Characteristics of magnetic and non-magnetic lag in the Cobar area, NSW

Geochemical patterns from two lag anomalies in the Cobar region of central New South Wales are described. The region is semi-arid, deeply weathered and some areas are covered by variable thicknesses of aeolian and alluvial transported overburden.Lag morphology and mineralogy are related to landform. In erosional landforms the surface is covered by lag, which is composed of coarse fragments derived locally from bedrock and displays varying degrees of ferruginization, together with a range of secondary pisoids. In depositional landforms the lag is less abundant and contains more pisoids. Deflation by sheetwash may lead to lag being partially buried by alluvium. In a large proportion of pisoid lag, hematite and goethite have been converted to maghemite, allowing ready separation into magnetic and non-magnetic fractions. The non-magnetic fraction is dominated by the lithic lag whereas the magnetic fraction is dominated by pisoid lag.The magnetic and non-magnetic components of the 2–11 mm lag fraction, milled to < 75 μm and subjected to HF-HNO₃-HClO₄ attack, give rise to distinct geochemical patterns at targets related to a variant of the Cobar style of Pb-Zn mineralization with variable silicification and to Zn mineralization in a swarm of quartz and carbonate veinlets. The patterns are influenced by metal source, lag type, surface chemical conditions and landtbrm. Differences in the correlation between metal contents in the magnetic and non-magnetic lag components, and between trace elements and Fe. indicate variable loss of Cu and Zn from the magnetic lag at some targets but retention of Pb. The presence of a readily cxtractable base metal component in the lag has implications for detecting anomalies in transported cover in the region.     

不同氮、磷浓度及配比对铜藻(Sargassum horneri)幼苗生长的影响

采用铜藻(Sargassum horneri)幼苗为实验对象,分别以Na NO3和Na H2PO4为氮源和磷源,研究了不同氮磷质量浓度及氮磷配比对铜藻幼苗生长的影响。进行了氮、磷单因子实验、双因子实验以及不同氮磷配比实验,实验时间为8d。结果表明:氮和磷对铜藻幼苗生长影响极显著(P0.01),且当氮、磷的质量浓度分别为8mg/L、0.4mg/L时,铜藻幼苗的特定生长率最大;交互作用影响不显著(P0.05),不同质量浓度的氮为主效应;不同氮磷质量浓度比影响极显著(P0.01),且当氮磷比为10:1时,铜藻幼苗的特定生长率最大。研究结果为铜藻幼苗培育过程中营养盐的合理调控提供了理论依据。     

pH值对单环刺螠呼吸排泄的影响

为研究pH值对单环刺螠(Urechis unicinctus)呼吸排泄的影响,采用静水密封法,研究了不同pH值(5、6、7、8、9)对体质量5.65±1.06g单环刺螠耗氧率、排氨率、能量代谢率、O/N值的影响.结果表明,pH值对单环刺螠耗氧率、排氨率、能量代谢率、O/N值均有显著影响(p0.05).单环刺螠耗氧率随pH值的升高而增大,pH值为8时达到最大值,之后随pH值的升高而减小.单环刺螠耗氧率与pH值之间的拟合方程为:OR=-2.977X2+55.188X-176.380,R2=0.937.单环刺螠排氨率的变化与耗氧率相似,在pH值为7时排氨率达到最大值;pH值为9时排氨率最小,与pH值为8的组差异不显著(p0.05).排氨率与pH值之间的拟合方程为:NR=-0.350X2+4.442X-6.822,R2=0.724.单环刺螠能量代谢率、O/N值均随pH值的升高呈先增大后减小的趋势,拟合方程分别为:M=-0.040X2+0.424X-0.044,R2=0.937;A=0.053X2+1.879X-7.470,R2=0.901.pH值为8的环境中,单环刺螠体内蛋白质代谢水平最低,有利于蛋白质的积累.研究表明,单环刺螠在一定pH值范围内可以通过调整生理代谢水平适应水体pH值,其适宜生活在弱碱性水中,生存最适pH值为8.     

Selenium and mercury concentrations in harbor seals (Phoca vitulina) from central California: Health implications in an urbanized estuary

We measured total selenium and total mercury concentrations ([TSe] and [THg]) in hair (n = 138) and blood (n = 73) of harbor seals (Phoca vitulina) from California to assess variation by geography and sex, and inferred feeding relationships based on carbon, nitrogen, and sulfur stable isotopes. Harbor seals from Hg-contaminated sites had significantly greater [THg], and lesser [TSe] and TSe:THg molar ratios than seals from a relatively uncontaminated site. Males had significantly greater [THg] than females at all locations. Sulfur stable isotope values explained approximately 25% of the variability in [THg], indicating increased Hg exposure for seals with a greater use of estuarine prey species. Decreased [TSe] in harbor seals from Hg-contaminated regions may indicate a relative Se deficiency to mitigate the toxic effects of Hg. Further investigation into the Se status and the potential negative impact of Hg on harbor seals from Hg-contaminated sites is warranted.     

2010年6月广西凌云-凤山交界3级震群应力水平分析

2010年6月28日至8月15日,在广西凌云与凤山交界持续发生了高密集、高集中、高频率的震群活动,共记录地震3 071次,其中ML2~2.9级地震41次,3级以上地震3次,最大为7月1日10时27分3.2级地震。对此次震群的空间分布范围、2级以上地震震源机制解P轴优势方向、b值特征、应力降等进行了分析研究。结果表明,此次震群震中集中,深度较浅,震源机制解P轴没有形成优势分布,序列参数b值较高,约为1.21,应力降主要分布在0.19~2.0 Mpa之间,认为广西凌云-凤山交界3级震群是属于低应力背景下的地震活动,不具有前兆震群和前震序列的性质。分析结果对正确了解此次震群的特征、正确判断地震趋势具有一定的帮助作用。     

Organic Geochemistry of the Early Jurassic Oil Shale from the Shuanghu Area in Northern Tibet and the Early Toarcian Oceanic Anoxic Event

This paper presents new geological and geochemical data from the Shuanghu area in northern Tibet, which recorded the Early Toarcian Oceanic Anoxic Event. The stratigraphic succession in the Shuanghu area consists mostly of grey to dark-colored alternating oil shales, marls and mudstones. Ammonite beds are found at the top of the Shuanghu oil shale section, which are principally of early Toarcian age, roughly within the Harplocearasfalciferrum Zone. Therefore,the oil shale strata at Shuanghu can be correlated with early Toarcian black shales distributing extensively in the European epicontinental seas that contain the records of an Oceanic Anoxic Event. Sedimentary organic matter of laminated shale anomalously rich in organic carbon across the Shuanghu area is characterized by high organic carbon contents, ranging from 1.8% to 26.1%. The carbon isotope curve displays the δ^13C values of the kerogen (δ^13Ckerogen) fluctuating from -26.22 to -23.53‰ PDB with a positive excursion close to 2.17‰, which, albeit significantly smaller, may also have been associated with other Early Toarcian Oceanic Anoxic Events (OAEs) in Europe. The organic atomic C/N ratios range between 6 and 43, and the curve of C/N ratios is consistent with that of the δ^13Ckerogen values. The biological assemblage,characterized by scarcity of benthic organisms and bloom of calcareous nannofossils (coccoliths), reveals high biological productivity in the surface water and an unfavorable environment for the benthic fauna in the bottom water during the Oceanic Anoxic Event. On the basis of organic geochemistry and characteristics of the biological assemblage, this study suggests that the carbon-isotope excursion is caused by the changes of sea level and productivity, and that the black shale deposition, especially oil shales, is related to the bloom and high productivity of coccoliths.     

河南箕山登封岩群变质中基性火山岩的地球化学及年代学研究

对登封岩群 TTG杂岩区内的斜长角闪质表壳岩包体以及绿岩区的变质中基性火山岩对比研究表明 ,其主元素、微量元素、稀土元素和同位素地球化学特征等指示该区的变质中基性火山岩同时同源 ,具有由拉斑玄武岩向钙碱性玄武岩演变的趋势.登封岩群上下部 2件 Sm Nd等时线年龄极为一致 ,可以合并为一条等时线 ,年龄为 (2 512± 19) Ma,ε Nd(t)=2.40± 0.16.综合分析认为 ,箕山地区的登封岩群稍晚于嵩山地区 ,是在新太古代末期一个非常短暂的时间内形成的 ,形成于类似现代岛弧的构造环境.     

极光亚暴期间的南极中山站地磁共轭点位置研究

通过对北极斯瓦尔巴特( Svalbard )岛Longyearbyen台站的 极光扫描光度计和地磁 观测数据在地磁亚暴膨胀相期间的对比分析,发现扫描光度计记录中的极光边缘的快速极向 运动和地磁数据x分量的陡峭负弯之间有着良好的对应关系,地磁数据可用来研究两极 高纬 地区极光亚暴的地磁共轭特征. 对南极中山站、挪威Troms Svalbard台链和东格陵兰岛 地 区共15个地磁台站在7个典型极光亚暴事件中的地磁数据进行对比分析后发现, 中山站的地 磁共轭点位置存在明显的漂移特征,漂移的范围在斯瓦尔巴特岛与东格陵兰岛之间,纬度值 与CGM模型值近似.     

盐度对近江牡蛎耗氧率、排氨率、O:N 和吸收率的影响

以半现场流水槽法研究了不同盐度(5、10、15、20、25、30、35)对近江牡蛎(Crassostrea hongkongensis)耗氧率、排氨率、O:N、吸收率的影响,并测定了盐度为20条件下牡蛎耗氧率和排氨率的周日变化.结果表明,近江牡蛎耗氧率、排氨率、O:N先随着盐度的升高而下降,在20左右降到最低,随着盐度继续上升,又升高;而近江牡蛎的吸收率先随着盐度的升高而升高,在20左右达到最高,然后随盐度升高而下降.根据数据得出耗氧率与盐度的拟合方程: y=0.0033x2-0.1161x+1.5523, R2=0.9018;排氨率与盐度:y=0.0001x2-0.0041x+0.0871, R2=0.9889;O:N与盐度:y=0.0016x3-0.0782x2+0.9051x+10.818, R2=0.955;吸收率与盐度: y=-0.0011x2+0.0399x+0.4393.R2=0.9453.一日内,8时、14时、19时、22时4个时间点,近江牡蛎耗氧率和排氨率变化较大,在14时最大,表明该时点其代谢活动最强.