-grained) and Shanwang (fine-grained) peridotites，Jining peridotitic xenoliths mainly display the transitional porphyroclastic texture. The olivine Mg# values of Jining peridotitic xenoliths range from 89.4 to 91.4, quite consistent with the data obtained by previous researchers, and are fairly close to the values of peridotitic xenoliths from Shanwang and Yangyuan xenoliths. The samples were collected from a fertile lithospheric mantle.The Jining SCLM was formed from the relics after low partial melting of the primitive mantle. Most of the samples have a partial melting degree of 5%～10% with only a few lower than 5%. The Jining SCLM has undergone silicate melt/fluid metasomatism, quite similar to things experienced by Shanwang SCLM. The relationship between the Ol-Mg# and the equilibrium temperature of the peridotites suggests the coexistence of fertile mantle and refractory-transitional mantle beneath the study area in Cenozoic period. Such phenomena might be attributed to the reformation of the cratonic SCLM by the upwelling asthenospheric materials and the eventual replacement resulting from the cooling of the upwelled asthenosphere under heterogeneous conditions.

Abstract:The northern margin of Alxa block is located at the juncture of North China plate，Tarim plate，Siberia plate and its southern marginal fold belt，and Alxa block．The pre-Mesozoic sedimentary formation in the study area，affected by structural positions and volcanic activities，show a great difference in different structural locations. Influenced by subsequent tectonic alternations，the strata，outcropped in the form of tectonic slices，should belong to the limited Smith stratigraphy or the transition between the limited Smith stratigraphy and Non-Smith stratigraphy，with characteristics of internal disordered state and local ordered state. This not only hinders the confirmation of the age of the blocks and the establishment of the normal stratigraphic sequence but also restricts the understanding of the tectonic and paleogeogrphic evolutions．The authors applied the ICP-MS technology and collected sandstone samples in the Lower Member of the previously-defined Amushan Formation in Wulanaobao on the eastern margin of the study area to carry out the study of U-Pb chronology．70 valid data were obtained from 80 measuring points with 79 zircons，with a range of surface ages from 259±5 to 2623±41 Ma. These surface ages are characterized by multi-peak values，with a dominant peak between 259～308 Ma（47 data）and some smaller spikes at 401～444 Ma（12 data），1652～1750 Ma（7 data）and 2601～2623 Ma（2 data）．In addition，there are two detrital zircons with ages of 731 Ma and 1237 Ma respectively．According to petrology，CL image and U-Pb chronology of the studied samples in combination with sedimentology and regional tectonic evolution， the authors have come to the following preliminary conclusions： (1) The previously-defined Lower Member of Amushan Formation along the Wulanaobao section should not be assigned to Late Carboniferous-Early Permian Amushan Formation，and the previously-defined Amushan Formation along the Wulanaobao section should be disintegrated into two parts: the middle and upper member (the upper and lower member after revision) should be assigned to Amushan Formation，which is characterized by interbedded clastic rocks and carbonate rocks and the existence of Late Carboniferous-Early Permian fusulinida fossils，such as Triticites sp. and Quasifusulina sp．；the lower member of this section is characterized by coarse clastic rocks of continental molasse formation and should be assigned to Upper Triassic，regionally comparable with Shanhujing Formation in the west of the study area and Beishan area of Gansu； (2) The tectonic style of the overthrusting of Amushan Formation on the Upper Triassic strata is probably the reflection of the thrust nappe structure in the middle and western part of Inner Mongolia and Beishan area of Gansu Province；(3) The sedimentary paleogeographic evolution shows that the provenance of the sampled sandstone could only be geological bodies of surrounding areas，because the paleogeography in and after Mesozoic was characterized by inland faulted lake basin. The zircon CL image and the ratio of 232Th/238U suggest that most of the zircons are magmatic zircons，with minor metamorphic zircons. Based on a chronologic comparison of the geological bodies in surrounding areas，this paper considers that the provenance of the sandstone should be Hercynian and Caledonian intrusive rocks，Permian volcanic rocks and pyrocalstic rocks，and Archean and Proterozoic metamorphic rocks．

Abstract:Mesozoic intermediate-acid intrusive rocks in Tongling area can be divided into two magmatic series, namely the shoshonitic series and the high-potassium (K)calc-alkaline series. The shoshonitic series is characterized by the association of pyroxene monzodiorites (PMD)+monzonites(Mz)+quartz monzonites(QM), whereas the high-potassium calc-alkaline series has the association of gabbro-diorite (GBD)+quartz monzodiorites (QMD)+granodiorites(GD). Rocks of these two series have a similar mineral association composed of feldspar, pyroxene, hornblende, biotite, potassium feldspar and quartz, but the content of these minerals is different. The cumulate enclaves such as pyroxene cumulate, hornblende cumulate and hornblende gabbro in the shoshonitic series rocks are composed mainly of pyroxene and hornblende and subordinately of spinel, feldspar, apatite and phlogopite, while micro-diorite enclaves, mafic quartz monzodiorite enclaves and mica-enriched enclaves in the high-potassium calc-alkaline series are mainly comprised of feldspar, hornblende and biotite. Taking into account the preconditions for the application of thermobarometry, the authors calculated the pressure and temperature conditions for the formation of the intrusive rocks and enclaves. The calculated results of all enclaves and intrusive rocks show that their average temperatures and pressures are 1357℃ and 1783 GPa for pyroxene cumulate, 1228℃ and 1.430 GPa for hornblende cumulate, 1214℃ and 1.300 GPa for hornblende gabbro cumulate, 889℃ and 0.413 GPa for micro-diorite enclave, 887℃ and 0.114 GPa for mafic quartz monzodiorite enclaves, 1096～1043℃ and 0.167～0.115 GPa for shoshonitic series, and 844～784℃ and 0.211～0.193 GPa for high-potassium (K) calc-alkaline series, respectively. If these pressure values are converted into the depth according to 3.3 kbar/km, their corresponding depths are 45～65 km for all cumulate enclaves, 12～15 km for micro-diorite enclaves and about 4 km for mafic quartz monzodiorite enclaves, 4～6 km for shoshonitic series and 6～7 km for high-potassium(K) calc-alkaline series, respectively. Combined with petrologic and geochemical studies of all enclaves and two series of intrusive rocks, the authors believe that all cumulate enclaves were derived from crystallization differentiation of the mafic magma in the deep magma chamber, the micro-diorite enclaves came from the mixing between evolved magma from the deep magma chamber and crustal partial melt in the shallow magma chamber, the mafic quartz monzodiorite enclaves might have been the marginal facies of early intrusive body, and the mica-enriched enclaves were probably relics of crustal partial melting.

Abstract:The study area is located in the northeast of the North China Craton and geographically belongs to the middle and northern Yanshan area. In this area,Mesoproterozoic and Neoproterozoic strata are well developed and constitute the type section of Mesoproterozoic and Neoproterozoic strata in China. Over ten thousand meters of Mesoproterozoic and Neoproterozoic strata recorded paleogeography and paleoenvironment, paleo_ocean geochemistry and the history of life development and sedimentary evolution. The Kuancheng area of northern Hebei has great thickness of Mesoproterozoic and Neoproterozoic sediments, with ideal outcrops. Previous researchers had conducted fairly detailed investigation in this area. Geochemical studies of Mesoproterozoic and Neoproterozoic strata in Jixian County started in the late 1970's, with the emphasis placed on major elements. In the middle of the 1980's, Liu Baoquan et al. (1985) carried out organic geochemical researches on Mesoproterozoic, Neoproterozoic and Lower Paleozoic carbonate rocks in North China. Wang Songshan et al. obtained an age of dark banded chert (1317 Ma) at the top of Yangzhuang Fomration. The multiple stratigraphic division method was also introduced into the division and correlation of Mesoproterozoic and Neoproterozoic strata.The Yangzhuang formation has a total thickness of 322.37 m and consists mainly of carbonate rocks which include micritic dolomite, sand-bearing micritic dolomite and chert striped dolomite as well as local corrugated stromatolite dolomite, arenaceous dolomite and gravel lithic silicalite. In these rocks, horizontal laminae and birdeye structures are widespread. In order to analyze the influence of geochemical characteristics of carbonate rocks on stratigraphic and sequence boundaries as well as sedimentary environment, the authors chose the geological section of Mesoproterozoic Yangzhuang Formation in Kuancheng to conduct in-situ measurement. Along this section, there exists obvious vertical characteristic evolutionary regularity of major and trace elements as well as carbon and oxygen isotopes, which is especially obvious near stratigraphic and sequence boundaries. CaO content is 21.07%～16.45% from 1st Member to 2nd Member of Yangzhuang Formation, and is 16.45%～24.21% from 2nd Member to 3rd Member. From the bottom of Yangzhuang Formation upward, Sr changes abruptly from 44.59 μg/g to 98.16 μg/g and Ba from 0.51 μg/g to 10.45 μg/g, whereas δ13C and δ18O vary in the ranges of 0 ‰ to -1.5‰ and -3.5‰ to -8.5‰, respectively. The variations of the above data were basically consistent with the sea level variation of the same period, suggesting that geochemical characteristics can serve as indicators for dividing stratigraphic or sequence boundaries and, especially, for optimizing these boundaries. δ18O values of carbonate rocks formed in the same sedimentary and diagenetic environment are closely related to the physical-chemical conditions of the sedimentation period and, especially, to the climatic variation. It is generally held that in the glaciation period, temperature dropped, salinity rose, and some light oxygen isotopes were trapped in the glacial sheet, causing the relative increase of δ18O values in the sea water, whereas in the temperature-rising period, glacial sheet was melted, salinity decreased, and large quantities of light oxygen isotopes were released, which would result in the relative increase of the δ18O values in the sea water. Carbon and oxygen isotopic data in this paper demonstrate that, although there exists a slight positive bias in 2nd Member of Yangzhuang Formation, C isotopes generally show a relatively stable variation and have negative values, varying in the range of -0.55 ‰ to -1.28 ‰. Oxygen isotopes vary in the range of -8.17‰ to -3.47‰, generally assuming an obvious positive bias trend.The considerable vertical fluctuation of major and trace elements in Yangzhuang Formation of this area indicates brisk tectonic activities of the Yanshan aulacogen in this period, which led to the remarkable variation of sedimentary environment. Oxygen isotope analyses suggest that the paleoclimate was basically in a sedimentary environment of supralittoral zone with relatively high temperature. Major and trace elements at stratigraphic and sequence boundaries change evidently, and the variations of carbon and oxygen isotoles assume a corresponding relationship with the rise and fall of the sea level. All this suggests that geochemical characteristics can be used to joptimize stratigraphic or sequence boundaries that have already been defined.

Abstract:Lots of granitoids are distributed in Tengchong-Lianghe area, western Yunnan Province. According to data available, the ages of these granitoids are mostly concentrates in the Late Mesozoic-Cenozoic period. In this paper, ages of Late Permian-Middle Triassic peraluminous granites in this area were obtained for the first time. Granitoid bodies are distributed near southeastern Lianghe County. The major rock types include mainly grayish medium-grained two-mica granite and subordinately gray fine-grained two-mica granite in the form of bosses or dikes one to several meters in width scattered in medium-grained two-mica granite. The medium-grained two-mica granite exhibits hypidiomorphic granular texture and is mainly composed of K-feldspar (perthite，±40％), quartz （±30％）, plagioclase (oligoclase，±15％), biotite and muscovite（±15％）, with accessory minerals comprising zircon and iron oxides. The fine-grained two-mica granite exhibits hypidiomorphic granular texture too and is mainly composed of K-feldspars (perthite and microline, ±30％), quartz （±25％）, plagioclase (oligoclase, ±25％), biotite and muscovite（±20％）, with accessory minerals being zircon and magnetite. The two-mica granites have the following geochemical characteristics: SiO2＝69.74%～74.44%, Al2O3=13.91%～14.52%, MgO=0.26%～0.87%, CaO=0.72%～1.36％, K2O=5.24%～5.78%, Na2O=2.63%～2.82%, K2O/Na2O=1.87～2.20, and Al index (A/CNK)＝1.11～1.20. Moreover, corundum can be found in the CIPW norm minerals, which possesses some features of strongly peraluminous granites. The two-mica granites composed of medium-grained and fine-grained granite are characterized by the enrichment of Rb（315×10-6～452×10-6）, U（7.68×10-6～11.2×10-6）and Th（15.2×10-6～111×10-6）. Primitive mantle-normalized element concentration patterns of both granites show remarkable negative anomalies of Ba，Nb，Sr，P，Ti. Likewise, both of the granites display similar REE patterns: Eu/Eu*=0.25～0.47 and (La/Yb)N =6.53～34.06. Most of the zircons from the sample show oscillatory zoning in CL images with Th/U ratios from 0.1 to 1.8, indicative of magmatic zircon in genesis. Zircon LA-ICP-MS U-Pb dating from the same sample yielded concordant ages of 256.0 ±5.6 Ma (MSWD=4.1) and 234.2 ±3.1 Ma (MSWD=5.6), which respectively indicate the early (i.e. Late Permian) and late (i.e. Middle Triassic) magmatic episodes during the early Indosinian period in this area. An inherited zircon age（ca.596 Ma）was also obtained. In-situ Hf isotopic analyses yieldedεHf(t) values of -8.5 to +1.3, corresponding to the Hf isotopic crustal modal ages (tDMC) of 1195～1815 Ma. The geochemical signatures and zircon Hf isotopic compositions suggest that the magma of the two-mica granites was dominantly derived from partial melting of clay-rich psammite in the older crust. These two-mica granites were formed in a continental collision environment. Combined with available data, it is held that the generation of the collisional strongly-peraluminous granite in the Late Permian-Middle Triassic period suggests an orogenic event during early Indosinian in the Sanjiang Paleo-Tethys Sea. The Sanjiang early Indosinian orogenesis was intimately related to the closure of the Paleo-Tethys Sea and the subsequent orogenic events.

Abstract:Historical literature and archaeological records show that white porcelains began to appear in North China during the period of the late Northern and Southern Dynasties (386～581). Xing Kiln was one of the most famous kilns to fire white porcelains at that time, and hence products of this kiln are valuable resources for exploring the origin of the white porcelain. Nowadays, most of the experts agree that the white porcelain was derived from the celadon, and they further point out that a series of technological innovations, such as the elaborate choice and treatment of porcelain materials, the adoption of huazhuangtu, the lower firing temperature and the thinner glaze must have played an important role in the appearance of the white porcelain. As far as the recipe of the body material is concerned, however, there exists controversy among experts. Some people hold that binary recipe or multi-recipe was applied to the body material at the very beginning, while others believe that the body material must have experienced the process from mono-recipe at the beginning to binary recipe or multi-recipe with the development of the porcelain firing technology. In this study, 15 pieces of coarse white porcelains and celadons from Xing Kilns and 4 kinds of porcelain materials were collected and analyzed by means of EDXRF and INNA, and the data were processed by softwares of SPSS and origin. The results indicate that there is little difference in chemical composition between the body of the coarse white porcelain and that of the celadon. It is hence concluded that the potters of Xing Kiln adopted the same kind of material for the body material of both coarse white porcelain and celadon. In addition, the body chemical composition of white porcelains, which includes major elements and trace elements, is very similar to that of local kaolin clay characterized by relatively high Fe, Ti and low Al, suggesting that the potters probably adopted this kind of material to fire the white porcelain. This study provides an important basis for probing into the recipe of body material of the white porcelain. Nevertheless, the problems as to whether kaolin clay with higher Fe, Ti and lower Al could be used as the mono-material to fire the white porcelain and how the ancient potters distinguished the mono-recipe from the multi-recipe remain to be solved in future. In our further work, therefore, more systematic samples should be collected and analyzed, and simulative firing should also be carried out. Only in this way can these problems be solved.

Abstract:Magnetic micro-particles in soil polluted by heavy metals around 13 cities were collected for the purpose of determining their environmental significance. They can be used as tracers for the source of heavy metals in soil because the microstructure and mineral component characteristics show evidently their derivation from coal combustion. The magnetic susceptibility of falling dusts containing abundant magnetic micro-particles is much higher than the average value of urban soil, which explains clearly the reason why soil polluted by heavy metals always has high magnetic susceptibility. Finer particle sizes of magnetic micro-particles have higher magnetic susceptibilities, which facilitates the diffusion of heavy metal pollution for a long distance. The occurrence rates of the magnetic micro-particles in soil collected from 13 investigated cities all exceed 80%, which indicates the universal distribution of magnetic micro-particles in soil of urban and surrounding areas. The average content of the magnetic micro-particles in 5 kg soil sample collected from Beijing varies in the range of 30～7070 mg with the highest being 267 g. Magnetic micro-particles can be regarded as carriers of heavy metals in soil because all the eight heavy metals could be detected in chemical component analysis and the content is 2～25 times higher than the soil eco-geochemical reference value of China's eastern plain region. Results of correlation analysis show that in most cases there exists a significant correlation between content of heavy metals in magnetic micro-particles and that in soil polluted by coal combustion. The contribution rate of magnetic micro-particles to heavy metal accumulation in soil is generally lower than 1% though it could reach 10% or 60% in soil with much more magnetic micro-particles. It must be emphasized that the contribution rate mentioned above only shows the trend of the environmental effect of coal combustion because magnetic micro-particles do not constitute all the pollution components produced in the process of coal combustion and the content of magnetic particles can not be quantified due to the unavoidable loss in the process of elutriation. Nevertheless, the above phenomena could at least prove that magnetic micro-particles can be used as an easy means for connecting media that contact heavy metal pollution in soil of cities with atmosphere pollution produced by coal combustion. As heavy metals in magnetic micro-particles are commonly very inactive, the evaluation criterion range of heavy metal content in eco-geochemical assessment can be properly broadened according to the content of magnetic micro-particles in areas around coal combustion factories. At the same time, it should be taken into account that heavy metals in magnetic micro-particles can also be released in some extreme conditions such as low pH or high salt content. Forecast should be conducted so as to prevent the environmental disaster produced by activated heavy metals in magnetic micro-particles.

Abstract:In order to study the impact of the soil organic carbon content and soil organic carbon heterogeneity on the sorption behavior of trichloroethylene (TCE), the authors collected 7 soil samples including 3 surface soil samples of Beijing urban area and 4 soil standard reference samples. These 7 samples were treated by using H2O2 to remove the lower aggregate carbons (LAC). Both treated and untreated soil samples were used to carry out statistic batch tests on the TCE isotherm sorption patterns. The results show that the isotherm adsorption patterns fit the liner sorption model very well both for the treated and untreated soil samples. The removal of LAC did not change the sorption model type, and only changed the parameters of the liner formulae. The residual organic carbon content of all the samples remained higher than 0.1%, and the organic carbons still played the main role during the sorption. The results also show that there exist no apparent relationships between the soil sample sorption capabilities and different kinds of organiccarbon content, i.e., the total organic carbon (TOC) content and the higher aggregate carbon (HAC) content and LAC content， and the total sorption capabilities of 7 originalsoil samples used in these tests are mainly determined by the LAC sorption capabilities. These data have confirmed the fact that TOC, LAC and HAC all have obvious heterogeneities, i.e., the same soil organic carbon content will have different sorption capabilities. The difference in organic carbon construction and components is the key factor affecting the sorption behavior. Unless the difference in organic carbon construction and components is negligible, the organic carbon content will play an important role in affecting the TCE sorption behavior. However, the heterogeneities of soil organic carbons are mainly caused by the difference in mineralization and humification.

Abstract:Nephrite, widely distributed in nature, is one of the earliest natural jade resources developed and utilized in human history. The relatively well-known nephrite deposits in China include Hetian of Xinjiang, Xiuyan of Liaoning, Golmud of Qinghai and Hualien of Taiwan as well as some nephrite deposits discovered since the 1990's such as Xiaomeiling in Liyang of Jiangsu and Mianyang of Sichuan. Previous studies of nephrite were almost confined to the nephrite from a single producing area and were lacking in comparative work. There is also a lack of systematic research on the causes responsible for the differences in the texture of nephrites from different producing areas, which results in shoddy phenomena in the current market. Therefore, it is particularly important to seek for identifying symbols and quality appraising factors for nephrites from different producing areas. In this paper, the authors employed polarizing microscope, LA-ICP-MS and SEM analysis to study typical varieties of Xinjiang and Xiuyan nephrites. Test results show that physical properties of the nephrites from the two producing areas are similar to each other, but Xiuyan nephrite is not so good as Xinjiang nephrite in luster, transparency, and polished finish. There is almost no yellow-white jade and green jade in Xinjiang nephrite, and the yellow jade common seen in Xinjiang nephrite is on the whole not observed in Xiuyan nephrite, which accounts for the significant difference in color between the nephrites from the two areas. The content of the common coloring elements such as Be, V, Cr, Co, Ni and Cu in the two nephrite producing areas is not consistent, and there exists no corresponding relationship between the changing trend and the varieties. The total content of trace elements is the highest in green nephrite, and such elements as Be, Ni and Cu have a certain impact on the green color of nephrite. The ΣREE values of Xinjiang nephrite range from 1.4698×10-6 to 4.2217×10-6, the values of (La/Yb)N vary from 0.5663 to 10.8392 and δCe from 0.8115 to 0.9866; the ΣREE values of Xiuyan nephrite range from 5.1850×10-6 to 20.4230×10-6, the values of δCe vary from 0.8386 to 0.9885, and (La/Yb)N from 2.1071 to 5.6884. The nephrites from the two producing areas generally have low rare earth elements and clear differentiation of LREE and HREE, suggesting the enrichment of HREE. In addition, δEu are characterized by both positive and negative anomalies. The REE partition curve shows the REE features of multi-sources of ore-forming fluids and multi-period mineralization. The difference in the ore-forming source and the environment is the basic factor causing the different REE compositions of the nephrites from the two nephrite producing areas. Photomicrographs show that Xinjiang nephrite is mainly composed of fibrous, columnar, needlelike and flaky tremolite, and its impure minerals are composed of occasional limonite, ferric oxide and chlorite, illite and other clay minerals, whose content does not exceed 1%. It is colorless under polarization microscope and assumes middlepositive relief, with the relief gradually increasing with the increase of Fe content in samples. Its interference color is yellow to purple in Grade I. Xiuyan nephrite is similar to Xinjiang nephrite in mineral composition and structure, but it has larger particle sizes, poor compactness and larger gaps between the particles. The tremolite mainly has radiate fibrous and columnar shape through SEM observation, which seems to be the common character of the nephrites from the two producing areas, but Xinjiang nephrite has the most typical feltlike fiber woven blastic texture, with the particle sizes generally less than 3 μm and the lengths of columnar and fibrous particles generally less than 10 μm. Xiuyan nephrite commonly has micro-fiber and micro-leaf-shaped structure, and the tremolite grains assume leaf-shaped and fibrous distribution. The tremolite grains are thicker than those of Xinjiang nephrite, and the lengths are mostly in the range of 10～20 μm, with rather bad density. In addition, there are often uneven fractures or faults developed in the cleavage direction of tremolite in Xiuyan nephrite, which affects the quality of nephrite to a certain extent and seems to be an important factor causing the fact that its quality is not so good as that of Xinjiang nephrite.