Static pressure of hot gas: Its effect on the gas disks of galaxies

The static pressure of the hot gas that fills clusters and groups of galaxies can affect significantly the volume density and thickness of the gas disks in galaxies. In combination with the dynamic pressure, the static pressure allows several observed peculiarities of spiral galaxies surrounded by a hot medium to be explained.     

The formation of the Oort cloud in open cluster environments

We study the influence of an open cluster environment on the formation and current structure of the Oort cloud. To do this, we have run 19 different simulations of the formation of the Oort cloud for 4.5 Gyrs. In each simulation, the Solar System spends its first 100 Myrs in a different open cluster environment before transitioning to its current field environment. We find that, compared to forming in the field environment, the inner Oort cloud is preferentially loaded with comets while the Sun resides in the open cluster and that most of this material remains locked in the interior of the cloud for the next 4.4 Gyrs. In addition, the outer Oort cloud trapping efficiencies we observe in our simulations are lower than previous formation models by about a factor of 2, possibly implying an even more massive early planetesimal disk. Furthermore, some of our simulations reproduce the orbits of observed extended scattered disk objects, which may serve as an observational constraint on the Sun's early environment. Depending on the particular open cluster environment, the properties of the inner Oort cloud and extended scattered disk can vary widely. On the other hand, the outer portions of the Oort cloud in each of our simulations are all similar.     

台湾东部海域沉积物波特征及其成因探讨

利用地震剖面对沉积物波的分布、形态和内部结构进行了分析,结合区域地质背景对沉积物来源和成因进行了探讨。识别出的沉积物波域主要位于台东峡谷与陆坡其他峡谷的交汇区,单个波形的波长为0.8～7.2 km,波高为18～75 m左右,呈NE—SW向展布。台东峡谷弯曲段内侧向上坡迁移的沉积物波,其底界发育块体流沉积,内部可细分为下部过渡单元和上部波形单元。弯曲段外侧的沉积物波呈垂向加积的特征,底部无块体流沉积。基于沉积物波的几何形态,估算整个波域的流体厚度在196～356 m之间,流体速度在15～21 cm/s之间。沉积物波的形态特征、内部结构、分布规律以及数值计算表明这些沉积物波为浊流成因。台湾东部海域沉积物波域的发育与台湾西南部的沉积物波域一样,是台湾造山运动的沉积响应。距今3.5 Ma以来花东海脊的形成以及广燠火山岛—绿岛—兰屿火山岛间闸口的抬升和封闭使得沉积物经由卑南溪及海下水道向南输送到绿岛西侧的台东海槽残留弧前盆地时受阻,转而沿台东峡谷及陆坡冲沟体系向东输送入花东海盆。浊流沉积物沿着峡谷/沟谷体系向下坡方向输送的过程中,在峡谷/冲沟的嘴部等地形限制性降低的位置卸载,或在台东峡谷的高弯曲段漫溢出来,从而形成沉积物波域。     

西准萨吾尔山一带吉木乃组地层时代厘定及意义

正"吉木乃组"由新疆地质局区测大队与中国地质科学院地质研究所1974年创建,创名地为吉木乃县哈尔加乌西南萨尔布拉克沟,原称之为萨尔布拉克组。后因名称与柯坪地区奥陶系组名相同,将其更名为吉木乃组,时代置于早石炭世(新疆维吾尔自治区地质矿产局,1993)。新疆地质矿产局地质矿产研究所(1991)将该组时代定为中石炭世(石炭纪三分法)。1998年新疆地矿局第四地质大队在萨吾尔山     

泉子街地区地层可钻性分析及钻头选型

泉子街地区页岩气参数井钻进过程中存在地层可钻性差、研磨性较强,钻进速度慢,单只钻头（牙轮、PDC）进尺少且报废率高等问题。本文通过对泉子街区块岩石可钻性进行分析、评价,可以为该区页岩气勘查钻井施工钻头选型和钻井工程设计优化提供依据,从而达到提高该区钻井施工效率、降低钻井成本、缩短项目工作周期的目的。     

易坍塌地层双管水平定向钻进工艺研究

水平定向钻进技术已被广泛地用于铺设各种管线,具有施工速度快,对地面破坏小,不会影响已有管线的正常使用等优点。但是,在砂卵石和粉细砂类易坍塌地层中,常规的单钻杆水平定向钻进常会出现导向偏差和钻孔坍塌等事故。在已有技术的基础上,开发出了一套双管水平定向钻进系统,包括双回转动力头钻机、内外钻杆、双管导向节。通过现场应用证明了该双管系统具有导向精度高、调整方向灵敏等优点,能克服易坍塌地层带来的导向精度差和钻孔坍塌等难题。     

准噶尔盆地南缘齐古背斜复杂构造建模技术应用

齐古背斜构造复杂,变形强烈,地震资料相对较差,构造样式建立存在多解性。为准确落实该区构造特征,从地质“戴帽”、倾角标定及平衡恢复与几何变形正演等关键技术出发,对齐古背斜进行精细构造解析,确立齐古背斜为早期构造三角楔与晚期冲断褶皱复合叠加的构造样式。该背斜主体部位具分层、分块构造特征,西段以南倾冲断断裂为主,东段以北倾反冲断裂为主。复杂构造建模技术的应用将有助于建立更为合理的构造解释方案,大大降低油气勘探风险。     

Geochemical Characteristics of Wuyang Siliceous Rocks in the Southern Margin of North China Craton and its Constraint on the Formation Environment of BIF of Tieshanmiao Formation

Precambrian banded iron formation(BIF) is one of the most important mineral resources in China, mostly abundant in the North China Craton(NCC) with relatively less common in South China. Since the BIF and siliceous rocks both originated from chemical deposition, the syngenetic BIF and Siliceous rocks can help evaluate their environment of formation. We examine here the mineralogy and geochemistry of siliceous rocks associated with the Tieshanmiao Formation BIF, aiming to decipher the conditions of formation of both BIF and Siliceous rocks in the Wuyang area in the NCC. Analysis of the geochemical characteristics of whole rock shows that the Si O2 content of the siliceous rock ranges from 90.11% to 94.85% and is relatively high overall. Trace element contents of Ba and U are also high, the Ba/Sr ratio ranges from 3.89 to 25.28 and the U/Th ratio ranges from 0.09 to 0.20. Finally, the ΣREE value of rare earth elements ranges from 57.03 ppm to 152.59 ppm, and these indexes all indicate that siliceous rock resulted from hydrothermal deposition. Plots of Al2 O3-Si O2, Si O2/(K2 O+Na2 O)-Mn O2/Ti O2 and Mn-10×(Cu+Co+Ni)-Fe in discrimination diagrams also verify this interpretation. However, both the Mg O content, ranging from 0.16 to 0.32, and the Fe/Ti ratio, ranging from 2.50 to 9.72, suggest that terrigenous material was added during the depositional process. Major and trace element parameters of siliceous rock, such as the Al/(A1+Fe+Mn) ratio(from 0.81 to 0.93), Mn O/Ti O2(from 0.00 to 0.17), Al/(Al+Fe)(from 0.82 to 0.93), Sc/Th ratio(from 0.21 to 0.50), U/Th(from 0.09 to 0.20),(La/Yb)N(from 0.83 to 3.04), and the(La/Ce)N(from 0.01 to 0.02) all imply that the siliceous rock formed in a continental margin. In addition, the Sr/Ba ratio from 0.08 to 0.26, the δCe value from 0.31 to 0.90, and the δEu value from 0.14 to 0.58, all indicate that the siliceous rock was formed at a relatively deeper water depth and under weak hydrodynamic conditions. Siliceous rock and BIF formed in the same geological setting, with the Si O2/(K2 O+Na2 O) ratio of siliceous rock ranging from 28.61 to 47.43, the Si O2/Al2 O3 ratio from 16.53 to 32.37, and the Si O2/Mg O ratio from 287.28 to 592.81, which are all in agreement with chemical deposition associated with volcanic eruptions. The Al2 O3/Ti O2 ratio from 37.82 to 50.30 indicates that the magma source of siliceous rock was of slightly intermediate composition. During the Late Archean in the Wuyang area, the high concentration and high purity Si O2 quickly precipitated from hydrothermal fluids to finally result in the accumulation of siliceous rock in a marginal sea, while the input corresponding to iron formation components was deposited to form iron formation layers, and limestone was only the product formed during the deposition intervals of siliceous rock and iron formations. In this study, the synsedimentary siliceous rocks of BIF act as a new way to provide direct evidence to understand the formation environment of BIF due to its high geochemical stability.     

海域金矿找矿方法研究——以山东省莱州市三山岛北部海域金矿为例

莱州市三山岛北部海域金矿区是世界上第一个查明的海域岩金矿。它通过追索延伸至海域的三山岛断裂,圈定破金找矿靶区。利用海域高精度磁测和浅地层剖面测量配合海上钻探,找到了海域大型金矿。以三山岛海域金矿普查为依托,研究出来的这套海域金矿找矿方法和海上钻探平台,可为今后开展海域金及其它与断裂有关的矿产资源找矿,提供指导和借鉴。     

滇黔北威信凹陷晚二叠世沉积环境与层序地层格架下的聚煤规律浅析

针对滇黔北威信凹陷晚二叠世含煤岩系的“海相-海陆过渡相-陆相”三相变化地带,利用地层剖面上的沉积构造、岩石组合、古生物特征等沉积相判别标志分析研究区的沉积环境及其空间演化,并总结煤质变化规律。在此基础上,通过识别层序与体系域关键界面,建立研究区晚二叠世含煤岩系的层序地层格架,充分讨论研究区厚煤层在层序地层格架下的聚煤规律。研究区自西向东依次为河流冲积平原体系、三角洲-潮坪体系及碳酸盐岩台地体系,成煤环境主要为河流冲积平原中的泛滥盆地河漫沼泽和三角洲-潮坪沉积体系中的上三角洲平原;厚煤层在层序地层中的位置与古地理背景有关,研究区C15,C19煤层形成于最大海泛面附近,C25煤层形成于初始海泛面附近;根据煤质变化规律和煤厚变化特征,在研究区西部的彝良-盐津一带有寻找优质煤炭资源的潜力。