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91.
含油气盆地地球动力学模式 总被引:34,自引:1,他引:34
文章讨论了含油气盆地地球动力学模式,其中着重讨论了以下几个问题:(1)沉积盆地地球动力学研究的进展,使得能够提出一种根据盆地所处的板块位置和地球动力学模型进行划分的含油气盆地分类;(2)尽管我们有一些古生代克拉通盆地的地球动力学模式,但其成因机制仍缺乏令人信服的解释;(3)通过大陆内裂谷火山岩化学成分、地温场、构造变形、岩石圈结构以及区域板块构造背景综合分析,我们建立了六种大陆裂谷形成的地球动力学模式;(4)前陆盆地的形成与其周缘造山带密切相关,其地球动力学模式是大陆岩石圈对褶皱冲断带构造负载的挠曲响应; 相似文献
92.
Basins within the African sector of Gondwana contain a Late Palaeozoic to Early Mesozoic Gondwana sequence unconformably
overlying Precambrian basement in the interior and mid-Palaeozoic strata along the palaeo-Pacific margin. Small sea-board
Pacific basins form an exception in having a Carboniferous to Early Permian fill overlying Devonian metasediments and intrusives.
The Late Palaeozoic geographic and tectonic changes in the region followed four well-defined consecutive events which can
also be traced outside the study area. During the Late Devonian to Early Carboniferous period (up to 330 Ma) accretion of
microplates along the Patagonian margin of Gondwana resulted in the evolution of the Pacific basins. Thermal uplift of the
Gondwana crust and extensive erosion causing a break in the stratigraphic record characterised the period between 300 and
330 Ma. At the end of this period the Gondwana Ice Sheet was well established over the uplands. The period 260–300 Ma evidenced
the release of the Gondwana heat and thermal subsidence caused widespread basin formation. Late Carboniferous transpressive
strike-slip basins (e.g. Sierra Australes/Colorado, Karoo-Falklands, Ellsworth-Central Transantarctic Mountains) in which
thick glacial deposits accumulated, formed inboard of the palaeo-Pacific margin. In the continental interior the formation
of Zambesi-type rift and extensional strike-slip basins were controlled by large mega-shear systems, whereas rare intracratonic
thermal subsidence basins formed locally. In the Late Permian the tectonic regime changed to compressional largely due to
northwest-directed subduction along the palaeo-Pacific margin. The orogenic cycle between 240 and 260 Ma resulted in the formation
of the Gondwana fold belt and overall north–south crustal shortening with strike-slip motions and regional uplift within the
interior. The Gondwana fold belt developed along a probable weak crustal zone wedged in between the cratons and an overthickened
marginal crustal belt subject to dextral transpressive motions. Associated with the orogenic cycle was the formation of mega-shear
systems one of which (Falklands-East Africa-Tethys shear) split the supercontinent in the Permo-Triassic into a West and an
East Gondwana. By a slight clockwise rotation of East Gondwana a supradetachment basin formed along the Tethyan margin and
northward displacement of Madagascar, West Falkland and the Gondwana fold belt occurred relative to a southward motion of
Africa.
Received: 2 October 1995 / Accepted: 28 May 1996 相似文献
93.
Effects of geology and human activity on the dynamics of salt-water intrusion in three coastal aquifers in southern Spain 总被引:4,自引:0,他引:4
Mathematical modelling of salt-water intrusion processes in three aquifers on the southern coast of Spain (Río Verde, Río
Vélez and Castell de Ferro) reveals that, although all three systems are subject to the same climate and seasonal over-exploitation,
geological and human factors have very different effects on the dynamics of contamination. In the Río Verde aquifer, the most
important influence is the high volume of extractions occurring during the dry season; in Río Vélez, the intrusion is strongly
controlled by infiltration of water from the river to the aquifer, and, in the Castell de Ferro system, an intensely karstified
carbonate massif lying in contact with both the sea water and the detrital aquifer represents the main entrance point for
influx of sea water and subsequent washing of the aquifer. We have undertaken a mathematical simulation of various possible
measures to counteract intrusion, according to the specific characteristics of the process in each aquifer. These measures
include artificial recharge, use of natural recharge from the river as a hydraulic barrier, and the construction of a low-permeability
barrier.
Received: 5 December 1995 · Accepted: 12 April 1996 相似文献
94.
Thierry Rolland Stéphanie Fayolle Arlette Cazaubon Stéphane Pagnetti 《Aquatic Sciences - Research Across Boundaries》1997,59(1):57-73
In a sub-alpine river, the Asse, with an unpredictable discharge regime, chlorophyll, density and taxonomic diversity of both
drifting and periphytic communities were studied from a methodical approach. The investigations based on stamping two close
cross-sections to know their spatial distributions in a heterogeneous bed substrate showed a heterogeneous pattern of colonization
mainly influenced by hydrological variables as the current velocity, the size of the substrata (gravel-pebble-boulder). For
the drifting algae, mainly composed with benthic species temporarily unhooked to the substrata, the heterogeneity of the distribution
was reduced in fast flow which induced a mixing of the whole mass of water.
For the periphyton, some results indicated that the greatest diversity and the highest chlorophyll concentration were found
on pebble substratum where the current velocity was moderate. These results have also shown that the classical methods used
to day for investigations were inadequate for most Mediterranean rivers.
It was really difficult to estimate the water quality from classical index created for use in regular large plain rivers. 相似文献
95.
岩浆活动对油气藏形成条件的影响 总被引:13,自引:0,他引:13
结合众多实例,总结了国内外含油地中岩浆活动对油气藏形成的影响。一方面,岩浆活动所携带的高热流可以提高古地温,加速生油岩的演化,亦将使与岩浆岩毗邻的生油岩达到高成熟或过成熟, 相似文献
96.
97.
98.
阐述了大汶河流域洪涝灾害的特点,并对洪涝灾害发生的原因进行了分析,提出了预防为主、综合治理、系统防治和重点防治相结合、标本兼治的防治思路及具体防治对策. 相似文献
99.
This paper introduces and evaluates a novel method for ascertaining the grain‐size distribution of subsurface sediments that involves profoundly less sampling effort than standard methods. It is based on hybrid sampling principles previously applied to the construction of synthetic surface grain‐size distributions. The method is developed from an empirical demonstration of the approximate similarity of surface and subsurface grain‐size distributions when compared over a common range of sizes. Subsurface hybrid models are found to provide good facsimiles of grain‐size distributions de?ned using standard criteria and to yield distribution percentiles with millimetre accuracy. The technique is presented as an expedient alternative to standard methods for large, perennial gravel‐bed rivers. As this is a new technique, prudent application is advised in lieu of further investigation. Copyright © 2004 John Wiley & Sons, Ltd. 相似文献
100.
Jiongxin Xu 《地球表面变化过程与地形》2004,29(5):645-657
A comparison has been made between the hydraulic geometry of sand‐ and gravel‐bed rivers, based on data from alluvial rivers around the world. The results indicate a signi?cant difference in hydraulic geometry among sand‐ and gravel‐bed rivers with different channel patterns. On this basis, some diagrams for discrimination of meandering and braided channel patterns have been established. The relationships between channel width and water discharge, between channel depth and water discharge, between width–depth ratio and water discharge and between channel slope and water discharge can all be used for channel pattern discrimination. The relationship between channel width and channel depth can also be used for channel pattern discrimination. However, the accuracy of these relationships for channel pattern discrimination varies, and the depth–discharge relationship is a better discriminator of pattern type than the classic slope–discharge function. The cause for this difference has been explained qualitatively. To predict the development of channel patterns under different natural conditions, the pattern discriminator should be searched on the basis of independent or at least semi‐independent variables. The relationship between stream power and bed material grain size can be used to discriminate channel patterns, which shows a better result than the discriminator using the slope–discharge relationship. Copyright © 2004 John Wiley & Sons, Ltd. 相似文献