西藏日喀则地区德村-昂仁蛇绿岩内基性岩的元素与Sr-Nd-Pb同位素地球化学及其揭示的特提斯地幔域特征

系统研究了西藏雅鲁藏布江蛇绿岩带中部日喀则地区德村、吉丁和昂仁蛇绿岩中基性岩石的元素与 Sr-Nd-Pb 同位素地球化学特征。这些基性岩石,包括玄武岩、辉长岩和辉绿岩,属于低钾拉斑玄武岩系列,球粒陨石标准化稀土元素分配模式为轻稀土元素亏损的 N-MORB 型,(La/Yh)_N=0.31～0.65(除样品 DC993为1.17)。在原始地幔标准化微量元素图上,亏损高度不相容元素,与 N-MORB 配分模式一致。相对于 Th,无 Nb、Ta的亏损,显示样品不是产于 SSZ 环境。经构造环境图解判别,样品落入了 N-MORB 区域内;这些元素成分特征表明样品具有洋中脊环境或成熟的弧后盆地环境属性。Sr、Nd 和 Pb同位素组成特征表明特提斯地幔源区以 DM(亏损地幔)为主,同时存在少量 EMⅡ(富集地幔类型Ⅱ)、Sr,Nd 和 Pb 同位素组成特征还表明特提斯地幔域具有印度洋 MORB 型的 Sr-Nd-Pb 同位素组成特征。本文的结果进一步支持 Zhang et al.(2005)的研究结果,现今印度洋不仅在地理位置上占据了曾经是特提斯洋的大部分,而且它的地幔域还继承了曾经特提斯的地幔域的地球化学特征。     

内蒙古温都尔庙和巴彦敖包-交其尔蛇绿岩的元素与同位素地球化学：对古亚洲洋东部地幔域特征的限制

内蒙古中部发育的三条蛇绿岩带是华北板块和西伯利亚板块之间的缝合带。本文系统研究了其中的温都尔庙和巴彦敖包-交其尔两个蛇绿岩带中变质玄武岩的元素和 Sr、Nd、Pb 同位素地球化学。苏右旗温都尔庙碱性玄武岩为轻稀土富集型;岩石具有板内和大陆裂谷区玄武岩的特征,可能代表了600Ma 左右,温都尔庙地区开始发育的新洋盆。采自苏左旗的巴彦敖包-交其尔玄武岩分为两类,一类呈现轻稀土富集型,呈洋岛玄武岩特征;另一类具有明显的 Nb、Ta 负异常,显示大洋岛弧玄武岩特征,洋岛玄武岩的存在表明古亚洲洋曾经发育洋盆,大洋岛弧玄武岩的存在表明古亚洲洋内部有大洋岩石圈之间的俯冲。将本文的古亚洲洋洋岛玄武岩与中国西南地区的特提斯洋岛玄武岩进行系统的元素和同位素地球化学特征对比表明,古亚洲洋的洋岛玄武岩显示高 U/Pb(HU)和北大西洋和太平洋省的特征,而特提斯洋岛玄武岩属于印度洋省。这些说明古亚洲洋地幔域与特提斯地幔域是两个独立的构造域,它们代表了长期演化的两个不同的地幔地球化学域。     

Whipple telescope observations of LS I +61 303: 2004–2006

In this paper we present the results of the past two years observations on the galactic microquasar LS I +61 303 with the Whipple 10 m gamma-ray telescope. The recent MAGIC detection of the source between 200 GeV and 4 TeV suggests that the source is periodic with very high energy (VHE) gamma-ray emission linked to its orbital cycle. The entire 50-hour data set obtained with Whipple from 2004 to 2006 was analyzed with no reliable detection resulting. The upper limits obtained in the 2005–2006 season covered several of the same epochs as the MAGIC Telescope detections, albeit with lower sensitivity. Upper limits are placed on emission during the orbital phases of 0→0.1 and 0.8→1, phases which are not included in the MAGIC data set.      

Conservation status of New Zealand marine invertebrates, 2009

A re-evaluation of the threat status of New Zealand's marine invertebrates was undertaken in 2009, following earlier review of New Zealand's Threat Classification System and subsequent refinement of the national criteria for classifying threat of extinction to New Zealand's flora and fauna. Sufficient information was available to enable 295 marine invertebrate taxa to be fully evaluated and assigned to a national threat category. The 10 taxa at most risk of extinction (‘nationally critical’) were the giant seep clam Calyptogena sp., the primitive acorn barnacle Chionelasmus crosnieri, O'Shea's vent barnacle Volcanolepas osheai, the stalked barnacle Ibla idiotica, the four-blotched umbrella octopus Cirroctopus hochbergi, the roughy umbrella octopus Opisthoteuthis chathamensis, the giant squid Idioteuthis cordiformis, the large-egged polychaete Boccardiella magniovata and two gravel maggots, Smeagol climoi and Smeagol manneringi. The key threatening processes identified for marine invertebrates were fishing and land-use associated impacts such as sedimentation. We identified no taxa that had improved in threat status as a result of past or ongoing conservation management action, nor any taxa that had worsened in threat status because of known changes in their distribution, abundance or rate of population decline. We evaluated a small fraction of New Zealand's marine invertebrate fauna for their threat status. Many taxa remain ‘data deficient’ or unlisted. In addition to the most threatened taxa, we recommend these taxa and their habitats as priorities for further survey and monitoring.     

Strategies for selection of small γ-ray showers using the Imaging Atmospheric Cherenkov Technique

Methods of selecting small candidate γ-ray events obtained using the Imaging Atmospheric Cherenkov Technique are presented. Three approaches are described: a variant of the standard ‘Supercuts’ analysis technique, a parameter weights approach, and a neural network approach. A cut on the parameter combination Length/Size is developed and shown to be effective at rejecting background due to muons. The techniques are applied to observations of Markarian 421 taken during 1995 and 1996 with the Whipple 10 m reflector. The efficiency and stability of the three approaches are compared, and the Supercuts variant is shown to be the most robust. A signal is detected in the energy range 170 GeV to 300 GeV at a significance level of 6.5 σ, in 7 hours of observation (the standard analysis gives 15.2 σ for E > 300 GeV). This represents the first significant detection of a source at an energy threshold below 200 GeV using the Whipple 10 m system.     

An example of fingerprint detection of greenhouse climate change

As an example of the technique of fingerprint detection of greenhouse climate change, a multivariate signal or fingerprint of the enhanced greenhouse effect is defined using the zonal mean atmospheric temperature change as a function of height and latitude between equilibrium climate model simulations with control and doubled CO₂ concentrations. This signal is compared with observed atmospheric temperature variations over the period 1963 to 1988 from radiosonde-based global analyses. There is a significant increase of this greenhouse signal in the observational data over this period.These results must be treated with caution. Upper air data are available for a short period only, possibly too short to be able to resolve any real greenhouse climate change. The greenhouse fingerprint used in this study may not be unique to the enhanced greenhouse effect and may be due to other forcing mechanisms. However, it is shown that the patterns of atmospheric temperature change associated with uniform global increases of sea surface temperature, with El NinoSouthern Oscillation events and with decreases of stratospheric ozone concentrations individually are different from the greenhouse fingerprint used here.     

Stereoscopic observations of gamma rays at the Whipple observatory

Observations of photons at E ≥ 550 GeV from the Crab Nebula are presented and used to assess the potential of multi-telescope systems for γ-ray astronomy.

The Whipple observatory 10 m and 8 m imaging atmospheric erenkov telescopes have been used to provide a stereoscopic view of air showers to make a more complete measurement of air shower parameters. Here we present a measurement of the spread in the arrival direction of primary γ-rays originating from a point source. The data show that the shower arrival direction can be reconstructed with an accuracy of σ = 0.°14.     

Search for shadowing of primary cosmic radiation by the moon at TeV energies

The antimatter research through the earth moon ion spectrometer (ARTEMIS) experiment is described in terms of searching for the moon's shadow in the primary cosmic radiation at TeV energies. Observations were made using the Whipple 10 m Imaging Atmospheric erenkov Telescope, in conjunction with a special optical filter to suppress unwanted moonlight. Monte Carlo simulations were used to predict that the magnitude of shadowing based on a pure proton beam would be 1% of the cosmic ray background. Observations and event classification are discussed, and results of a search for shadowing based on both protons and antiprotons are presented. Atmospheric fluctuations giving rise to non-statistical event rates constituted a limiting factor to the sensitivity of the shadow search as they rivaled or exceeded statistical errors. It is demonstrated that the experiment does not have sufficient sensitivity to moon shadowing which would allow a search for an antimatter component in the primary cosmic ray flux at the percent level. Possible future improvements of the technique are discussed.     

A Survey of Unidentified Egret Sources at TeV Energies

The Whipple Observatory 10 m γ-ray telescope has been used to survey the error boxes of 24 EGRET unidentified sources in an attempt to find counterparts at energies of 350 GeV and above. In no case is a statistically significant signal found in the EGRET error box which implies that, at least for this sample, the γ-ray spectra of these sources steepen between 100 MeV and 350 GeV.     

Application of singular value decomposition (SVD) in high energy γ-ray astronomy (E0 0.1 TeV)

Recent advances in TeV γ-ray astronomy have been made using imaging techniques which reject in excess of 99% of the cosmic ray background while simultaneously detecting more than 50% of the genuine γ-ray signal. Here we describe an advanced signal processing technique, Singular Value Decomposition (SVD) and discuss its successful application to the TeV γ-ray database obtained by the Whipple Collaboration