| 华北克拉通西北缘中—晚奥陶世构造体制转换事件的新发现及对找钾的启示 |
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| 引用本文：王振涛,郑绵平.2017.华北克拉通西北缘中—晚奥陶世构造体制转换事件的新发现及对找钾的启示[J].地球学报,38(s1):3-6. |
| DOI：10.3975/cagsb.2017.s1.02 |
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| 基金项目:国家重大基础研究计划“973”课题“鄂尔多斯奥陶纪古陆表海盆成钾条件、机理和后期演化”(编号: 2011CB403001) |
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| 中文摘要:鄂尔多斯盆地作为华北克拉通的一部分, 其研究历史已逾百年, 迄今分别在盆地基底、岩石地层、生物地层、年代地层、层序地层、岩相古地理、构造-沉积耦合关系和石油地质等方面积累了丰硕成果, 研究程度越来越高。同时, 鄂尔多斯盆地作为多种能源重地, 也日益受到工业界的重视。然而, 迄今为止一些基础地质问题仍然悬而未决, 制约了对鄂尔多斯盆地乃至整个华北克拉通的全面认识, 譬如: 鄂尔多斯盆地基底划分、组成、时代和基底顶面起伏特征不清楚, 早古生代鄂尔多斯盆地西缘的构造背景和盆地原型颇具争议, 盆地全区奥陶系地层对比尚未统一, 奥陶纪华北克拉通相对于东冈瓦纳超大陆的古地理配置缺乏足够的约束, 使之成为国际上颇受关注的研究热点。另外一个与海相钾盐找矿有关的科学问题是: 华北克拉通西部奥陶纪陕北盐盆地在中奥陶统马家沟组沉积了巨大规模的石盐, 但仅在马家沟组五段六亚段发现含钾显示和局部薄钾盐层, 迄今并未发现与石盐沉积规模相匹配的大型固体钾盐矿床, 为什么？除了陕北盐盆地及周缘其他次级凹陷可能还存在尚未发现的海相钾盐矿床以外, 是否当时有部分富钾卤水已迁移出陕北盐盆地？为了回答上述科学问题, 对华北克拉通西、南缘若干经典剖面开展了岩石学、地层学、地球化学、沉积学、地球物理学以及锆石年代学等方面的研究, 获得了一些新认识。 |
| 中文关键词:华北板块 钾盐 奥陶纪 冈瓦纳大陆 岩相古地理 |
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| New Identification of the Tectonic Shift Event during the Middle–Late Ordovician in the Northwestern North China Craton and Implication for the New Prospecting Target Area for Potash Deposits |
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| Abstract:As a part of the North China Craton (NCC), the Ordos Basin is located on the western NCC. So far, the study history of the Ordos Basin has been more than one hundred years. And geologists have accumulated fruitful results in its basin basement, lithostratigraphy, biostratigraphy, chronostratigraphy, sequence stratigraphy, lithofacies palaeogeography, tectonic-sedimentary coupling relationship and petroleum geology, respectively. The research degree of the Ordos Basin has been becoming higher and higher. Moreover, the Ordos Basin owing a variety of important energy mineral resource is increasingly brought to the attention of the industrial community. Some basic geological problems, however, are still up in the air, which hamper the comprehensive understanding of the Ordos Basin and even the NCC. These problems including the division, composition, age, top surface of the basement, the early Paleozoic tectonic setting and basin prototype of the west margin of the Ordos Basin, the Ordovician stratigraphic correlation, and the location of the NCC and its history of interaction with the Gondwana supercontinent during the Paleozoic, are controversial. Another scientific problems related to the marine potash prospecting is: a large scale of rock salt deposited in the Middle Ordovician Majiagou Formation in the Northern Shaanxi Salt Basin (NSSB) in the western NCC, but only potash-containing indicators and thin potash seams were found in the O2m56 member of the Majiagou Formation. Up to now, a large scale of solid potash deposit has not been found, why? They may also exist in other secondary depression, which has not yet found, of the NSSB and its peripheral region. In addition, whether there were some potassium-rich brine migrating out of the NSSB? In order to answer the scientific problems above, we conducted comprehensive research of some classic profiles in the southern and western margin of the NCC on petrology, stratigraphy, geochemistry, sedimentology, geophysics and zircon chronology and obtained some new understandings. |
| keywords:North China Ctaton potash Ordovician Gondwana lithofacies paleogeography |
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