The Arctic Eurekan orogen: A most unusual fold-and-thrust belt
The Arctic Eurekan orogen: A most unusual fold-and-thrust belt
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北极尤里卡造山带：最不寻常的褶皱逆冲带
DOI：
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发表时间：
1989
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影响因子：
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通讯作者：
S. M. Phillips
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文献类型：
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作者：
D. D. De Paor;DWIGHT C. Bradley;G. Eisenstadt;S. M. Phillips
北美洲最北端的第三纪尤里坎造山带与标准的褶皱冲断带在几个方面不同。它缺乏变质-深成腹地和楔形剖面；相反，埃尔斯米尔岛东南部2公里高的山脉面临正面推力，而晕轮构造多边形、温和翘曲和低沉的地形从系统中心的阿克塞尔海贝格岛延伸到其后方的斯维尔德鲁普边缘。碎屑岩不是位于单一的弯曲前部，而是分布在多个逆冲断块之间的低地形上。地层年龄、位移量和应变强度均向克拉通方向增大，体系的宽长比异常高。造山带是由于格陵兰9号相对于北美的枢轴运动，在埃尔斯米尔群岛和阿克塞尔海贝格群岛形成了一条辫状新生代板块边界，而不是以前提出的在纳尔斯海峡的一次转换。这个编织系统的三个主要部分是帕里什冰川、维斯尔湾和斯托尔兹逆冲。它们在南部向旋转的构造极消亡，而在北部，运动被从哈森湖延伸到格陵兰岛北部的右旋挤压带所容纳。埃尔斯米尔岛的实地研究结合以前工作的区域综合表明，尤里坎变形样式表明了关键的构造作用，容纳格陵兰9号位移所需的收缩在幅度上与尤里坎构造记录的相似，大陆构造的年龄与拉布拉多海和巴芬湾海底扩张的古地磁记录相一致。以前提出的左旋走滑位移没有得到证实；相反，该系统典型的是东向逆冲和右旋扭动断层。我们认为，随着北大西洋裂谷系统贯穿整个劳亚大陆，尤里坎造山活动标志着从尖端传播到枢轴构造作用的转变。
The Tertiary Eurekan orogen of northernmost North America differs from a standard fold-and-thrust belt in several respects. It lacks a metamorphic-plutonic hinterland and wedge-shaped profile; instead, 2-km-high mountains of southeast Ellesmere Island face the frontal thrust, whereas halotectonic polygons, gentle warps, and subdued topography extend from Axel Heiberg Island in the center of the system back to the Sverdrup Rim at its rear. Clastic deposits are not located in a single flexural foredeep but are distributed in topographic lows amid several thrust sheets. The age of the stratigraphy, amount of displacement, and intensity of strain all increase cratonward, and the system9s width-to-length ratio is anomalously high. The orogen is attributed to Greenland9s pivotal movement relative to North America, which formed a braided Cenozoic plate boundary in Ellesmere and Axel Heiberg Islands, not a single transform in Nares Strait as previously proposed. The three major strands of this braided system are the Parrish Glacier, Vesle Fiord, and Stolz thrusts. They die out toward a structural pole of rotation in the south, whereas to the north, movement is accommodated by a dextral transpression zone extending from Lake Hazen to northern Greenland. Field studies on Ellesmere Island combined with a regional synthesis of previous work show that Eurekan deformation style is indicative of pivotal tectonism, that the contraction necessary to accommodate Greenland9s displacement is similar in magnitude to that documented by Eurekan structures, and that the ages of continental structures are compatible with the paleomagnetic record of seafloor spreading in Labrador Sea and Baffin Bay. Previously proposed sinistral strike-slip displacement is not confirmed; rather, eastvergent thrusts and dextral wrench faults typify the system. We propose that the Eurekan orogeny marked a change from tip propagation to pivotal tectonism as the North Atlantic rift system penetrated the entire width of the Laurasian continent.