地震前电磁辐射信息特征研究

反映电磁辐射信息的地震前异常变化很多,但都有一个震前平静－加强－平静然后发震的特征,为了更好地体现这种特征,根据十几年来河北廊坊电磁台网的观测资料,通过给不同强度段的各台日信息量赋予不同的权值,并把当日各台权值累加来反映当日内多台信息量集中的强弱,然后把上述权累加和用一种不连续积分的方法反映异常的持续时间,通过对监测范围内４次Ｍｓ≥５．０地震震例分析,发现该方法反映震前异常特征明显,短临效果很好,     

金刚石与深部碳循环

深部碳循环是全球碳循环研究中不可或缺的部分。较之表层碳,人类对地球深部碳储库的储量、碳的迁移方式和交换量都缺乏清晰认识。作为来自地球深部的碳单质矿物,金刚石是研究深部碳循环的绝佳样品。近年来原位微区分析技术的突飞猛进为研究金刚石及深部碳循环提供了良好条件。文中对表层与深部碳交换、深部碳储库及金刚石矿物学性质进行了介绍,并通过金刚石及其包裹体的稳定同位素组成,探讨了金刚石的形成机制及含碳流体/熔体的性质与来源问题。     

Geochronology and petrogenesis of the post-orogenic Cu–Ni sulfide-bearing mafic–ultramafic complexes in Jilin Province, NE China

Northeastern (NE) China is a well-documented example of a collisional zone characterized by widespread post-orogenic granites and mafic–ultramafic complexes. Based on a study of the Hongqiling and Piaohechuan Cu–Ni sulfide-bearing mafic–ultramafic complexes in central Jilin province, we present geological, petrological, geochemical and geochronological data which indicates their post-orogenic origin.The Hongqiling complex comprises pyroxenite, olivine websterite, lherzolite, gabbro and leucogabbro. Zircon U–Pb SHRIMP analyses on a leucogabbro of the Hongqiling complex yield a weighted mean ²⁰⁶Pb–²³⁸U age of 216±5 Ma. The Piaohechuan complex is composed of gabbro, pyroxenite and dolerite, exposed as dikes. A plagioclase-bearing pyroxenite has a U–Pb zircon weighted mean ²⁰⁶Pb–²³⁸U age of 217±3 Ma, identical to that of the Hongqiling complex. These ages are coeval with the emplacement of A-type granites in the area, but slightly younger than the regional metamorphism (240 Ma) and syn-orogenic granitic magmatism (246±4 Ma). This suggests that these mafic–ultramafic complexes are post-orogenic in origin. The age data also indicated a short period of lithospheric stabilization of about 30 Ma after cessation of orogenic activity.Geochemical investigation indicates that the primary mafic magma was a lithospheric mantle-derived basalt resulting from the upwelling of asthenosphere due to lithospheric delamination during post-orogenic processes. The magmatic source was contaminated by a small amount of crustal material, and subsequent crystal fractionation resulted in the Cu–Ni mineralization.The widespread occurrence of mafic–ultramafic complexes in the Xing'an–Mongolian Orogenic Belt of NE China and in the Altay–Tianshan–Junggar Orogenic Belt of Northern Xinjiang indicates that mafic intrusions are an important magmatic suite that evolved during post-orogenic processes. Portions of this mafic magma could have underplated the lower crust, and served as the heat source for associated late-stage granitic magmas.     

估算地表热通量和近地层土壤含水量的变分方法

提出一种反演地表感热通量、潜热通量和近地层土壤含水量的变分方法,该方法把不同高度上的风速、位温以及湿度梯度的观测资料与Monin-Obukhov相似理论计算值的偏差、土壤水分蒸发参数化方案估算的蒸发潜热与由相似理论导出值的偏差在地表能量平衡的约束下融合到一个目标泛函数中,采用最优化算法寻求问题的解.利用2001年6月中国暴雨试验与研究项目在安徽肥西观测资料进行了数值验证,结果表明该方法估算的通量值与Bowen比法具有很好的相关性且又能克服当Bowen比等于-1时计算通量出现的不稳定;同时能克服用廓线法求解热通量与地表能量平衡条件有较大出入的缺点.对观测误差的敏感性试验也表明变分方法是3类方法中最稳定的.反演的近地层土壤含水量对降水具有很好的响应并与观测的0-15 cm深度上平均土壤湿度的变化趋势具有很好的一致性,其绝对偏差小于0.03 m3/m3.     

辽宁海洋综合经济区划分的初步探讨

我国是海洋大国，有相当陆域国土面积三分之一的海洋国土。随着海洋资源的开发利用，海洋经济不断发展，海洋经济区逐渐形成。在全国划分经济区时，不应忽视海洋经济区。沿海省区在划分经济区时，更应把海洋列入到省级经济区内。辽宁是我国沿海省区之一，通过对辽宁海洋经济区划分的研究，探讨海洋经济区及其划分的有关理论、实践与方法。     

核地球物理和化探综合测量在上海市区工程地质调查中的应用

本文介绍在上海市区断裂构造调查中 ,核地球物理测量和化探的应用效果。应用α卡、地面伽马能谱U、Th、K和总量 (Σ)及壤中气汞等测量方法 ,采用组合指标推断断裂构造 ,推断出的断裂构造与地震推断的结果相比较 ,具有较好的一致性。这些方法经济、快速、有效 ,有着广泛的应用前景     

Variability in the vertical hyporheic water exchange affected by hydraulic conductivity and river morphology at a natural confluent meander bend

River confluences and their associated tributaries are key morphodynamic nodes that play important roles in controlling hydraulic geometry and hyporheic water exchange in fluvial networks. However, the existing knowledge regarding hyporheic water exchange associated with river confluence morphology is relatively scarce. On January 14 and 15, 2016, the general hydraulic and morphological characteristics of the confluent meander bend (CMB) between the Juehe River and the Haohe River in the southern region of Xi'an City, Shaanxi Province, China, were investigated. The patterns and magnitudes of vertical hyporheic water exchange (VHWE) were estimated based on a one‐dimensional heat steady‐state model, whereas the sediment vertical hydraulic conductivity (K_v) was calculated via in situ permeameter tests. The results demonstrated that 6 hydrodynamic zones and their extensions were observed at the CMB during the test period. These zones were likely controlled by the obtuse junction angle and low momentum flux ratio, influencing the sediment grain size distribution of the CMB. The VHWE patterns at the test site during the test period mostly showed upwelling flow dominated by regional groundwater discharging into the river. The occurrence of longitudinal downwelling and upwelling patterns along the meander bend at the CMB was likely subjected to the comprehensive influences of the local sinuosity of the meander bend and regional groundwater discharge and finally formed regional and local flow paths. Additionally, in dominated upwelling areas, the change in VHWE magnitudes was nearly consistent with that in K_v values, and higher values of both variables generally occurred in erosional zones near the thalweg paths of the CMB, which were mostly made up of sand and gravel. This was potentially caused by the erosional and depositional processes subjected to confluence morphology. Furthermore, lower K_v values observed in downwelling areas at the CMB were attributed to sediment clogging caused by local downwelling flow. The confluence morphology and sediment K_v are thus likely the driving factors that cause local variations in the VHWE of fluvial systems.     

新疆阿尔泰阿勒泰组沉积时代及其形成环境

阿勒泰组变质碎屑岩局部夹变质火山岩广泛分布于南阿尔泰的冲乎尔、克兰和麦兹盆地,其沉积时代和构造环境对于研究阿尔泰造山带的演化过程有重要意义。阿勒泰组碎屑锆石的年代学研究表明,碎唐锆石年龄主要集中在417-383 Ma和507-445 Ma,并出现少量元古宙和太古宙碎屑锆石。少数锆石年龄为380-354 Ma,与阿勒泰组凝灰岩和流纹岩年龄一致(376~354 Ma)。综合研究认为阿勒泰组时代为中-晚泥盆世(382-354 Ma)。阿勒泰组长石石英砂岩分选性和磨圆度较差,为近源沉积,物源岩石主要来自泥盆纪火山岩,其次是晚寒武一早奥陶世火山岩和奥陶纪花岗岩。长石石英砂岩样品具有高的La/Sc(3.9-6.3),La/Y(1.0~1.6),较低的Sc/Cr(0.2~0.4)比值,类似于大陆岛弧相关环境碎屑沉积物,结合Th-Co-Zr/10和Th-Sc-Zr/10以及La-Th-Sc判别图,认为阿勒泰组形成于与岛弧相关的构造环境(弧后盆地),为研究阿尔泰造山带泥盆纪构造演化提供了重要证据。     

吉林省下三叠统卢家屯组LA-ICP-MS锆石U-Pb定年及其地质意义

卢家屯组按岩性组合自下而上分为影背山砾岩段、漏斗山杂色岩段、杨树河子黑色岩段,前人采集到的Palaeanodonta-Palaeomutela动物群、Pleuroneia? sp.和叶肢介等生物化石组合指示时代为二叠纪。本次对九台市影背山双顶山卢家屯组建组剖面下、中、上段进行了系统的碎屑锆石U-Pb同位素年代学研究,证实卢家屯组由下至上存在3个最小锆石年龄峰值,分别为(283.4±7.9)、(262.4±3.9)、(255.5±5.8) Ma,确定了卢家屯组的上限为晚二叠世。根据卢家屯组中碎屑锆石存在1 800 Ma和2 500 Ma左右的典型华北板块基底年龄,认为华北板块北缘与其北侧地块群最终闭合时间应为P₃-T₁。     

发展与不发展南海扰动的能量收支与转换特征

利用多年逐月海温距平和区风应力距平观测资料,运用线性回归和ＥＯＦ分析方法,分析了ＥＮＳＯ相联系的热带太平洋典型风应力异常场结构。结果显示,与ＥＮＳＯ线性相关的风应力异常场在时间尺度上表现为低频变化,在水平结构上主要表现为四个典型分布。