【摘要】 盆地深部由于地球内蕴藏的巨大热源和岩石圈放射性元素蜕变热构成的热能,可通过多种热传导方式释放,如岩浆类热流物质向地壳浅部或近地表上部传递热力形成地热异常和热力作用。鄂尔多斯盆地东部晋西挠褶带热力作用发育具有与华北板块早白垩世发生的重要构造转换和岩石圈减薄事件等背景相关,深部岩浆侵入和热力作用事件的发生可使该区地下深处形成许多隐伏的中深成侵入岩或浅成-喷发相岩体及其伴随的热力构造。早白垩世这次强烈的构造热力变动伴有盆地东翼大面积的抬升隆起、吕梁断隆带的翘倾、离石断裂带和晋西挠褶带及西倾大斜坡的形成。以紫金山碱性杂岩体为代表的岩浆热力作用表现为一个多期形成的岩筒、岩床状碱性侵入体,地球化学特点是富碱、Fe,贫Mg;稀土元素含量高,无Eu异常;表现出岩浆侵入有明显的两组方向和多期多阶段侵入或喷发,可侵入到二叠纪—三叠纪地层中。盆地东部火成岩同位素测年数据统计岩浆-热力作用高峰期在110～150Ma。挑选紫金山碱性杂岩体3件单颗粒锆石样数百粒,进行U-Pb同位素SHRIMP测年,其中17组锆石样年龄在125～132Ma,相当于早白垩世。与华北地区早白垩世较普遍的构造热事件具有一致性。此外,还发现有早期(石炭纪—二叠纪)岩浆热力作用事件。构造演化分析显示多期多阶段热力作用特点。鄂尔多斯盆地东部热力作用对盆地油气煤铀多种能源成矿成藏富集研究与勘探评价具有重要意义。更多还原

【Abstract】 The tremendous heat energy from the deep and the spallation of radioactive elements in the lithosphere, can be released by manifold heat exchange patterns, e.g., magma thermal material transfers thermal action toward the shallow crust and the earth’s surface upside, and forms terrestrial heat abnormality and thermal actions. The thermal actions in Western Shanxi flexural fold belt in the eastern part of Ordos basin developed as: the significant structure transform and lithosphere thinning event of the North China Plate in early Cretaceous, as well as the deep magma intrusion and thermal action, formed many buried mid-deep intrusive rocks and shallow-volcanic eruption rocks as well as concomitant thermal structures in the deep beneath this region. Gone with this strong structure thermal alteration event in early Cretaceous, was large-scale uplift elevation in the eastern limb of the basin, the warping of Lvliangshan block uplift belt, and the form of Li-shi fault belt, Western Shanxi flexural fold belt, and large west-dip slope. Zijinshan alkali complex is the representative of the ascertainment of these thermal structures in the eastern basin, which is multiphase pipe and sill shaped alkali intrusive rocks, and whose geochemistry feathers alkali-rich, K-rich, Fe-rich, Mg-lean, and high content of rare earth elements, without Eu abnormal; and it specially shows: Magma intrusive presenting two visible groups of orientation, multiphase and multistage magma intrusive or volcanic eruption, even intruding into Permian-Triassic systems. Statistic isotope dating of magma-thermal action fastigium of igneous rocks in the eastern basin is among 110～150 Ma. We choose three single-grain zircons, about several hundreds of granules, from Zijinshan alkali complex, and process U-Pb isotopes SHRIMP dating. We gain 17 groups of zircon sample’s dating is among 125～132 Ma, equals early Cretaceous, which definitely ascertains the epoch of this magma thermal action event as early Cretaceous. This result is consistent with the prevalent thermal events in North China area in early Cretaceous. Besides, we also find that there are magma thermal actions during the Carboniferous period and early Permian period. Structure evolvement analyses show multiphase and multistage characteristics of thermal action. The development of thermal actions in the eastern part of Ordos basin has significant effect to the research and forming of oil-gas-coal-uranium multi-energy sources mineralization and oil depositing, as well as the prospecting evaluation in the basin.更多还原