吉林省太古宙TTG岩类固结的温度压力条件

吉林省太古宙ＴＴＧ岩类型成于变质上壳岩系麻粒岩相变质作用晚期阶段。详细的岩相学研究表明，ＴＴＧ岩类中存在岩浆结晶的绿帘石，角闪石和黑云母等。绿帘石的出现标志了一定的压条件。     

从江汉叠合盆地构造形变特征看华南与华北陆块的拼贴过程

构造解析表明,现今观察到的中扬子地区中部江汉叠合盆地主体构造格架面貌大体形成于印支 早燕山碰撞造山期;其中,主造山初期前陆盆地发育阶段,盆区东、西部构造形变差异明显,晚期经调整而渐趋平衡,由此显现华南与华北两大陆块在碰撞造山过程中可能先后经历了早期点状接触与陆间斜向俯冲和晚期线状接触与陆内俯冲两个发展阶段。晚燕山期以来,盆地裂陷阶段构造格架的分区发育与右行旋转特点,证明中扬子地区曾发生过双向伸展和构造旋转作用,暗示晚燕山 早喜马拉雅期华南与华北两大陆块可能处于逐渐焊合的过程,研究区总体处于造山后陆内应力场调整阶段。盆地坳陷期发育阶段山盆非耦合面貌及壳幔“立交桥”式结构特征展示晚喜马拉雅期以来叠合盆地南、北边缘造山带已进入去根与裂解过程中。     

粟类作物稃片植硅体形态研究回顾与展望

中国是粟、黍的起源地,但受植物遗存保存状况及研究方法的限制,对粟类旱作农业起源与驯化的时间、地点、种类、过程等的认识仍然存在不同观点。植硅体分析为准确鉴定粟、黍及其野生祖本和亲缘物种提供了新的途径。本文总结了近几年来针对粟、黍种子稃片植硅体研究取得的新进展,获得以下认识：1）进一步明确了稃片表皮长细胞植硅体的形态特征、大小、数量是鉴定考古文化堆积中粟、黍及其野生祖本和亲缘野生物种的可靠指标;2）通过对比我国北方常见的狗尾草属稃片植硅体,发现了ΩⅢ型仅发育于粟和青狗尾草的稃片中部,且其大小与狗尾草属野生植物差异显著;3）分析和说明了稃片植硅体鉴定流程和方法、重点强调了稃片Ω/η类型的鉴定特征和应用范围,以及植硅体统计量等关键问题;4）讨论了粟类稃片植硅体产量与农作物产量的关系以及植硅体埋藏学问题,最后对深化粟类植硅体形态学研究提出了初步建议。希望通过本文的总结与讨论,能够使植硅体分析方法在粟类作物起源和传播的研究中得到更准确、更广泛的应用。

     

黄土高原表土磁化率与气候要素的定量关系研究

黄土高原地区已建立多个表土低频磁化率-气候转换函数,为黄土古气候定量重建提供了关键方法。但是表土磁化率变化的气候控制因素的系统研究尚未开展; 同时,低频磁化率部分受到沉积作用的影响,需要寻找气候意义更明确的指标。我们系统采集了黄土高原及周边地区的表土样品,运用相关、回归和因子分析等方法,研究了不同气候要素及其季节变化对表土磁化率和频率磁化率的控制作用。结果显示,湿度是控制黄土高原表土磁化率的主要因素,温度的影响相对较小; 降水的季节分配也有影响,月降水变率较小的地区磁化率较高。在此基础上,选择反映成壤磁性颗粒组分的频率磁化率,建立了频率磁化率-年均降水量的转换函数,为黄土古气候定量估算提供了新的途径。     

Estimation of Grassland Production in Central and Eastern Mongolia from 2006 to 2015 via Remote Sensing

Mongolia is an important part of the Belt and Road Initiative “China-Mongolia-Russia Economic Corridor” and a region that has been severely affected by global climate change. Changes in grassland production have had a profound impact on the sustainable development of the region. Our study explored an optimal model for estimating grassland production in Mongolia and discovered its temporal and spatial distributions. Three estimation models were established using a statistical analysis method based on EVI, MSAVI, NDVI, and PsnNet from Moderate Resolution Imaging Spectroradiometer (MODIS) remote sensing data and measured data. A model evaluation and accuracy comparison showed that an exponential model based on MSAVI was the best simulation (model accuracy 78%). This was selected to estimate the grassland production in central and eastern Mongolia from 2006 to 2015. The results show that the grassland production in the study area had a significantly fluctuating trend for the decade study; a slight overall increasing trend was observed. For the first five years, the grassland production decreased slowly, whereas in the latter five years, significant fluctuations were observed. The grassland production (per unit yield) gradually increased from the southwest to northeast. In most provinces of the study area, the production was above 1000 kg ha ^-1, with the largest production in Hentiy, at 3944.35 kg ha ^-1. The grassland production (total yield) varied greatly among the provinces, with Kent showing the highest production, 2341.76×10 ⁴ t. Results also indicate that the trend in grassland production along the China-Mongolia railway was generally consistent with that of the six provinces studied.     

Numerical study of sand scour with a modified Eulerian model based on incipient motion theory

Application of the standard Eulerian model to simulations of sand scour results in unrealistic phenomena. Therefore, the present work develops a modified Eulerian model based on sand incipient motion theory. The modified model is applied for simulating a two-dimensional single vertical jet and a moving planar jet. The simulation results generally demonstrate fairly good agreement with published results of scour profiles and the velocity contours of the water and sand phases. In addition, equations to describe self-similar scour profiles for the moving planar jet cases are given. The results demonstrate that the modified model efficiently and accurately simulates the two-dimensional sand scour produced by jets, particularly for the moving jet cases.     

成矿流体动力学与大地构造环境的关系(英文)

热液矿床的形成需要大量流体,而流体的运移需要包括地势差、岩石变形、热梯度及热异常等多种驱动力。这些流体驱动力与构造环境及过程有密切关系。流体压力状态和热场及地势差的组合决定了压性构造环境流体以向上运动为主,如造山型成矿系统,而张性构造环境流体以对流为主,如VMS和SEDEX成矿系统。造山作用造成的地势差及水平挤压作用所产生的超压可以驱动流体侧向迁移数百公里,如MVT成矿系统。但是,具体的成矿流体动力学过程比较复杂,且随构造演化而变化。在经历过多个大地构造演化阶段的地区,如地洼区,老的成矿流体动力系统不断被新的系统叠加或取代;新的构造单元需要来自地幔的流体源补充才有利于成矿。成矿学研究的是成矿作用与大地构造的关系,而流体动力学系统与大地构造环境密切相关,因此,成矿流体动力学应成为成矿学的一个重要组成部分。     

1—3年强震危险区预测的指标体系

强震危险区预测是当前地震预报中的重要课题之一。笔者以预警活断层、预警活断层分段研究解决断层活动的时间和空间尺度为主线，配合地震活动动态分析、地震波介质特征早期信息、近场趋势性前兆异常和危险性概率预测，确定了判别几年尺度强震危险区的指标。在“八五”地震科技课题研究过程中，圈这了范围不超过１００００ｋｍ＾２的５个强震危险区，已成功地对１９９３年１０月２日若羌６．６级地震、１９９５年５月２日乌苏５．８级     

An alternative deduction of the hill-type surfaces of the spatial 3-body problem

In the present paper, inequalities stronger than Sundman's and the best possible zero velocity surfaces of the spatial 3-body problem first obtained by Saari (1987) are deduced using a modified version of the transformation developed by Zare (1976). The notion of inertia ellipsoid is used to show the equivalence of the present authors' result to that of Saari's.     

青藏高原羌塘盆地晚侏罗世索瓦期沉积特征研究

为推进我国石油工业发展丰富石油地质理论,根据野外露头及室内分析化验资料,建立8种相标志,识别出索瓦期沉积相类型有：台地相、台地边缘相、盆地相和海陆过渡相、湖泊相。受北部拉竹龙-金沙江缝合带、中央隆起带和南部班公湖-怒江缝合带的影响,沉积相呈近东西向展布,具南北分带的特点。文章分析了索瓦期的沉积特征,总结了该期的沉积模式。根据研究区的生物特征和沉积特征,推断当时气候是温暖、半干旱的。综合分析认为,索瓦组是羌塘盆地很有潜力的油气勘探目的层,其与上覆雪山组地层可构成有利的含油气组合;而双湖-多涌地区是首选的含油气有利区带。