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Fractured, altered, and faulted basement in northeastern Oklahoma: Implications for induced seismicity
Journal of Structural Geology ( IF 2.6 ) Pub Date : 2021-04-02 , DOI: 10.1016/j.jsg.2021.104330
M. Hamilton , B. Carpenter , C. Johnston , F. Kolawole , S. Evans , R.D. Elmore

Due to a decade of wastewater injection-triggered seismicity, the crystalline basement of northern Oklahoma has become the subject of intensive research, almost all of which has relied upon remote sensing or analog models and materials due to a near total absence of outcrops. This study reports relevant characteristics of material in drill cores from the area, the best available analog for seismogenic northern Oklahoma basement. Fractures are present in all cores, remain abundant over 100 m below the top of basement, commonly have steep inclinations (≥70°) and are nearly universally mineralized. Many fractures show evidence of slip such as slickenlines, vein offset, brecciation, and in one core injectite formation. Fractures are mineralized by carbonates and/or phyllosilicates along with various other minerals, some contain vugs, and many contain multiple generations of minerals. Color changes suggestive of redox processes, including possible paleoweathering, are associated with fractures and proximity to the basement unconformity. Paragenesis of fracture minerals and variations in geochemical analyses of altered rocks indicate complex histories of deformation and fluid activity. The abundance of fractures in cores indicates that the upper basement of northeastern Oklahoma is much less “intact” than commonly assumed; it instead shows similarities to fractured basement plays, which may provide a more reasonable comparison for future work.



中文翻译:

俄克拉何马州东北部地下室的破裂,蚀变和断层:诱发地震活动的意义

由于废水注入触发了十多年的地震活动,俄克拉荷马州北部的晶体地下室已成为深入研究的主题,由于几乎完全没有露头,几乎所有这些都依赖于遥感或模拟模型和材料。这项研究报告了该地区钻芯中材料的相关特征,这是俄克拉荷马州北部地震发生地下室的最佳可用类似物。裂缝存在于所有岩心中,在地下室顶部以下100 m处仍很丰富,通常具有陡峭的倾斜度(≥70°)并且几乎普遍被矿化。许多骨折均显示出滑动迹象,例如,光滑线,静脉偏移,胸裂和在一个核心注入岩层中形成。碳酸盐和/或页硅酸盐与各种其他矿物质一起使骨折矿化,其中一些含有孔洞,许多都含有多代矿物质。暗示氧化还原过程的颜色变化,包括可能的古风化,与裂缝和接近基底不整合面有关。裂隙矿物的共生性和蚀变岩石的地球化学分析中的变化表明了变形和流体活动的复杂历史。岩心中的大量裂缝表明,俄克拉荷马州东北部的上层基底比通常认为的“完整”程度要小得多。相反,它显示了与地下室裂缝的相似之处,可以为以后的工作提供更合理的比较。裂隙矿物的共生性和蚀变岩石的地球化学分析中的变化表明了变形和流体活动的复杂历史。岩心中的大量裂缝表明,俄克拉荷马州东北部的上层基底比通常认为的“完整”程度要小得多。相反,它显示了与地下室裂缝的相似之处,可以为以后的工作提供更合理的比较。裂隙矿物的共生性和蚀变岩石的地球化学分析中的变化表明了变形和流体活动的复杂历史。岩心中的大量裂缝表明,俄克拉荷马州东北部的上层基底比通常认为的“完整”程度要小得多。相反,它显示了与地下室裂缝的相似之处,可以为以后的工作提供更合理的比较。

更新日期:2021-04-21
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