Geological Journal of China Universities

A Review on Precambrian Tectonic Evolution of Continental Crust

QIAN Xiang-lin, LI Jiang-hai, CHENG Su-hua

2005, 11(2): 145-153.

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Precambrian tectonics represents one of the key research topics in the science of earth system．The preserved oldest continental crust is composed of felsic rocks with ages older than 3.8 Ga．As indicated by analysis of tectonothermal events，the continental blocks 3.0 Ga have been recognized，and Neoarchean cratonization is very common all over the world．It is suggested that the early geothermal gradient is comparable to that of present day by PT calculation on the basis of high-grade metamorphic rocks．Thus，the Archean continent crustal blocks were rigid enough to show kinematics，as described by present plate tectonics．Since the Mesoproterozoic(1.80 Ga)，many cratons began to develop sedimentary covers synchronously，which are almost unmetamorphosed．So，it is suggested here that Precambrian geological evolution can be divided into two stages，the early stage and the late stage． The early crustal evolution of North China craton can be well correlated with other continents，and its tectonic position within the Precambrian Supercontinet should be reconstructed．Based on the curent accumulation of research, several basic projects are proposed to focus on the frontier areas of Precambrian geology．

Geomicrobiology and Its Progress

CHEN Jun, YAO Su-ping

2005, 11(2): 154-166.

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Geomicrobiology is a new branch of earth sciences developed since the end of the twentieth century. It studies mainly the microbial processes in geologic environment and all kinds of geochemical records generated in these processes．Through microbial existence and evolution in the earth history at the various extreme environments such as high temperature，high pressure, extreme acidity and alkalinity，high salinity, very high radioactivity，large earth depth，etc．and different kinds of geochemical records in the interactions between microorganisms and their geologic environments，this discipline studies the cycling of life-essential elements(C，H，O，N，S， Fe, etc．)in the global and local scales in relation to microorganisms in the Earth’s history to set a context for further research for the microbic weathering， biomineralization，microbic ecocycling in the geologic environment and the eco1ogical environment．The present paper also concerns the interaction of microorganisms with minera1s, microbic ecology at the extreme environments，and molecular geomicrobiology．

Microbial Biomineralization

Li Yi-liang1, Wang Ru-cheng2, Zhou Gen-tao3, Zhang Chuan-lun1

2005, 11(2): 167-180.

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Microbial metabolism of life—essential elements such as carbon, nitrogen, sulfur, oxygen and metals can significantly change the physicochemical conditions of their external or internal environments．Through a variety of biogeochemical processes．microorganisms mediate the precipitation of minerals(biomineralization)or dissolution of minerals or rocks(microbial weathering)．Biomineralization can have two pathways．One is called biological induced mineralization by which organisms secrete metabolic products that result in subsequent deposition of mineral particles；another pathway is called biologically controlled mineralization by which the microbes exert a significant degree of control over the nucleation and growth of the minerals．The minerals of microbial genesis are generally characterized by small grain size and／or unique isotopic features．The most common biogenetic minerals are carbonates．sulfides and iron oxides．The structure of cell surface and the exopolymers excreted plays an essential role in forming templates for ions to condense, assemble and mineralize．Biomimetic synthesis of Earth materials helps us to understand the mechanism of biomineralization under artificial conditions．Furthermore，biogenic minerals in geological environments can be used as biosignatures，which help to retrieve the origin and evolution of life on Earth and other planets．

Weathering of Silicate Minerals by Microorganisms in Culture Experiments

LIAN Bin1 3, CHEN Jun1, FU Ping-qiu2, LIU Gong-qiang2, CHEN Ye3

2005, 11(2): 181-186.

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Interactions between microorganisms and minerals take place widely on the Earth，which lead to dissolution or precipitation of minerals and thus play an important role in the natural environment and economic development．The study of mineral weathering by microorganisms involves many fields and disciplines． Furthermore，weathering of minerals is related to the formation and evolution of soil，development of vegetation and formation of mineral deposits．This paper focuses on mineral weathering by silicate bacteria．Potassium feldspar，illite and other common minerals were selected for this study．These minerals were incubated in nitrogen—free medium containing bacteria．During incubation samples were collected from the culture and analyzed using X—ray diffraction and electron microscope．The results showed that the bacteria indeed eroded the surface of the testing minerals，which were characteristic of round shapes and uneven surface．The mineral particles were covered with numerous bacteria．Furthermore．bacteria selectively degraded different minerals due to difference in mineral crystal structure．In the absence of bacteria，minerals remained intact，which were characterized by sharp edges and corners．The mechanisms of mineral weathering by silicate bacteria were also discussed．

Qinghai Lake：A Natural Laboratory for Geomicrobiological Research

TUO Jin-cai1, CHEN Jun2, YAO Su-ping2, JI Jun-feng2, LI Yi-liang3, ZHANG Chuan-1un3

2005, 11(2): 187-193.

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Qinghai Lake is located in the northeastern edge of the Tibetan—Qinghai Plateau．It is the largest saline lake in China．Due to uneven uplift of the plateau, some of the basins formed lakes in an isolated drainage system．The geochemistry of bedrocks affects the hydrological chemistry of drainage area and the physicochemical features of the Qinghai Lake．The main source of organic carbon is the ecological system surrounding the lake；Weathering of rocks also contributes to the carbon source in the lake．The chemistry of the Lake is heterogeneous in both vertical and horizontal dimensions；Changing of seasons also influences the hydrochemistry． These characteristics bring forth a unique microbiological ecology as well as a coupled carbon and metal cycling system． Enhanced concentrati0ns of Fe，SO42-, CO32-, Ca，Mg ions provide sufficient nutrients for the prosperity of a complex ecological system． Thisbiological cycling consequently provides sufficient chemicals for biomineralization． As has been surveyed, the lakeis of high diversity of algae，whose populations and community structures change seasonally． As a Dart 0f the evolution of the lake，the biological relics have been recorded as organic or inorganic biosignatures in the bottom sediments．Further study of the biological records and their relationship to the evolution of the local microbial ecology and cycling of carbon and other elements is expected to have important implications for climatic and environmental changes in the Tibetan—Qinghai P1ateau．Qinghai Lake

Preliminary Study on Surface Properties of Iron Sulfate Formed by Microbially Induced Mineralization

LU Xian-cai, LU Jian-jun, ZHU Chang-jian, LIU Xian-dong, WANG Ru-cheng, Ll Qi, XU Zhao-wen

2005, 11(2): 194-198.

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It is well demonstrated that microbe—mineral interaction plays an important role as a geologic agent in the evolution of epigenetic system．There is a dynamic exchange of elements between microorganisms and minerals，which affects the surface structures of the minerals．The dissolution and crystallization of minerals are remarkably affected by metabolic activities of microorganisms through creating microenvironment at the interface or interaction with metabolic byproducts．As the biomineralization products，the newly formed minerals generally record much information about the influence of microorganisms，which can be evaluated by surface characterization．This paper analyzes the specific area，pore structure，fractal dimension and surface energy of three types of iron sulfates formed by microbiological and abiotic chemical processes，respectively．The results show that schwertmanite and jarosite are formed in the 9 K culture medium due to inoculation of Thiobacillus ferrooxidans；whereas，only jarosite was formed under the abiotic contro1．The particle structure，grain-size distribution and surface energy are quite different between the microbially and abitoically formed minerals．

Microbial Bioremediation of Metal-and Radionuclide-Contaminated Soils and Groundwater

Ye Qi 1 2, Zhan Chuan-lun1 2

2005, 11(2): 199-206.

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Contamination of environments by heavy metals and radionuclides has become a serious problem worldwide．The treatment of heavy metals and radionuclides in environments by specific microorganisms such as meta1-reducing and metal-resistant bacteria has become promising technology．The successful application of in-situ bioremediation will provide potential ways to clean up heavy metals and radionuclides in contaminated environments．Recent studies also focus on understanding the effect of heavy metals and radionuclides on the microorganisms in the microbial community．Microbial mats and biofilms are two representative microbial communities functioning in bioremediation．Metal speciation and valence variation, transport processes，and microbial metabolism are three important ingredients for metal and radionuclide remediation．Combining these ingredients enables us to better understand the relationships between the naturally occurring microorganisms and bioremediation processes．

Diversity and Evolutionary Implications of Thermophilic and Non-thermophilic Crenarchaeota

Huang Zhi-yong, Wang Yi-min, Zhang Chuan-lun

2005, 11(2): 207-216.

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Crenarchaeota are of the three Kingdoms in Archaea with the other two Kingdoms being Euryarchaeota and Korarchaeota．While Euryarchaeota have long been recognized as an important group of the prokaryotes and have been well studied，Crenarchaeota and Korarchaeota have received increasing attention only recently．This review focuses on Crenarchaeota because recent advances in ecological and evolutionary studies of Archaea have mostly occurred in this kingdom．One important observation is that all isolated species of Crenarcheota are extremely thermophilic．whereas non-thermophilic Crenarchaeota have so far resisted attempts of isolation．Thermophilic Crenarchaeota are mostly found in deep sea hydrothermal vents and terrestrial hot springs，which are characterized by growth at high temperature(>80℃)and low pH(<6)．A variety of thermophilic Crenarchaeota can use reduced inorganic chemicals such as H2，and reduced sulfur for chemoautotrophic growth．This trait，along with the group’s deep branching in the tree of life，has lead to the belief that the last common ancestor of life may be a thermophilic autotroph growing in a hydrothermal system．Non-thermophilic Crenarchaeota have a very close phylogenetic relationship to the thermophilic Crenarchaeota． Although currently unculturable， non-thermophilic Crenarchaeota have been increasingly recovered from low-to moderate-temperature environments, which range from open marine to terrestrial soils．1akes．and subsurface．This is largely due to the development of the culture．independent molecular techniques，such as sequencing of the 16S rRNA genes．Furthermore，studies of non-thermophilic Crenarchaeota in oceans and soil suggest that certain members of the non-thermophilic Crenarchaeota may have very important roles in the biogeochemical cycling of carbon．

Geochemistry and Microbiology of Hot Springs in Kamchatka, Russia

Zhao Wei-dong1 2, Christopher S．Romanek2 4, Gary Mills2 4, Juergen Wiegel3, Zhang Chuan-lun1 2

2005, 11(2): 217-223.

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Kamchatka is one of the most active regions of volcanism in the world because it is located in the transitional zone where the Eurasian plate，North American plate and Pacific plates meet．As a result，Kamchatka has numerous hydrothermal systems，which constantly release geothermal gases anti fluids out 10 the earth surface．Geothermal gases such as N2 and CO2 may prevail in the outflows but H2，CH4 and H2S occur frequently． Hot spring waters in Kamchatka may have multiple origins including meteoric and magmatic water．The temperature of these hot springs ranges from ～20 ℃ to greater than 90℃．Water chemisitry also varies dramatically with pH ranging from 3.1 to 9.8．Hydrothermal fluids are sodium chloride water dominant and may contain various dissolved constituents including K+ ，H3BO3，H4SiO4， Ca2+，and S042- ．Volcanic ore—formation prevails in the high thermal activity regions in Kamchatka and precipitates may be dominated by silica crusts，sulfur anti Hg—Sb—As—FeS deposits．Oils are also generated in the region and dominated by n-alkanes．More than 24 novel thermophilic microorganisms have been isolated from hot springs in Kamchatka．Most of these isolates are heterotrophs；however，autotrophs may be equally abundant depending on the spring conditions．Collectively，these organisms may play important roles in biogeochemical cycling of carbon，sulfur and iron in the hydrotherm al system．Culture-independent approaches and quantitative methods are now employed to enhance our understanding of the ecology and biogeochemical functions of microorganisms in Kamchatka hot springs．

Knowing the Unknown：Statistical Approaches towards Understanding Microbial Diversity

Wang Yi-min, Huang Zhi-yong, Zhang Chuan-lun

2005, 11(2): 224-233.

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Molecular techniques，such as denaturing gradient gel electrophoresis(DGGE)，16S rDNA clone library，and DNA microarray, reveal extraordinarily divers species in the natural environment．Most of these species are unculturable and cannot be characterized precisely．Empirical indices like Shanon and Simpson have been traditionally used to evaluate the diversity． These indices，however, have certain disadvantages because of their dependence on sample sizes. To overcome such disadvantages，three approaches have been developed，which include parametric estimation, nonparametric estimation，and phylogenetie diversity estimation． These methods when integrated with molecular techniques． can enhance accurate estimation of species richness and diversity，and allow rigorous comparisons of different communities

SEM Study on Jarosite Mediated by Thiobacillus ferrooxidans

ZHU Chang-jian, LU Jian-jun, LU Xian-cai, WANG Ru-cheng, LI Qi

2005, 11(2): 234-238.

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Jarosite is a major secondary mineral formed in acid supergene environment by oxidation of metal sulphide．Thiobacillus ferrooxidans occurring extensively in metal sulphide ore district has an important effect on oxidation of metal sulphide and formation of secondary minerals．In order to discuss the effect of Thiobacillus ferrooxidans on the formation of jarosite，two parallel experiments were conducted for preparation of jarosite：chemical experiment and biologically mediated experiment．The compositions and morphological features of these two groups of jarosites have been investigated by means of XRD，SEM and EDS．The study indicates that full propagation of Thiobacillus ferrooxidans in the solution is beneficial to the formation of jarosite．The oxidation rate of Fe2+in the solution is probably the main factor that affects crystallization of jarosite．Thiobacillus ferrooxidarts induces a rapid crystallization of jarosite by increasing the supply rate of Fe2+ on the mineral surface．Jarosite mediated by Thiobacillus ferrooxidans has a better crystalline form than that synthesized by chemical method．

Ion Microprobe：Techniques and Applications in Cosmochemistry and Geochemistry

HSU Wei-biao

2005, 11(2): 239-252.

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Ion microprobe offers in situ analyses of trace element abundances and isotopic compositions with a micrometer spatial resolution．It has a wide range of cosmochemical and geochemical applications． The technique has been particularly important in meteorite research where isotopic and chemical abundance anomalies are at their largest．This paper highlights the successful application of ion microprobe to a variety of research areas in cosmochemistry and geochemistry，and reports 26 major and trace element sensitivity factors determined in 11 silicate standards.

Comparision between Bloodstone Deposits in China and Mercury Deposits in Okhotsk—Chukchi Volcanic Rock Belt,Northeastern Russia

Guo Ji-hun, Zhang Xue-yun, Li Jia-gui, Zhu Wen-bin, Zhang Ni

2005, 11(2): 253-259.

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Bloodstone is an unique Chinese precious stamp stone，consisting of “blood” (fine-grained cinnabar aggregate) and “ground” (fine-grained dickite aggregate)．Up to now，the bloodstone deposits were discovered only in Changhua of Zhejiang Province and Balin of Inner Mongolia，which are situated in Mesozoic－Cenozoic circum－Pacific active continental margin of China．Comparative studies show that some mercury deposits in Okhotsk－Chukchi volcanic rock belt of northeastern Russia possess many similarities with Chinese bloodstone deposits in many aspects，including regional tectonic setting，volcanic host rocks，ore-controlling structure and ore—body morphological feature，alteration of host rocks，sub-volcanic rocks and genesis of the deposits．Some mercury ores from the mercury deposits may be used as bloodstone gems in the near future．

Study on the Raman Spectra and XRD for Thermotransformation of Serpentine Cat’s Eye from Shimian,Sichuan Province,Southwest China

LU Bao-qi1, QI Li-jian2, XIA Yi-ben1, WANG Ci-yin3

2005, 11(2): 260-263.

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Abstract：Raman spectra and X-ray power diffraction(XRD)were used to study the process and products of thermotransformation of serpentine cat’s eye，which was firstly discovered at the asbestos deposit of Shimian town，Sichuan Province，Southwest China and could display excellent cat’s eye effect if polished properly．The results show that the final products of thermotransformation of the Sichuan serpentine cat’s eye are crystalline forsterite and crystalline enstatite．Heated up to 500℃ for two hours, the Raman spectrum pattern of Sichuan serpentine cat’s eye remains intact，indicating its stable internal structure and good resistance to relatively high heat；Up to 700℃ ，the characteristic Raman bands 824 and 854 cm-1 are clearly observed，indicating the appearance of forsterite，along with the appearance of the overlapped bands 686 and 340 cm-1of noncrystalline enstatite; At 800～900℃, the crystallization of forsterite increases，meanwhile，crystalline enstatite begins to appear．When heated to 1000℃ ，the amount of forsterite decreases apparently．Up to 1000℃, the amount of enstatite increases rapidly．

Study on Beizhang and Lianglong Granites and Their Dark Enclaves

CHEN Rong, XING Guang-fu, YANG Zhu-liang, SHEN Jia-lin, ZHOU Yu-zhang

2005, 11(2): 264-275.

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Late Mesozoic granites in eastern Zhejiang province can be subdivided into three types according to their lithology：monzonitic granites (with an isotopic age range of 85～101 Ma)，K-feldspar granites(100～110 Ma)，and A-type granites(90～109 Ma)．The last two types are well studied, but no enough attention was paid to the first one．In this contribution，Beizhang and Lianglong plutons，as representatives of monzonitic granites in eastern Zhejiang，dark enclaves hosted in monzolitic granites，and associated quartz diorites are selected to discuss their characteristics and genetic relations．We have systematically studied their petrological and geochemical characteristics，and have concluded that monzonitic granites in eastern Zhejiang belong to meta—aluminous，calc-alkaline series，I-type granites with a relatively higher Mg#. Both the monzonitic granites and the associated dioritic rocks show geochemical feature of volcanic arc magmas，characterized by enriched large ion lithophile elements (LILE) and light rare earth elements (LREE) relative to the high field strength elements (HFSE)．This is consistent with early Cretaceous basalts from eastern Zhejiang．Major and trace elements (or ratios) covariations suggest that the monzonitic granite and dioritic rocks were resulted from mixing of mantle-derived basic magma and crust-derived acid magma in different proprotions．With a range of isotopic ages from 85 to 101 Ma，the formation age of monzonitic granite and quartz diorites is contemporary with the late Mesozoic A-type granites in coastal area of Zhejiang and Fujian Province．This may be a hysteresis effect of volcanic arc magma． The dark enclaves in Beizhang monzonitic granite are mafic microgranular enclaves (MME)．The MME and the host rocks are similar in REE patterns，but the MME have higher total REE contents and the element ratios between the MME and host rock are nearly constant．The MME，which are relatively more mafic，contrarily have higher Rb，Zr，La，Nb，Cs，Ti，Ga contents，and lower Sr，Ba，Cr contents than the host rocks．This is quite different from the element distribution produced by crystallization—differentiation of magma，and indicates that some elements were enriched during formation of the MME．The ratios of Mg/(Mg+Fe)and Na/(Na+Ca)in the MME and their host rocks are very close(0.39～0.43 and 0.66～0.77 respectively)，indicating that the formation of the MME is related to the immiscible fractionation of the magma．

Lead,Carbon and Sulfur Isotopic Compositions of the Xianshi Uranium Deposit,Northern Guangdong Province

YE Hai-min1 2, SHEN Wei-zhou1, LING Hong-fei1, DENG Ping3, PU Wei1, TAN Zheng-zhong3

2005, 11(2): 276-280.

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The Xianshi uranium deposit is located in the eastern part of the Guidong composite granite body．The uranium ore bodies occur in the intersection parts of the NWW-trending diabase dikes and the NEE-trending sillicification zones．The pyrite in the deposit is characterized by enrichment of radiogenetic uranium lead，(206Pb/204Pb)i= 18.756～23.883，(207Pb/204Pb)i= 15.676～15.932 and (208Pb/204Pb)i=38.530～38.938，main1y plotted in the range of the basement metamorphite lead．The calcite of uranium deposit hasδ13C values of –8.5～-3.1‰, which coincides with the mantle δ13C values(-5±2‰)．Theδ34S values of pyrite (-10.1～-8.3‰) is close to the δ34S values of pyrite in the granite (-10.9～-8.1‰) and markedly different from the δ34S values of pyrite in the diabase dike (-0.03～2.1‰)．Based on the lead，carbon and sulfur isotopic signatures．it is proposed that the ore-forming materials of the Xianshi uranium deposit display multiple．resourced characteristics．

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