南极半岛周边海域表层沉积物粒度分布特征及其环境指示意义

基于南极半岛周边海域表层沉积物调查以及收集的资料,并通过分析表层沉积物粒度数据研究沉积物类型和分布特征,探讨沉积物的变化规律。南极半岛周边海域的沉积物类型比较丰富,主要分为四大类:砾质、砂质、粉砂质以及泥质沉积物;根据不同的水深和地貌单元可分为陆架(或岛架)碎屑沉积物、陆坡(或岛坡)沉积物和深海沉积物。研究区沉积物属于冰海沉积物,并可划分为残副冰碛物和混合副冰碛物。沉积物的搬运介质以冰川、冰筏为主,海流对沉积物的影响较为明显,沉积物类型随地形变化而呈有规律的分布。     

金沙江支流黑水河松新电站短须裂腹鱼（Schizothorax wangchiachii）过坝后上溯行为

鱼类过坝后的上溯行为对鱼类寻找适宜的产卵、索饵等功能性栖息地至关重要。现阶段我国大多数研究聚焦于鱼类上溯通过鱼道的游泳行为量化,而过坝后的上溯行为分析鲜有报道。本研究在金沙江下游支流黑水河松新坝址处利用PIT(passive integrated transponder)遥测技术对松新电站过鱼对象短须裂腹鱼(Schizothorax wangchiachii)过坝后的上溯行为开展监测,考虑监测过程中水文情势变化对过坝后上溯行为的影响,采用生存分析方法,构建了耦合多因素(流量、水温、河道涨落水率、昼夜节律、肥满度等)的Cox风险比例回归模型,利用AIC模型准则筛选出最优模型参数,识别了影响鱼类过坝后上溯成功率的关键因素。结果表明:(1)短须裂腹鱼在松新鱼道的上溯效果显著优于河道;(2)水温及河道涨落率是影响短须裂腹鱼过坝后上溯效果的关键因素;(3)水温与短须裂腹鱼过坝后河道上溯成功率呈负相关,当水温超过短须裂腹鱼最适温度后,河道上溯成功率随着温度的上升呈递减趋势;河道涨落水率与短须裂腹鱼过坝后河道上溯成功率呈正相关,其中涨水情势下短须裂腹鱼河道成功上溯的概率高于落水,河道上溯成功率随着涨...     

A remote sensing model for monitoring soil evaporation based on differential thermal inertia and its validation

To develop geosciences quantification and multi-dimensional researches will be an inevitable trend in the 21st century. The interaction between the land surface and the atmosphere not only serves as an important component in geosciences quantification, bu…     

Denudation rates of crystalline rock in the Huangling anticline of the Three Gorges of the Yangtze River in China since the Eocene

The processes and rates of the weathering denudation of the bare crystalline rock are important problems in the field of geosciences[1—6]. Essentially, the weathering denudation process is the process of rock destruction and transportation. In different …     

改进磁变仪布局的研究

本文讨论了各分量磁变仪磁针之间的相互影响以及地磁场各分量的变化、记录光入射角对记录的影响，并由此认为一套磁变仪的布局应满意三项标准：（１）各分量仪磁针间的相互静磁影响要小，且任一磁针受其它磁针工作的影响要低于该分量仪记录的分辨率；（２）各分量仪的状态函数稳定，即保持定向能力强；（３）可产生较高精度的线性记录磁照图。鉴于目前的磁变仪布局与此三标准有明显差距，故本文提出了一种新的布局方案，可满足此三项     

陆态网络GNSS基准站阶跃偏移量的精确估计

通过对发生阶跃的GNSS基准站坐标序列谱指数的求解,表明了其具有有色噪声的特性,并对三分量分别建立了最优噪声模型,以此对GNSS基准站坐标的阶跃偏移量进行了精确估计,探明了地震和仪器更换对测站产生的精细影响。同时利用求解的阶跃偏移量对坐标序列进行修正,对获取连续性变化的测站坐标序列和获取精确的测站三维运动参数具有重要意义。     

Skarn-type tungsten mineralization associated with the Caledonian (Silurian) Niutangjie granite,northern Guangxi,China

The Niutangjie tungsten deposit is a bedded skarn-type scheelite deposit and is located at the junction between Ziyuan and Xingan counties in the north of Guangxi,China.The deposit is genetically related to a fine-grained two-mica granite within the orefield.Zircon LA-ICP-MS U-Pb dating of the granite yielded a Silurian(Caledonian)age of 421.8±2.4 Ma,which is contemporaneous with the adjacent Yuechengling batholith.Mineralization within the skarn is associated with a quartz,garnet,and diopside gangue,and scheelite is present in a number of different mineral assemblages,such as quartz-scheelite and quartz-sulfide-scheelite;these assemblages correspond to oxide and sulfide stages of mineralization.Sm-Nd isotope analysis of scheelite yielded an isochron age of 421±24 Ma.Although the uncertainty on this date is high,this age suggests that the scheelite mineralization formed during the Late Caledonian,at a similar time to the emplacement of the Niutangjie granite.Zircons within the granite have?Hf(t)values and Hf two-stage model ages of?6.5 to?11.6,and 1.79 to 2.11 Ga,respectively.These data suggest that the magma that formed the granite was derived from Mesoproterozoic crustal materials.Scheelite?Nd(t)values range from?13.06 to?13.26,also indicative of derivation from ancient crustal materials.Recent research has identified Caledonian magmatism in the western Nanling Range,indicating that this magmatism may be the source of contemporaneous tungsten mineralization.     

Geochemistry and genesis of authigenic pyrite from gas hydrate accumulation system in the Qilian Mountain permafrost,Qinghai, northwest China

A type of authigenic pyrites that fully fill or semi-fill the rock fractures of drillholes with gas hydrate anomalies are found in the Qilian Mountain permafrost; this type of pyrite is known as “fracture-filling” pyrite. The occurrence of “fracture-filling” pyrite has a certain similarity with that of the hydrate found in this region, and the pyrite is generally concentrated in the lower part of the hydrate layer or the hydrate anomaly layer. The morphology, trace elements, rare earth elements, and sulfur isotope analyses of samples from drillhole DK-6 indicate that the “fracture-filling” pyrites are dominated by cubic ones mainly aligned in a step-like fashion along the surfaces of rock fractures and are associated with a circular structure, lower Co/Ni and Sr/Ba, lower ΣREE, higher LREE, significant Eu negative anomalies, and Δ³⁴S_CDT positive bias. In terms of the pyrites’ unique crystal morphology and geochemical characteristics and their relationship with the hydrate layers or abnormal layers, they are closely related with the accumulation system of the gas hydrate in the Qilian Mountain permafrost. As climate change is an important factor in affecting the stability of the gas hydrate, formation of fracture-filling pyrites is most likely closely related to the secondary change of the metastable gas hydrate under the regional climate warming. The distribution intensity of these pyrites indicates that when the gas hydrate stability zone (GHSZ) is narrowing, the hydrate decomposition at the bottom of the GHSZ is stronger than that at the top of the GHSZ, whereas the hydrate decomposition within the GHSZ is relatively weak. Thus, the zone between the shallowest and the deepest distribution of the fracture-filling pyrite recorded the largest possible original GHSZ.     

磁变仪布局的研究

本文提出了改进磁变仪布局的必要性和布局标准,对磁变仪定向及其稳定性、标度值稳定性和分量仪间允许的最小间距进行了研究,提出了可以提高磁变仪记录质量的改进布局和满足布局全部标准的新布局,改进布局特别是新布局可以显著提高磁变仪保持定向、抗干扰能力,获得记录标度值稳定的较理想的磁照图。     

CT诊断胸部平片隐匿部位肿瘤的检出价值

本文对２２７例胸部肿瘤中的３４例Ｘ线不易发现的肿瘤进行了Ｘ线与ＣＴ诊断的对照分析,此组病例共占胸部肿瘤的１４．９％,胸部隐匿部位的肿瘤在传统Ｘ光正位胸片上受组织重叠的影响是不易看到的,容易漏诊,须通过ＣＴ扫描检查方可观察到,ＣＴ扫描是诊断胸部隐匿部位肿瘤的最好,最有效的检查方法之一。