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991.
为探索满足城镇规划建设尺度(1:10000~1:50000)需要的工程地质评价方法,本文以三峡库区巴东县新城区所在的扇形斜坡区为例,系统建立了山地区域大比例尺工程地质环境质量评价的工作程序,包括地质环境要素调查、地质环境信息系统(GEGIS)建立、因子体系选定与图层编制、因子赋值与权重确定、数学模型选择、图层迭加计算、结果分析与检验、工程地质环境质量评价与区划,初步探索了地质环境功能区划的基本内容。基于MapGIS技术,采用1:16000的航摄地形图,通过系统的野外调查和分析计算,编制了巴东复杂斜坡区的高程、地形坡度、冲沟密度、山洪危险、工程地质岩组、斜坡类型、基岩埋深、三峡水库175m水位浸润区埋深、三峡水库175~145m水位变动带岩土体工程地质性质、斜坡变形或岩土应力集中区埋深、地震动参数异常和人类活动方式等12个因子图层。通过巴东复杂斜坡区工程地质环境质量计算、抽样检验和分区评价,提出了地质环境功能区划:A级区是1、2级工程地质环境质量区,面积约6.6km^2,占全区面积的36.8%,地质环境容量大或较大,这类区域可规划为城镇集中建设区;B级区是3级工程地质环境质量区,面积约5.6368km^2,占全区面积的31.52%,地质环境容量中等,这类区域可以作为林、草或休闲地和农村社区,沿江地段规划码头、港口等;C级区是4、5级工程地质环境质量区,面积约5.64km^2,占全区面积的31.5%,是历史滑坡多发区,地质环境容量较小或小,这类区域可开发为果园和城镇蔬菜基地,不宜规划为永久建筑区。  相似文献   
992.
本文在分析地震灾害特点的基础上,对开展辽宁省地震保险区划工作的目的意义、研究内容、工作思路及需要注意的问题等作了叙述,指出地震保险区划对辽宁保险业发展以及防震减灾工作有重要的促进作用。  相似文献   
993.
锡铁山铅锌矿床为海底喷流沉积为主兼后期迭加改造的矿床.研究表明,矿体元素在纵向上从盆地边缘-近边缘-盆地中心-喷流口部位,出现由低温Hg、Sr、Ba、Cu-中低温Hg、Sr、Ba、B、Ag、Au、Mn、Cu、Pb、Zn-中高温Pb、Zn、Ag、Au、Cu、Sn、Bi、As-高温Cu、Bi(Pb、Zn)的分带,并且以喷流口为中心,两侧盆地呈对称状态.矿体垂向上晕的表现为Cu、Pb、Zn、Sn、Bi、As、Au等中高温元素紧裹着矿体,Co、Ni、Cr对称地分布在两侧,Ba(Hg)呈宽缘晕如帽式样分布在矿体前缘,为一种紧裹型镜相对称的帽式结构.元素轴向分带序列为(由上至下):B-Ba-Hg-(Sr-Cr)-Ni-Cu-Zn-Au-Mo-Bi-As-Pb-Mn-Sn-Co-Ag-Sb-(Ni),前缘晕元素为Ba、B、Hg、Sr,矿体尾部元素为Co、Ni、Cr.在此基础上建立了矿床综合地球化学异常模式及找矿评价指标.  相似文献   
994.
Ab initio calculations of the beryl structure at room and higher pressures, and of its equation of state, have been performed both at the Hartree–Fock (HF) and density functional (DFT) level. In the latter case, three different hybrid HF/DFT Hamiltonians have been employed, in which the exact non-local exchange contribution increases from 20% (B3LYP Hamiltonian, indicated with the symbol F20) to 50% (F50) and 60% (F60). Within the DFT series, the equilibrium volume (V 0) increases as the HF exchange contribution decreases; with respect to the experimental datum, F20 overestimates V 0 by 2.9%, whereas F60 underestimates it by 0.9%; F50 (and HF) volume is very close to the experimental datum (error less than −0.1%). All four Hamiltonians overestimate the bulk modulus (K 0); with respect to the experimental datum (obtained in the present work) [K 0=179(1) GPa], the F20 Hamiltonian leads to the smallest error (+2.7%); the corresponding errors for the F50, F60 and HF Hamiltonians are +13.2, +16.2 and +16.3%, respectively. In the case of F20, in spite of the small error in K 0, the relatively large error in V 0 leads to an incorrect P(V) equation of state, which significantly overestimates the pressure at a given volume, compared to the experimental one at the same volume; the maximum error in the pressure range investigated is at the largest pressure (P max=26.4 GPa) and amounts to +34.8%. The corresponding errors for the F50, F60 and HF Hamiltonians are +12.9, +5.7 and +15.5%.  相似文献   
995.
K-feldspar megacrysts (Kfm) are used to investigate the magmaticevolution of the 7 Ma Monte Capanne (MC) monzogranite (Elba,Italy). Dissolution and regrowth of Kfm during magma mixingor mingling events produce indented resorption surfaces associatedwith high Ba contents. Diffusion calculations demonstrate thatKfm chemical zoning is primary. Core-to-rim variations in Ba,Rb, Sr, Li and P support magma mixing (i.e. high Ba and P andlow Rb/Sr at rims), but more complex variations require othermechanisms. In particular, we show that disequilibrium growth(related to variations in diffusion rates in the melt) may haveoccurred as a result of thermal disturbance following influxof mafic magma in the magma chamber. Initial 87Sr/86Sr ratios(ISr) (obtained by microdrilling) decrease from core to rim.Inner core analyses define a mixing trend extending towardsa high ISr–Rb/Sr melt component, whereas the outer coresand rims display a more restricted range of ISr, but a largerrange of Rb/Sr. Lower ISr at the rim of one megacryst suggestsmixing with high-K calc-alkaline mantle-derived volcanics ofsimilar age on Capraia. Trace element and isotopic profilessuggest (1) early megacryst growth in magmas contaminated bycrust and refreshed by high ISr silicic melts (as seen in theinner cores) and (2) later recharge with mafic magmas (as seenin the outer cores) followed by (3) crystal fractionation, withpossible interaction with hydrothermal fluids (as seen in therim). The model is compatible with the field occurrence of maficenclaves and xenoliths. KEY WORDS: Elba; monzogranite; K-feldspar megacrysts; zoning; magma mixing; trace element; Sr isotopes; petrogenesis  相似文献   
996.
结合中国海洋功能区划发展状况,在指出青岛海洋旅游功能区划的重要意义的基础上,从探讨青岛海洋旅游区划的依据与原则出发,通过分析海洋旅游资源地域特征和功能类型,制定了青岛海洋旅游功能区划方案,确定青岛海洋旅游功能区划体系,包括四大旅游功能类型,28个滨海旅游功能区,同时考虑到区域差异性、互补性,结合旅游发展空间定位要求,进一步提出海洋旅游资源开发次序,即南部重点海洋旅游区、西海岸次级海洋旅游区、胶州湾新兴复合海洋旅游区、东部沿海潜在旅游区。  相似文献   
997.
In southeastern Sicily, the distribution pattern of earthquake-triggered landslides is inconsistent with historically known seismic activity. In particular, historical seismicity has been stronger in the eastern sector, while earthquake-triggered landsliding is much more developed in the western sector, and this contrasts with expectations. This paper describes the patterns of seismicity and landsliding, and tackles the problem of whether greater landsliding in the western sector may be due (a) to seismicity of the eastern sector or (b) to a high-magnitude, low-recurrence seismicity generated in the western sector itself. It is statistically shown that lithostructural characteristics of rock masses and geometry of hillslopes cannot justify, either singly or jointly, greater landsliding in the western sector if triggering earthquakes are generated in the eastern sector. As a consequence, it is possible that landsliding of the western sector is due to earthquakes generated locally, but having higher magnitude and longer recurrence intervals than historically observed.  相似文献   
998.
泥石流危险性分区及其在泥石流减灾中的应用   总被引:1,自引:1,他引:1  
泥石流是一种突发性山地灾害,至今尚缺乏准确有效的预报方法。减灾工程也只能对一定规模的泥石流起到防御作用。泥石流危险性分区在泥石流减灾中具有重要作用。以泥石流运动数值模拟为基础,以数值模拟获得的流速和流深等参量为分区指标的危险性分区是泥石流危险性分区研究的重点和发展方向。其中,泥石流危险性动量和动能分区充分反映了泥石流的破坏能力,可以提供更为精确的定量化的分区结果。该类分区方法在城镇等有重要危害对象的泥石流减灾中具有广泛的应用。不仅可以应用于泥石流危险区和安全区的划定、泥石流灾害预估、泥石流临灾预案制定、泥石流抢险救灾方案制定和泥石流灾情评估等,还可以应用到山区土地利用规划、山区城镇建设规划和财产保险评估等领域,并起到防灾和减灾的作用。  相似文献   
999.
Zoning patterns of An content and Fe, Mg and Sr concentrations in plagioclase phenocrysts in andesites from Parinacota Volcano (N. Chile) reflect alternating recharge events with two chemically distinct mafic magmas. These magmas are characterized by low and high Sr contents, similar to two recent mafic flank eruptions. One end-member basaltic andesite shows large Sr enrichment and Heavy Rare Earth depletions and thus equilibrated with lower-crustal rocks at depth where plagioclase (high Sr) is unstable, and garnet (high HREE, Y) is stable. A second end-member magma is lower in Sr, Ba contents and has REE patterns typical for parent magmas elsewhere in the Central Andes.

The number of recorded recharge events increases after a catastrophic sector collapse and during the subsequent rebuilding of the stratocone. Variations of An, Fe and Mg contents and morphology of zones suggest also changes in water pressure, including decompression under water under-saturated and water-saturated conditions. Evidence for decompression is more present in post-collapse samples, suggesting that the change in the volcano dynamics involves changes in magma chamber location. This shows the importance of the cone collapse event in the volcano's magmatic evolution. We propose that both end-members are only seen at the surface of Parinacota Volcano because of the particular dynamics of this volcanic system and that similar processes might occur in other volcanic centres of the Central Volcanic Zone.  相似文献   

1000.
滇西莴中晚始新世高镁富钾火山岩中单斜辉石斑晶普遍出现正环带结构、反环带结构或韵律环带结构,少量为具绿色核部的单斜辉石(“绿核辉石”)。反环带斑晶和“绿核辉石”的幔部与正环带斑晶的核部具有相似并且相对较窄的成分范围,相对高Mg#(0.83 ~ 0.90),低TiO2(0.13 % ~ 0.29 %),Al2O3(0.73 % ~ 1.68 %)和Na2O (0.22 % ~ 0.42 %),为钾质岩浆平衡结晶的产物。反环带斑晶的核部相对低Mg#(0.77 ~ 0.84),但与反环带斑晶的幔部、正环带斑晶的核部均具有相似的Ti/Al比值(0.06 ~ 0.16);韵律环带结构斑晶的成分变化均在正、反环带斑晶的成分范围之内。莴中高镁富钾火山岩中的这些环带结构单斜辉石斑晶应来源于相似的岩浆体系,反 环带结构表明在岩浆房存在较原始岩浆对较演化岩浆再补给的岩浆混合过程,而韵律环带结构特征揭示曾多次发生这种岩浆混合过程。“绿核辉石”的核部明显低Mg# (0.50 ~ 0.74),相对富Al2O3(1.66 % ~ 3.63 %)和Na2O(0.87 % ~ 2.17 %),具有明显较低的Ti/Al比值(< 0.05)和较高的AlVI/AlIV比值(0.38 ~ 0.76),为下地壳捕虏晶 来源,证实了在滇西晚始新世富钾岩浆演化过程中存在少量地壳混染作用。  相似文献   
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