地层含金银性评价的地球化学准则——以扬子地台北缘中段中上元古界为例

金银丰度的高低不是控制金银矿化的决定性因素。有利于金矿化的因素包括:较高的金银丰度;全银的几何平均值与算术平均值比较;金分布及银分布均为多峰偏态,对数分布为正态-正偏;易释放金比例高;地层中金银形成的元素组合同区域金银矿床的矿化元素组合接近。     

新疆中库鲁克塔格地区震旦系扎摩克提组沉积特征

扎摩克提组位于中库鲁克塔格震旦系上统底部,由砂岩、粉砂岩和泥页岩构成韵律武沉积,为不完整的玛鲍序列.砂岩层底面普遍发育槽模等底痕.有些砂岩呈纹层状,并有滑动构造和包卷层理等.构成砂岩的碎屑颗粒分选性差.根据粒度分布概率图、C-M图和碳、氧、硫等稳定同位素及Sr/Ba比值、硼含量等显示,该组形成于淡化海槽中.     

Total ozone response to major geomagnetic storms and changes in meteorological situations

Summary The total ozone response to strong major geomagnetic storms (A_p≥60) in winter along the 50° N latitudinal circle is studied. The results add to the recent results of Laštovička et al. (1992) obtained for European middle latitudes (∼50°N) and to the results of Mlch (1994). A significant response of total ozone is only observed in winter under high solar activity/E-phase of QBO conditions (E-max) and seems to be caused by geomagnetic storm-induced changes of atmospheric dynamics. There are two sectors along latitude 50°N, which are sensitive to forcing by geomagnetic storms both in total ozone and the troposphere — north-eastern Atlantic-European and eastern Siberia-Aleutian sectors. The total ozone response under E-max conditions manifests itself mainly as a large decrease in the longitudinal variation of ozone after the storm, which means an increase of ozone in Europe. The observed effects in total ozone consist in redistribution, not production or loss of ozone.     

High-Resolution Seismic Reflection Evidence for Middle Holocene Environmental Change, Owasco Lake, New York

Approximately 70 km of new decimeter-resolution seismic reflection profile data from Owasco Lake, New York define a middle Holocene (4600 ¹⁴C yr B.P.) erosion surface in the north end of the lake at water depths as great as 26 m. Beneath the lake, post-glacial sediments are up to 9 m thick and represent about 10% of the total sediment fill. Early to middle Holocene sediments, 6 m thick, contain biogenic gas at the south end of the basin and a large (4 km×300 m×15 m) subaqueous slide deposit along the east-central portion of the lake. Late Holocene sediments are thinner or absent, particularly at the north end of the lake. The middle Holocene erosion surface may have been produced by a drop in lake level. Alternatively, it may represent a change in climate during the transition between the relatively warm Holocene hypsithermal and cool neoglacial. At this time (4600 ¹⁴C yr B.P.) circulation in Owasco Lake appears to have evolved from sluggish to active. The increased circulation, which persists today, probably resulted from atmospheric cold fronts with strong southwesterly winds that piled up water at the north end of the lake. The increased water circulation may have been ultimately driven by decreasing insolation, which produced an increased pole-to-equator thermal gradient and, thus, stronger global winds that began at the transition between the hypsithermal and neoglacial.     

图们江流域中更新世火山泥石流分布及其特征

图们江流域中更新世火山泥石流仅分布在残留的Ⅲ阶地上，碎屑物的粒级范围很广，具正粒序层理，分选差，是在冰川作用或冰雪融化作用下快速搬运、沉积形成的，具有浊积岩的沉积模式。     

黑龙江盘古-碧水韧性剪切带中段构造地球化学特征

盘古-碧水韧性剪切带中段糜棱岩的叠加强度和质量平衡分析表明:剪切带在变形过程中组分发生了显著的交换。糜棱岩类总体CaO、K₂O、SiO₂大量带入,TiO₂、MnO、FeO是带出的。随着糜棱岩化程度的提高,SiO₂、K₂O、MnO明显带入,CaO少量带出。以Al₂O₃守恒为限制条件,整个剪切带质量和体积增加了16.87%。大规模的物质带入带出发生在糜棱岩阶段。     

我国中部地带农业现代化建设途径探讨

中部地带是我国农业的精华地带，目前，我国农业发展中面临的部分农产品结构性剩余严重，市场竞争力弱，农业劳动生产率和土地生产力低而不稳，农民收入增长放慢，农业持续发展的后劲不足等问题在中部地带表现更为典型，探索中部地带农业现代化建设的实施途径对于研究和解决当前我国农业发展面临的诸多问题都具有重要的作用。中部地带农业现代化途径主要是：整体规划，分类推进，极点突破；改革城乡户口隔离机制，加速农村城镇化；创新土地流转机制，培育规模经济的现代农业市场主体；创新科技机制，发挥高科技对农业的带动作用；拓宽农产品加工领域加大农产品市场建设力度。     

盆中丘陵区生态恢复重建的生态与经济效益亟待提高

以紫色岩为背景的盆中丘陵区 ,是构建长江上游生态屏障的重点地区。近 10多年来 ,以林木植被恢复重建为主要内容的生态建设取得了显著成效 ,平均森林覆盖率已达到 2 2 %。但是 ,森林植被生态系统的生态与经济功能尚处于较低的水平 ,其中桤柏混交林生态系统开始出现退化的趋势 ,纯柏林面积日趋扩大 ,病虫害逐年增多。为此需应用生态学和经济学原理 ,实施农村生态经济工程建设的途径 ,把该地区生态建设推向一个新的水平。     

藏北高原双湖地区中侏罗统海相油页岩生物标志化合物分布特征及其意义

重点报道了藏北双湖地区中侏罗统海相油页岩的生物标志化合物特征,首次在该层位油页岩中检出丰富的正烷烃、类异戊二烯烷烃、萜类化合物及甾类化合物。正烷烃图谱呈单峰形,nC₁₅、nC₁₆或nC₁₇为主峰碳,轻烃组份占有绝对优势,OEP值 0.93～ 1.0 1,无明显的奇偶碳数优势分布;Pr/Ph值为 0.77～ 1.5 9,在剖面序列中呈波动分布,显示弱植烷优势或姥鲛烷优势;藿烷以C₃₀ 占优势,萜烷相对丰度五环三萜烷 >三环萜烷 >四环萜烷;规则甾烷∑ (C₂₇+C₂₈) >∑C₂₉,∑C₂₇/∑C₂₉值为 0.79～ 1.2 0,在剖面序列中下部C₂₇甾烷略占优势,上部C₂₉甾烷略占优势,重排甾烷C₂₇/规则甾烷C₂₇值为 0.5 1～ 3.6 3,在剖面序列中具有显著的波动性,同时检出了少量孕甾烷和 4-甲基甾烷。有机质母质构成中,既有丰富的藻类等低等水生生物,可能还有一定比例陆生高等植物输入混合的特点。油页岩处于成熟阶段,整个油页岩剖面序列具有一致的热演化程度。剖面中部油页岩具有极高的原始生产力,氧化-还原条件也是控制油页岩TOC和沥青“A”含量在剖面垂向变化的重要因素.