长江中下游庐江-枞阳火山岩矿集区深部结构与成矿作用   总被引：32，自引：16，他引：16  

董树文  项怀顺  高锐  吕庆田  李建设  战双庆  卢占武  马立成 《岩石学报》2010,26(9):2529-2542

为探测长江中下游成矿带庐江-枞阳白垩纪火山岩盆地和铁、硫矿集区深部构造和地壳结构,探讨成矿深部控制条件,作者完成了穿越火山岩盆地的深反射地震剖面(150km,记录30s)和罗河铁矿区浅层高分辨反射地震剖面(20km),以及平行剖面的大地电磁、高精度重磁剖面,揭示了矿集区全地壳精细结构和电磁结构,同时开展区域构造测量和火山岩年代学研究,获得了新的认识。证实"耳状"的庐-枞火山岩盆地是一个沿北东向罗河断裂向东侧发育的非对称火山盆地,排除了另一半被断在西侧红层之下的判断;罗河断裂是一条切穿MOHO的深断裂,倾向南东,是引导地幔流体和岩浆上涌和喷发的通道,在中地壳形成岩浆房(反射亮斑);鉴别出多层界面,火山岩-侏罗系厚度约4～5km(其中火山岩厚度约3km),三叠系-震旦系变形层底界深度大致18～20km,变质基底组成中下地壳,MOHO平缓向北西倾,深度33～31km;追踪郯-庐断裂带的深部产状,陡立延伸到MOHO,宽约10km。从而揭示了早白垩系(132～127Ma)庐-枞火山岩矿集区深部过程与成矿、控矿作用。  相似文献   

莒县国土资源局信访工作探析     

井富磊  卢守润  王龙增 《山东地质》2010,(2):52-53

莒县国土资源局干部职工通过走进基层、走进群众中间,摸排国土资源信访矛盾,查找信访苗头线索,及时制定应对方案,筑牢接访三道防线,努力将矛盾化解在萌芽状态,信访工作取得明显成效。  相似文献   

The evolution of rifting on the volcanic margin of the Pelotas Basin and the contextualization of the Paraná–Etendeka LIP in the separation of Gondwana in the South Atlantic     

《Marine and Petroleum Geology》2014

The Pelotas Basin is the classical example of a volcanic passive margin displaying large wedges of seaward-dipping reflectors (SDR). The SDR fill entirely its rifts throughout the basin, characterizing the abundant syn-rift magmatism (133–113 Ma). The Paraná–Etendeka Large Igneous Province (LIP), adjacent to west, constituted the pre-rift magmatism (134–132 Ma). The interpretation of ultra-deep seismic lines showed a very different geology from the adjacent Santos, Campos and Espírito Santo Basins, which constitute examples of magma-poor passive margins. Besides displaying rifts totally filled by volcanic rocks, diverse continental crustal domains were defined in the Pelotas Basin, such as an outer domain, probably constituted by highly stretched and permeated continental igneous crust, and a highly reflective lower crust probably reflecting underplating.The analysis of rifting in this portion of the South Atlantic is based on seismic interpretation and on the distribution of regional linear magnetic anomalies. The lateral accretion of SDR to the east towards the future site of the breakup and the temporal relationship between their rift and sag geometries allows the reconstitution of the evolution of rifting in the basin. Breakup propagated from south to north in three stages (130–127.5; 127.5–125; 125–113 Ma) physically separated by oceanic fracture zones (FZ). The width of the stretched, thinned and heavily intruded continental crust also showed a three-stage increase in the same direction and at the same FZ. Consequently, the Continental-Oceanic Boundary (COB) shows three marked shifts, from west to east, from south to north, resulting into rift to margin segmentation. Rifting also propagated from west to east, in the direction of the final breakup, in each of the three segments defined. The importance of the Paraná–Etendeka LIP upon the overall history of rupturing and breakup of Western Gondwanaland seems to have been restricted in time and in space only to the Pelotas Basin.  相似文献   

Age and impacts of the caldera-forming Aniakchak II eruption in western Alaska     

J.J. Blackford  R.J. Payne  M.P. Heggen  A. de la Riva Caballero  J. van der Plicht 《Quaternary Research》2014

The mid-Holocene eruption of Aniakchak volcano (Aniakchak II) in southwest Alaska was among the largest eruptions globally in the last 10,000 years (VEI-6). Despite evidence for possible impacts on global climate, the precise age of the eruption is not well-constrained and little is known about regional environmental impacts. A closely spaced sequence of radiocarbon dates at a peatland site over 1000 km from the volcano show that peat accumulation was greatly reduced with a hiatus of approximately 90–120 yr following tephra deposition. During this inferred hiatus no paleoenvironmental data are available but once vegetation returned the flora changed from a Cyperaceae-dominated assemblage to a Poaceae-dominated vegetation cover, suggesting a drier and/or more nutrient-rich ecosystem. Oribatid mites are extremely abundant in the peat at the depth of the ash, and show a longer-term, increasingly wet peat surface across the tephra layer. The radiocarbon sample immediately below the tephra gave a date of 1636–1446 cal yr BC suggesting that the eruption might be younger than previously thought. Our findings suggest that the eruption may have led to a widespread reduction in peatland carbon sequestration and that the impacts on ecosystem functioning were profound and long-lasting.  相似文献   

卫星热红外遥感技术在火山区地热探测中的应用——以内蒙古锡林郭勒火山区为例   总被引：1，自引：0，他引：1       下载免费PDF全文

彭芬  黄少鹏  时庆金  程玉祥  荆勇河 《地质科学》2014,(3):899-914

能源的全球性短缺以及全球环境问题的日益加剧,使得绿色新能源的研究与开发成为当今世界许多国家的一项重要任务。地热资源作为其中一员其重要性日益凸显。在地热资源的勘查中,传统的地质和地球物理勘探投入高、难度大,而遥感技术具有经济、高效、覆盖范围广等优势,已逐渐成为地热资源探测与调查的一种新技术手段。地热能开发的首选地区往往是新生代火山活动区,因其在相对较小的深度内就能获得很高的温度。本文综述了国内外利用遥感技术探测火山地热的发展历史和研究现状,介绍了这项技术在美国黄石公园、日本阿苏火山以及我国长白山火山和腾冲火山的应用。同时选取内蒙古锡林郭勒盟新生代火山活动构造区作为实例,利用美国NASA陆地卫星Landsat-7 ETM+第6波段的红外遥感数据反演了研究区的地表温度,结合ETM+7-4-1波段组合影像的地质构造解译结果以及其它相关资料对研究区地表温度分布进行了分析。结果表明,区内红外遥感地表温度异常区多位于北东东与北西向构造的交汇处或与环形构造密切相关。本文圈定了7个地表温度异常区作为这一地区下一步地热资源勘查的远景区。  相似文献   

阿尔泰南缘麦兹盆地萨吾斯铅锌矿床控矿铁闪石矽卡岩的⁴⁰Ar/³⁹Ar年代学研究     

刘伟  刘丽娟  刘秀金 《岩石学报》2014,30(6):1535-1544

萨吾斯矿床位于麦兹盆地东部,是一个新近发现和勘探的铅锌矿床。萨吾斯铅锌矿床赋存于下泥盆统康布铁堡组上亚组凝灰岩、流纹岩及其沉积碳酸盐夹层,矿（化）体直接受石榴黑云矽卡岩和铁闪石矽卡岩控制,表现出火山喷流-沉积成矿和矽卡岩矿床的双重特征。这两类矿床的重要区别之一是同生和后生成矿。对主要矽卡岩矿物铁闪石进行精确的Ar-Ar年龄测定,将其与康布铁堡组流纹岩的年龄对比,有助于确定萨吾斯铅锌矿床的成因。高精度、高灵敏度激光⁴⁰Ar-³⁹Ar测年方法,为解决闪石类低K矿物的定年提供了新的手段。岩芯样品SW85中,铁闪石晶粒较大、晶形发育,与闪锌矿、碳酸盐矿物和石榴子石都具有平直的边界,而不是复杂交生,不含矿物和流体包裹体,代表了相对简单均一的系统。对SW85的铁闪石做了激光⁴⁰Ar-³⁹Ar测年,其结果为412±15Ma,与康布铁堡组流纹岩的SIMS锆石U-Pb年龄（401±2.7Ma）和别斯萨拉玢岩的SIMS锆石U-Pb年龄（401±3.1Ma）在误差范围内一致,表明矽卡岩和铅锌矿的形成与康布铁堡组流纹质火山岩的喷发及其碎屑岩的沉积是同时的,成因上密切相关。其次,矽卡岩呈层状产出,局限于康布铁堡组凝灰岩及其铁锰钙质碳酸盐夹层的范围内;石榴子石为铁铝榴石、锰铝榴石,闪石为铁闪石,缺失透辉石、钙铁辉石。上述特征与接触交代矽卡岩不同,后者以钙铝榴石、钙铁榴石、透辉石/钙铁辉石为特征,闪石为角闪石。接触交代矽卡岩矿床是后成矿床,它晚于岩浆侵入体的围岩。综上所述,萨吾斯铅锌矿是一个与康布铁堡组火山喷发和浅成侵入有关的喷流-沉积矿床。麦兹盆地的控盆断裂巴寨断裂从北西端向南东发展而成。阿巴宫-库尔提断裂和琼库尔断裂是克兰盆地的控盆断裂,它们在北西撒开、向南东收敛,具有羽状张剪性断裂的特征。因此,阿尔泰南缘在早泥盆世具有活动陆缘的局部拉张性质。西伯利亚板块与哈萨克斯坦-准噶尔板块的推错,在阿尔泰南缘产生局部张剪性应力场,从而形成了上述断裂以及早泥盆世火山-沉积盆地。  相似文献   

中国东北地区中生代构造体制的转变:来自火山岩时空分布与岩石组合的制约   总被引：13，自引：3，他引：10  

孟凡超  刘嘉麒  崔岩  高金亮  刘祥  童英 《岩石学报》2014,30(12):3569-3586

东北地区中生代经历了蒙古-鄂霍茨克构造体系向太平洋构造体系的转换,形成了不同期次火山活动。本文归纳总结了露头区与覆盖区中生代火山岩的年代学、空间分布、岩石组合以及地球化学特征,揭示了两个构造域的时空分布范围。该区火山岩锆石U-Pb年龄统计结果表明中生代存在五期火山活动:早-中侏罗世(190~160Ma)、晚侏罗世(160~145Ma)、早白垩世早期(145~120Ma)、早白垩世晚期(120~100Ma)、晚白垩世早期(100~90Ma)。早-中侏罗世火山岩分布较少,火山岩仅分布在大兴安岭西部满洲里地区和东部张广才岭以及南侧辽宁北票-朝阳地区,火山岩属于高钾钙碱性系列,为蒙古-鄂霍茨克海闭合和法拉隆板块双俯冲作用的产物。晚侏罗世东北地区火山活动明显增强,主要分布在大兴安岭地区,张广才岭以及小兴安岭也有少量分布。西部大兴安岭地区以粗面安山岩、粗面岩为主,属于同碰撞造山成因,为蒙古-鄂霍茨克海闭合造山环境产物。东部以中酸性、酸性岩为主,为法拉隆板块背离欧亚大陆,岩石圈伸展引起的壳源物质熔融产物。早白垩世早期火山活动最为强烈,火山岩主要分布在大兴安岭地区。岩性以高钾钙碱性系列的粗面玄武安山岩、粗面安山岩、安山岩、粗面岩为主,为蒙古-鄂霍茨克海闭合造山后伸展环境产物。早白垩世晚期火山岩主要分布在松辽盆地内部。火山岩以中酸性岩为主,属于中钾-高钾钙碱性系列,为伊泽奈崎板块俯冲引起的弧后拉张,软流圈上涌导致年轻地壳熔融的产物。晚白垩世早期火山岩仅分布在小兴安岭及吉林、黑龙江省东部地区。火山岩为一套玄武岩、玄武安山岩、安山岩和英安岩组合,属于中钾钙碱性系列,是伊泽奈崎-库拉板块高角度俯冲的大陆边缘岩浆活动产物。东北地区中生代不同期次火山岩记录了蒙古-鄂霍茨克构造域向太平洋构造域转换过程及其时空影响范围。  相似文献   

火山喷发形式与挥发分含量   总被引：1，自引：0，他引：1  

贾祖冰  夏群科  田真真 《岩石学报》2014,30(12):3701-3708

火山喷发是由地球深部物质发生部分熔融产生的岩浆上涌至地表所形成的一种地质现象,是地球内部能量释放的主要途径之一。有些火山喷发极为猛烈,产生的大量火山灰能够在长达几个月的时间内影响当地气候环境,甚至可以在一瞬间掩埋整座城市;而有些火山喷发时只有大量的熔岩从火山口中静静地溢出,人们甚至可以在不远处进行观赏。火山喷发具有何种程度的破坏力取决于其喷发形式,而挥发分含量是影响喷发形式的重要因素之一。本文简述了几种常见的喷发形式及其相互之间可能存在的转化关系,着重论述了挥发分含量在其中所起到的作用,同时介绍了几种可能的去气模型及常见的测量岩浆挥发分含量的方法。其中使用单斜辉石斑晶来反演大陆玄武岩原始岩浆水含量的方法预计会在未来的研究中得到普及。  相似文献   

Under the surface: Pressure-induced planetary-scale waves,volcanic lightning,and gaseous clouds caused by the submarine eruption of Hunga Tonga-Hunga Ha'apai volcano     

David A. Yuen  Melissa A. Scruggs  Frank J. Spera  Yingcai Zheng  Hao Hu  Stephen R. McNutt  Glenn Thompson  Kyle Mandli  Barry R. Keller  Songqiao Shawn Wei  Zhigang Peng  Zili Zhou  Francesco Mulargia  Yuichiro Tanioka 《地震研究进展（英文）》2022,2(3):100134

We present a narrative of the eruptive events culminating in the cataclysmic January 15, 2022 eruption of Hunga Tonga-Hunga Ha'apai Volcano by synthesizing diverse preliminary seismic, volcanological, sound wave, and lightning data available within the first few weeks after the eruption occurred. The first hour of eruptive activity produced fast-propagating tsunami waves, long-period seismic waves, loud audible sound waves, infrasonic waves, exceptionally intense volcanic lightning and an unsteady volcanic plume that transiently reached—at 58 ?km—the Earth's mesosphere. Energetic seismic signals were recorded worldwide and the globally stacked seismogram showed episodic seismic events within the most intense periods of phreatoplinian activity, and they correlated well with the infrasound pressure waveform recorded in Fiji. Gravity wave signals were strong enough to be observed over the entire planet in just the first few hours, with some circling the Earth multiple times subsequently. These large-amplitude, long-wavelength atmospheric disturbances come from the Earth's atmosphere being forced by the magmatic mixture of tephra, melt and gasses emitted by the unsteady but quasi-continuous eruption from 0402±1–1800 UTC on January 15, 2022. Atmospheric forcing lasted much longer than rupturing from large earthquakes recorded on modern instruments, producing a type of shock wave that originated from the interaction between compressed air and ambient (wavy) sea surface. This scenario differs from conventional ideas of earthquake slip, landslides, or caldera collapse-generated tsunami waves because of the enormous (～1000x) volumetric change due to the supercritical nature of volatiles associated with the hot, volatile-rich phreatoplinian plume. The time series of plume altitude can be translated to volumetric discharge and mass flow rate. For an eruption duration of ～12 ?h, the eruptive volume and mass are estimated at 1.9 ?km³ and ～2 900 ?Tg, respectively, corresponding to a VEI of 5–6 for this event. The high frequency and intensity of lightning was enhanced by the production of fine ash due to magma—seawater interaction with concomitant high charge per unit mass and the high pre-eruptive concentration of dissolved volatiles. Analysis of lightning flash frequencies provides a rapid metric for plume activity and eruption magnitude. Many aspects of this eruption await further investigation by multidisciplinary teams. It represents a unique opportunity for fundamental research regarding the complex, non-linear behavior of high energetic volcanic eruptions and attendant phenomena, with critical implications for hazard mitigation, volcano forecasting, and first-response efforts in future disasters.  相似文献   

桂西南那坡盆地河口组沉凝灰岩的时代与来源及其大地构造意义SCIEI北大核心CSCD     

夏磊  闫全人  向忠金  郑洪波  牛睿 《岩石学报》2022,38(3):883-900

桂西南那坡盆地位于八布-Song Hien构造带,发育早-中三叠世岩浆岩和巨厚海相碎屑岩系,是研究华南地块南缘古特提斯造山过程的关键地区。本文对那坡盆地中三叠统河口组中-上部的两套沉凝灰岩开展了详细的岩石学、地球化学和锆石U-Pb-Hf同位素分析研究。两件沉凝灰岩样品LA-ICP-MS锆石U-Pb定年结果分别为240.6±1.0Ma和236.3±0.8Ma,指示河口组碎屑岩沉积时代为中三叠世拉丁期,部分为晚三叠世卡尼期早期。全岩地球化学结果显示,该沉凝灰岩属于亚碱性英安质,富集轻稀土(LREEs)和大离子亲石元素(LILEs)、Rb、Th和U,亏损高场强元素(HFSEs),具有显著的Nb、Ta和Ti负异常。沉凝灰岩锆石具有较低的ε_(Hf)(t)值(-18.6~-6.3)和较老的地壳模式年龄(t_(DM)^(C)=1664~2434Ma),结合锆石微量元素特征认为其形成于俯冲环境。整体上,那坡盆地河口组沉凝灰岩表现出俯冲作用形成的岛弧火山岩地球化学特征,推断其来源于桂西南凭祥地区的中-晚三叠世酸性火山岩。结合已有区域地质调查成果,认为华南地块南缘八布-Cao Bang古特提斯分支洋盆于晚二叠世至晚三叠世早期向北俯冲,随后自西向东呈“剪刀”式逐渐闭合。华南地块与北越地块完全碰撞拼合的时间发生在晚三叠世中晚期。  相似文献