Comparison of clast frequency and size in the resurge deposits at the Chesapeake Bay impact structure (Eyreville A and Langley cores): Clues to the resurge process
Comparison of clast frequency and size in the resurge deposits at the Chesapeake Bay impact structure (Eyreville A and Langley cores): Clues to the resurge process
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切萨皮克湾撞击构造（艾尔维尔 A 和兰利岩心）再生沉积物中碎屑频率和大小的比较：再生过程的线索
DOI：
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发表时间：
2009
期刊：
影响因子：
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通讯作者：
L. Edwards
中科院分区：
文献类型：
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作者：
J. Ormö;E. Sturkell;J. Horton;D. Powars;L. Edwards
松散沉积层的坍塌和向内塌陷使切萨皮克湾的撞击结构远远超出了中央基底火山口。在火山口塌陷期间，沉积物携带的水涌回火山口。在这里，我们分析了这些再喷发沉积物的碎屑频率和粒度，这些再喷发沉积物位于塌陷区最外面的一个岩心孔中（即，兰利）以及来自地下室陨石坑护城河的核心孔（即，Eyreville A）.碎屑物源和流动动力学的比较表明，在这两个位置，碎屑频率和大小在下部单元（我们认为其主要由滑塌物质组成）和上部水输送单元（即，重新存入存款。物质对再生存款的贡献主要受剥离和侵蚀的控制。这包括夹带回落喷出物和沉积物从周围的海底侵蚀，被发现是占主导地位的兰利，和滑塌的材料，覆盖环形槽和基底陨石坑，被发现是占主导地位的Eyreville。Eyreville的结晶碎屑含量高于兰利。有模棱两可的证据表明，从一个崩溃的中央水羽反复活，或者，第二次复活脉冲，以及过渡到振荡复活。与沉积物与水的比例相对较低的其他一些海洋目标陨石坑的再喷发沉积物相比，再喷发物质显示出更多的类似碎屑流的迁移。这一结果很可能是容易分解的宿主沉积物和相对较浅的目标水深相结合的结果。
Collapse and inward slumping of unconsolidated sedimentary strata expanded the Chesapeake Bay impact structure far beyond its central basement crater. During crater collapse, sediment-loaded water surged back to fill the crater. Here, we analyze clast frequency and granulometry of these resurge deposits in one core hole from the outermost part of the collapsed zone (i.e., Langley) as well as a core hole from the moat of the basement crater (i.e., Eyreville A). Comparisons of clast provenance and flow dynamics show that at both locations, there is a clear change in clast frequency and size between a lower unit, which we interpret to be dominated by slumped material, and an upper, water-transported unit, i.e., resurge deposit. The contribution of material to the resurge deposit was primarily controlled by stripping and erosion. This includes entrainment of fallback ejecta and sediments eroded from the surrounding seafloor, found to be dominant at Langley, and slumped material that covered the annular trough and basement crater, found to be dominant at Eyreville. Eyreville shows a higher content of crystalline clasts than Langley. There is equivocal evidence for an anti-resurge from a collapsing central water plume or, alternatively, a second resurge pulse, as well as a transition into oscillating resurge. The resurge material shows more of a debris-flow–like transport compared to resurge deposits at some other marine target craters, where the ratio of sediment to water has been relatively low. This result is likely a consequence of the combination of easily disaggregated host sediments and a relatively shallow target water depth.