金州地区震旦系基本层序与沉积环境

金州地区广泛发育震旦纪地层,具分布连续、出露完整、沉积相标志明显的特点。本文运用现代沉积学和地层学理论,对区内震旦系岩石地层进行了基本层序研究与沉积环境分析。     

Pulsar Wind Nebulae in Egret Error Boxes

A remarkable number of pulsar wind nebulae (PWN) are coincident with EGRET γ-ray sources. X-ray and radio imaging studies of unidentified EGRET sources have resulted in the discovery of at least six new pulsar wind nebulae (PWN). Stationary PWN (SPWN) appear to be associated with steady EGRET sources with hard spectra, typical for γ-ray pulsars. Their toroidal morphologies can help determine the geometry of the pulsar which is useful for constraining models of pulsed γ-ray emission. Rapidly moving PWN (RPWN) with more cometary morphologies seem to be associated with variable EGRET sources in regions where the ambient medium is dense compared to what is typical for the ISM.     

锆石的裂变径迹年龄测定技术

六十年代初发展起来的核裂变径迹测定年龄技术,已在地质年代学、宇宙年代学和考古工作等领域得到了广泛应用。裂变径迹测定年龄技术,是应用各种天然矿物或材料中微量杂质铀的自发裂变碎片,在绝缘固体介质中产生的辐射损伤痕迹(即裂变径迹)测定年龄的方法。该法的优点之一是应用范围广,在火成岩、沉积岩和变质岩中常可找到合适的测定对象。     

Bukit Timah 花岗岩的动态拉伸力学特性实验研究

本文采用劈裂拉伸和三点弯曲法研究了Bukit Timah 花岗岩的动态拉伸力学特性.实验结果表明,当加载速率每增加一个量级,用两种方法得到的花岗岩抗拉强度增加10%.实验结果还表明,对于同种加载速率的花岗岩试样,由三点弯曲法得到的岩石抗拉强度约为劈裂拉伸法得到的2.5倍.与抗拉强度相比,实验得到的花岗岩弹性模量数据比较离散,变化幅度也不大.基于实验结果,本文还对岩石拉伸力学特性机理进行了初步分析.     

Deformation at Stromboli volcano (Italy) revealed by rock mechanics and structural geology

We approach the reconstruction of the recent structural evolution of Stromboli volcano (Italy) and the analysis of the interplay between tectonics, gravity and volcanic deformation. By tying together structural, lithostratigraphic and rock mechanics data, we establish that since 100 ka BP, the edifice has faulted and jointed mainly along NE-striking planes. Faults mostly dip to the NW with normal displacement. Taking also into account the presence of a NW-trending regional least principal stress and of tectonic earthquake hypocenters inside the cone, we suggest that this fracturing can be related to the transmission of tectonic forces from the basement to the cone. Dyking concentrated along a main NE-trending weakness zone (NEZ) across the volcano summit, resembling a volcanic rift, whose geometry is governed by the tectonic field. In the past 13 ka, Stromboli experienced a reorganisation of the strain field, which was linked with the development of four sector collapses affecting the NW flank, alternating with growth phases. The tectonic strain field interplayed with dyking and fracturing related to unbuttressing along the collapse shoulders. We propose that tectonics control the geometry of dykes inside the cone and that these, in turn, contribute to destabilise the cone flanks.     

河南西峡盆地上白垩统河流及湖泊沉积中的遗迹组构

河南西峡盆地上白垩统马家村组沉积厚度巨大,达1 960 m,由辫状河沉积、曲流河沉积和湖泊沉积组成。在河流与湖泊沉积中,发育丰富的遗迹化石,共6种类型,分别为Skolithos linearis、Cylindricumichnosp、Palaeophycus tubularis“J”形潜穴、垂直分枝潜穴和垂直螺旋潜穴。从形态分析,大多数为居住迹,按照遗迹化石产出岩层的岩性、扰动特征和残留遗迹等总体特征,将所发现的遗迹化石层划分为两类遗迹组构,即软底组构和僵底组构。前者主要发育在纹层状极细砂岩和粉砂岩中,潜穴密度大,属种单一,包括Skolithos组构和Palaeophycus组构;后者主要发育在厚层泥岩中,潜穴密度较大,类型稍多,包括由Cylindricum ichnosp、垂直分枝潜穴J形潜穴和垂直螺旋潜穴所组成的遗迹组构。与报道过的其他地区陆相遗迹化石的对比表明,随着时间的推移,河流沉积中的组构特征在白垩纪有明显变化,而浅湖沉积中的遗迹组构表明造迹生物的扰动能力显著加强。     

Soil contamination from urban and industrial activity: example of the mining district of Linares (southern Spain)

The Linares region (southern Spain) has been subjected to two important sources of pollution: the intensive mining works and the urban-industrial activity. To obtain a geochemical characterisation of the soil, 31 trace elements were analysed and 669 soil samples were collected. By means of clustering analysis, we identified groups of elements and grid squares in which relations could be established concerning soil lithology, urban and industrial activities and the degree of pollution impact; in addition, we were able to characterise the geochemical background of the study area. The multivariate study led us to identify four factors. Particularly important was factor 2, which represented the elements associated with mineral paragenesis (Cu, Pb, As, Co, Mn, Zn, Sn, Ba). This factor also contains elements related with an urban-industrial activity, such as Pb, Cu, Zn, As and Ba. Furthermore, we identified factor 4, associating Ni, V and Cr, and which is related to the use of fuels.     

The Mordor Alkaline Igneous Complex,Central Australia: PGE-enriched disseminated sulfide layers in cumulates from a lamprophyric magma

The Mordor Alkaline Igneous Complex (MAIC) is a composite intrusion comprising a body of syenite and a funnel-shaped layered mafic–ultramafic intrusion of lamprophyric parentage, the Mordor Mafic–Ultramafic Intrusion or MMUI. The MMUI is highly unusual among intrusions of lamprophyric or potassic parentage in containing primary magmatic platinum-group element (PGE)-enriched sulfides. The MMUI sequence consists largely of phlogopite-rich pyroxenitic cumulates, with an inward dipping conformable layer of olivine-bearing cumulates divisible into a number of cyclic units. Stratiform-disseminated sulfide accumulations are of two types: disseminated layers at the base of cyclic units, with relatively high PGE tenors; and patchy PGE-poor disseminations within magnetite-bearing upper parts of cyclic units. Sulfide-enriched layers at cycle bases contain anomalous platinum group element contents with grades up to 1.5 g/t Pt+Pd+Au over 1-m intervals, returning to background values of low parts per billion (ppb) on a meter scale. They correspond to reversals in normal fractionation trends and are interpreted as the result of new magma influxes into a continuously replenished magma chamber. Basal layers have decoupled Cu and PGE peaks reflecting increasing PGE tenors up-section, due to increasing R factors during the replenishment episode, or progressive mixing of between resident PGE-poor magma and more PGE-enriched replenishing magma. The presence of PGE enriched sulfides in cumulates from a lamprophyric magma implies that low-degree partial melts do not necessarily leave sulfides and PGEs in the mantle restite during partial melting. Electronic supplementary material  The online version of this article (doi:) contains supplementary material, which is available to authorized users.     

沉积钙质白云石带状面缺陷的择优取向

作者用透射电子显微镜研究了沉积钙质白云石中的带状面缺陷。在衍衬象中面缺陷呈现出特有的条纹衬度,并具有一定的择优取向,它们沿着｛018｝面排列。面缺陷也可分叉,分枝部分平等于｛2－／10｝面。根据白云石面缺陷的取向,本文提出了鞍状白云石宏观弯曲面和微观面缺陷的取向关系。     

<Superscript>226</Superscript>Ra, <Superscript>232</Superscript>Th and <Superscript>40</Superscript>K activities in soils of Cuihua Mountain National Geological Park,China

Gamma activity from the naturally occurring radionuclides namely, ²²⁶Ra, ²³²Th, the primordial radionuclide ⁴⁰K was measured in the soil of Cuihua Mountain National Geological Park, China using γ-ray spectrometry technique. The mean activity of ²²⁶Ra, ²³²Th and ⁴⁰K were found to be 27.2 ± 6.5, 43.9 ± 6.2 and 653.1 ± 127.6 Bq kg⁻¹, respectively. The concentrations of these radionuclides were compared with the typical world values and the average activities of Chinese soil. The radium equivalent activity, the air absorbed dose rate, the annual effective dose rate, and the external hazard index were evaluated and compared with the internationally approved values. All the soil samples have Ra_eq lower than the limit of 370 Bq kg⁻¹ and H _ex less than unity. The overall mean outdoor terrestrial gamma dose rate is 66.3 nGy h⁻¹ and the corresponding outdoor annual effective dose is 0.081 mSv.