西藏东巧蛇绿岩中玄武质岩石成因和构造背景探讨

蛇绿岩记录了大洋裂解、俯冲消减和大陆增生的一系列过程,西藏北部班公湖-怒江缝合带中的蛇绿岩记录了青藏高原的地体拼合和隆升历史。班公湖-怒江缝合带中段的东巧蛇绿岩十分发育,地表出露较好,主要由地幔橄榄岩、堆晶杂岩、辉长辉绿岩和玄武岩组成。玄武岩呈多个露头产出,每个露头从十几平方米至数十平方米不等,辉绿岩呈脉状(或岩墙)产在玄武岩中。本文对东巧西出露的玄武岩和辉绿岩开展了详细的野外地质考察和室内岩相学、年代学和地球化学研究分析,探讨了该蛇绿岩的成因以及形成背景。研究表明,辉绿岩和玄武岩属低钾拉斑系列和钙碱性系列。辉绿岩轻稀土含量略高于N-MORB,兼具IAT和N-MORB的特征;玄武岩轻稀土相比重稀土稍富集,具有E-MORB的特征。样品的Nb/U值(30～48)均大于地壳平均值(10)以及(Th/Nb)N值(0.58～0.86)均小于1,表明岩石未遭受地壳混染。辉绿岩和玄武岩3个样品的锆石U-Pb年龄值均显示较大的变化区间,结合前人班怒带蛇绿岩年代学的研究成果,将其分为三组,第一组(156～239Ma)代表蛇绿岩自身的年龄,第二组(37～141Ma)为晚于蛇绿岩形成的年龄段,推测其为后期的岩浆事件成因,第三组(277～2454Ma)为早于蛇绿岩形成的年龄,推测其成因为原始地幔中残留的早期俯冲板片所携带的地壳中的锆石。通过岩石地球化学成分对比研究,认为辉绿岩和玄武岩为弧后盆地玄武岩(BABB)。结合前人地幔橄榄岩的研究,本文认为东巧玄武质岩石形成于俯冲带(SSZ)的弧后盆地扩张时期,并受到俯冲带流体不同程度的影响。     

内蒙古阿拉善北部雅干构造带白山组火山岩年龄、地球化学特征及其对区域构造演化的约束

阿拉善北部雅干地区古生代火山岩发育,研究其形成时代和地质特征,对探讨中亚造山带中段南缘北山弧盆系的演化具有重要的意义。对雅干地区原划奥陶系火山岩进行了同位素年代学与地球化学研究,获得流纹岩LA-ICP-MS锆石U-Pb年龄为298.4±1.5Ma,时代为早二叠世初期,结合岩石组合特征和区域对比,将其重新厘定为上石炭统—下二叠统白山组。该套火山岩富SiO2、高K2O、低TiO2,属于钙碱性系列; 相对富集Rb、Pb、K等大离子亲石元素,明显亏损Ta、Nb、P、Ti等高场强元素; 呈现为轻稀土元素相对富集、重稀土元素相对亏损的的右倾特征,具有较明显的负Eu异常,显示出陆缘弧火山岩的地球化学特征。上述证据表明,雅干地区白山组火山岩形成于古亚洲洋向明水-旱山地块北缘俯冲的陆缘弧构造环境。     

重庆彭水地区震旦系灯影组沉积地质新认识

重庆彭水太原乡老厂坪背斜核部的灯影组白云岩自下而上可划分为两段,下段"富藻",上段"富硅";沉积环境为浅水台地背景下的潮坪-局限台地,可据沉积物差异、沉积构造特征划分出潟湖、潮下、潮间及潮上四个微相类型。通过区域对比,建立了上扬子地区震旦系灯影组的沉积模式。纵向上,沉积相序表明其沉积时期海平面经历了两次升降变化,海侵十分短暂,海退为主体,海平面总体呈下降趋势;横向上,由北西至南东,水体逐渐加深,沉积环境经历了由潮坪-潟湖到局限台地-开阔台地,再到台地边缘以及陆棚的过渡。     

石灰稳定膨胀土的效用及其施工质量控制

膨胀土的胀缩可引起地基的变形，甚至危及构筑物的安全。对于膨胀土路段，路基的稳定是工程建设成功的关键。在论述石灰稳定土加固机理的基础上，结合工程实例，论述了膨胀土路段石灰稳定的施工要点及石灰稳定膨胀土路段的施工质量控制。     

大别造山带白马尖花岗岩体的钕，锶同位素地球化学研究

大别造山带白马尖花岗岩体属燕山期侵入岩，为中生代大别山区岩浆活动的产物，为碰撞后花岗岩，锶，钕，同位素数据及稀土元素数据表明，白马尖花岗岩体为壳幔混合型，1．2－1．7Ga的钕模式年龄为其源岩的平均地壳存留年龄，北大别花岗岩类岩石的物质来源并不一致。     

Status of Stratigraphy Research in China

Scientific research and productive practice for earth history are inseparable from the accurate stratigraphic framework and time framework. Establishing the globally unified, precise and reliable chronostratigraphic series and geological time series is the major goal of the International Commission on Stratigraphy(ICS). Under the leadership of the ICS, the countries around the world have carried out research on the Global Standard Stratotype-section and Points(GSSPs) for the boundaries of chronostratigraphic systems. In the current International Chronostratigraphic Chart(ICC), 65 GSSPs have been erected in the Phanerozoic Eonothem, and one has yet been erected in the Precambrian Eonothem. Based on the progress of research on stratigraphy especially that from its subcommissions, the ICS is constantly revising the ICC, and will publish a new International Stratigraphic Guide in 2020. After continual efforts and broad international cooperation of Chinese stratigraphers, 10 GSSPs within the Phanerozoic Eonothem have been approved and ratified to erect in China by the ICS and IUGS. To establish the standards for stratigraphic division and correlation of China, with the support from the Ministry of Science and Technology, the National Natural Science Foundation of China and the China Geological Survey, Chinese stratigraphers have carried out research on the establishment of Stages in China. A total of 102 stages have been defined in the "Regional Chronostratigraphic Chart of China(geologic time)", in which 59 stages were studied in depth. In 2014, the "Stratigraphic Chart of China" was compiled, with the essential contents as follows: the correlation between international chronostratigraphy and regional chronostratigraphy of China(geologic time), the distributive status of lithostratigraphy, the characteristics of geological ages, the biostratigraphic sequence, the magnetostratigraphy, the geological events and eustatic sea-level change during every geological stage. The "Stratigraphical Guide of China and its Explanation(2014)" was also published. Chinese stratigraphers have paid much attention to stratigraphic research in south China, northeast China, north China and northwest China and they have made great achievements in special research on stratigraphy, based on the 1:1000000, 1:250000, 1:200000 and 1:50000 regional geological survey projects. Manifold new stratigraphic units were discovered and established by the regional geological surveys, which are helpful to improve the regional chronostratigraphic series of China. On the strength of the investigation in coastal and offshore areas, the status of marine strata in China has been expounded. According to the developing situation of international stratigraphy and the characteristics of Chinese stratigraphic work, the contrast relation between regional stratigraphic units of China and GSSPs will be established in the future, which will improve the application value of GSSPs and the standard of regional stratigraphic division and correlation. In addition, the study of stratigraphy of the Precambrian, terrestrial basins and orogenic belts will be strengthened, the Stratigraphic Chart of China will be improved, the typical stratigraphic sections in China will be protected and the applied study of stratigraphy in the fields of oil and gas, solid minerals, etc. will be promoted. On the ground of these actions, stratigraphic research will continue to play a great role in the social and economic development of China.     

贵州福泉-凯里地区含铝岩系孢粉组合特征及形成时代研究

贵州福泉-凯里地区含铝岩系分布广泛,但其产出时代一直存在争议。本文运用孢粉年代学的方法,对凯里-福泉地区铝土矿4条典型剖面采集6件孢粉样品,讨论铝土矿的形成时代。研究表明:本次发现的孢粉样品中"四方十字粉Crucisaccites quadratoides、布氏厚角孢Triquitrites bransonii和固定三肩孢Tantillus perstantus等是贵州早二叠世时期最常见的特征属种,因此将本区铝土矿成矿时代限定为早二叠世。与黔北务正道地区铝土矿对比,含铝岩系孢粉组合特征与黔北务正道地区含铝岩系中孢粉组合特征相似度高,含铝岩系应形成于早二叠世紫松期-隆林阶,与黔北务正道地区大竹园组铝土矿形成时代相当。     

新疆卡拉麦里金矿带成矿规律及找矿预测

新疆卡拉麦里成矿带内地层较全、构造发育、岩浆活动频繁，志留系、泥盆系和石炭系在带内广泛发育，为本区主要含金地层．卡拉麦里深断裂严格控制区内侵入岩、次一级构造和矿产分布，构成岩浆侵入的主要通道，与此有关的次一级断层和裂隙则构成良好的赋存空间．卡拉麦里深大断裂纵贯全区，金成矿地质条件优越，沿走向Au异常、金矿床(点)成群成带分布，最后确定了7个金找矿远景区．     

民和盆地中侏罗统煤-油页岩层系生油特征

本文简要论述了民和盆地中侏罗统含煤及油页岩层系的生油特征，探讨了盆地独特的石油地质和地球化学条件。原油主要地化特征为:Ｐｒ/Ｐｈ比值偏高（２.６５-３.１５）、甾烷/藿烷比值极低（０.０３）、Ｃ_２７甾烷较丰富、Ｔｓ/Ｔｍ＞１低硫芴/氧芴比值、较高含量的Ｃ_２９降新藿烷及重排藿烷类化合物及相对丰富的长链联苯及烷基四氢萘系列化合物。中侏罗统煤－泥页岩层系含生油潜力明显不同的多类型油页岩，多数油页岩属由藻类和陆生高等植物母质组成的混合型有机质，沉积环境为淡水－微咸水弱氧化条件，其地化特征也表现为高Ｐｒ/Ｐｈ比值（平均为１。９８），低甾烷/藿烷及低硫芴/氧芴比值等特征。某些油页岩富含Ｃ_２９降新藿烷及重排藿烷系列化合物，它们应为主力源岩。油页岩多含再沉积型或沉积改造型有机质。异常地热作用对源岩演化及原油地化特征有重要影响。     

岩体水力学基础(三)──岩体渗流场与应力场耦合的集中参数模型及连续介质模型

本文在分析了岩体系统的结构性和水力学特征后，提出了岩体渗流场与应力场耦合数学模型的机理分析、混合分析及系统辨识建模方法。运用系统辨识方法建立了岩体渗流场与应力场耦合的集中参数模型，并应用于解决实际问题；运用机理分析和混合分析方法建立了岩体渗流场与应力场双场耦合及与温度场三场耦合的连续介质分布参数模型。