| 鄂尔多斯盆地东缘奥陶纪马家沟期边界断层的新认识及其对成钾凹陷的控制 |
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| 引用本文：桂宝玲,张永生,邢恩袁,彭渊,陈天宇,毛亚辉,张文君,赵海彤,蒋苏扬.2024.鄂尔多斯盆地东缘奥陶纪马家沟期边界断层的新认识及其对成钾凹陷的控制[J].地球学报,45(5):678-690. |
| DOI：10.3975/cagsb.2024.080801 |
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| 基金项目:国家重点研发计划课题“重点含钾盆地富钾规律、战略选区与深部探测技术示范”(编号: 2017YFC0602806);国家自然科学基金“鄂尔多斯盆地东缘奥陶纪构造特征及其对成钾凹陷的控制”(编号: 41702214);中国地质调查局地质调查二级项目“陕东-晋西地区气钾兼探战略调查”(编号: DD20179624);“西部地区钾盐矿产远景调查评价”(编号: DD20160054) |
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| 中文摘要:鄂尔多斯盆地陕北盐盆奥陶系马家沟组具备良好的成钾潜力, 然而, 当前仅勘探到薄钾石盐矿层和厚层钾石盐矿化段, 大规模钾盐矿尚未发现。通过分析鄂尔多斯盆地东缘地震剖面的构造特征, 认为盆地东缘晋西挠褶带西部马五6亚段沉积期存在活动边界正断层。在该断层作用下, 形成东断西超的活动同沉积凹陷, 富钾卤水大量汇聚于此。在持续干旱的强蒸发环境下, 卤水持续浓缩, 成钾窗口出现, 钾石盐大规模析出, 进而形成整装海相优质固体钾石盐矿床。侏罗纪末期, 挤压应力导致成钾凹陷抬升, 形成古凹今隆的格局, 钾盐层抬升至较浅部位, 有利于水溶法经济开采。 |
| 中文关键词:鄂尔多斯盆地东缘 晋西挠褶带 奥陶系马家沟组 海相钾盐 构造成钾 古凹今隆 |
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| New Understanding of Boundary Fault Control of Potassium Sag Formation in the Majiagou Period of the Ordovician in the Eastern Margin of the Ordos Basin |
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| Abstract:The Ordovician Majiagou Formation in the northern Shaanxi salt basin has good potential for potassium mineral formation, but only thin potassium beds and thick beds of potassium mineralization, rather than large-scale potash, have been found. As a result of performing a structure analysis of seismic profiles in the eastern margin of the Ordos Basin, we believe that there was a boudary normal fault in the period of deposition of the sixth submember of the Majiagou Formation in the Jinxi flexure fold belt. The boudary normal fault formed a syndepositional depression, and a large amount of brine rich in potassium accumulated within the sag. With continuing drought, strong evaporation, and continuous enrichment, a brine potassium window appeared, and large-scale sylvine separated out, forming a monoblock of high-quality, marine, solid potassium salt deposits. During the Mesozoic Era, compressional stress caused the potassium sag to rise, forming a pattern of ancient depression and subsequent uplift. The potassium salt beds were uplifted to the shallow part of the basin, which is convenient for economic exploitation by the water solution method. |
| keywords:eastern margin of Ordos Basin Jinxi flexure fold belt Ordovician Majiagou Formation marine potash structural forming of potassium depression in ancient and upheaval in present |
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