云南东川因民铜矿金矿化特征及成因初探     

史文胜  曹新志  蔡志超  连永牢 《化工矿产地质》2008,30(1):23-27

因民铜矿发育两种金矿化类型:一是铜矿的伴生金;二是热液构造蚀变岩型。化探样品分析结果显示,金矿化主要赋存于金箔箐断层上、下盘的角砾状蚀变岩内,空间上受岩性和断裂构造的双重控制。邻区拖布卡金矿的成矿地质背景与本区相似,在成矿地质年代上作以类比推测,认为喜马拉雅期是主成矿期。另外通过对光片镜下和化探原生晕样聚类分析研究,发现构造蚀变岩型金矿化具明显的多期多阶段性及热液特征。  相似文献   

重液材料多钨酸钠在青海湖沉积物重力分离中的应用   总被引：1，自引：0，他引：1  

李善营  于炳松  Hailiang DONG  刘英超 《矿物岩石地球化学通报》2008,27(1):69-71

多钨酸钠是一种无毒、易配制、可循环使用、密度高的新型无机重液.本文利用多钨酸钠重液,用离心机重力分离的方法将青海湖沉积物分成低(≤1.9g/cm3)、中(1.2-2.8g/cm3)、高(≥2.8g/cm3)三个密度组分,平均回收率为96.5%.重力分离后的沉积物测试分析发现,有机质主要分布在富粘土矿物的中密度组,揭示了粘土矿物的表面吸附是青海湖底沉积物有机质的主要赋存形式.  相似文献   

Fluid–Sediment Interaction in a Marine Shallow-Water Hydrothermal System in the Wakamiko Submarine Crater, South Kyushu, Japan     

Miwako Nakaseama    Jun-Ichiro Ishibashi    Keita Ogawa    Hiroshi Hamasaki    Keiko Fujino  Toshiro Yamanaka 《Resource Geology》2008,58(3):289-300

The Wakamiko submarine crater is a small depression located in Kagoshima Bay, southwest Japan. Marine shallow‐water hydrothermal activity associated with fumarolic gas emissions at the crater sea floor (water depth 200 m) is considered to be related with magmatic activity of the Aira Caldera. During the NT05‐13 dive expedition conducted in August 2005 using remotely operated vehicle Hyper‐Dolphine (Japan Agency for Marine‐Earth Science and Technology), an active shimmering site was discovered (tentatively named the North site) at approximately 1 km from the previously known site (tentatively named the South site). Surface sediment (up to 30 cm) was cored from six localities including these active sites, and the alteration minerals and pore fluid chemistry were studied. The pore fluids of these sites showed a drastic change in chemical profile from that of seawater, even at 30 cm below the surface, which is attributed to mixing of the ascending hydrothermal component and seawater. The hydrothermal component of the North site is estimated to be derived from a hydrothermal aquifer at 230°C based on the hydrothermal end‐member composition. Occurrence of illite/smectite interstratified minerals in the North site sediment is attributed to in situ fluid–sediment interaction at a temperature around 150°C, which is in accordance with the pore fluid chemistry. In contrast, montmorillonite was identified as the dominant alteration mineral in the South site sediment. Together with the significant low potassium concentration of the hydrothermal end‐member, the abundant occurrence of low‐temperature alteration mineral suggests that the hydrothermal aquifer in the South site is not as high as 200°C. Moreover, the montmorillonite is likely to be unstable with the present pore fluid chemistry at the measured temperature (117°C). This disagreement implies unstable hydrothermal activity at the South site, in contrast to the equilibrium between the pore fluid and alteration minerals in the North site sediment. This difference may reflect the thermal and/or hydrological structure of the Wakamiko Crater hydrothermal system.  相似文献   

伊舒地堑方正断陷新安村组沉积微相研究   总被引：3，自引：1，他引：2  

陈宪保  柳成志  董秀超  李国一 《上海国土资源》2008,(3):41-44

依据岩心、地震、测井和录井资料,应用层序地层学和沉积学的原理和方法,查明了伊舒地堑方正断陷新安村组沉积微相特征.结果表明,方正断陷新安村组发育的沉积微相类型主要为分流河道、水下分流河道、河口坝、席状砂、滨浅湖砂质滩坝、泥质滩坝.在平面上沿北西部断裂向断陷中间依次过渡为扇三角洲平原、扇三角洲前缘、湖泊相,部分区域发育湖底扇;沿南东部断裂向断裂中间依次发育扇三角洲前缘和湖泊相.扇三角洲相在北部发育,湖泊相在南部和中部发育。  相似文献   

Environmental records of carbonaceous fly-ash particles from fossil-fuel combustion   总被引：3，自引：0，他引：3  

Maria Wik  Ingemar Renberg 《Journal of Paleolimnology》1996,15(3):193-206

Analysis of fly-ash particles in lake sediments has become increasingly important in studies of environmental pollution and lake acidification history. Most fly-ash studies have concerned black spheroidal carbonaceous particles (SCP)(>5 m) produced from oil and coal combustion. This review paper provides a summary of this technique and its application, and focusses on our investigations in Sweden between 1979 and 1993. It consists of five parts: i) preparation and analysis methods, ii) historical trends in atmospheric deposition, iii) geographical surveys of atmospheric deposition, iv) sediment dating, and v) studies of sedimentation processes in lakes. Methods for preparation and analyses of SCP have been developed and applied to investigations using sediment, soil and snow samples. Stratigraphic trends of SCP concentrations in lake-sediment cores reflect the consumption history of fossil fuels. A characteristic temporal SCP pattern, with a marked concentration increase beginning after the 1940's and a peak in the early 1970's, has been recognized in most Swedish lakes and elsewhere in Europe. A survey of SCP concentrations in surface sediments of >100 lakes covering Sweden demonstrated that polluted areas in southern Sweden had >100 times higher SCP concentrations than clean areas in the north. The spatial distribution of SCP over Sweden is similar to the deposition pattern of long-range transported airborne pollutants, such as excess sulphate monitored by network stations. SCP also accumulate in soils, and soil analyses can be used for determining the integrated historical deposition of SCP at the local or regional scale. Finally, SCP have been used for indirect dating of sediment cores and as a marker to assess sediment distribution patterns within lake basins.  相似文献   

The Taconite Inlet Lakes Project: a systems approach to paleoclimatic reconstruction     

R. S. Bradley  M. J. Retelle  S. D. Ludlam  D. R. Hardy  B. Zolitschka  S. F. Lamoureux  M. S. V. Douglas 《Journal of Paleolimnology》1996,16(2):97-110

A comprehensive study of meteorological, hydrological, limnological and sedimentological conditions in the watersheds of density-stratified (meromictic) lakes around Taconite Inlet, Northern Ellesmere Island, N.W.T., Canada was carried out from 1990–1992. Lakes C1 and C2 contain seawater trapped by isostatic uplift as the former embayments became isolated from the sea. These lakes, and Lake C3, contain varved sediments which provide an annually resolvable paleoclimatic record. By studing the major systems influencing sedimentation in one of these lakes (Lake C2) a better understanding of the climatic controls on varve formation, and hence on the paleoclimatic signal in the varved sediment record, was obtained. The varves of Lake C2 provide a proxy record of summer temperature for the region.This is the first in a series of papers published in this issue on the Taconite Inlet Lakes Project. These papers were collected by Dr R. S. Bradley.  相似文献   

Seismic signals in geothermal areas of active volcanism: a case study from ‘La Fossa’, Vulcano (Italy)     

Antonio Montalto 《Bulletin of Volcanology》1994,56(3):220-227

Since the last eruption (1888–1890) volcanism at Vulcano, Aeolian Archipelago, southern Tyrrhenian Sea, has taken the form of persistent fumarolic activity. The gas-vapour phases of the geothermal systems are mainly discharged within two restricted areas about 1 km apart from each other, in the northern part of the island. These areas are La Fossa crater, and the beach fumaroles of the Baia di Levante. Fluids released at the two main fumarolic fields display quite different chemical and temperature characteristics, implying different origins. The local seismicity essentially takes the form of discrete shocks of shallow origin (depth1 km) at La Fossa, usually with energy < 10¹³ ergs. They are thought to be related to the uprise of pressurized hot gases and vapours discharged at the crater fumaroles. The present investigation points to the existence of two principal categories of seismic events (called M-shocks and N-shocks). These are short events (normally < 10 s). M-type shocks are thought to be due to resonance vibrations within the interior of the volcano, probably driven by the excitation of shock-waves within cavities deeply affected by deposition and alteration of self-sealant hydrothermal minerals. N-type events display features that resemble those of volcano-tectonic earthquakes, but have no recognizable S-phases. Here they are tentatively attributed to microfracturing of rocks which have been extensively hydrothermally altered. Results of the present study permit a preliminary conceptual model of the local shallow seismic processes in the framework of geochemical modelling of fumarolic activity and geological inferences from geothermal drilling.  相似文献   

热液脉动与岩浆涌动控制机理浅论     

易顺化  李同林  李珍 《地质科技情报》1994,(1)

热液脉动与岩浆涌动的控制机理,是基础地质理论所涉及的两个重要议题。本文首先对当今流行的构造控制机理提出了质疑,其后借助＂间歇喷泉＂原理和＂吹气球＂机制,分别对热浪的脉动和岩浆的涌动进行了必要的探讨。  相似文献   

热液成矿作用的地质地球化学动力学——以胶东牟平-乳山金矿带为例   总被引：1，自引：0，他引：1       下载免费PDF全文

赵伦山  高大忠  李嘉 《地球科学》1994,3(3)

通过对胶东牟平—乳山热液脉状金,铅锌矿床成矿动力学控制规律的研究,说明了建立热液成矿反应体系的方法,并得出以下认识:（1）区域断裂构造活动,通过影响成矿反应体系的热力学性质和条件,控制元素的富集和分散。（2）热液成矿过程中容矿断裂活动可划分为两种作用方式:脆性破裂和韧—脆性张开,构成热液成矿的两种构造动力学环境。（3）热液成矿反应体系是一种开放的动态的热力学体系。断裂的脆性破裂阶段,使体系处于强烈的过饱和状态,矿质在远离平衡状态下快速结晶,加剧物质分异;在脆—韧性张开阶段,矿质在接近平衡态体系中缓慢晶出。（4）热液演化晚期,金在残余溶液中富集;当断裂再次发生构造脉动震颤时,早期形成的块状黄铁矿矿石碎裂,富金溶液充填其中,形成含裂隙金和晶隙金的富矿石。成矿体系热力学演化与构造动力学条件有利的匹配控制着富矿石的形成。  相似文献   

Palaeolimnological studies of the eutrophication of volcanic Lake Albano (Central Italy)     

Andrea Lami  Frank Niessen  Piero Guilizzoni  Julieta Masaferro  Claudio A. Belis 《Journal of Paleolimnology》1994,10(3):181-197

We use palaeolimnological techniques to reconstruct the eutrophication history of a volcanic lake (Lake Albano, central Italy) over the past three centuries. The presence of annual varves down to the bottom of the core (c. 1700 A.D.) indicated the lack of bioturbation and likely long-term meromixis. Sedimentation rates were estimated by varve counts (calcite/diatom couplets), indicating a mean rate of 0.15 cm yr^–1. The reconstruction of eutrophication was traced using past populations of algal and photosynthetic bacteria (through their fossil pigment), and geochemistry, as well as fossil remains of chironomids. Phaeophorbidea and the red carotenoid astaxanthin were used to detect past zooplankton development.The first sign of trophic change related to human activities is datedc. 1870 A.D. From that period onward a sharp increase of authigenic CaCO₃, nitrogen, N:P ratio, and dinoxanthin, a characteristic carotenoid of Chrysophyceae and Dinophyceae, is observed.Chironomid analyses showed the near absence of a deep water fauna throughout the core length. The populations of chironomid larvae are restricted to oxygenated littoral zones. In fact, the few fossil remains found are primarily of littoral origin, representing shallow water midges that were transported to profundal waters. The reduction of total chironomid in the uppermost layers of the core is to be related to human land uses.  相似文献