黔西北普宜地区下三叠统嘉陵江组沉凝灰岩锆石LA-ICP-MS U-Pb年龄、微量元素特征及其地质意义

早三叠世时期频繁的火山事件是导致全球性气候和海洋环境异常的主要原因,前人对早三叠世重要界线时期的火山事件地层开展了大量研究,但对典型界线时期以外的其他火山事件地层却鲜有报道.本文以上扬子西南普宜地区嘉陵江组两件沉凝灰岩为研究对象开展了岩石学、岩相学、锆石年代学及微量元素组合特征等方面的研究.沉凝灰岩样品具有典型岩浆锆石...     

内蒙古迪彦钦阿木斑岩钼矿床绿泥石和绿帘石矿物化学特征及其成矿指示意义

迪彦钦阿木矿床位于大兴安岭中段二连浩特-东乌旗多金属成矿带,是区内新近发现的一个超大型斑岩钼矿床.为了厘清蚀变矿物的成分对找矿的指示意义,文章运用电子探针和LA-ICP-MS对迪彦钦阿木矿床青磐岩化带绿帘石亚带的绿泥石和绿帘石的主微量元素成分进行了分析.电子探针数据表明,这些绿泥石属于铁斜绿泥石(辉绿泥石).绿泥石四面...     

Metamorphism of ultrahigh‐pressure eclogites from the Kebuerte Valley,South Tianshan,NW China: phase equilibria and P–T path

Eclogites from the Kebuerte Valley, Chinese South Tianshan, consist of garnet, omphacite, phengite, paragonite, glaucophane, hornblendic amphibole, epidote, quartz and accessory rutile, titanite, apatite and carbonate minerals with occasional presence of coesite or quartz pseudomorphs after coesite. The eclogites are grouped into two: type I contains porphyroblastic garnet, epidote, paragonite and glaucophane in a matrix dominated by omphacite where the proportion of omphacite and garnet is >50 vol.%; and type II contains porphyroblastic epidote in a matrix consisting mainly of fine‐grained garnet, omphacite and glaucophane where the proportion of omphacite and garnet is <50 vol.%. Garnet in both types of eclogites mostly exhibits core–rim zoning with increasing grossular (X_gr) and pyrope (X_py) contents, but a few porphyroblastic garnet grains in type I eclogite shows core–mantle zoning with increasing X_py and a slight decrease in X_gr, and mantle–rim zoning with increases in both X_gr and X_py. Garnet rims in type I eclogite have higher X_py than in type II. Petrographic observations and phase equilibria modelling with pseudosections calculated using thermocalc in the NCKMnFMASHO system for three representative samples suggest that the eclogites have experienced four stages of metamorphism: stage I is the pre‐peak temperature prograde heating to the pressure peak (P_max) which was recognized by the garnet core–mantle zoning with increasing X_py and decreasing X_gr. The P–T conditions at P_max constrained from garnet mantle or core compositions with minimum X_gr content are 29–30 kbar at 526–540 °C for type I and 28.2 kbar at 518 °C for type II, suggesting an apparent thermal gradient of ～5.5 °C km^?1. Stage II is the post‐P_max decompression and heating to the temperature peak (T_max), which was modelled from the garnet zoning with increasing X_gr and X_py contents. The P–T conditions at T_max, defined using the garnet rim compositions with maximum X_py content and the Si content in phengite, are 24–27 kbar at 590 °C for type I and 22 kbar at 540 °C for type II. Stage III is the post‐T_max isothermal decompression characterized by the decomposition of lawsonite, which may have resulted in the release of a large amount of fluid bound in the rocks, leading to the formation of epidote, paragonite and glaucophane porphyroblasts. Stage IV is the late retrograde evolution characterized by the overprint of hornblendic amphibole in eclogite and the occurrence of epidote–amphibole facies mineral assemblages in the margins or in the strongly foliated domains of eclogite blocks due to fluid infiltration. The P–T estimates obtained from conventional garnet–clinopyroxene–phengite thermobarometry for the Tianshan eclogites are roughly consistent with the P–T conditions of stage II at T_max, but with large uncertainties in temperature. On the basis of these metamorphic stages or P–T paths, we reinterpreted that the recently reported zircon U–Pb ages for eclogite may date the T_max stage or the later decompression stage, and the widely distributed (rutile‐bearing) quartz veins in the eclogite terrane may have originated from the lawsonite decomposition during the decompression stage rather than from the transition from blueschist to eclogite as previously proposed.     

铀矿层真实厚度的确定和最佳测井点距

本文讨论了最佳测井点距的选择原理,其最佳值大致为8-12.5cm.并从原理上分析了矿层解释厚度增大的主要原因:根据离散测量值所作的分层解释结果必然导致矿层解释厚度的增大.大量的模型测量结果完全证实了理论分析的正确性,并且还提出了合适的解决办法.     

KDX-87型甚低频宽带定向接收与微机分析系统

本文介绍了武汉大学哨声组研制的KDX-87型甚低频宽带定向接收与微机分析系统.该系统适用于测量与分析哨声波传播路径出口、偏振和动态谱.此系统具有以下优点:1.设计制造了小型化天线和便携式接收机,便于携带和架设;合理设计了输入耦合与平衡电路,加上有效的标定方法,使接收系统具有良好的频率响应和通道间性能的一致性.2.实现了数字化宽频带定向分析,有利于减小多路径效应误差,并可获得哨声路径出口与波频率之间的关系.3.利用微机进行哨声动态谱分析,采取了有效的抑制干扰处理,所得谱图分辨率优于普通声图仪制作的谱图.该系统在1988年中日联合哨声定向实验中使用,取得了满意的结果.     

Investigation on the relation between the gravity anomaly，crustal deformation and underground water

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中国东部马鞍山-常熟-启东地带地壳与上地幔结构和速度分布的爆炸地震研究

本文根据马鞍山、常熟两地井中组合爆炸激发的地震波,在马鞍山-常熟-启东长约300余公里的测线上,利用相遇和单支观测系统得到的记录,进行了数据处理、走时拟合和反演计算,并通过射线跟踪和理论地震图等,探讨了地壳介质的横向不均匀性,建立了该区成层地壳结构与速度分布的初步模型。 研究结果表明,该区不同界面的首波和反射波具有不同的特征。根据走时的间断、跳跃,视速度变化,频谱形态与主频率分布,Q值变化与振幅特征表明,在江苏省溧阳地震活动地区,地壳内部存在着深断裂和介质疏松破碎地带。 在该测线所辖地区,地壳由成层介质组成,其平均厚度为32-28km,在该地壳中存在着低速层,向东陆缘地带地壳缓慢变薄。 本文最后讨论了剖面所经溧阳地震地区的深部结构特征。     

印尼苏门答腊8.7级大震对中国陆区的影响

发生在2004年12月26日的印尼苏门答腊8．7级地震，是全球有地震台网以来100多年中记录到的少数几次特大地震之一。初步汇集了在中国陆区观测到的地震活动、地壳形变、地下流体等多学科震时和震后效应的异常变化，包括地震活动性（特别是云南地区）的显著增强；地壳形变观测，尤其是钻孔应变观测记录到地壳应力-应变的震时和震后显著变化，以及地下水温度、化学成分、特别是水位的突出变化。同时，还从库仑破裂应力触发、动态应力触发以及下地壳和上地幔流动变形机制等方面，对这些大震效应作了一些成因机理讨论。     

打滑地层新型孕镶金刚石钻头

在分析打滑地层特点的基础上,指出了钻进该地层所存在的问题,提出了用于打滑地层钻进的新型孕镶金刚石钻头的设计思路,在钻头工作层中采用主、辅两种磨料,并对这两种磨料的工作机理、处理工艺以及该新型钻头的制造进行了阐述.钻头的室内钻进试验结果表明:在钻进极坚硬致密的锆刚玉时,相对于普通金刚石钻头,新型孕镶金刚石钻头的钻进时效提高1.93倍,平均磨损量增加38%,具有高时效、相对寿命长的优点,是打滑地层钻进的理想钻头.     

土壤侵蚀治理范式与生态学理论的耦合关系

目前土壤侵蚀已经成为全球普遍关注的环境问题, 土壤侵蚀治理范式是近年水土保持研 究中的一个热点。本文探讨了“范式”在科学研究中的变迁过程以及对土壤侵蚀防治的重要意义, 并且讨论了土壤侵蚀防治范式与生态学范式之间的耦合关系, 指出生态学思想对土壤侵蚀科学 的发展有重要的借鉴作用, 强调在进行土壤侵蚀研究过程中必须考虑生态因子。土壤侵蚀过程和 生态过程是相互渗透在一起, 它们之间所表现的是相辅相成的耦合关系, 生态学中的自然均衡思 想、系统非平衡态理论、等级缀块动态理论都深刻的影响着土壤侵蚀科学的发展并且都得到不同 程度的应用。在土壤侵蚀研究过程中必须重视生态环境平衡思想。