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  • 1  Basic Properties of Environmental Mineral Materials: Natural Self-purification of Inorganic Minerals
    LU An-huai
    2001, 20(4):371-381.
    [Abstract](7546) [HTML](0) [PDF 2.96 M](3752) [Cited by](76)
    Natural self-purification, a potential mechanism in nature whereby mankind and the Earth are interrelated with each other, has been playing an increasingly important role in the field of harnessing contamination and remedying environment. Neverthelsss, the self-purification of natural minerals widely occurring in the inorganic world has been largely ignored. This means that only half of the potential self-purification capabilities offered by nature are recognized, exploited and utilized. Utilizing most of the natural self-purification functions of both the organic and the inorganic world is a reflection of implementation of the whole self-purification function. Pollutant treatment by natural minerals is based on the law of nature and reflects natural self-purification function in the inorganic world, similar to that of the organic world. The purification function of natural minerals for reducing pollutants is reflected mainly in the basic properties of environmental mineral materials. The basic properties of this function include surface adsorption, modified porous filtration, defects of crystal structure, ionic exchange, chemical activation, physical effect and micro-effect at nanometre levels as well as mineralogical-biological interactions. A series of case studies related to the natural self-purification, which were mostly completely by our group, are discussed in this paper. Mineralogical method and biological method are well matched in pollutants disposal and jointly constitute a natural system of self-purification in terms of pollution treatment and environmental remediation in the spheres of interaction between mankind and the earth surface.
    2  40Ar/39 Ar Chronology of Intrusive Rocks from Tongling
    Wu Cailai
    1996, 15(4):299-306.
    [Abstract](7517) [HTML](0) [PDF 2.31 M](3941) [Cited by](71)
    Ar/39 Ar isotopic chronologic studies of intrusive rocks from Tongling area show that ages of these rocks are all younger than 140Ma and belong to Late Yanshanian period, with granodiorite, quartz monzodiorite, pyroxene monzodiorite and gabbro diabase being 139.8-137Ma, 137-135.8Ma, 138.2-136.6Ma and 133.7Ma respectively. On the basis of 40 Ar/39 Ar isotopic chronologic studies of these intrusive rocks, the authors have also dealt with their K Ar and Rb Sr isotopic ages, and pointed out that the age error was caused by the late hydrothermal alteration and the mixture between mantle magma and crustal magma. In addition, the mineralization ages are found to be close to the smaller ages in 40Ar/39 Ar age spectra, which is in accord with the regional metallogenic character that mineralization took place later than magmatic activity.
    3  The Origin and Geochemical Characteristics of Upper Sinain_Lower Cambrian Black Shales in Western Hunan
    Wu Chaodong Yang Chengyun
    1999, 18(1):26-39.
    [Abstract](6468) [HTML](0) [PDF 2.81 M](3688) [Cited by](59)
    This paper deals with the formation conditions of black shales based on such analytical techniques as ICP_MS, GC_MS, isotope, organic carbon, element facies and micropetrology. Studies show that the Upper Sinian_Lower Cambrian black shales were formed in an anoxic environment, and the organic sources were algae and fungi (Thallophyta). The paper points out five geochemical indicators of anoxic environment. The organic matter, especially lipids, can be well preserved in an anoxic environment. Black shale is also an indicator of the oceanic anoxic event. During the slow degradation of organism, the organic matter absorbed and combined many elements. At the early diagenetic stage, the organic matter was decomposed, and some elements were remobilized. Hence the elements exhibit multi_stage enrichment and varied forms. The key factor is the adsorption of organism and the combination with the organic matter. The strata of Ni_Mo, coal stone, barite and phosphorite deposits are controlled by the change of sea level, and the ore_bearing sets are developed in the transgressive series and condensed sections. The black shales are characterized by high content of Ni, Mo and Mn, lower total REE, comparative enrichment of HREE, and negative Ce anomaly. Geochemical and REE features indicate that black shales were deposited in an epeiric sea environment.
    4  Geochemical characteristics and tectonic setting of Qitianling A-type granitic pluton in southeast Hunan
    BAI Dao_yuan CHEN Jian_chao MA Tie_qiu WANG Xian_hui
    2005, 24(4):255-272.
    [Abstract](8083) [HTML](0) [PDF 4.98 M](3888) [Cited by](59)
    Qitianling composite granitic pluton is in the middle south of the southeastern Hunan ore concentration area. The Middle Jurassic Qitianling granite, the main intrusive body of Qitianling pluton, is studied in this paper. The Qitianling granite is composed of hornblende biotite granodiorite, hornblende biotite monzonitic granite and biotite monzonitic granite. SiO2 content increases from early to late granitic units, varying in the range of 65.92%~75.68%. The rocks are potassium-high (K2O=4.10%~5.27%, 4.86% on average) and alkali-rich (Na2O+K2O=7.12%~8.24%, 7.85% on average) ones, and have an average K2O/Na2O value of 1.63, ACNK values of 0.90~1.05 (0.96 on average) and KN/A values of 0.71~0.89 (0.78 on average), thus belonging to metaluminous to weakly peraluminous granitoids of shoshonite series and K_high calc_alkaline series. The rocks have an average ΣREE of 375.6 μg/g and show evident negative Ba,Nb, Sr, P, Ti and Eu anomalies as well as positive U, Th, Nd, Zr, Sm and Y anomalies, suggesting evident fractional crystallization. They have ISrvalues of 0.708?54~0.712?81, εNd (t) values of -5.05~-7.57 and tDM ages of 1.35~1.56 Ga, which is lower than the background age of granitoids in Hunan and Guangxi (1.8~2.4 Ga) and the region_al basement's age (1.7~2.7 Ga), implying participation of mantle materials. Various oxide and trace element diagrams for discrimination of structural environment reveal that the Qitianling granite was formed in a post_orogenic extensionalstructural environment. The authors consider that the early Yanshanian tectonicsetting in southeast Hunan and South China is a post_orogenic one instead of an intracontinental rift.
    5  A Tentative Discussion on the Ages of the Subduction-Accretionary Complex/Volcanic Arcs in the Middle Sector of North Qilian Mountain
    Zhang Jianxin Xu Zhiqin Chen Wen Xu Huifen
    1997, 16(2):112-119.
    [Abstract](3886) [HTML](0) [PDF 1.76 M](3286) [Cited by](54)
    The subduction-accretionary complex/volcanic arcs in the middle sector of North Qilian may be subdivided into subduction-accretionary complex zone and the volcanic arc zone. The former mainly comprises the Early Ordovician ophiolites, ophiolitic melanges and deep-marine flysch with features of ocean crust, within which the Middle to Late Cambrian volcanic rocks and clastic rocks characterized by continental rifting and continent-ocean transitional environment occur as lenticular blocks.Isotopic data show that the deep unit of the subduction-accretionary complex experiencedHP/LTmetamorphism during the period of 489—450Ma and the age of volcanic arcs is 495—466Ma, and that these geological bodies were formed as a result of northward subduction of Paleozoic Qilian oceanic crust beneath the Alxa blocks during the Early to Middle Ordovician.
    6  The Change from Island Arc to Rift Valley-Evidence from volcanic Rocks in Awulale Area
    Jiang Changyi Wu Wenkui Zhang Xueren Cui Shangsen
    1995, 14(4):289-300.
    [Abstract](4128) [HTML](0) [PDF 2.41 M](2747) [Cited by](52)
    The Early and Middle Carboniferous volcanic rocks in Awulale area are mainly of alkaline series, with a small part belonging to calc-alkahne series;rare earth elements show cliaracteristics of kohalaite and K-high andesite in the island arc and active epicontinental region; trace elements exhibit features of continental island arc volcanic rocks,It is thtis proved that this area was in an intra- arc environment in Early and Middle Carboniferous. Permian vol-canic rocks are of alkaline series: rare earth eiements and trace elements mani-fest features of intra-plate alkaline basalt.The rock assemblage resembles that of Kenya rift valley, being at the early stage in valley evolution. The Late Carboniferous Begeda tectonic movement led to the change of this area from island arc to rift valley and also to the tranformation of Tianshan Mountains from plate framework to intraplate framework.
    7  An Experimental Study of Adsorption Capacity of Montmorillonite, Kaolinite and Illite for Heavy Metals
    HE Hong-ping GUO Jiu-gao ZHU Jian-xi YANG Dan
    2001, 20(4):573-578.
    [Abstract](5989) [HTML](0) [PDF 1.06 M](3842) [Cited by](52)
    The experimental study on the adsorption capacity of montmorillonite, kaolinite and illite for Cu2+,Pb2+, Zn2+, Cd2+and Cr3+was conducted under the conditions of pH=4,t=23℃and very low concentrations of heavy metals. In this study, some means were used for the purpose of keeping the original concentrations of heavy metals unchanged and increasing the amount of heavy metals by adding heavy metals_bearing solution into the reaction systems. The adsorption capacities of the three clay minerals for the five heavy metals are found to be in order of montmorillonite > illite > kaolinite. Their adsorption capacities are mainly controlled by their CEC. XRD results of Cu_montmorillonite and Cr-montmorillonite show that Cu2+and Cr3+have entered the interlayer of montmorillonite by cation exchange with Ca2+. Also, adsorption capacities of each mineral are different for different heavy metals: the adsorption capacities of montmorillonite, kaolinite and illite for different heavy metals are in order of Cr3+>Cu2+>Zn2+>Cd2+>Pb2+, Cr3+>Pb2+>Zn2+>Cu2+>Cd2+and Cr3+>Zn2+>Cd2+>Cu2+>Pb2+respectively.
    8  Nd, Sr and Pb isotopic characteristics of the alkaline_rich porphyries in western Yunnan and its compression strike_slip setting
    ZENG Pu_sheng MO Xuan_xue YU Xue_hui
    2002, 21(3):231-241.
    [Abstract](3355) [HTML](0) [PDF 2.32 M](2504) [Cited by](49)
    Distributed along the Jinshajiang-Ailaoshan fault zone, the alkaline-rich porphyry zone was formed in Paleogene (from 62 Ma to 23.18 Ma). The petrochemical and isotopic geochemical characteristics of the porphyriessuggest that the tectonic setting is predominantly shear-compression and locally extension, uplifting (diapir) of the Protererzoic basement metamorphic rocks of Mt. Cangshan is also a product of the same setting. The alkaline-rich porphyry results from upward erosion of deep EMⅡfluid contaminated in different degrees by crustal components. Porphyries keep a trace of both Yangtze block and Gandwana continent, as shown by lead isotopes.
    9  Geochemical Features and Origin of Volcanic Rocks of Tiaojishan Formation inWestern Hills of Beijing
    LI Wu-ping LU Feng-xiang LI Xian-hua ZHOU Yao-qi SUN Shan-ping LI Jia-zhen ZHANG Da-gang
    2001, 20(2):123-133.
    [Abstract](3264) [HTML](0) [PDF 1.97 M](2980) [Cited by](46)
    Tiaojishan Formation in Western Hills of Beijing was dated at Late Jurassic based on the Ar-Ar ages for tachyandesites (all plateau ages and isochrone ages of plagioclase are respectively 148.91±2.98 Ma and 146.60±2.93 Ma). Geochemistry of elements and isotopes shothat volcanic rocks of Tiaojishan Formation are mainly of high-K calc-alkaline series characterized by indistinct Eu anomaly, relative enrichment of large-ion lithophile elements such as.Rb,Sr and Ba, relative depletion of high field-strength elements (e.g. Nb, Ta, Ti, Zr, Hf ), and low Nd, Sr and Pb ratios, suggesting the features of island -arc and active continental margin and enriched mantle. The authors think that volcanic rocks of Tiaojishan Formation were derived from partial melting of old-age (Archean) basaltic rocks of the lower crust and the crustmantle transitive zone by the underplating of basaltic magma during intrcontinental orogeny
    10  The discrimination between continental basalt and island arc basalt based on geochemical method
    XIA Lin-qi XIA Zu-chun XU Xue-yi LI Xiang-min MA Zhong-ping
    2007, 26(1):77-89.
    [Abstract](3296) [HTML](0) [PDF 705.61 K](3791) [Cited by](45)
    Contamination by continental crust or lithosphere can yield subduction-type signatures and lead to the misidentification of contaminated continental basalts as arc related ones. Uncontaminated asthenosphere (or plume) -generated continental basaltic rocks are normally characterized by (Th/Nb)N<1,Nb/La≥1, low87Sr/86Sr(t) ratios, high εNd(t)values, similar La/Nb and La/Ba ratios to ocean island basalts (OIB) and “hump=shaped”mantle-normalized multi-element patterns without negative Nb, Ta and Ti anomalies. As the uncontaminated asthenosphere (or plume) -generated basaltic rocks have been found in the studied volcanic successions, the possibility can be basically excluded that they belong to island-arc or active continental margin volcanic rocks. For the basic lavas with subduction-type signatures, we can judge whether they are really island-arc or active continental margin basalts by studying Zr contents and Zr/Y ratios or Zr/Y[CD*2]Zr diagram.
    11  Characters of Fe isotopes and rare earth elements of banded iron formations from Anshan-Benxi area: implications for Fe source
    李志红 朱祥坤 唐索寒
    2008, 27(4):285-290.
    [Abstract](3977) [HTML](0) [PDF 482.60 K](3929) [Cited by](45)
    Fe isotope compositions, major and rare earth elements (REE) of Archaean banded iron formations from Anshan_Benxi area, Liaoning Province have been studied. The average bulk compositions of banded iron formations (BIFs) are rich in total Fe and SiO2, but the Al2O3 and TiO2 contents are very low. These chemical features show that they are chemical sediments devoid of detrital input. REE concentrations in BIFs are very low; the shale-normalized REE+Y patterns display distinct positive anomalies of Eu, Y, and La, and depletion of light REE relative to heavy REE. This demonstrates that the BIFs are the products of chemical sedimentation from paleo_seawater with significant input of volcanic hydrothermal fluids. The Fe isotope compositions of the bulk samples are not only enriched in heavy Fe isotopes relative to IRMM-014, but also strongly correlated with Eu/Eu*, providing direct evidence for the first time that the Fe in the BIFs originate from hydrothermal fluids
    12  Kuerti Ophiolite in Altay Area of North Xinjiang:Magmatism of an Ancient Back_arc Basin
    XU Ji_feng CHEN Fan_rong YU Xue_yuan NIU He_cai ZHENG Zuo_ping
    2001, 20(3):344-352.
    [Abstract](3368) [HTML](0) [PDF 1.73 M](3048) [Cited by](43)
    The Late Paleozoic meta_basalts and gabbros exposed in Kuerti area of north Xinjiang are characterized by LREE depletion of different degrees and Nb, Ta negative anomalies, suggesting that they contain both MORB_like and arc-like components. The compositional characters of these meta_basalts and gabbros are much similar to those of the typical back-arc basin basalts (BABB) (e.g., Mariana and Okinawa BABBs). Therefore, they are presently determined to be of Kuerti BAB-ophiolite, most probably representing a crust part of the intraocean back-arc basin produced by subduction of the Paleoasia ocean. Recognition of the Kuerti BAB_ophiolite implies that the north Xinjiang area was an ancient subduction zone in early Late Paleozoic. A Paleoasia Ocean separated Siberian plate from Kazakhstan-Junggar continental plate at that time. The collision between the two continental plates and the subsequent orogeny in this area most likely took place after the disappearance of Paleoasia ocean in Carboniferous-Permian period.
    13  The Electrostatic Field Effect of Tourmaline Particles and the Prospect of Its Application to Environmental Protection Field
    WU Rui-hua TANG Yun-hui ZHANG Xiao-hui
    2001, 20(4):474-476.
    [Abstract](3209) [HTML](0) [PDF 768.00 K](3619) [Cited by](43)
    One of the most important properties of tourmaline is its electric property. Tourmalines have spontaneous and permanent poles, which form electrostatic fields around tourmaline particles with c axial planes as two poles. The effect of the electrostatic field of tourmaline can be expressed as follows: under the action of the electrostatic field, water molecules are electrolyzed and hence produce active molecules H3O and OH-, in which the former attract impurities or dirts to tourmaline surface, thus purifying the water, whereas the latter combine with water molecules to form negative ions, hence improving living conditions of the mankind; charged particles are attracted by electric fields so that charged particulates in air are attracted to tourmaline and the air is purified. Tourmaline has high mechanical and chemical stability: compared with other minerals with absorption capacities such as zeolite and montmorillonite, tourmaline shows high repeated availability without saturation limit, so its application to the environmental protection field has brilliant prospect.
    14  Geochronology, geochemistry and tectonic setting of the Late Paleozoic-Early Mesozoic magmatism in the northern margin of the North China Block: A preliminary review
    ZHANG Shuan_hong ZHAO Yue LIU Jian_min HU Jian_min SONG Biao LIU Jian WU Hai
    2010, 29(6):824-842.
    [Abstract](4014) [HTML](0) [PDF 1.02 M](5767) [Cited by](43)
    Tectonic evolution of northern North China Block (NCB) and its relation with the Central Asia Orogenic Belt (CAOB) during the Late Paleozoic to Early Mesozoic period have aroused considerable interest among earth scientists in recently years. A summary of the recently obtained zircon U-Pb or 39Ar-40Ar ages of the Late Paleozoic-Early Mesozoic magmatic rocks in the northern margin of NCB indicates that at least three stages of magmatism including Devonian (400~360 Ma), late Early Carboniferous to Middle Permian (330~265 Ma) and latest Permian to Triassic (250~200 Ma) occurred during the Late Paleozoic to Early Mesozoic period. The main components of the Devonian magmatism are syenite and monzonite, together with some other rocks such as monzodiorite, alkaline granite, rhyolite and mafic-ultramafic rocks. These rocks exhibit high alkali content (K2O+Na2O) and have alkaline to high K calc-alkaline, metaluminous or weak peraluminous geochemical features. Rocks from the late Early Carboniferous-Middle Permian intrusive suite are composed mainly of diorite, quartz diorite, granodiorite and granite, with some gabbro and tonalite. The late Early Carboniferous-Middle Permian magmatic rocks have variable SiO2 content and calc-alkaline to high K calc-alkaline, metaluminous or weak peraluminous geochemical features. Some of the late emplaced magmatic rocks (latest Early Permian-Middle Permian) display shoshonitic or alkaline geochemical compositions, indicating a trend of transition from calc-alkaline to shoshonitic or alkaline series during magmatic evolution. The latest Permian magmatic rocks consist mainly of monzogranite, K-feldspar granite, syenite, monzonite, mafic-ultramafic rocks and some intermediate-felsic volcanic rocks. They are characterized by high content of SiO2, K2O and alkali (K2O+Na2O) and display geochemical signatures ranging from highly fractionated I-type to A-type. Magmatic evolution exhibits a transition trend from high K calc-alkaline series in the early stage to the coexistence of alkaline and high K calc-alkaline series during the late stage. Compared with the Devonian and late Early Carboniferous to Middle Permian rocks, the latest Permian to Triassic magmatic rocks show much more extensive distribution. The wide distribution of the Late Paleozoic to Early Mesozoic magmatic rocks indicates a very complex tectonomagmatic history of the northern margin of the NCB during the Late Paleozoic to Early Mesozoic period. The Devonian rocks are probably related to post-collisional extension after the arc-continental collision between the Early Paleozoic Bainaimiao arc belt and the northern margin of the North China Craton during the latest Silurian to earliest Devonian period. The late Early Carboniferous to Middle Permian intrusive rocks are interpreted as subduction-related magmatic rocks emplaced in an Andean-style continental margin arc during the southward subduction of the Paleo-Asian oceanic plate beneath the NCB. The formation of large quantities of latest Permian to Triassic magmatic rocks might have resulted from post-collisional/post-orogenic lithospheric extension after final collision and suturing of the Mongolian arc terranes with the NCB.
    15  The Application of Environmental Mineral Materialsto the Treatment of Contaminated Soil, Water and Air
    Lu Anhuai
    1999, 18(4):292-300.
    [Abstract](4199) [HTML](0) [PDF 2.39 M](2436) [Cited by](42)
    Basic properties of environmental mineral materials including surface adsorption, porous filtration, ion exchange and heat effect as well as chemical solubility are put forward in this paper. They can be widely applied to such fields of tacking contamination and renovating environment as quality improvement of surface water, groundwater, rivers, lakes and ground reservoirs; improvement of soil; disposal of unclear waste; purification of domestic sewage; collection of smoke and dust and treatment of waste water. The prospective investigation and utilization of environment mineral materials are dealt with in detail with the emphasis placed on the prevention and cure of soil contaminated by heavy metals, quality improvement and treatment of surface water and groundwater and collection of smoke and dust in burning coals. The Fe,Mn and Al oxides and hydroxides together with clay minerals in soil are favorable to adsorbing 299 heavy metals in soil systems. Contaminated surface water and groundwater can be treated by natural minerals, especially those having properties of surface adsorption, ion exchange, porous filtration and chemical solubility. The metal minerals containing elements of changeable va- lences such as Fe, Mn and S can be used as good reductants or oxidants to react with pollutants in waste water. The heat effects of natural minerals and their modified products are helpful to fixing sulfur dioxide and fine grains of carbon during the burning of coals. The effective, economical and simple methods of pollutants disposal by natural minerals embody natural self_purification in inorganic world, analogous to well_known biological purification by natural plants in organic world.
    16  A Discussion on Some Problems Concerning the Study of the Emeishan Basalts
    ZHANG Zhao_chong WANG Fu_sheng FAN Wei_ming DENG Hai_lin XU Yi_gang XU Ji_feng WANG Yue_jun
    2001, 20(3):239-246.
    [Abstract](3750) [HTML](0) [PDF 1.56 M](3240) [Cited by](42)
    Emeishan basalts have become a popularly investigated field recently. This paper deals with some problems concerning the study of this topic: temporal_spatial distribution; rock associations; high_Ti and low_Ti basalts; similarity and difference between these basalts and other CFB, and their relation to mantle plume and the genesis of the plume. The new recognition and explanation of these problems are proposed, and the methods for solving them are also suggested. Answering these problems will play an important role not only in the study of the Emeishan basalts and the mantle_plume interaction, but also in the investigation of their relation to mineralization.
    17  Re-Os dating and ore-forming material tracing of the Karatungk Cu-Ni sulfide deposit in northern Xinjiang
    ZHANG Zuo_heng~ CHAI Feng_mei~ DU An_dao~ ZHANG Zhao_chong~ YAN Sheng_hao~ YANG Jian_min~ QU Wen_jun~ WANG Zhi_liang~
    2005, 24(4):285-293.
    [Abstract](3478) [HTML](0) [PDF 2.83 M](2468) [Cited by](41)
    A series of mafic-ultramafic plutons are distributed in the southern margin of Altay folded belt and many of them are associated in space and time with Cu-Ni sulfide deposits. As geologists are divided in opinion on the genesis of the mafic-altra-mafic rocks, the genesis of mineralization is still a problem of much controversy. Some chalcopyrite, pyrrhotite and pentlandite samples were collected from the No.1 and No.2 intrusions of the Cu-Ni sulfide ores inthe Karatungk deposit to carry out Re_Os dating and tracing of ore_forming materials. The two groups of measured points defined isochronal ages of 282.5±4.8 Ma and 290.2±6.9 Ma with the initial 187Os/188 Os rates being0.256 3±0.003 7 and 0.272 1±0.005 3, respectively. The data show that theore-forming age is later than that of the Early Carboniferous rocks which host the mafic-altramafic intrusions, and is corresponding to the extension stage. They share the same mineralization time with the extensively developed shear zone type gold deposits. The ages are also similar to the alkali-rich granitoids developed in the southern margin of Altay folded zone and the northern margin of the Junggar folded belt. Their initial 187Os/188 Os values and γOs values of 202.23~1 061.59 and 195.07~473.24 indicate that large quantities of crustal substances were mixed with the Cu-Ni sulfide metallogenic system in the ore-forming process. 
    18  A Discussion on the Yanshanian Magmatism in Eastern China
    ZHANG Qi ZHAO Tai_ping WANG Yan WANG Yuan_long
    2001, 20(3):273-280.
    [Abstract](3342) [HTML](0) [PDF 2.04 M](2676) [Cited by](40)
    Igneous series and distribution of the widespread Yanshanian magmatism, adakite, signification of I- and S-type granite, and the sources, tectonic settings and heat mechanism of granites are discussed in this paper. It is proposed that the tectonomagmatic discrimination diagrams, such as the diagram by Pearce et al . (1984), should be used with caution in distinguishing tectonic settings of granites. The depth of the source is considered to be the most important factor responsible for controlling the nature of granitoid rocks. Acording to the source depth, the authors have classified the granites into three types, viz., mantle-derived, lower-crust-derived, and middle-upper-crust-derived granites. The Yanshanian magmatism in eastern China resulted probably from underplated basaltic magmas generated from upwelling asthenospheric mantle in a continental crust extensional setting, and had nothing to do with the westward subduction of the Paleo-Pacific (or Izanagi) plate. Therefore, the Yanshanian magmatic rocks in eastern China do not belong to the circum-Pacific tectonic-magmatic belt. The reason, time and mechanism of delamination, however, need further detailed studies.
    19  Basin Fluids and Their Related Ore Deposits
    刘建明 刘家军 顾雪祥
    1997, 16(4):341-352.
    [Abstract](3481) [HTML](0) [PDF 2.93 M](2612) [Cited by](39)
    In the present paper basin fluids refer to extremely complex aqueous solutions which are very active in all the diagenetic-epigenetic processes of sediments during the evolution of sedimentary basins. They mainly include fluids produced by compaction and phase change of sedimenu inside the basin as well as meteoric water driven downwards into the sedimentary basin by the gravitational potential along uplifting continental marlins adjoining the basin. Pasin fluids show typical features of low-temperature hydrothermal geochemistry, with temperatures mainly ranging 80-150℃. Isotope composition and dissolved compositions of basin fluids are controlled by sediment types decided by fluid-mineral interactions) and their spatial distribulion .The contribution of organic matters plays a very impotant role in such aspects as the fluidmineral interaction the change in physical-chemical parameters of basin fluids themselves and their environments the dissolution transport deposition and ore-forming process of metals and the formation of secondary porosity of sedimentary rocks. Pasin fluids make a very important contribution to dia}enetic-epigenetic processes of sediments, oil-has production and ore-formation in sedimentary basins. Spatial distribution of sediment systems together with syndepositional faulting systems uncompacted overpressure systerns and paleotopography of sedimentary basins controlled the migration and accumulation of basin fluids and the metals carried in the fluids. Ore deposits genetically related to basin fluids can be classified into four groups, viz. sedex type deposits MVT lead-zinc deposits continental sandstone type deposits and sediment-hosted micro-disseminated fold deposits. Two examples of deposits in China formed by basin fluids one belonging to sedex the other to sediment-hosted micro-disseminated fold deposit,are beiefly discussed in this paper.
    20  A-type granite: what is the essence?
    ZHANG Qi RAN Hao LI Cheng-dong
    2012, 31(4):621-626.
    [Abstract](3404) [HTML](0) [PDF 1.21 M](5297) [Cited by](39)
    A-type granites are alkali-rich and water-poor granitoids characterized geochemically by poor Al, Sr, Eu, Ba, Ti and P. A-type granite was formed under the low pressure and high temperature conditions, and their source rocks had no choice. The essence of the A-type granites is that granitic magma melted under low pressure, and they were mostly produced in the tectonic setting of crustal extension and thinning.

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