Grain size distribution of soils within the Cordillera Blanca,Peru: An indicator of basic mechanical properties for slope stability evaluation   总被引：1，自引：0，他引：1  

Jan NOVOTNY  Jan KLIME 《山地科学学报》2014,11(3):563-577

This paper presents results of a study on the mechanical properties of sandy and gravely soils within the Cordillera Blanca, Peru. The soils were divided into groups according to their origin （glacial, fluvial, or debris flow）. The grain size distribution of forty three soil samples was used to classify the soils according to the scheme of the Unified Soil Classification System （USCS）. These distributions have then been used to estimate shear strength and hydraulic properties of the soils. There are clear differences between the soils which reflect their divergent origins. The glacial soils normally fit within one of two distinctive groups according to the proportion of fines （Group A, 7%-21.5%; Group B, 21%-65%）. The estimation of shear strength at constant volume friction angle and peak shear strength of the glacial sediments with low content of fines was made using published data relating to the measured shear strength characteristics of soils with similar origins and grain size distributions. The estimated values were supported by measurements of the angle of repose taken from fourteen samples from two moraines and by shear tests on samples from one locality. The results of the grain size distribution werealso used to estimate the average hydraulic conductivity using the empirical Hazen formula which results were verified by field infiltration tests at two localities.  相似文献   

秘鲁外海鲯鳅生物学特性及资源分布初步研究     

许骆良  ;王伟杰  ;钱卫国 《广东海洋大学学报》2014,(3):5-9

根据2012年5~7月东南太平洋秘鲁外海(探捕海域在83°W~87°W、10°S~14°S)鲯鳅资源的探捕调查资料,对其生物学特性作了初步分析。结果表明:秘鲁外海鲯鳅的叉长范围为31~121cm,优势叉长为30~50cm,占57.4%;在个体大小的空间分布上,探捕海域北部比南部个体略微偏大;雌性叉长(l)与体质量(m)关系式为m=5×10-4·l2.236 2(R2=0.940 5;n=104 9),雄性为m=5×10-4l2.209 6(R2=0.958 0,n=851);雌性鲯鳅比例稍高,占55.2%。探捕海域鲯鳅鱼资源密度较高,CPUE值范围为2~23.6 kg/(人·h),平均为11.6 kg/(人·h);不同区域资源密度有所差异,其中CPUE最高的区域在84°W~86°W、12°30′S~13°30′S附近;探捕期间6月份的最高平均CPUE为16.37 kg/(人·h)。  相似文献   

Mining History: Mobilizing The Past In Struggles Over Mineral Extraction In Peru     

Matthew Himley 《Geographical review》2014,104(2):174-191

This paper examines how the past is constructed and mobilized within contemporary Peruvian mining politics. Beginning with an exploration of tensions existing within the mining industry's relationship to its history, I analyze how mining proponents have sought to both naturalize today's mining expansion by locating it within a national history of extraction, while also working to break free from certain negative aspects of the industry's past. The paper then examines how the past is remembered and invoked within the context of on‐the‐ground struggles at a large‐scale gold mine in the region of Ancash. I address the contradictory ways in which local history is constructed in these struggles and document how memories of past experiences with mining inform how area residents understand and critique the “new” mining economy. This paper underscores the need to understand the complicated, selective, and often‐contradictory ways in which the past is made present in extractive industry conflicts.  相似文献   

Consistent Distribution of Stress before Strong Earthquake from Focal Mechanisms     

Zeren Zhim  Diao Guiling  Li Zhixiong 《中国地震研究》2010,24(4):415-422

At some stage of a strong earthquake preparation,the focal mechanisms of small earthquakes have roughly the same direction with the tectonic stress field.According to this feature,we define the angle between P,B and T axis of focal mechanisms and the three stress axes of tectonic stress field as the consistency parameter a in studying the dynamic changes of stress fields in earthquake preparation areas.We mainly analyze the changes of the consistency parameter a of the MW8.3 Kuril island arc earthquake and the MW8.4 Peru earthquake.Our study shows that before the strong earthquakes,the earthquake area saw a low consistency,and the focal mechanisms of a series of small earthquakes had small differences in the directions with the tectonic stress field,which means the foreshocks were under the control of the stress field.On the other hand,a higher consistency means the focal mechanisms of their aftershocks are scattered and have big differences in the directions with the tectonic field,which indicate that the control of background stress field starts weakening.  相似文献   

基于灰色系统的西北太平洋柔鱼冬春生群资源丰度预测模型   总被引：5，自引：2，他引：3  

高雪  陈新军  余为 《海洋学报》2017,39(6):55-61

柔鱼（Ommastrephes bartramii）是西北太平洋重要的经济头足类之一,科学预测柔鱼资源丰度有利于其合理的开发和利用。研究结合1998-2008年北太平洋柔鱼生产统计数据和产卵场环境及其气候因子,使用灰色关联分析和灰色预测建模的方法,对产卵期内（1-4月）影响柔鱼冬春生群体资源丰度（CPUE）的产卵场环境以及气候指标进行分析,并建立柔鱼冬春生群体资源丰度的预报模型。结果表明,产卵期内影响柔鱼冬春生群体资源丰度的因子依次是:3月份产卵场平均海表面温度SST（average sea surface temperature）、1月份太平洋年代际震荡指数PDO（Pacific Decadal Oscillatio index）,4月份Niño3.4指标和4月份平均叶绿素浓度Chl a（average chlorophyll a concentration）。灰色预报模型分析表明,基于3月份SST、1月份PDO和4月份Chl a的GM（1,4）模型有着较好的预测效果,其预测准确率在80%以上,可用于西北太平洋柔鱼冬春群体资源丰度的预测。  相似文献   

西北太平洋环境变化对柔鱼冬春生群体资源丰度年间变化的影响   总被引：5，自引：0，他引：5  

余为  陈新军  陈长胜  张瑜 《海洋学报(英文版)》2017,36(10):48-59

The neon flying squid Ommastrephes bartramii is an economically important species in the Northwest Pacific Ocean. The life cycle of O. bartramii is highly susceptible to climatic and oceanic factors. In this study, we have examined the impacts of climate variability and local biophysical environments on the interannual variability of the abundance of the western winter-spring cohort of O. bartramii over the period of 1995–2011. The results showed that the squid had experienced alternant positive and negative Pacific Decadal Oscillation(PDO) over the past 17 years during which five El Ni?o and eight La Ni?a events occurred. The catch per unit effort(CPUE) was positively correlated with the PDO index(PDOI) at a one-year time lag. An abnormally warm temperature during the La Ni?a years over the positive PDO phase provided favorable oceanographic conditions for the habitats of O.bartramii, whereas a lower temperature on the fishing ground during the El Ni?o years over the negative PDO phase generally corresponded to a low CPUE. The same correlation was also found between CPUE and Chl a concentration anomaly. A possible explanation was proposed that the CPUE was likely related to the climateinduced variability of the large-scale circulation in the Northwest Pacific Ocean: high squid abundance often occurred in a year with a significant northward meander of the Kuroshio Current. The Kuroshio Current advected the warmer and food-rich waters into the fishing ground, and multiple meso-scale eddies arising from current instability enhanced the food retention on the fishing ground, all of which were favorable for the life stage development of the western squid stocks. Our results help better understand the potential process that the climatic and oceanographic factors affect the abundance of the winter-spring cohort of O. bartramii in the Northwest Pacific Ocean.  相似文献   

Thrust tectonics in the Andean retro-foreland basin of northern Peru: Permian inheritances and petroleum implications     

《Marine and Petroleum Geology》2017

In northern Peru, the Huallaga-Moyabamba-Marañon Subandean foreland basin system results from the interaction between thin and thick-skinned tectonics. Geophysical data and the construction of two balanced cross-sections show that this structural configuration has been controlled by Permian inheritances. A fossilized west-verging Middle Permian fold and thrust belt, which developed during the Gondwanide orogeny, has been partly reactivated by the Andean compression and controlled thick-skinned tectonics propagation. This west-verging thrust system is still active and causes the crustal and damaging seismicity of the Moyabamba region. Late Permian salt, which has sealed the Middle Permian fold and thrust belt, controlled thin-skinned tectonics propagation and the development of the must large overthrust of the Peruvian Subandean zone. The fossilized and partly reactivated Middle Permian fold and thrust belt constitutes a new petroleum play for the exploration in the northern Peruvian Subandean basins. Sub-thrust traps of the Moyabamba and Huallaga wedge-top basins are particularly attractive but stay unexplored.  相似文献   

Food web and fish stock changes in central Chile: comparing the roles of jumbo squid (Dosidicus gigas) predation,the environment,and fisheries     

《Deep Sea Research Part II: Topical Studies in Oceanography》2013

We analyzed recent food web and fish stock changes in the central Chile marine ecosystem, comparing the roles of jumbo squid (Dosidicus gigas) as predator, the environment, and fishing. To accomplish this we used food web modeling and the Ecopath with Ecosim software (EwE). The principal fish stocks have experienced wide decadal fluctuations in the past 30 years, including stock collapses of horse mackerel (Trachurus murphyi) and hake (Merluccius gayi), and there was a large influx of jumbo squid during the mid-2000s. We used two EwE models representing the food web off central Chile to test the hypothesis that predation by jumbo squid has been significant in explaining the dynamics of the main fishing resources and other species in the study area. Results indicate that predation by jumbo squid on fish stocks is lower than that of other predators (e.g. hake) and the fishery. Long-term fluctuations (1978–2004) in the biomass of the main fish stocks (as well as other components of the food web) seem to be related to fishing and to variation in primary production, rather than to predation by jumbo squid alone. Jumbo squid seems to play a role as predator rather than prey in the system, but its impacts are low when compared with the impacts of other predators and fishing. Therefore, we conclude that jumbo squid predation on its prey was not the primary force behind the collapse of important fish stocks off central Chile. Future efforts should be directed to better understanding factors that trigger sudden increases in jumbo squid abundance off central Chile, as well as modeling its trophic impacts.  相似文献   

秘鲁邦沟铁多金属矿地质特征及成矿阶段划分     

姚仲友  崔聚荣  魏文俊  董彦璞  刘君安 《地质通报》2017,36(12):2213-2220

秘鲁首都利马至查拉400km沿海成矿带赋存多处铁、铜、金矿床,铜金矿床具有IOCG(铁氧化物)型,铁矿多为矽卡岩型。邦沟铁多金属矿规模巨大,矿床位于西科迪勒拉山西部边缘的伊卡-纳斯卡拗陷附近。矿床类型既有矽卡岩特征,也具有IOCG特点。总结矿床地质特征认为,邦沟铁和多金属矿矿化存在同期不同阶段的特点,铁矿化发生在第一期,铜金硫化物矿化发生在第二期;铜金硫化物在空间上与主铁矿体异位,铜金矿有较大找矿潜力。  相似文献   

秘鲁萨卡拉铁-铜-金矿床地质特征及成因     

李汉武  刘君安  姚仲友  陈念  姚春彦 《地质通报》2017,36(12):2221-2234

萨卡拉(Cercana)铁-铜-金矿床位于秘鲁南部古近纪斑岩型铜-钼矿床成矿带西缘。通过大量的野外地质调查、遥感、物探及室内工作认为,萨卡拉矿床与该地区典型斑岩型矿床存在一定的差异,且具有铁氧化物铜金(IOCG)矿床的某些特点。分析其深部找矿潜力,指出在进行矿产勘查时应考虑从IOCG型矿床的角度出发,对其进行深入的勘查,突破目前遇到的找矿工作困境。  相似文献