The tectonic and metallogenic framework of Myanmar: A Tethyan mineral system

Myanmar is perhaps one of the world's most prospective but least explored minerals jurisdictions, containing important known deposits of tin, tungsten, copper, gold, zinc, lead, nickel, silver, jade and gemstones. A scarcity of recent geological mapping available in published form, coupled with an unfavourable political climate, has resulted in the fact that, although characterized by several world-class deposits, the nation's mineral resource sector is underdeveloped. As well as representing a potential new search space for a range of commodities, many of Myanmar's known existing mineral deposits remain highly prospective. Myanmar lies at a crucial geologic juncture, immediately south of the Eastern Himalayan Syntaxis, however it remains geologically enigmatic. Its Mesozoic-Recent geological history is dominated by several orogenic events representing the closing of the Tethys Ocean. We present new zircon U-Pb age data related to several styles of mineralization within Myanmar. We outline a tectonic model for Myanmar from the Late Cretaceous onwards, and document nine major mineralization styles representing a range of commodities found within the country. We propose a metallogenetic model that places the genesis of many of these metallotects within the framework of the subduction and suturing of Neo-Tethys and the subsequent Himalayan Orogeny. Temporal overlap of favourable conditions for the formation of particular deposit types during orogenic progression permits the genesis of differing metallotects during the same orogenic event. We suggest the evolution of these favourable conditions and resulting genesis of much of Myanmar's mineral deposits, represents a single, evolving, mineral system: the subduction and suturing of Neo-Tethys.     

Areal value assessment of the mineral resources endowment of Israel

The achievements of the mineral industry of Israel and an overall reconnaissance of the natural resources endowment of the country have been evaluated by the areal value estimation method, using the COMOD software package. In broad terms, the evaluation relies on geological variables obtained from quantifying the geological map of a region and on cumulative past production records, which, when prorated per unit area, yield a series of unit regional values (u.r.v.)measurements for individual commodities, resource sectors, and total resources. The two groups of variables facilitate conducting comparisons with other well-developed and/or geologically similar regions from which the future potential of the region, with respect to both overall endowment and individual commodities, can be assessed. The model underlying this appraisal method assumes that all regions above a size of about 5,000 sq kms are equally valuable with respect to total endowment in natural resources, regardless of inherent geological characteristics. To date, several areal value estimation studies have been carried out for 11 different countries, encompassing a total of 111 politically-administratively defined regions. These studies provide an adequate information base for between-region comparisons. The individual states of the United States, constituting what can be regarded as well-developed regions, may serve as an expectation for all such comparisons. The distribution of the u.r.v. of total resources of the individual states is lognormal with a geometric mean of 54,954 1967 U.S. dollars per square kilometer. Based on the above assumption, this value can serve as a conservative estimate for the total output any region can be expected to produce. Thirty different mineral commodities are known to exist in Israel. Of these, 19 are economically exploited and the remaining 11 are at present uneconomical mineral occurrences. Past production records have been obtained and assembled for 14 of the exploited commodities. From these records, a number of statistics were computed to evaluate the development of the mineral industry of the country and its future potential. In absolute figures, the overall cumulative production has been rather small, amounting to only 1,679.8 million deflated 1967 U.S. dollars (equivalent to 2,082 million current U.S. dollars or 10,260 million current Israeli pounds). Only bromine, potash, and phosphate are of worldwide significance, amounting respectively to 10, 2.9, and 1 percent of the world production in 1977. Construction materials, with the longest production history, have been the most valuable, accounting for 53.6 percent of the total cumulative output. They are followed by nonmetals (34.7 percent),metals (8 percent)and fuels (3.7 percent).The value-ranking of individual commodities and their respective contribution to the total cumulative output is: cement, 35 percent; potash, 19 percent; stone, 15 percent; phosphate, 11 percent; copper, 8 percent; sand and gravel, 4 percent; bromine, 3 percent; petroleum, 2.5 percent; natural gas, 1 percent; periclase, 0.7 percent; salt, 0.4 percent; and glass sand, 0.2 percent. Total annual output for the period 1948–1977 exhibited a constant growth with no indication of approaching a plateau of diminishing returns. As new commodities became exploited, the share of constructional materials in the total output gradually declined from 100 percent in 1948 to 45 percent in 1977. The contribution of the mineral industry to the annual gross national product rose steadily from 0.55 percent in 1951 to 2.2 percent in 1964. Thereafter, it fluctuated around an average of about 1.8 percent. Total output and production of constructional materials correlate very highly with both gross national product (GNP)and population size. However, when only the annual changes in these variables are considered, the correlation coefficients are found to be insignificant. The u.r.v. of Israel (with an area of 20,700 sq kms and a population of 3,653,000)is 81,154 deflated 1967 U.S. dollars per sq km. It exceeds the expected value for well-developed regions. It can therefore be concluded that Israel is not exceptionally poor in natural resources, as is commonly felt. On the other hand, its high u.r.v. also implies (unfortunately)that the development potential of its mineral industry is rather limited. The u.r.v. estimates, which are based on area alone, can be refined to some degree by considering the geological characteristics of the investigated area. The geological composition of the country was quantified by point counting the geological map, using a grid network of 40.3 sq km cells. Each map unit was assigned to one of 65 standard time-petrographic units. This sampling density results in the recognition of 11 time-petrographic units (instead of 15, which are actually present).Based on linear statistical association between mineral resource diversity and geological diversity established for the states of the United States, Israel can be expected to possess 31 different commodities. Since only 19 have thus far been exploited, Israel can be expected to produce 12 additional commodities. The identity of these missing resources can be inferred by examining the inventory of commodities produced in other regions with a similar geological framework and by evaluating the potential of the 11 noneconomical mineral occurrences, which have already been discovered in the country. The geology of Israel was compared to 12 other regions; of these Egypt, Libya, Sudan, and Sinai were found to be most similar to Israel, each having 8 or 9 time-petrographic rock types in common with Israel, 7 of which are identical. Based on these comparisons and on additional information from other sources, it appears that the commodities that are more likely to be produced in the foreseeable future include manganese, feldspar, uranium (from phosphates),lignite, oil shale, and iron. The mineral industry of Israel accomplished quite significant achievements in the course of its modern history of only 35 years. These resulted from concerted national exploration and development efforts, which were supported by massive governmental capital investments. The areal value method of mineral resources appraisal is based on a cybernetic black box system model in which the degree of commitment derived from the socioeconomic infrastructure is viewed as the driving agent in converting the inherited geological characteristics of the region into economic marketable mineral commodities. The case history of Israel provides a strong substantiation for this generalized system model.     

Crustal structure across southern Mexico inferred from gravity data

We present a gravity model of the crustal structure in southern Mexico based on interpretation of a detailed marine gravity profile perpendicularly across the Middle America Trench offshore from Acapulco, and a regional gravity transect extending into continental Mexico across the Sierra Madre del Sur, the central sector of the Trans-Mexican Volcanic Belt, the Sierra Madre Oriental, the Coastal Plain, and into the Gulf of Mexico. The elastic thickness of the Cocos lithospheric plate was found to be 30 km. In agreement with a previous seismic refraction study, no major differences in crustal structure were observed on both sides of the O’Gorman Fracture Zone. The gravity high seaward of the trench is interpreted as due to the incipient flexure and crustal thinning. The gravity low at the axis of the trench is explained by the increase in water depth and the existence of low-density accreted or continental-derived sediments (2.25 and 2.40 g/cm³). A gravity high of 50 mGal extending about 100 km landward is interpreted as caused by local shoaling of the Moho. The crust attains a thickness of 42 km under the Trans-Mexican Volcanic Belt but thins beneath the Coastal Plain and the continental slope of the Gulf of Mexico. Gravity highs around the Sierra de Tamaulipas are interpreted in terms of relief of the lower–upper crustal interface, implying a shallow basement.     

Lateral variations of coda Q and attenuation of seismic waves in the Gulf of Suez, Egypt

Gulf of Suez consists mainly of three tectonic provinces that are separated by two accommodation zones. The southern edge of the gulf is bordered by N–S faults which mark the transition between the shallow water, Suez Basin and the deep northern Red Sea Basin. The sensitivity of coda Q measurements with respect to geological differences in the crust is demonstrated in three regions with a large variety of tectonic and geologic properties. The estimation of coda Q (Qc) is performed for 370 local earthquakes recorded at 12 digital seismic stations during the period from 2000 to 2007. The magnitudes of the earthquakes between 1.5 and ~4.5 have been used at central frequencies 1.5, 3, 6, 9, 12, 15, 18, and 24 Hz through three lapse time windows 10, 20, 30 s starting at once and twice the time of the primary S wave from the origin time. The time domain coda decay method of the single isotropic scattering model is employed to calculate frequency-dependent values of coda Q. The Qc values are frequency dependent in the range 1–25 Hz, and are approximated by a least squares fit to the power law [Qc(f) = Qo(f/fo)η]. The observed coda Q indicates that the area is seismically and tectonically active with high heterogeneities. The variation of the quality factor Qc has been estimated at different regions to observe the effect of different tectonic province. The average frequency-dependent estimated relations of Qc vary from 65f1.1 to 96f0.9 at 10 to 30 s window length, respectively. The decreasing value of the frequency parameter with increasing lapse time shows that the crust acquires homogeneity with depth. The variation of Qc with the variations in the geologic and tectonic properties of the crust was investigated. The frequency exponent η might be larger in active tectonic areas and smaller in more stable regions. In the northern region of the Gulf of Suez, the obtained value of η?=?0.8?±?0.011, which might indicate a low level of tectonic activity compared with η?=?1.1?±?0.005 and 1.3?±?0.009 for the central and southern regions of the gulf.     

河南省构造演化与矿床成矿系列

河南省大地构造单元涉及华北陆块、秦岭造山带和扬子陆块。前中侏罗世华北陆块区的大地构造单元划分在省内外基本上形成了共识,而有关秦岭造山带构造单元的划分存在较大分歧,许多岩石地层单位具有跨代性。根据大地构造演化特征和新发表的同位素年龄数据,将各大地构造单元划分为10个构造演化阶段,各阶段均形成了优势大地构造相和相应的矿产资源。在一定的大地构造演化阶段、一定的大地构造相分布一定的矿产或矿床组合,不同大地构造单元各个构造阶段的相系清晰反映了矿床的空间分布规律。根据矿床形成的地质构造环境、成矿作用等特征,将河南省众多矿床厘定出27个矿床成矿系列。文章基于大地构造演化进行矿床成矿系列的划分是一种新的探索。     

The role of regional lithogeochemistry in mineral exploration

Regional lithogeochemical surveys can be used to determine the geochemical characteristics of particular tectonic regions as well as mapping geochemistry in relation to geology and ore deposits at a larger scale. Regional lithogeochemistry is of particular value for assigning signatures to associations of igneous rocks which are related geochemically and geologically.The application of regional lithogeochemistry to mineral exploration is reviewed here with particular reference to the Mesozoic magmatic province of Mongolia. Geochemical data for granitoids are shown to have particular application to: (1) the classification and grouping of rocks of similar petrochemical and mineral compositions; (2) the compilation of tectonic and metallogenic maps; (3) the identification of metallogenic provinces and ore zones; and (4) predictive modelling to identify ore-bearing associations. Moreover, such data can be used to estimate the probable types and sizes of ore bodies associated with particular geochemical rock types. Regional lithogeochemistry thus forms an essential basis for prospecting for mineral deposits.     

Mineral resource assessment using the unit regional value concept

The resources produced in some specific region may be measured in terms of the amount of resource produced and its value: if these measures are cumulated over the period of production and prorated over the area of a region. say in km², they yield the unit regional weight (u.r.w.) and unit regional value (u.r.v.) of resources produced in the region. Frequency distributions of u.r.w. and u.r.v. may be constructed by measuring them on a number of regions; for the 50 states in the U.S.A. the logarithm of u.r.v. is normally distributed and hence different regions may be ranked on this scale using the mean and standard deviation intervals as calibration levels. The u.r.w. and u.r.v. of the 50 states in the U.S.A., may be used as a reference background for such comparisons. The average u.r.v. for all resources produced over the period 1905 to 1972 for the 48 coterminous states is 54.954 (1967) U.S. (S). Alaska, over the same period, possess a u.r.v. of 2738 (1967) U.S. (S) and so its u.r.v. is some 20 times less: this yeilds a conservative measure of the future potential for development of the mineral resources of Alaska. This unconditional estimate of the u.r.v. of Alaska is based solely on its area and one way of refining this estimate is to introduce geology as a conditioning variable. The geological composition of each state in the U.S.A. was point counted from available geological maps of the states and the proportions of different rock units were expressed in terms of 65 standardized time-petrographic units. The accumulated data for ail 50 states yields a diversity (or richness=s−1) of 51 rocktypes: the range in value for the individual states extends from an s−1=1 in Louisiana to s−1=25 in California. Alaska is about seventh among the states in geological diversity and groups with Arizona, Montana. Utah. Nevada, and Washington. However, the dominant rocktype in Alaska is the detrital high-rank graywacke and this characteristic eliminates all but Nevada as a geologically comparable state. New Zealand also possesses similar geological characteristics. The diversity of mineral resources produced in each region may also be standardized and measured in a similar manner as richness=s−1. It has been found that there is a linear association between mineral resource diversity (Y) and the variety of geological roccktypes (X): the degree of common association between these two variables isr ²=80%. This relationship may now be used as predictor equation and we can calculate the expected value for Alaska as s−1=45 against an observed mincral resource variety of s−1=27. Since Nevada (s−1=49) and New Zealand (s−1=36) both possess much higher resource diversity than Alaska it is likely that the extra resources produced in these two regions should be present in Alaska. This permits us to pinpoint, first. the mineral resource sectors, such as constructional materials. fuels. metals. precious metals, and nonmetals, which are underproduced. By returning to the frequency distributions of u.r.v. (and u.r.w.) of the individual commodities which are likely to occur in Alaska, it is possible to estimate both what new resources may be expected and. very approximately. how much more of the resources already produced may be obtained in the future in Alaska. The annual value of the resources of Alaska from 1880 to 1972 may be treated as a time series and projections of future value may be made under different scenarios. This past history clearly emphasizes that the annual value of the mineral resources produced in Alaska is essentially determined by the “degree of commitment” given to investment in their development. This paper was presented at the International Geological Correlation Program (IGCP) Project 98: “Standards for Computer Applications ia Resource Studies” held at Taita Hills, Kenya, November 8–15, 1977. Par variable régionalisée. nous entendons une fonction d'espace, dont valeur varie d'un lieu à l'autre avec une certaine apparance de continuité, sans qu'il soit en général possible d'en représenter la variation par une loi mathèmatique extrapolable… Une teneur, dans un gisement minier, est une variable régionalisée.     

中国自然重砂分布特征及其意义

通过全国资源潜力评价,结合各省自然重砂资料和全国重砂资料汇总成果,对85个常见自然重砂矿物进行统计分析。研究表明,中国自然重砂矿物复杂多样,重砂矿物分布具有明显的区域性特点。造山带中自然重砂矿物产出数量相对较多且密度较大,而稳定地区重砂矿物相对较少。不同的自然重砂矿物及其组合具有明显的找矿信息,单矿物自然重砂可能来源于相对单一的矿石或岩石,其异常范围表明与其相关的矿产可能具有较好的成矿远景;矿物组合常显示出有关矿床的成因信息。自然重砂矿物与源区岩石或矿石具有密切的成因联系,对指导矿产勘查与研究具有十分重要的意义。     

An Upper Cretaceous (middle Campanian) marine chondrichthyan and osteichthyan fauna from the Rattlesnake Mountain sandstone member of the Aguja Formation in West Texas

A thin phosphate-granule conglomerate within the Upper Cretaceous (middle Campanian) Rattlesnake Mountain sandstone member of the Aguja Formation preserves a diverse chondrichthyan and osteichthyan fauna. This highly fossiliferous deposit (the ‘Ten Bits Microsite’) yielded about 5000 teeth, spines, and denticles in a small amount of matrix (c. 150 kg). About 30 identifiable species of sharks, rays, and bony fishes are recognized. Two of the three most abundant chondrichthyan species at Ten Bits (Scapanorhynchus texanus and Ischyrhiza mira) are also the most common species in other middle to late Campanian marine vertebrate faunas along the Gulf and Atlantic Coastal Plain. The myliobatiform rays Brachyrhizodus and Rhombodus that occur at Ten Bits also appear to be characteristic of the Gulf and Atlantic Coast, as are lamniform sharks such as Cretalamna and Serratolamna. These taxa are entirely absent or extremely rare in Western Interior Campanian faunas. In contrast, some small orectolobiform sharks (Cantioscyllium, Chiloscyllium, Columbusia) and small rays (Protoplatyrhina) found at Ten Bits are common in shallow water faunas of the Western Interior and Texas Coastal Plain, but rarely reported from the eastern Gulf or Atlantic Coast. The common Western Interior ray Myledaphus bipartitus does not occur at Ten Bits or in any Gulf or Atlantic Coast fauna. Ptychotrygon agujaensis is abundantly represented in the Ten Bits fauna, but unknown in correlative marine faunas. Although Ptychotrygon occurs in all Western Interior, Gulf and Atlantic Coastal Plain faunas, it is represented elsewhere by apparently endemic species at each collection site. The differences between Western Interior, Gulf, and Atlantic Coastal Plain faunas probably reflect latitudinal variation in water temperature or salinity, or different oceanic water circulation patterns between the Western Interior Seaway and the Gulf or Atlantic Coast that restricted the distributions of some marine fish species. The Ten Bits fauna shares typical species with both Western Interior and Gulf and Atlantic Coast faunas, reflecting its position at the border between these provinces; however, the dominant taxa found at Ten Bits are the same as those found on the Gulf and Atlantic Coast, and indicate that western Texas was more closely allied biogeographically with that province than with the Western Interior of North America. One species tentatively identified in the Ten Bits fauna on the basis of a single tooth, Igdabatis cf. I. indicus, is otherwise known only from southern Europe and Asia, although a similar large myliobatid ray also occurs rarely in Texas Coastal Plain faunas. These occurrences indicate that western Texas may have been near the northern limit of the range for some tropical Tethyan marine vertebrate species.     

大洋洲地区大地构造格架与优势矿产资源

大洋洲横跨印澳板块、太平洋板块和欧亚板块三大板块,区内从太古宙至今经历了漫长的构造演化历史。根据区域地质特征,该区可划分为3个一级构造单元,即澳大利亚中西部前寒武纪克拉通、澳大利亚东部古生代造山带和环太平洋中新生代岛弧区,12个二级构造单元和40个三级构造单元。3个一级构造单元由于经历了不同的构造演化过程,各自发育了不同的岩石组合和矿化作用。在研究区域构造演化与成矿作用耦合关系的基础上,总结出3个构造单元的成矿特征：澳大利亚中西部前寒武纪克拉通成矿过程与克拉通的生长有关,成矿时代主要为太古宙和元古宙,优势矿种为金、铜、镍、锰、铁、铀、稀土、铅锌、铝土等;东部古生代造山带成矿多和古太平洋与古冈瓦纳板块的相互作用有关,成矿时代为古生代,优势矿种为铜、金、铅锌和钨锡;环太平洋中新生代岛弧区的成矿作用多与印澳板块、欧亚板块与太平洋板块的相互作用有关,成矿时代多集中在中—更新世,优势矿种为铜、金、镍、钴等。对大洋洲地区矿产资源潜力进行了评估,认为大洋洲地区的铁、锰、铜、铝、镍、金、铀、稀土等矿产资源均具有较好的潜力。     

祁连成矿带成矿特征与资源潜力分析

新祁连成矿带由原祁连成矿带及柴达木主要的钾盐产地合并而成,横跨甘肃、青海、内蒙三省区,面积达11.4×104km2。成矿带大地构造位置处于华北陆块南缘与特提斯构造带交界部位,地质演化历史复杂,岩浆活动强烈。因此,该成矿带的成矿地质条件优越,所涵盖矿种齐全,是我国重要的黑色金属、有色金属及钾盐产地。本文在前人工作的基础上,对祁连成矿带的区域地质背景、重要矿产、典型矿产成因进行了系统分析,对主攻矿种成矿特征进行了研究,划分了成矿系列,建立了成矿谱系,并对资源潜力进行了评价。设定主攻矿种为钾盐、镍、钨,划分出7个主要成矿系列。在此基础上,部署了2个重点远景区:柴达木盆地西部重点远景区;金昌一般远景区。3个一般调查区:大道尔吉一般远景区;锡铁山重点远景区;下柳沟一般远景区,为指导本区勘查工作提供了依据。     

中国中、上扬子区石炭纪古构造沉积盆地类型

中、上扬子区石炭纪继承了加里东运动后的构造格局,滇中前寒武纪基底隆起区——康滇古陆(Ⅰ_1~1)不断向东扩大,与滇东早奥陶世后隆起区(Ⅰ_1~2)归拼。由于川中早志留后隆起区(Ⅰ_1~8)徐徐上升,它把川东鄂西泥盆世后隆起区(Ⅰ_1~(11))、以及武当、大洪山(Ⅰ_1~4)、湘西武陵山(Ⅱ_1~5)、雪峰山(Ⅱ_1~6)前寒武基底隆起区基本连在一起,从而使中、上扬子地块上的“中、上扬子古陆”雏形大致形成。晚泥盆世扬子古陆北缘被动大陆边缘盆地等与石炭纪早期基本相仿。湘、桂交界处,以龙胜-永福断裂为界,其西南为右江张性被动大陆     

大洋洲地区大地构造格架与优势矿产资源

大洋洲横跨印澳板块、太平洋板块和欧亚板块三大板块,区内从太古宙至今经历了漫长的构造演化历史。根据区域地质特征,该区可划分为3个一级构造单元,即澳大利亚中西部前寒武纪克拉通、澳大利亚东部古生代造山带和环太平洋中新生代岛弧区,12个二级构造单元和40个三级构造单元。3个一级构造单元由于经历了不同的构造演化过程,各自发育了不同的岩石组合和矿化作用。在研究区域构造演化与成矿作用耦合关系的基础上,总结出3个构造单元的成矿特征：澳大利亚中西部前寒武纪克拉通成矿过程与克拉通的生长有关,成矿时代主要为太古宙和元古宙,优势矿种为金、铜、镍、锰、铁、铀、稀土、铅锌、铝土等;东部古生代造山带成矿多和古太平洋与古冈瓦纳板块的相互作用有关,成矿时代为古生代,优势矿种为铜、金、铅锌和钨锡;环太平洋中新生代岛弧区的成矿作用多与印澳板块、欧亚板块与太平洋板块的相互作用有关,成矿时代多集中在中一更新世,优势矿种为铜、金、镍、钴等。对大洋洲地区矿产资源潜力进行了评估,认为大洋洲地区的铁、锰、铜、铝、镍、金、铀、稀土等矿产资源均具有较好的潜力。     

沉积成矿系列研究的新进展

沉积成矿系列强调沉积矿产组合与其成因关系、区域分布、在特定地质时代中的发育以及大地构造格局之间的关联性。本专题的研究成果是为沉积矿产资源的战略规划服务的。本文讨论了四方面的问题:(1)沉积成矿系列7大类型和形成因素;(2)中国大陆的7个沉积成矿系列区域;(3)从元古宙到第四纪沉积成矿系列对比的6大时代段;(4)关于沉积成矿系列集聚的两大主要控制作用。     

矿产资源集成评价

矿产资源评价与地质勘查工作有着密切的联系.20世纪60年代,世界各国政府开始关心一个国家或一个地区的矿产资源评价工作.近年来中国大陆矿产资源评价,逐渐由单一的地质经济评价、静态评价、普查勘探阶段评价向综合评价、动态评价、普查勘探和开发生产一体化评价转变.地理信息系统(GIS)在矿产资源评价中得到广泛应用.矿产资源集成评价是一种动态的、全球性的综合评价,具有预测、诊断功能.     

Quaternary tectonic faulting in the Eastern United States

Paleoseismological study of geologic features thought to result from Quaternary tectonic faulting can characterize the frequencies and sizes of large prehistoric and historical earthquakes, thereby improving the accuracy and precision of seismic-hazard assessments. Greater accuracy and precision can reduce the likelihood of both underprotection and unnecessary design and construction costs. Published studies proposed Quaternary tectonic faulting at 31 faults, folds, seismic zones, and fields of earthquake-induced liquefaction phenomena in the Appalachian Mountains and Coastal Plain. Of the 31 features, seven are of known origin. Four of the seven have nontectonic origins and the other three features are liquefaction fields caused by moderate to large historical and Holocene earthquakes in coastal South Carolina, including Charleston; the Central Virginia Seismic Zone; and the Newbury, Massachusetts, area. However, the causal faults of the three liquefaction fields remain unclear. Charleston has the highest hazard because of large Holocene earthquakes in that area, but the hazard is highly uncertain because the earthquakes are uncertainly located.Of the 31 features, the remaining 24 are of uncertain origin. They require additional work before they can be clearly attributed either to Quaternary tectonic faulting or to nontectonic causes. Of these 24, 14 features, most of them faults, have little or no published geologic evidence of Quaternary tectonic faulting that could indicate the likely occurrence of earthquakes larger than those observed historically. Three more features of the 24 were suggested to have had Quaternary tectonic faulting, but paleoseismological and other studies of them found no evidence of large prehistoric earthquakes. The final seven features of uncertain origin require further examination because all seven are in or near urban areas. They are the Moodus Seismic Zone (Hartford, Connecticut), Dobbs Ferry fault zone and Mosholu fault (New York City), Lancaster Seismic Zone and the epicenter of the shallow Cacoosing Valley earthquake (Lancaster and Reading, Pennsylvania), Kingston fault (central New Jersey between New York and Philadelphia), and Everona fault-Mountain Run fault zone (Washington, D.C., and Arlington and Alexandria, Virginia).     

尼日尔矿产资源开发现状

尼日尔是西非的一个内陆国家,工业基础薄弱,是世界上最贫穷的国家之一.尼日尔矿产资源丰富,特别是铀矿和油气资源潜力巨大,地质构造与演化历史独具特色.根据最新数据资料,以铀、石油、金、铁、煤、磷酸盐等矿产为重点,简要介绍了尼日尔矿产资源开发利用现状,综合分析了在尼日尔开展矿产勘查开发的主要矿业公司.在此基础上,提出了在尼日尔开展矿产勘查开发应加强镍、铂族元素及铁的勘探,应加强国际合作等若干对策建议.     

大别-苏鲁造山带在朝鲜半岛的延伸方式——基于~(40)Ar/~(39)Ar构造年代学的约束

本文结合野外构造变形特征观测,在朝鲜半岛的不同构造单元采集14件糜棱岩和片麻岩样品进行~(40)Ar/~(39)Ar年代学分析,在此基础上通过对比朝鲜半岛与大别造山带不同构造单元的变形特征,探讨大别苏鲁构造带在朝鲜半岛的东延特征,取得如下认识:朝鲜半岛中部的主要构造带在中生代经历了碰撞阶段(~210Ma)、逆冲推覆(200~150Ma)、造山后伸展阶段(140~90Ma)三个主要的构造过程;从变形期次和变形特征看,临津江构造带与大别造山带的北淮阳构造带、苏鲁构造带北部威海地区具有可比性,沃川构造带与南大别构造带有相似之处;在朝鲜半岛,自临津江带至沃川带构成了较完整的中生代碰撞造山带,即大别-苏鲁造山带的东延部分,原认为的"京畿地块"应属造山带的一部分。     

后危机时代矿产品价格趋势分析

通过对近50年来石油、铜、铝、镍价格变化趋势分析, 总结了矿产品价格长周期变化规律: 不变价格呈周期性下降趋势, 现价价格呈台阶状上升趋势。铜、铝、镍不变价格的绝对下降反映了人类技术进步带来生产效率的不断提高, 而石油不变价格的上升反映了资源稀缺程度对石油价格的重要影响; 由资源稀缺性决定的资源性商品的生产效率难以与其他商品生产效率同步提高, 必然以现价价格阶段性上涨实现价格平衡。结合矿产品成本、供需趋势和市场体系分析, 判断后金融危机时代矿产品价格平台为: 石油60～80美元/桶、铜3500美元/吨、铝2100美元/吨、镍14000美元/吨。     

赞比亚地质矿产与矿业投资前景分析

赞比亚是非洲第二大铜钴矿资源国,不仅云集了嘉能可集团和第一量子集团等国际矿业巨头,也是中资企业第四大境外矿业投资国,在非洲乃至世界矿业领域占据重要的地位。本文从构造演化与成矿的关系角度划分赞比亚的地质构造单元,并通过跟踪研究赞比亚矿产资源勘查开发动态和矿业投资政策变化情况,分析研判矿业国际投资发展前景。本文认为赞比亚从太古代到中-新生代经历了5个大的构造事件,形成了8个构造单元,随着复杂的地质构造运动,境内产出了砂页岩型铜钴矿床、VMS型铅锌矿床、花岗伟晶岩型锡钨钽矿床等丰富的矿产资源,但全国仅18%的矿业项目进入了生产阶段,矿业发展潜力巨大,同时其投资环境相对良好。在此基础上,本文提出在赞比亚开展矿业投资,需谨慎评估矿业政策和运输贸易成本方面的因素,最大化的利用投资激励政策和产业园区的优势,赞比亚将成为矿业国际产能合作的热土。