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Event Stratigraphy, Biostratigraphy and Sequence Stratigraphy of Neoproterozoic in North China

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Journal of Earth Science 1999年第2期18卷 3-11页

作者： Qiao Xiufu Gao Linzhi Gao Mai institute of geology, Chinese academy of {2. {3., beijing 100037

The aim of this study is to discuss the chronostratigraphy, catastrophic event stratigraphy, biostratigraphy and sequence stratigraphy of Neoproterozoic. In the eastern part of the North China, the Neoproterozoic consists of Qingbaikou System (1 000-800 Ma) and Sinian System (800-600 Ma). The Qingbaikou System is widely distributed over the whole area and the Sinian System only in the eastern and southern parts of the plate. In this paper, we discuss the age limit of the formations, and try to establish the Neoproterozoic chronostratigraphic frame, the ages of which are partly based on recently obtained carbonate whole rock Pb Pb isotope. Based on the event records of ancient earthquake, which are well developed in Sinian carbonates, “a vibrational liquefaction seismic sequence” in carbonate rocks is established. We propose a time correlation for the Sinian formation in eastern North China, on the bases of event records of earthquake in combination with biostratigraphy, and thus revise the traditional correlation scheme that has been used for nearly 3. years. Some biostratigraphic results were obtained in fossil microplants, megafossils and metazoans in North China. A large amount of big double layered and complex ornamented acritarchs are found in Qingbaikou and Sinian systems. On the basis of the correlation by earthquake events, the Huainan fauna is regarded as Late Sinian, probably between 700 Ma and 600 Ma. Altogether 16 depositional sequences are distinguished in the Neoproterozoic, with an average time interval of about 15-16 Ma.

关键词： catastrophic event stratigraphy biostratigraphy sequence stratigraphy Neoproterozoic North China.

Petrology of the Non-mafic UHP Metamorphic Rocks from a Drillhole in the Southern Sulu Orogenic Belt,Eastern-Central China

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Acta Geologica Sinica(English Edition) 2003年第2期77卷 173-186页

作者： ZHANG Zeming, XU Zhiqin and XU Huifeninstitute of geology, Chinese {2. of {3. sciences, 2. Baiwanzhuang Rd., beijing 100037 E-mail: zzm@***. institute of geology Chinese Academy of Geological Sciences 26 Baiwanzhuang Rd. Beijing 100037

The Drillhole ZK703.with a depth of 558 m is located in the Donghai area of the southern Sulu ultrahigh-pressure (UHP) metamorphic belt, eastern China, and penetrates typical UHP eclogites and various non-mafic rocks, including peridotite, gneiss, schist and quartzite. Their protoliths include ultramafic, mafic, intermediate, intermediate-acidic, acidic igneous rocks and sediments. These rocks are intimately interlayered, which are meters to millimeters thick with sharp and nontectonic contacts, suggesting in-situ metamorphism under UHP eclogite facies conditions. The following petrologic features indicate that the non-mafic rocks have experienced early-stage UHP metamorphism together with the eclogites: (1) phengite relics in gneisses and schists contain a high content of Si, up to 3.52.p.f.u. (per formula unit), while amphibolite-facies phengites have considerably low Si content (3.2. p.f.u.); (2. jadeite relics are found in quartzite and jadeitite; (3. various types of symplectitic coronas and pseud

关键词： UHP metamorphism non-mafic rock drillhole Dabie-Sulu orogenic belt eastern-central China

^(40)Ar/^(3.)Ar Dating of Deformation Events and Reconstruction of Exhumation of Ultrahigh-Pressure Metamorphic Rocks in Donghai, East China

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Acta Geologica Sinica(English Edition) 2003年第2期77卷 155-168页

作者： LI Jinyi, YANG Tiannan, CHEN Wen and ZHANG Sihong institute of geology, Chinese academy of {2. {3., beijing 100037E-mail: jyli@*** Chinese Acad Geol Sci Inst Geol Beijing 100037 Peoples R China

Recent investigations reveal that the ultrahigh-pressure metamorphic (UHPM) rocks in the Donghai region of East China underwent ductile and transitional ductile-brittle structural events during their exhumation. The earlier ductile deformation took place under the condition of amphibolite facies and the later transitional ductile-brittle deformation under the condition of greenschist facies. The hanging walls moved southeastward during both of these two events. The 40Ar/3.Ar dating of muscovites from muscovite-plagioclase schists in the Haizhou phosphorous mine, which are structurally overlain by UHPM rocks, yields a plateau age of 2.8.0±2.9 Ma and isochron age of 2.9.8Ma, indicating that the earlier event of the ampibolite-facies deformation probably took place about 2.0 Ma ago. The 40Ar/3.Ar dating of oriented amphiboles parallel to the movement direction of the hanging wall on a decollement plane yields a plateau age of 2.3.1±0.3.Ma and isochron age of 2.3.4±4.1 Ma, probably representing the age of the later event. The dating of pegmatitic biotites and K-feldspars near the decollement plane from the eastern Fangshan area yield plateau ages of 2.3.4±0.3.Ma, 2.3.6±0.4 Ma and 2.4.8±2.2.Ma, and isochron ages of 2.4.0±2.0 Ma, 2.0.6±3.1 Ma and 2.4.0±5.0 Ma, respectively, implying that the rocks in the studied area had not been cooled down to closing temperature of the dated biotites and K-feldspars until the beginning of the Jurassic (about 2.4 Ma). The integration of these data with previous chronological ages on the ultrahigh-pressure metamorphism lead to a new inference on the exhumation of the UHPM rocks. The UHPM rocks in the area were exhumed at the rate of 3.4 km/Ma from the mantle (about 80-100 km below the earth's surface at about 2.0 Ma) to the lower crust (at the depth of about 2.-3.km at 2.0 Ma), and at the rate of 1-2.km/Ma to the middle crust (at the depth of about 15 km at 2.3.Ma), and then at the rate of less than 1 km/Ma to the upper crust about 10 km

关键词： ultrahigh-pressure metamorphic rocks structural deformation 40Ar/3.Ar dating exhumation Donghai East China

Chengdeite-A New Mineral of Ordered Natural Iron-iridium Alloy

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Acta Geologica Sinica(English Edition) 1996年第1期70卷 27-32,108页

作者： Yu Zuxiang institute of geology, Chinese academy of {2. {3., beijing

Chengdeite occurs in chromite orebodies in dunite as well as in placers in their neighbourhood. The mineral occurs as granular aggregates in association with inaglyite and in some cases occurs as graphic intergrowths with native iridium. It is opaque with a metallic lustre, colour steel-black, streak black,HM = 5.2. VHN50=452.kg/mm2. cleavage not observed, fracture not observed, strongly magnetic. Its reflection colour is bright white with a yellowish tint. It has no internal reflection, bireflectance or pleochrism, and shows *** chemical analyses were carried out by means of the electron microprobe. The mean percentages of the data obtained in the 13.analyses ares S 0.001, Fe 7.9, Ni 0.03. Co 0.03. Cu 0.83. As 0.02. Rh 0.19, Pd 0.00, Os 0.06, Ir 88.5, Ft 2.2.and Pb 0.00. The simplified formula is Ir3.e, which requires Ir 91.17 and Fe 8.83. the total being 100.00 (% ).Five strongest lines of X-ray powder diffraction (hkl, d, I)are: 111, 2.18 (80);2.0, 1.89 (60); 2.0, 1.3. (70);3.1, 1.142.(100);2.2.1.094 (80).Through indexing of the X-ray powder diffraction data, the mineral has been determined to be cubic with Pm 3., a = 0.3.92.5)nm, V = 0.05453.m and Z = 1.

关键词： new mineral chengdeitc chromite ore

Tectonic Evolution of the Himalayan Collision Belt

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Acta Geologica Sinica(English Edition) 1997年第2期71卷 133-143页

作者： Cui Junwen institute of geology, Chinese academy of {2. {3., beijing institute of geology Chinese Academy of Geological Sciences Beijing [?]Cui Junwen Born in 193. graduated from the specialty of geological structure Department of Geology and Geography Peking University in 1965. Now he is research professor at the Institute of Geology Chinese Academy of Geological Sciences and mainly undertakes the study of deformation dynamics of the lithosphere and deep tectonics.

This paper discusses the tectonic divisions of the Himalayan collision belt anddeals with the tectonic evolution of the collision belt in the context of crustal accretion in thefront of the collision belt, deep diapirism and thermal-uplift extension and deep material flow-ing of the lithosphere-backflowing. Finally it proposes a model of the tectonic evolution-progressive intracontinental deformation model-of the Himalayan belt.

关键词： Himalayan collision belt thermal-uplift spreading thermal-uplift extension backflowing progressive intracontinental deformation at model

Geochemical Characteristics of Granitoids in the Eastern Sector of the Northern Tianshan Mountains in Xinjiang

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Acta Geologica Sinica(English Edition) 1990年第1期64卷 55-67页

作者： Wang Bixiang Li Zhaonai Zhao Guangzan Wang Fubao Zhang Shuizhe Fei Wenheng institute of geology, Chinese academy of {2. {3., beijing institute of geology Chinese Academy of Geological Sciences Beijing

The granitioids in question are located in the geosynclinal fold belt of the Northern Tianshan Mountains.The magmas are intruded into a Carboniferous marine volcanic-sedimentary rock series. forming a contempo-raneous. intermediate-basic to acid. composite intrusion. With a whole-rock Rb-Sr isochron age of 3.5.7 Ma. itis considered to be of middle Heicynian age. The granitoids have a SiO_2.content of 48-78%, a calc-alkali indexof 60 and silica-alkali indices ρ=2.2.2.4 and σ=1.5-2. From basic to acid compositions, the total REE con-tent increases from 3. to 143.ppm. δEu ranges from 0.47 to 0.86 and the Eu anomalies are negative. Thenormalized curves of REE of various rock types are very similar. These coupled with the characteristics of traceelement geochemistry show that the intrusion is an island arc-continental margin, calc-alkaline one. Theδ^(18)O values range from 5.8 to 8.9‰ and the ^(87)Sr/^(86)Sr initial ratio is 0.705. The materials of the intrusion arecomposed of a mixture of the magmas at the top of the upper mantle and in the lower crust, This indicates thatthe rocks might be consanguineous. differentiated and evolved products and possess the characteristics of Ⅰtype granites.

关键词： Geochemical Characteristics of Granitoids in the Eastern Sector of the Northern Tianshan Mountains in Xinjiang

^(40)Ar-^(3.)Ar dating and geological implication of auriferous altered rocks from the middle-deep section of Q875 gold-quartz vein in Xiaoqinling area, Henan,China

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Chinese Science Bulletin 2002年第20期47卷 1750-1755页

作者： WANG Yitian, MAO Jingwen, LU Xinxiang & YE Anwanginstitute of Mineral Resources, Chinese academy of {2. {3., beijing 100037, China institute of {2. {3., Henan Province, Zhengzhou 450053. China Lingbao Bureau of geology and Mineral institute of Mineral Resources Chinese Acad. of Geological Sciences Beijing 100037 China institute of geological {2. Henan Province Zhengzhou 450053 China Lingbao Bur. of Geol./Mineral Rsrc. Henan Province Lingbao 472500 China

The 40Ar-3.Ar age method is employed in this work to analyze the auriferous altered rocks from the middle-deep section of the Q875 gold-quartz vein in the Xiao-qinling area, and the results show that the main gold deposition of the Q875 occurred in ca. 12.-12. Ma. As a typical gold-bearing quartz vein in this gold-rich area, the age data obtained from the Q875 also constrain on the metallogenic time of the lode gold deposits developed in the same geological settings. This geochronological study supplies new evidence for further understanding the timing of gold mineralization, the genesis of gold deposits and the geodynamic settings in Xiaoqinling area.

关键词： 40Ar-3.Ar dating auriferous altered rock Q875 gold-quartz vein lode gold deposit metallogenic time Xiaoqinling.

Digital image analysis of palaeoenvironmental records and applications

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Chinese Science Bulletin 2002年第23期47卷 1957-1963,2025-2026页

作者： SUN Donghuai1,2. LIU Yu2.& TAN Ming3.. South China Sea institute of Oceanology, Chinese {2. of {2.. Guangzhou 5103.1, China 2. State Key Laboratory of Loess and Quaternary {3., Earth Environmental institute, Chinese {2. of {2., Xi’an 710075, China 3. institute of geology and Geophysics, Chinese {2. of {2., beijing 10002., China South China Sea institute of Oceanology Chinese Academy of Sciences Guangzhou China State Key Laboratory of Loess and Quaternary geology Earth Environmental Institute Chinese Academy of Sciences Xi’an China institute of geology and Geophysics Chinese Academy of Sciences Beijing China

Environmental change signals in geological or biological records are commonly reflected on their reflecting or transmitting images. These environmental signals can be extracted through digital image analysis. The analysis principle involves section line selection, color value reading and calculating environmental proxy index along the section lines, layer identification, auto-chronology and investigation of structure evolution of growth bands. On detailed illustrations of the image technique, this note provides image analyzing procedures of coral, tree-ring and stalagmite records. The environmental implications of the proxy index from image analysis are accordingly given through application demonstration of the image technique.

关键词： digital image environmental records.

Characteristics and geological significance of olivine xenocrysts in Cenozoic volcanic rocks from western Qinling

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Progress in Natural Science:Materials International 2006年第12期16卷 1300-1306页

作者： SU Benxun~ 1,2.**, ZHANG Hongfu~1, XIAO Yan~ 1,2.and ZHAO Xinmiao~ 1,2.(1. State Key Laboratory of Lithospheric Evolution, institute of geology and Geophysics, Chinese academy of {2., {3. 10002., China 2. Graduate School of Chinese academy of {2., {3. 10003., China) [a]State Key Laboratory of Lithospheric Evolution Institute of Geology and Geophysics Chinese Academy of Sciences Beijing China [b]Graduate School of Chinese academy of sciences Beijing China

Cenozoic volcanic rocks from the Haoti, Dangchang County of the western Qinling Mountains, contain a few clearly-zoned olivines. These olivines are relatively big in grain sizes and usually have cracks or broken features. Their cores have similar compositions （Mg#=90.4-91.0） to those for the peridotitic xenoliths entrained in host volcanic rocks and their rims are close to the compositions of olivine phenocrysts （Mg#=85.5-81.9）. The CaO contents in these zoned olivines are lower than 0.1%. These features demonstrate that the clearly-zoned olivines are xenocrysts and disaggregated from mantle peridotites. The zoned texture was the result of the interaction between the olivine and host magma. Available data show that the volcanic rocks would have been derived from the mantle source metasomatized by subducted hydrathermally-altered oceanic crust. The formation of these Cenozoic volcanic rocks was perhaps related to the rapid uplift of the Tibetan Plateau.

关键词： Western Qinling Dangchang Haoti Cenozoic volcanic rocks olivine xenocrysts zoned texture.