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首页> 外文学位 >Structure and crustal balance of the Herald Arch and Hope Basin in the Chukchi Sea, Alaska.
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Structure and crustal balance of the Herald Arch and Hope Basin in the Chukchi Sea, Alaska.

机译：阿拉斯加楚科奇海先驱拱与希望盆地的结构和地壳平衡。

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摘要

The Herald Arch is a structural high bounded by the Herald Thrust fault to the northeast and by a normal, or possibly strike-slip, fault to the southwest in the Chukchi Sea, off the northwest coast of Alaska. The thrust continues for approximately 60 kilometers from the northwest tip of the Lisburne Peninsula into the Chukchi Sea. Its dip varies from nearly 60 degrees in the east, to 20 degrees in the west before terminating on the available seismic data. Closer to the shore, the detachment of the Herald Thrust occurs at the edge of a Devonian rift basin containing the Franklinian Sequence. Moving towards the northwest, the rift diminishes along with the detachment of the Herald Thrust. Northeast of the Herald Thrust in the Colville Basin, the anticlines and thrust faults of the Brookian layers diminish in magnitude and displacement from the Lisburne Peninsula to the northwest. The depth to the reflection Moho decreases from approximately 37 km beneath the Colville Basin to 28 km under the Hope Basin to the south. Estimates for the amount of extension required to produce the present day crustal thickness are at least 20% less than the amount of Tertiary stretching that has been documented by restoration of supracrustal normal faults. The thinning of the crust could be attributed to differential spreading where the upper crust was stretched less then the lower crust and mantle, or due to and older, mid Cretaceous, extensional event that has gone unrecognized on the seismic data. A magnetic high that corresponds closely to the Herald Arch could be evidence of magmatic material brought up during the mid-Cretaceous spreading event.
机译：先驱拱是由东北的先驱冲断层和位于阿拉斯加西北海岸楚科奇海西南部的正常或可能是走滑断层所界定的结构性高地。从利斯本半岛的西北端到楚科奇海，推力持续了大约60公里。它的倾角从东部的近60度变化到西部的20度，然后终止可用的地震数据。离海岸较近，先驱冲刺的脱离发生在包含富兰克林阶列的泥盆纪裂谷盆地的边缘。向西北移动时，裂隙随着先驱冲刺的脱离而减小。在科尔维尔盆地的先驱冲刺的东北部，布鲁克斯层的背斜和逆冲断层从里斯本半岛向西北移动的幅度和位移减小。反射莫霍面的深度从科尔维尔盆地下方约37 km减小到南部希望盆地下方28 km。估计今天产生的地壳厚度所需的延伸量至少比恢复上壳正断层所记录的第三级伸展量小至少20％。地壳变薄的原因可能是差异扩散，即上地壳的伸展程度小于下地壳和地幔的伸展程度，或者归因于白垩纪中期的伸展事件，而该事件在地震数据中未能得到认识。高度接近先驱拱的磁高可能是在白垩纪中期扩散事件中产生的岩浆物质的证据。

著录项

  • 作者

    Patthoff, D. Alex.;

  • 作者单位

    West Virginia University.;

  • 授予单位 West Virginia University.;
  • 学科 Geology.
  • 学位 M.S.
  • 年度 2008
  • 页码 113 p.
  • 总页数 113
  • 原文格式 PDF
  • 正文语种 eng
  • 中图分类 地质学;
  • 关键词

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