排列熵应用于气候复杂性度量

云南省南部地区由于多季风系统影响和大地形作用的多样性,气候系统复杂多样。本文利用多年日气温和降水资料、依据基于长时间序列的相邻数据对比的复杂度参数——排列熵,对这种气候系统复杂性的度量效果是简单而有效的:气温熵值的空间格局反映了区域大气环流的复杂性和哀牢山山地作用的显著性;降水熵值的空间格局不仅指示了水汽来源的方向,而且反映了降水空间递变强度的区域差异。并很好的诠释了当地气候的大气环流和局地地形的双重影响效果。     

Palaeomagnetism of some Indian Rocks

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Hitherto, no palaeomagnetic data for India are available earlier than the Jurassic, 130 M.y. The remanent magnetic directions of oriented samples from one Jurassic and four pre-Cambrian rock formations in India have now been determined. One pre-Cambrian formation gave very scattered direction: the other four formations gave well-defined directions and their magnetic stability was demonstrated by a.c. and thermal demagnetization. The three pre-Cambrian results enable values of the ancient latitude and orientation of India to be estimated at 500, 600 and 750 M.y., assuming the ancient field to have been an axial dipole.
By making use of these new results, together with similar data by other workers for Australia, North America and Europe, it can be shown that, as far as the scanty data goes, the rate of drift in latitudes and orientation of the four continents has been of roughly the same magnitude throughout the period since 750 M.y.     

Polarity Reversals and Oxidation State in Rocks

The correlation between reversed polarity in rocks and strong oxidation of magnetic minerals is briefly re-examined, with especial reference to a well-documented Columbia Plateau basalt suite, recently described in this journal. The correlation appears to vary in quality from place to place and some reasons for this are suggested. Attention is particularly drawn to recent studies which suggest that for palaeomagnetic purposes there may be two groups of lavas, divisible on the basis of whether their magnetic minerals became oxidized under high or low temperature conditions.
A sizable body of opinion now holds (not necessarily correctly) that self-reversals are a negligible factor in the correlation between oxidation and reversed polarity, and that some compositional effect is most probably involved. Virtually the only known petrographic criterion which can (statistically) distinguish reversely from normally magnetized rocks is their (statistically) higher oxidation states. An obvious implication is that the water content of magmas, and perhaps of high-grade metamorphic rocks, is somehow increased during episodes of reversed polarity, so that a slightly larger proportion of rocks is more strongly oxidized.
Since motions of the Earth's core, upper mantle processes, and field reversals are apparently all related, compositional changes originating in the upper mantle could well be also related to field reversals. Alternating linear zones of more and less altered baslat recently reported from one place near the mid-Atlantic ridge might have arisen in such a way.
The importance of relating palaeomagnetic measurements to detailed mineralogical studies of magnetic minerals is again stressed.     

Computation of complete synthetic seismograms for laterally heterogeneous models using the Direct Solution Method

We use the Direct Solution Method (DSM) together with the modified operators derived by Geller & Takeuchi (1995) and Takeuchi, Geller & Cummins (1996) to compute complete synthetic seismograms and their partial derivatives for laterally heterogeneous models in spherical coordinates. The methods presented in this paper are well suited to conducting waveform inversion for 3-D Earth structure. No assumptions of weak perturbation are necessary, although such approximations greatly improve computational efficiency when their use is appropriate.
An example calculation is presented in which the toroidal wavefield is calculated for an axisymmetric model for which velocity is dependent on depth and latitude but not longitude. The wavefield calculated using the DSM agrees well with wavefronts calculated by tracing rays. To demonstrate that our algorithm is not limited to weak, aspherical perturbations to a spherically symmetric structure, we consider a model for which the latitude-dependent part of the velocity structure is very strong.     

硅质岩沉积地球化学研究现状

硅质岩是造山带中分布最为广泛的岩石类型之一,硅质岩沉积环境的确定对深海沉积作用、大陆边缘地质学及大地构造格架的厘定具有重要意义。目前,在硅质岩沉积地球化学研究方面有以下主要进展：①硅质岩沉积地球化学研究;②与蛇绿岩有关的硅质岩沉积地球化学研究;③物质来源研究;④古氧化还原条件研究;⑤硅质岩构造环境判别     

Evaluation of Interactions Between Oilfield Chemicals and Reservoir Rocks

Natural Resources Research - Sand failure and production occurs when the formation stress exceeds the strength of the formation, which is derived majorly from the natural material that cements the...