The evolution of the Onaping Formation at the Sudbury impact structure
The evolution of the Onaping Formation at the Sudbury impact structure
复制标题
萨德伯里冲击构造奥纳平组的演化
DOI：
10.1111/j.1945-5100.2010.01057.x
复制
发表时间：
2010
影响因子：
2.2
通讯作者：
N. Artemieva
中科院分区：
文献类型：
--
作者：
R. Grieve;D. Ames;J. Morgan;N. Artemieva
摘要/ Abstract摘要：在萨德伯里撞击构造的萨德伯里火成岩杂岩（SIC）之上，1.4 ~ 1.6 km厚的奥纳平组由一系列复杂的角砾岩和“熔融体”组成。基于冲击岩屑和各种“玻璃状”相的存在，奥纳平被描述为一种“闪质”角砾岩，其起源，至少部分是作为回退物质。最近的制图和重新定义的地层学强调了其各个玻璃相的异同，无论是碎屑类型还是离散侵入体。综述了奥纳平角砾岩和其他覆在冲击熔体上的“闪质”角砾岩的性质。相对厚度、内部地层岩性特征和沉积单元的相对年代学表明，奥坪的形成在一定时期内经历了多种作用。萨德伯里构造形成于前陆盆地，水在奥纳平的演化中起着重要作用，形成过程中形成了一个主要的热液系统。综上所述，对Onaping的观察和解释为Onaping的起源提出了一个可行的假设，该假设不仅包括撞击，还包括海水与撞击熔体的相互作用，导致涉及原始碳化硅材料的反复爆炸相互作用，并与预先存在的岩性混合。由于原始碳化硅材料侵入到不断演变和增厚的Onaping中，这使得额外的角化事件变得复杂。随着系统的进化，破碎机制发生了变化，并在奥纳平上部三分之二的形成过程中涉及到囊泡作用。
Abstract– The 1.4–1.6 km thick Onaping Formation consists of a complex series of breccias and “melt bodies” lying above the Sudbury Igneous Complex (SIC) at the Sudbury impact structure. Based on the presence of shocked lithic clasts and various “glassy” phases, the Onaping has been described as a “suevitic” breccia, with an origin, at least in part, as fallback material. Recent mapping and a redefined stratigraphy have emphasized similarities and differences in its various vitric phases, both as clast types and discrete intrusive bodies. The nature of the Onaping and that of other “suevitic” breccias overlying impact melt sheets is reviewed. The relative thickness, internal stratigraphic and lithological character, and the relative chronology of depositional units indicate multiple processes were involved over some time in the formation of the Onaping. The Sudbury structure formed in a foreland basin and water played an essential role in the evolution of the Onaping, as indicated by a major hydrothermal system generated during its formation. Taken together, observations and interpretations of the Onaping suggest a working hypothesis for the origin of the Onaping that includes not only impact but also the interaction of sea water with the impact melt, resulting in repeated explosive interactions involving proto‐SIC materials and mixing with pre‐existing lithologies. This is complicated by additional brecciation events due to the intrusion of proto‐SIC materials into the evolving and thickening Onaping. Fragmentation mechanisms changed as the system evolved and involved vesiculation in the formation of the upper two‐thirds of the Onaping.