Structural controls on the localization of the mineralized Copper Cliff embayment and the Copper Cliff Offset dyke, Sudbury Igneous Complex, Canada
Structural controls on the localization of the mineralized Copper Cliff embayment and the Copper Cliff Offset dyke, Sudbury Igneous Complex, Canada
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对加拿大萨德伯里火成岩矿化铜崖海湾和铜崖偏移堤坝本地化的结构控制
DOI：
10.1016/j.oregeorev.2021.104071
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发表时间：
2021
影响因子：
3.3
通讯作者：
Lightfoot
中科院分区：
文献类型：
--
作者：
Mathieu;Riller;Gibson;Lightfoot
萨德伯里火成杂岩（SIC）的主体是一个1.5-5公里厚的撞击熔融岩层状岩片，由于与主体基底和连接的岩墙（分别称为次层和偏置岩墙）相关的岩浆Ni-Cu-PGE硫化物矿床，因此对其进行了深入研究。矿化偏置岩脉的侵位模式，通过形态火山口底部的不规则性（海湾）和风格的后陨石坑变形，影响偏置岩脉连接到主质量还没有完全理解。铜悬崖湾（CCE）和偏移（CCO）堤的实地研究有助于解开熔融侵位的模式和影响前断层在南部SIC变形中的作用。现场关系表明，CCO岩墙形成之前，CCE和子层的化学充分演变。相应的熔体注入下盘岩石削弱预冲击变形和陨石坑作为一个长期的事件，与贫瘠的石英diaphragm（QD）侵位之前矿化，包含石英diaphragm（IQD）。块状硫化物矿体似乎是在岩脉演化的后期形成的，需要硅酸盐岩浆和硫化物熔体的物理分离（分离）。NW-SE缩短褶皱和断层的地层托管的CCO堤坝和变形促进了通过重新激活的E-W走向，冲击前的断层。使用3D建模和现场约束恢复堤坝和海湾的初始几何形状，有助于完善沿着主要断层的总滑动估计，并证实熔体在重力作用下向下迁移到CCO堤坝中。
The Main Mass of the Sudbury Igneous Complex (SIC) is a 1.5–5 km thick, layered sheet of impact melt rocks, intensely studied because of the magmatic Ni-Cu-PGE sulfide deposits associated with the base of the Main Mass and connected dykes, known as the Sublayer and Offset dykes, respectively. The mode of emplacement of the mineralized Offset dykes that connect to the Main Mass through morphologic crater-floor irregularities (embayments) and the style of post-cratering deformation that affected the Offset dykes is not fully understood. This field-based study of the Copper Cliff Embayment (CCE) and Offset (CCO) dyke contributes to unraveling the mode of melt emplacement and the role of pre-impact faults in the deformation of the southern SIC. Field relationships indicate that the CCO dyke formed before the CCE and Sublayer were chemically fully evolved. Respective melts were injected into footwall rocks weakened by pre-impact deformation and cratering as a protracted event, with barren quartz diorite (QD) emplaced prior to mineralized, inclusion-bearing quartz diorite (IQD). Massive sulfide ore bodies appear to have formed late in the evolution of the dyke and physical separation (decoupling) of silicate magma and sulfide melt is required. NW-SE-shortening folded and faulted the strata hosting the CCO dyke and deformation was facilitated through re-activated E-W-striking, pre-impact faults. Restoring the initial geometry of the dyke and embayment, using 3D modelling and field constraints, helped to refine total slip estimates along major faults and confirmed that melts migrated gravitationally downward into the CCO dyke.
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