Formation Depth of Coesite-Bearing Eclogite, Dabie UHPM Zone, China     

Lü Guxian 《中国地质大学学报(英文版)》2004,15(2):206-215

The plastic deformation of garnet in coesite-bearing eclogite,quartz eclogite and garnet amphibolite of the UHPM complex in Yingshan County in the Dabie Mountains has been studied. The stress generated by the strong tectonic movement was an important component of the total pressure that resulted in the formation of the eclogite in the Dabie UHPM zone. The three-dimensional tectonic principal stresses and additional tectonic stress-induced hydrostatic pressure ［ps=(σ1 σ2 σ3)/3］ are reconstructed according to the differential stress and the strain ratio(α) of the garnet in the minor coesite-bearing eclogite of the Yingshan County. Then the gravity-induced hydrostatic pressure(pg) is calculated following the equation p minus ps,where p is estimated to be 2.8 Gpa based on the quartz-coesite geobarmeter. Therefore,the thickness of the rock column overlying the coesite-bearing eclogite in the Ying-shan County is determined ≥32 km. This estimation,significantly different from ≥100 km,the previous one obtained solely based on the weight/specific weight ratio(W/SW),offers a proper explanation for the puzzle that no tracer of the addition of mantle-derived material has been found in the Dabie UHPM zone during the process of UHPM,although a number of researchers claim that this process took place at the depth of the mantle(≥100 km). It is concluded that attention should be paid to the additional tectonic stress-induced hydrostatic pressure in the study of UHPM zones.  相似文献   

辽宁北票早白垩世具真正两性花的始花古果（新种）     

季强  李洪起  L.MichelleBOWE  刘玉生  DavidWinshipTAYLOR 《地质学报》2004,78(4):541

被子植物起源问题被达尔文称为一个厌恶之谜，至今尚未解决。根据现代和化石植物的形态学研究，最早的被子植物被认为像尼藤类那样在两性生殖枝上有苞片和次生生殖枝(假花说／花序说)或像本内苏铁那样在两性生殖枝上有苞片和生殖孢片(真花说)。最近基因分子学研究结果认为尼藤类与松柏类最接近，从而间接地反对假花说。基因分子学研究结果还假定睡莲、八角等四科为基底被子植物，而这些植物的花和真花说所期盼的一致。孙革等人(1998，200l，2002)发现于辽西的辽宁古果和中华古果的两性生殖枝上具有簇生的雄蕊和心皮，其簇生小柄上因没有孢片被解释成花件，而整个两性枝条则被解释成具多重花件的两性花(相当于真花)。然后孙革等人(2002)将古果的17个形态特征并入具有108植物形态特征和1628植  相似文献   

北祁连东部两类Ⅰ型花岗岩定年及其地质意义   总被引：21，自引：7，他引：21  

吴才来杨经绥  杨宏仪史仁灯陈松永  郑秋光Joseph L.WOODEN 《岩石学报》2004,20(3):425-432

北祁连东部早古生代地层中产出两种特征不同的I型花岗岩类,其一以井子川岩体为代表,暗色矿物以角闪石为主,稀土总量为90×10~(-6)～106×10~(-6),轻重稀土比值小于8,锆石的SHRIMP年龄为464±15Ma,岩体形成的构造环境类似于岛弧;其二是以黄羊河岩体为代表,暗色矿物以黑云母为主,稀土总量为214×10~(-6)～250×10~(-6),轻重稀土比值大于8,锆石的LA-ICP-MS年龄为383±6 Ma,岩体形成于碰撞后环境。  相似文献   

Foreword     

Lü Guxian 《中国地质大学学报(英文版)》2004,15(2)

Since the discovery of a lot of eclogites with coesite and diamond inclusions related to the continent-continent collision-orogeny environment, the ultrahigh-pressure metamorphism (UHPM) in the Dabie-Sulu has aroused great interest in geologists. Experimental studies have proved that such minerals as diamond, coesite and omphacite etc. formed at pressures 2-5 GPa (and corresponding temperatures). However, it does not mean that by the formation pressure we can directly determine that the metamorphic rocks are the products of a deep-seated subducting plate downward to depths of 100-200 km and then returning to the surface. The calculation method of P/SW (depth=pressure/specific gravity), i.e. the formula of pressure=depth×specific gravity, needs to be thought about again.  相似文献   

加强人影工作 减缓气候变化给人类造成的灾害   总被引：1，自引：0，他引：1  

瓦黑提·阿扎买提 《沙漠与绿洲气象(新疆气象)》2003,26(2):45-46

1气候变化及其对人类的影响气候系统是包括大气、海洋、陆地、冰雪以及生物圈在内的庞大系统。引起气候系统变化的原因有多种,概括起来可分为自然的气候波动和人类活动的影响两大类。气候波动主要包括太阳辐射的变化以及火山爆发等。人类活动主要包括人类燃烧化石燃料、毁林等引起的大气中二氧化碳等温室气体浓度的增加,以及陆面覆盖和土地利用的变化等等。在气候系统中没有提到人类,但从19世纪末开始,人类活动已经成为气候变化的重要原因。人类对气候无意识的影响是值得注意的新的因子,正因为这个新因子的出现,打破了原有各个因子之间的平…  相似文献   

Study on the Relationship Between Recent Crustal Deformation and the Temporal-Spatial Distribution of Strong Earthquakes ( Ms ≥6.0) in the Sichuan-Yunnan Region     

Li Tieming  Deng Zhihui  Lü Yipei 《中国地震研究》2003,17(4):324-341

Analysis of deformation data measured across the faults, regional vertical deformation data and GPS measurements in the Sichuan-Yunnan region made since the 1980s permitted us to conclude that the crustal deformation in the region during this period of time was relatively weak and caused the occurrence of earthquakes (Ms≥6.0), which were not distributed along the major boundary active faults in the region after the 1981 I)awu Ms 6.9 earthquake and that the seismic activity is characterized by quasi-clockwise migration. Thus, it follows that earthquake prediction research should be focused on the central part of the Sichuan-Yunnan region in the coming years. Finally, a concept of temporal division of the region into active blocks is suggested and the preliminary result of the division is given in the paper.  相似文献   

中国农田的温室气体排放   总被引：70，自引：2，他引：70  

李长生  肖向明  S.Frolking  B·Moore Ⅲ  W.Salas  邱建军  张宇  庄亚辉  王效科  戴昭华  刘纪远  秦小光  廖柏寒  R.Sass 《第四纪研究》2003,23(5):493-503

中国是一个农业大国,拥有约1.33百万平方公里的农田。这些田地的种植、翻耕、施肥、灌溉等管理措施不仅长期改变着农田生态系统中的化学元素循环,而且给全球气候变化带来影响。农业生态系统对全球变化的影响主要是通过改变3种温室气体,即二氧化碳(CO₂)、甲烷(CH4)和氧化亚氮(N₂O)在土壤-大气界面的交换而实现的。为了分析多种因素(如气候、土壤质地、农作物品种及各种农田经营管理措施等)对农业土壤释放CO_22222222  相似文献   

天然气水合物地层钻井时井内温度特征的分析研究     

汤凤林  张生德  蒋国盛  Б·Б·Кудряшов  吴翔  窦斌  高辉 《煤田地质与勘探》2003,31(2):58-60

根据热交换原理，提出了井内温度规程的数学模型，按照这个模型可以计算出井内任何时间、任何深度的温度。以冷却空气作为冲洗介质为例，给出了冷却空气洗井钻进时井内温度的简化计算公式和代表性关系曲线，按照这些计算公式和关系曲线可以计算出和看出空气洗井时井内任何时间、任何深度的温度。根据计算和研究的结果，指出了为了保证在冻土中进行正常钻井，从外环状空间内返回的冲洗介质的温度不宜高于0℃，并提出了相应的建议。  相似文献   

渭干河流域水资源及其水文特征分析   总被引：6，自引：0，他引：6  

满苏尔·沙比提  玉素甫江·如素力  阿布拉江·苏来曼 《山地学报》2003,21(2):195-200

渭干河是新疆11大河之一，是渭干河一库车河三角洲绿洲的塑造者，该绿洲的生存和发展与渭干河水资源的变化趋势有密切关系。本文根据渭干河流域各水文站历年水文统计资料及近几年来实际水文调查，通过流域概况、气温、蒸发、降水、冰川、补给、年内和年际变化、泥沙、冰倩、水质、地下水资源等方面的分析和论述渭干河多年来的水资源及水文特征变化规律，试图查清渭干河流域水资源量的收支情况。  相似文献   

IMPORTANCE OF HYDROLOGY, SOIL AND VEGETATIONIN WETLAND RESEARCH     

LIU Xiao-bing　Elizabeth J.Johnson　Peter L.M.Veneman　XING Baos-han 《湿地科学》2003,1(2):128-135