广西南丹地区泥盆纪台间海槽沉积环境分析

广西“南丹型”泥盆系以黑色泥岩为主,富含浮游生物竹节石等,是一套受基底构造控制的并受其两侧碳酸盐台地影响的台间海槽沉积。沉积相类型主要为深水含竹节石泥岩相,泥灰岩相及硅质岩相。台间海槽从益兰期开始出现,其形成和发展在塘丁—纳标—榴江期,封闭可能在早石炭世之后。     

山西宁武地区全新世以来气候与环境变化

根据野外实测剖面、室内测试分析,笔者通过对山西宁武地区全新世以来的湖相沉积地层的孢粉、易溶盐、pH值、磁化率、碳酸盐和粒度分析,探讨了该区全新世以来的气候与环境变化过程。结果表明该区全新世以来的气候变化可划分为4个阶段112400~10000aB.P.期间,显示气候干冷,但有逐渐变暖的趋势;210000~8000aB.P.期间,气候较温湿;38000~3000aB.P.期间,气候温暖;4距今3000aB.P.~现代,气候出现3次波动,整个气候向干凉方向发展。对山西宁武地区湖相沉积地层的进一步深入调查与研究,将会确定华北地区的全新世以来环境与气候变化的基本规律。     

陆源碎屑与碳酸盐混合沉积研究中的几点思考

在前人研究的基础上，结合一些具体研究实例，对混合沉积的定义进行了修正和补充；对混积岩和混积层系重新进行分类和命名；根据混合沉积的定义、成因、成分、结构、沉积构造及接触关系等因素，按照“沉积事件+剖面结构”的原则，提出了渐变式、突变式和复合式3种成因类型，对前人的研究成果进行了概括和归纳；对混合沉积的控制因素进行了深入讨论；在以碳酸盐沉积为主和以陆源碎屑沉积为主的2类沉积背景下详细论述了层序格架中混合沉积的发育情况；结合混合沉积本身的特点讨论了混合沉积与油气的关系。最后针对混合沉积研究现状，指出了该领域研究中存在的问题，并对未来的研究方向进行了展望。     

西藏南部聂拉木地区侏罗纪—白垩纪盆—山转换过程中的沉积学响应

西藏南部聂拉木—定日地区沉积地层记录着侏罗纪被动大陆边缘到白垩纪前陆盆地的盆—山转换演化历史。侏罗纪发育巨大的海侵—海退沉积序列，晚侏罗世喜马拉雅特提斯海底扩张速度明显加快，从0.32 cm/a上升为1.24 cm/a。前陆盆地演化分为早期深水复理石和晚期海相磨拉石两个阶段。前陆早期发育向上急剧加深的深水砂泥质复理石建造、黑色页岩建造和岛弧型火山岩建造沉积；前陆晚期海相磨拉石沉积总体表现为向上变粗、变浅的沉积序列。     

西秦岭地区晚二叠世—早三叠世沉积相分析和沉积古环境再造

青海省同仁地区处于祁连和秦岭造山带的接合部，构造演化历史悠久。本次工作在该地区隆务河一带发现较好的二叠—三叠系剖面。将该剖面从下而上划分为上二叠统石关组、下三叠统果木沟组和江里沟组，其中江里沟组又进一步划分为下部的浊积岩段和上部的风暴岩段，初步确定了二叠—三叠纪的界线。沉积序列、沉积相和沉积物表明上二叠统石关组和下三叠统果木沟组为一套陆源碎屑浊积岩，下三叠统江里沟组下部为一套不纯的内碎屑浊积岩，而下三叠统江里沟组上部为风暴岩沉积。根据沉积相和火山岩夹层的地球化学特征认为该地区上二叠统石关组和下三叠统果木沟组处于半深海的活动大陆边缘，下三叠统江里沟组早期的浊积岩段处于较稳定的半深海大陆边缘。根据沉积相和遗迹化石，恢复了晚二叠世—早三叠世的海平面变化特征。     

西藏羌塘盆地东部中-上侏罗统沉积特征及沉积相划分

详细野外剖面测量基础上,对羌塘盆地东部中-上侏罗统剖面主要岩类的宏观特征(颜色和构造)、物质组分、结构及磁化率等特征进行系统研究,研究区碎屑岩主要为砾岩、砂岩、粉砂岩和泥岩等岩类,磁化率值呈现低→高→低→高→低(雀莫错组→布曲组→夏里组→索瓦组→雪山组)的规律性变化。综合沉积特征显示雀莫错组和雪山组主要为河流相-河控三角洲相沉积,布曲组为碳酸盐缓坡相沉积为主,夏里组主要为潮坪-泻湖相沉积,索瓦组主要为混积陆棚-泻湖-潮坪相沉积,中-晚侏罗世羌塘盆地古水深在下降的总趋势中呈现浅→深→浅→深→浅的升降旋回,盆地沉积中心由东向西迁移,区域构造演化和全球海平面变化共同控制了盆地沉积面貌。     

Chemical variation from biolipids to sedimentary organic matter in modern oceans and its implication to the geobiological evaluation of ancient hydrocarbon source rocks

Understanding the dynamics of organic matter in modern marine water columns greatly favors the geobiological evaluation of hydrocarbon source rocks. Biolipids could make great contribution to petroleum hydrocarbons due to their comparable chemical components and the slightly refractory characteristics of biolipids during the microbial/thermal degradation. A variety of environmental factors such as temperature, CO₂ and salinity could affect the biochemical contents in microorganisms. As a result, microorganisms living in a changing environmental condition might have a different contribution to the petroleum formation. Organic carbon flux is shown to bear a positive correlation with the primary productivity only within a certain range of biomass volumes in a specific biohabitat. Furthermore, organic matter is degraded much quickly in a water column with oxic conditions. Therefore, the anoxic condition, along with the enhanced biological productivity, would be one of the significant factors in the formation of high-quality hydrocarbon source rocks. The formation of biofilms and microbial mats favors the preservation of sedimentary organic matter by decreasing the degradation rate of organic matter. Identification of biofilms and microbial mats in sedimentary rocks will thus greatly help to understand the depositional processes of organic matter finally preserved in hydrocarbon source rocks. __________ Translated from Earth Science—Journal of China University of Geosciences, 2007, 32(6): 748–754 [译自: 地球科学—中国地质大学学报     

Simulation of diagenesis and permeability variation in two-dimensional rock structure

A model is suggested to simulate the physical aspect of diagenesis in porous rocks. A bidisperse ballistic deposition model with relaxation of deposited grains is used to generate the porous structure. Sedimentation and erosion are allowed to restructure the pore space as a fluid flows through the rock. The effect of this restructuring of the pore space on permeability is studied. The Navier–Stokes equation is solved numerically by the finite difference method to determine the pressure and velocity distributions in the pore space. We find that though deposition is the dominant process in our model of diagenesis, reducing the porosity, the permeability may increase dramatically in some cases. These are when the erosion takes place at a single narrow constriction in the pore channel.     

低渗透油藏储层沉积微相研究--以松辽盆地乾安油田高台子油层Ⅶ砂组为例

针对低渗透油藏储层的特征，以岩心资料和大量的测井，录井数字化资料为基础，应用沉积微相制图软件系统实现了乾安油田高台子油层Ⅶ砂组低渗透储层的沉积微相自动识别，本区储层沉积微相为水下分流河道，席状砂、远砂坝和水下扇等类型，绘制出VII砂组3个小层的平面沉积微相图，沉积微相的研究对本区主力油层及剩余油分布具有指导意义。