排序方式： 共有18条查询结果，搜索用时 15 毫秒
1.
通过实地考察、槽探和浅层地震探测等手段以及对地质构造和地下水超采环境的分析，详细地研究了大同铁路分局地裂缝带的三维构造特征，指出现今处于发展中的地裂缝带是由东向西扩展的，扩展速率为２６０～５２０ｍ／ａ，地裂缝带两侧的差异升降运动速率达２２．１～２４．４ｍｍ／ａ，主地裂缝带的水平拉张速率约１．１１～１１．６ｍｍ／ａ，垂直错动速率０．２～８．５７ｍｍ／ａ，左旋错动速率１．８７～３．５７ｍｍ／ａ。地裂缝带的活动方式为无震蠕滑型，扩展中的地裂缝是一种无震的地质灾害 相似文献
2.
We computed a one-dimensional (1D) velocity model and station corrections refering to the Provence region (South-eastern France) by inverting P-wave arrival times recorded on an eight-station local seismic network. Using this velocity model and the program HYPOELLIPSE (Lahr, 1989), we relocated a set of 108 local events. The quality comparison between previous earthquake locations and new relocated shows a good improvement.The obtained Minimum 1D velocity model can be used in a better-quality routine for earthquake location and represent a first step towards more detailed seismic studies in the Provence region. 相似文献
3.
(Marseille–Cassis–Bouches–du-Rhône). The salinity of the karstic submarine spring of Port-Miou has sometimes been attributed to the leaching of continental evaporites. Our recent chemical and isotopic analyses indicate a simple mixing between fresh karstic water and seawater. In the main gallery, the contamination by seawater, still present up to 2.2 km from the entrance at a depth of 147 m below the sea level, forces us to think about a general geometry that allows mixing of waters, at a great depth, in the karstic system. The measurements of the discharge of the spring indicate an excess of water compared with its supposed watershed, whereas a succinct evaluation of the aquifers of the Lower Provence indicates a deficit of discharge. Consequently, it seems possible that parts of the calcareous areas of the Lower Provence feed the springs of Port-Miou with a total catchment area of 1200 km2. This deep and large karstic system was probably installed during the Messinian period, when the important lowering of the level of the Mediterranean Sea provoked an important gradient between Provence and the seashore. To cite this article: B. Blavoux et al., C. R. Geoscience 336 (2004). 相似文献
4.
在黔东南出露的一套新元古界下江群浅变质碎屑岩中产出众多石英脉型金矿床(点),有关该类矿床的成因问题,特别是金的物质来源一直是研究的热点,因此下江群地层岩石的含金性以及元素地球化学特征也倍受关注。本文对贵州锦屏地区新元古界下江群浅变质岩及典型矿床的微量及稀土元素进行了系统测试,通过对比分析发现:下江群剖面的每个组均富集As、Ba、Zr、Ti;亏损Cr、Rb、Sr、Ta、Sc等元素,从番召组到平略组,元素组合演化呈明显相似性和继承性。含凝灰质多的番召组和清水江组地层中金含量较高,并且含金高的层位稀土含量较低,地层中Au与壳源特征的Ag、Hg、As等低温元素关系最为密切,该区金的迁移、富集可能与地层的热液活动或区域变质作用有密切的关系。围岩、地层岩石与矿石的微量元素特征及REE组成模式体现了地球化学演化上的一致性及继承性,表明该区金矿成矿物质可能主要来自于地层,而平秋金矿部分含金石英脉矿石表现出与围岩地层不同的地球化学特征,其更接近下地壳或上地幔,说明可能有部分深部流体参与成矿。 相似文献
5.
《Geodinamica Acta》2013,26(5-6):231-238
Reprocessing and interpretation of the petroleum seismic profile 81SE5b, located between the Luberon Massif and the Arc Basin, have provided new data on the Pyrenean and Alpine thrusting in western Provence. Among the principal results, it is shown that a) the repetition of the Mesozoic succession observed in the Eguilles1 borehole is due to a north-dipping south-verging thrust, and b) the Trévaresse and Aix-Eguilles thrusts are deep structures rooted in the Triassic at a depth of between 7 and 8 km. The implication of this new knowledge on the seismotectonic model of western Provence is that the front of the Alpine deformation between the Aix-en-Provence and Salon-Cavaillon fault systems, which acted as lateral ramps, lies some 7 km farther south near the northern limb of the Arc syncline. In addition, it is seen that the Alpine-Provence thrusts, considered as still active (having given rise to the 1909 earthquake with an epicentral intensity of VIII-IX), are not shallow reverse faults but correspond to major tectonic structures affecting the full thickness of the Meso-Cenozoic cover. 相似文献
6.
冀东峪耳崖和牛心山花岗岩体SHRIMP锆石U-Pb定年及其意义 总被引：18，自引：0，他引：18
侵入冀东马兰峪复背斜的前寒武岩层中的花岗岩体与区内金矿床有密切的空间关系 ,但成岩时代有争议 ,与金矿床的成因关系不明。本文采用SHRIMP定年方法对含有金矿床的峪耳岩和牛心山岩体进行了锆石U Pb年龄测定 ,获峪耳崖岩体灰白色花岗岩的2 0 6Pb 2 3 8U年龄 175± 1Ma ,肉红色花岗岩的年龄为 174± 3Ma ;牛心山花岗岩的年龄为 172± 2Ma。这 3个年龄在误差范围内可看成是同时代的产物 ,属中生代燕山期。这组年龄限定了金矿化年龄的下限 ,表明金矿化发生在中生代燕山中期后 ,但并不能精确厘定金矿化的年龄 ,因为花岗岩侵入后 ,金矿化之前 ,还有脉岩侵入 ,金矿化与花岗岩本身并无直接的成因关系。 相似文献
7.
The explanation normally given for the tectonics of Sainte-Victoire Mountain, a dozen kilometres east of Aix-en-Provence, to the north of the limestone Provence, is incorrect. To the east, the morphology of the Sainte-Victoire is subdued, whereas to the west, before the mountain breaks savagely, the morphology is that of a young mountain as appears in Alpine landscapes. This unusual aspect in the region and the large subvertical faults with vertically striated surfaces that mark the massif to the south and to the west, induce the idea of strong vertical uplifts and caste doubt on the tectonic interpretation given in 1962 by Corroy et al. According to those authors, the Sainte-Victoire is a unit of Jurassic and Cretaceous formations overthrusting 1800 m to the south conglomerates of the Late Cretaceous or Palaeocene. New observations about the conglomerate transgression over the Jurassic and Cretaceous beds, and about the faults around and on the massif do not give evidence of an overthrusting but, on the contrary, induce the idea of a uplift, perhaps still active, in the form of a ‘piano key’ inclined to the northeast. To cite this article: J. Ricour et al., C. R. Geoscience 337 (2005). 相似文献
8.
Guillaume Bernard Charles F. Boudouresque Philippe Picon 《Estuarine, Coastal and Shelf Science》2007,73(3-4):617-629
The Berre lagoon (Provence, France), one of the largest Mediterranean brackish lagoons (155 km2), was occupied, at the turn of the 20th century, by extensive Zostera meadows (Zostera marina and probably Zostera noltii; perhaps over 6000 ha). Subsequently, the lagoon was disturbed by urban and industrial pollution and, from 1966, by the diversion of the Durance River. This resulted in a 10–49-fold and 8–31-fold increase of the freshwater and silt inputs, respectively. By means of digital analysis of aerial photographs for the years 1944, 1992, 1998 and 2004, coupled with ground truth for the last three dates, we mapped the Zostera meadows. The replacement of Z. marina by Z. noltii, the latter species being already dominant in the 1970s, was completed in 1990. In parallel to this substitution, the Zostera beds underwent a dramatic decline. Their depth limit, which was (6–9) m in the early 20th century, withdrew to 3.5, 3, 1 and less than 1 m by 1944, the 1970s, 1992 and 1998, respectively. Since 1998, Zostera must be considered as functionally extinct. The total surface area of Zostera meadows was of the order of 1.5 ha in 2004. In an attempt to alleviate disturbance, the input of freshwater and silt from the Durance River was significantly reduced from the early 1980s and 1990s respectively. Similarly, from the 1970s to the 1990s, urban and domestic pollution was drastically reduced. Despite these steps, Zostera meadows continued to shrink to near extinction. The lagoon has shifted from a system dominated by seagrass beds to a system with bare silt bottoms, which now occupy most of the lagoon. The reasons could be, in addition to continuing nutrient inputs, the resuspension of silt, no longer trapped under the seagrass canopy, during wind episodes, which are frequent in the area, and/or the release of nutrients from the bare silt habitat, which would constitute an indication of a possible hysteresis of the system. However, since 2000, the establishment of the mussel Mytilus galloprovincialis, a drop in turbidity and a slight, inconspicuous progression of Z. noltii could be the harbinger of a reverse shift of the system. 相似文献
9.
10.
RésuméLe but de la présente étude est de caractériser la déformation récente subie par la Provence occidentale, située entre la nappe de Digne à l’est et la faille de Nîmes à l’ouest. Dans un premier temps, la déformation subie par un marqueur sédimentaire qui est à la fois le plus récent possible et le plus uniformément représenté dans la zone étudiée est considérée. Ce marqueur sédimentaire est le Miocène. La caractérisation de la déformation passe par l’étude de la localisation de celle-ci et donc par l’identification des structures actives responsables de la déformation du Miocène. Ces caractéristiques permettent d’estimer la quantité de raccourcissement total accumulé lors des derniers 20 millions d’années. Dans un deuxième temps, on distingue la part de la déformation postMiocène de cette déformation totale. Les marqueurs utilisés sont des surfaces et des objets géomorphologiques repères. Dans ce travail, nous montrons que la déformation en Provence a été de faible importance entre le Miocène et factuel et qu’elle est surtout produite au cours du Miocène. En conséquence, la déformation récente à actuelle est très difficile à localiser et à caractériser. 11 n’y a pas eu de déplacements post Miocène importants de part et d’autre de la faille de la Durance, pas plus d’ailleurs que le long de toutes les discontinuités majeures du domaine étudié. © 2000 Éditions scientifiques et médicales Elsevier SAS 相似文献