松南长岭断陷无机气成因类型及分布特征

对长岭断陷 CO2气地化分析表明,松南气田多数井的δ^13 Cco2值均大于-8×10^-3,均为无机成因,而东岭气田部分井的δ^13 Cco2值均小于-10×10^-3,属于有机成因。其中无机成因 CO2气体中 R/Ra 值均大于1,表明其无机成因 CO2都属于岩浆幔源成因。对长岭断陷地区钻井气测含量资料综合分析表明,无机成因 CO2气的平面展布特征可划分为：高含 CO2气区（＞90％）,位于中部及东北部,表现有 NNE-NE 向展布的趋势;中高含 CO2气区（70％-90％）,主要位于乾安次凹南部,总体表现为 NNW-近 SN 向展布;中低含 CO2气区（20％-50％）,主要分布于2个地区。红岗地区,以 NNE 向为主。腰英台-达尔罕地区,以近 SN 向为主;南部的低含 CO2气区。垂向上长岭断陷南北2个次凹中的 CO2产出层位显著不同。北部次凹内的产出层位较高,主要以泉头组及其上的青山口组为主。南部的无机 CO2气产出层位以断陷期营城组火山岩为主,少量为登娄库组。     

Continental origin of the Bibong eclogite,southwestern Gyeonggi massif,South Korea

Eclogite is a high-pressure (HP) metamorphic rock that provides important information about the subduction of both continental and oceanic crusts. In this study we present SHRIMP zircon U–Pb isotopic data for a suite of the basement gneisses to investigate the origin of the Proterozoic Bibong eclogite in the Hongseong area, South Korea. Zircon grains from the basement felsic gneisses yielded Paleoproterozoic protolith ages ranging from ca. 2197 to 1880 Ma, and were intruded by syenite at ca. 750 Ma. A HP regional metamorphic event of Triassic age (ca. 255–227 Ma) is recorded in the zircon rims of the country rocks, which is also observed in the zircons from the eclogite. The contacts between the Bibong eclogite and its host rocks support an origin for the Proterozoic protoliths, indicating continental intrusions. The Hongseong area thus preserves evidence for the Triassic collision, indicating a tectonic linkage among the northeast Asian continents.     

洞庭盆地第四纪地质研究现状

从第四纪地层划分、环境、构造活动、近现代洞庭湖构造沉降特征与发展趋势等方面,介绍了洞庭盆地第四纪地质研究现状。前人对洞庭盆地及其周缘地区分别建立了覆盖区和露头区第四纪地层系统,其中覆盖区第四纪下限年龄达3Ma左右。不同研究者对第四纪气候演化和全新世以来的气候与环境演化的认识存在程度不一的差异。对洞庭盆地周缘网纹红土的成因存在水成和风成两种不同观点。对盆地构造活动存在断陷、坳陷、先断陷后坳陷以及其他多种不同观点。对于构造因素和非构造因素对现代湖泊的控制作用存在不同看法。在洞庭湖未来演变趋势方面,由于研究问题的角度不一致,有的认为洞庭湖会逐渐加深扩大,有的认为不久将萎缩消亡。重复水准测量资料对比显示近现代洞庭湖构造沉降速率为3～10mm/a;而沉积速率法计算的晚更新世以来的平均沉降速率为0.06～0.25mm/a,局部为0.62mm/a。最后提出洞庭盆地第四纪地质今后研究的主要方向是气候演化的多指标约束、各次级构造单元构造-沉积特征的详细解剖、覆盖区晚更新世—全新世沉积特征的精细调查以及洞庭湖现代沉降特征的GPS监测等。     

The origin and distribution of natural gas in the frontal uplift area of the Kuqa depression,Tarim Basin

The frontal uplift of the Kuqa depression is an important oil and gas producing area. In this study, the distribution and origin of natural gas were discussed based on natural gas components and isotope data. The main components of natural gas were hydrocarbons with relatively high contents of C2+ component. Most gases were de-rived from terrestrial source rocks, and some came from marine rocks. The contents of non-hydrocarbon gases were high in the central part of the frontal uplift area and low in the two terminals. The distribution of oil composition was similar to that of natural gas, which was mainly controlled by the types of source rocks. Dry coefficient and maturity of natural gas in the frontal uplift were lower than those of gas in the Kelasu tectonic belt of the Kuqa depression, which was mainly affected by the difference of tectonic movements in both areas. In the frontal uplift, the traps were formed in the early stage and could capture the early formed oil and gas, and structural adjustment was slight in later stages, so the oil and gas could be effectively preserved. Multiperiodic oil and gas filling led to the complex distribu-tion of natural gas.     

Xingxueanthus: An Enigmatic Jurassic Seed Plant and Its Implications for the Origin of Angiospermy

Abstract: The origin of angiosperms has been tantalizing botanists for centuries. Despite the efforts of palaeobotanists, most of the pre-Cretaceous angiosperms are regarded either non-convincing or misdated. The applications of SEM and LM (light microscope) enable us to recognize a coalified fossil plant, Xingxueanthus sinensis gen. et sp. nov., from the Haifanggou Formation (Middle Jurassic, >160 Ma) in western Liaoning, China. Xingxueanthus is an “inflorescence” with more than 20 female units spirally arranged. Each female unit is situated in the axil of a bract. The female unit is composed of an ovule-container and a style-like projection at the top. There is a vertical column bearing several ovules in the ovule-container. The general morphology and the internal structure of Xingxueanthus distinguish itself from any known fossil and extant gymnosperms, and its structures are more comparable to those of angiosperms. Xingxueanthus, if taken as a gymnosperm, would represent a new class, demonstrate an evolutionarily advanced status of ovule-protection in gymnosperms never seen before, and provide new insights into the origin of angiospermy. Alternatively, if taken as an angiosperm, together with Schmeissneria, it would increase the diversity of Jurassic angiosperms, which has been underestimated for a long time, and suggest a much earlier origin of angiospermy than currently accepted.     

Geochemistry of Heavy Oil in the T Block, Oriente Basin and its Origin

<正>Exploration and development experience show that there is obvious oil gravity difference between the southern part and northern part of the"M1"reservoir in the Fanny oil field in the slope of the Oriente Basin,Ecuador.The American Petroleum Institute Gravity(API) values of oils in the northern part are higher than the one in the southern part of the Fanny oil field,with the values of 20°and 10.0°-13.0°,respectively.So the primary purpose of this study was to analyze the heavy oil characteristics of biodegradation and the oil-oil correlation according to the biomarker data and theδ~(13)C signature of oil samples from T block.The results of the hydrocarbon gas chromatography fingermark and the inversion attribute characteristics indicated that there are fluid compartments between the"M1"reservoir of Fanny south.Finally,the models of oil-gas accumulation under the control of multiple-activities of complicated fault systems,as well as the origin of heavy oil,are contended.The early stage oils from the western part of the basin were biodegraded heavily in varying degrees in the whole basin,and the later stage oils were derived from the southern part in a large scale and were mature and lighter.Generally,oil mixing is the primary control of net oil properties,such as API gravity in Oriente Basin.We therefore predicted that the API gravity variation of oil pools radically depends on the injection amount of the later stage oil.Because of the shale barrier in the"M1"reservoir of Fanny south,the later stage hydrocarbon could not pass through and contribute to increase the oil API value.     

大港滩海区中浅层油岩地球化学特征及油气来源分析——以唐家河油田为例

通过唐家河油田中浅层各层系原油及滩海区所有层系烃源岩的碳同位素、色谱、色谱-质谱等地球化学分析,选取δ13C、合适的生物标志物参数,即G/C30H、O/C30H、Ts/Tm、ααR C27/C29、ααRC28/C29、C3122S/(S R)、C2920S/(S R)等进行油源综合对比。结果表明,唐家河油田中浅层各层系原油来源于深层沙三段及沙二段烃源岩,而沙一段和东营组的贡献不大。考虑到沙二段烃源岩厚度小,生油能力有限,唐家河油田沙三段烃源岩是最主要的油气来源。     

Origin of Quartz Cement in the Paleogene Sandstone Reservoir of Shahejie Formation, Bohai Bay Basin, China

The precipitation of authigenic quartz plays a significant role to reduce the reservoir characteristics and enhance the stiffness of the rock.The Es₁ sandstone of Shahejie Formation is acting as a significant hydrocarbon producing rock in the Nanpu Sag.Various methods like thin section petrography,cathodoluminescence(CL),scanning electron microscope(SEM,with EDS),and electron microprobe analysis has been used to reveal the origin of quartz cement as well as to evaluate the effect of quartz cement on reservoir quality.The studied sandstone is classified as immature to mature feldspathic litharenite and lithic arkose and consists of quartz,feldspar,rock fragments and micas.Petrographic studies and SEM analysis shows that the authigenic quartz is acting a significant cement that reduces the reservoir quality.Whereas clay minerals(kaolinite and mixed layer illite to smectite)are dominant in the Es₁ sandstone,that can reduce the reservoir quality.SEM,CL and thin section analysis reveal that there are two stages of quartz cement in the studied samples;that are pore filling authigenic cement and quartz overgrowth cement.Fluid inclusion homogenization temperatures shows that stages of quartz cement were developed with continuous process from 70℃ to 130℃.Quartz cements were generally originated from I/S reaction,feldspar dissolution,conversion of rock fragments and pressure solution.Feldspar dissolution(K-feldspar)and kaolinite to illite reaction is an insignificant silica source for the silica cement which is internally precipitated in a close system with diffusion transporting mechanism.Overall,quartz cement significantly enhance the rock strengthen and brittleness effectively as well as it reduce the overall reservoir quality.     

赤水地区上三叠统须家河组源岩特征及天然气成因

细致观测了野外剖面,并进行了相关的室内分析化验,对比研究了赤水地区与四川盆地其他地区上三叠统须家河组烃源岩分布特征、有机质类型及丰度,结合赤水地区须家河组天然气的主要地球化学特征,揭示了赤水地区须家河组的源岩特征,初步探讨了其天然气成因。结果表明,研究区须家河组的天然气主要来源于下伏地层。     

A ∼25 K temperature of formation for the submicron ice grains which formed comets

Following the observations of ice grains in cometary comae and their size distributions, we reexamined experimentally our previous conclusion that the ice grains which agglomerated to form comet nuclei were formed at ∼25 K. The suggestion of a ∼25 K formation temperature was confirmed experimentally. Moreover, we suggest that these ice grains had to be of submicron size.