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1.
华南花岗岩型铀矿床成矿热源的分析和计算 总被引：5，自引：0，他引：5
木文在分析研究华南花岗岩型铀矿床成矿地质特征的基础上,根据JJ花岗岩体的规模(340km~3)、放射性元素含量(U 11ppm, Th 50.2ppm,K 4.4％)及围岩导热率(K_m=2.51×10~(-2)Jcm~(-1)℃~(-1)),计算得出JJ岩体由于放射成因热的积累可在其周围形成温度为323℃(岩体中心)—167℃(距岩体3.73km(水平)和7.87km(垂直))的稳定热场。笆者认为,放射成因热是华南花岗岩型铀矿床的主要成矿热能来源。 相似文献
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锆石的U-Pb测年、Hf和O同位素及稀土、微量元素的研究与应用已获得诸多进展,但锆石中铀含量所蕴藏的地质意义却较少被关注。华南花岗岩型铀矿床的铀源一直存在争议,不同观点认为其分别来自早期已固结地质体、分异岩浆、地幔柱或热点以及U、Th、K富集圈。为尝试利用锆石中的铀含量来追索铀源,本文通过搜集诸广山南体花岗岩锆石U-Pb同位素测年文献,掌握了该花岗岩中14个岩体、37件样品、3种岩性,共467个锆石定年数据。通过数据分析发现印支期(253Ma、244Ma)和燕山期(139Ma、124Ma)具高分异特征的4件酸性岩脉(小岩体)样品中锆石的铀含量明显高于同期岩体。依据铀矿床中高分异酸性岩脉(小岩体)侵位期、基性岩脉侵位期、铀成矿早期(140~90Ma)三者的良好对应关系,结合这一锆石铀含量指示,初步认为华南花岗岩型铀矿床中铀可能主要来自高分异花岗岩浆;推测花岗岩型铀成矿可能属壳幔混合作用结果,即铀源来自地壳分异岩浆,成矿流体和矿化剂主要来自地幔,而成矿空间受断裂系统控制。岩体锆石铀含量或可在铀源丰度、矿床品位判别等方面发挥积极作用。 相似文献
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花岗岩型铀矿床是我国最重要的铀矿床类型之一,且主要分布在华南地区。本文在简要介绍华南花岗岩型铀矿床主要地质特征的基础上,重点总结了华南花岗岩型铀矿床的产铀花岗岩、成矿时代、成矿流体和成矿物质来源等方面的研究进展。华南花岗岩型铀矿床主要分布在华夏地块,以桃山-诸广铀成矿带最为重要。矿床以中小型(300～3000t U)和中低品位(0.05%～0.2%U)为主。产铀花岗岩主要形成于三叠纪(240～205Ma)和侏罗纪(165～150Ma)两个时期,属于S型花岗岩,源区以泥质沉积岩为主。三叠纪过铝质淡色花岗岩是有利的铀源岩,其中铀主要赋存于晶质铀矿。黑云母、晶质铀矿、磷灰石和锆石成分特征是评价花岗岩产铀潜力的有效工具。华南大多数花岗岩型铀矿床形成于白垩纪-古近纪(110～50Ma),以后生热液成因为主,其形成主要与区域白垩纪-古近纪岩石圈伸展作用和幔源基性岩浆活动有关。成矿流体以大气降水为主,成矿温度集中在120～260℃、盐度一般小于10%NaCleqv,铀在流体中主要以铀酰碳酸络合物和铀酰氟化物形式迁移,物理化学条件变化和CO_2去气导致铀在有利部位沉淀。文章指出应加强花岗岩中铀活化机制、铀成矿时代、以及下庄铀矿田侏罗纪(175～145Ma)铀成矿作用研究。 相似文献
4.
302铀矿床方解石C-O同位素组成与成矿动力学背景研究 总被引：8，自引：0，他引：8
302铀矿床规模大,垂幅深(达1000多米),是我国华南主要产铀花岗岩型铀矿床之一。研究表明该矿床的方解石是经大气降水与围岩发生水岩反应后的流体去气沉淀的;矿化剂∑CO2主要源自受控于岩石圈伸展导致的地幔去气,对铀成矿的作用一方面表现为加入到贫矿化剂的地下水中以便铀元素迁移,另一方面表现在从成矿流体中逸出,改变热液络离子组成,导致铀沉淀成矿;印支碰撞运动使华南地壳叠加增厚,部分熔融含铀结晶基底,为产铀岩体提供丰富的成矿物质来源;白垩纪-古近纪地壳拉张、岩石圈伸展所形成的深大断裂等不仅是矿化剂∑CO2主要通道,而且还是控制铀矿床形成的关键因素。 相似文献
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本文以我国华南典型花岗岩型铀矿床-棉花坑(302)铀矿床的γ测井资料为对象开展γ测井解译方法的研究。成果表明:特征参数α是三点式反褶积分层解释法合理解译铀矿层厚度及其含量的关键因素;当铀矿层厚度较大、铀品位较高时,三点式反褶积分层解释法和平均含量法对矿体厚度及其铀含量解释结果接近;三点式反褶积分层解译法解译矿段厚度具有截距误差,解译铀含量可能出现零值或负值;三点式反褶积分层解译法在矿体(矿段)薄、铀含量低、矿体厚度变化大、铀含量变化大的情况下,解译华南花岗岩型铀矿需考虑邻近岩矿石产生的γ射线影响。 相似文献
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华南是我国花岗岩型铀矿主要产地。通过对华南地区不同类型花岗岩型铀矿区域地质背景、成矿作用特征、铀成矿机理以及控矿因素的综合分析, 认为华南不同类型花岗岩型铀矿床成矿作用具有相似性, 铀成矿具有多期、多阶段特征, 成矿物质铀主要来自富铀基底和花岗岩, 成矿流体具有壳源和幔源流体成分。花岗岩型铀矿属于深源地幔流体和大气降水共同参与的复成因成矿作用的产物, 断裂构造是最关键的控矿因素, 受控于中新生代岩石圈伸展作用。在此基础上, 构建了华南地区区域铀成矿模式和预测评价模型, 预测了重点地区富大铀矿成矿远景区4片, 基于GOCAD软件开展了书楼丘、鹿井、沙子江矿床三维地质模型构建和深部铀成矿预测, 实现了“定型、定位、定深、定量”预测, 为华南地区下一步铀矿找矿工作部署提供了科学依据。 相似文献
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华南陆壳改造系列花岗岩类型划分和成岩物质来源 总被引：43，自引：3，他引：43
本文将华南陆壳改造系列花岗岩进一步划分为同造山混合花岗岩和岩浆花岗岩型、非造山陆壳重熔型和同碰撞型3类。根据锶、钕同位素测定值,依壳、幔二元混合模型方法计算了3类花岗岩源区物质的构成:第一类型为上壳端元占78.6—89.7％,亏损地幔端元占15.0—10.3％;第二类型为上壳端元占63.7％,亏损地幔端元占36.3％;第三类型上壳端元占100％。均以上壳端元为主。 相似文献
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江西省早古生代晚期花岗岩的地球化学特征及其地质意义 总被引：6，自引：2，他引：4
上犹、陡水、龙回和乐安岩体是江西省早古生代晚期花岗岩的重要组成部分。它们具有较高的S iO2含量(平均73.80%)、K2O/Na2O比值(平均为1.33)和ACNK值(平均为1.05);大离子元素明显富集,Ba、Sr、P、Ti负异常明显;轻稀土元素富集(LREE/HREE比值平均为6.78),Eu亏损相对明显(δEu值平均为0.39)。同时,它们具有稍高的εNd(t)值(平均为-5.7)和相对年轻的Nd模式年龄(平均为1617M a)。它们在ACF和(La/Yb)N-δEu图解中,投影于S型或壳源型花岗岩范围内;在εNd(t)-t图解中,位于华南元古代地壳演化域内;在Rb/Sr-Rb/Ba和A/MF-C/MF图解中,它们的源区物质是泥质岩和砂质岩而不是幔源基性岩;此外,在研究区域内,迄今未发现早古生代幔源岩浆活动。这些特征表明,研究区内早古生代晚期花岗岩应归属于S型或壳源型花岗岩。其形成机制与早古生代晚期的板内作用有关,即早先受区域挤压应力场影响,武夷、南岭、赣中等块体彼此拼贴,进而增生到扬子地块之上;稍后,由于应力场的转化,进入后碰撞伸展环境。并在减压、导水等因素的综合影响下,位于中、上地壳层位的低成熟度泥砂质碎屑岩发生部分熔融,形成S型或壳源型花岗岩。 相似文献
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华南地区新元古代花岗岩铀成矿机制——以摩天岭花岗岩为例 总被引：3，自引：3，他引：0
华南是我国重要的花岗岩型铀成矿区,印支期-燕山期花岗岩是最主要的产铀花岗岩。广西北部形成于新元古代的摩天岭岩体是我国目前已知的最古老的产铀花岗岩体之一。前人对华南印支-燕山期花岗岩的铀成矿作用研究较深入,但对以摩天岭岩体为代表的新元古代古老花岗岩的铀成矿作用研究程度较低。本文以摩天岭花岗岩体为对象,进行了岩石学、地球化学、年代学及其铀矿成矿特征和规律的深入研究,取得以下认识:1)摩天岭岩体规模巨大,相带分布明显,内部相带和过渡相带发育,岩性主要为黑云母花岗岩、二云母花岗岩和含电气石二云母花岗岩,花岗岩体具有富硅富碱、铝过饱和、钾大于钠的特点,属S型花岗岩; 2)摩天岭岩体形成于850～760Ma之间的新元古代; 3)摩天岭岩体铀成矿潜力巨大,铀矿化以铀-绿泥石型和铀-硅化带型为主,铀-绿泥石型的代表矿床——达亮矿床形成于360～401Ma,是加里东期区域变质及构造活动共同作用的结果;铀-硅化带型铀矿的代表——新村铀矿形成于47Ma,是喜马拉雅期伸展构造作用下构造-热液活动共同作用的结果; 4)摩天岭岩体中铀矿床的铀源来自于元古界四堡群、丹州群和摩天岭岩体本身;成矿流体主要来源于大气降水,同时有深部流体的参与;热源主要与加里东期区域变质作用和喜马拉雅期伸展背景下的构造作用关系密切; 5)摩天岭岩体铀成矿经过了新元古代铀预富集、加里东晚期到海西早期的区域变质-构造热液成矿作用、喜马拉雅期的构造热液成矿作用等几个阶段,形成了类型丰富、规模较大的铀矿床,铀找矿潜力巨大。 相似文献
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Guboglo M. N. 《GeoJournal》1980,4(1):53-58
International unity is becoming ever stronger in this country owing to an increasing similarity in the development of the cultural environment. This comprises the provision of all the country's republics with a sufficient number of schools, theatres, and other institutions and cultural information media in accordance with the needs of the population. An important part is played by the rise in ‘the general educational level, as well as the level of professional qualifications and skills. Among all the Soviet nations and nationalities, this rise being more rapid among formerly backward peoples. Prominent among the factors of internationalization is the progressive development of the nationalities’ cultural resources, while professional culture is being increasingly brought within the reach of the masses.The implementation of the nationalities policy promotes the all-round development of all Soviet nations and nationalities, their drawing together, the upsurge of the individual capabilities of every Soviet citizen. 相似文献
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Jiayu Rong Michael Melchin S. Henry Williams Tatyana N. Koren Jacques Verniers 《《幕》》2008,31(3):315-318
The Global Stratotype Section and Point （GSSP） for the base of the Silurian System was defined in 1985. Since that time, a number of researchers have suggested that this section has serious deficiencies for use as a GSSP. As a result, in 2000, the Subcommission on Silurian Stratigraphy （SSS） proposed undertaking a formal restu@ of this GSSP, which was subsequently approved by the International Commission of Stratigraphy （ICS）. The result of this restudy was the formal proposal that the current GSSP, at 1.6 m above the base of the Birkhill Shale, at Dob＇s Linn, Scotland, should be maintained as the same locality and stratigraphic level, but the bios- tratigraphical definition of the boundary should be revised. The previously defined, basal Silurian grapto- lite zone, the Parakidograptus acuminatus Zone, should be subdivided into a lower Akidograptus ascensus Zone and a higher E acuminatus Zone. The base of the A. ascensus Zone, marked by the first appearance of A. ascensus, should be regarded as the biostratigraphic mark for the base of the Silurian. This proposal has now been formally approved by the SSS and ICS, and ratified by International Union of Geological Sciences. This is the first GSSP to undergo formal restudy and redefini- tion, and the proposal also included a recommended procedure for restudy of GSSPs. 相似文献
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Deviation of the major axis of the inertia ellipsoid of the Moon from the direction toward the Earth
B. P. Kondratyev 《Astronomy Reports》2017,61(8):709-714
It is known from observations that the center of mass of the Moon does not coincide with the geometric center of its figure, and the line connecting these two centers is not aligned with the direction toward the center of the Earth, instead deviating toward the Southeast. This stationary deviation of the axis of the inertia ellipsoid of the Moon to the South of the direction toward the Earth is analyzed. A system of five linear differential equations describing the physical libration of the Moon in latitude is considered, and these equations are derived using a new vector method taking into account perturbations from the Earth and partly from the Sun. The characteristic equation of this system is obtained, and all five oscillation frequencies are found. Special attention is paid to the fifth (zero) frequency, for which the solution of the latitude libration equations are stationary and represents a previously unknown additional motion of the rotational axis of theMoon in a cone with a small opening angle. In contrast to the astronomical precession of the Earth, the rotation of the angular-velocity vector is in the positive direction (counter-clockwise), with the period T 3 = 27.32 days. On this basis, this phenomenon has been named “quasi-precession.” This quasi-precession leads to a stationary inclination of the major axis of the inertia ellipsoid of theMoon to the South (for an observer on Earth), making it possible to explain one component of the observed deviation of the center of mass of the Moon from the direction toward the Earth. The opening angle of the quasiprecession cone is approximately 0.834″. 相似文献
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东濮凹陷北部沙三中亚段广泛发育盐岩和烃源岩,这两个看似不能共存的物质却在这里互层共生。该时期研究区沉积特征为多盐韵律与多层烃源岩互层共生、连续沉积,单个盐韵律厚度从几米到十几米,烃源岩有机质丰度高、类型好。平面上,两者在湖盆沉积沉降中心共生;垂向上,高有机质丰度、好干酪根类型与高盐度地层具有较好的对应关系。因而成为恢复古气候和古环境的重要研究对象。通过岩石学、古生物学以及Sr/Ba、B/Ga、(V+Ni+Mn)、Fe/Mn、Sr/Cu、Mg/Ca、V/(V+Ni)、稀土元素含量和氯同位素等方法对凹陷北部沙三中亚段的沉积环境进行研究。结果表明,凹陷北部沙三中亚段为深水沉积的还原环境,古盐度较高,达到半咸水-咸水沉积;微量元素和孢粉化石特征表明研究区沙三中亚段为温暖潮湿的环境。 相似文献
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Important tendencies in development of the world mineral-resources sector at the beginning of the 21st century were an increase in production and consumption of mineral materials differentiated by types of metals and nonmetallic mineral raw materials, by countries and regions, as well as the concentration of the production of mineral raw materials in a small number of countries, and a reduction in industrial reserves of minerals in the world economy, even at the current stage of their extraction. These tendencies should be taken into account in working out a strategy for development of the Russian mineral raw-material base. 相似文献
18.
Fouad N. Ibrahim Dr. 《GeoJournal》1988,17(1):133-141
Taking the example of W Sudan, an analysis of the climatic incidents leading to the two recent famine disasters is made. On this natural background, the human side is investigated. Focus is directed towards the fragile economic structure of the famine-prone population groups. An early-warning system for famine in the Sahelian Zone is proposed taking grain production and storage, livestock development and the relationship between the prices of livestock and grain as major indicators. 相似文献
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郯庐断裂南段研究进展与断裂性质讨论 总被引：13，自引：3，他引：13
据1：5万区域地质调查和专题研究资料，就郯庐断裂带是否南延与消失的原因，其与大别—苏鲁造山带交截形成的假位错效应，以及与中新生代沉积盆地形成演化的关系等作了新的阐述。在此基础上，讨论了郯庐断裂带是否为巨大的左行平移断层或转换断层。认为郯庐断裂带可能是在“古郯庐带”的基础上于早侏罗世重新活动、白垩纪强烈活动的地堑型枢纽断裂带。 相似文献
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The Importance of the Precipitation and the Susceptibility of the Slopes for the Triggering of Landslides Along the Roads 总被引：3，自引：1，他引：2
Clemente Irigaray Francisco Lamas Rachid El Hamdouni Tomás Fernández José Chacón 《Natural Hazards》2000,21(1):65-81
In order to characterise the influence of the heavyrains on the observed landslides during the 1996–1997hydrological cycle, rainfall records for the last 100years are analysed from 104 stations in easternAndalusia. Regarding the amounts of rain recordedbetween October 1996 and March 1997 in the 104stations studied, 31 presented new all-time records;15 presented values that were 80–100% of thepre-1995 record; 49 stations, 80–50%; and 9stations, < 50%. A map has been devised of thesusceptibility of the materials through which thesouth-eastern Andalusian road network crosses,together with an inventory of the damage caused byinstability phenomena on banks and cuttings of theroad network during the winter of 1996–1997. Therelationships between the rainfall during the studyperiod, the damage caused to the road network and thesusceptibility of the materials affected are analysed.The results indicate that there is a clearcorrespondence between the rainfall recorded and thesusceptibility of the materials with the inventorieddamage. It is concluded that the widespread seriousdamage caused in early 1997 to the roads andsurrounding areas in the Alpujarra region and thecoast of the Province of Granada was mainly caused bythe extraordinarily heavy rains. However, considerablyless damage was observed where the susceptibility ofthe terrain is low, thus highlighting the extremeusefulness of terrain-susceptibility maps for riskprevention and territorial planning. 相似文献