Calculations of comet orbits from observations of 1982/83

From observations published in Smithsonian Astrophysical Observatory and MPC circulars corrected orbits of 30 comets have been calculated.     

阿尔泰成矿区大型、超大型矿床成矿规律综合信息研究

在综合信息矿产预测理论与方法指导下,通过地质、物探、化探资料综合信息解译工作,对阿尔泰成矿区大型、超大型矿床成矿规律进行了综合研究。绝大多数金、铜、铅（锌）矿床具有相同或相似的控矿因素,矿床我有共生或伴生的特点。它们处于：大地构造相对抬升的单元背景;不同大地构造单元相结合的部位;前寒武系变质岩系出露基底和隐伏基底及其边缘;泥盆纪火山岩或沉积岩组成的盆地边缘;中酸性继承性岩体及其接触带附近;重力场梯度带附近与重、磁资料推断相吻合的断裂构造及交汇处,以晚期重、磁构造为主;高、中、低温元素组合异常汇水盆地密集区。     

藏东玉龙超大型斑岩铜矿床成岩成矿系统时间跨度分析

藏东玉龙超大型斑岩铜矿床是目前西藏发现的最大斑岩铜矿床,含铜岩体主要由早期石英二长斑岩及晚期正长花岗斑岩组成。本文用LA-ICP-MS法测定早期石英二长斑岩及晚期正长花岗斑岩锆石U-Pb年龄及Ar-Ar法测定钾质蚀变带黑云母的Ar-Ar年龄,发现玉龙含矿斑岩体早期石英二长斑岩锆石LA-ICP-MS U-Pb年龄(41.3±0.3Ma, MSWD=0.92)与晚期正长花岗斑岩锆石LA-ICP-MS U-Pb年龄(41.3±0.2Ma, MSWD=1.24)基本相同,也和黑云母Ar-Ar坪年龄(41.7±0.8Ma)及等时线年龄(41.3±0.8Ma)在误差范围内一致。玉龙斑岩铜矿早期及晚期岩体锆石U-Pb年龄一致表明含矿岩体在地质上的早期及晚期主要是岩浆在较短时间内脉动侵入所致。玉龙含矿岩体锆石U-Pb年龄(封闭温度约800℃)、³⁹Ar-⁴⁰Ar 年龄(封闭温度约300℃)及前人获得的Re-Os年龄40.1±1.8Ma(封闭温度约500℃)在误差范围内基本一致,表明含矿岩体岩体快速冷却,玉龙超大型斑岩铜矿床成岩成矿系统时间跨度小于1Ma。     

两类埃达克岩的含矿性和成因:东南亚地区与东太平洋带对比

新生代埃达克岩是一种新型的火成岩(Sr/Y≥20),多产出于大洋岛弧、大陆边缘造山带(东南亚地区)和陆缘火山弧环境(东太平洋带),依据REE配分模式可将其划分为2种成因类型:大洋型(O型)和大陆型(C型)。埃达克岩分别广泛分布于东南亚地区的菲律宾群岛、苏拉威西、中加里曼丹、印度尼西亚几内亚岛、巴布亚新几内亚至所罗门群岛一带,及东太平洋带的北美洲、墨西哥、中美洲、南美洲的北部至南部。研究表明:不同成因类型的埃达克岩具有不同的含矿性,反映各自岩浆源区不同。C型埃达克岩(La/Yb12)是俯冲海洋板块部分熔融叠加增厚的地壳底部部分熔融MASH(熔融-混染-储存-均一化)和AFC(混染-分异-结晶)作用的产物,多半与世界级斑岩铜金矿床共生;O型埃达克岩(La/Yb≤12)则与平缓俯冲的海洋板片部分熔融作用有关,在东南亚地区主要与浅成热泉金矿有成因联系。     

复杂巨型滑坡形成机制三维离散元模拟分析

滑坡位于金沙江下游某拟建的大型水电站库区左岸,距坝址较近,总体积约为2 560万m3,属特大型滑坡,其稳定与否将直接威胁到大坝安全和水库正常运营。由于滑坡成因复杂,对其进行合理评价和科学预测尚有困难。为此,结合野外详细勘查资料的分析,对其形成机制进行了定性分析,认为主要以滑移-弯曲型为主,局部可能存在滑移-拉裂或蠕滑-拉裂变形。在此基础上,运用三维离散元数值模拟分析方法,再现了其变形破坏演化过程,进一步证实了其滑移-弯曲型变形破坏机制,很好地解释了主滑带低于现今河床、主滑体南侧边界比较模糊等原因,从而为其发展演化趋势、稳定性和危害性评价提供了有力依据。     

A New Giant Compsognathid Dinosaur with Long Filamentous Integuments from Lower Cretaceous of Northeastern China

1 Introduction Compsognathids are a small group of theropods commonly placed at the basal position within Coelurosauria (Sereno, 1999; Rauhut, 2003; Holtz and Osmólska, 2004; Norell and Xu, 2005). Recently new findings make the number of valid compsognathid genera increase rapidly. This group contains the relatively complete Compsoganthus (Ostrom, 1978; Bidar et al., 1972) and Juravenator (G?hlich and Chiappe, 2006) from the Upper Jurassic of West Europe, and Sinosauropteryx (Ji and J…     

Seismic sentinel? An analysis of captive giant panda behavior in response to the Lushan earthquake in China

It is widely believed that various animal species can sense and respond to the geophysical stimuli that precede earthquakes, especially electromagnetic fields, although supporting field evidence is mostly anecdotal. Here we report on the reactions of four female giant pandas under observation over the three days prior to the Lushan (30.1°N, 103.0°E) magnitude 7.0 earthquake that occurred in Sichuan province, China, on April 20, 2013. We observed no significant generalized behavioral anomalies indicative of them perceiving an impending earthquake. We also observed no startle behaviors in the 5 s prior to tremors commencing, indicating that these pandas either did not detect or did not respond to precursor P-waves. Our findings suggest that although giant pandas have evolved in, and continue to occupy exclusively, a seismically active range in central China, they do not appear to perceive pre-earthquake geophysical warning signs.     

汶川大地震震中喷发气、石的“爆烈式泥火山”场景——兼讨论地震的超临界水流体退相爆发成因

经多次现场核实,5．12汶川地震震中实为：有巨量喷发气、石的“爆烈式泥火山”伴大地震一巨量黑烟喷发和成千万m^3灰砂夹巨石千米抛射,同时引发烈度Ⅺ级的Ms8．0大地震。震中的此场景显然不能用传统构造运动成因自圆其说。汶川大地震只能是地内超临界水流体（简称SCW）退相爆发成因：地震带地下（10-20）km深处,汇聚了巨量SCW（H2O-CO2-空气-CH体系）流体,当其首先上窜到震中莲花心沟下方,减压至临界点（Pc=22．1Mpa）时,瞬间爆发退相,放出能量巨大和体积膨胀千倍的气体,爆发炸碎孕震库上方围岩,造成龙门山断裂带瞬间释放能量,形成大地震。     

Rb-Sr isotopic dating of sphalerite from the giant Huize Zn-Pb ore field,Yunnan Province,Southwestern China

The giant Huize Zn-Pb ore field in Yunnan Province, southwestern China, comprises the Qilinchang and Kuangshanchang deposits. The deposits are large in scale (more than 5 Mt of Zn and Pb) and high in grade (average grade of total Zn and Pb is 30%). Reported in this paper are the results of Rb-Sr isotopic dating of sphalerite from this ore field. Two precise ages (223.5±3.9 Ma and 226±6.4 Ma) have been obtained from two isochrons. These two ages are close to the reported ages of native copper mineralizations...     

Xenon isotope systematics, giant impacts, and mantle degassing on the early Earth

The relationships between the major terrestrial volatile reservoirs are explored by resolving the different components in the Xe isotope signatures displayed by Harding County and Caroline CO₂ well gases and mid-ocean ridge basalts (MORB). For the nonradiogenic isotopes, there is evidence for the presence of components enhanced in the light ^124–128Xe/¹³⁰Xe isotope ratios with respect to the terrestrial atmosphere. The observation of small but significant elevations of these ratios in the MORB and well gas reservoirs means that the nonradiogenic Xe in the atmosphere cannot be the primordial base composition in the mantle. The presence of solar-like components, for example U–Xe, solar wind Xe, or both, is required.For radiogenic Xe generated by decay of short-lived ¹²⁹I and ²⁴⁴Pu, the ¹²⁹Xe_rad/¹³⁶Xe₂₄₄ ratios are indistinguishable in MORB and the present atmosphere, but differ by approximately an order of magnitude between the MORB and well gas sources. Correspondence of these ratios in MORB and the atmosphere within the relatively small uncertainties found here significantly constrains possible mantle degassing scenarios. The widely held view that substantial early degassing of ¹²⁹Xe_rad and ¹³⁶Xe₂₄₄ from the MORB reservoir to the atmosphere occurred and then ended while ¹²⁹I was still alive is incompatible with equal ratios, and so is not a possible explanation for observed elevations of ¹²⁹Xe/¹³⁰Xe in MORB compared to the atmosphere. Detailed degassing chronologies constructed from the isotopic composition of MORB Xe are therefore questionable.If the present estimate for the uranium/iodine ratio in the bulk silicate Earth (BSE) is taken to apply to all interior volatile reservoirs, the differing ¹²⁹Xe_rad/¹³⁶Xe₂₄₄ ratios in MORB and the well gases point to two episodes of major mantle degassing, presumably driven by giant impacts, respectively  20–50 Ma and  95–100 Ma after solar system origin assuming current values for initial ¹²⁹I/¹²⁷I and ²⁴⁴Pu/²³⁸U. The earlier time range, for degassing of the well gas source, spans Hf–W calculations for the timing of a moon-forming impact. The second, later impact further outgassed the upper mantle and MORB source. A single event that degassed both the MORB and gas well reservoirs at the time of the moon-forming collision would be compatible with their distinct ¹²⁹Xe_rad/¹³⁶Xe₂₄₄ ratios only if the post-impact iodine abundance in the MORB reservoir was about an order of magnitude lower than current estimates. In either case, such late dates require large early losses of noble gases, so that initial inventories acquired throughout the Earth must have been substantially higher.The much larger ¹²⁹Xe_rad/¹³⁶Xe₂₄₄ ratio in the well gases compared to MORB requires that these two Xe components evolve from separate interior reservoirs that have been effectively isolated from each other for most of the age of the planet, but are now seen within the upper mantle. These reservoirs have maintained distinct Xe isotope signatures despite having similar Ne isotope compositions that reflect similar degassing histories. This suggests that the light noble gas and radiogenic Xe isotopes are decoupled, with separate long-term storage of the latter. However, without data on the extent of heterogeneities within the upper mantle, this conclusion cannot be easily reconciled with geophysical observations without significant re-evaluation of present noble gas models. Nevertheless the analytic evidence that two different values of ¹²⁹Xe_rad/¹³⁶Xe₂₄₄ exist in the Earth appears firm. If the uranium/iodine ratio is approximately uniform throughout the BSE, it follows that degassing events from separate reservoirs at different times are recorded in the currently available terrestrial Xe data.