Outburst of the X-ray transient SAX J1818.6-1703 detected by the INTEGRAL observatory in September 2003     

S. A. Grebenev  R. A. Sunyaev 《Astronomy Letters》2005,31(10):672-680

During the observation of the Galactic-center field by the INTEGRAL observatory on September 9, 2003, the IBIS/ISGRI gamma-ray telescope detected a short (several-hours-long) intense (～380 mCrab at the peak) outburst of hard radiation from the X-ray transient SAX J1818.6-1703. Previously, this source was observed only once in 1998 during a similar short outburst. We present the results of our localization, spectral and timing analyses of the object and briefly discuss the possible causes of the outburst. The release time of the bulk of the energy in such an outburst is appreciably shorter than the accretion (viscous) time that characterizes the flow of matter through a standard accretion disk.  相似文献   

内蒙古沙章土锡铜多金属矿床成矿年代学及成因探讨     

吕云鹤  董国臣  吕书俊  李洪宾 《矿床地质》2023,42(2):396-410

沙章土锡铜多金属矿位于内蒙古中部,近年来区内锡矿找矿工作的新发现,锡矿体为呈脉状、浸染状分布的电气石脉、电英岩及电英岩化蚀变岩,含锡矿物主要为锡石;铜矿体为浸染状分布的黄铜矿化电英岩化蚀变岩、方铅矿-闪锌矿-黄铜矿化蚀变岩,含铜矿物主要为黄铜矿,同时,经由钻探工程在矿床深部发现有闪长玢岩岩体。为了查清锡铜矿体成矿年龄及成矿物质来源,明确矿床成因类型,进一步指导找矿工作,文章在野外调查和室内综合研究基础上,对锡石开展了LA-MC-ICP-MS U-Pb定年及电子探针分析工作,并对共生的硫化物进行了硫同位素测试。测试结果显示,锡石成矿年龄为(316.3±8.9)Ma,为海西期晚石炭世阶段的产物;探针数据显示其成因为热液型锡石;硫同位素测试结果,δ³⁴S值为0.43‰～7.34‰,平均值4.39‰,具混合硫源特征。综上所述,笔者初步认为沙章土锡铜矿床的成因类型是与闪长玢岩有关的岩浆热液型。  相似文献   

纵横波源下含油气薄储层地震响应特征的对比分析     

王雨杰  贺学铭  王志恒  屈洁  杨春 《地质论评》2023,69(Z1):429-432

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内蒙古林西县北三段银铅多金属矿床碳、氧、硫、铅同位素特征及成矿物质来源     

吕向光 《地质与勘探》2015,51(5):898-906

本文对内蒙古林西县北三段银铅多金属矿床矿体的碳、氧、硫、铅同位素进行了测定,并对其成矿物质来源及演化进行了探讨。矿区样品的δ34S‰变化范围为-0.24‰~2.37‰,平均值为1.29‰,初步认为矿石中的硫主要来源于深部岩浆,并有少量生物还原硫的加入。样品的δ13CPDB变化范围为-4.57‰~-7.33‰,平均值为-5.96‰,δ18O为-3.4‰~-4.8‰,平均值为-4.06‰;δ13CPDB-δ18OSMOW关系表明,矿体中的碳可能主要由基性-超基性岩浆提供,并有部分来源于地层,且受大气水影响明显。铅同位素表明北三段矿床的成矿物质可能由造山带物质和地幔物质两部分提供。  相似文献   

Geochemistry of the Eocene Jijuntun Formation oil shale in the Fushun Basin,northeast China: Implications for source-area weathering,provenance and tectonic setting     

《Chemie der Erde / Geochemistry》2015,75(1):105-116

Within the fault-bound Fushun Basin of northeastern China, the Eocene Jijuntun Formation hosts extensive deposits of thick lacustrine oil shale. Systematic sampling and geochemical analysis of these deposits has revealed that the parent rocks of the oil shale underwent moderate chemical weathering; and that its mineralogy and trace and rare earth element geochemistry were mainly controlled by parent rock composition, with no synsedimentary changes in the source terrain. Based on source rock and tectonic setting discrimination diagrams, we concluded that the parent rocks of the oil shale were mostly basalts of the Paleogene Laohutai Formation. These basalts originated in a continental back arc environment and contain abundant nutrient elements such as Fe, P, Ni, Cu and Zn, all of which are essential for the growth of aquatic photoautotrophs in lakes. Continuous, high primary productivity in the Jinjuntun lacustrine depocentre, combined with a stable tectonic setting and underfilled sedimentary environment, were key factors in the genesis of its oil shale.  相似文献   

大兴安岭林区负地闪电荷源的反演     

武智君  郄秀书  王东方  宣越健  刘明远  王志超 《气象学报》2013,71(4):783-796

在中国东北大兴安岭林区进行了基于全球定位系统(GPS)时间同步的闪电地面电场变化多站观测.利用2010年7月14日一次过境雷暴多站同步的闪电电场变化资料,采用非线性最小二乘拟合法对雷暴成熟阶段的15次负地闪(包含57次回击和8次连续电流过程)中和的电荷源进行了拟合.大兴安岭林区负地闪单次回击中和的电荷量平均为1.0C(范围为0.1-5.0C),20%的继后回击中和电荷量大于首次回击,继后回击与首次回击中和电荷量的比为0.1-6.1,平均为0.8±1.0.单次连续电流中和的电荷量平均为3.8C(范围为0.4-7.3C),连续电流期间通道中的平均电流估计为25.3A(范围4.9-50.8A),一次负地闪中和的总电荷量平均为6.4C(范围为1.4-12.4C).负地闪回击和连续电流中和电荷源的高度分布与雷暴云的发展有关,对应的环境温度为-10--25℃.在雷暴成熟阶段前期,负地闪回击和连续电流中和电荷源距地面的高度从5.0km缓慢上升至10.5km;在雷暴成熟阶段后期,负地闪回击和连续电流中和电荷源距地面的平均高度从9.0km下降到6.0km,单次回击中和的电荷量也较前期减小约一个量级.与雷达回波的叠加显示,负地闪回击和连续电流中和的电荷源主要位于大于40dBz的强对流中心区,部分位于30-40dBz的强回波区边缘或较弱的回波区.  相似文献   

Green functions and associated sources in infinite and stratified poroelastic media     

C. Boutin  G. Bonnet  P. Y. Bard 《Geophysical Journal International》1987,90(3):521-550

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Importance of soil surface characteristics on water erosion in a small grazed Sahelian catchment     

H. Karambiri  O. Ribolzi  J. P. Delhoume  J. Ducloux  A. Coudrain‐Ribstein  A. Casenave 《水文研究》2003,17(8):1495-1507

This study concerns the problem of water erosion in the Sahel. Surface water and sediment yields (suspended matter and bedload) were monitored for 3 years (1998–2000) at the outlet of a small grazed catchment (1·4 ha) in the northern part of Burkina Faso. The catchment consists of about 64% sandy deposits (DRY soil surface type), which support most of the vegetation, and about 34% of crusted bare soils (ERO soil surface type). The annual solid‐matter export is more than 90% suspended sediment, varying between 4·0 and 8·4 t ha^?1. The bedload represents less than 10% of soil losses. In a single flood event (10 year return period), the sediment yield can reach 4·2 t ha^?1. During the period studied, a small proportion (20 to 32%) of the floods was thus responsible for a large proportion (80%) of the solid transport. Seasonal variation of the suspended‐matter content was also observed: high mean values (9 g l^?1) in June, decreasing in July and stabilizing in August (between 2 and 4 g l^?1). This behaviour may be a consequence of a reorganization of the soil surfaces that have been destroyed by trampling animals during the previous long dry season, vegetation growth (increase in the protecting effect of the herbaceous cover) and, to a lesser extent, particle‐supply limitation (exhaustion of dust deposits during July). The particle‐size distribution in the suspended matter collected at the catchment outlet is 60% made up of clay: fraction ≤2 µ m. The contribution of this clay is maximum when the water rises and its kaolinite/quartz ratio is then close to that of the ERO‐type surfaces. This indicates that these surfaces are the main source of clay within the catchment. Copyright © 2003 John Wiley & Sons, Ltd.  相似文献   

X-ray bursts from the source A1742-294 in the Galactic-center region     

A. A. Lutovinov  S. A. Grebenev  M. N. Pavlinsky  R. A. Sunyaev 《Astronomy Letters》2001,27(8):501-506

We present observations of the X-ray burster A1742-294 near the Galactic center with the ART-P telescope onboard the Granat observatory. The shape of its persistent spectra was described well by the model of bremsstrahlung from optically thin plasma, and it remained essentially unchanged over ～2.5 years of observations. We show that the mean interval between X-ray bursts from the source is several times shorter than assumed previously and that the burst profile itself depends on the flux during the burst. We analyze in detail the strong X-ray burst detected from this source on October 18, 1990, and construct the evolution curves of its luminosity and radiation temperature.  相似文献   

Seismic source representation in orthogonal functions     

D. W. Vasco 《Geophysical Journal International》1990,102(3):531-535

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