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A comparative study of contrasting structural styles in the range-front region of the northeastern Arctic National Wildlife Refuge, northeastern Brooks Range, Alaska.

机译：在阿拉斯加的布鲁克斯山脉东北部的北极北极国家野生动物保护区的山脉前部地区，对比构造样式的对比研究。

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摘要

The range front of the northeastern Brooks Range in the Arctic National Wildlife Refuge (ANWR) is defined by anticlinoria cored by a 'basement' complex of weakly metamorphosed sedimentary, volcanic and intrusive rocks. These anticlinoria are interpreted to reflect horses in a northward-propagating regional duplex between a floor thrust at depth in the 'basement' complex and a roof thrust near the base of the cover sequence. Lateral variations in the geometry of these range-front anticlinoria reflect changes in lithology and deformational style of both the 'basement' and its cover.;In contrast, to the west the pre-Mississippian rocks consist primarily of the mechanically homogeneous Devonian Okpilak batholith. The batholith was transported northward during Cenozoic thrusting and now forms a major topographic and structural high near the range front. The batholith probably shortened during thrusting as a homogeneous mass via penetrative strain. Because the Kayak Shale is thin to absent in the vicinity of the batholith, Mississippian and younger rocks remained attached to the batholith and shortened via penetrative strain and minor imbrication.;These two range-front areas form the central portion of two regional transects through northeastern ANWR. General area-balanced models for both transects suggest that the amount of total shortening is governed by the structural topography and the geometry of the basal detachment surface. While the structural topography of northeastern ANWR is reasonably well-constrained, the geometry of the basal detachment is not. Given a range in reasonable basal detachment geometries, shortening in both transects ranges from 16% to 61%. Detailed balanced cross sections based on subsurface and surface geologic data yield 46-48% shortening for both transects.;Two distinct structural geometries are displayed along the range front of northeastern ANWR. To the east, the large range-front anticlinorium is interpreted to reflect multiple horses of Cenozoic age within the stratified, slightly metamorphosed sedimentary and volcanic rocks of the pre-Mississippian 'basement'. During Cenozoic thrusting, these mechanically heterogeneous rocks deformed primarily via thrusting and related folding with minor penetrative strain. The Mississippian and younger cover sequence shortened via both thrust duplication and detachment folding above a detachment in the Mississippian Kayak Shale.
机译：北极国家野生动物保护区（ANWR）东北布鲁克斯山脉的山脉前缘是由软变沉积岩，火山岩和侵入岩的“基底”复合体为核心的反斜斜岩定义的。这些倒斜角被解释为在“地下室”深处的底板推力和掩盖序列底部附近的屋顶推力之间向北传播的区域双工中反映马匹。这些山峰前斜背岩的几何形状的横向变化反映了“基底”及其覆盖层的岩性和变形样式的变化。相反，在西侧，密西西比前岩主要由机械均质的泥盆纪奥克拉皮拉克岩基组成。在新生代逆冲作用中，该岩基被运往北部，现在在山脉前缘附近形成了主要的地形和构造高点。岩心可能在穿透过程中通过渗透应变缩短为均质块。由于皮划艇页岩在基岩层附近很薄至不存在，密西西比和较年轻的岩石仍然附着在基岩层上，并且由于渗透应变和较小的胶结作用而缩短了；这两个范围前缘区域形成了穿过东北方向的两个区域样带的中心部分ANWR。这两个样条的通用面积平衡模型表明，总缩短量由结构形貌和基底脱离表面的几何形状控制。尽管东北ANWR的结构地形受到了很好的约束，但基底脱离的几何形状却没有。给定合理的基础脱离几何范围，两个样条的缩短范围从16％到61％。根据地下和地表地质数据得出的详细平衡截面图，两个断面均缩短了46％至48％。在东部，大范围的前部反气候层被解释为反映了密西西比河前“基底”的层状，略微变质的沉积和火山岩中的新生代马。在新生代逆冲作用中，这些机械非均质岩石主要通过逆冲作用和相关的折叠以及较小的渗透应变而变形。密西西比河和年轻的盖层序列通过逆冲推覆和分离折叠在密西西比州皮划艇页岩上方的一个分支之上而缩短了。

著录项

  • 作者

    Hanks, Catherine Leigh.;

  • 作者单位

    University of Alaska Fairbanks.;

  • 授予单位 University of Alaska Fairbanks.;
  • 学科 Geology.
  • 学位 Ph.D.
  • 年度 1991
  • 页码 308 p.
  • 总页数 308
  • 原文格式 PDF
  • 正文语种 eng
  • 中图分类
  • 关键词

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