Table of Content

20 March 1997, Volume 3 Issue 1

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Article

THE GEOCHEMISTRY AND GENESIS OF THE LAOSHAN GRANITOIDS, SHANDONG PROVINCE

Zhao Guang-tao1, Wang De-zi2, Cao Qin-chen1

1997, 3(1):  1-15. 

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The Laoshan granitoids, distributed in the middle part of the Northern Jiangsu-Southeastern Shandong tectonic zone, is a typical Mesozoic granitic complex composed of calc-alkaline and peralkaline groups. The calc-alkaline group includes three units of ganitic rocks: quartz monzonitic granite, biotite monzonitic granite and syenogranite unit, while the peralkaline group comprises a series of alkaline or peralkaline granites characterized by occurrence of alkaline melanic minerals such as arfvedsonite and aegirine. The emplacement ages determinated by zircon U-Ph method of the four above units are 146.8, 126.2. 113.0 and 110.8Ma respectively. There exists evident evolutionary trend indicated by increasing Si, alkaline and decreasing Al, Ca, Mg from quartz monzonitic granite, biotite monzonitic granite to syenogranite unit in the calc-alkaline group, while the alkaline granite is generally of higher Si, alkaline and lower Al, Ca, Mg and especially rich in Ga, Nb, Hf, Zr, Y and of high F/Cl, Ga/Al ratio, similar to typical A-type granite in the world. Based on the data of Sr, Nd, Ph, O isotope and the study of rock-forming mechanism, the authors presented that both groups of the Laoshan granitoids were derived from the similar source of metamorphic rocks of the lower crust basement, the Jiaonan Group, but related to two different partial melting events. In the first event, the calc-alkaline magma was generated to form three units by different degrees of fractional crystallization, while the alkailine granite was possibly generated from the remelting of the “restite” in the second event and through AFC process. Based on the results from a series of geochemical diagram and the regional tectonic development, it is suggested that the Laoshan granitoids are the products of a special period of tectonic evolution in the continent-continent collision transpression orogenic zone between Jiaobei terrane and Jiaonan terrane, of which the talc-alkaline group was formed at the compressive environment transpreesion or the transitiona1 environment from transpression to transtension, while the alkaline granite was definitely formed at the tensional environment. The latter can be considered as a mark of the ending of Mesozoic orogenic movement in the eastern Shandong area.

A STUDY ON THE TEXTURE 0F BIOTITE IN GUERET GRANITE，FRANCE

Wu Ji-min

1997, 3(1):  16-22. 

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The aim of this paper is to propose a quantitative analysis of the texture, including density, size, shape and spatial distribution, of the biotite in Gucret granite by thin section study Results are inferred by means of basic principles of morphological mathematics, image analysis, and stereological methods. According to the gray scale characteristics of the biotite in thin sections, their gray images can be obtained by using a direct micro photo-charting. Then, the method of an automatic thresbolding used to extract the particles of the biotite in order to form binary images. The parameters, e.g. the area and perimeter for the biotite particles, can be estimated in the binary image with the help of MIPS system. The analyses of the denity, size, shape and spatial distribution for biotite particle show an anisotropic characteristics in the granite Meanwhile, Weibul, Normal and Poisson models can describe the distributions of size, shape and the spatial distribution respectively.

A COMPARISON BETWEEN C0SMIC SPINEL AND TERRESTRIAL SPINEL

Wan Yu-qiu1, Wang Erkang1, Zhang Wen-lan2

1997, 3(1):  23-30. 

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Magnetic spinels are reported in all extraterrestrial objects which have experienced melting in the earth atmosphere, such as in the fusion crusts of meteorites and micrometeorites, in the chondritic extraterrestrial particles extracted from deep-sea sediments, and in polar ice, and in glassy microspherules from a late Pliocene impact. Based on above-mentioned reports as well as our studies of cosmic dusts from Suzhou granite, an introduction to the physical and chemical characteristics of “cosmic” spinels, such as the section appearances, chemical compositions, occurrence features and their origins, as well as a comparison with terrestrial spinels, is given in this review. Cosmic spinels usually display dendritic, skeleton, cruciform and octahedral morphologies, which are characteristic of rapid crystallization from a high-temperature melt. They contain variable amounts of MgO, Al2O3, and Cr2O3, with high NiO and relatively low TiO2. The average bulk composition of cosmic spinels is expressed as a solid solution of spinel end members, showing that the two dominant components are magnetite and magnesioferrite. All cosmic spinels have a trevorite content. Cosmic spinels always display a relatively high iron oxidation state, usually being characterized by a Fe3+/Fetotal ratio greater than 70%, and even higher, nearly reaching 100 atom% in late Pliocene microspherules and Suzhou granite cosmic dusts. But for the terrestrial spinels, they contain no more than 1 mol% trevorite. Magnesioferrite is also rarely present. All terrestrial spinels generally have a Fe2+/Fetotal ratio less than 70%, and have not been reported to be with a dendritic, skeleton or octrahedral morphologies in their sections. Cosmic spinels are characterized by a high nickel concentration due to the relatively high abundance of this element in extraterrestrial and a high iron oxidation state resulting in crystallization under a high oxygen fugacities. So it is suggested that the cosmic spinels in the geologica1 record are of two implications: they are a marker of cosmic material and they contain informat[on about the mode of accretion of this materia1.

THE FEATURES OF LATE PALEOZOIC TECTONO-MAGMATIC ACTIVITY AND CRUSTAL REVOLUTION IN THE S0UTHERN SUZUOQI AREA

Zhang Chen, Li Mao-song

1997, 3(1):  31-39. 

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Post-orogenic extension had occurred in I ate Paleozoic at northern margin of the North China Platform. The orogeny occurred in late Devonian-Early Carboniferous and foreland basin is formed and accumulated littora1-epicontinental sea facies molasse deposition and formed a lot of synorogenic granites. Intracontinental extension tectonics process occurred in Middle Carboniferous-Early Permian which formed a lot of volcanic rocks. The alkalian content of volconic rocks is high (Na2O> K2O) and the differentiation index of volcanic rocks is characterized by bimodality. Composition and texture maturity of clastic rocks indicates that extensional process occurred from Middle Carboniferous to Early Permian.

CHARACTERISTICS 0F METAM0RPHISM IN THE HARLIK METAM0RPHIC BELT，EAST XINJIANG, AND ITS TECTONIC ENVIRONMENT

Zhao Ming, Shu Liang-shu, Wang Chi-ying

1997, 3(1):  40-50. 

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Based on researches of metamorphic rocks and minerals in the metamorphic belt in Harlik, the authors suggest that the metamorphic belt underwent two metamorphic stages. The first stage was the regional thermal metamorphism of high-temperature (T= 922～780℃)and low-pressure during the early-middle Carboniferous of late Paleozoic. The second stage was the regional faulting metamorphism of medium-temperature and medium-pressure (T= 450～670℃, p= 2.3～ 4.1Kb)during the end of Carboniferous. The second stage can be divided into four metamorphic zones, retailed research suggests the following tectonic evolution mode1: Therma1 metamorphism was related to intra-island-arc tension, while regiona1 faulting metamorphism was caused by A-type subduction in the process of collisional orogeny.

A STUDY ON EVOLUTION FEATURES OF CANG-DONG FAULT Z0NE BY USING GEOPHYSICAL DATA

XU Ming-jie, Zhu Wen-bin, Hu De-zhao, Wang Qin, Ma Rui-shi

1997, 3(1):  51-61. 

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Cangdong fault zone is the west boundary fault of Huanghua depression. It was a reverse fault in Mesozoic era and became a normal one in Cenozoic ear. It controls the structural evolution of the depression，and hence plays an important role in the transportation and enrichment of oil and gas. We analyze 23 seismic cross-sections in southern and center parts of Cangdong fault zone, obtain fault throw and strata thicknesses, by using synthesized gravity and magnetic data, quantitative researches on the structural evolution of Cangdong fault zone and the western Huanghua depression show that; Cangdong fault zone can be divided into four temporal stages and six spatial sectors. It strongly affected the conversion of western Huanghua depression. The NWW faults in the depression adjusted the conversion of structure patterns.

A FOUNDATION SUITABILITY MAP OF NANJING CITY, JIANGSU PROVINCE, P.R. OF CHINA

Salah Bishir, Luo Guo-yu, Yan Chang-hong, Chen Zheng-zhou

1997, 3(1):  62-77. 

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To meet the growing requirements for suitable and safe constructional lands, methods of land-use evaluation are being rapidly developed in engineering geology. The paper deals with setting up a foundation suitability map for Nanjing city. The bedrock geology, topography, the depth to the bedrock and the Quaternary geotechnical soil maps are utilized to achieve this goa1. For simplicity and from practical point of view, the pre-existing maps are modified in simple versions. Each map is separated into areas of different ranges. The zoning map of the engineering geological conditions is prepared by simple superimposing transparent overlays of the four basic data maps. Each zone is rated and five classes of ground conditions fire fabricated.

MECHANISM OF DEFORM ATION AND DESTROY OF ROCK-SOIL MASS AND MODELS OF SHAFT RUPTURE

Li Ding-long，Zhou Zhi-an

1997, 3(1):  78-86. 

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Based on the hydrogeological and engineering condition of rupture shaft and other background information of Linhuan mine area, hydrogeological model of this mine is estab1ished, the influence factors and forming process of deformation and destroy of the bottom aquifer soil and the weathered basement are analyzed. The four development stages of deformation and destroy of rock-soil mass and four models of shaft rupture are first put foreword. Some regularites of shaft rupture are obtained. Mechanism of shaft rupture s exposed. This study provides scientific data for controlling the shaft rupture and evaluating the stability of shaft.

STRATIGRAPHIC DIVISION AND CORRELATION OF THE MESOZOIC STRATA IN SHANDONG

Li Shou-jun1, He Wen-yuan2

1997, 3(1):  87-93. 

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The study of Mesozoic fossils and volcanic rocks in Shandong shows that there are both Jurassic and Cretaceous strata n the west of Yishu fracture zone (including areas of southwest, central and north Shandong), while only Cretaceous strata in the east of this zone (namely, east Shandong). The authors consider that the Fangzi Formation belongs to the Lower to Middle Jurassic, the Santai Formation to Middle Jurassic, the Fenshuiling Formation to Upper Jurassic, the Laiyang, Qingshan and Xiwa Formations to Lower Cretaceous, and the Wangshi Formation to Upper Cretaceous. The authors abolish the Mengyin Group (Formation) and the Wennan Sub-formation, and suggest that the “Wangshi Formation” used in north Shandong should be abolished and a new name should be established.

SPORO-POLLEN ASSEMBLAGE FROM THE MIDDLE JURASSIC XISHANYAO FORM ATION OF THE TAIBEI DEPRESSION IN TUHA BASIN

Ji Liming

1997, 3(1):  94-105. 

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The Taibei Depression is the main oil and gas bearing area of Tuha Basin, and the coal bearing stratum of the Xishanyao Formation is the most important source rock in the area. The sporo-pollen fossils from the well pu-1 and wel1 Caonan-l have been analyzed, identified and counted. The sporo-pollen fossils discovered from the Xishanyao Formation consist of 31 genera and 57 species. The assemblage is named as Cyathidites-Cycadopites-Quadraec-ulina based on their high percentages and stratigraphic significance. It is characterized by the slight dominance of gymnospermous pollen(51％). The pteridophyta spore amounts to 49％. The genera Cyathidites and Osmundacidites of the pteridophyta spores are predominant, their percentages amounting to 20％ and 13％ respectively. Gleicheniidites, Asseretospora and Deltoidospora are common, their percentages being 2-4％. Among gymnospermae pollen, the most abundant genera are Quadraeculina (17.5％ )and Cycadopites(13.3％). Moreover, Podocarpidites, Piceites and Classopollis are of higher percentage (3.5％, 5.5％ and 4.9％ in order). By analysing the geological distribution of main classes and important species and genera, comparing with the known assemblages which are of the same geologic age from the various districts in the world, and considering the conformable relationship of the Xishanyao Formation with the underlying late Early Jurassic Sangonghe Formation, the author thought that the assemblage of the Xishanyap Formation is similar to the ones from the Yanan Formation of Central Shanganning Basin, the Haifanggou Formation of Western Liaoning Province etc. The geologic age might be referred to early Middle Jurassic(Aalenian-Bajocian).

THE STUDY ON SIMULTANEOUS DETERMINATION OF IMPURE RARE EARTH ＆ NON-RARE EARTH ELEMENTS IN HIGH PURITY YTTRIUM OXIDE BY ICP-AES

LU Bao-yuan1, QIU Li-wen2

1997, 3(1):  106-110. 

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High purity yttrium oxide is widely used in various fields. The purity of products affects their quality directly. It is necessary to develop a sensitive method for the accurate determination of trace impurities in high purity yttrium oxide. In this paper, the authors put forward an analytical method that 30 elements, i.e. La, Ce, Pr, Nd, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yh, Lu, Al, Ba, Ca, Cu, Cr, Cu, Fe, Mg, Mn, Ni, Pb, Si, Sr, Ti, V, Zn in high purity Y2O3 are determined directly by ICP-AES. The writers studied the spectral interference of yttrium and the effect of Y203 matrix and background, and selected the spectral lines of determined elements. The trace impure elements in Y2O3 standard are determined with standard addition method, and the determined results are used as 1ow standard values, so that the determining errors can be cleared up because of neglecting trace impurity elements in Y2O3 standard, and the optimum operating condition is chosen. The detection limits of 30 elements are from 0.003 to 1.3μg/g. This method can satisfy the needs of quality control of high purity Y 203 products and commodity inspection.

DETERMINATION OF CHLORINE IN ROCK SAMPLES BY GASIFICATION-ION CHROMATOGRAPHY

Lin Yu-ping

1997, 3(1):  111-114. 

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Chlorine is a volatile element in the acidic media for its activity in chemistry, and can be absorbed by alkali substance. The present paper introduces a method of chlorine determination in rock samples by ion chromatography after treated in a sealed gasification absorber. Good results in both accuracy and precision have been obtained for various sample analyses with this method which has no pollution and is convenient in manipulation.

COMMENTS ON Spirisosphaerospora pacifica AND Miniactinomyces chinensis IN PELAGIC MANGANESE NODULES

Zhang Zhong-ying

1997, 3(1):  115-117. 

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In this paper, some comments on the newly-discovered “nanometer-scale ultramicrofossils” (Spirisosphaerospora pacifica and Miniactinomyces chinensis) in pelagic manganese nodules from the East Pacific Ocean are made. Because the morphology of these “fossils” is uncertain, at present the evidence for a microbial origin and their biological affinites can not be regarded as conclusive. Much further work, therefore, is needed to clarify the true nature of these problematic microorganisms.

A PRELIMINARY DISCUSSION ON THE RESEARCH OF LITH0SPHERE TECTONIC EVOLUTION 0F SOUTHEAST CHINA

Wang Zhi-hong1, LU Hua-fu2

1997, 3(1):  118-128. 

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Based on the latest tectonic theories and attainable data, the present authors put forward their own views about the research of lithosphere tectonic evolution of SE China．The concepts of terrane analysis and the mode1 of tectonic facies, as two methods of regiona1 tectonic analysis rooted in plate tectonics, are harmonious. The former contributes to clarify the composite units of orogenic belts and their origin and development, while the latter constructs the regular pattern of formation and evolution of orogenic belts. A synthetical study of the two methods is an effective and practicable thinking in research of orogenic belts of China. The Precambrian crust materials n SE China are some palaeoslabs from Gondwana and their re-cycled materials rather than autochthonous, and they call not constitute a unified Cathaysia old landmass. The four stages collisions between microcontinents or terranes respresented by these plaleoslabs, occurring in late Proterozoic, early Paleozoic, early Mesozoic and late Mesozoic respectively, formed the multiple orogenic belts in SE China. Detailed analyses of the four orogenic belts indicate that the concepts of Tethyan system or/and Pacific system can not give a perfect definition for their subduction polarities and senses of tectonics, especially n the existence of flake tectonics which would complicate the corresponding relationship between subduction polarity and sense of tectonics. It has been verified by the research of southeastern Pujian 1ate Mesozoic orogenic belt. Oblique collision and strike-slip are more common collisional styles between plate boundaries and have been regarded as basic property of orogenic belts. This has been affirmed by the identification of oblique collision and strike-slip in the multiple orogenic belts of SE China and other areas all over the world. The authors conclude that the research of flake tectonics, oblique collision and strike-slip will extend the study domain of orogenic belts and offer a new approach to reconstruct the relationship between plate kinematics and collisional dynamics.