东疆哈密小堡二重热变质岩及其矿物共生分析和pTt轨迹     

周国庆 《矿物学报》2004,24(3):290-300

摘要：哈密小堡变质地体是石碳系含碳砂泥质岩，先后在315Ma~259Na经闪长岩和花岗岩体侵入导致的二重热变质作用产物，其中含红柱石铁铝榴石十字石黑云母绿泥石五种变斑晶角岩的变斑晶带状成分和结构记录了二重热变质作用特征。估算的两期热变质峰期温度压力分别为530．58oC，0．29GPa和566．06℃。0．40GPa。并获得一反时针pTt轨迹。这些特征暗示了该区岩浆作用和热变质作用与板底垫托(underplatng)和碰撞造山带因陆一陆碰撞、地壳增厚诱发的深部地壳的深熔作用有关．  相似文献   

Petrology and in situ U-Th-Pb Monazite Geochronology of Ultrahigh-Temperature Metamorphism from the Andriamena Mafic Unit, North-Central Madagascar. Significance of a Petrographical P-T Path in a Polymetamorphic Context   总被引：1，自引：0，他引：1  

GONCALVES  PHILIPPE; NICOLLET  CHRISTIAN; MONTEL  JEAN-MARC 《Journal of Petrology》2004,45(10):1923-1957

Petrological studies and electron microprobe dating of monazitefrom the mafic Andriamena unit, north–central Madagascar,indicate that an apparently continuous P–T path inferredfor Mg-granulites is actually discontinuous, resulting fromthe superposition of two distinct metamorphic events at 2·5Ga and  相似文献   

Pressure-Temperature Path Recorded in the Yangkou Garnet Peridotite, in Su-Lu Ultrahigh-pressure Metamorphic Belt, Eastern China   总被引：2，自引：0，他引：2  

YOSHIDA  DAISUKE; HIRAJIMA  TAKAO; ISHIWATARI  AKIRA 《Journal of Petrology》2004,45(6):1125-1145

Chemical variations along with changes in microstructure ofthe principal constituent minerals make it possible to identifyat least four equilibrium stages in the evolution of the Yangkougarnet peridotite in the Su-Lu ultrahigh-pressure metamorphicbelt, eastern China: Stage I—a primary garnet lherzolitestage represented by coarse-grained (a few millimeters size)porphyroclastic aluminous pyroxenes + chromian spinel ±garnet; Stage II—an ultrahigh-pressure (UHP) stage definedby fine-grained matrix phases (0·1–0·3 mmsize) of garnet + extremely low-Al orthopyroxene + high-Na clinopyroxene+ chromite; Stage III—a medium-pressure stage definedby fine-grained mineral aggregates (<0·1–0·2mm size) mainly composed of aluminous spinel + high-Al orthopyroxenein the matrix; Stage IV—an amphibolite- to greenschist-faciesstage defined by poikiloblastic amphibole. Orthopyroxene–clinopyroxenethermometry and an empirical spinel barometer give temperaturesof around 800–830°C and pressures of 1·2–2·9GPa for porphyroclasts of Stage I. Garnet–orthopyroxene,garnet–clinopyroxene and empirical spinel geothermobarometersgive relatively uniform P–T conditions for the matrixgarnet–orthopyroxene–clinopyroxene–chromiteassemblage of Stage II (  相似文献   

网络分析在“地学之窗”中的实现     

张福浩 《测绘科学》2004,29(3):26-29

介绍了“地学之窗”中的地理网络模型,以及地理网络中的各种分析方法,详细说明了优化了的Dijkstra算法,该算法充分利用了网络拓扑信息中的弧段的连接关系,避免了使用含有大量无穷值的关联矩阵,使之更适合带有拐向限制设置的最短路径算法和大量结点的实际数据。实践证明,该算法可以节约大量的内存,对于结点数比较大的网络,或带有大量拐向限制设置的网络,具有较好的适用性,在“地学之窗”软件成功地实现了设置拐向限制的最短路径分析功能。  相似文献   

我国主要水稻雄性不育系的光温特性研究   总被引：3，自引：1，他引：3  

米娜  姚克敏 《南京气象学院学报》2005,28(1):108-116

根据10个水稻雄性不育系的生育期及期间的温度和日长资料，研究了它们的光、温生态特性。用通径分析方法，分析了决定各不育系生育期变化的决策变量结果表明：晚籼及晚粳类型不育系的感光性强，中籼类型不育系的感光性弱到中等，早籼类型不育系的感光性一般都弱。10个雄性不育系中感温性弱的只占少数，感温性属弱到中强的品种占多数。除HS-3和SE21S的生育期决策变量为日长外，其他各不育系的决策变量均为温度。  相似文献   

景洪变质岩带中绿片岩特征及其构造环境     

张虎  范柱国  曾文涛 《云南地质》2005,24(4):421-426

澜沧江断裂以东的景洪变质岩带中的绿片岩分布较为广泛,其原岩为基性火山岩。主量元素表现为低碱、低钛、低FeO*/MgO、富纳、稀土配分曲线呈平坦型。微量元素比值蛛网图上,不相容元素亦具平坦型特点。显示作为绿片岩原岩的基性火山岩属大洋拉斑玄武岩。经构造环境判别,进一步证实为N型洋中脊玄武岩,其形成与原特提斯澜沧江洋密切相关。  相似文献   

中国沉积学的今后发展:若干思考与建议   总被引：4，自引：0，他引：4  

颜丹平  周美夫  宋鸿林  刘敦一  王彦斌  汪昌亮  董铁柱 《地学前缘》2005,12(2):0-0

出露于北京西山房山岩体南北两侧的官地杂岩,主要由正片麻岩、斜长角闪岩组成,局部具混合岩化特征。对官地杂岩的形成时代及出露原因一直存在很大的争议。一种观点认为官地杂岩形成时代为太古宙,出露于中生代早期的区域伸展体制下,另一种观点则认为官地杂岩是中新元古界或古生界泥质变质岩,在房山岩体侵位过程中发生接触变质作用的产物。研究表明,官地杂岩是一套正片麻岩,其中的锆石核部为岩浆成因,而外部普遍发育较窄的浅色边。SHRIMP II锆石铀铅年龄测定获得锆石的一致曲线与不一致曲线上交点年龄值为(2 521 ±20) Ma,代表了新太古代的岩浆结晶年龄,从而证明官地杂岩原岩形成于新太古代。构造分析表明,官地杂岩与上覆中元古代蓟县系至早古生代地层间为剥离断层接触关系,并为房山岩体侵位和改造,证明是一个形成于房山岩体侵位前的变质核杂岩构造。但房山岩体的侵位并未对锆石的岩浆年龄和变质年龄产生明显影响。  相似文献   

The reaction space and differentP-T evolution of Xuanhua and Miyun basic granulites in North China Craton     

Jun Ma  Renmin Wang 《中国科学D辑(英文版)》1997,40(2):166-172

The basic granulites from Xuanhua and Miyun have similar mineral assemblages but very different reactionary textures. Through comparison of the metamorphic reaction space between the basic granulites of the two areas, it is further confirmed that theP-T evolution of Xuanhua basic granulites and that of Miyun basic granulites are different. The former is of type CW-ITD. The latter is of ACW-IBC. Project supported by the National Natural Science Foundation of China and the Research Grant for Doctoral Degree from the State Education Commission of China.  相似文献   

相山地区变质基底新认识及其原岩归属的对比研究   总被引：5，自引：0，他引：5  

章邦桐  胡恭任  王湘云  陈培荣  倪琦生 《铀矿地质》1997,(1)

在相山北部首次发现十字石片岩及堇青石片岩。根据随变质作用增强而出现的新变质矿物，将相山变质岩基底划分为绢云母千枚岩带、黑云母片岩带、铁铝榴石片岩带和十字石片岩带。获得相山地区黑云母片岩－十字石片岩的Ｒｂ－Ｓｒ等时线年龄值为７１９Ｍａ，斜长角闪片岩的Ｒｂ－Ｓｒ等时线年龄值为７２６．６Ｍａ，表明相山基底变质岩属新元古期变质岩而不是加里东期变质岩。提出并采用微量元素地球化学比值聚类分析方法，确认相山地区变质岩原岩不属震旦系，而与华夏地块（古陆）的陈蔡群相当。  相似文献   

Ultra-high-pressure (UHP) marble and eclogite in the Su-Lu UHP terrane, eastern China   总被引：22，自引：0，他引：22  

T. KATO  M. ENAMI  & M. ZHAI 《Journal of Metamorphic Geology》1997,15(2):169-182

A large mass of dolomitic marble including many eclogite blocks occurs in orthogneisses of the Rongcheng area of the Su-Lu province, eastern China. The marble consists mainly of dolomite, calcite (formerly aragonite), graphite, forsterite, diopside, talc, tremolite and phlogopite. Aggregates of talc and calcite occur at the boundary between dolomite and diopside. Tremolite is a reaction product between talc and calcite. Eclogite blocks are rimmed by dark green amphibolite. The primary mineral assemblage in the core of eclogite is Na-bearing garnet (up to 0.2  wt% Na₂O), omphacitic pyroxene, clintonite and rutile. Secondary minerals are pargasitic/edenitic amphibole, plagioclase, sodic diopside, chlorite, zoisite and titanite. The peak metamorphic conditions, based on stability of the dolomite+forsterite+aragonite (now calcite)+graphite assemblage, under conditions where tremolite is unstable, are estimated at T  =610–660 °C and P =2.5–3.5  GPa (for X _{CO=0.001). A reaction between dolomite and diopside to form talc under tremolite-unstable conditions indicates a temperature decrease under ultra-high-pressure conditions (} P >2.4  GPa, X _{CO<0.0013). The formation of secondary tremolite is consistent with a nearly adiabatic pressure decrease post-dating the ultra-high-pressure metamorphism. The temperature decrease under ultra-high-pressure conditions preceding decompression may reflect the underplating of a cold slab, and the rapid decompression probably corresponds to the upwelling stage promoted by the delamination of a downwelling lithospheric root. The} P – T  conditions of the amphibolitization stage are estimated at <0.9  GPa and <460 °C, and are similar to conditions recorded by the surrounding orthogneisses.  相似文献