Fractional crystallization models and B–Be–Li systematics at Mt Somma-Vesuvius volcano (Southern Italy)     

Angelo Paone 《International Journal of Earth Sciences》2008,97(3):635-650

A compilation of B–Be–Li data on rocks that cover the entire eruptive history of Somma-Vesuvius is presented and interpreted in the light of evolution models for the Somma-Vesuvius rocks. Using major and trace element data, fractional crystalllization models are presented for different geochemical units. These data were used to constrain the source mineralogy of the Somma-Vesuvius rocks (ol-opx-cpx-gar-amp of 0.4-0.3-0.1-0.1-0.1), the amount of sediment added (5–10%) and the melt fraction from batch partial melting computations (0.05–0.1). From the B–Li data it is inferred that the main process responsible for the B isotopic signature is sediment recycling. However, the B–Li data show a major variation in Li abundances respect to B which is explained with Li dehydration before the fluid enriched the mantle wedge that produced the arc magmas. The Somma-Vesuvius B isotope composition is intermediate between that of the Campi Flegrei and the broad field of the Eolian Island arc. A low Be isotopes in the recent volcanic rocks can be explained as: (a) the top 1–22 m of the incoming sediment is accreted, (b) large amounts of sediment erosion, (c) a slow rate of subduction which have provoked a long magmatic history for the Vesuvius magma, (d) the sediment component takes several Myr longer than the subducting plate to reach the magma source region beneath Italy.  相似文献   

CFG桩复合地基褥垫层的合理厚度确定方法研究          下载免费PDF全文

贾瑞杰  隆威  於法明 《探矿工程》2006,33(4):5-7

在CFG桩复合地基设计中，褥垫层的厚度设计是一个重点，它是复合地基承载力能否全部发挥的关键因素之一。但其设计上基本是靠经验取值，缺少理论根据。从理论方面入手，推导了褥垫层厚度的理论计算方法，给出了最佳垫层厚度、桩土应力比的解析表达式。  相似文献   

新近沉积粉细砂层地基的试验与评价     

赵本肖  游占军 《中国煤田地质》2006,18(4):45-46,48

通过对邯郸市某车间地基的勘察．分析和探讨了新近沉积粉细砂地层的勘察手段、其物理力学性质，及其利用载荷试验确定承载力的标准取得了较为满意的结果，提出的一些分析方法，对新近沉积的粉细砂地层的勘察具有一定的借鉴作用。  相似文献   

Reliability Based Assessment of Shallow Foundations Using Mathcad     

Ahmad Shlash Alawneh  Osama K. Nusier  Ahmed Abdul-Ezel Al-Mufty 《Geotechnical and Geological Engineering》2006,24(3):637-660

A reliability based method was used to design and analyse shallow foundations using first-order Taylor series approximation. The computer program Mathcad was used to facilitate all mathematical and computional efforts. This method is an effective tool to assist the foundation designers and analyists to investigate how reliable their designs or analyses are in relation to the ultimate bearing capacity of the foundations. The approach presented in this paper provides a reliable alternative for design and analysis of shallow foundations, rather than the conventional design methods, which employs the assumptions of a specified saftey factor. Several examples were presented for design and analysis of strip footings embedded in sandy soil, and rectangular and square footings analysis embedded in clayey soils. The program input and output of each example are also presented and discussed.  相似文献   

低阻油气储层测井解释方法研究     

LI Zheng-xi 《吉林大学学报(地球科学版)》2006,(Z2)

对低阻油气储层的测井响应特征和储层物性特征进行了研究,并针对研究区域低阻储层的特点,以岩心与测井数据的相关性为依据,提出了适合地区特点的储层参数解释方法。通过应用三水导电模型,提高了低阻储层的测井解释精度。  相似文献   

胶莱盆地含金建造地球化学特征   总被引：2，自引：0，他引：2  

张竹如  聂爱国  李明琴  唐波 《地球化学》2002,31(1):78-84

胶莱盆地蓬家夼金矿床及宋家沟金矿床均赋存于下白垩统莱阳群一段含金建造中,该含金建造由砾岩、含砾砂岩、碳质泥岩及碳酸盐岩等组成,Au100.2～241.0ng/g,Ag1.50～3.73μg/g,Zn560～1021μg/g,Pb356～364μg/g,Cu60～394μg/g,As11.0～25.4μg/g,同时富硫及有机碳。含金建造K-Rb、K-Ba呈正相关,K-Sr、K-Ca不相关,Sr/Ba<1,B、V关系均显示了陆相淡水沉积特征。La/Y-REE组成显示了沉积特征。围岩、矿石及矿石中黄铁矿及磁铁矿的稀土元素分布模式相似,该含金建造是矿源层也是容矿层,是区内重要的成矿地质条件及找矿标志。  相似文献   

A mathematical hysteretic model for elastomeric isolation bearings     

J. S. Hwang  J. D. Wu  T.‐C. Pan  G. Yang 《地震工程与结构动力学》2002,31(4):771-789

An analytical model for high damping elastomeric isolation bearings is presented in this paper. The model is used to describe mathematically the damping force and restoring force of the rubber material and bearing. Ten parameters to be identified from cyclic loading tests are included in the model. The sensitivity of the ten parameters in affecting the model is examined. These ten parameters are functions of a number of influence factors on the elastomer such as the rubber compound, Mullins effect, scragging effect, frequency, temperature and axial load. In this study, however, only the Mullins effect, scragging effect, frequency and temperature are investigated. Both material tests and shaking table tests were performed to validate the proposed model. Based on the comparison between the experimental and the analytical results, it is found that the proposed analytical model is capable of predicting the shear force–displacement hysteresis very accurately for both rubber material and bearing under cyclic loading reversals. The seismic response time histories of the bearing can also be captured, using the proposed analytical model, with a practically acceptable precision. Copyright © 2002 John Wiley & Sons, Ltd.  相似文献   

含水矿物在真空下的释Ar机制:Ar-Ar热年代学面临的新问题   总被引：2，自引：0，他引：2  

马芳  穆治国 《地学前缘》2002,9(2):505-510

地质体的实际情况、激光显微探针束研究、XRD和SEM观测以及真空加热下Ar的释放特征都表明体积扩散不是含水矿物在真空加热中释放Ar的唯一机制。在低温下 ,Ar的释放主要受由缺陷引起的短程扩散和体积扩散共同作用的多途径扩散机制制约 ;而在高温下 ,由于含水矿物在真空中不够稳定 ,Ar的释放受到脱羟基、脱氢、氧化反应、分层作用等造成的晶体结构改变的强烈影响。含水矿物在高温下的氧化分解会导致矿物中原始Ar浓度梯度的均一化 ,因而无法得到真实的Ar分布剖面 ,也无法据此计算矿物的封闭温度 ,并进而可能影响到ArAr年龄坪的地质意义。  相似文献   

海拉尔盆地含油气系统   总被引：41，自引：5，他引：41  

陈守田  刘招君  崔凤林  丁玲  丁淑霞 《吉林大学学报(地球科学版)》2002,32(2):151-154

海拉尔盆地为中－新生代的断陷－坳陷型盆地，其发育演化主要经历了地壳隆起、断陷、坳陷、萎缩四个阶段。根据对成藏要素分析，确定出以凹陷为单元的三类含油气系统，各含油气系统都有各自的形成和分布规律。按其空间展布，又可划分为同期并列式、同期交叉式、异期叠合式三种组合形式。这些形式的有效组合，构成了海拉尔盆地内有利的油气聚集带。  相似文献   

Cu–Fe Bearing Zinc Sulfide from Laloki Stratabound Massive Sulfide Deposit, Papua New Guinea: Chemical Characterization     

Banda J. KULANGE  Yoshimichi KAJIWARA  Kosei KOMURO 《Resource Geology》2002,52(1):67-72

Abstract: A strange, unidentified, Cu-Fe bearing zinc sulfide occurs in the Laloki massive sulfide deposit, Papua New Guinea. The mineral is optically uniform in texture but is chemically variable and zoned even within a single grain. Copper contents vary from 0.1 up to 8.85 wt%. Iron reaches 18.31 wt% at maximum and decreases as Cu increases. It is remarkable, however, that the total Fe+Cu remains essentially unchanged between roughly 18 and 20 wt%. Zn and S are least variable, giving 45.85–47.84 wt% and 33.48–34.58 wt%, respectively. Other trace elements such as Cd and Mn are in general less than 0.2 wt%. It is strongly suggested that the mineral in question constitutes a unique Fe-Cu substitutional solid solution series belonging essentially to the Zn–Fe–Cu–S system.
The ideal chemical formula of the solid solution series can well be presented as Zn₁₀(Fe, Cu)₅S₁₅ or Zn₂(Fe, Cu)S₃, where Fe is always greater than Cu. It is intriguing that chalcopyrite blebs are recognizable restrictively only in nearby portions of the Cu-rich end member with the ideal composition close to Zn₁₀Fe₃Cu₂S_15. It has been confirmed by vacuum-sealed heating experiments that this mineral is decomposed to produce chalcopyrite and Fe-bearing normal sphalerite at temperatures below 200C. This would provide another evidence for the existence of such distinct phase as suggested here.  相似文献