汶川地震盆地效应的思考与建议

通过实地考察及资料搜集,统计分析了汶川地震中地貌以及局部场地条件对震害的影响。根据受灾城市所在地理位置的不同,将城市分为盆地内部（成都）、盆地边缘（都江堰、绵竹、江油、什邡）、盆地外部（北川）3类,分别统计了震害情况,分析了震害原因。发现在这次地震中盆地效应尤其明显,盆地边缘震害比较严重;盆地中部震害较轻;山区的震害比平原的严重,尤其是在两个距离比较近的山体之间的地区,除了地震灾害之外,滑坡、泥石流等次生灾害也很严重。最后对建筑抗震设计提出了几点建议。     

阜康古牧地活动断裂变形特征研究

对大红沟沟口处河流Ⅰ级和Ⅱ级阶地断裂变形特征研究表明,古牧地断裂活动为古近系泥岩逆冲于第四系之上。断裂破碎带形变主要被两种形式吸收:一是晚第四纪地层拱曲变形作用,二是断裂断错作用。该时期断裂带平均垂直变形速率约为0.26～0.30 mm/a,断裂带内断面发育,既有低角度逆冲断层,也有高角度正断层,组成宽度超过65 m的形变带,破裂带内泥岩揉皱变形明显,最大一次逆冲断错距离为0.4 m,计算震级为M 6.5～6.8。     

吉林东部敦(化)—密(山)断裂带内碱性粗面岩同位素年代学、岩石化学及地质意义

吉林敦化—密山断裂带北段琵河口—黄泥河镇之间新发现有多处的霓辉粗面岩,岩石以普遍富含碱性矿物霓辉石为特点,均呈整合接触覆盖于船底山期碱性玄武岩之上,具高位喷发、低位充填特点,全岩K--Ar年龄测定结果 (25. 64±0. 53 Ma、27. 36±0. 45 Ma、28. 45±0. 56 Ma、28. 55±0. 43Ma、28. 63±0. 45 Ma、28. 65±0. 61 Ma)属渐新世。地球化学数据显示,霓辉粗面岩SiO_2质量分数均值为59. 05%,富碱、高钾,亏损大离子亲石元素(Sr、Ba、V、Cr),富集高场强元素(Nb、Ta、Hf、Zr)和轻稀土元素(LREE),∑REE含量很高,具有右倾型稀土分配型式,显示明显Eu负异常。研究表明,霓辉粗面岩是由碱性玄武质岩浆经强烈分离结晶作用形成的,揭示该区渐新世处于一种强烈的拉张环境,幔源岩浆经历了由碱性玄武岩-碱性粗面岩的演化过程。     

郯庐断裂带南段早白垩世镁铁质岩墙成因及其地质意义

地壳再循环物质交代岩石圈地幔形成不均质的地幔源区,其衍生的镁铁质岩浆岩为揭示地幔演化及壳—幔相互作用提供了重要信息。本文对郯庐断裂带内张八岭隆起南段肥东地区镁铁质岩中的锆石进行LA‑ICP‑MS定年,获得年龄集中在127~122 Ma。镁铁质岩样品中SiO₂含量为51.33%~54.01%,Mg^#值为52.6~70.0,并具有富钠、富碱(σ = 2.46~4.22)的特征,属于亚碱性和高钾钙碱性系列。镁铁质岩样品均富集大离子亲石元素(LILEs,如Ba、Pb、K),相对亏损高场强元素(HFSEs,包括Nb、Ta、Ti等),表现为弧型地球化学特征。锆石Hf‑O同位素研究获得极负的ε_Hf(t)值(-23.4~-21.2)和略高的δ¹⁸O值(5.49‰~6.01‰),与新元古代斜长角闪岩同位素组成显示出一致的演化趋势和相似的分布特征。因此,早白垩世镁铁质岩墙富集的同位素特征主要继承于新元古代(~800 Ma)岩石圈地幔;在郯庐断裂带伸展背景下,由古老岩石圈地幔发生减压熔融形成。

     

胶东栖霞大霞址断裂南段金矿地质特征及成因研究

近年来胶东栖霞大霞址断裂南段发现了多个金矿床。文章从蚀变带特征、矿体空间展布特征等方面阐述了研究区金矿地质特征;从地层、岩浆岩、构造“三位一体”分析总结了控矿因素;通过与典型矿床的分析对比,认为该区金矿床类型属于构造蚀变岩型,金矿与硅化、绢英岩化、黄铁矿化关系最为密切;结合对成矿物质来源、成矿流体运移、沉淀、富集等的认识,对大霞址断裂金矿的成因进行了总结,建立了成矿模式,提出了下一步找矿建议。     

Evolution of the Large-scale Active Manisa Fault,Southwest Turkey: Implications on Fault Development and Regional Tectonics

This paper aims to illustrate and discuss mechanism(s) responsible for the growth and evolution of large-scale corrugated normal faults in southwest Turkey. We report spectacular exposures of normal fault surfaces as parts of the Manisa Fault - a ?50-km-long northeast-ward arched active fault that defines the northwestern edge of the Manisa graben, which is subsidiary to the Gediz Graben. The fault is a single through-going corrugated fault system with distinct along-strike bends. It follows NW direction for 15 km in the south, then bends into an approximately E-W direction in the northwest. The fault trace occurs at the base of topographic scarps and separates the Quaternary limestone scree and alluvium from the highly strained, massive bed-rock carbonates. The fault is exposed on continuous pristine slip surfaces, up to 60 m high. The observed surfaces are polished and ornamented by well-preserved various brittle structural features, such as slip-parallel striations, gutters and tool tracks, and numerous closely spaced extension fractures with straight or crescentic traces. The rocks both in the footwall and hanging-wall of the fault possess a well-developed fault rock stratigraphy made up, from structurally lowest to the top, of massive undeformed recrystallized limestone, a zone of cemented breccia sheets, corrugated polished slip planes, and first brecciated, then unbrecciated scree.

The observed slip surfaces of the Manisa Fault contain two sets of striations that suggest an early phase of sinistral strike-slip and a subsequent normal-slip movements. The first phase is attributed to: (i) approximately E-W-directed compression that commenced during either (?) Early-Middle Pliocene time or (ii) the current extensional tectonics and consequent modern graben formation in southwest Turkey that initiated during the Plio-Quaternary. During this period, the Manisa Fault was reactivated and it became a major segment. Stress inversion of fault slip data suggests that southwest Turkey has been experiencing multidirectional crustal extension, with components of approximately N-S, E-W, NE-SW and NW-SE extension. Following the reactivation, the inherited fault segments were connected to each other through interaction, linkage and amalgamation of previously discontinuous and overlapping smaller stepping adjacent faults. Linkage was via the formation of new connecting (breaching) fault(s) or by curved propagation of fault-tips. The result is a single through-going corrugated fault trace with distinct along-strike bends. The final geometry of the Manisa Fault is thus the combined result of reactivation and continuing interaction between previously discontinuous segmented fault traces.     

苏北盆地高邮凹陷隐蔽性断层构造特征分析与预测

晚白垩世晚期—新生代发育的高邮凹陷,是苏北盆地南部典型富含油气的半地堑式断陷盆地,自南向北分为南断阶、深凹带与北斜坡。该凹陷复杂断裂构造系统与相应的沉积格局受印支期NEE向逆冲基底断层系与晚侏罗世伊泽纳崎板块高速斜向俯冲形成的NNE向左行平移基底断层系影响,同时受古近纪期间区域近SN向拉张应力状态控制。北斜坡东部花瓦构造带主体EW向正断层与NNE向隐蔽性断层发育了限制型、连接型、复合型3类隐蔽性断块圈闭模式,同时在平面上形成多种组合样式。通过研究花瓦区隐蔽性断块圈闭实例与有限差分法数值模拟,分析总结出高邮凹陷NNE向隐蔽性断层的成因机制与构造特征,并推断了5条隐蔽性断层发育带。     

我国西南地区斑岩矿床区域成矿环境

本文对我国西南地区斑岩Cu(-Mo-Au)矿床形成的区域成矿环境进行了总结研究。我国西南地区斑岩矿床,构造上位于全球特提斯斑岩成矿带东段,与青藏高原演化密切相关,形成于青藏高原演化不同阶段。我国西南地区斑岩矿床形成时代为晚三叠世、早白垩世、古近纪和中新世等4个时期。斑岩矿床形成的区域成矿环境具有多样性,包括俯冲造山岛弧、同碰撞、后碰撞和大陆转换板块边界等四类构造环境。根据斑岩矿床成岩成矿时代和成矿环境,我国西南地区斑岩矿床可划分为义敦-中甸印支期斑岩成矿带、玉龙-马拉松多古近纪斑岩成矿带、丽江-金平古近纪斑岩成矿带、冈底斯古近纪-新近纪斑岩成矿带和班公湖-怒江燕山期斑岩成矿带等五个成矿带。与世界上多数斑岩矿床一样,我国西南地区斑岩矿床与区域深大走滑断裂存在着明显的空间分布关系。     

河南下汤温泉与车村—鲁山断裂的关系及电测深法在其勘查中的应用

通过对车村—鲁山大断裂与河南鲁山五大温泉关系的探讨,并应用激电测深法勘探、RGIS软件反演解释技术,查明下汤温泉东西两侧1 500 m范围内水文地质条件,认为下汤温泉即受控于近东西向车村—鲁山断裂(F1),也受控于北东向F4断裂。前者为一级控热导热构造,是深部热源向上对流的主要通道;后者为二级控热导热构造。在地形和水头压差的驱动下,地下水沿着断裂带自西向东缓慢的运移,期间受地壳内部热源传导,在排泄区受到北东向F4断裂的控制,向地表运移,出露成泉。