开放洞穴环境变化特征及其影响因素:以桂林凉风洞为例

通过对桂林凉风洞洞穴内、外温湿度、pCO2进行连续高频监测,发现洞穴温度受大气度温影响呈现出季节性变化规律。由于受到洞穴结构的阻隔作用影响,洞穴由外向里的温度变化幅度逐渐变小,并且响应的时间存在季节性差异。监测数据表明:洞穴内部温度的季节性变化幅度明显低于洞外气温变化幅度。比较洞内、外温度的时间序列发现,在季节尺度上洞穴温度升温阶段滞后时间长（与外部通风的气温流动交换慢）,降温阶段滞后时间短（与外部通风的气温流动交换快,呈现突变特征）,这可能与不同季节洞穴内部结构的“缓冲作用”的强弱变化有关。该洞穴空气中pCO2存在明显的夏季高、冬季低的季节性变化特征。并且外界大气环境季节性变化和洞穴上覆动植物的季节性活动,使得洞穴pCO2主控因素也存在季节性差异。      

The Taihua group on the southern margin of the North China craton: further insights from U–Pb ages and Hf isotope compositions of zircons

The "Taihua Group" is a collective term for a series of old terranes scattered along the southern margin of the North China Craton. The timing of formation and thermal overprinting of the Taihua Group have long been contentious, and its relationship with the Qinling orogenic belt has been unclear. In this study, new data from integrated in-situ U–Pb dating and Hf isotope analysis of zircons from an amphibolite (from the Xiong’ershan terrane) and a biotite gneiss (from the Lantian-Xiaoqinling terrane) indicate that the Upper Taihua Group formed during the Paleoproterozoic (2.3–2.5 Ga) and thus was originally part of the southern edge of North China Craton, detached during the Mesozoic Qinling orogeny and displaced about 100 km north from its original location. This suggests that the Taihua Group became part of the tectonic terrane associated with the Qinling orogeny and now forms part of the overthrust basement section of the Qinling belt. Before the Qinling orogeny, the Taihua Group was metamorphosed at 2.1 Ga. The initial Hf-isotope compositions of zircons, together with positive εNd(t) values for the whole-rocks, imply that the original magmas were derived from a juvenile source with some assimilation of an Archean crustal component.     

考虑场地和震源机制的近断层地震动衰减特性的研究

在收集了世界范围内自由场地的近断层地震记录基础上 ,综合考虑台站场地和震源构造机制的差别 ,应用统计分析方法对近断层地震动的峰值加速度、峰值比、特征比值及特定周期处的反应谱的衰减关系进行了研究 ,并和集集地震得到的结果进行了比较 ,发现场地和震源机制的共同作用对近断层地震动的影响是很显著的 ,为抗震设计规范的研究提供了参考     

山东南墅地区孔兹岩系变质矿物的成因及演化

南墅地区孔兹岩系的变质矿物具有多成因、多世代的特征 ,其经历三阶段五幕的变质作用 ,形成了以Sil+Gt +Cord +Bi +Kf +Pl+Q为代表的共生矿物组合。通过对主要变质矿物成因及演化特征的分析 ,结合温压计估算 ,确定该区孔兹岩系峰期变质作用温度为 70 0～ 75 0℃ ,压力为 0 .6～0 .7GPa ,变质程度达角闪麻粒岩相。确立 pTt轨迹具顺时针演化特点 ,反映一种陆 -陆碰撞造山带式构造演化模式。     

阿尔卑斯-喀尔巴阡上白垩统大洋红层特征与对比

在前人研究的基础上,从时代、岩性、古生物、沉积速率、沉积环境等方面对阿尔卑斯—喀尔巴阡地区的上白垩统大洋红层进行了详细对比,发现研究区内上白垩统大洋红层最早出露于Cenomanian期,最晚可延续至古近纪,且在Campanian期出露最为广泛,其岩性以灰岩、泥灰岩和含泥灰岩为主,生物化石以浮游有孔虫为主,沉积速率较低且在各地不尽相似,在CCD面上、下均可以出现,沉积环境一般是大陆边缘盆地、斜坡和大洋盆地等远洋、半远洋环境。通过比较分析,为进一步深入研究上白垩统大洋红层提供较为全面的基础资料。     

试论HACSAMT法

HACSAMT法在不增加任何设备、工作人员、工作时间的前提下,观测基波信号的同时,采集其高次谐波的振幅和相位的数据,大大地提高了劳动效率,而且,由于运用了谐波的有用信号,加密了CSAMT法勘探的频率,从而,提高了CSANT法的纵向勘探分辨率     

南秦岭石泉-汉阴北部煌斑岩脉特征及与金矿化的关系

羊坪湾矿区位于南秦岭南部逆冲推覆系迎丰-搁河口推覆体。北邻留凤关-金鸡岭褶皱束,西邻扬子准地台汉南凸起,南接北大巴山弧形褶皱带。矿区出露地层由南西向北东依次为洞河群（Z2-O）和下志留统梅子垭组（S1m）。其中洞河群分布于矿区的西南部,呈北西向展布,总体北东倾,倾角15°～45°,主要为硅质板岩,板岩中局部夹薄层炭质绢云石英片岩。下志留统梅子垭组倾向北东,倾角一般15°～50°,局部倾角最高可达75o,地层沿倾向及走向具波状起伏特征。梅子垭组以绢云石英片岩、二云石英片岩、含炭绢云石英片岩为主,以及夹有少量灰岩、大理岩条带等。金矿均赋存于志留系梅子垭组二云母石英片岩和含炭二云石英片岩中,以前者为主,约占90%以上。黄龙金矿区出露地层为下志留统梅子垭组,岩性为一套巨厚的浅变质细碎屑岩系,主要为绢云石英片岩、变砂岩、含黑云母变斑晶绢云石英片岩、含炭绢云石英片岩、含石榴子石黑云母变斑晶绢云石英片岩等。其中与矿（化）体关系最为密切的岩性为含炭绢云石英片岩、含黑云母变斑晶绢云石英片岩、含石榴子石黑云母变斑晶绢云石英片岩。     

Screening Effect of the Diffusive Boundary Layer in Sediments of Lake Aha in the Suburbs of Guiyang City,Guizhou Province

The redox cycle of iron and manganese is a major geochemica process at the boundary layers of lake sediments.Lake Aha,which lies in the suburbs of Guiyang City,Guizhou Province,China,is a medium-sized artificial reservoir with seasonally anoxic hypolimnion,Long-term sedimentary accumulation of iron and manganese resulted in their enrichment in the upper sediments,In the anoxic season,Fe^2 and Mn^2 ,formed by diological oxidation,would diffuse up to overlying waters from sediments.However,the concentration of oxidation,would diffuse up to overlying waters from sediments,However,the concentration of Fe^2 increased later and decreased earlier than that of Mn^2 .Generally,sulfate reduction occurred at 6 cm below the sediment-water interface.Whereas,in the anoxic season.the reduction reached upper sediments,inhibiting the release of Fe^2 ,The Fe concentration of anoxic water is quickly decreased from high to low as a result of reduction of the suplhur system.     

隧道施工地质超前预报方法

隧道施工地质超前预报是一项多种方法的综合运用,对预防异常情况及掌子面前方不良地质体的存在具有重要意义,其有利于安全施工、提高效率、缩短工期、避免事故,具有较大的社会效益和经济效益.通过合理组织预报作业流程、采用多种方法和对预测结果进行综合分析,能够提供更为准确的相关信息.