Characterizing strain between rigid crustal blocks in the southern Cascadia forearc: Quaternary faults and folds of the northern Sacramento Valley, California
Characterizing strain between rigid crustal blocks in the southern Cascadia forearc: Quaternary faults and folds of the northern Sacramento Valley, California
复制标题
卡斯卡迪亚前弧南部刚性地壳块之间的应变特征：加利福尼亚州萨克拉门托谷北部的第四纪断层和褶皱
作者：
Stephen Angster;S. Wesnousky;P. Figueiredo;L. Owen;T. L. Sawyer
美国加利福尼亚州萨克拉门托河谷北部晚第四纪地表的地形剖面显示，一系列活动的东向和北东向断层和褶皱发生错动和递进褶皱。晚更新世翘曲河流阶地上沉积物的光激发发光年龄沿萨克拉门托河产生不同的切割速率，表明Inks Creek褶皱系统背斜上方的构造抬升速度为0.2±0.1 mm/a，红崖断裂的构造抬升速度为0.6±0.2 mm/a。抬升速率相当于地壳北向缩短1.3±0.4 mm/年，占了萨克拉门托河谷北部大地测量到的所有收缩应变，但只是内华达山脉-大山谷和俄勒冈海岸地块之间远场收缩的一部分。这些构造定义了两个地块之间的挤压转换的南界。
Topographic profiles across late Quaternary surfaces in the northern Sacramento Valley (California, USA) show offset and progressive folding on series of active east- and northeast-trending faults and folds. Optically stimulated luminescence ages on deposits draping a warped late Pleistocene river terrace yielded differential incision rates along the Sacramento River and indicate tectonic uplift equal to 0.2 ± 0.1 and 0.6 ± 0.2 mm/yr above the anticline of the Inks Creek fold system and Red Bluff fault, respectively. Uplift rates correspond to a total of 1.3 ± 0.4 mm/yr of north-directed crustal shortening, accounting for all of the geodetically observed contractional strain in the northern Sacramento Valley, but only part of the far-field contraction between the Sierra Nevada–Great Valley and Oregon Coast blocks. These structures define the southern limit of the transpressional transition between the two blocks.