塔西台地寒武纪沉积环境演化与海陆耦合

碳酸盐岩台地作为陆地与深海间的过渡带,其沉积记录了海洋和邻近陆地的演化。结合已有的沉积学工作,对塔里木盆地西部台地寒武系碳酸盐岩进行全岩及酸不溶物地球化学研究。塔西台地寒武纪主要发育局限台地、局限-蒸发台地或蒸发台地相沉积。碳酸盐岩的地球化学特征主要受沉积环境和成岩作用影响,对研究区寒武系白云岩来说,其元素组成极易受沉积微相的控制,氧同位素组成则很可能已被成岩作用改造,仅原生、准同生白云岩的Sr/Ba、Fe/Mn和C同位素可反映沉积相演化对应的古盐度、离岸距离等沉积环境特征的变化,酸不溶物化学蚀变指数（CIA值）则指示邻近陆地的化学风化强度与气候特征。寒武纪时期,塔西台地在相对海平面较高时发育局限台地相沉积,以水体盐度较低、沉积环境离岸较远和生物活动相对较弱为特征,陆地化学风化强度适中,气候温暖湿润;在相对海平面较低时发育蒸发台地相沉积,具有水体盐度较高、沉积环境离岸较近和生物活动相对较强等特点,陆地化学风化强烈,气候炎热极端;在相对海平面适中时发育局限-蒸发台地,沉积环境和邻近陆地的特征介于前述二者之间。沉积相演化对应的较长周期的海陆演化可能主要受全球海平面升降及宏观气候变化控制,具体表现为相对海平面升降所导致的海相沉积环境的变化,以及气候变化引起的陆地化学风化强度的变化。寒武纪塔西台地所处区域的海洋-陆地演化具有高度耦合的特征。     

Occurrence and conceptual sedimentary model of Cambrian gypsum-bearing evaporites in the Sichuan Basin,SW China

During the Cambrian, gypsum-bearing evaporites formed in the Sichuan Basin, SW China. These rocks are important for oil and gas sealing, but details of their distribution and origin are not well established. This study examines the regional distribution and origin of the gypsum-bearing evaporites using a comprehensive analysis of drilling data from 34 wells, 5 measured cross-sections in the basin and surrounding area, and 96 maps of area-survey data. Results show that in the stratigraphic succession, the gypsum-bearing evaporites occur mainly in the Lower Cambrian Longwangmiao Formation, the Middle Cambrian Douposi Formation, and the Middle-Upper Cambrian Xixiangchi Group. Geographically, the rocks are found mainly in the southeastern part of the basin, and the distribution of deposits shows an overall SW-NE trend. The sedimentary environments for evaporite formation were evaporative lagoon and inter-platform basin in a platform setting. Gypsum was generated by the underwater concentration of sea water in a strongly evaporative environment. Both an evaporative restricted platform and a mixeddeposition restricted platform model appear to be applicable to the development of gypsum in the Sichuan Basin. The gypsum-bearing evaporites with the best sealing capacity are located mostly in the southeastern part of the basin. These constraints can be applied directly to regional exploration, and have implications for the regional paleogeography and paleoclimate.     

Isotope stratigraphy and U-Pb dating of detrital zircons from the Vendian-Cambrian deposits of the North Muya block

U-Pb dating of detrital zircons from the sandstones of the Mamakan Formation has been made. Geochemical and isotope parameters of the carbonate deposits of the Yanguda Formation in the Vendian-Cambrian cover of the North Muya continental block have been estimated. It has been established that only the Neoproterozoic (630-915 Ma) rocks of the North Muya block were the provenances of terrigenous material. In the least altered carbonate rocks of the Yanguda Formation, the ⁸⁷Sr/⁸⁶Sr ratio is within 0.70814-0.70879 and δ¹³C varies from -0.4 to + 1.9‰. Comparison of the evaluated isotope parameters with those of carbonate rocks of typical Vendian-Cambrian sections shows that the carbonate deposits of the Yanguda Formation accumulated in the Early Cambrian, about 520 Ma. Sedimentation of the Mamakan and Yanguda Formations took place in the local sedimentary basin in the Vendian-Early Cambrian, in the absence of tectonic activity within the North Muya block. Detrital material that formed during the destruction of the rocks of the Siberian Platform basement and cover was not supplied into the basin.     

Phenanthrene biomarkers in the organic matter of Precambrian and Phanerozoic deposits and in the oils of the Siberian Platform

The composition and distribution of phenanthrenes (polyaromatic compounds) have been studied in chloroform extracts from dispersed organic matter (OM) of clayey, siliceous, carbonate, and terrigenous rocks of different ages and facies and from some oils of the Siberian Platform. Phenanthrenes have been analyzed by gas chromatography-mass spectrometry. High contents of 1,7,8-trimethylphenanthrene and 1,1,7,8-tetramethyl-1,2,3,4-tetrahydrophenanthrene are present in the OM of Vendian and Cambrian carbonate-shale deposits and in ancient oils of the Nepa-Botuobiya and Anabar anteclises. The OM of Permian continental deposits and oils of the Vilyui syneclise is dominated by 1-methyl-7-isopropylphenanthrene (retene). A triangular diagram for identification of the types of original OM of rocks and classification of genetically related oils has been constructed based on the assessment of phenanthrene biomarker distribution. Putative pathways of the formation of phenanthrene biomarkers are discussed.     

关于《中国扬子区兰多维列统特列奇阶及其与英国的对比》一书若干问题的商榷

《中国扬子区兰多维列统特列奇阶及其与英国的对比》一书（陈旭,戎嘉余,1996）有以下结论：①将回星哨组、茅山组、西坑组等的层位归属于特列奇阶上部;②将回星哨组、茅山组及其相当地层与英国特列奇阶对比;③将扬子区特列奇阶的顶界置于回星哨组、茅山组及其相当地层之顶;④将回星哨组、茅山组、西坑组等地层资料编制的古地理图称为特列奇期晚期古地理图;⑤将回星哨组、茅山组、西坑组等地层与上覆中泥盆统—中二叠统之间的不整合面代表的上升运动,称为“特列奇期的扬子上升”。笔者等依据多年对扬子地台志留纪地层剖面的实地考察和近数十年来扬子区坟头组中—上部、茅山组、回星哨组、小溪峪组、西坑组等地层中文洛克世、拉德洛世、普里多利世早期古生物化石的发现,认为：①回星哨组、小溪峪组、茅山组、西坑组等的层位是文洛克统—普里多利统;② 回星哨组、小溪峪组等大致与英国的文洛克统—普里多利统对比;③回星哨组、小溪峪组、茅山组的顶界是文洛克统—普里多利统剥蚀后残留的层位随地而异的顶界;④根据回星哨组、西坑组、茅山组等地层资料编制的古地理图应是文洛克世—普里多利世古地理图;⑤“扬子地台整个上升”（黄汲清,1945）的时代是志留纪末期,没有“特列奇期的扬子上升”。特提出商榷。上述这些地层时代的解决,对扬子区志留系4统层序的建立具有重要意义,而且也为中国扬子区与英国命名剖面志留系的对比以及中国南方早古生代加里东运动最后一幕时代的再次确定提供了地层学和古生物方面的依据。     

Organic Carbon Isotopic Evolution during the Ediacaran-Cambrian Transition Interval in Eastern Guizhou, South China： Paleoenvironmental and Stratigraphic Implications

Secular variations of carbon isotopic composition of organic carbon can be used in the study of global environmental variation, the carbon cycle, stratigraphic delimitation, and biological evolution, etc. Organic carbon isotopic analysis of the Nangao and Zhalagou sections in eastern Guizhou reveals a negative excursion near the Precambrian-Cambrian boundary that correlates with a distinct carbonate carbon isotopic negative excursion at this boundary globally. Our results also demonstrate that several alternating positive and negative shifts occur in the Meishucunian, and an obvious negative anomaly appears at the boundary between the Meishucunian and Qiongzhusian. The isotope values are stable in the middle and lower parts but became more positive in the upper part of the Qiongzhusian. Evolution of organic carbon isotopes from the two sections in the deepwater facies can be well correlated with that of the carbonate carbon isotopes from the section in the shallow water facies. Integrated with other stratigraphic tools, we can precisely establish a lower Cambrian stratigraphic framework from shallow shelf to deep basin of the Yangtze Platform.     

山西地堑系一类特殊的剪切-挤压型地裂缝

阐述了山西地堑系的构造背景及现今应力场状态,对该地区发育的地裂缝特点进行了概括性描述。根据实际调查,在该地区发现了一类特殊的剪切-挤压型地裂缝万荣县城关变电所地裂缝,该地裂缝地貌上位于山西地堑系峨嵋台地,发育特征表现为强烈的剪切、挤压变形,地面、墙体拱曲、翘起,并出现明显的水平位错现象。与该区发育的其他地裂缝有明显的不同。根据地裂缝发育的特征,并结合区域构造应力场分析,讨论了该地裂缝的力学成因机制。     

Hill Instability Analysis of TLP Tether Subjected to Combined Platform Surge and Heave Motions

This paper presents the Hill instability analysis of Tension keg Platform （TLP） tether in deep sea. The 2-D nonlinear beanl model, which is undergoing coupled axial and transverse vibrations, is applied. The governing equations are reduced to nonlinear Hill equation by use of the Galerkin＇ s method and the modes superposition principle. The Hill instability charted up to large parameters is obtained. An important parameter M is defined and can be expressed as the functions of tether length, the platform surge and heave motion amplitudes. Some example studies are performed for various envirotnnental conditions. The results demonstrate that the nonlinear coupling between the axial and transverse vibrations has a significant effect on the response of structure. It needs to be considered for the accurate dynamic analysis of long TI2 tether subjected to the combined platfolna surge and heave motions.     

华北区域分米级北斗地基增强服务系统构建及精度分析

利用国家级北斗连续运行基准站和省级区域北斗CORS站,基于国家卫星导航定位服务平台,通过改造和直接利用的方式,在华北平原构建了我国首个跨区域北斗分米级地基增强服务系统。经采用双频终端实地测试,该系统覆盖京津冀晋全部区域及内蒙古部分区域,采用GPS+北斗双模定位静态精度达到分米级,动态定位精度达到亚米级,单北斗模式定位精度略低,但仍在分米-亚米量级,极大地提高了我国北斗导航系统的高精度应用能力,拓宽了我国北斗民用导航的应用范围和领域,可满足高精度北斗实时导航、定位服务的应用需求。     

寒武纪丝状蓝细菌生物膜主导和诱发的巨型鲕粒:以河南新安县石井剖面苗岭统徐庄组为例

多样化的产出环境和30×108年的分布历史表明,鲕粒成因一直是一个谜一样的沉积学难题,争论的关键问题是其究竟是有机(微生物)成因还是无机成因.来自于华北地台寒武系苗岭统徐庄组鲕粒滩相灰岩顶部的方解石巨鲕表现出同心状、放射—同心状和泥晶质的沉积组构,在鲕粒核心和鲕粒皮层中保存着精美的葛万菌(Girvanella)化石所主...