羌塘盆地最大规模沥青脉的发现及其意义

在羌塘盆地已经发现了190余处油气显示。近年笔者在盆地北部晚侏罗世地层中发现了迄今最大规模的沥青脉。研究结果表明，该沥青脉产出于上侏罗统索瓦组地层之中，地层下部系与沥青脉的形成有一定关系的中株罗统夏里组局部含油气显示的盐丘。沥青族组分(％)为：饱和烃5．72、芳烃18．46、沥青质52.37、非烃23．45，说明核沥青脉经过了运移、氮化的过程。同时，沥青脉产出于复背斜范围内，利于油气聚集成藏。这一发现对于羌塘盆地的油气地质的作用具有现实意义。     

怎样写好中英文摘要

经国家科委批准,中国地质大学《地质科技情报》向国内外公开发行。为使国内外读者迅速获得所需的信息和线索,本刊要求来稿附中英文摘要。现就如何写妤中英文摘要谈一点看法,供投稿者参考。一、写好中英文摘要的意义在当今信息时代,写好文章摘要具。有重要意义摘要以最简明扼要的语言表达文章最重要、最基本、最核心的内容。它有利于读者在最短的时间里了     

变质成矿的理论基础(续)

由热力变质作用和超变质作用引起的岩石中化学元素的迁移.区域热力变质作用和超变质作用能引起原岩中原生组分的重结晶,而超变质作用能引起原岩部分的或完全的重熔.低变质相特点是岩石的脱水和大部分自生矿物的重晶,同时,易溶元素,特别是金属产生很强的活动性.随着变质作用的增强,组成岩石的矿物被溶解,然后完全重结晶.在所有的带均能见到由变质分异所产生的矿化水流引起的交代现象.在这些作用的影响下,矿石物质大量迁移,导致造矿元素重新分配并富集.     

Trace metals in fish and invertebrates of three California coastal Wetlands

Metal concentrations were measured in selected fish and invertebrate species from Mugu Lagoon, Malibu Lagoon and Ballona Wetlands in southern California in order to assess the extent of metal contamination in these three wetlands. Ranges of element concentrations (in microgram/g) found in biota were: Zn 12-650; Cu 1.9-440; Ni < 1-37; Cr < 1-55; Pb < 0.5-6.8; As < 1-8.5; Se < 1-3.8; Cd < 0.2-0.90; and Ag < 0.3-5.9. Relative to previous studies of California biota, the highest metal concentrations found were for chromium and nickel. The highest levels were in one of the two bottom-dwelling fish (juvenile Leptocottus armatus) (55 micrograms/g) and the two water-column fish sampled (Fundulus parvipinnis and Atherinops affinis) (30 and 24 micrograms/g). At Ballona Lagoon, elevated levels of copper and silver were found in the bivalve Tagelus californianus (440 and 5.9 micrograms/g). Chromium and nickel appeared to be most persistent in fish from Mugu (4.6-55 and 2.6-37 micrograms/g), the most northern site and an active military base, and Ballona (< 1-30 and < 1-16 micrograms/g), believed to be the most metal-contaminated site. Compared to previously measured metal concentrations in species of California coastal waters, these regions revealed higher levels of chromium, nickel, silver, arsenic, zinc, copper and, to a lesser extent, cadmium and selenium. Chromium and silver were present at high enough levels at all three sites to be considered environmental health hazards.     

青藏特提斯沉积地质演化

组成青藏高原的主要微板块在不同的阶段经历了各具特色的地质演化历程和发展特点，形成了不同的地壳结构。青藏高原的沉积地质历史演化 经历了区内各主要微板块的基底形成与盖层沉积演化 的前特提斯阶段；以板块汇聚边缘与碰撞时期的构造背景为基础，划出古特提斯、中特提斯和新特提斯三个沉积叶质历史发展及其所形成的弧盆体系格架的特提斯形成演化阶段；随着始新世末期残留海的消失，青藏地区形成统一大陆，并进入统一应力场的青藏统－陆壳形成阶段；从中上新世开始的青藏高原隆升阶段，青藏高原上发育了一些大中型中新生代沉积盆地，如羌塘盆地、措勤盆地、昌都盆地等都经历过从弧后向盆地向前陆盆地转化的演化阶段，并具有受喜马拉雅运动统一改造的特征，这些沉积盆地中油气藏前景良好。     

Hydrocarbon degraders from tropical marine environments

Analysis of 20 samples of marine mud and water around Mumbai resulted in the isolation of 17 bacteria and yeasts all of which were able to degrade more than 10% of the supplied crude oil. The yeasts strains were important degraders of the aliphatic fraction of crude. All the isolated yeasts belonged to the genus Candida. Using biochemical tests these were identified as Candida parapsilosis, C. albicans, C. guilliermondii, Yarrowia lipolytica, C. tropicalis and C. intermedia. Y. lipolytica was the best degrader utilizing 78% of the aliphatic fraction of Bombay High crude oil. None of these isolates degraded the aromatic or ashphaltene fractions. All the isolates required aeration, nitrogen and phosphate supplementation for optimal degradation. Four out of the six yeasts are human pathogens.     

宁镇地区燕山期侵入岩锆石U-Pb定年:长江中下游新一期成岩成矿作用的年代学证据

对宁镇地区3个典型燕山期岩体(安基山-伏牛山岩体、下蜀-高资岩体和石马岩体)的中酸性侵入岩进行LA-ICP MS锆石U-Pb定年,给出(109.1±1.9)~(101.6±1.1)Ma的年龄值,代表了这些侵入岩体的形成年代,为该地区中酸性侵入岩形成时代提供了精确的约束。宁镇地区铜-多金属成矿作用在时间、空间和成因上与100~110Ma左右的中酸性钙碱性岩浆活动相关联,区内成岩成矿作用是一个连续的过程。宁镇地区燕山期中酸性侵入岩形成于早白垩世晚期,而长江中下游九瑞等地区的同类型侵入岩形成于早白垩世早期,二者相差约25~35Ma;结合白垩纪以来太平洋板块活动特征对中国东部陆区成岩成矿的制约,这些年代学数据揭示出宁镇地区燕山期岩浆活动及其成矿响应是中生代长江中下游成矿带大规模岩浆-成矿活动的新一期成岩成矿事件,深部地球动力学背景对应中国东部中生代岩石圈拆沉-减薄事件。长江中下游地区的岩石圈减薄从135Ma左右开始,可能持续到100Ma左右。