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11.
On Shikoku Island, which is one of the four main islands of Japan, a large number of large-scale crystalline schist landslides have been revealed and are being monitored by an observation system. Seasonal heavy rainfall is the most active meteorological factor that can threaten the stability of this kind of site-specific landslide. In this paper, on the basis of the study of the rainfall-related behavior of a typical crystalline schist landslide, the Zentoku landslide, by analyzing the precisely and continuously observed piezometric and movement data, a method was developed to quantitatively assess the effect of heavy rainfall on a large-scale landslide. The results indicated that heavy rainfall-induced landslide displacement shows good correlation with the variation of groundwater levels. Variations of groundwater level have been simulated with the use of a tank model. The simulation using this model permits the change in water levels for future rainfall events to be predicted. By combining the predicted results with the empirical relation between displacements and water levels, rainfall-induced landslide movement during extreme rainfall events can be estimated in advance. The effect of heavy rainfall on sliding behavior can be quantified in terms of the change in displacement. Thus warning information or advisories for the local residents can be provided.  相似文献   
12.
大别山超高压石榴多硅白云母片岩中钻石U-Pb年龄   总被引:2,自引:0,他引:2  
大别山超高压石榴多硅白云母片岩中钻石U-Pb年龄刘晓春(中国地质科学院地质力学研究所,北京100081)李惠民,左义成(地质矿产部天津地质矿产研究所,天津300170)关键词石榴多硅白云母片岩,U-Ph年龄,早元古代表壳岩,印支期超高压变质,大别山高...  相似文献   
13.
Long‐term weathering of a quartz chlorite schist via wetting and drying was studied under a simulated tropical climate. Cubic rock samples (15 mm × 15 mm × 15 mm) were cut from larger rocks and subjected to time‐compressed climatic conditions simulating the tropical wet season climate at the Ranger Uranium Mine in the Northern Territory, Australia. Fragmentation, moisture content and moisture uptake rate were monitored over 5000 cycles of wetting and drying. To determine the impact of climatic variables, five climatic regimes were simulated, varying water application, temperature and drying. One of the climatic regimes reproduced observed temperature and moisture variability at the Ranger Uranium Mine, but over a compressed time scale. It is shown that wetting and drying is capable of weathering quartz chlorite schist with changes expected over a real time period of decades. While wetting and drying alone does produce changes to rock morphology, the incorporation of temperature variation further enhances weathering rates. Although little fragmentation occurred in experiments, significant changes to internal pore structure were observed, which could potentially enhance other weathering mechanisms. Moisture variability is shown to lead to higher weathering rates than are observed when samples are subjected only to leaching. Finally, experiments were conducted on two rock samples from the same source having only subtle differences in mineralogy. The samples exhibited quite different weathering rates leading to the conclusion that our knowledge of the role of rock type and composition in weathering is insufficient for the accurate determination of weathering rates. Copyright © 2005 John Wiley & Sons, Ltd.  相似文献   
14.
本文研究了金厂峪金矿太古代斜长角闪岩中构造岩的特征和分布特点;根据片岩带内存在纯片岩地段、片岩带内有岩墙和两种含金脉体地段所呈现的无对称分带性、岩墙和脉体的接触关系,论述了断裂构造性质、控矿作用、热液充填期次、成矿时代;指出产于斜长角闪岩中的金矿床,并非都形成于太古代,在冀东燕山准地槽内应注意燕山期成矿作用。  相似文献   
15.
Cretaceous subduction complexes surround the southeastern margin of Sundaland in Indonesia. They are widely exposed in several localities, such as Bantimala (South Sulawesi), Karangsambung (Central Java) and Meratus (South Kalimantan).
The Meratus Complex of South Kalimantan consists mainly of mélange, chert, siliceous shale, limestone, basalt, ultramafic rocks and schists. The complex is uncomformably covered with Late Cretaceous sedimentary-volcanic formations, such as the Pitap and Haruyan Formations.
Well-preserved radiolarians were extracted from 14 samples of siliceous sedimentary rocks, and K–Ar age dating was performed on muscovite from 6 samples of schist of the Meratus Complex. The radiolarian assemblage from the chert of the complex is assigned to the early Middle Jurassic to early Late Cretaceous. The K–Ar age data from schist range from 110 Ma to 180 Ma. Three samples from the Pitap Formation, which unconformably covers the Meratus Complex, yield Cretaceous radiolarians of Cenomanian or older.
These chronological data as well as field observation and petrology yield the following constraints on the tectonic setting of the Meratus Complex.
(1) The mélange of the Meratus Complex was caused by the subduction of an oceanic plate covered by radiolarian chert ranging in age from early Middle Jurassic to late Early Cretaceous.
(2) The Haruyan Schist of 110–119 Ma was affected by metamorphism of a high pressure–low temperature type caused by oceanic plate subduction. Some of the protoliths were high alluminous continental cover or margin sediments. Intermediate pressure type metamorphic rocks of 165 and 180 Ma were discovered for the first time along the northern margin of the Haruyan Schist.
(3) The Haruyan Formation, a product of submarine volcanism in an immature island arc setting, is locally contemporaneous with the formation of the mélange of the Meratus Complex.  相似文献   
16.
青海滩间山金矿床成矿模式   总被引:1,自引:0,他引:1  
滩间山金矿床位于柴达木地块北缘,产于中元古界蓟县系万洞沟群碳质糜棱片岩和华力西晚期侵入岩中。矿床形成与柴北缘区域地壳多阶段演化和多次成矿作用有关,属多因复成矿床。矿床是在热水沉积、区域变质、热变质等预富集的基础上,与区域绿片岩相韧性剪切带的退化演化同步,经历了脆韧性、韧脆性和脆性剪切变形成矿阶段的演化并遭受华力西晚期侵入岩浆活动的叠加改造形成的。成矿物质来自容矿黑色岩系和华力西晚期侵入岩。  相似文献   
17.
湖北浠水蓝晶石铝直闪石片岩中的冠状体结构的研究   总被引:11,自引:3,他引:11  
游振东  吕学淼 《地球科学》1990,15(4):345-356
  相似文献   
18.
The basement of the central Qilian fold belt exposed along the Minhe-Ledu highway consists of psammitic schists, metabasitic rocks, and crystalline limestone. Migmatitic rocks occur sporadically among psammitic schist and metabasitic rocks. The mineral assemblage of psammitic schist is muscovite + biotite + feldspar + quartz ± tourmaline ± titanite ± sillimanite and that of metabasitic rocks is amphibole + plagioclase + biotite ± apatite ± magnetite ± pyroxene ± garnet ± quartz. The migmatitic rock consists of leucosome and restite of various volume proportions; the former consists of muscovite + alkaline feldspar + quartz ± garnet ± plagioclase while the latter is either fragments of psammitic schist or those of metabasitic rock. The crystalline limestone consists of calcite that has been partly replaced by olivine. The olivine was subsequently altered to serpentine. Weak deformations as indicated by cleavages and fractures were imposed prominently on the psammitic schists, occasionally on me  相似文献   
19.
绿片岩的力学实验表明 ,在围压 45 0MPa条件下 ,岩石约于 45 0℃开始塑性变形。温度升至 5 5 0℃时变形加剧 ,原来直径为 10mm、高 2 0mm的均匀圆柱体变成直径为 10 8mm、高 17 4mm、中部变粗的不规则柱体。这一结果为解释青藏高原的地壳加厚提供了一定的实验依据  相似文献   
20.
张魁武  邵济安 《岩石学报》1997,13(2):168-172
跃进山群出露位于佳木斯地块和那丹哈达地体之间,是完达山造山带的组成部分。它由大陆斜坡相沉积物、大洋中脊型玄武岩和洋岛型玄武岩组成,其中有镁铁-超镁铁质岩块体。它不是一个地层单位,而是与活动大陆边缘板块俯冲作用有关的蛇绿混杂岩  相似文献   
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