Links between bulk sediment particle size and magnetic grain‐size: general observations and implications for Chinese loess studies     

FRANK OLDFIELD  QINGZHEN HAO  JAN BLOEMENDAL  ZOË GIBBS‐EGGAR  SHIVA PATIL  ZHENGTANG GUO 《Sedimentology》2009,56(7):2091-2106

Using a combination of particle size analysis, magnetic measurements, scanning electron microscopy and transmission electron microscopy imaging, this study shows that in a wide range of depositional environments, there is a strong link between particle size classes and magnetic response, especially below the upper limit of stable single domain magnetic behaviour. Ferrimagnetic grain assemblages dominated by stable single domain magnetosomes regularly have peak susceptibility and remanence values in coarser grades than do those containing finer‐grained, viscous and superparamagnetic secondary magnetic minerals formed during pedogenesis. This effect is despite the fact that there is a one to two orders of magnitude size difference between the particle size boundaries (at 1 or 2 μm) and key domain state transitions (mostly below 0·05 μm). The implications of these results are explored using samples spanning 22 Myr of loess accumulation on the Chinese Loess Plateau. The results from the loess sections, complemented by data from low‐temperature magnetic experiments, show that there are subtle distinctions in mean ferrimagnetic grain‐size between the Pleistocene and Miocene parts of the record, thus allowing more refined rock magnetic interpretations of the fine‐grained ferrimagnetic mineral assemblages arising from the effects of weathering, pedogenesis and possibly diagenesis in the sections studied.  相似文献   

Accumulation Mechanisms and Evolution History of the Giant Puguang Gas Field, Sichuan Basin, China     

HAO Fang  GUO Tonglou  DU Chunguo  ZOU Huayao  CAI Xunyu  ZHU Yangming  LI Pingping  WANG Chunwu  ZHANG Yuanchun 《《地质学报》英文版》2009,83(1)

Solid bitumens were found throughout the carbonate reservoirs in the Puguang gas field,the largest gas field SO far found in marine carbonates in China,confirming that the Puguang gas field evolved from a paleo-oil reservoir.The fluid conduit system at the time of intensive oil accumulation in the field Was reconstructed,and petroleum migration pathways were modeled using a 3-D model and traced by geochemical parameters.The forward modeling and inversion tracing coincided with each other and both indicated that oils accumulated in the Puguang-Dongyuezhai structure originated from a generative kitchen to the northwest of the Puguang gas field.The deposition of organic-rich Upper Permian source rocks dominated by sapropelic organic matter in the Northeast Sichuan Basin, the development of fluid conduit system that was vertically near-source rock and laterally near-generative kitchen,and the focusing of oils originated from a large area of the generative kitchen,were the three requirements for the formation of the giant paleo-oil reservoir from which the giant Puguang gas field evolved.The Puguang gas field had experienced a three-stage evolution.The post-accumulation processes,especially the organic-inorganic interaction in the hydrocarbon-water-rock system,had not only profoundly altered the composition and characteristics of the petroleum fluids,but also obviously changed the physicochemical conditions in the reservoir and resulted in complicated precipitation and solution of carbonate minerals.  相似文献   

Biodiversity and Sequence of the Middle Triassic Panxian Marine Reptile Fauna, Guizhou Province, China   总被引：2，自引：0，他引：2  

JIANG Dayong  Ryosuke MOTANI  HAO Weicheng  Olivier RIEPPEL  SUN Yuanlin  Andrea TINTORI  SUN Zuoyu  Lars SCHMITZ 《《地质学报》英文版》2009,83(3):451-459

Abstract: The Middle Triassic Panxian fauna is a physical marker and representative record of the rapid recovery of the Triassic marine ecosystem following the Early Triassic stagnant stage after the end-Permian mass extinction. Ten marine reptile taxa have been found from the 1.82–2.10 m-thick fossiliferous level in the Upper Member of the Guanling Formation, which can be subdivided into three marine reptile beds through the analysis on the stratigraphic distributions of fossil reptiles. The Lower Reptile Bed yields the sauropterygians Placodus inexpectatus Jiang et al., 2008 and Lariosaurus hongguoensis Jiang et al., 2006, the ichthyopterygians Xinminosaurus catactes Jiang et al., 2008 and Phalarodon cf. Phalarodon fraasi Merriam, 1910, associated with Mixosaurus panxianensis Jiang et al., 2006, representing a stage of predominance of durophagous taxa. In this bed, the large complete skeletons may reach up to 2.3 m in length, and lithofacies and chemostratigraphic analyses indicate a relatively deep carbonate platform with an oxic water environment near the bottom, as well as a rising sea level. The Middle Reptile Bed yields the sauropterygian Nothosaurus yangjuanensis Jiang et al., 2006 and the archosaur Qianosuchus mixtus Li et al., 2006, associated with Mixosaurus panxianensis Jiang et al., 2006. The fossils in this bed are characterized by its pincering dentition and large overall body size, with the largest possibly exceeding 3 m in length. This bed might represent a time of deepest basin with relatively anoxic condition near the bottom. The Upper Reptile Bed yields the sauropterygians Wumengosaurus delicatomandibularis Jiang et al., 2008, Keichousaurus sp., the protorosaur Dinocephalosaurus orientalis Li, 2003, and the ichthyopterygian Mixosaurus panxianensis Jiang et al., 2006. In this bed, reptilian taxa characterized by suction feeding appeared, and most are less than 1 m long. This bed corresponds to a period of decreasing water depth.  相似文献   

长江中下游成矿带深部找矿思路探讨   总被引：4，自引：0，他引：4       下载免费PDF全文

真允庆  丁梅花  戴宝章  袁杰  花林宝  李忠华  赵理芳  郝红蕾  陈国衡 《地质找矿论丛》2009,24(3):179-188

长江中下游成矿带的探明资源已开采殆尽,深部找矿（-500--2000m）应是当务之急。根据勘查与开采资料的综合研究,该区的控矿条件可概括为：岩石圈减薄事件是成矿作用的重要前提,燕山期强烈的构造-岩浆活动是区域成矿的主要关键,地表断裂构造样式是深部构造的响应,前陆盆地沉积建造是成矿作用的优越围岩条件,铁、铜矿床的岩浆岩蚀变特点明显不同,埃达克质岩可视为找铜矿床的间接标志。对于今后深部找矿提出4个思路：①火山岩盆地下部的深部找矿思路;②目标地层的深部找矿思路;③复合类型矿床的深部找矿思路;④接触带“多台阶”的深部找矿思路。  相似文献   

濮阳台电磁波观测的干扰因素分析     

李桂清  厉天琴  彭淑丽  郝春花  李华平 《高原地震》2004,16(3):69-70,65

濮阳台电磁波异常与地震活动有很好的对应关系。但电磁波观测存在诸多干扰因素的影响,对干扰因素及其影响进行了分析研究。  相似文献   

地幔纬向正常密度函数   总被引：7，自引：0，他引：7  

郝晓光  刘根友 《测绘学报》2004,33(2):105-109

继"地球纬向正常密度假说"和"板块运动纬向重力模式"的提出之后,以参数椭球为工具,应用求解"地球纬向正常密度函数"的数学方法,在假设地核为匀质椭球和地壳并入地幔的前提下,初步求解出满足极点与赤道重力条件的"地幔纬向正常密度函数",从而使得"地幔纬向密度异常"的提法在理论上获得了依据.  相似文献   

一种基于小波系数特征的遥感图像融合算法   总被引：20，自引：2，他引：18  

刘哲  郝重阳  冯伟  刘晓翔  樊养余 《测绘学报》2004,33(1):53-57

多光谱图像和全色图像是目前卫星遥感领域最常见的传感器图像.为了更充分地发挥这两类遥感图像数据的价值,人们利用两类数据的互补性,将多传感器融合技术引进了遥感图像处理领域.在IHS彩色空间变换和小波多分辨率分析的基础上,利用图像高频小波系数的多个特征来定义特征量积,并利用特征量积作为依据提出了一种图像融合新算法.通过一组多光谱图像和全色图像数据进行融合仿真试验,并将该算法与IHS,HPF等算法和归一化矩算法作了比较.证明该方法能在保留多光谱图像光谱信息的基础上,有效地提高多光谱图像的空间分辨率.  相似文献   

青海都兰地区前泥盆纪古陆块的物质组成和重大地质事件   总被引：5，自引：0，他引：5  

郝国杰  陆松年  辛后田  王惠初 《吉林大学学报(地球科学版)》2004,34(4):495-501,516

通过对青海都兰地区前泥盆纪地块的地质、地球化学和同位素年代学研究,将其由北向南划分为欧龙布鲁克微陆块、沙柳河超高压碰撞带和柴达木陆块三个构造单元.基本查明了欧龙布鲁克古陆块主要由德令哈片麻岩、莫河片麻岩、达肯大坂岩群、万洞沟群和全吉群组成,柴达木盆地北缘高压碰撞带主要为中新元古代沙柳河岩群、花岗闪长质片麻岩、英云闪长质片麻岩、钾长花岗片麻岩、榴辉岩、滩间山群和蛇绿岩,柴达木古陆块主要由古元古代金水口岩群和夕线堇青花岗片麻岩组成.详细厘定了本区前泥盆纪重要地质事件,特别是与Rodinia超大陆有关的汇聚与裂解事件.同时,利用先进的同位素地质年代学手段,确定了本区重要地质事件的地质时代和序列,为研究我国中-新元古代古陆块汇聚与裂解关系,以及它们在整个超大陆中的位置提供了证据.  相似文献   

祁连山冻土区多组分气体水合物形成过程实验研究     

孟庆国  刘昌岭  李承峰  郝锡荦 《海洋地质前沿》2022,38(1):72-79

祁连山冻土区天然气水合物气体组成复杂,储层裂隙发育,研究其形成过程对准确理解该区域天然气水合物的形成机制具有重要意义.基于祁连山冻土区水合物的气体组成配置了多组分气体,并对其在纯水、水合物矿区水及冻土岩芯介质体系中的水合过程进行了实验观测,获得了不同条件下多组分气体水合物的诱导时间及聚集形态特征,探讨了不同反应介质(水...  相似文献   

涌水坑道钻孔岩心上升系数ξ定义及其实践意义          下载免费PDF全文

郝海洋 《探矿工程》2019,46(6):26-30

坑道钻孔内涌水给常规小口径取心钻探带来了极大的施工难题。水银洞金矿Ia矿体地下水丰富,坑道钻探施工中,发现孔底岩心可以从孔口冲出。由此提出了坑道涌水钻孔岩心上升系数ξ,其物理意义是岩心在孔底水压和浮力的作用下,克服重力以及与钻杆内壁摩擦力而自动上升的能力,并结合钻孔实际参数,讨论了ξ的实践意义。当ξ≥1时,理论上孔底岩心可以随孔内涌出水从孔内冲出;当ξ＜1时,孔底岩心则不能被冲出,只能依靠起大钻取出。通过计算矿层的岩心上升系数,结合实际地层的完整性情况,可以帮助钻探人员控制合适的进尺后割心,使ξ≥1,从而让钻孔内岩心自动从孔底排出。岩心上升系数,可以为提高地表和坑道高压涌水钻孔钻进效率提供理论指导,具有一定的实践意义。  相似文献