Geothermal structure of the eastern Pontides orogenic belt： Implications oceanic lithosphere Black Sea basin and the eastern for subduction polarity of Tethys

The numerical results of thermal modeling studies indicate that the lithosphere is cold and strong beneath the Black Sea basin.The thermal lithospheric thickness increases southward from the eastern Pontides orogenic belt（49.4 km） to Black Sea basin（152.2 km）.The Moho temperature increases from 367℃in the trench to 978℃in the arc region.The heat flow values for the Moho surface change between 16.4 mW m^-2 in the Black Sea basin and 56.9 mW m^-2 in the eastern Pontides orogenic belt. Along the southern Black Sea coast,the trench region has a relatively low geothermal potential with respect to the arc and back-arc region.The numerical studies support the existence of southward subduction beneath the Pontides during the late Mesozoic-Cenozoic.     

塔里木盆地东部南华系-寒武系黑色岩系地球化学特征及形成与分布

近年来,随着油气勘探向深层-超深层领域拓展,古老层位的烃源岩逐渐成为研究热点。塔里木盆地周缘广泛出露的前寒武地层为古老烃源岩及其发育背景研究提供了基础。本文主要介绍了塔东地区南华系、震旦系和寒武系三套烃源岩,通过对库鲁克塔格地区野外露头及岩芯资料的综合分析,采用有机地球化学和无机地球化学手段对烃源岩质量以及烃源岩发育环境进行了评价,认为南华系特瑞艾肯组、震旦系水泉组、寒武系西大山组为主要烃源岩发育层位。特瑞艾肯组烃源岩TOC分布在0.22%~2.80%,平均值1.65%,Ro平均值为1.28%~1.60%;水泉组烃源岩TOC分布在0.22%~0.79%,平均值为0.49%;Ro分布在1.37%~1.93%之间（均值1.72%）;西大山组烃源岩TOC分布在0.15%~1.45%,平均值0.47%。结合地震资料对裂陷结构进行追踪,初步对塔里木盆地东部三套烃源岩的分布范围进行了限定。针对塔里木盆地新元古代盆地演化背景,运用C、O、Sr同位素及微量元素等,对三套黑色岩系形成环境与发育机制进行分析;并对库鲁克塔格地区的冰期事件进行了的限定,认为塔东地区南华-寒武纪至少发生过三期冰期事件,塔东地区冰碛岩地层的划分可以为全球前寒武地层对比提供依据。     

云南曲靖地区下寒武统筇竹寺组页岩气成藏地质条件及有利区预测

基于野外地质调查、岩心观测、地球化学分析、含气量现场解吸等技术手段,深入分析了云南曲靖地区下寒武统筇竹寺组页岩气形成与富集条件。研究认为该区筇竹寺组沉积期为浅水陆棚环境,黑色泥页岩厚度237~363 m,成熟度较高,平均R_o为3.06%,TOC多数大于2.0%;页岩中石英含量平均为53.18%,碳酸盐矿物含量平均为18.82%,储集空间以泥页岩微裂缝、粒间孔、粒内孔和有机孔为主;区域具有较好的页岩气勘探潜力。根据多口钻井现场解吸气量较低的特征,推断保存条件是曲靖地区页岩气富集的关键,马龙为页岩气勘探远景区。     

页岩储层吸附机理及其影响因素研究现状

页岩气是以游离、吸附和溶解状态赋存于暗色泥页岩中的天然气,其吸附态是页岩气的主要赋存状态之一。据统计北美页岩吸附气含量可能至少占页岩气总量的40%,页岩吸附气含量是预测页岩储层产能的关键参数之一。页岩气吸附机理和影响因素的论述,得出：目前对页岩热成熟度、矿物成分和深度等因素研究相对薄弱。国内大多研究还停留在地质资料的宏观对比上,对于页岩气吸附的微观机理研究也还相对薄弱,通过对应加强研究并建立适合我国页岩气地质储量的评估标准,指导页岩气勘探开发。     

Process of Diagenetic System in Shale and Its Restrict on Occurrence of SiO2: A Case Study of the Longmaxi Formation in the Southeast District of Chongqing

The occurrence of SiO₂ has important significance for the development of shale gas, and its genetic mechanism is closely associated with the diagenetic system. Based on the data from field outcrops and drilling cores, we systematically studied the main controlling factors of diagenetic system, the diagenetic process model and its influences on the SiO₂ occurrence of shale in Longmaxi Formation, by means of X-ray diffraction analysis, cathode luminescence, scanning electron microscope, energy spectrum analysis and other research methods. The results show that the process of diagenetic system of shale in Longmaxi Formation is quite complicated and the diagenetic phenomenon is rich. The diagenetic control factors were greatly influenced by deposition mechanism in the early stage, and restricted by the diagenetic mechanism in the middle and late stage, while they were mainly affected by the tectonic mechanism in the late stage. The diagenesis system had apparent phase characteristics influence by tectonic movement, especially for Himalayan stage. During this period, shale formation were greatly uplifted, which not only promoted the connectivity of shale and the outside system, and made dissolution and micro cracks become more developed, but also changed reservoir physical property, hydrocarbon generation and preservation conditions of hydrocarbon obviously. Generally, the different chemical fluids restricted the origin of siliceous in different evolution stages of diagenetic. The occurrence of SiO₂ was mainly composed of continental quartz and opal in the early stage and slowly began to increase typomorphic quartz, while the medium-coarse grained quartz began to develop in the quartz veins after tectonic movements.     

General polytropic spheres as gravitational lenses

We propose hydrostatic polytropic spheres governed by the Lane-Emden equation (LEE) of index $n$ as a novel set of physical models for axially averaged gravitational lenses anywhere in the Universe, alternative to the familiar singular isothermal sphere (SIS) and the Navarro–Frenk–White (NFW) profile, as such general polytropic spheres are conceptually simple, versatile in representing a series of equations of state, and able to address both the inner core and cusp features. As LEE is nonlinear, there exist several distinct classes of LEE solutions to serve as physical lens models. With a few scaling parameters, the complete problem can be readily reconstructed with full physical dimensions. A given mass density profile satisfying LEE produces lensing effects that are solely determined by a dimensionless parameter $q$ which contains geometric and kinematic information about the source-lens-observer system. The lens mapping and tangential shear or distortion profile are derived, first analytically for special cases and then asymptotically at the outskirts or near the edge of the lens. Numerical procedures for calculating full lensing profiles of a general lens are developed. Our results include the analytical “singular polytropic sphere” (SPS) profile which generalizes the SIS model and may outperform the latter in modeling dark matter halos among others. We further point out that dynamic models of general polytropic spheres in self-similar evolution can serve as several broad classes of gravitational lenses and produce time-dependent lensing effects slow or fast depending on the pertinent time scales. Astrophysical sources that can be lensed include electromagnetic wave sources in the entire frequency band, gravitational wave sources in the entire frequency band, gravitons even possibly with finite masses, neutrino sources of three different types, neutron sources, and ultra high energy cosmic rays (UHECRs) of electrically charged particles which can also interact with magnetic fields. We discuss and elabrate applications to dark matter halos, hypermassive black holes and supermassive black holes in the entire Universe including the early Universe, magnetized supermassive stars, static and dynamically evolving spherical and cylindrical lenses in contexts of astrophysics and cosmology.     

黑海西北部多瑙河峡谷北侧陆坡沉积特征及其与古气候的关系

【研究目的】在末次冰期，全球气候变化以千年尺度的快速、大幅度温度波动旋回为特征，这种波动变化在两极冰芯、深海沉积、中国黄土和洞穴石笋等诸多地质样品中均有记录。黑海位于北大西洋与东亚季风区过渡带，具有极有代表性的沉积记录。本文旨在通过对黑海沉积序列的研究，建立起其区域环境变化与北大西洋及东亚季风气候域气候变化的联系。【研究方法】研究对取自黑海西北部罗马尼亚陆坡区多瑙河峡谷北侧GAS-CS12钻孔的长22.0 m的岩芯样品，进行了粒度、矿物成分、主量元素、有机碳、总氮及碳氮同位素等分析。【研究结果】揭示出该段岩芯沉积于末次冰期中后期“Neoeuxine”湖相阶段，可划分为5个沉积单元，对应于北大西洋H4、H3、H1气候变化事件、末次冰盛期（LGM）及Bolling-Allerod气候变暖事件。【结论】建立起了其沉积序列及区域环境变化与北大西洋及东亚季风气候域气候变化的联系，印证了末次冰期千年尺度的气候变化事件在北大西洋、东亚季风区及两者过渡带上具有高度的一致性。创新点：建立了黑海西北沉积序列与区域环境变化的关系；补充了北大西洋与东亚季风区两者过渡带上气候波动事件的可靠时标。