大洋富钴结壳成因机制的探讨——水成因证据

根据对大洋富钴结壳的分层与年龄、分层与生长速率、生长间断等观测事实,以及大洋富钴结壳主量元素锰、铁元素及钴元素、铂元素、稀土元素、氦同位素、锇同位素等的水成富集,指出大洋富钴结壳是水成因的,进而指出富钴结壳的形成与基岩无关,水动力条件、最低含氧带、生物作用等可能对富钴结壳的形成有控制作用。同时,富钴结壳不一定只生长在岩石裸露的海山上,在沉积物覆盖的海山区也有可能找到富钴结壳。     

白垩纪以来中国西部地体运动的古地磁证据和问题

地质证据表明中国西部各地体在白垩纪之前已经增生到欧亚大陆之上 ,但这些地体自白垩纪以来的古地磁极位置与稳定欧亚大陆的古地磁极位置存在较大差异 ,对其最可能的解释是发生在晚白垩世与古新世之交 (约 6 5Ma)印度板块和欧亚大陆之间的碰撞及其后印度板块的持续北向挤压 ,使得这些地体之间以及这些地体与稳定欧亚大陆之间发生了相对位移和地体内部的变形。文中利用现有的古地磁研究成果 ,计算了自白垩纪以来中国西部各地体与欧亚稳定大陆之间的南北向相对位移量。塔里木地块和柴达木地体的古地磁数据表明 ,阿尔金断裂至少经历了四期活动。在欧亚地区普遍存在的第三纪磁倾角偏缓现象 ,很可能反映了在该地区长期存在非偶极子场。     

鄂东南富水金矿带成矿地质特征及找矿标志

本文介绍了富水金矿带区域地质、金矿带地层、构造及典型矿床地质特征,矿床属中、低温渗滤热卤水型金矿-卡林型金矿,金为微细粒浸染型金,肉眼甚至一般光学显微镜中均不可见。作者根据本区金矿体的分布及赋存情况,结合区域成矿地质条件和化探异常分布,对金矿带找矿标志进行了总结。     

东天山康古尔金矿成矿晚阶段地幔流体参与成矿作用的碳氢氧同位素证据

康古尔金矿位于塔里木板块北部被动大陆边缘阿奇山-雅满苏裂谷带之北侧,是一个典型的韧性剪切带型(造山型)金矿,成矿作用表现为含金石英脉和石英碳酸盐脉两个阶段。本文对矿石中的碳酸盐脉和矿床周围地层中的碳酸盐岩进行了C、H、O同位素测试。通过研究初步认为:矿床周围地层石炭纪干墩组和雅满苏组中大理岩的C、O同位素组成与世界上其他地区的海相碳酸盐基本相同,以富~(13)C和~(18)O为特征,明显有别于矿石中碳酸盐脉;后者的C、H、O同位素组成与地幔多相体系中的原始碳酸岩基本相似,暗示在康古尔金矿成矿晚阶段有地幔流体参与成矿作用。     

岩浆作用对海底热液系统物质的贡献

系统地总结分析了国内外关于岩浆作用对热液系统物质贡献的证据和研究成果。在此基础上,进一步分析了岩浆作用对热液系统物质贡献的主要形式,并对近期研究工作的主要方向进行了探索性分析。提出岩浆作用对热液系统物质贡献的形式除了传统的岩-水反应外,还有岩浆后期热液及挥发性组分直接进入的途径(形式);对海底热液活动系统的研究工作近期应主要集中在3个方面:(1)利用新近发展的高新技术,强化矿物及包裹体的原位微区分析,获取更加精细的矿物形成过程中的原始信息。(2)非传统稳定同位素的开发应用,为解决悬而未决的科学问题发展新的技术手段。(3)进一步发展完善岩浆作用对热液系统物质贡献的理论模型,更加贴近实际地定量评价岩浆作用对热液系统的物质贡献。上述工作,无疑对推进海底热液活动研究的进一步深化具有重要意义。     

东北北部冻土退化与寒区生态环境变化

我国东北地区位于中高纬度欧亚大陆东缘,大、小兴安岭多年冻土区是欧亚大陆高纬冻土区向南最突出的部位,属于高纬山地冻土.东北多年冻土区是我国,乃至全球范围内,受气候变暖和人为活动影响最显著的冻土区之一.过去40 a来该区冻土显著退化,主要表现在:1)冻土南界及不连续多年冻土各分区边界北移而导致总面积减小、空间分布破碎化;2)活动层加深,融区扩大,局地冻土岛消失;3)冻土温度升高、厚度减薄、热稳定性降低等.由于各种因素的共同影响,寒区生态环境也发生了一系列变化.这具体表现为以兴安落叶松占绝对优势的天然林带锐减,整个北方森林带北移,沼泽湿地面积减小等,寒区生态系统和环境已出现恶性循环.关注、研究、整治和管护寒区环境对区域社会、经济和生态可持续发展不可或缺.     

GEOMORPHIC EVIDENCES FOR CENOZOIC UPLIFT IN THE EASTERN MARGIN OF QINGHAI—TIBET PLATEAU

GEOMORPHIC EVIDENCES FOR CENOZOIC UPLIFT IN THE EASTERN MARGIN OF QINGHAI—TIBET PLATEAU     

水母(沙海蜇)降解与营养盐(氮、磷)释放的模拟与实证

The aim of this study was to investigate nitrogen and phosphorus released in the process of the decomposition of giant jellyfish in the laboratory and found the evidence to verify the influence of nutrients released by the decomposition of jellyfish on the ecosystem in the field. The release of nitrogen and phosphorus from the decomposition of Nemopilema nomurai was examined in a series of experiments under different incubation conditions such as different p H values, salinity values, temperatures and nitrogen and phosphorus concentrations. The results showed that the complete decomposition of Nemopilema nomurai generally took about 4–8 d. The release of nitrogen and phosphorus from the decomposition of Nemopilema nomurai could be divided into two stages: the early stage and the later stage, although the efflux rate of nitrogen was one order more than phosphorus. In the early stage of the decomposition of Nemopilema nomurai, the concentrations of dissolved nitrogen, dissolved phosphorus, total nitrogen and total phosphorus in seawater increased rapidly, and the concentration of nitrogen could reach the highest level in the whole degradation process. In the later stage of the decomposition, the concentrations of dissolved nitrogen and total nitrogen declined slowly, while the concentration of phosphorus in water could reach a maximum in the degradation process. High p H, low salinity,high temperature and N/P will promote the release of nitrogen; low p H is unfavorable to the release of nitrogen but favorable to the release of phosphorus. In addition, we found the concentrations of ammonium and phosphate in the bottom water were higher than those in the surface water during the period of jellyfish bloom in the Jiaozhou Bay, proving that nutrients released by the decomposition of jellyfish have significant influence on nitrogen and phosphorus in the field. For the whole Yellow Sea, nutrients released by jellyfish carcasses may reach up to(2.63±2.98)×107 mol/d of dissolved nitrogen(DN) and(0.74±0.84)×106 mol/d of dissolved phosphorus(DP) during the period of jellyfish bloom. The values are comparable to riverine inputs in a day, but much higher than sediment–water exchange flux in the Yellow Sea. The great amounts of nutrients must have significant influence on the nutrients balance of the Yellow Sea during the period of jellyfish dead and decomposition. Both the experimental data and field observations proved that the decomposition of jellyfish may release a great amount of nutrient to the surrounding environment during the period of jellyfish decomposition.