检索结果-南通市图书馆

chinese Science Bulletin 2002年第13期47卷 1113-1118页

作者： zhang xiaohui, li tiesheng & PU ZhipingResearch Center of Mineral Resources Exploration,{2., chinese academy of sciences, beijing 100101, china Guangzhou institute of Geochemistry, chinese academy of sciences, Guangzhou 51 Research Center of Mineral Resources Exploration Institute of Geology and Geophysics Chinese Academy of Sciences Beijing China Guangzhou institute of Geochemistry Chinese Academy of Sciences Guangzhou China

Two ductile shear zones trending EW and NNE respectively not only controlled the tectonic framework of the northern North china, but also constrained the geody-namic background for gold mineralization in this region. Field observations and microstructural analyses reveal that the EW trending ductile shear zones are mainly contributed to dextral compressional deformation resulting from top-to-the-southeast oblique thrust shearing, whereas the NNE trending ones are genetically related to sinistral strike-slip and extensional faulting. One sample from the former yielded an 40Ar-39Ar plateau age of (2.9±4) Ma (Bi) and two samples from the latter gave 40Ar-39Ar plateau ages of (116± 2. Ma (Bi) and (12.±3) Ma (Bi). These ages provide constraints on the top-to-the-southeast oblique thrusting event occurring in Late Triassic and the sinistral extensional and strike-slip faulting event which occurred in Early Cretaceous.

关键词： 40Ar-39Ar age biotite ductile shear zone West liaoning Region.

^(40)Ar-^(39)Ar ages of the Louzidian-Dachengzi ductile shear zone near Chifeng,Inner Mongolia and their tectonic significance

在线全文

学校读者我要写书评

暂无评论

chinese Science Bulletin 2002年第15期47卷 1292-1297页

作者： zhang xiaohui, li tiesheng, PU Zhiping & WANG HuiResearch Center for Mineral Resources Exploration,{2., chinese academy of sciences, beijing 100101, china Guangzhou institute of Geochemistry, chinese academy of sciences, G Research Center for Mineral Resources Exploration Institute of Geology and Geophysics Chinese Academy of Sciences Beijing China Guangzhou institute of Geochemistry Chinese Academy of Sciences Guangzhou China

The Louzidian normal fault occurs as the eastern detachment fault of the Kalaqin metamorphic core complex. Field observations and microstructural analyses reveal that the Louzidian-Dachengzi ductile shear zone developed in its lower-plate was genetically related to sinistral strike-slips and extensional faulting. Two samples from this ductile shear zone yield 40Ar-39Ar plateau ages of 133 Ma (Bi) and 12. Ma (Kp), which are concordant with their isochron ages. The plateau age of 133 Ma (Bi) records the formation age of the ductile shear zone. The inconsistent relationship between the earlier strike-slip ductile shear zone and the later normal fault makes the Kalaqin Quasi-metamorphic core complex distinctive from Cordil-leran nietamorphic core complex. These ages provide important geochronological data for putting constraints on the formation age and genesis of such ductile shear zones.

关键词： 40Ar-39Ar age Sinistral strike-slip Louzidian-Dachengzi ductile shear zone Metamorphic core complex.

^(40)Ar/^(39)Ar dating of shear deformation of the Xianshuihe fault zone in west Sichuan and its tectonic significance

在线全文

学校读者我要写书评

暂无评论

Science china Earth sciences 2004年第9期47卷 794-803页

作者： zhang Yueqiao1, CHEN Wen2. 3 & YANG Nong1 1. institute of Geomechanics, {2. academy of Geological sciences, beijing 100081, china 2. institute of geology, {2. academy of Geological sciences, beijing 100037, china 3. institute of geology and geophysics, chinese academy of sciences, beijing 10002., china institute of Geomechanics Chinese Academy of Geological Sciences Beijing China institute of geology Chinese Academy of Geological Sciences Beijing China institute of geology and {2. Chinese Academy of Sciences Beijing China

Based on field geological survey, structural measurements and classical Ar/Ar dating of mica, biotite and K-feldspar, we obtain cooling ages for Miocene left-lateral shear along the Xianshuihe fault zone. The results document two thermal events during the sinistral shear. The early event (12.10 Ma) corresponds to rapid cooling of the Zheduoshan granitic massif from above 700℃ to below 350℃. The late event (5-3.5 Ma) corresponds to cooling of granites intruded along the eastern side of the fault zone. These dating results provide important thermochronological constraint on the timing of late Cenozoic eastward extrusion of the Chuan-Dian Block in the SE Tibetan margin.

关键词： Xianshuihe fault zone, Zheduoshan granitic massif, sinistral shear deformation, 40Ar/39Ar dating, late Cenozoic.

Principles and methods of quantitative analysis on b-axis disorder in 2.: 1 dioctahedral phyllosilicate

在线全文

学校读者我要写书评

暂无评论

chinese Science Bulletin 1997年第22期42卷 1908-1912页

作者： WANG ling and zhang Zhenyu1. Changsha {2. of Geotectonics,{2., Changsha 410013, china 2. {2. of geology,{2., beijing 10002., china Changsha institute of Geotectonics Chinese Academy of Sciences Changsha China institute of geology Chinese Academy of Sciences Beijing China

IN XRD patterns of clay minerals, a phenomenon that strong peaks often have (00l) and(hkl) (k=3n) indices and show symmetric figures can be seen commonly, while a minorityof reflection peaks (hkl) (k≠3n) are comparat... 详细信息

关键词： b-axis disorder pyrophvllile 2 phyllosilicate clay minerals dioctahedral minerals orientating structure of hy-droxyls crystal structure analysis DTA-TG.

Typical basin-fill sequences and basin migration in Yanshan, North china ——Response to Mesozoic tectonic transition

在线全文

学校读者我要写书评

暂无评论

Science china Earth sciences 2004年第2期47卷 181-192页

作者： li Zhong, liU Shaofeng, {2. Jinfang & WANG Qingchen1. institute of geology and geophysics,{2., beijing 10002., china 2. china University of Geosciences, beijing 100083, chinaCorrespondence should be addressed to li Zhong (email: lizhongd@***) institute of geology and {2. Chinese Academy of Sciences Beijing China china University of Geosciences Beijing China

Basin-fill sequences of Mesozoic typical basins in the Yanshan area, North china may be divided into four phases, reflecting lithosphere tectonic evolution from flexure (T3), flexure with weak rifting (J1+2., tectonic transition (J3), and rifting (K). Except the first phase, the other three phases all start with lava and volcaniclastic rocks, and end with thick coarse clastic rocks and/or conglomerates, showing cyclic basin development rather than simple cyclic rift mechanism and disciplinary basin-stress change from extension to compression in each phase. Prototype basin analysis, based on basin-fill sequences, paleocurrent distribution and depositional systems, shows that single basin-strike and structural-line direction controlling basin development had evidently changed from east-west to northeast in Late Jurassic in the Yanshan area, although basin group still occurred in east-west zonal distribution. Till Early Cretaceous, main structural-line strike controlling basins just turned to northeast by north in the studied area.

关键词： Yanshan, Mesozoic, basin-fill, paleocurrent, tectonic transition.

Comparison of eastern paleo-Tethyan ophiolites and its geodynamic significance--Evidence from Dur'ngoi ophiolite

在线全文

学校读者我要写书评

暂无评论

Science china Earth sciences 2004年第4期47卷 378-384页

作者： CHEN liang1,2. SUN Yong1,2. PEI Xianzhi2. Feng Tao2.& zhang Guowei2.1. Open Laboratory of Continental Dynamics, Ministry of Education, Northwest University, Xi抋n 710069,{2. 2.{2., chinese academy of sciences, beijing 10002.,{2. Open Laboratory of Continental Dynamics Ministry of Education Northwest University Xi’an China institute of geology and {2. Chinese Academy of Sciences Beijing China

Nd-Pb isotopic geochemistry of metabasalt from Dur抧goi ophiolite, Qinghai Prov-ince, NW china reveals the presence of DMM mixing with EMII components in its upper mantle source, which is comparable with present Indian MORB. Comparisons indicate that the geo-chemistry, chronology and source characteristics of Dur抧goi ophiolite coincide with Pa-leo-tethyan ophiolites from 揝anjiang?area. Together with evidences from regional geology in adjacent areas, this study proves that independent paleo-tethyan basins evolved contemporarily, the dynamics of which is attributed to the interaction of mantle plume with over-riding lithosphere.

关键词： ophiolite, Paleo-Tethys, DUPAL anomaly, Indosinian movement.

Carbon isotopic variations of Proterozoic carbonates in Jixian, Tianjin, china

在线全文

学校读者我要写书评

暂无评论

Science china Earth sciences 2004年第2期47卷 160-170页

作者： CHU Xuelei, zhang Tonggang, zhang Qirui, FENG {2.anjun & zhang Fusong1. institute of geology and geophysics, chinese academy of sciences, beijing 10002., china 2. Key Laboratory for Mineral Resources Research, chinese academy of sciences, beijing 10002., china Correspondence should be addressed to Chu Xuelei (email: xlchu@***) institute of geology and {2. Chinese Academy of Sciences Beijing China Key Laboratory for Mineral Resources Research Chinese Academy of Sciences Beijing China

Along the Proterozoic stratigraphic sections of Jixian, Tianjin, the ??13C values of carbonates are mostly negative in the Changchengian (Changcheng System), varying approximately within a range of (0±1)‰ in the Jixianian (Jixian System), and have commonly positive values of (2.2.‰ in the Qingbaikouan (Qingbaikou System). From Chuanlinggou Formation to Dahongyu Formation, i.e. from ca. 1700 Ma to 1600 Ma, the δ13C values of carbonates increase from about -3‰ to 0‰, but oscillate with large excursion in Dahongyu Formation. Two large excursions occur in the Jixianian, one in Yangzhuang Formation and the other in the third submember of Wumishan Formation overlaying. These integrated and continuous records of carbon isotope reflect secular variations of δ13C value in ancient seawater from ca. 1700 Ma to ca. 800 Ma. The increase and subsequent oscillation of seawater δ13C value occurring from the ages of ca. 1700 to ca. 1600 Ma and ＜1300 Ma may signify two correlative global tectonic events.

关键词： Proterozoic, Jixian, carbon isotope, chemostratigraphy, secular variation, global tectonic event.

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

在线全文

学校读者我要写书评

暂无评论

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,{2.,{2., beijing 10002., china 2. Graduate School of{2., beijing 100039, china) State Key Laboratory of lithospheric Evolution Institute of Geology and Geophysics Chinese Academy of Sciences Beijing 100029 China. Graduate School of chinese academy of sciences Beijing 100039 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.

The deep thermal characteristic of continental margin of the northern South china Sea

在线全文

同方期刊数据库

学校读者我要写书评

暂无评论

chinese Science Bulletin 2000年第18期45卷 1717-1722页

作者： zhang Jian & WANG Jiyang1. Graduate School, University of Science and Technology of china,{2., beijing 100039, china 2. institute of geology,{2., beijing 10002., china Graduate School University of Science and Technology of China Chinese Academy of Sciences Beijing China institute of geology Chinese Academy of Sciences Beijing China

Heat flow plays an important role in the study ot thermal structure and thermal evolutionof continental margin of the northern South china Sea. The analysis of heat flow value shows that margin heat flow in the northern South china Sea is relatively high setting, but the percentage of crustal heat flow is lower than 35% in terrestrial heat flow. The terrestrial heat flow exhibited a current of rise from the Northern Continental Margin to the Southern Central Basin. However, the proportion of crustal heat flow in terrestrial heat flow slowly dropped down in the same direction. It is suggested that the main factor causing high heat flow setting is the moving up of hot material from asthenosphere.

关键词： margin of northern South china Sea terrestrial heat flow thermal structures.

High-temperature phases of pyrophyllite and their evolutionary characteristics

在线全文

学校读者我要写书评

暂无评论

chinese Science Bulletin 1997年第2期42卷 140-144页

作者： WANG ling and zhang Zhenyu1. Changsha {2. of Geotectonics,{2., Changsha 410013, china 2. {2. of geology,{2., beijing 10002., china Changsha institute of Ceotectonics Chinese Academy of Sciences Changsha China institute of geology Chinese Academy of Sciences Beijing China

WITH the increase of heating temperature, phase of pyrophyllite will undergo a series of transformations. Former scholars have done some work in this respect; the temperature spans,however, were normally not more than 1150℃ and no relatively comprehensive results have been reported. Thus, the features of the phases from indoor temperature to melting point (1710℃±) for pyrophyllite and the entire evolutionary process of the phases are uncertain.

关键词： pyrophyllite high-temperature phase phase tranformation pyrophyllite anhydrite mullite cristobalite.