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A natural ilmenite (PZH12-09) is homogeneous and thus suitable for use as a reference material for in situ microanalysis. An EPMA method was developed to determine the trace elements of ilmenite, with high precision and low detection limits.

High-grade hematite mineralization is widely developed in banded iron formations (BIFs) worldwide. However, in the North China craton where Neoarchean-Paleoproterozoic BIFs are abundant, economic high-grade hematite ores are scarce. High-grade hematite ores hosted in the Paleoproterozoic Yuanjiacun BIFs represent the largest occurrence of this type of ore in the North China craton. The orebodies are fault controlled and show sharp contacts with lower greenschist facies metamorphic BIFs. In situ U-Pb geochronology of monazite and xenotime intergrown with microplaty hematite and martite in high-grade ore established two episodes of metamorphic-hydrothermal monazite/xenotime growth after deposition of the BIFs. The earlier episode at ca. 1.94 Ga is interpreted as the timing of lower greenschist-facies metamorphism, and the later episode at 1.41 to 1.34 Ga represents the timing of high-grade hematite mineralization. Petrography and microthermometry of primary fluid inclusion assemblages indicate that the high-grade hematite ore formed from hot (313°–370°C), CO2-rich, and highly saline (~20 wt % NaCl equiv) hydrothermal fluids. These fluids channeled along faults, which concentrated iron through interaction with the BIFs—a process similar to typical hematite mineralization elsewhere. The deposition of hematite was probably related to tectonic extension in the North China craton related to the breakup of the Columbia/Nuna supercontinent. Our results challenge a previously proposed model ascribing the scarcity of high-grade hematite ores in the North China craton to the lack of prolonged weathering conditions. Rather, we argue that the high-grade ore formed in lower metamorphic-grade BIFs at shallower depths than magnetite mineralization and was largely eroded during later exhumation and uplift of the craton.

New age data for the Baoban Complex, South China establishes that it lay outboard of western Laurentia in the early Mesoproterozoic but was not part of the Cathaysia Block, with which it is traditional linked, until the mid-Paleozoic. Our geochronology data for detrital zircon and authigenic monazite grains from metasedimentary rocks indicate accumulation between ca. 1.55 Ga and 1.45 Ga for the Gezhencun succession of the Baoban Complex and ca. 1.45 Ga and 1.30 Ga for the Ewenling succession. The former unit is dominated by detrital zircon populations between 1900 Ma and 1500 Ma with two peaks at 1780 Ma and 1580 Ma. The Ewenling succession has detrital zircon peaks at 1720 Ma and 1450 Ma. Newly discovered gneissic granites were emplaced at 1550 Ma and intruded by 1450 Ma leucogranite dykes that are coeval with 1460–1430 Ma bimodal magmatism. The whole Baoban Complex was metamorphosed over the range of 1.3–0.9 Ga based on ages of authigenic zircon and monazite. Depositional ages of metasedimentary rocks are coeval with successions of the Belt-Purcell Basin, western Laurentia. Detrital zircon from the two regions have similar age populations and Lu-Hf compositions, and display a synchronous provenance shift at ca. 1.45 Ga. Basement lithologies on Hainan Island range in age from ca. 1.55–1.43 Ga and underwent metamorphism during 1.3–0.9 Ga. This is younger than basement rocks on the mainland of the Cathaysia Block in South China, suggesting the two regions are spatially unrelated at this time and hence the Mesoproterozoic record of the island cannot constrain the location of the Cathaysia Block in the Nuna and Rodinia supercontinents.

Although less common than hematite ores, high-grade magnetite ores represent a distinct type of iron mineralization hosted by banded iron formations (BIFs). The Gongchangling iron deposit hosted in ~2.55 Ga BIFs in the North China craton represents one of the most economically important iron deposits in China. Located in mining area II, it is a high-grade (>50 wt % Fe) magnetite deposit and one of the largest of its type in the world. However, the lack of reliable age constraints on iron mineralization has hindered the testing of competing genetic models for the formation of the Gongchangling deposit. In situ U-Pb geochronology of monazite and zircon intergrown with garnet from the proximal alteration zone of a high-grade iron orebody yielded an age of 1.86 Ga, which represents the timing of formation of high-grade magnetite mineralization. This age is coeval with a tectonic extension event recorded in the northeastern North China craton. Our results preclude the previously suggested genetic link between high-grade magnetite mineralization and ~2.50 Ga regional metamorphism. Growth of authigenic monazite and zircon is likely related to the breakdown of detrital zircon, which has undergone metamictization. In combination with previously published data, we propose that the development of zoned alteration associated with the deposit, which is characterized by the garnet-amphibole-magnetite assemblage in the proximal zone changing to a chlorite-quartz–dominated assemblage in the distal zone, can be attributed to a gradual decrease in temperature from >550° to ~250°C and to alteration minerals forming from leaching of the BIFs instead of by replacement of the wall rocks. Magnetite mineralization was controlled by the well-developed faults that cut the BIFs and provided conduits for silica-undersaturated alkaline meteoric fluids. Fluid flow likely took place in an extensional tectonic regime, similar to that invoked elsewhere for hematite mineralization but at greater depths.

Most of the Algoma-type BIFs and associated volcanic suites in the North China Craton (NCC) have undergone high-grade metamorphism during the ∼2.5 Ga tectonothermal event. Isotopic systems in high-grade metamorphic rocks are often reset, thereby losing the earlier records, whereas zircons in low-grade metamorphic rocks are potential candidates to evaluate earlier thermal events. Detailed textural relationship and internal structures of zircons and their age data for eight wall-rock samples with metamorphic grades from greenschist to upper amphibolite facies of the Algoma-type BIFs in the Anshan–Benxi area are used to constrain the age of protolith. Zircons in the greenschist to lower amphibolite facies are generally metamorphism-resistant, whereas those in the upper amphibolite facies rocks show variable recrystallization. SHRIMP zircon U–Pb dating of magmatic zircons in six samples constrains the peak of BIF-deposition at 2.56–2.53 Ga, which is consistent with ∼2.5 Ga crustal growth in the NCC. In addition, the greenschist-facies metamorphic rocks in the Anshan area also record an event of volcanic activity at 2.72–2.65 Ga. We consider that low-grade metamorphic wall rocks were not significantly affected by the ∼2.5 Ga tectonothermal event, and the 2.72–2.65 Ga age group records another important magmatic event corresponding to ∼2.7 Ga crustal growth. The metamorphic zircons from these rocks record a thermal event during 1.88–1.84 Ga.

Mafic–ultramafic intrusions comagmatic with Proterozoic massif-type anorthosites can provide insights into the parental magma from which large volumes of hyper-feldspathic rocks are produced. Recent deep drilling has unveiled a large olivine–Ti-magnetite-rich layered intrusion (named Dawusunangou) beneath the Damiao massif-type anorthosite complex in the North China Craton. The layered intrusion is composed of alternating olivine–Ti-magnetite-rich dark layers and plagioclase-rich light layers (ca. 35–80% plagioclase), with the latter also containing pod- or lens-shaped pyroxene–Ti-magnetite-rich aggregates. This layered intrusion shows low Mg# and REE patterns similar to the overlying Damiao anorthosite complex. Baddeleyite Pb–Pb geochronology yielded indistinguishable crystallization ages of ca. 1735 Ma for both the Dawusunangou layered intrusion and the Damiao anorthosite complex, suggesting coeval emplacement. Using the average bulk compositions of the two intrusions, mass balance calculations assuming 30–40% Dawusunangou and 70–60% Damiao would give a composition similar to high-Al basaltic magma. Collectively, these features indicate that the Dawusunangou layered intrusion represents the mafic residues after the segregation of the Damiao anorthosites from high-Al basaltic parental magma. A short-lived magma chamber is thought to have supplied the two intrusions. In situ crystallization with variable nucleation rates for plagioclase combined with the mafic minerals crystallizing in equilibrium proportions resulted in the formation of repeated dark and light layers of the Dawusunangou layered intrusion. The two intrusions are interpreted to have formed by multiple magma injections, instead of continuous differentiation of one melt. The parental magma was derived from a depleted mantle source with significant crustal contribution during magma evolution. The large Nd–Hf isotopic variations suggest contamination by Paleoarchean to Neoarchean crust.

The ∼1.7 Ga Damiao anorthosite complex (DAC) in the North China Craton contains abundant Ti–magnetite-dominated ore deposits. Both the Fe–Ti–P-rich silicate rocks and massive Fe–Ti–(P) ores occur as discordant late-stage dikes cross-cutting early-stage anorthosites with irregular but sharp boundaries. Field and petrographic observations indicate that some late-stage dikes are composed of unique oxide–apatite gabbronorites (OAGNs), whereas others comprise well-developed alternating late-stage anorthosites and Fe–Ti–P-rich pyroxenites defining rhythmic layers. Massive Fe–Ti–(P) ores are closely related to the Fe–Ti–P-rich pyroxenites. Plagioclase and whole-rock compositions of different rock types were analyzed to constrain the late-stage magma evolution and genesis of the Fe–Ti oxide ores. The similar mineralogical assemblages, REE and HFSE patterns suggest that the different rock types formed by differentiation from a common parental magma. Early-stage anorthosites are characterized by positive Eu anomalies and low REE contents, whereas the late-stage dike-like rocks display no significant Eu anomalies and high REE contents. Plagioclase compositions in the late-stage rocks show a decrease of An contents when compared to that of the early-stage rocks. Based on field relations, petrography and well-defined linear compositional trends, the sequence of crystallization is inferred as: early-stage anorthosites + leuconorites + norites, OAGNs, late-stage anorthosites + Fe–Ti–P-rich pyroxenites + massive Fe–Ti–(P) ores, and massive Fe–Ti–(P) ores. The OAGNs which underwent relatively rapid crystallization represent an early phase during the residual magma evolution after anorthosite separation, whereas the rhythmic layers formed by slow but extensive fractional crystallization of interstitial melt. High solubility of phosphorous played an important role in the formation of rhythmic layering. Massive Fe–Ti–(P) ores crystallized and segregated directly from the magma of Fe–Ti–P-rich pyroxenites, thus representing the most evolved products of the residual magma. Progressive and extensive fractional crystallization of residual ferrobasaltic magma is probably responsible for the formation of large-scale massive Fe–Ti–(P) ores.

Algoma-type BIFs and associated volcanic suites of the Qianxi Group in eastern Hebei Province have undergone high-grade metamorphism and anatexis. The anatectic event is genetically related to high-grade magnetite ores, but the age of the anatectic melting has not been well constrained. We present detailed textural relationship and internal structures of zircon grains and their age data from eight samples of migmatitic rocks representing the different Algoma-type BIF-hosted iron deposits to constrain the formation age of BIF deposition and subsequent anatexis. Six continuous zircon growth stages are distinguished by a series of low-CL and high-CL zones outside from center to edge: inherited magmatic zircon, bright-CL resorption domain, dark-CL recrystallization front, dark-gray-CL diffusion domain, light-gray-CL overgrowth and bright-CL resorption edge. The overgrowths are interpreted as a solid-state diffusion of Zr of primary zircon during interaction with anatectic melt, which resulted in different stages of chemical re-equilibration of primary domains and local re-deposition of newly grown domains on the suitable isostructural substrate of residual magmatic zircon. SHRIMP zircon U–Pb dating of inherited magmatic cores and discrete magmatic grains constrains the peak BIF-deposition age at 2520 Ma, which is different from the peak at 2.75–2.70 Ga for Algoma-type BIFs elsewhere in the world. Zircon U–Pb dating of light-gray-CL rims and newly grown homogeneous grains indicates that the anatectic event lasted from 2511 to 2485 Ma at least, immediately following the BIF deposition. The BIF depositional event is consistent with widespread late Neoarchean magmatism, and the anatectic event is consistent with regional metamorphic events in the eastern part of the North China Craton.

Volcanic rock-hosted iron deposits are among the important iron ores in China. However, the nature of primary magma and petrogenesis associated with these iron ores remains controversial. Here, we report iron-rich fragments (IRF) from the Yamansu iron deposit in Eastern Tianshan Mountains, NW China, which occurs in association with volcanic breccia, submarine volcanic breccia and ignimbrite. The IRF is composed of five types including oligoclase-iron oxide type (OIO), oligoclase-albite-iron oxide type (OAIO), albite-iron oxide type (AIO), albite-K-feldspar-iron oxide type (AKIO) and K-feldspar-iron oxide type (KIO). These fragments display typical volcanic fabric features, such as porphyritic texture, hyalopilitic texture of the groundmass and vesicles filled by minerals to form amygdales. The feldspar phenocrysts of IRF are dominantly albite. The groundmass of IRF consists of magnetite and feldspar. The magnetite is distributed in between the feldspar laths, and together display hyalopilitic texture which could be observed only in volcanic rocks. The vesicles are filled with magnetite, feldspar, chlorite and calcite from the margin to the interior. The IRF has high Si, Al, Fe, Ca, Ti, Na and K contents and low Mg content. The average total Fe is 26 wt.%. The magnetite is mostly titanium–vanadium magnetite, with the TiO2 content ranging up to 4.86 wt.% and V2O3 content up to 3.20 wt.%. The IRF probably came from iron-rich melts and represent the products of the Fenner magma evolution. The basaltic magma evolved into the Fe–Na-rich residual melts by crystallization under low oxygen fugacity condition in a closed magma chamber after intruding into the shallow crust. The Fe–Na-rich residual melts were emplaced in hypabyssal environments or erupted generating the orebodies or providing the material source for the generation of the high-grade iron ores which were subsequently enriched by the late-stage hydrothermal fluids.

The high-grade magnetite ores related to banded iron formations (BIFs) in the Anshan-Benxi area, Liaoning Province in China, have been widely interpreted as the product of replacement of protore by epigenetic hydrothermal fluids. The high-grade iron ore reserves in the mining area II (164 million tons) in the Gongchangling (G2) and Qidashan-Wangjiabuzi (QW) iron deposits (11.45 million tons) are the largest deposits in the Anshan-Benxi area. We present a detailed comparison of the geology, geochemical and stable isotopic compositions of the iron ores in the G2 with those in the QW to constrain the role of desilicification and iron activation–reprecipitation in converting the BIFs to high-grade magnetite ores. These two deposits show marked difference in wall-rock alteration, geochemical features, and oxygen and sulfur isotopic compositions. Wall-rock alteration in the G2 is characterized by garnetization, actinolitization, and chloritization, whereas the QW shows chloritization, biotitization and sericitization. The geochemistry of altered rocks in the G2 is characterized by slight REE fractionation, positive Eu and no significant Ce anomalies, whereas the QW is characterized by high ΣREE contents, strong REE fractionation, and the absence of significant Eu and Ce anomalies. High-grade iron ores in the G2 show similar δ 18 O V-SMOW values for magnetite, lower δ 18 O V-SMOW values for quartz and higher δ 34 S V-CDT values for pyrite when compared to the BIFs, whereas the QW shows lower δ 18 O V-SMOW values for magnetite, similar δ 18 O V-SMOW values for quartz and similar δ 34 S V-CDT values for pyrite. These features indicate that desilicification process by hypogene alkaline-rich hydrothermal fluids were possibly responsible for the formation of high-grade iron ores in the G2 whereas iron activation–reprecipitation process by migmatitic-hydrothermal fluids generated the high-grade iron orebodies in QW.

The Tieshanmiao-type iron deposits in the southern North China Craton comprise two types of ores: banded pyroxene–magnetite quartzite (BMQ) and disseminated magnetite pyroxenite (DMP). Whether the quartz-poor DMP represents metamorphosed iron-bearing ultramafic rocks or chemical sedimentary rocks is still unclear. Pyroxene compositions in the DMP are low in Al 2 O 3 and TiO 2 , which are similar to those from the BMQ and altered marble and pyroxenite. However, the compositions are different from those in the metamorphosed ultramafic rocks. The DMP and BMQ also show similar major element contents, with dominant SiO 2 , total Fe 2 O 3 , CaO, MgO but low contents of Al 2 O 3 , TiO 2 , MnO, Na 2 O, K 2 O, indicating a similar source through submarine chemical precipitation with little input from terrestrial or volcanic materials. The BMQ, DMP and magnetite separates from these rocks exhibit seawater-like signatures of REE patterns with LREE depletion, positive La, Gd and Y anomalies and high Y/Ho ratios, indicating that seawater participated in the formation of the iron ores. Combined with strong positive Eu anomalies, we infer that the deposition of the BMQ and DMP was mainly controlled by the mixing of seawater with hydrothermal fluids. The lack of negative Ce anomalies of the DMP, BMQ and magnetite separates indicate an anoxic marine environment. The DMP is rich in carbonate but relatively poor in silica and the BMQ is rich in silica but poor in carbonate. The protoliths of the DMP and BMQ in the Tieshanmiao-type iron deposits are inferred to be quartz–carbonate iron-bearing formations which underwent subsequent metamorphism.

The Damiao Fe–Ti–P deposit offers a rare opportunity for studying late-stage Fe–Ti ore-forming processes in Proterozoic anorthosites. The orebodies are hosted in anorthosite and commonly show chlorite-dominated alteration in the contact zone on both sides, but the nature and origin of fluids in Fe-Ti-P mineralization remains contentious. Baddeleyite is a common accessory mineral in anorthosites and Fe–Ti–P orebodies, and typically occurs as blebs and lamellae in primary ilmenite reflecting decreasing solubility of Zr in ilmenite during slow cooling and consequent exsolution of ZrO2. Two types of zircon are identified in the Fe–Ti–P orebodies and altered anorthosite at Damiao, and both are related to hydrothermal replacement of baddeleyite by Si-rich fluids. The type-I zircon shows subhedral to anhedral shapes with variable sizes (5–50 μm) in Fe–Ti–P orebodies, and coexists with magnetite–rutile symplectite formed by ilmenite breakdown. In contrast, the type-II zircon typically occurs as tiny aggregates in chlorite–quartz–titanite replacement fronts of altered anorthosite, indicative of a hydrothermal origin. The type-I zircon yielded an age of 1739 ± 16 Ma, similar to the age of baddeleyite previously reported for the orebodies. Formation of the type-I zircon is related to the replacement of baddeleyite in the presence of Si-enriched hydrothermal fluids evolved from magma. Ti-in-zircon geothermometry indicates a fluid temperature of >700 °C for the formation of the type-I zircon. However, homogenization temperature of fluid inclusions in co-precipitated apatite suggests that the type-II zircon in altered anorthosite may have formed by later hydrothermal fluids at temperature of ~350 °C. Our results indicate that the Fe–Ti–P mineralization of the Damiao anorthosite complex involved hydrous melts and magmatic–hydrothermal processes, with the Fe–Ti oxides being formed at the magmatic stage and apatite at the hydrothermal stage.

China has the largest global demand for iron ore resources, with more than 50% of its demand presently being met from foreign sources. Iron resources are abundant in China (ca. 80 billion tons of proven iron ores), but high-grade ores are scarce. Most iron deposits in China are low in grade, with an average grade of 30.62% TFe. The iron deposits in China are divided into six types: sedimentary–metamorphic, magmatic Fe–Ti–(V), volcanic rock-hosted, contact metasomatic–hydrothermal (mostly skarn), sedimentary, and weathering–leaching type. Sedimentary–metamorphic iron deposits, which are mainly distributed in the North China Craton, are dominated by highly metamorphosed and deformed BIF-related iron deposits. Although these ores average only 30.35% TFe, their coarse-grained magnetite is easily recovered during processing. Sedimentary–metamorphic iron deposits are the most common of the iron deposit types in China and account for approximately 56.3% of the proven ore reserves in the country. Iron skarn deposits in China occur along or near the contact zones between Mesozoic intermediate-felsic, medium- to shallow-level intrusions and carbonate country rocks. They are one of the most important suppliers of high-grade magnetite ores in China. Magmatic Fe–Ti–(V) deposits, which formed in Proterozoic basement rocks during the late Paleozoic Hercynian orogeny, are hosted by mafic–ultramafic complexes with Ti–V-rich magnetite as the major iron ore mineral. Volcanic rock-hosted iron deposits are divided into those hosted by marine and continental volcanic rocks, with magnetite as the main ore mineral in both. Marine volcanic rock-hosted iron deposits are mainly distributed in late Paleozoic rocks of the Altaishan and Tianshan Mountains in the Xinjiang Uygur Autonomous Region. Continental volcanic rock-hosted iron deposits are mainly distributed in the Yanshanian (late Mesozoic) Na-rich intermediate-mafic rocks of the Ningwu and Luzong basins in the Middle–Lower Yangtze River Valley. Sedimentary-type iron deposits are dominantly hosted in Devonian clastic marine formations in southern China and in Mesoproterozoic marine strata in northern China, with hematite as main ore mineral. All of the weathering–leaching iron deposits in China are small in scale, and they have little economic value.

It is necessary to study the reliability of highway and transportation network. The highway and transportation network model was constructed and the degree centrality was measured, at last the reliability of Road-model was analyzed with different nodes failure strategy.

With the growth of the total mileage of highway. There is great importance in studying highway safety. At the present time, there are little research on traffic safety with the consideration of the Keep-Right-Except-To-Pass Rule, which requires drivers to drive in the right-most lane unless they are passing another vehicle. Based on Cellular Automata, this paper constructs a new model of highway safety with the consideration of the particular Rule. To evaluate the safety of the road, the model proposes a new index based on energy conservation law. After the simulation, the result shows the best traffic density to balance the safety and traffic flux is 20.1133veh/km.

Facing to the current environment, energy pressure and wind power development at home and abroad, combined with the actual situation of North China Power Grid, this paper analyzes the wind development in North China firstly, and then based on C# language and the Oracle database develops based on B/S mode of wind power monitoring informing system. This system includes monitoring module, wind data mining module, data management module, real-time alarm module, and the user management module, which realized the wind power in North China Grid remote monitoring and statistical analysis of the data, to ensure data consistency.

BIFs (banded iron formations) in China, which account for approximately 64% of the total identified resources in the country, belong to two categories: a predominant Neoarchean Algoma-type and a few Paleoproterozoic Superior-type. A minor group of BIFs developed in the Neoproterozoic is also representing, having possible correlation with the “Snowball Earth” scenario. Spatially, the BIFs in China are mainly distributed in the North China Craton. They experienced intense metamorphism and deformation, which led to the majority of iron oxides changing into coarse-grained magnetites. Though their ores generally contain only 30% TFe, the BIFs are potential targets of industrial exploitation by magnetic beneficiation. On the basis of ore-forming age, host formations, mineral assemblages, and grade of the ores, the BIF-related iron deposits in China are classified into seven types. (1) Anshan-type: Neoarchean volcanic sedimentary formations with magnetite as the main ore mineral (20% ≤ TFe

The Damiao type iron deposit is hosted in a typical Proterozoic anorthosite complex in the northern North China Craton. The types of ores in Damiao mainly comprise massive Fe ores, massive Fe–P ores, and disseminated Fe and Fe–P ores. The disseminated Fe and Fe–P ores formed by fractional crystallization are generally hosted in oxide-apatite gabbronorite and account for 70% of the proven reserve of the Damiao type iron ore. The massive Fe and Fe–P ores account for 30% of the proven reserve of the Damiao type deposit iron ore and generally occur as irregular dykes or veins filling vertical fractures of the previously consolidated anorthosite, showing typical features of hydrothermal mineralization. The contact between the massive orebodies and wall rocks is sharp and straight. The anorthosite comprises white and dark varieties, with the former resulted by the alteration of the latter that occurs as relicts. Petrographic observation and electron microprobe analyses show abundant Fe–Ti oxide inclusions in plagioclase which impart the dark color to the rock. The similar spider diagram patterns between fresh and altered plagioclase and between dark- and white-colored anorthosite imply a genetic relationship between the dark and white types. During the alteration of anorthosite, CaO and MgO were slightly decreased, the SiO2, Al2O3 and Na2O were significantly increased, and the TFe2O3 and TiO2 were significantly decreased. The TFe2O3 and TiO2 in the dark-colored anorthosite have a range of 4.86–12.18 wt.% and 0.37–1.65 wt.%, respectively. However, The TFe2O3 and TiO2 in the white-colored anorthosite have a range of 1.67–3.1 wt.% and 0.14–0.31 wt.%, respectively. These features suggest that the alteration of the anorthosite led the Fe element by leaching from the dark-colored anorthosite at highly oxidized condition, and then precipitated within the fractures of the anorthosite, thus forming the massive Fe and Fe–P orebodies. Because the estimated amount of transported Fe is much more abundant than the proven ore reserve, we infer that there should be huge potential for prospecting Damiao type iron ores.

The origin of the Zhaoanzhuang serpentine-magnetite deposit in the southern North China Craton (NCC) is highly disputed, with some investigators having proposed an ultramafic origin, whereas others favor a chemical sedimentary origin. These discrepancies are largely due to the difficulty in determining the protolithic characteristics of the highly metamorphosed rocks. Sulfur, magnesium, and boron isotope geochemistry combined with detailed petrography was carried out in this study to constrain the original composition of the Zhaoanzhuang iron orebodies. Anhydrite is present as coarse crystals intergrown with magnetite, indicating that the anhydrite formed simultaneously with the magnetite during metamorphism rather than as a product of later hydrothermal alteration. The anhydrite has a narrow range of positive &delta, 34S values from +19.8 to +22.5&permil, with a mean value of +21.1&permil, These values are significantly higher than that of typical magmatic sulfur (&delta, 34S = 0 &plusmn, 5&permil, ) and deviate away from primary igneous anhydrite towards mantle-sulfur isotopic values, but they are similar to those of marine evaporitic anhydrite and gypsum (~+21&permil, ). The sulfur isotopic compositions of several samples show obvious signs of mass-independent sulfur fractionation (&Delta, 33S = &minus, 0.47&permil, to +0.90&permil, ), suggesting that they were influenced by an external sulfur source through a photochemical reaction at low oxygen concentrations, which is consistent with the Neoarchean-Paleoproterozoic atmosphere. Coarse-grained tourmaline from the tourmaline-rich interlayers of the orebodies occurs closely with Mg-rich minerals such as phlogopite, talc, and diopside, indicating that it has a metamorphic origin. The &delta, 11B values of the tourmaline range from &minus, 0.2&permil, to +3.6&permil, with a mean value of +2.0&permil, which is much positive relative to that of magmatic tourmaline but is consistent with that of carbonate-derived tourmaline. The magnesium isotopic analyses of the serpentine&ndash, magnetite ores and the magnesium-rich wall rocks revealed a wide range of very negative &delta, 26Mg values from &minus, 1.20&permil, to &minus, 0.34&permil, with an average value of &minus, 0.80&permil, The value is higher than that of ultramafic rocks (&delta, 26Mg = &minus, 0.25&permil, ) and exhibits minor Mg isotopic fractionation. However, these values are consistent with those of marine carbonate rocks, which have lower &delta, 26Mg values and larger Mg isotopic variations (&delta, 0.45&permil, 4.5&permil, ). Collectively, the S&ndash, Mg&ndash, B isotopic characteristics of the Zhaoanzhuang iron orebodies clearly indicate a chemical sedimentary origin. The protoliths of these orebodies most likely reflect a series of Fe&ndash, Si&ndash, Mg-rich marine carbonate rocks with a considerable evaporite component, indicating a carbonate-rich superior-type banded iron formation precipitated in an evaporitic shallow marine sedimentary environment.

Organic thin film memcapacitors are designed and implemented by an organic multilayered structure, consisting of a semiconducting carrier accumulation layer and a polymer electret charge trapping layer. The capacitive states of the device can continuously and reversibly change upon programming/erasing at high biases, whereas they show nonvolatility upon reading at low biases or power off. The memcapacitive characteristics are ascribed to the modulation of the carrier accumulation threshold resulting from the cumulative and reversible charge trapping in the polymer electret layer. The organic thin film memcapacitors may provide more opportunities for developing organic-based synaptic electronic devices.

The nonlinear analytical modal of the double cranck ring-plate-type pin-cycloid planetary drive system with Multi-DOF was established. Furthermore, the influence of various parameters and clearance changing with time on dynamic response of the system was studied. The vibration mode, vibration modal and resonance frequency on various boundary conditions have been analysed, and a series of pertinent vibration and noise tests have been done. In the meantime, the machine structure and shape of main parts of the new prototype were improved to reduce vibration and noise，the dynamic characteristic optimization of the whole system was obtained. According to the results of theoretical and dynamic test analysis, the main influence factors have been found out. The theory of optimization design and method of the dynamic-response analysis of the double cranck ring-plate-type pin-cycloid planetary drive have been set up. And on the basis, the optimization design of the structure, parameters and toothpfile have been fulfilled. The theoretical basis has been provided in the design of new prototype.

Nitridated beta-Ga2O3 (100) substrate was investigated as the substrate for GaN epitaxial growth. The effects of nitridation temperature and surface roughness of beta-Ga2O3 wafers on the formation of GaN were studied. It was found that the most optimized nitridation temperature was 900 centigrade, and hexagonal GaN with preferred orientation was produced on the well-polished wafer. The nitridation mechanism was also discussed.

Housing has its distinctive life cycle from design and construction to natural utilization, to ageing and being worn and to clearance. Maintaining and renovating with scientific evaluation principles and decision making technique must be carried out to housing in order to guarantee its normal function of use during its life span and make its life span longer reasonably. The paper studies the concept of the best maintenance cycle (hereinafter designated as T m ) of housing according to its character of maintainability, and establishs the T m of housing at state of repair and renewal that by way of important direction and gist of quantitative decision-making of housing maintainability.

With the increase in the complexity of VLSI circuit design and corresponding increase in the number of logic gates on a chip, logic design errors can frequently occur. In this paper we review two representative approaches for error diagnosis and correction. They are simulation-based approach and symbolic approach. The basic ideas are presented. The two approaches are compared and the advantages and disadvantages are presented.