Evidence for the Retrograde Accretion onto Supermassive Black Holestwo

Recently, Sloan Digital Sky Survey successfully carried out the reverberation mapping of a sky area, aiming to test the R ? L relation that has been already widely used. Here, R is the responsivity-weighted radius of the broad line region, and L is the optical luminosity at 5100 Å. Two results have been obtained from the data in the first year: (1) The time lags of AGNs (Active Galactic Nuclei) with a high accretion rate are much shorter than that estimated from the R ? L relation, which confirmed the results of reverberation mapping observations made by the Lijiang 2.4 meter telescope. (2) Some AGNs with a lower accretion rate also have very short time lags. The shortening of the time lags of the AGNs with a low accretion rate is caused by the retrograde accretion of black holes. This result has verified from observations the theoretical prediction made by Wang et al. (2014). The discovery of the black holes with a retrograde accretion has important significance, it indicates that the cosmological evolution of the black holes in quasars is implemented via the inherently random accretion.     

麻粒岩的形成及其对大陆地壳演化的贡献

麻粒岩是地球中最重要的岩石类型之一，它的形成主要受地热条件的控制。麻粒岩的形成可以与大陆碰撞、大陆拉张以及大陆弧模式相联系。麻粒岩在某种程度上，还是下地壳的同义词。通过麻粒岩地体地及火山岩中麻粒岩捕虏体的研究，使人们对地球深部的物质组成和结构有了直接的了解。麻粒岩在陆壳的形成和演化中具有举足轻重的地位。陆核说、陆壳垂直增生或横向增生说，都以麻粒岩作为重要的岩石学依据。     

西秦岭楔的构造属性及其增生造山过程

西秦岭楔是叠置于早古生代造山作用基础上形成的并插入祁连和昆仑早古生代造山带内部的楔形地质体,以大面积出露三叠系并发育多条蛇绿混杂岩带、大型韧性剪切带、中生代火山-岩浆作用和斑岩-矽卡岩型矿床为典型特征,具有增生造山作用的典型特征。这些蛇绿混杂岩带和岛弧钙碱性火山-岩浆岩的形成时代均具有向南逐渐变年轻的空间演化特征,显示了特提斯洋演化过程中海沟具有向南撤退的基本特征。砂岩碎屑组成以及源区特征研究结果表明,西秦岭楔三叠系形成于活动大陆边缘,其碎屑沉积物来自于古特提斯洋北侧的增生杂岩及岛弧。丰富的岛弧钙碱性火山-岩浆岩和沉积组合以及赋存的斑岩-矽卡岩型矿床,均与东昆仑及南秦岭相一致,呈现出相似的岩石组合类型以及岩石地球化学和同位素地球化学特征。这些事实表明,三叠纪时期,东昆仑、西秦岭以及祁连造山带是一个有机整体,自西向东存在一条三叠纪增生岩浆弧。锆石Hf同位素及岩石地球化学成分结果则表明,该增生岩浆弧部分岩浆来自于俯冲增生杂岩的部分熔融。     

古太平洋板块俯冲-增生时限：饶河增生杂岩的地球化学和年代学制约

饶河杂岩作为那丹哈达增生杂岩的主体,是古太平洋板块西向俯冲的直接证据。饶河增生杂岩组成与增生过程的研究对限定古太平洋板块向欧亚大陆的俯冲与增生过程具有重要的指示意义。本文在野外地质调查和饶河大岱地区大比例尺填图基础上,明确了饶河杂岩主要由枕状玄武岩、辉长岩以及大洋板块沉积地层(OPS)组成,这些岩石均呈构造透镜体状分布在海沟沉积物中,并被中生代花岗质岩脉所穿切,因此为限定饶河增生杂岩的组成、增生和就位时代提供了关键制约。地球化学数据表明玄武岩具有洋岛玄武岩(OIB)的地球化学属性。LA-ICPMS锆石测试结果表明该地区玄武岩和辉长岩的形成时代分别为166±2Ma和214±5Ma,限定了饶河杂岩中镁铁质-超镁铁质岩石的形成时代为晚三叠世至中侏罗世。结合该区粉砂质泥岩和砂岩的沉积时代下限分别为167±3Ma和133±4Ma,表明饶河杂岩的增生时代为167～133Ma,此外样品的碎屑年龄信息表明基质的物源为邻近的佳木斯地块和中亚造山带东段,其中前寒武的碎屑年龄在中国东北的多个陆块均有出现,可能源于早前存在的前寒武纪基底。本文测得侵入饶河杂岩的2个二长花岗岩形成年龄分别为126±1Ma和105±2Ma,表明饶河杂岩中的花岗岩脉主要形成于两个阶段,其中较老的花岗岩侵入体进一步限定了饶河杂岩的最终就位时代为133Ma至126Ma,表明古太平洋板块在中侏罗世至早白垩世存在西向俯冲-增生作用,为古太平洋板块的构造演化提供了重要的制约。     

Dynamical properties of a centrifugally driven outflow from a disc near a black hole

The inclination of the field lines at the surface of the disc plays a crucial role on the nature of the magnetically driven flows. For the non-relativistic case, a centrifugally driven outflow of matter from the disc is possible, if the poloidal component of the magnetic field makes an angle of less than a critical 60° with the disc surface (Blandford and Payne 1982). We investigate the dynamical properties of the magnetically driven flows from the disc near a non-rotating black hole and find that the critical angle becomes larger than 60° when the flows start from the region near the black hole.     

修正的粘滞律及有磁吸积盘的稳定性研究

本文采用修正的粘滞定律及磁流体力学研究了薄吸积盘内区及外区的稳定性问题。运用微扰方法导出了色散方程，分析了四种情况下吸积盘的不稳定性，结果表明：在同时考虑磁场和修正的粘滞律时，吸积盘中存在着三种振荡模式，其中粘滞模式总是稳定的，磁声速模式（包括向里、向外传播两种模式）通常是不稳定的。这些结果为解释ＢＬ Ｌａｃ天体、Ｓｅｙｆｅｒｔ星系、类星体等活动星系核的光变现象提供了理论依据。     

Transition from frontal accretion to underplating in a part of the Nankai Trough Accretionary Complex off Shikoku (SW Japan) and extensional features on the lower trench slope

Migrated multichannel seismic reflection profiles and bathymetry from a 200 × 120 km area of the Nankai Trough inner slope reveal three physiographic-tectonic domains on the lowermost slope. Linear ridges demarking laterally-continuous hangingwall anticlines above ramps in a relatively simple imbricate stack of trench turbidites characterize the western domain. An imbricate fan underlies a relatively flat structural terrace in the east. Between these two domains lies a compound knoll (Minami Muroto Knoll) some 40 km long, opposite which the thrust front pushes some 10 km further seaward than is the case in the domains to east and west. In the western ‘linear-ridge’ domain previous DSDP drilling penetrated turbiditic trench fill uplifted in the lowermost thrust-fold terrace above a decollement within the underthrusting Shikoku Basin (oceanic plate) sequence. The Shikoku Basin sequence in the western domain is divided into an upper, poorly reflective, hemipelagic claystone unit and a lower, strongly reflective, unit comprising Pliocene turbidites. The lower unit is traceable intact up to c.20 km landward below the lower trench slope and in the better resolved profiles the decollement lies along the base of the claystone unit. A similar decollement within the Shikoku Basin sequence in the eastern domain is traceable up to c.22 km landward. A critical seismic record crossing the western part of Minami-Muroto Knoll shows that the decollement is traceable only 8 km landward to a point, under the steep slope at the front of the knoll, landward of which the subducting Shikoku basin sequence is apparently thickened by as much as twice. This thickening, occuring as it does immediately along-strike from a simple imbricate fan to the east of the knoll and a relatively simple imbricate stack to the west (both evidently involving no strata from the lower Shikoku Basin unit) we ascribe to underplating by formation of duplexes of Shikoku Basin strata. Strike-parallel extension, akin to that postulated for high structural levels in certain thrust belts, is caused by uplift of the knoll as a result either of the underplating, or segmentation of the subducting oceanic crust, or both: a normal fault throws to the west off the west flank of the knoll. It bounds a transverse, trough-like, slope-basin with at least 900 m of fill. Upslope from the knoll broadly slope-parallel normal faults cut, and pond, recent slope sediments. The most impressive is a listric growth fault which dips trenchward. Alternative explanations for these involve extensional collapse of this part of the prism resulting from the subduction of a topographic high, or a zone of selective underplating below the trenchward portion of Minami Murato Knoll.     

窄吸积环动力学不稳定性的数值解

本文在细环近似和共转半么位移不为零的条件下，考虑吸积环中非轴对称动力学不稳定性的线性扰动过程，采用数值计算方法求得不稳定性的线性增长率和共转半径位移随波数的变化关系，发现线性增长率受共转半径不为零的影响较小，而共转半径位移项随波数的色散关系与线性Ｋｄｖ方程的色散关系相同，说明窄吸收环在动力学不稳定性数值模拟中出现的“行星状解”很可能是类似于Ｋｄｖ方程中的孤子解。     

津巴布韦克拉通构造变形特征分析

根据津巴布韦克拉通北部地区的构造变质特征及矿物测年数据,表明太古界地壳基底形成和演变分为两个阶段。早期约在26.7亿年,Shamva-Bindura绿岩带内发育平行层理的剪切带,在长英质片麻岩核组成的大型推覆体之间形成洋壳和火山岛弧物质的叠瓦状堆积,结果是炽热长英质和铁镁质岩层的堆积使得地壳的演变暂时达到均衡状态,岩层堆积厚度达35km。后期大约在26.0～26.2亿年炽热岩层的冷却收缩导致应变产生,沿垂直方向形成走向滑动断层带,为达到地热均衡,大面积的岩层发生熔蚀,并伴有花岗岩体底辟作用。岩层熔蚀和底辟作用产生二次临时变质作用和多种应变形态,也最终导致克拉通冷凝固化。     

Growth rates and ecology of coralline rhodoliths from the Ras Ghamila back reef lagoon,Red Sea

Rhodoliths are important marine carbonate producers that provide habitat for several marine organisms, and are threatened by ongoing global climate change. Meter‐sized sedimentary patches rich in living rhodoliths, interspersed among corals, were discovered in the back reef of Ras Ghamila lagoon, Southern Sinai, at less than 1 m water depth. In this shallow and relatively sheltered subtropical environment, rhodoliths were found to be monospecific or oligospecific, spheroidal, 3.5 to 9.4 cm in maximum diameter, with warty/lumpy or fruticose (protuberance degree IV) growth forms, and corresponded to the unattached branches or praline type. They grew in bright light under seasonal, moderate, wind‐driven water motion. The dominant rhodolith‐forming species recorded were: Lithophyllum kotschyanum, Porolithon onkodes, Hydrolithon sp. and three species of Neogoniolithon: Neogoniolithon fosliei, Neogoniolithon brassica‐florida, and an undescribed species noted in the text as Neogoniolithon sp. A total of 38 Alizarin‐stained rhodoliths was released in the field and collected after 1 year. They showed different banding patterns (alternating long and short cells) that revealed seasonal growth, with the lowest rates occurring in winter for all species, and an additional summer growth slackening in Neogoniolithon fosliei. Lithophyllum kotschyanum presented evidence of occasional growth cessation, possibly due to temporary burial. The observed annual growth rate of rhodoliths was unrelated to their size. The mean accretion rates were 1.08 mm · year^?1 in L. kotschyanum, 0.75 mm · year^?1 in P. onkodes, 0.49 mm · year^?1 in Hydrolithon sp., 0.85 mm mm · year^?1 in N. fosliei, 0.63 mm · year^?1 in N. brassica‐florida and 0.57 mm · year^?1 in Neogoniolithon sp. The annual mean marginal elongation rate for these taxa was respectively 8.74, 13.92, 3.59, 9.40 and 9.25 mm · year^?1, with the exception of Neogoniolithon sp., for which this parameter was not recorded. Maximum marginal elongation occurred in P. onkodes pointing out its greater ability as a space competitor in comparison with the other rhodolith species. The highest accretion rate and common presence of L. kotschyanum indicate its importance as carbonate producer in tropical reef.