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51.
52.
对中国大陆科学钻探主孔的岩心进行了声发射测量,确定了301~1531m深度的最大主应力。并与钻孔崩落法(深度1269~1655m)测量结果进行了对比,结果表明,声发射测量所得测值基本上落在钻孔崩落法测值的趋势线上,两种方法所得结果一致,说明测量结果可信。测量结果表明科学钻探主孔地应力大小随深度增加,在浅部301m最大主应力为13.4MPa,在深部1655m为55.2MPa。随深度的增加率为0.0279MPa/m。最大主应力方向为N54°±3.3°E,且方向不随深度变化。 相似文献
53.
大别山及苏鲁地区微粒金刚石分类及其大地构造意义 总被引:3,自引:1,他引:3
1992年发现大别山首例微粒金刚石之后,又于2003年和2004年在大别山和苏鲁地区的榴辉岩薄片中和榴辉岩的人工重砂中发现了微粒金刚石。本文报道其中尚未发表的7颗,并对2颗较大的薄片中的微粒金刚石和2颗自由晶体金刚石进行拉曼光谱和红外光谱测试。研究结果表明,本区所有微粒金刚石都为IaA和IaB型金刚石的混合体。缺少Ib型金刚石,表明没有人造金刚石的混入。薄片中的金刚石大部分为石榴子石的包裹体,少数产出于颗粒之间,直径为30-180μm。自由颗粒微粒金刚石直径为400-700μm。在大别山北部,不但又一次找到了微粒金刚石,还在石榴子石中发现有单斜辉石、磷灰石和金红石的出溶。这表明北大剐不但是超高压地质体,而且可能是本区俯冲最深的地质体。 相似文献
54.
T. Geisler 《Physics and Chemistry of Minerals》2002,29(6):420-429
Raman spectroscopy and the powder diffraction technique have been used to monitor the recovery process of two partially metamict
zircons (2.6 and 4.8 × 1018
α-decays g−1) from Sri Lanka during a series of isothermal annealing experiments in the temperature range from 870 to 1622 K. These experiments
show for the first time that structural recovery in partially metamict zircon proceeds via three distinct recovery stages,
each of which occurs within a distinct time-temperature regime. Whereas the first two stages have previously been recognized
(recovery of damaged crystalline remnants and epitaxial recrystallization), the third stage has not yet been identified as
a single activated process. It is suggested that anisotropic defect annealing during the first stage at low temperatures,
where the structure recovers preferentially along the a(b) plane, produces a geometrical situation where large structural rearrangements are necessary to remove the remaining defects
inside the crystalline material. This situation is approximately reached when the amorphous domains start to recrystallize.
The reason for anisotropic annealing can be found in a different connectivity between polyhedral linkages in both directions
of the zircon lattice. High apparent activation energies, in the range of 6.4 to 7.9 eV, were determined for the third recovery
stage from the Raman data, which are interpreted to reflect large structural rearrangements (i.e. polyhedral tilting) associated
with the final recovery of the c axis. This explains the occurrence of a distinct recrystallization stage without defect annealing. Finally, it should be
mentioned that the first recovery stage is not necessarily expected to occur in less damaged zircon crystals (<∼2 × 1018
α-decays g−1), since less stable defects along the basal plane might have already been self-annealed during radiation damage accumulation
under ambient temperatures.
Received: 6 September 2001 / Accepted: 25 February 2002 相似文献
55.
G. M. da Costa E. Van San E. De Grave R. E. Vandenberghe V. Barrón L. Datas 《Physics and Chemistry of Minerals》2002,29(2):122-131
A novel method for synthesis of aluminium hematites, based upon the homogeneous precipitation of Fe and Al oxinates in various proportions, is presented. The precursor precipitates are heated in air at 700?°C. X-ray diffraction, thermal analyses, BET, FTIR, optical reflection analysis, TEM and Mössbauer spectroscopy at room temperature and 80?K of the resulting products indicate that single-phase hematites are formed with structural Al substitution of up to 10 at%. Interestingly, the particle size (>100?nm) is not substantially reduced by the Al content. Although it remains difficult to obtain a homogeneously distributed Al substitution in the final hematite, this processing line offers a unique opportunity to separate the effects of grain size and Al substitution on the Morin transition temperature (T M) of Al hematite. From the comparison between the present hematites and a series of Al-substituted hematites with lepidocrocite as precursor, it could be shown that the effect on T M, associated with a change of a factor 10 in grain size, is about 1/3 of the effect caused by a change of 10 in the degree of substitution. Finally, it is suggested that proper thermal treatments under different conditions of the same precursors are likely to produce spinel phases. 相似文献
56.
Raman spectra of diopside were collected from atmospheric pressure to 71 GPa. The pressure dependences of 22 modes were determined.
Changes occurred in the spectra at three different pressures. First, at approximately 10 GPa, the two Raman modes at 356 and
875 cm−1 disappeared, while the mode at 324 cm−1 split into two modes, diverging at this pressure with significantly different pressure shifts; second, at approximately 15
GPa, a small (1 to 2 cm−1) drop in several of the frequencies was observed accompanied by changes in the pressure dependency of some of the modes;
and third, above 55 GPa, the modes characteristic of chains of tetrahedrally coordinated silicon disappeared, while those
for octahedrally coordinated silicon appeared. The first change at 10 GPa appears to be a C2/c to C2/c transition involving a change in the Ca coordination. The third change above 55 GPa appears to be a change in the silicon
coordination. At 15 GPa, it is suggested that a change in compressional mechanism takes place.
Received: 14 November 2000 / Accepted: 9 January 2002 相似文献
57.
M. A. Bouhifd G. Gruener B. O. Mysen P. Richet 《Physics and Chemistry of Minerals》2002,29(10):655-662
Premelting effects in gehlenite (Ca2Al2SiO7) have been studied by Raman spectroscopy and calorimetry, and in gehlenite and pseudowollastonite (CaSiO3) by electrical conductivity. The enthalpy of premelting of gehlenite is 17.3 kJ mol−1 and represents 9% of the reported enthalpy of fusion, which is in the range of the reported fraction of other minerals. The
Raman and electrical conductivity experiments at high temperatures, for gehlenite and pseudowollastonite, show that the premelting
effects of both compositions are associated with enhanced dynamics of calcium atoms near the melting point. This conclusion
agrees with the results obtained for other minerals like diopside, but contrasts with those found for sodium metasilicate
in which the weaker bonding of sodium allows the silicate framework to distort near the melting temperature and deform in
such a way to prefigure the silicate entities present in the melt.
Received: 30 April 2002 / Accepted: 7 August 2002
Acknowledgements We thank Y. Linard for help with DSC measurements and two anonymous reviewers for their constructive comments. This work
has been partly supported by the EU Marie-Curie fellowship contract no. HPMF-CT-1999-00329, the CNRS-Carnegie Institution
of Washington program PICS no.192, and the NSF grants EAR-9614432 and EAR-9901886 to B.O.M. 相似文献
58.
小波分析在声发射资料处理中的初步应用 总被引:1,自引:0,他引:1
针对声发射数据分析的一些难点,把最近20年发展起来的小波技术引入声发射资料处理中,分析证明结果可靠。它在本中的应用有:(1)提取有效信息。小波强大分解(细化0能力可用来从高口音中找出有效记录,分解合成时可以去掉不理想的通道,使声发射数据更加“规则化”,有望实现到时自动判读。(2)对相互叠加的事件进行有效分离。结合全波记录,可使事件尽可能少丢失,提高声发射数量统计及b值计算等的精度。(3)使成份复杂的声发射波形数据分离成具有单一特征的波,但分解后的波究竟属于P波还是S波,甚至面波,尚难确定。 相似文献
59.
60.
Vito Ferro 《地球表面变化过程与地形》2003,28(7):707-722
Velocity measurements carried out by an acoustic doppler velocimeter (ADV) in a rectangular laboratory ?ume having a gravel bed are presented. The velocity pro?les are measured in six verticals of the channel cross‐section having an increasing distance (from 4 to 38·5 cm) from the ?ume wall. The experimental runs are carried out for ?ve different bed arrangements, characterized by different concentrations of coarser elements, and for the two conditions of small‐ and large‐scale roughness. For both hydraulic conditions, the velocity measurements are ?rst used to test the applicability of the Dean pro?le and of the logarithmic pro?le corrected by a divergence function proposed in this paper. Then, for each value of the depth sediment ratio h/d84, the non‐dimensional friction factor parameter is calculated by integration of the measured velocity distributions in the different verticals of the cross‐section. Finally a semi‐logarithmic ?ow resistance equation is empirically deduced. Copyright © 2003 John Wiley & Sons, Ltd. 相似文献