Static and Dynamic Moduli of the Seismogenic Layer in Italy

Summary Static and dynamic elastic moduli of Calcare Massiccio (mudstone-limestone) have been measured as a function of frequency over nine decades, using three different standard methods: uniaxial static compression, dual cantilever forced oscillations, and measurement of ultrasonic velocities. An accurate critical comparison using the same techniques on a poly-methyl-methacrylate (PMMA) material shows that an unresolvable 10 to 20% bias exists in the two low frequency standard techniques, whereas the ultrasonic measurements are more accurate and reproducible within 5%. No significant frequency dependence is found for Calcare Massiccio, which gives a Youngs modulus of (75±7) GPa and a Poisson#x2019;s ratio of (0.28#x2009;#x00B1;#x2009;0.02).     

袖阀管注浆技术在灰岩地层中的应用

为保证灰岩地基处理中充填物能够与周围环境固结成为一个整体，且具有一定的强度，本次地基处理工程采用了袖阀管注浆和双液注浆相结合的方法，使其充填物在灰岩地基中形成树枝状、叶面状等的水泥结块，从而提高桩端下卧持力层稳定性及处理体的承载力。     

库鲁克塔格地区巷古勒塔格组瘤状灰岩及其沉积环境

新疆库鲁克塔格地区巷古勒塔格组发育瘤状灰岩,是一种深水沉积序列.本区瘤状灰岩形成于台缘斜坡带,滑塌重力流改造原岩形态,并分为富泥型、过渡型及富灰型3种类型.富泥型瘤状灰岩沉积在CCD线之下,受深度海水溶解作用改造.过渡型瘤状灰岩形成在CCD附近,受海底底流和深度海水溶解的双重作用改造.富灰型瘤状灰岩形成在CCD之上,受周期性的重力流作用的改造和海底底流的溶解作用.岩性组合表明,早奥陶世库鲁克塔格地区处于迅速海侵阶段.     

Limestone assimilation and the origin of CO2 emissions at the Alban Hills (Central Italy): Constraints from experimental petrology

The Alban Hills volcanic region (20 km south of Rome, in the Roman Province) emitted a large volume of potassic magmas (> 280 km³) during the Quaternary. Chemical interactions between ascending magmas and the ∼ 7000–8000-m-thick sedimentary carbonate basement are documented by abundant high temperature skarn xenoliths in the eruptive products and have been frequently corroborated by geochemical surveys. In this paper we characterize the effect of carbonate assimilation on phase relationships at 200 MPa and 1150–1050 °C by experimental petrology. Calcite and dolomite addition promotes the crystallization of Ca-rich pyroxene and Mg-rich olivine respectively, and addition of both carbonates results in the desilication of the melt. Furthermore, carbonate assimilation liberates a large quantity of CO₂-rich fluid. A comparison of experimental versus natural mineral, glass and bulk rock compositions suggests large variations in the degree of carbonate assimilation for the different Alban Hills eruptions. A maximum of 15 wt.% assimilation is suggested by some melt inclusion and clinopyroxene compositions; however, most of the natural data indicate assimilation of between 3 and 12 wt.% carbonate. Current high CO₂ emissions in this area most likely indicate that such an assimilation process still occurs at depth. We calculate that a magma intruding into the carbonate basement with a rate of ∼ 1 – 2 · 10⁶ m³/year, estimated by geophysical studies, and assimilating 3–12 wt.% of host rocks would release an amount of CO₂ matching the current yearly emissions at the Alban Hills. Our results strongly suggest that current CO₂ emissions in this region are the shallow manifestation of hot mafic magma intrusion in the carbonate-hosted reservoir at 5–6 km depth, with important consequences for the present-day volcanic hazard evaluation in this densely populated and historical area.     

四川桂花灰岩地区低信噪比高陡构造成像处理方法

四川桂花三维地震资料采集属页岩气低密度三维地震,针对炮道密度低、覆盖次数低、二叠和三叠纪灰岩激发占比较大等特点,采用层析静校正、弱信号保护等处理技术,有效解决了研究区低信噪比问题;利用叠前数据五维数据重构处理方法,有效解决了受大型障碍物影响而导致的面元及偏移距分配不均等问题,提高了信噪比,为叠前深度成像处理奠定了基础。针对灰岩低噪比和高陡构造的准确成像问题,采用基于构造约束的网格层析速度建模结合叠前深度偏移成像方法,保证了成像效果。     

The Buday’ah Formation, Sultanate of Oman: A Middle Permian to Early Triassic oceanic record of the Neotethys and the late Induan microsphere bloom

The Middle Permian to Lower Triassic Buday’ah section, exposed in the Oman Mountains, is the first deep-sea section to be described in the Neotethys. The oceanic sediments were deposited along the southern Tethys margin in the newly formed Hawasina Basin. It is one of the few places where true Tethyan Permian radiolarites are exposed that allow the documentation of CCD evolution through time. The succession begins as oceanic crust pillow basalt with red ammonoid-rich pelagic limestone occurring both above and within inter-pillow cavities; the new occurrence of Clarkina postbitteri hongshuiensis indicates a late Capitanian age for the carbonate. The sharp change to overlying late Capitanian to Changhsingian radiolarite reflects rapid subsidence about 10 Myrs after initial continental breakup that resulted in the formation of the Neotethys Ocean. New conodonts indicate that the Permian-Triassic boundary succession occurs in the first platy lime mudstone beds above a Changhsingian siliceous to calcareous shale unit. The platy lime mudstone beds include an Upper Griesbachian bloom of calcite filled spheres (radiolarians?) that marks a potential world-wide event. New conodonts indicate an early Olenekian age for overlying grey papery limestone that are devoid of both macrofossils and trace fossils indicating that recovery from the Late Permian extinction has not yet progressed within this deep-water environment.δ¹³C_org, isotope values have not been disturbed and they show a negative shift just below the Permian-Triassic transition and a second one at the parvus zone level above. The Buday’ah succession may represent the most distal and probably deepest Permian and Lower Triassic depositional sequence within the basin.     

四川盆地中部侏罗系大安寨段含有机质泥质介壳灰岩储层的认识及其意义

四川盆地中部下侏罗统大安寨段可划分为三个亚段,主要由暗色泥页岩、结晶介壳灰岩、泥质介壳灰岩三种岩性构成。暗色泥页岩形成于深湖—半深湖相环境,是主要的烃源岩,滨浅湖高能滩相结晶介壳灰岩一向被认为是主要储层,其储集空间以裂缝为主。露头地质调查、岩心和薄片观察、物性资料及试油资料的分析表明,浅湖—半深湖较低能滩相含有机质泥质介壳灰岩是主要的储集层和产层,单层厚度薄,但累积厚度较大,分布面积广,常夹于暗色泥页岩中,源储一体,更有利于成藏。这类泥质介壳灰岩的壳间孔构成了主要的储集空间,壳间孔平行于壳体的长轴方向排列,并常见黑色有机质充填。认为四川盆地大安寨段的油气勘探方向可由结晶介壳灰岩向含有机质的泥质介壳灰岩拓展,浅湖—半深湖较低能滩沉积相带可成为新的勘探领域。初步预测大安寨段上部的一亚段新增有利勘探面积6 100 km2,中部的一三亚段新增有利勘探面积6 600 km2。     

淮北矿区五沟煤矿太原组上段灰岩岩溶裂隙水富水性及径流特征

五沟煤矿太原组上段灰岩岩溶裂隙水是矿井主采煤层（10煤）的主要充水含水层。通过对矿区水文地质边界条件、地面抽水试验和井下放水试验的分析,认为矿区水文地质边界受制于周边的较大型隔阻水断层,从而形成了较封闭的地下水系统;太原组上段灰岩含水层的富水性在平面上具有不均一性,在垂向具有随着深度的增加,岩溶发育有减弱的趋势,基本上属弱富水含水层,仅在局部构造发育带为中等富水含水层。利用利用surfer软件,绘制出矿区太原组灰岩水位等值线图;从图上可以看出,矿区目前太原组含水层水位标高总体呈北高南低,中间高两边低的态势,并在井田西南部形成以水5孔及J5-1孔为中心的低水位区。该研究对目前矿井防治水工作具有重要的指导意义。     

鱼台凹陷边部玄武岩覆盖区地热勘探方法及应用效果

研究区位于鱼台凹陷边部,上覆较厚的沉积地层,为地热形成提供了良好的盖层,热储层为奥陶纪马家沟群,其顶板埋深均超1000m,最大埋深可达3000m。理论上在该地区开展地震勘探寻找目标体是一种效果较佳的物探方法,但地表下约300~600m隐伏新生代玄武岩,其对地震波具有强屏蔽作用,造成玄武岩下伏地层的地震反射信息很弱,甚至无地震反射信息,严重影响玄武岩下伏地层的成像效果;CSAMT法在该低阻沉积地层覆盖区电磁信号同样存在低阻屏蔽,衰减很快,近场效应明显,勘探深度不超过1000m。本文以区域重力场对嘉祥断裂初步推断为基础,大地电磁测深（MT）为主,常规电测深为佐证的物探手段,能够较好地降低玄武岩及低阻屏蔽的影响,提高深部勘探能力,划分地热盖层与热储层的分界线,圈定导热导水构造,最终获得鲁西南地区温度最高的灰岩热储地热井。