郯庐断裂带苏皖段重力变化的多尺度分解与构造活动分析     

林承灏  黎哲君  徐如刚  袁泉 《大地测量与地球动力学》2019,39(9):884-889

基于多期绝对重力与相对重力联测资料，获取不同时空尺度的郯庐断裂带苏皖段及周边地区重力场动态变化，采用小波多尺度分解方法计算不同深度的重力变化，结合区域地质构造，从深度层次的横向变化与时间尺度的纵向变化2个方面进行分析。结果表明，研究区重力变化主要由中、上地壳密度变化或断裂构造活动引起。沿郯庐断裂带苏皖段走向断裂活动分布不均，受周边深大断裂带交切作用的影响表现出明显的分段活动特征。淮阴-响水口断裂、滁河断裂等深大活动断裂带构造活动对局部重力变化具有一定的控制作用，沿断裂带走向分布有明显的重力变化梯度带；郯庐断裂带郯城-泗县段、大别山构造带霍山-六安及江苏溧阳-镇江地区在小波细节动态变化中存在重力变化梯度带异常区，但强度不高，考虑到多条深大断裂交切于此，后期需要重点关注。  相似文献   

龙泉山断裂带断层最新活动年代及方式     

刘亮  梁斌  燕中林  苏画  何学锋 《中国地质调查》2020,7(5):77-87

龙泉山断裂带属龙门山前陆隆起,与青藏高原龙门山的隆升演化密切相关。为探讨龙泉山断裂带断层活动方式、期次及年代特征,在该断裂带不同部位采集了断层泥样品,通过扫描电镜(SEM)对样品中的石英颗粒进行了痕迹微形貌和溶蚀微形貌观察,通过电子自旋共振(ESR)测试了样品断层的最新活动年龄,并结合区域地震资料,进一步研究了龙泉山断裂带断层的发震潜力。结果表明: 龙泉山断裂带断层运动方式以黏滑为主,兼蠕滑; 具有多期次活动特征,强烈活动时间为早更新世—中更新世,晚更新世也有明显断层活动,全新世断层活动不明显; SEM 、ESR、热释光(TL)测得的断层最新活动年龄为(1 210±121)~(110±10.0) ka; 最新活动年代和活动性具有分段性,中段断层活动性较弱,北段和南段断层活动性较强。总之,龙泉山断裂带为1条活动性断裂带,具有一定的发震潜力,地震沿断裂带呈带状分布,但相比其西侧的龙门山断裂带,其活动性已大大降低。  相似文献   

A high-precision heuristic model to detect home and work locations from smart card data     

Nilufer Sari Aslam  Tao Cheng  James Cheshire 《地球空间信息科学学报》2019,22(1):1-11

Smart card-automated fare collection systems now routinely record large volumes of data comprising the origins and destinations of travelers. Processing and analyzing these data open new opportunities in urban modeling and travel behavior research. This study seeks to develop an accurate framework for the study of urban mobility from smart card data by developing a heuristic primary location model to identify the home and work locations. The model uses journey counts as an indicator of usage regularity, visit-frequency to identify activity locations for regular commuters, and stay-time for the classification of work and home locations and activities. London is taken as a case study, and the model results were validated against survey data from the London Travel Demand Survey and volunteer survey. Results demonstrate that the proposed model is able to detect meaningful home and work places with high precision. This study offers a new and cost-effective approach to travel behavior and demand research.  相似文献   

Application of Markovian models for non-ergodic and non-stationary earthquake times series for the identification of seismic patterns and future projections*          下载免费PDF全文

Hakan Karaca 《地震科学（英文版）》2020,33(2):98-106

The current earthquake forecast algorithms are not free of shortcomings due to inherent limitations. Especially, the requirement of stationarity in the evaluation of earthquake time series as a prerequisite, significantly limits the use of forecast algorithms to areas where stationary data is not available. Another shortcoming of forecast algorithms is the ergodicity assumption, which states that certain characteristics of seismicity are spatially invariant. In this study, a new earthquake forecast approach is introduced for the locations where stationary data are not available. For this purpose, the spatial activity rate density for each spatial unit is evaluated as a parameter of a Markov chain. The temporal pattern is identified by setting the states at certain spatial activity rate densities. By using the transition patterns between the states, 1- and 5-year forecasts were computed. The method is suggested as an alternative and complementary to the existing methods by proposing a solution to the issues of ergodicity and stationarity assumptions at the same time.  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   

内蒙古黄岗梁铁锡矿床中红色萤石的地球化学特征及成因探讨     

陈缘  韩禹  许博  刘金高 《岩石学报》2021,37(12):3869-3879

内蒙古黄岗梁萤石呈现稀有的红色特征,该颜色萤石全球产量稀少,本文利用LA-ICP-MS原位测试技术对其微量元素地球化学特征进行了系统分析,探讨黄岗梁铁锡矿床中红色萤石的成因。微量元素分析结果显示黄岗梁萤石样品中总稀土元素含量较低,并表现出左倾的富集重稀土特征,其中红色和粉色萤石的稀土元素配分曲线显示出Dy-Tm拱顶式凸起的配分模式,表明其结晶作用发生在成矿流体演化的最后阶段;Y/Ho比值104~197,与热液成因萤石一致,且La/Ho比值为0.027~0.126,具强的负异常,表明了黄岗梁萤石为热液成因;Ce/Ce^*比值0.57~0.98,Eu/Eu^*比值0.22~0.63,均表现出负异常,表明形成黄岗梁萤石的热液流体是在相对还原环境下形成且温度高于200℃。综合分析萤石的地球化学特征和其与围岩的接触关系,认为黄岗梁萤石主要分为两阶段结晶,一阶段为与石英同期结晶形成红色、粉色部分,二阶段为在石英形成后结晶形成的由阳起石他色致色的绿色部分,而黄岗梁萤石罕见的红色是由于Y元素较为富集且含量远高于其他稀土元素,从而形成YO₂色心并在萤石中作用而显色。  相似文献   

新疆阿尔泰可可托海伟晶岩型稀有金属矿床中磷灰石地球化学特征及意义     

白应雄  申萍  曹冲  潘鸿迪  李昌昊  罗耀清  冯浩轩  索青宇 《岩石学报》2021,37(9):2843-2860

磷灰石可以记录和保存岩浆和热液活动的信息。可可托海伟晶岩型稀有金属矿床磷灰石发育,为研究该矿床伟晶岩成岩成矿过程提供了优良的条件。已有对可可托海伟晶岩型稀有金属矿床磷灰石的研究集中在其稀土元素特征,较少讨论其对伟晶岩成岩成矿过程的制约。本文选取可可托海伟晶岩型稀有金属矿床富矿伟晶岩脉(3号脉)和相对贫矿伟晶岩脉(1号、2b号和3a号脉)中的磷灰石作为研究对象,进行磷灰石岩相学和地球化学研究。岩相学分析表明,磷灰石主要与钠长石、石英、白云母、锰铝榴石等伴生。EPMA分析显示,磷灰石F含量为3.67%～4.41%,Cl含量小于0.67%,较低的Cl含量表明伟晶岩熔体出溶的流体Cl含量较低;大部分磷灰石MnO含量为4.67%～8.71%,但2b号脉磷灰石MnO含量变化较大(1.23%～14.28%),这是由于2b号脉磷灰石具有分带结构,暗示其遭受后期热液作用,促使磷灰石溶解-再沉淀,导致MnO含量发生较大变化。LA-ICP-MS分析显示,贫矿伟晶岩脉磷灰石的稀土元素含量较低(180×10~(-6));相反,富矿伟晶岩脉磷灰石的稀土元素含量较高( 700×10~(-6)),并具有明显的四分组效应(TE_(1-3)平均值为1.7)。1号脉和3a号脉磷灰石均显示轻稀土元素富集,反映其形成过程中有含Cl热液的参与。3号脉磷灰石显示强烈Eu负异常和Ce正异常,而2b号脉磷灰石显示强烈Ce负异常和中等Eu负异常,这种Eu、Ce异常的差异可能与岩浆-热液阶段大量流体出溶密切相关。磷灰石的沉淀将导致热液中HF含量的降低,促使磷灰石周围铌钽矿结晶和Nb、Ta进入磷灰石中。可见,在伟晶岩形成过程中,磷灰石并非保持稳定,其分带结构和主微量成分变化记录了后期热液活动,暗示后期热液活动对伟晶岩的成矿具有重要作用。  相似文献   

金川铜镍硫化物矿床中铂族矿物的主要类型和产出特征:热液蚀变过程中铂族元素的富集机理     

董宇  魏博  王焰 《岩石学报》2021,37(9):2875-2888

金川铜镍硫化物矿床是我国最主要的铂族元素(PGE)资源产地,其矿石受热液蚀变作用影响明显,并产出多种铂族矿物(PGM)。岩浆演化和热液蚀变过程中PGE的迁移富集机制和PGM的成因,一直是研究PGE地球化学行为非常关注的问题。本文对金川铜镍硫化物矿床中PGM的研究发现,其主要类型包括含PGE的硫砷化物(硫砷铱矿)和砷化物(砷铂矿),Pd的铋化物、碲化物和硒化物,以及少量其他铂族矿物。其中,硫砷铱矿可包裹于各种贱金属硫化物(镍黄铁矿、磁黄铁矿和黄铜矿)中,表明硫砷铱矿可能结晶于早期的含As硫化物熔体,随后被包裹于硫化物熔体冷凝分异产生的单硫化物固溶体(MSS)和中间硫化物固溶体(ISS)中。硫化物熔体中的As可能主要通过地壳混染作用加入幔源岩浆。大量铋钯矿(PdBi)呈微细乳滴状包裹于黄铜矿中,为晚期ISS冷凝形成黄铜矿过程中出溶的产物。少量铋钯矿(PdBi_2)呈不规则状充填于矿物裂隙,与次生磁铁矿脉紧密共生,并随矿石的蚀变程度增加,铋钯矿的化学成分由PdBi逐渐向PdBi_2转变,表明这部分铋钯矿为后期热液蚀变产物。铋碲钯矿和钯的硒化物则主要产出于镍黄铁矿裂隙且与次生磁铁矿紧密共生,指示明显的热液成因。钯的硒化物的出现表明,岩浆期后酸性、高盐度、高氧逸度的富Cl~-流体对金川铜镍硫化物矿床中Pd的迁移和富集起到了关键控制作用。  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   

火山活动与海侵影响下的典型湖相页岩有机质保存差异分析   总被引：1，自引：0，他引：1  

李鹏  刘全有  毕赫  孟庆强 《地质学报》2021,95(3):632-642

黑色富有机质页岩是页岩油气生成和赋存的主要母体,是强还原环境水体的沉积产物,在其形成过程中,细菌硫酸盐还原作用(BSR)对水体环境影响明显,但BSR强度如何影响有机质的保存尚未得到关注。我国陆相湖盆富有机质泥页岩广泛发育,形成过程中常常伴随有火山活动或者海侵等事件,大量硫酸盐进入湖盆,改变水体的沉积环境,不同环境下BSR对黑色页岩有机质保存的影响明显不同。本次研究选取鄂尔多斯盆地延长组长7段页岩、松辽盆地青山口组和嫩江组页岩作为对象,同时与现代沉积物进行对比。研究表明,TOC与TS之间关系复杂,但细菌硫酸盐还原强度指数(SRI)与TOC呈现幂指数变化,且表现出两阶段变化的特征。当SRI大于1.375时,TOC整体偏低,指示了强硫酸盐还原作用消耗大量有机质;当SRI小于1.375时,TOC明显较高,指示了弱硫酸盐还原作用对有机质消耗相对较少,更有利于有机质保存。火山活动和海侵作用均向水体提供了大量硫酸盐,但对陆相湖盆页岩中有机质的保存影响不同。火山活动影响的长7段页岩SRI普遍小于1.375,BSR对有机质消耗相对弱,页岩TOC高。而受海侵影响的青山口组一段底部和嫩江组一段底部页岩SRI大于1.375,BSR过度消耗了大量有机质,使得页岩TOC偏低。嫩江组一段下部SRI指数更高,海侵强度更大,BSR反应更强,更不利于有机质保存。  相似文献