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The Olympic-Wallowa lineament: A new look at an old controversy
GSA Bulletin ( IF 4.9 ) Pub Date : 2021-01-01 , DOI: 10.1130/b35454.1
Stephen P. Reidel 1 , Karl R. Fecht 2 , Ingrid L. Hutter (Harrold) 3 , Terry L. Tolan 4 , Mickie A. Chamness 5
Affiliation  

The Olympic-Wallowa lineament (OWL) is an alignment of geologic structures extending nearly 650 km across the Pacific Northwest (PNW) and has been a controversial feature since it was first described nearly 80 years ago. It extends from the Olympic Peninsula–Puget Sound area of western Washington to the Wallowa Mountains of northeast Oregon, crossing through the Columbia Basin and forming the southern boundary of the Pasco and Walla Walla Basins. Within the Columbia Basin, the OWL is a wide zone that aligns with >250 km of folds and faults that are part of the Yakima fold and thrust belt. Although the OWL is recognized to be active with deformation continuing from the Miocene to Recent, there are two competing end-member interpretations on the style of deformation: that of a major through-going, dextral strike-slip or oblique-slip fault and that of a series of thrusted anticlines. We focus on that portion of the OWL in the central Columbia Basin that extends from the Walla Walla River in northeast Oregon to Rattlesnake Mountain in central Washington. East of Wallula Gap, the OWL is expressed as the Wallula fault zone along the north flank of the Horse Heaven Hills anticline and the south fork of the Walla Walla River, while west of Wallula Gap, there are three structural alignments: the Rattlesnake-Wallula structural alignment, the Horse Heaven Hills–Badlands structural alignment, and the Horn Rapids–Badger Coulee structural alignment. Except for the Horse Heaven Hills anticline, the structural trends west of Wallula Gap mainly consist of a series of doubly plunging, northeast-verging anticlines. We demonstrate that the OWL consists of north-verging, thrusted anticlines whose orientation and structure are controlled by a basement fault without any evidence of strike-slip or significant oblique-slip fault movement since at least the middle Miocene. The difference in structural deformation of the portion of the OWL to the east of Wallula Gap versus that to the west appears to be controlled by the thickness of pre-basalt sediment within the central Columbia Basin and structures therein.

中文翻译:

奥运-瓦洛娜(William-Wallowa)血统:旧争议的新视角

奥林匹克-瓦洛娜(Olympic-Wallowa)地貌(OWL)是沿西北太平洋(PNW)延伸近650公里的地质构造的排列,自从将近80年前首次描述以来,就一直是一个有争议的特征。它从华盛顿西部的奥林匹克半岛-普格特海湾地区一直延伸到俄勒冈州东北部的沃洛阿山脉,穿过哥伦比亚盆地,形成了帕斯科和瓦拉瓦拉盆地的南部边界。在哥伦比亚盆地内,OWL是一个宽阔的区域,与Yakima褶皱和逆冲带的一部分> 250 km的褶皱和断层对齐。尽管OWL被认为是活跃的,而且变形从中新世一直持续到最近,但对于变形样式,有两种相互竞争的最终成员解释:主要贯穿过程,右旋走滑或斜滑断裂以及一系列逆冲背斜。我们关注的是OWL在哥伦比亚中部的那部分,从俄勒冈州东北部的Walla Walla河一直延伸到华盛顿中部的响尾蛇山。瓦卢拉峡(Wallula Gap)以东,OWL表示为沿着马天堂山背斜线北侧和瓦拉瓦拉河(Walla Walla River)南叉的瓦卢拉断层带,而瓦卢拉峡(Wallula Gap)以西,则有三个结构性路线:响尾蛇-瓦卢拉结构路线,Horse Heaven Hills –Badlands结构路线和Horn Rapids–Badger Coulee结构路线。除了Horse Heaven Hills背斜以外,Wallula Gap以西的结构趋势主要由一系列向北倾斜的双倾角背斜组成。我们证明了OWL由北向,逆冲背斜组成,其方位和结构受基底断层控制,至少从中新世中期以来没有任何走滑或明显的斜滑断层运动的迹象。瓦卢拉峡以东与西部的OWL部分的结构变形差异似乎受哥伦比亚中部盆地内玄武岩前沉积物的厚度及其结构控制。
更新日期:2021-02-11
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