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971.
The Albian–Maastrichtian seismic horizon analysis in central Tunisia (Gafsa–Sidi Bouzid area) using the reflection seismic sections calibrated to the well data, shows buried structures with deposit distributions and sedimentation geometries varying from the depressive to uplifted zones. Pinch outs, unconformities and hiatuses recognized on the folded high structures are caused by reactivation of the bordering faults. The Turonian–Maastrichtian unconformities correspond to the palaeogeographic limits that outline the Kasserine Islets and correspond to the N120, N180 major wrench-salt-intruded corridors and associated N90, N60 strike-slip faults. Formation of the different structures and evolution of the basins and platforms were controlled by conjugate dextral and sinistral strike-slip movements. These structures allow new palaeogeographic limits of the Kasserine Islets to be identified. To cite this article: T. Zouaghi et al., C. R. Geoscience 337 (2005). 相似文献
972.
Michel Durand-Delga Marie-José Fondecave-Wallez Philippe Rossi 《Comptes Rendus Geoscience》2005,337(12):1084-1095
The Jurassic N-MORB ophiolites of the Pineto Unit, which were unaffected by Alpine metamorphism, can be compared to the Apennine ophiolites. They are, however, distinguished by their cover rocks that include a silico-clastic flysch that we have dated as Albian–Cenomanian. Clastic deposits of the same type, but coarser grained, are known from the normal cover rocks of the Balagne Nappe E-MORB ophiolites, originally located on a thinned continental crust and/or near a continental margin. The Pineto Unit thus indicates that the detrital input of continental material was able to extend to a domain of clearly oceanic character in the Ligurian palaeo-ocean. To cite this article: M. Durand-Delga et al., C. R. Geoscience 337 (2005). 相似文献
973.
叙述一种新的大应变检测单桩竖向承载力的方法. 用重锤或小型火箭筒冲击桩顶,用检波器记录振波图. 引入应变(变形力)的高次项,从理论上证明当为大位移大应变, 即桩相对于土体产生整体滑动时,位移、速度和加速度则不能经过简单积分加速度和微分速度得到,即它们为非线性关系. 由此导出:通过波列振幅计算力(P)和位移(S),并作(动态)P-S曲线、确定屈服点,进而阐述确定单桩竖向承载力的方法,并利用静载荷试验检验动测结果和确定动静P(Q)S曲线的相关常数. 相似文献
974.
A linear relationship exists between the mean volume of garnet porphyroblasts and the squared inverse of mean matrix grain diameter for six samples of garnetiferous mica quartzite with identical thermal histories and similar mineralogy and modes. This relationship accords with theoretical predictions of the dependence of intergranular diffusive fluxes on the volume fraction of grain edges that function as diffusional pathways during porphyroblast growth. The impact of matrix grain size is large: compared to a rock with a 1‐mm matrix, a rock with a 10‐μm matrix would experience rates of diffusion‐controlled porphyroblast growth that are 10 000 times faster, and characteristic length scales for chemical equilibration that are 100 times larger. Precursor grain sizes may therefore exert a major influence on crystallization kinetics. If matrix coarsening occurs during prograde reaction, a decrease in the volume fraction of diffusional pathways will tend to counteract the exponential thermal increase in diffusive fluxes. The impact of such matrix grain growth, although difficult to assess without firm knowledge of coarsening rates in polymineralic aggregates, might be significant for matrices finer than c. 100 μm at temperatures above c. 500–600 °C, but is likely negligible for coarser grain sizes and lower temperatures. 相似文献
975.
976.
977.
钢管高性能混凝土压弯构件滞回性能试验研究 总被引:2,自引:1,他引:2
考虑钢材强度、混凝土强度、轴压比等参数,进行了18个钢管高性能混凝土试件的试验,分析在往复荷载作用下钢管高性能混凝土荷载-位移关系曲线的特点、构件的轴向变形和抗弯刚度退化情况,并初步探讨往复荷载作用下的钢管高性能混凝土压弯构件承载力。 相似文献
978.
Ultrahigh pressure (>7 GPa) gneissic K-feldspar (-bearing) garnet clinopyroxenite in the Altyn Tagh, NW China: Evi- dence from clinopyroxene exsolution in garnet 总被引:13,自引:0,他引:13
LIU Liang CHEN Danling ZHANG Anda SUN Yong WANG Yan YANG Jiaxi & LUO Jinhai . Key Laboratory of Continental Dynamics of the Ministry of Education of China Northwest University Xi’an China . College of Earth Science Land Resources Chang’an University Xi’an China . The Laboratory of Orogen Basin of the Ministry of Education Peking University Beijing China 《中国科学D辑(英文版)》2005,48(7)
Since the ultra-high pressure metamorphic rocks with coesite and diamond indicators,which are formed under the condition of deep-subduction of continental crust,have been recognized[1―4],exsolution structures of the ultra-high pressure minerals such as pyroxene,olivine,garnet and sphene in the various kinds of rocks have attracted the great interests and attention of many researchers[5―18].Some exsolution structures,such as clinopyroxene+rutile+apatite[13]or quartz+rutile+apatite[15]exsolutio… 相似文献
979.
U-Th-Pb副矿物的原地原位测年微束分析方法比较与微区晶体化学研究 总被引:5,自引:2,他引:5
系统地对比分析了各种微束分析技术在原地原位测年中的优势和局限性,并对近年发展的微区原位化学测年技术(EPMA)和质子激发X射线微探针分析技术(μ-PIXE)进行了探讨.阐明了矿物微区晶体化学研究的各种方法及其对实现精确原地原位测年的重要性.介绍了北大别黄土岭麻粒岩锆石测定点的晶体化学特征,应用激光剥蚀微探针-感应耦合等离子体质谱(LAM-ICPMS)技术对其进行了锆石的U-Pb表面年龄的测定,结果表明该岩石的麻粒岩相变质发生在2.050 Ga前,锆石来源为多源区. 相似文献
980.
通过对“CM桩复合地基”(以下简称CM地基 )承载力试验结果的分析 ,获得了一些有益的结论 ,对其在徐州地区的推广和应用提供参考。 相似文献