Muglad盆地凯康坳陷生长断层活动定量分析及对油气成藏的控制

应用断层古滑距、滑动速率法研究苏丹Muglad盆地凯康坳陷生长断层活动,定量表征早白垩世、晚白垩世、古近纪-新近纪三幕构造旋回断陷期断层生长及活动强度的差异性。结果表明控凹断层为多期、多段式生长连锁模式;控构造带断层为初期生长连锁,后期简单生长模式;控圈闭断层表现为简单生长模式。早白垩世断陷期控凹断层分段生长影响烃源岩分布,断拗构造旋回造成砂泥岩沉积显著分异,形成下、中、上部多套储盖组合。油气的聚集层位及分布规律受圈闭类型、断层在Darfur群油气大规模运移期活动强度、Nayil组-Tendi组破坏期活动强度3方面因素控制,构造转换带横向背斜以及地垒型、反向断块型等古构造可形成早期残留油气藏或浅层次生油气藏,顺向断块不利于成藏。Darfur群与Nayil组-Tendi组滑移速率之比可以代表早期油气聚集与后期油藏破坏能力的相对大小,与单条断层伴生构造圈闭的油气纵向层位聚集状态有对应关系。凯康槽东侧为高产油气聚集带,隆起带以下组合白垩系成藏为主,断阶带上、中、下组合均能成藏;凯康槽西侧斜坡带和断阶带成藏条件差,隆起带北部成藏条件一般,多层系成藏但产量不高,隆起带南部成藏条件好于北部但以下组合白垩系成藏为主;坳陷带内断层晚期活动强烈,可形成次生油气藏。     

Preliminary magnetic studies of lagoon and stream sediments from Chascomús Area (Argentina)—magnetic parameters as indicators of heavy metal pollution and some results of using an experimental method to separate magnetic phases

Magnetic properties of lagoon and stream sediments from Chascomús area (Buenos Aires Province) and the relevance of various magnetic parameters as giving pollution status are studied in the present work. This work is focussed on magnetic parameters, such as concentration-dependent (magnetic susceptibility, saturation anhysteric and isothermal remanent magnetisation) and feature-dependent parameters (S-ratio, coercivity of remanence, anhysteric susceptibility/magnetic susceptibility-ratio), as pollution indicators. Firstly and most importantly, different magnetic parameters and chemical measurements were correlated in order to investigate their goodness, obtaining the best results for feature-dependent magnetic parameters. Coercivity of remanence correlate very well with chemical variables, showing correlations at high level of significance up to 0.9094, and the anhysteric susceptibility/magnetic susceptibility-ratio also shows very good correlations (up to 0.8376). Some results and advantages of using a new experimental method in order to discriminate hard and soft magnetic phases are also shown. This method uses alternately backfield isothermal remanent magnetisation and alternating field demagnetisation. From the experimental separation, the presence of hard magnetic phases in some samples was confirmed.     

Ecotoxicological evaluation of polycyclic aromatic hydrocarbons using marine invertebrate embryo–larval bioassays

The toxicity of polycyclic aromatic hydrocarbons (PAHs) was determined using mussel, sea-urchin and ascidian embryo–larval bioassays. Fluorescent light exposure enhanced phenanthrene, fluoranthene, pyrene and hydroxypyrene toxicity in comparison with dark conditions, but not naphthalene and fluorene toxicity. The toxicity of PAHs was inversely related to their K_OW values following QSAR models derived for baseline toxicity of general narcotics, whereas the obtained regression using toxicity data from photoactivated PAHs significantly departed from the general narcosis model. Also, the mixture toxicity of five PAHs to the larval growth of the sea-urchin was compared with predictions derived from the concentration addition concept, indicating less than additive effects. Finally, we compared our toxicity data with worst-case environmental concentrations in order to provide a preliminary estimate of the risk to the marine environment. Naphthalene, fluorene and pyrene are not considered to pose a risk to sea-urchin, mussel or ascidian larvae, whilst phenanthrene and fluoranthene may pose a risk for mussel and sea-urchin. Moreover, a higher risk for those species is expected when we consider the photoactivation of the PAHs.     

大别地块东南缘变质P-T条件及锆石U-Pb年代学研究

大别山东南缘高压-超高压地块一直为研究的热点地区,人们普遍认同其是由2个具有不同变质级别的单元构成,并以此为基点探讨大别造山带的俯冲、折返机制.然而,由于工作程度所限,对于大别山腹地店前-寺前-罗溪地区一直缺乏详细的资料,对其确实的变质属性及年龄并不清晰,限制了人们对该地区客观的结构单元划分的准确理解.本次通过区域变质岩石学和年代学的研究,详实地分析了该地块的结构构成.研究显示,大别山东南缘高压-超高压地块由2个超高压单元和1高压单元构成,并呈岩石-构造岩片形式相互叠置,其变质P-T条件分别为:(1)单元-Ⅰ:-T=723±22℃和-P=3.90±0.43GPa(金刚石稳定域);(2)单元-Ⅱ:-T=630 ±45℃和P=3.10 ±0.23GPa(柯石英稳定域);(3)单元-Ⅲ:-T=545±24℃和-P=2.48±0.11GPa(石英稳定域).锆石U-Pb年龄表明这三个单元具有穿时性,形成于不同的时间段,自单元-Ⅰ、单元-Ⅱ至单元-Ⅲ,年龄分别为226.4±2.6Ma→230.1±3.5Ma→235.2±4.2Ma年龄(徐旭峰等,2013).在空间分布上自北向南,总体的峰期变质P-T条件逐渐降低,年龄则逐渐变老.但由于风化剥蚀作用,在马龙-石马一线的单元-Ⅰ以构造窗形式产出,致使P-T条件呈现跳跃性的变化.石永红等:大别地块东南缘变质P-T条件及锆石U-Pb年代学研究     

Tidal and annual variability of the population structure of Eurytemora affinis in the middle part of the Seine Estuary during 2005

Annual variability in abundance and population structure of the copepod Eurytemora affinis was studied in the maximum turbidity zone of the Seine Estuary in 2005. An Eulerian sampling strategy was applied monthly from March to July and from September to December. Chlorophyll a and suspended particulate matter (SPM) concentration, copepod abundance and stage distribution, and phytoplankton abundance were measured in sub-surface and near-bottom water during the ebb phase. Total E. affinis abundance was at a maximum in March and April (>200 × 10³ ind. m⁻³), and decreased from May to September (<25 × 10³ ind. m⁻³). This decrease corresponds to annual increases in temperature, salinity, chlorophyll a concentration and phytoplankton abundance, which was dominated by large diatoms, and decreases in SPM and river discharge. The phenology observed in 2005 was almost two months earlier compared to previous studies in the 1990s, when E. affinis reached maximum abundance in May and June. The low proportion of nauplii (<50%) in the population and high abundance of ovigerous females suggests that low recruitment is probably related to anomalously low temperatures in late winter (<5 °C). Whatever the horizontal position of the population in the estuary, adult and late copepodid stages are distributed in higher salinity than naupliar stages. Overall E. affinis population abundance was driven by parameters that characterize water masses at the tidal scale and by river discharge and chlorophyll a at the annual scale. By integrating the tidal effect, the high-frequency sampling protocol used appears to be optimal for investigating annual variability of planktonic communities in megatidal estuaries.     

温度、盐度对海湾扇贝(Argopecten irradians)南北亚种回交幼虫生长和存活的影响

开展了海湾扇贝南北亚种杂交子代同海湾扇贝北方亚种间回交、杂交子二代及北方亚种对照组等群体的基因型和温度、盐度等环境因素之间的互作研究。研究结果表明,杂种F2和回交组别相对纯种组别存在生长优势。温度和盐度均对不同基因型群体的生产和存活产生显著的影响,其中在逆境温度下杂种F2和回交组能够更加适应并表现出更高的生长优势,而在盐度中结果却并非如此,这表明基因型和环境之间的互作机制比较复杂。研究结果为继续在不同海区环境下开展海湾扇贝回交育种提供了积极的理论依据和实践参考。     

基于卡方分布函数的辐射带电子蝴蝶状投掷角分布的优化判别方法

受不同物理过程影响,辐射带电子呈现多种投掷角分布类型,其中蝴蝶状分布尤为引人关注,其特征为通量在90°投掷角附近有极小值、在较低投掷角处达到峰值.现有研究普遍通过对几个特定投掷角间的通量比值进行限定来识别蝴蝶状分布,然而,该方法所挑选的电子分布并不一定符合蝴蝶状分布特征,这为准确研究电子蝴蝶状分布的现象学规律及其背后物理机制带来了一定困难.针对该问题,本文建立了一个基于卡方分布函数的判别模型,通过比较电子观测通量剖面与模型模拟的理想蝴蝶状分布剖面的相似性来判别电子蝴蝶状分布.使用范艾伦卫星上REPT仪器提供的L-shell > 3空间区域内两组不同投掷角分辨率的电子通量数据对该判别方法进行验证,结果表明该方法能明显提升判别效果,分别使基于17个投掷角和36个投掷角的电子通量数据判别蝴蝶状分布的误判率下降12.6%和27.5%.本文的分析结果证实了提高投掷角精度有利于准确确定辐射带电子的投掷角分布类型,发展的模型方法也对深入开展地球与行星磁层中电子蝴蝶状分布的统计学研究具有重要价值.

     

Site response in Tecoman,Colima, Mexico—II. Determination of subsoil structure and comparison with observations

In a companion paper local transfer functions were estimated at Tecoman using earthquake and microtremor data. In this paper, the subsoil structure at this city is investigated using seismic refraction and cross-correlation of noise records as a case study. P- and S-wave refraction profiles were measured at five sites within the city. Standard analysis constrained only very shallow layers. The P-wave refraction deployment was also used to record ambient vibration. These data were processed using an extension of the SPAC (SPatial AutoCorrelation (Aki, 1957) [1]) method; cross-correlation is computed between station pairs and the results are inverted to obtain a phase velocity dispersion curve. Penetration depth was larger than that from the refraction experiments but the shear-wave velocity of the basement could not be determined. For this reason, additional microtremor measurements were made using broad band seismometers with a larger spacing between stations. The results allowed to constrain the shear-wave velocity of the basement. Site amplification computed for the final profiles compare well with observed ground motion amplification at Tecoman. The case of Tecoman illustrates that even a simple subsoil structure may require crossing data from different experiments to correctly constrain site effects.     

梅雨锋的典型结构、多样性和多尺度特征

利用自动站、FY-2E卫星、多普勒雷达及NCEP再分析资料等, 对2015年7月23日皖江地区一次最强梅雨锋大暴雨过程成因进行分析, 重点分析此次过程中短时强降水中尺度特征。结果表明:(1)此次过程是一次典型的梅雨锋对流性暴雨, 贝加尔湖宽广的高空槽及副高和大陆高压的稳定维持是引发大暴雨过程的大尺度背景条件。高空槽、西南涡、地面β中尺度气旋的维持和加强为大暴雨提供了强劲的动力和水汽条件。(2)此次暴雨过程低层辐合明显、高层辐散显著、中层上升运动强盛, 非常有利于低层中尺度涡旋的发生发展。(3)短时强降水发生于边界层辐合由弱变强且趋于最强的时段内, 超低空风速的显著增大对暴雨有着重要作用, 边界层的垂直风切变和700 hPa的干侵入增强了层结的不稳定性。强降水发生时低层锋生明显加强, 锋生函数最强中心的位置与大暴雨区基本一致。(4)短时强降水发生于α尺度对流云团团状中心和皖江西部特殊喇叭口地形处, 且位于地面β中尺度气旋右侧南风气流中。(5)强度弱、底部低、平均切变值小的中γ尺度气旋使低质心、移动缓慢的对流风暴更具组织性, 持续时间明显增加, 更易产生短时强降水。