澳大利亚与元三古代海底喷气矿床伴生的电气石岩

在绿片岩、角闪岩和麻粒岩和变质岩层中，电气石岩和富电气石的沉积物与喷气矿化伴生，它们遭受了中等到强烈的变形，呈连续层状分布于褶皱构造附近，显示出诸如层理、递变层理、交错层理、层内滑动等沉积构造和拉裂构造。在高级变质作用区，它们显示变质结构，通常被再活化而成的石英－电气石脉所穿切。富电气石岩出现在由海底喷气而形成的Pb－Zn－Ag、Cu－Co、Cu－Bi、W、Sn、Au和稀土元素矿化的下部、内部及矿化之上，且在横向上与矿化同期的地层中。在一些地方，电气石岩没有上述矿化现象，也不与花岗质岩石相伴生。电气石的成分是黑电气石－镁电气石，虽反映了其全岩成分，但不能作为矿化的标志。虽然电气石是与花岗岩、交代岩、角砾岩简伴生的普通矿物，但本文描述的富电气石层为山硅电气石前身的变质作用产生的富硼硅质铁建造。它们是一种常见的喷气岩类型，并且常常出现在早－中元古代厚层的泥质变沉积岩和蒸发岩层序中。这就说明硼是由含硼的粘土的淋滤作用或由含硼酸盐的蒸发岩的淋滤作用产生的。     

Petrographic and SHRIMP Studies of Zircons fromthe Caledonian Xiongdian Eclogite, NorthwesternDabie Mountains

The Xiongdian eclogite occurring in the Sujiahe tectonic melange zone at Luoshan County, Henan Province, in the western Dabie Mountains, is typical high-pressure (HP)-ultrahigh-pressure (UHP) and medium-temperature eclogite. The occurrence, internal texture and surface characteristics of zircons in eclogite were studied rather systematically petrographically combined with the cathodoluminescence (CL) and scanning electron microscope (SEM) methods. Zircons are mainly hosted in garnet and other metamorphic minerals with sharp boundaries, have a multifaceted morphology and are homogeneous or exhibit a metamorphic growth texture in the interior, thus indicating that they are the product of metamorphism. SHRIMP analyses give zircon 206Pb/238U ages of 335 to 424 Ma and show a certain degree of radiogenic Pb loss; therefore it may be inferred that the age of 424? Ma represents the minimum age of a HP-UHP metamorphic age. From the above analyses coupled with previous Sm-Nd, 40Ar-39Ar, U-Pb and 207Pb/206Pb age d     

Impact of Aircraft NOx Emission on NOx and Ozone over China

A three-dimensional global chemistry transport model (OSLO CTM2) is used to investigate the impact of subsonic aircraft NOx emission on NOz and ozone over China in terms of a year 2000 scenario of subsonic aircraft NOx emission. The results show that subsonic aircraft NOx emission significantly affects northern China, which makes NOx at 250 hPa increase by about 50 pptv with the highest percentage of 60% in January, and leading to an ozone increase of 8 ppbv with 5% relative change in April. The NOx increase is mainly attributed to the transport process, but ozone increase is produced by the chemical process. The NOx increases by less than 10 pptv by virtue of subsonic aircraft NOx emission over China,and ozone changes less than 0.4 ppbv. When subsonic aircraft NOx emission over China is doubled, its influence is still relatively small.     

Amplitude—Phase Characteristics of the Annual Cycle of Surface Air Temperature in the Northern Hemisphere

The amplitude-phase characteristics(APC)of surface air temperature(SAT)annual cycle(AC)in the Northern Hemisphere are analyzed.From meteorological observations for the 20th century and meteorological reanalyses for its second half,it is found that over land negative correlation of SAT ACamplitude with annual mean SAT dominates.Nevertheless,some exceptions exist.The positive correlationbetween these two variables is found over the two desert regions:in northern Africa and in Central America.Areas of positive correlations are also found for the northern Pacific and for the tropical Indian and PacificOceans.Southward of the characteristic annual mean snow-ice boundary (SIB) position,the shape ofthe SAT AC becomes more sinusoidal under climate warming.In contrast,northward of it,this shapebecomes less sinusoidal.The latter iS also found for the above-mentioned two desert regions.In theFar East(southward of about 50°N),the SAT AC shifts as a whole:here its spring and autumn phasesoccur earlier if the annual     

Campanian Climatic Change: Isotopic Evidence from Far East, North America, North Atlantic and Western Europe

Paleoclimatic settings have been reconstructed for the Campanian using original oxygen-isotopic analyses of well-preserved molluskan and foraminifera shells from Russian Far East, Hokkaido, USA, Belgium and some DSDP holes (95, 98, 102, 390A, and 392A) in North Atlantic. Early Early Campanian climatic optimum has been recognized from data on high bottom shelf water paleotemperatures in middle latitudes of both the western circum-Pacific (to 24.2°C) and the eastern circum-Pacific (to 26.4°C) areas and high bottom shallow water paleotemperatures in high latitudes of the Koryak Upland (22.4–25.5°C), which agrees with the data on the Campanian Barykovskaya flora in high latitudes (Golovneva and Herman, 1998) and Jonker flora and its equivalents in middle latitudes. Judging from the data on comparatively high bottom shallow water paleotemperature values in high latitudes, South Alaska (19.4°C) and the Koryak Upland (22.4–25.5°C), we also expect Latest Campanian temperature maximum, which has not been confirmed, however, for low and middle latitudes by neither of isotopic nor paleobotanic data now. Main climatic tendency during the Campanian (with the exception of Latest Campanian) has been learned from isotopic composition of Campanian aragonitic ammonoid shells from the Hokkaido-South Sakhalin (Krilyon) marine basin. In contrary to Huber’s et al. (2002) assumption, we expect warm greenhouse conditions during the most part of the Campanian.     

Ecological quality assessment of small estuaries from the Portuguese coast based on benthic macroinvertebrate assemblages indices

Benthic macroinvertebrates communities are the most consistently emphasized biotic component of aquatic ecosystems and are one of the biological indicators required for assessment by the European Water Framework Directive. In this context, several indices based on these communities have been developed in order to assess ecological quality of estuarine systems. In the present work we used AMBI, M-AMBI, BENTIX and BAT to distinguish ecological status of five small estuarine systems of the Portuguese south and southwest coasts. Although indices outputs did not differ between systems and sampling seasons, results indicated that the metrics in which these indices are based could differentiate community structures as a result of two main gradients that force these communities: the natural variability, and the anthropogenic impact.     

Response of single benthic metrics and multi-metric methods to anthropogenic pressure gradients, in five distinct European coastal and transitional ecosystems

In recent times many benthic indices have been proposed to assess the ecological quality of marine waters worldwide. In this study we compared single metrics and multi-metric methods to assess coastal and transitional benthic status along human pressure gradients in five distinct environments across Europe: Varna bay and lake (Bulgaria), Lesina lagoon (Italy), Mondego estuary (Portugal), Basque coast (Spain) and Oslofjord (Norway). Hence, 13 single metrics (abundance, number of taxa, and several diversity and sensitivity indices) and eight of the most common indices used within the European Water Framework Directive (WFD) for benthic assessment were selected: index of size spectra (ISS), Benthic assessment tool (BAT), Norwegian quality index (NQI), Multivariate AMBI (M-AMBI), Benthic quality index (BQI), (Benthic ecosystem quality index (BEQI), Benthic index based on taxonomic sufficiency (BITS), and infaunal quality index (IQI). Within each system, sampling sites were ordered in an increasing pressure gradient according to a preliminary classification based on professional judgement. The different indices are largely consistent in their response to pressure gradient, except in some particular cases (i.e. BITS, in all cases, or ISS when a low number of individuals is present). Inconsistencies between indicator responses were most pronounced in transitional waters (i.e. IQI, BEQI), highlighting the difficulties of the generic application of indicators to all marine, estuarine and lagoonal environments. However, some of the single (i.e. ecological groups approach, diversity, richness) and multi-metric methods (i.e. BAT, M-AMBI, NQI) were able to detect such gradients both in transitional and coastal environments, being these multi-metric methods more consistent in the detection than single indices. This study highlights the importance of survey design and good reference conditions for some indicators. The agreement observed between different methodologies and their ability to detect quality trends across distinct environments constitutes a promising result for the implementation of the WFD’s monitoring plans. Moreover, these results have management implications, regarding the dangers of misclassification, uncertainty in the assessment, use of conflicting indices, and testing and validation of indices.     

北美五大湖区晚更新世劳伦泰德冰盖演化年代学综述及石英光释光测年的初步尝试

北美五大湖区的安大略湖北岸Don Valley Brickyard、Scarborough Bluffs、Bowmanville Bluffs剖面共同构成了北美东北部最长也是最厚的陆地第四纪沉积记录, 较完整地记录了晚更新世劳伦泰德冰盖(the Laurentide Ice Sheet)的演化. 晚更新世劳伦泰德冰盖演化的重建有赖于这些经典剖面中重要沉积地层单元的准确年代学控制. 传统的地层年代学主要是依靠少量¹⁴C年代, 将主要的混杂堆积单元(diamicton)解释为气候变冷环境下的冰川扩张, 并与指示全球冰量变化的深海氧同位素曲线一一比对建立起来的. 这样建立起来的年代学存在很大的不确定性. 20世纪80-90年代的少量热释光年代也不相吻合, 最近的13个长石红外释光定年则只集中于Bowmanville Bluffs的一个分层, 并未建立整个剖面的地层年代学, 使这些经典沉积剖面的年代学一直没有得到系统的建立. 应用石英光释光SAR-SGC法测试了Bowmanville Bluffs剖面Glaciofluvial Sand单元的2个冰水沉积样品, 年代结果分别为(41.6±3.8) ka、(48.1±4.4) ka, 分析表明这一年代结果偏老, 石英颗粒可能晒褪不完全. 由于大测片无法识别晒褪不完全的颗粒, 因此, 测试更多的剖面序列的光释光年代并尝试采用粗颗粒小测片或单颗粒技术解决样品颗粒晒褪不完全的问题将是必要的.     

西澳大利亚伊尔冈地块东部金矿田省太古宙地壳的演化

对西澳大利亚东部金矿田省太古宙花岗岩—绿岩地壳发展的几个不同模式作了系统的阐述。由于缺少以下几个方面资料,引起了许多争论: 1)绿岩和花岗岩的连续出露。 2)具有充分的区域的综合性多学科研究。 3)在对岩套研究中,用几种同位素方法进行补充的地质年代和岩石成因方面的研究。 4)标准地区的详细地球物理资料。     

同步轨道相对论电子通量长期倒空事件的统计研究

地球辐射带中有"杀手"电子之称的相对论电子通量增强和损失过程一直是空间物理学和空间天气学研究的热点.本文通过对2000—2016年间,地球同步轨道相对论电子通量降低至背景通量水平并持续时间长达3天以上这一特殊现象进行了相关统计研究.从事件的时间分布角度,本文研究了约1.5个太阳活动周内共62例事件随太阳活动水平高低的分布情况,结果表明:在太阳活动周下降期有较少的事件发生,而在峰年、谷年这类事件的发生率与太阳活动水平的高低并没有直接联系.随后,我们对这62例事件在开始、持续、结束三个阶段分别做了一些相关参数的统计,探讨相对论电子通量长期倒空事件的客观规律和产生机制.研究结果表明:事件发生前,太阳风动压、密度的显著增加引起磁层顶向内收缩,等离子体层顶一直维持在高L区域,IMF B_z分量南向和磁暴过程使相对论电子通量通过绝热和非绝热等物理损失机制降至背景通量水平.当这些相对论电子达到背景通量水平后,较弱的太阳风条件和地磁活动水平不足以提供充分的可以使相对论电子通量增长的源;虽然有些相对论电子通量长期倒空事件期间存在中、小磁暴过程,但这些强度较弱的磁暴很可能不会显著地影响...