中印度洋海岭Edmond热液区块状硫化物中自然金的发现及其意义

位于中印度洋中速扩张洋脊的Edmond热液区块状硫化物矿石样品主要分为以黄铁矿-黄铜矿为主的富Fe块状硫化物、热水沉积成因的富含硅质块状矿石和以硬石膏为主的硫酸盐矿石等3种不同类型.通过扫描电镜观察和X射线光电子能谱分析,在硫酸盐矿石和富Fe块状硫化物中首次发现了自然金,最大粒径可达20 μm左右,主要呈不规则粒状或板状与硬石膏、闪锌矿等硫化物颗粒紧密共生,少量以次显微金形式沉淀在自形黄铁矿晶体表面.电子探针分析结果显示,晚期形成于中低温条件下的贫Fe闪锌矿中Au富集程度普遍较高(平均含量约为6700×10-6);Ag主要以类质同象形式赋存于与闪锌矿、黄铜矿伴生的硫盐矿物中(5.0％～6.7％ Ag),这表明贵金属元素的富集成矿作用与海底热液活动晚期的中低温成矿阶段有关.推断Au在该研究区以高温、酸性和氯度较高为特征的热液流体中主要呈AuCl2-或AuHS0形式迁移.而海水与热液流体混合、喷口流体发生相分离以及传导冷却作用,被认为是导致Au有效沉淀的重要控制因素.     

以文献计量看中亚成矿域研究发展态势

凭借巨量矿产资源供给能力和资源通道的特殊功能,中亚成矿域构成了我国资源安全体系的不可缺失的重要组成部分和举足轻重的一翼.科技文献能够反映科学研究的发展动态,利用Thomson DataAnlyzer(TDA)和UCINET对SCIE文献数据库中收录的1990—2010年间的中亚成矿域研究论文进行数据挖掘和分析.结果表明...     

新疆伊犁黄土磁化率增强机制差异性分析

本文对处于西风区的新疆伊犁昭苏黄土剖面进行了磁化率和粒度分析,初步探讨了伊犁黄土磁化率增强机制的差异性。研究表明,伊犁黄土虽然粘土含量较黄土高原黄土高,但细粒组分对磁化率的贡献非常有限,粗颗粒组分对磁化率贡献较大,说明磁性载体主要存于粗颗粒组分中。同时研究发现地形、沉积环境、源区矿物组分和气候等多种因素对磁化率产生不同程度的影响。伊犁黄土磁化率成因机制既具有阿拉斯加风速论模式的特点又叠加了黄土高原成壤作用的模式,即使在同一剖面的不同时段两种模式对磁化率增强的贡献也不同,伊犁黄土磁化率增强机制存在着时空差异性。     

Physical Properties, Morphology and Petrological Characteristics of Pumices from the Central Indian Ocean Basin

About 400 pumice clasts collected from the Central Indian Ocean Basin(CIOB)were studied for their morphology and were classified based on their shape and size.A majority of the samples range between<1 cm and 36 cm and in the Zinggs shape diagram plot in the equant and oblate fields.The Corey Shape Factor for most of the samples is close to 0.7,which is common for volcaniclastic material. The physical properties such as density,specific gravity,void ratio,porosity,moisture content and degree of saturation...     

滇中中晚元古代铜铁矿带成矿规律与找矿

滇中元古代铜铁矿带集中分佈东川、武定、易门、元江等多个大、中型矿床。中、晚元古代昆阳古陆间裂谷,在演化过程中发生火山喷流沉积、热水沉积、蒸发成岩、炭泥质吸附、热液改造和碎屑堆积等成矿作用,形成"四楼一梯"的裂谷成矿系列和矿床组合模式。深入分析"裂、火、构、盆、层、相"等成矿条件确定远景区,找矿方法应重视基础、分析差异、综合找矿。     

塔中台盆区原油正构烷烃摩尔浓度分布特征及意义

塔里木盆地塔中地区原油性质的多样性和复杂性十分罕见;分析表明,成熟作用和源岩相很可能是原油多样性的次要因素,主要影响因素可能与多期成藏或成藏后储层内的次生蚀变作用有关。本文对照正构烷烃摩尔浓度分布图版,辨别了塔中地区不同构造单元原油正构烷烃摩尔浓度的分布类型,分析了原油遭受次生蚀变作用的程度,以及蒸发分馏作用、气洗作用发生的原因及其对原油物性的影响。结果表明,由于运移通道以及与油气源的距离等因素,从塔中Ⅰ号断裂坡折带至中央断垒带,蒸发分馏作用和气洗作用发生的频率逐渐降低,但基态原油分布频率有增高的趋势。并且Ⅰ号断裂坡折带部分凝析油、高蜡油的形成主要与上述蒸发分馏、气洗、晶析等储层内的次生蚀变作用有关。     

Problems of Oxfordian and Kimmeridgian stratigraphy in northern Central Siberia (Nordvik Peninsula section)

The Oxfordian–Lower Hauterivian section of the Nordvik Peninsula (northern Central Siberia) is a reference for developing zonal scales for various fossil groups and improving the Boreal zonal standard. In the middle 1950s–late 1980s, it was studied extensively by geologists, stratigraphers, lithologists, and experts on various fossil groups. These studies yielded rich fossil and microfossil collections and a set of parallel zonal scales for various faunal groups. Recently, a new detailed ammonite zonation of the Oxfordian and Kimmeridgian units of this section has been proposed. These results contradict the previous biostratigraphic data on ammonites, foraminifers, and palynomorphs. In the present paper, all the biostratigraphic data on the Oxfordian and Kimmeridgian units of the Nordvik Peninsula (Cape Urdyuk-Khaya) and northern Central Siberia undergo a comprehensive analysis and comparison with those on the Boreal Realm. The ammonite-constrained stratigraphic position of the lower Upper Jurassic in the Cape Urdyuk-Khaya section is interpreted as Upper Oxfordian or Middle Oxfordian. In our view, this difference in the understanding is due to the misidentification of some Oxfordian ammonite forms. The zones based on other fossil groups (foraminifers, dinocysts) which were distinguished in the Upper Oxfordian and Kimmeridgian sections of the Nordvik Peninsula are well traceable circumarctically. Their stratigraphic position in various regions of the Northern Hemisphere is constrained by ammonites and bivalves. However, if we use the last alternative ammonite zonation of this section part, hardly explicable contradictions will appear in interregional foraminiferal and dinocyst correlations.     

Palaeoenvironmental interpretation of Late Pleistocene-Holocene morphosedimentary record in the Valsalada saline wetlands (Central Ebro Basin, NE Spain)

This work presents a palaeoenvironmental interpretation of the Upper Pleistocene-Holocene sedimentary sequence recorded in the Valsalada saline wetland system (Monegros, Central Ebro Basin). This morphosedimentary system developed on karstified, gypsiferous bedrock and was mainly fed by local saline groundwater. Based on geomorphological, sedimentological, palynological and radiocarbon data, three depositional units have been differentiated: 1) a lacustrine unit, which accumulated under cold/cool and humid environmental conditions at 41-40 kyr cal BP, 2) a fluvial unit that was deposited under arid climatic conditions with cold episodic periods from 14 to 3.5 kyr cal BP, and 3) an alluvial slope unit associated with arid climate with human influence during the Late Roman Period (1.5 kyr cal BP). The morphosedimentary evolution of the Valsalada system is strongly influenced by the geomorphic setting (small catchment with karstic depressions and low gradient slopes on gypsum), the hydrological availability (runoff and groundwater discharges) related to climate variability during the Late Pleistocene-Holocene, and the human activities developed in the area during historical times. The response of the Valsalada system displays a low sensitivity to short-term climatic changes but responds to major long-term climatic conditions, improving the regional paleoenvironmental picture of the Late Quaternary in NE Spain.     

Development and morphometry of drainage network in volcanic terrain, Central Anatolia, Turkey

This paper presents the results of morphotectonic and morphometric research carried out in order to determine the neotectonic development of the volcanic mountains and a drainage network in SW Cappadocia. The study area extends among the Aksaray, Ni?de, and Nev?ehir Provinces. The study area comprises Hasanda?, Melendiz, Keçiboyduran, Göllüda? Mountains and the adjacent parts of these volcanic mountains.Data collected exclusively from 1:25,000 digitised topographic maps and 10 m-resolution DEMs were used to define parameters related to the longitudinal profile of streams. The study area was divided into 10 volcanic units. Longitudinal profiles of 20 streams and stream orders were analysed to determine a regional tectonic differentiation pattern in these units. The streams in the study area drain into four different tectonic depressions. These depressions are Aksaray plain controlled by the Tuz Gölü fault (TGF), Çiftlik plain controlled by the Keçiboyduran–Melendiz fault (KMF), Misli plain controlled by the Derinkuyu fault (DF), and Bor plain controlled by the Ni?de Fault Zone (NFZ). An analysis of morphometric parameters shows that the development of a drainage network is associated with faults and rock resistance. Occurrence of morphometric parameters with different values in units reveals that the volcanic mountains were not uplifted in the same period and were subjected to different morphologic processes. High total order number in the south of Hasanda? (unit 3) and Melendiz Mountains (unit 7) indicate that the uplift ratio of the southern part is much greater than that of the northern part. Moreover, development of the drainage network in the south is in a more advanced phase than in the north. Indeed, the drainage network in the north is in the youngest erosional phase of all parts of the study area. The increased stream length-gradient indices (SL), and stream gradients and an analysis of headward erosion show that the streams displaying the longest and highest reach of the erosional phase are all in the southern part of Keçiboyduran and Melendiz Mountains. The longitudinal profile (Lp) of the present thalweg of the streams is irregular. The irregular Lp are associated with four different causes. These are geological variations in resistance, tectonics, and volcanic topography and downcutting in response to stream incision. The beginning of the fluvial incision in the northern part is younger than in the south.     

中亚地缘政治新格局及其对中国的战略影响

中亚作为一个相对独立的地缘政治单元,在区位、文化、社会等方面具有特殊性,在能源和资源方面具有显著的优势,在世界政治和国际关系中具有重要地位。自“9·11”事件所致的阿富汗战争之后,中亚地缘政治重新洗牌,多种国际政治行为体竞相介入中亚,形成复杂的地缘政治关系,中亚地缘政治格局发生新的变化,对中国产生新的和复杂的战略影响。