准西苏13井区石炭系火成岩有效储层物性下限     

宋明水  张学才  周广清  曹海防  李静  孙鲁宁 《地质力学学报》2019,25(6):1075-1081

有效储层物性下限是进行储层有效厚度统计、储层划分和油藏储量估算的重要依据,研究区石炭系火成岩储层岩性较为复杂,岩石种类较多、组分差异性大并且空间分布及内中的多种属性有着极不匀称的变化,当前国内外学者利用物探资料来判断准西石炭系火成岩有效储层物性下限值的相关研究较少。采用分布函数曲线法和物性试油法分别研究并互相验证进而综合判定物性下限值,避免单一方法的随机性。在此基础上,求取研究区不同层段的物性下限值,建立有效储层物性下限值与储层埋藏深度的拟合方程。研究结果表明:研究区储层多为低孔、中低渗储层,中部区域孔渗相对较高,物性较好,向北部和南部物性逐渐变差;研究区石炭系1500~1900 m及1900~2300 m火成岩有效储层孔隙度下限分别为5.09%、4.93%,渗透率下限分别为0.252 mD、0.198 mD;研究区石炭系火成岩有效储层物性下限与储层埋藏深度呈负相关。   相似文献   

岩浆岩相对碱度的意义和算法     

王希渠 《现代地质》1988,2(1):90

本文从酸碱电子理论出发,提出了一种新的岩浆岩碱度参数——相对碱度及其计算方法。岩石或矿物的相对碱度是其中的氧元素丢失电子能力的综合度量。规定硅作为其他阳离子对氧原子屏蔽作用的比较基准,用各金属氧化物与二氧化硅的反应焓变值作为它们相对于二氧化硅对矿物或岩石相对碱度的贡献。综合各氧化物的碱度贡献使得到岩石或矿物的相对碱度值。计算表明,主要造岩标准矿物和各种岩浆岩的相对碱度值顺序与传统用法基本一致。  相似文献   

克拉麦里—塔克札勒—大黑山蛇绿岩建造稀土元素特征   总被引：3，自引：0，他引：3  

李嵩龄  冯新昌  董富荣  李文铅 《新疆地质》1999,(4)

克拉麦里—塔克札勒—大黑山蛇绿岩建造稀土元素含量由变质橄榄岩—堆积橄榄岩—堆积辉长岩—玄武岩有规律增高 ,总体表现为轻稀土弱富集 ,L/H值大多数大于 1,局部有轻稀土亏损的特征。蛇绿岩建造各单元间稀土元素分布模式不尽相同 ,即使是同一单元在不同地段亦有差异 ,反映地幔岩浆的复杂性。基性熔岩稀土元素分布模式既有洋脊玄武岩的平坦曲线 ,又有轻稀土富集型的夏威夷等洋岛玄武岩的特征 ,反映该蛇绿岩带混杂着洋壳残骸和洋岛碎块。由清水—南明水东—塔克札勒基性熔岩稀土元素含量有规律递增 ,分别是球粒陨石的 9.4、15.4、18.9倍 ,反映玄武质岩浆分异程度逐渐增高 ,间接说明该岩带闭合时间由西向东从中泥盆世—晚石炭世末 ,再向东甚至延续至二叠纪  相似文献   

Plutonism in the Variscan Odenwald (Germany): from subduction to collision     

R. Altherr  U. Henes-Klaiber  E. Hegner  M. Satir  C. Langer 《International Journal of Earth Sciences》1999,88(3):422-443

 Latest Devonian to early Carboniferous plutonic rocks from the Odenwald accretionary complex reflect the transition from a subduction to a collisional setting. For ∼362 Ma old gabbroic rocks from the northern tectonometamorphic unit I, initial isotopic compositions (ε_Nd=+3.4 to +3.8;⁸⁷Sr/⁸⁶Sr =0.7035–0.7053;δ¹⁸O=6.8–8.0‰) and chemical signatures (e.g., low Nb/Th, Nb/U, Ce/Pb, Th/U, Rb/Cs) indicate a subduction-related origin by partial melting of a shallow depleted mantle source metasomatized by water-rich, large ion lithophile element-loaded fluids. In the central (unit II) and southern (unit III) Odenwald, syncollisional mafic to felsic granitoids were emplaced in a transtensional setting at approximately 340–335 Ma B.P. Unit II comprises a mafic and a felsic suite that are genetically unrelated. Both suites are intermediate between the medium-K and high-K series and have similar initial Nd and Sr signatures (ε_Nd=0.0 to –2.5;⁸⁷Sr/⁸⁶Sr=0.7044–0.7056) but different oxygen isotopic compositions (δ¹⁸O=7.3–8.7‰ in mafic vs 9.3–9.5‰ in felsic rocks). These characteristics, in conjunction with the chemical signatures, suggest an enriched mantle source for the mafic magmas and a shallow metaluminous crustal source for the felsic magmas. Younger intrusives of unit II have higher Sr/Y, Zr/Y, and Tb/Yb ratios suggesting magma segregation at greater depths. Mafic high-K to shoshonitic intrusives of the southern unit III have initial isotopic compositions (ε_Nd=–1.1 to –1.8;⁸⁷Sr/⁸⁶Sr =0.7054–0.7062;δ¹⁸O=7.2–7.6‰) and chemical characteristics (e.g., high Sr/Y, Zr/Y, Tb/Yb) that are strongly indicative of a deep-seated enriched mantle source. Spatially associated felsic high-K to shoshonitic rocks of unit III may be derived by dehydration melting of garnet-rich metaluminous crustal source rocks or may represent hybrid magmas. Received: 7 December 1998 / Accepted: 27 April 1999  相似文献   

Yanshanian Magma-Tectonic-Metallogenic Belt in East China of Circum-Pacific Domain (Ⅰ):Igneous Rocks and Orogenic Processes     

Deng Jinfu　Mo Xuanxue　Zhao Hailing　LuoZhaohua　Zhao GuochunDepartment of Geology  Mineral Resources  China University of Geosciences  Beijing 《中国地质大学学报(英文版)》1999,10(1)

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Magnetic evidence of a crustal fault affecting a linear laccolith: The Guadiana Fault and the Monchique Alkaline Complex (SW Iberian Peninsula)     

《Journal of Geodynamics》2014

Magnetic anomalies can help reveal the structure of the upper crust in regions with intermediate or basic igneous rocks, and their continuity is essential to determine the position of crustal faults. The southwestern Iberian Peninsula constitutes the foreland of the Betic Cordillera and is characterized by an elongated E-W dipole extending 200 km toward its external zones. The anomaly is related to the outcropping Monchique Alkaline Complex, characterized by rocks of moderate magnetic susceptibility (0.029 SI) intruding into the metapelitic host rock of the South Portuguese Zone. Analysis of aeromagnetic and field magnetic anomalies serves to constrain the geometry of this laccolith. Toward the east, the magnetic dipole has a 60 km long N-S sharp boundary that coincides with the southern part of the Guadiana River. Field magnetic and gravity anomalies confirm the presence of this structure. It is produced by a sharp step in the elongated anomalous body, with an E downthrown block, interpreted as the offset produced by a deep N-S crustal fault—the Guadiana Fault. Therefore, the Guadiana River has three long linear segments near its mouth, locally coinciding with a N-S trending joint set, that support the presence of this major fault. To date, no evidence of this tectonic discontinuity, coinciding with the Spanish-Portuguese border, has been reported. Magnetic research is essential for understanding the structure of wide regions intruded by intermediate and/or basic igneous rocks.  相似文献   

鲁西地区新太古代早期的岩浆活动——泰山岩套英云闪长质片麻岩锆石SHRIMP UPb年龄的证据          下载免费PDF全文

王世进  万渝生  宋志勇  杨恩秀  王伟  董春艳 《山东国土资源》2013,29(4):1-7

泰山岩套主要岩性为英云闪长质片麻岩和条带状英云闪长质片麻岩,出露于鲁西地区泰山—化马湾—蒙山一带。根据新测的锆石SHRIMP U-Pb年龄结果,其岩浆结晶年龄2 729～2 700Ma,变质年龄2 600Ma,其形成时代确定为新太古代早期。该岩套组成古老陆核,是地幔岩浆侵入混入地壳物质形成的。  相似文献   

Subduction-related 200 Ma Talun metagranite,SE Taiwan: an age constraint for palaeo-Pacific plate subduction beneath South China Block during the Mesozoic   总被引：1，自引：0，他引：1  

T. F. Yui  H. T. Chu  K. Suga  C. Y. Lan  S. H. Chung  K. L. Wang 《International Geology Review》2017,59(3):333-346

Various tectonic models have been proposed to account for the widely distributed igneous activities in the southeastern part of the South China Block (SCB) during the Triassic–Jurassic period. One of the major contending debates is on the timing of initiation of the palaeo-Pacific plate subduction under the SCB, due to lack of unequivocal evidence for arc magmatism during the period in this region.

The 191 ± 10 Ma (N = 5, MSWD = 12) calc-alkalic high-K I-type Talun metagranite occurs in the southern Tailuko belt of the Tananao metamorphic complex, Taiwan. In terms of age, this metagranite belongs to the Early Yanshanian igneous activity in the southeastern part of the SCB. However, its geographic position does not accord with the well-known general oceanward younging trend of the Yansnanian igneous rocks. In view of the large age uncertainty reported, this metagranite is redated in this study. Some zircons of this metagranite are high in U content and are metamict. Zircons with low U contents are analysed by SHRIMP yielding a more precise age of 200 ± 2 Ma (N = 10, MSWD = 4). In particular, the εHf(t) of these dated zircons ranges from +4.5 to +12.9. The metagranite mainly consists of quartz, K-feldspar, plagioclase, with minor amounts of garnet, biotite, zircon, apatite, and pyrrhotite. Chlorite and calcite are secondary phases overprinted by the later tectonic event(s). Its initial Sr isotope compositional range is 0.70473–0.70588, and εNd(t), +2.4 to +3.6. The results demonstrate that the genesis of this metagranite could be attributed to the assimilation-fractionation of a depleted mantle-derived basaltic magma, which was most likely related to arc magmatism. The present study therefore offers key evidence that during the Mesozoic, the palaeo-Pacific plate subduction underneath the SCB would have taken place no later than the very early Jurassic.  相似文献   

Interlinking the Hotspot Track in the Arctic and its Implications for Paleo-plate Reconstrution     

LIU Zhonglan  LI Jianghai  LIU Chiheng  LI Weibo  ZHANG Hongwei 《《地质学报》英文版》2017,91(3):822-831

The Siberian–Icelandic hotspot track is the only preserved continental hotspot track. Although the track and its associated age progression between 160 Ma and 60 Ma are not yet well understood, this section of the track is closely linked to the tectonic evolution of Amerasian Basin, the Alpha-Mendeleev Ridge and Baffin Bay. Using paleomagnetic data, volcanic structures and marine geophysical data, the paleogeography of Arctic plates (Eurasian plate, North American Plate, Greenland Plate and Alaska Microplate) was reconstructed and the Siberian–Icelandic hotspot track was interlinked between 160 Ma and 60 Ma. Our results suggested that the Alpha-Mendeleev Ridge could be a part of the hotspot track that formed between 160 Ma and 120 Ma. During this period, the hotspot controlled the tectonic evolution of Baffin Bay and the distribution of mafic rock in Greenland. Throughout the Mesozoic Era, the aforementioned Arctic plates experienced clockwise rotation and migrated northeast towards the North Pacific. The vertical influence from the ancient Icelandic mantle plume broke this balance, slowing down some plates and resulting in the opening of several ocean basins. This process controlled the tectonic evolution of the Arctic.  相似文献   

北黄海盆地某区块火成岩地震识别与预测     

胡小强  万晓明  简晓玲  沈艳杰 《世界地质》2017,36(1):246-254

利用北黄海盆地某区块最新采集处理的三维地震资料,通过钻、测井资料综合分析建立井震关系。使用地震相分析、叠前反演以及多属性综合预测等技术刻画火成岩的形态和空间展布特征,总结本区火成岩在地震剖面上的响应特征及空间变化规律。综合预测结果显示研究区内东部发育有规模巨大的潜山型火成岩,西北部发育有侵入岩体刺穿,其他区域主要发育小规模岩株、岩墙或岩脉状侵入岩。  相似文献