鄂尔多斯盆地北部塔巴庙地区上古生界低压力异常及其与产气性的关系   总被引：2，自引：4，他引：2  

李仲东  过敏  李良  惠宽洋  吴永平 《矿物岩石》2006,26(4):48-53

通过对鄂尔多斯盆地北部塔巴庙地区上古生界地层压力的分布规律、压力历史恢复及其与产气性关系的详细分析,认为上古生界气藏现今属异常低压-常压气藏,各气藏及同一气层的不同区域多为不同的压力系统,气藏横向连通范围有限,与阿尔伯达埃尔姆沃斯地区典型的的深盆气藏有较大的区别;上古生界烃源岩流体压力的演化历史恢复结果及平衡深度法计算证实上古生界泥岩在最大埋深时(早白垩世末)古压力系数达1.46~1.62;现今上古生界储层的异常低压是由历史中的古高压演化而成的,目前塔巴庙地区上古生界为一个高低压相间共存的复杂压力系统;区域压力封盖层——上石盒子组控制了上古生界天然气成藏,目前发现的天然气在纵向上集中分布于下石盒子组、山西组及太原组;上古生界气层压力与气层分布、无阻流量、物性、气藏流体特征有较密切的关系,相对高压力的盒3段、盒2段、太原组为较有利层段,92%的高产气井分布在压力系数大于0.95的区域内,地层压力较低的山1段产气性较差。研究资料显示盒3、2段有明显的富集成藏过程。盒3、2段为下生上储富集型气藏,太2段表现为自生自储近距离聚集型气藏。  相似文献   

新疆库鲁克塔格地区早寒武世硅质岩地球化学特征及其意义   总被引：17，自引：0，他引：17  

杨瑞东  张传林  罗新荣  田敬全  包亚范  宋果奇 《地质学报》2006,80(4):598-605

新疆库鲁克塔格地区寒武系底部硅质岩发育,主要分布于西山布拉克组和西大山组中,厚度达到120m,发育有火山岩-硅质岩,硅质岩夹黑色页岩组合。通过对兴地大坂穷木库杜克剖面硅质岩的系统地球化学研究,硅质岩常量元素Al、Fe、Mn在Al-Fe-Mn三元图上投影落入热水沉积域中。西山布拉克组底部硅质岩富集As、Sb、Sr、Ba、U元素,Th/U值偏低,为0.758,往上逐渐增大,到西大山组硅质岩Th/U值达到8.448。寒武系底部西山布拉克组底部硅质岩具有稀土总量∑REE显著偏低(小于10×10-6)、LREE/HREE值偏低、Ce负异常显著、低的Ce/Ce值(小于0.8)、(La/Ce)N值(1.0~2.89)、Eu/Eu值(≥1)较大、(La/Lu)N值(3.63~6.98)较小等特征,说明有强烈的热水沉积作用。往上到西大山组硅质岩则具有稀土总量∑REE较高(大于10×10-6)、LREE/HREE值较高、Ce负异常明显、Ce/Ce值较大(0.8~1.29)、(La/Ce)N值变化不明显、Eu/Eu值较低(0.5~0.8)、(La/Lu)N值大(平均大于10)等特征,说明热水沉积作用减弱,但仍属热水沉积特征。硅质岩δ30Si和δ18O同位素分析表明,西山布拉克组和西大山组硅质岩为典型的热水成因硅质岩。硅质岩氧同位素测温表明,从下往上热水沉积硅质岩形成温度降低。西大山组底部硅质岩形成温度较高,达到80℃以上,随后温度逐渐降低,西大山组硅质岩形成的温度为69℃左右。新疆库鲁克塔格地区寒武系底部硅质岩地球化学特征表明,在早寒武世早期库鲁克塔格地区地壳发生强烈的拉张裂解作用,这种拉张裂解作用形成火山岩和硅质岩、硅质岩和黑色页岩组合,它们为早寒武世早期Rodinia大陆发生快速裂解作用提供了岩石学和地球化学证据。  相似文献   

黑龙江鸡西早白垩世侧羽叶一新种-城子河侧羽叶 (Pterophyllum chengzihense sp.nov.)   总被引：1，自引：0，他引：1  

刘风香 《世界地质》2006,25(1):1-5

根据产于黑龙江鸡西早白垩世城子河组一种侧羽叶属(Pterophyllum)植物化石的外形特征及表皮构造研究,确认该种属于本内苏铁类(Bennettitales)植物,并有别于其他植物类群。据此,新建一新种—城子河侧羽叶(新种)Pterophyllumchengzihensesp.nov.,并讨论了该新种在研究中国东北地区早白垩世植物化石中的意义。  相似文献   

辽北清原地体上的一个新的特殊岩石地层单位—芦家堡子岩组   总被引：1，自引：1，他引：1  

陈跃军  孙春林  刘跃文  孙罡  王秀萍 《世界地质》2006,25(3):213-220,244

辽宁北部清河镇—吉林南部山城镇一带的一套变质地层最早被称为古元古代辽北“辽河群”,后来又称为早古生代清河镇群、太古宙沙河岩群 寒武纪开原岩群、中新元古代开原岩群等。最新研究证明,这是一套不同大地构造单元内的、不同时代、不同属性的地质体的拼合物。以清河断裂为界,北部属于陆缘活动带,可划分为新元古代西保安岩组、寒武纪佟家屯岩组和晚二叠世尖山子火山岩;南部为华北板块辽北清原地体,除太古代TTG岩系和少量的表壳岩外,还有一套变质石英砂岩大理岩变质火山岩为主的地层,即一个新的特殊岩石地层单位。本文作者提出新命名为古元古代芦家堡子岩组。  相似文献   

SHRIMP zircon U-Pb age and significance of Early Paleozoic volcanic rocks in East Kunlun orogenic belt, Qinghai Province, China   总被引：6，自引：0，他引：6  

ZHU Yunhai  LIN Qixiang  JIA Chunxing & WANG Guocan .Faculty of Earth Science  China University of Geosciences  Wuhan  China  .Regional Geological Survey Academy of Qinghai  Xining  China 《中国科学D辑(英文版)》2006,49(1):88-96

A great deal of practical data in recent years have proved that the East Kunlun orogenic belt and even the China central orogenic belt are complex orogenic belts that underwent polycycle orogenic evolvement[1―7]. Each orogenic cycle has left a compositional print, the multi-period ophiolites[4―6] and various types of tec-tono-magmatic production in the same orogenic belt. There is a suite of shallow metamorphic volcanic rocks in the Nuomuhong area in the east part of the East Kunlun orogen…  相似文献   

Early Cretaceous gabbroic rocks from the Taihang Mountains: Implications for a paleosubduction-related lithospheric mantle beneath the central North China Craton   总被引：20，自引：0，他引：20  

Yuejun Wang  Weiming Fan  Hongfu Zhang  Touping Peng 《Lithos》2006,86(3-4):281-302

SHRIMP zircon U–Pb ages and geochemical and Sr–Nd–Pb isotopic data are presented for the gabbroic intrusive from the southern Taihang Mountains to characterize the nature of the Mesozoic lithospheric mantle beneath the central North China Craton (NCC). The gabbroic rocks emplaced at 125 Ma and are composed of plagioclase (40–50%), amphibole (20–30%), clinopyroxene (10–15%), olivine (5–10%) and biotite (5–7%). Olivines have high MgO (Fo = 78–85) and NiO content. Clinopyroxenes are high in MgO and CaO with the dominant ones having the formula of En_42–46Wo_41–50Fs_8–13. Plagioclases are dominantly andesine–labradorite (An = 46–78%) and have normal zonation from bytownite in the core to andesine in the rim. Amphiboles are mainly magnesio and actinolitic hornblende, distinct from those in the Precambrian high-pressure granulites of the NCC. These gabbroic rocks are characterized by high MgO (9.0–11.04%) and SiO₂ (52.66–55.52%), and low Al₂O₃, FeOt and TiO₂, and could be classified as high-mg basaltic andesites. They are enriched in LILEs and LREEs, depleted in HFSEs and HREEs, and exhibit (⁸⁷Sr/⁸⁶Sr)_i = 0.70492–0.70539, ε_Nd(t) = − 12.47–15.07, (²⁰⁶Pb/²⁰⁴Pb)_i = 16.63–17.10, Δ8/4 = 70.1–107.2 and Δ7/4 = − 2.1 to − 9.4, i.e., an EMI-like isotopic signatures. Such geochemical features indicate that these early Cretaceous gabbroic rocks were originated from a refractory pyroxenitic veined-plus-peridotite source previously modified by an SiO₂-rich melt that may have been derived from Paleoproterozoic subducted crustal materials. Late Mesozoic lithospheric extension might have induced the melting of the metasomatised lithospheric mantle in response to the upwelling of the asthenosphere to generate these gabbroic rocks in the southern Taihang Mountains.  相似文献   

Paleozoic rocks in infrastructure of the metamorphic core, the Greater Caucasus Main Range zone     

M. L. Somin  A. B. Kotov  E. B. Sal’nikova  O. A. Levchenkov  A. N. Pis’mennyi  S. Z. Yakovleva 《Stratigraphy and Geological Correlation》2006,14(5):475-485

Granitoid orthogneisses and migmatites are widespread in the lower, deeply metamorphosed gneiss-migmatite complex of the pre-Alpine basement (infrastructure) exposed within northern part of the Greater Caucasus Main Range zone. Like the other rocks of the complex, they have been traditionally attributed to the Proterozoic, but the U-Pb dating revealed the Late Paleozoic age of migmatites and Devonian age of orthogneiss protolith. Bodies of blastomylonitic apogranite gneisses, which are confined to boundary between gneiss-migmatite complex and overlying Makera Complex of supracrustal rocks, turned out to be of the Late Paleozoic age as well. The dating results suggest synchronism and, apparently, genetic interrelations between the high-T/low-P metamorphism and granite formation in the Main Range zone of the Greater Caucasus.  相似文献   

Hermann Wilhelm Abich im Kaukasus: Zum zweihundertsten Geburtstag     

Ilse Seibold  Eugen Seibold 《International Journal of Earth Sciences》2006,95(6):1087-1100

Hermann Abich was born in 1806 in Berlin and died in 1886 in Graz. He grew up in a wealthy family which had friendly relations with famous scientists like Alexander von Humboldt, Leopold von Buch or Carl Ritter. After his studies in Heidelberg and Berlin he turned to extended fieldwork at the volcanoes of Italy. In 1833–1834 he published excellent petrological/chemical results and got soon a good scientific reputation. Thus he was nominated as Professor for Geology and Mineralogy of the prestigious Russian University in Dorpat (now Tartu, Esthonia) in 1842. In 1844 he was sent to Armenia by the Russian authorities. For the next three decades his fieldwork with about 190 publications was concentrated on the Great and Lesser Caucasus. This was a period of Russian expansion to the South with long-lasting regional fights. But he enjoyed the support of powerful governors. He was an indefatigable and enthusiastic explorer and a precise observer and designer. His interests covered many fields: morphology, glaciology, structural geology, volcanology with Thermal Springs, mineral resources from hydrocarbons, coal, salt to ores, stratigraphy and paleontology as a base for geological maps. But he also gave advice for practical problems, and he was active in meteorology, botany and archaeology. Alltogether he became “the Father of Caucasus Geology”. The following sketch stresses only on three aspects of his activities. He was one of the first pioneers in hydrocarbon exploration, especially around the anticlines with the mud volcanoes near Baku. In many respects, however, his fundamental ideas were erronous. He explained the structure of the Great Caucasus by the traditional theories of Leopold von Buch and Elie de Beaumont. The Caucasus anticline “was elevated by forces acting from beneath”. Following them he tried to discover regularities in the strike of mountain chains. Similarily he treated volcanism like Alexander von Humboldt and Leopold von Buch with their two groups of phenomena: voluminous, mostly basaltic “elevation craters” versus isolated, mostly trachytic and relatively small cones of “true volcanoes”. In spite of the isolation of the Caucasus region he had cultivated continuously contacts with leading geologists in Europe and was honoured by many institutions. He left Russia in 1876 for Vienna planning to write there the final monograph volumes about his investigations but he died before he could complete them.  相似文献   

Radiometric ages of the Fire Clay tonstein [Pennsylvanian (Upper Carboniferous), Westphalian, Duckmantian]: A comparison of U–Pb zircon single-crystal ages and Ar/Ar sanidine single-crystal plateau ages     

Paul C. Lyons  T.E. Krogh  Y.Y. Kwok  Donald W. Davis  William F. Outerbridge  Howard T. Evans  Jr.   《International Journal of Coal Geology》2006,67(4):259-266

The Fire Clay tonstein [Pennsylvanian (Upper Carboniferous), Westphalian Series, Duckmantian Stage]–a kaolinized, volcanic-ash deposit occurring in Kentucky, West Virginia, Tennessee, and Virginia–is the most widespread bed in the Middle Pennsylvanian of the central Appalachian basin, USA. A concordant single-crystal U–Pb zircon datum for this tonstein gives a ²⁰⁶Pb/²³⁸U age of 314.6 ± 0.9 Ma (2σ). This age is in approximate agreement with a mean sanidine plateau age of 311.5 ± 1.3 Ma (1σ, n = 11) for the Fire Clay tonstein. The difference between the two ages may be due to bias between the ⁴⁰K and ²³⁸U decay constants and other factors. The age of the Fire Clay tonstein has important implications for Duckmantian Stage (Westphalian Series) sedimentation rates, correlations with the Westphalian Series of Europe, Middle Pennsylvanian volcanic events, and the late Paleozoic time scale.  相似文献   

Age and petrogenesis of plagiogranite intrusions in the Ankara mélange, central Turkey     

Yildirim  Dilek  Peter  Thy 《Island Arc》2006,15(1):44-57

Abstract   The Ankara mélange within the Izmir–Ankara–Erzincan suture zone in north-central Turkey includes ophiolitic fragments that represent the remnants of an oceanic basement evolved between the Sakarya and Kirsehir continental blocks in the early Mesozoic. The serpentinized upper mantle peridotites and lower crustal rocks in these ophiolites are cross-cut by dolerite and plagiogranite dykes, which show mutually intrusive relations indicating their synchronous emplacement into the pre-existing oceanic lithosphere. Zircon dating (U–Pb) of a plagiogranite dyke has revealed a concordia age of ∼179 ± 15 Ma that is interpreted here as the crystallization age of this differentiated rock. A fourth fraction of the zircon separates from this rock has also shown an inherited component greater than 1.7 Ga, possibly derived from the Precambrian core of the Rhodope–Strandja Metamorphic Massif in the Balkan Peninsula. Models for plagiogranite formation were tested and it is concluded that a high extent (<70%) of anhydrous or water-undersaturated, early amphibole-free fractionation of a basaltic melt source may have readily produced the observed REE concentrations for the Ankara mélange plagiogranites. The trace element abundances and other geochemical features of the coeval dolerite dykes are similar to those of the plagiogranites, suggesting a common melt source. The Ta–Nb patterns shown by both the plagiogranite and dolerite dykes are typical of arc-related petrogenesis and can be explained by the addition of slab-derived components to a depleted mantle wedge. The Early Jurassic ophiolitic basement and the dyke intrusions were formed in a back-arc setting between the Paleo- and Neo-Tethyan domains in the eastern Mediterranean region. The Izmir–Ankara–Erzincan Sea developed in this back-arc environment and the related suture zone had a diachronous evolutionary history.  相似文献