斑岩型和浅成低温热液型矿床成矿流体与找矿预测研究:以华南若干典型矿床为例     

倪培  迟哲  潘君屹 《地学前缘》2020,27(2):60-78

斑岩型和浅成低温热液型矿床是全球铜、钼、金、银的主要来源之一,具有重要经济价值。这两类矿床之间通常存在紧密的时空关系,对其成矿流体性质和演化的解剖不仅有利于探究金属沉淀机制,也有助于揭示两者之间的内在成因联系。本文在综述国内外重要研究前沿基础上,以中国华南富家坞斑岩型铜钼(金)矿、桐村斑岩钼矿,以及邱村和安村浅成低温热液金矿为例,系统总结了斑岩型和浅成低温热液型矿床流体特征、演化规律和金属沉淀机制、探讨了从斑岩型到浅成低温热液型流体演化的“气相迁移”模型,并以福建紫金山铜金矿床为例,介绍了应用流体填图进行找矿预测的实例。  相似文献   

Impact of evaporation on field capacity during water drainage redistribution in a soil     

Ali Aldrees  Amine Hafsi 《水文研究》2021,35(2):e14028

To this day, field capacity (FC) is rarely defined in the context of soil properties, and the use of non-physical simplistic models is the common way to normalize water content at FC. In this study, the problem of water drainage redistribution in a soil column with and without the presence of evaporation (EV) was extensively studied. Analytical solutions for the Richards equation were established for the case of water drainage redistribution through a deeply wetted soil water column with and without EV at FC conditions. Water retention and depth evolution curves were plotted first, using different EV values of (2 $\frac{\mathbf{mm}}{\mathbf{day}}$, 5 $\frac{\mathbf{mm}}{\mathbf{day}}$ and 8 $\frac{\mathbf{mm}}{\mathbf{day}}$) and second, for different drainage redistribution durations of (1 day, 4 days and 6 days) where EV was set to zero for the case with no EV or to a fixed value of 5 $\frac{\mathbf{mm}}{\mathbf{day}}$ for the case with EV. The results suggest that EV plays a significant role in soil water drainage suggesting that, in the presence of EV, the FC drying front reaches much higher depths in the soil water profile than if EV is turned off. It was also concluded that FC reaches deeper depths faster the stronger EV is acting at the surface of a soil water column. Additionally, the results suggest that the texture of the soil receiving drainage controls the amount of water available for EV and as a result, EV was found to play a stronger role the smaller the hydraulic conductivity of the soil is.  相似文献   

Winkler model for dynamic response of composite caisson–piles foundations: Seismic response     

《Soil Dynamics and Earthquake Engineering》2014

A simplified method with a dynamic Winkler model to study the seismic response of composite caisson–piles foundations (CCPF¹) is developed. Firstly, with the dynamic Winkler model, the kinematic response of the CCPF subjected to vertically propagating seismic S-wave is analyzed by coupling the responses of caisson part and pile part. Secondly, a simplified model for the foundation–structure system is created with the structure simplified as a lumped mass connected to the foundation with an elastic column, and through the Fast Fourier Transformation (FFT) this model is enabled to solve transient seismic problems. Thirdly, the proposed method for the seismic response of CCPF-structure systems is verified by comparison against 3D dynamic finite element simulation, in which the Domain Reduction Method (DRM²) is utilized. Lastly, the mechanism and significance of adding piles in improving the earthquake resistance of the foundation and structure is analyzed through an example with different soil conditions. Discovered in this study is that adding piles under the caisson is an efficient way to increase seismic resistant capability of the soil–foundation–structure system, and the main mechanism of that is the elimination of the pseudo-resonance.  相似文献   

Sunspot numbers based on historic records in the 1610s: Early telescopic observations by Simon Marius and others     

R. Neuhuser  D. L. Neuhuser 《Astronomische Nachrichten》2016,337(6):581-620

Hoyt & Schatten (1998) claim that Simon Marius would have observed the sun from 1617 Jun 7 to 1618 Dec 31 (Gregorian calendar) all days, except three short gaps in 1618, but would never have detected a sunspot – based on a quotation from Marius in Wolf (1857), but mis‐interpreted by Hoyt & Schatten. Marius himself specified in early 1619 that for one and a half year... rather few or more often no spots could be detected... which was never observed before (Marius 1619). The generic statement by Marius can be interpreted such that the active day fraction was below 0.5 (but not zero) from fall 1617 to spring 1619 and that it was 1 before fall 1617 (since August 1611). Hoyt & Schatten cite Zinner (1952), who referred to Zinner (1942), where observing dates by Marius since 1611 are given but which were not used by Hoyt & Schatten. We present all relevant texts from Marius where he clearly stated that he observed many spots in different form on and since 1611 Aug 3 (Julian) = Aug 13 (Greg.) (on the first day together with Ahasverus Schmidnerus); 14 spots on 1612 May 30 (Julian) = Jun 9 (Greg.), which is consistent with drawings by Galilei and Jungius for that day, the latter is shown here for the first time; at least one spot on 1611 Oct 3 and/or 11 (Julian), i.e. Oct 13 and/or 21 (Greg.), when he changed his sunspot observing technique; he also mentioned that he has drawn sunspots for 1611 Nov 17 (Julian) = Nov 27 (Greg.); in addition to those clearly datable detections, there is evidence in the texts for regular observations. For all the information that can be compared to other observers, the data from Marius could be confirmed, so that his texts are highly credible. We also correct several shortcomings or apparent errors in the database by Hoyt & Schatten (1998) regarding 1612 (Harriot), 1615 (Saxonius, Tard´e), 1616 (Tard´e), 1617–1619 (Marius, Riccioli/Argoli), and Malapert (for 1618, 1620, and 1621). Furthermore, Schmidnerus, Cysat, David & Johann Fabricius, Tanner, Perovius, Argoli, and Wely are not mentioned as observers for 1611, 1612, 1618, 1620, and 1621 in Hoyt & Schatten. Marius and Schmidnerus are among the earliest datable telescopic sunspot observers (1611 Aug 3, Julian), namely after Harriot, the two Fabricius (father and son), Scheiner, and Cysat. Sunspots records by Malapert from 1618 to 1621 show that the last low‐latitude spot was seen in Dec 1620, while the first high‐latitude spots were noticed in June and Oct 1620, so that the Schwabe cycle turnover (minimum) took place around that time, which is also consistent with the sunspot trend mentioned by Marius and with naked‐eye spots and likely true aurorae. We consider discrepancies in the Hoyt & Schatten (1998) systematics, we compile the active day fractions for the 1610s, and we critically discuss very recent publications on Marius which include the following Maunder Minimum. Our work should be seen as a call to go back to the historical sources. (© 2016 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)  相似文献   

太行山中段城南庄一带隐伏岩体及找矿前景分析     

吴云霞 《地质与勘探》2021,57(2):315-324

麻棚和赤瓦屋岩体都位于太行山中段热液金属矿成矿区内,在其周围已发现石湖石英脉大型金矿等60余处热液型矿床(点),其深部和外围可能存在找矿前景。本文通过探讨太行山中段城南庄一带遥感环形构造和重力负场特征与金属矿床和岩体的耦合关系,从城南庄卫星式-多层蘑菇群式遥感环形构造群、重力负场、中酸性岩脉侵入和温泉五种证据,推测城南庄深部存在比麻棚和赤瓦屋岩体大近六倍、面积约700 km~2的中酸性隐伏岩体—城南庄隐伏岩体。城南庄隐伏岩体边界基本与布格重力负异常边界吻合,呈长轴北东向宽缓带状展布,向南西方向倾伏,北侧埋深较浅、南侧埋深较深。城南庄隐伏岩体边部(特别是产状缓外倾,具有良好成矿空间的区域)和顶部与围岩的接触带位置、环形构造形成的晚期"小岩体"内部及附近位置和中酸性岩脉附近位置是寻找热液型矿床的有利部位。  相似文献   

朝鲜半岛平南盆地地质演化综述     

彭澎  胡波  张志越  张艳斌  郭敬辉  翟明国 《岩石学报》2021,37(1):129-142

平南盆地位于朝鲜半岛中部,处于华北克拉通(中朝克拉通)东缘;其演化历史长达10亿年,其地质记录为揭示东亚现今构造格局的形成提供重要制约。盆地发育中元古界-中生界,从下至上包括黄海群(1.3~1.1Ga)、祥原超群(1.0~0.9Ga,自下而上包括直岘群、祠堂隅群、默川群和灭岳山群等)、燕滩群(狗岘系,0.72~0.54Ga)、黄州系/超群(0.52~0.46Ga,包括下部黄州群和上部法洞群)和平安超群(0.33~0.24Ga)等5个构造层序;各单元之间均为平行不整合;沉积跨度超过10亿年,沉积物厚度累计达到15000m。另外,平南盆地南部发育临津群(0.42~0.35Ga),该地层与中元古界上部-奥陶系很可能呈构造接触关系。平南盆地沉积中心自中元古代晚期从南部逐渐向北部转移,新元古代及早古生代均位于中部,二叠纪盆地沉积中心位于北部。平南盆地沉积碎屑锆石年龄则显示物源发生多期变化:中元古代以盆地北侧基底~1.8Ga峰期岩浆-变质作用岩石为主;中元古代晚期以同沉积就位的岩浆岩为主;新元古代以1.6~1.5Ga和1.2~1.1Ga峰期的岩浆岩为主;寒武纪以~2.5Ga和~1.8Ga峰值的变质基底岩石为主。以上变化反映了古地理格局的显著变化。推测新元古代早期及之前,华北克拉通曾与某个发育1.6~1.5Ga和1.2~1.1Ga岩浆作用的克拉通或者岩浆弧相邻(近邻或远邻);地层记录了迄今所知新元古代最早的碳同位素负漂移(默川负漂移,~0.92Ga),地层可能还记录了最晚的负漂移(燕滩负漂移,可能对应全球Gaskiers负漂移,~0.55Ga),它们可能是对新元古代全球长期多次岩浆-裂解-冰期事件的响应。  相似文献   

河西走廊西段花海断裂几何学、运动学及区域构造意义          下载免费PDF全文

云龙  张进  徐伟  刘志成  张竞嘉  赵衡  张北航 《地球科学》2021,46(1):259-271

花海断裂位于河西走廊西段花海盆地内,总体走向NNW-SSE,长约38 km,为一条隐伏断裂,研究其空间展布、运动性质和活动历史对于理解青藏高原北缘的构造变形和扩展方式有重要意义.基于卫片解译、野外实地和槽探,结合光释光测年和地球物理资料,发现沿双泉子、大泉至小泉一带,发育一段长约8 km的地形陡坎,代表断裂控制下褶皱作用的地形表现.沿陡坎走向向南,断裂一直隐伏延伸至宽滩山和黑山以北.现有资料分析表明,断裂经历了早白垩世的正断、晚白垩的逆冲运动.新生代以来,断裂继承了之前的逆冲运动并一直持续至全新世中晚期.高原北缘的侧向扩展,使得作为三危山与阿尔金断裂之间块体边界的三危山、干峡山、宽滩山和塔尔湾-登登山-池家刺窝断裂发生以左旋走滑为主兼有逆冲的变形,导致了边界断裂控制山体的隆升,而内部的块体受压剪作用向北东运动.花海断裂的逆冲运动即是该次构造活动事件的响应.   相似文献   

准噶尔盆地南缘西段中、上侏罗统沉积演化及控制因素分析          下载免费PDF全文

张驰  于兴河  姚宗全  李顺利  单新  向曼  李亚龙 《中国地质》2021,48(1):284-296

针对准噶尔盆地南缘中、上侏罗统沉积体系演化控制因素不清、沉积模式不明等问题,通过对多条露头剖面精细解剖、详尽写实沉积特征描述等手段,分析了其垂向序列、砂体叠置方式、水动力条件、沉积体系演化及控制因素。研究表明准南中、上侏罗统自下而上分别发育辫状河沉积、曲流河沉积和扇三角洲沉积,古气候与构造造成的水动力条件的变化是控制这种沉积演化的主要因素。其中头屯河组底部发育辫状河沉积,古气候温暖湿润,形成堆叠型砂体叠置方式;中部发育辫-曲转换沉积,古气候开始初步干旱,形成紧密叠置型砂体;上部发育曲流河沉积,降雨量较少古气候干旱,形成孤立河道型砂体。齐古组发育季节性曲流河沉积,古气候较为干旱,在湿润期降雨量较充足时发育侧向迁移型砂体,干旱期则发育侧向连片型砂体。喀拉扎组发育扇三角洲沉积,古气候整体炎热干旱,构造活动剧烈,碎屑水道在扇三角洲平原构成垂向切割型砂体,而前缘水下分流河道则构成侧向切割型砂体。  相似文献   

巴布亚湾两期前陆盆地叠置结构及其形成演化          下载免费PDF全文

王德良  梅廉夫  胡孝林  杨松岭  吴路路  刘昭茜  杨焓  苏珈毅 《地球科学》2021,46(2):405-417

巴布亚湾受澳大利亚板块与太平洋板块高速斜向汇聚的控制,经历了复杂的中、新生代构造演化.前人对巴布亚湾盆地结构构造特征的研究多是局部的、分散的,关于盆地的形成时间和动力学机制仍存在争议.利用覆盖全盆的钻井约束的高精度2D、3D地震资料,精细地刻画了盆地的结构和构造特征,揭示了巴布亚湾发育潘多拉和奥雷两期叠置的前陆盆地.潘多拉前陆盆地是形成于渐新世不整合面之上的晚渐新世-中中新世微型前陆盆地,走向为NNE.奥雷前陆盆地是发育在复杂的裂谷边缘之上的早中新世-现今的周缘前陆盆地,沿着弧形的巴布亚半岛延伸480 km;盆地走向在148°E发生转变,由西部的NW向转为东部的近EW向.潘多拉微前陆盆地被奥雷前陆盆地向南逐渐超覆的沉积地层覆盖,两个前陆盆地走向相互垂直,垂向上形成叠置结构.阐明了巴布亚湾新生代经历三期挤压事件及两期叠置的前陆盆地的形成演化,解决了盆地结构及区域构造演化认识的不足,理清了复杂陆缘环境从伸展到挤压多期构造事件的时序及动力学机制,为澳大利亚板块北缘的板块构造重建提供了盆内证据.   相似文献   

思茅地块西缘大凹子组地层序列及地质时代          下载免费PDF全文

魏月华  甘正勤  刘桂春  冯庆来 《地球科学》2021,46(2):418-431

目前关于思茅地块西缘大凹子组的形成时代仍有分歧.在思茅地块西缘大中河剖面采集了硅质岩、砂岩、凝灰岩和玄武岩,通过放射虫组合和锆石U-Pb年龄方法,厘定其地质时代,并结合区域资料恢复地层序列.通过详细剖面实测,发现该剖面由6个地层断片组成:第一、四断片以含放射虫硅质岩为特征,放射虫组合指示其时代为晚泥盆世至早石炭世早期;第二、五断片以火山碎屑岩、具有鲍玛序列沉积特征的火山碎屑沉积岩为主,锆石U-Pb同位素年龄指示其时代为志留纪中期至早泥盆世;第三、六断片以火山岩沉积为特征,锆石U-Pb同位素年龄指示其时代为志留纪早期.结合前人资料认为思茅地块西缘分布的海相火山岩、碎屑岩和含放射虫硅质岩地层层序代表了志留纪到早石炭世早期的岛弧火山-沉积地层序列.   相似文献