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

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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, chinese {2. of Geological sciences, beijing 100081, china 2. Institute of geology, chinese {2. of Geological sciences, beijing 100037, china 3. Institute of geology and Geophysics, chinese academy of sciences, beijing 100029. china Institute of Geomechanics Chinese Academy of Geological Sciences Beijing 100081 China Institute of geology Chinese Academy of Geological Sciences Beijing 100037 China Institute of geology and Geophysics Chinese Academy of Sciences Beijing 100029 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.

Uncertainty in magnetic activity indices

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Science china(Technological sciences) 2008年第10期51卷 1659-1664页

作者： XU WenYao Institute of geology and Geophysics, chinese academy of sciences,{2. Institute of geology and Geophysics Chinese Academy of Sciences Beijing 100029 China

Magnetic activity indices are widely used in theoretical studies of solar-terrestrial coupling and space weather prediction. However, the indices suffer from various uncertainties, which limit their application and even mislead to incorrect conclu-sion. In this paper we analyze three most popular indices, Kp, AE and Dst. Three categories of uncertainties in magnetic indices are discussed: "data uncertainty" originating from inadequate data processing, "station uncertainty" caused by in-complete station covering, and "physical uncertainty" stemming from unclear physical mechanism. A comparison between magnetic disturbances and related indices indicate that the residual Sq will cause an uncertainty of 1―2.in K meas-urement, the uncertainty in saturated AE is as much as 50%, and the uncertainty in Dst index caused by the partial ring currents is about a half of the partial ring cur-rent.

关键词： magnetic activity indices Kp AE Dst solar-terrestrial coupling space weather

Landscape evolution and palaeoclimate in the deserts of northwestern china,with a special reference to Badain Jaran and Taklamakan

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chinese Science Bulletin 2001年第S1期46卷 6-11页

作者： yang xiaopinginstitute of {2. and Geophysics, chinese academy of sciences, beijing 100029. china (e-mail: xpyang@public2.east. ***) 1. Institute of geology and Geophysics Chinese Academy of Sciences 100029 Beijing China

A comparative study of geomorphologic landscapes in the Badain Jaran Desert and Taklamakan Desert was made on the basis of field investigations, thermolumi-niscence and radiocarbon dating as well as analysis of sand grain texture. The sand seas of the Badain Jaran Desert differ greatly from that of the Taklamakan Desert in terms of dune morphology, interdune relief, dune stratigraphy and sand sources. The thermoluminiscence ages of the dunes suggest that the basic configuration of the megadunes in the Badain Jaran Desert has not changed at least since Middle Holocene. There were periods of more humid environment during the last glaciation and Holocene in both deserts, but events of higher precipitation in the Badain Jaran Desert were more frequent than in the Taklamakan. In both desert areas, aeolian processes have been intensified during the last 2.00 a.

关键词： desert sand seas palaeoclimate landscape northwestern china.

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

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

作者： WANG Ling and ZHANG Zhenyu1. Changsha Institute of Geotectonics, chinese academy of sciences, Changsha 410013, china 2. Institute of {2., chinese academy of sciences, beijing 100029. 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.

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

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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 100029. 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.

Mineralogy and crystal structure determination of Mg-fillowite

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Science china Earth sciences 2005年第5期48卷 635-646页

作者： MA Zhesheng 1 , SHI Nicheng 1 & YE Danian 2.1. china University of Geosciences, {2. 100083, china 2. Institute of geology, chinese academy of sciences, beijing 100029. china 1. china University of Geosciences 100083 Beijing China 2. Institute of geology Chinese Academy of Sciences 100029 Beijing China

Accurate crystal structure determination of complex phosphate Mg-fillowite ? Na2.a(Mn4Mg2.e)7[PO4]6 has been finished. Mg-fillowite occurs in muscovite-pegmatite in the Altay area, Xinjiang, china. It is of the trigonal lattice, with space group R-3, unit cell a=1.5143(3) nm, c=4.3191(2. nm, V=8.5736 nm3, Z = 18. The R-factor of the determination accuracy is R (I > 2. ( I )) = 0.0776. The cationic polyhedra consist of two kinds of structural units: compound col- umn and screw column. In three-dimensional space, they are linked with each other through corner sharing or edge sharing to build the entire structure. There are 45 atoms in an asymmetric unit and 72. atoms in a unit cell. In terms of types and connection manners of the coordination polyhedra, the degree of complicity is rarely seen in all mineral crystal structures. Study of such a structure is significant for the classification of phosphate and the building rule of coordination polyhedra in a complex crystal structure.

关键词： Mg-fillowite, complex phosphate, crystal structure, coordination polyhedron.

Reinterpretation of the Guangxian Orogeny

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chinese Science Bulletin 2000年第13期45卷 1244-1248页

作者： WU HaoruoInstitute of geology and Geophysics, chinese academy of sciences,{2. Institute of geology and Geophysics Chinese Academy of Sciences Beijing China

The Guangxian Orogeny, as an important concept on geology of South china, was created 70 years ago. It is generally regarded as an erogenic movement caused by the convergence of the Cathaysian and {2.tze blocks at the end of Silurian. Based on the recent progress of the geological research on Guangxi and adjacent areas, western Guangxi and Liuzhou-Heshan area of central Guangxi may belong to a stable block of Early Paleozoic. The Guangxian Orogeny originated from the northward translation of the Yunkai Block on its south at the end of Cambrian, and formed the Damingshan-Dayaoshan fold belt between the two blocks. It was possibly related with the Late Pan-African Orogeny. The convergence of the Cathaysian and {2.tze blocks occurred in Late Ordovician to Early Silurian and mainly had effect on Hunan and Jiangxi provinces. The term 'Chongyu Orogeny' may be suitable for it. At the end of Silurian orogenic movement did not occur in this area.

关键词： South china tectonics Paleozoic Guangxian Orogeny Yunan Orogeny Chongyu Orogeny.

Compositions of heavy minerals in Northeastern china sandlands and provenance analysis

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Science china Earth sciences 2007年第11期50卷 1715-1723页

作者： XIE Jing1,2.& DING ZhongLi1 1 Institute of geology and Geophysics, chinese academy of sciences,{2. 2.Graduate University of chinese academy of sciences, beijing 100049, china 1. Institute of geology and Geophysics Chinese Academy of Sciences Beijing 100029 China 2. Graduate University of chinese academy of sciences Beijing 100049 China

Sand samples deposited since the Last Glacial Maximum (LGM) from the Hulun Buir, Horqin and Otin-dag sandlands were measured for their assemblages of heavy minerals and chemical compositions of detrital garnets and tourmalines. Heavy mineral assemblages of these three sandlands consist mainly of garnet, ilmenite, epidote and minor amphibole and magnetite. Garnets consist mainly of high Mg type-A ones (58% on average), and minor type-B ones. Toumalines are mainly composed of Mg-rich and minor Fe-rich ones. Compared with those of central-southern Mongolia and central Tarim, these three sandlands are derived from the Phanerozoic rocks of the Central Asian Orogenic Belt and the Archean and Paleoprotorozoic basement rocks of the North china Craton. Our results provide direct evidence that the present-day sands may be reworked from LGM ones. Differences of heavy mineral composi-tions occur between the samples of the three sandlands and Taklimakan Desert, indicating that the material of the western arid regions contributes little to the eastern sandlands.

关键词： heavy minerals,provenance,Northeastern china,garnet,tourmaline

High-temperature phases of pyrophyllite and their evolutionary characteristics

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

作者： WANG Ling and ZHANG Zhenyu1. Changsha Institute of Geotectonics, chinese academy of sciences, Changsha 410013, china 2. Institute of {2., chinese academy of sciences, beijing 100029. 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.