Differential coastal uplift quantified by luminescence dating of marine terraces, central Cascadia forearc, Oregon
Differential coastal uplift quantified by luminescence dating of marine terraces, central Cascadia forearc, Oregon
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DOI：
10.1016/j.quascirev.2022.107853
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发表时间：
2022-12
影响因子：
4
通讯作者：
K. McKenzie;H. Kelsey;E. Kirby;T. Rittenour;K. Furlong
中科院分区：
文献类型：
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作者：
K. McKenzie;H. Kelsey;E. Kirby;T. Rittenour;K. Furlong
沿着卡斯卡迪亚会聚边缘海岸线的海洋阶地沿着的飞行记录了俯冲带上板块长期持续的地壳隆起。在亚基纳湾（俄勒冈州纽波特），先前推断的MIS 5（5a，5c和5e）海湾北部和南部海洋阶地的海拔差异意味着长期抬升速率的差异，这归因于沿着亚基纳湾断层的位移-推断位于海湾内的西向东走向断层。在这里，我们提出了第一个直接年龄的海洋阶地沉积在亚基纳湾使用发光测年的海洋阶地砂的阶地踏板，以量化长期和间隔隆起率。这些新的年龄结果结合高分辨率的地形数据，使我们能够完善以前的海洋阶地在亚基纳湾附近的映射，包括识别的MIS 5a阶地亚基纳湾南部。亚基纳湾北部和南部阶地的海拔差异证实了自晚更新世以来沿亚基纳湾断层沿着的相对位移。我们的研究结果意味着长期隆升率的差异，相对于海平面北部和南部的亚基纳湾自约。125ka;断层以南的抬升速率似乎相对稳定，为0.3-0.4 m/kyr，而断层以北的平均抬升速率更大，在过去约为0.7-0.9 m/kyr。12万5千。值得注意的是，断层以北的阶地高程需要随时间变化的抬升速率。MIS 5e和5c之间的尿潴留率似乎相对较低（≤0.1 m/kyr），但在MIS 5c和MIS 5a之间的20 kyr期间，尿潴留率增加至1.6 m/kyr。随后，在过去的180 kyr，隆起率似乎已经下降到0.7 m/kyr，但维持在约两倍的速度，该块南部的故障。这些结果需要时变滑动沿着Yaquina湾断层晚更新世以来。
Flights of marine terraces along the coastline of the Cascadia convergent margin record long-term, sustained crustal uplift of the subduction zone upper plate. At Yaquina Bay (Newport, Oregon) differences in the elevations of previously inferred MIS 5 (5a, 5c, and 5e) marine terraces north and south of the bay imply differences in the long-term uplift rate that are attributed to displacement along the Yaquina Bay fault – a west-to-east trending fault inferred to be located within the bay. Here we present the first direct ages for the marine terrace deposits at Yaquina Bay using luminescence dating of marine terrace sands on terrace treads to quantify long-term and interval uplift rates. These new age results in combination with high-resolution topographic data, allow us to refine previous mapping of marine terraces in the vicinity of Yaquina Bay, including the recognition of a MIS 5a terrace south of Yaquina Bay. Differences in the elevations of terraces north and south of Yaquina Bay confirm relative displacement along the Yaquina Bay fault since the late Pleistocene. Our results imply differences in the long-term uplift rate relative to sea level north and south of Yaquina Bay since ca. 125 ka; south of the fault, uplift rates appear to have been relatively constant at 0.3–0.4 m/kyr, whereas north of the fault, average uplift rates were greater, 0.7–0.9 m/kyr over the past ca. 125 kyrs. Notably, terrace elevations north of the fault require variations in uplift rate through time. Uplift rates appear to have been relatively low (≤0.1 m/kyr) between MIS 5e and 5c but increased to rates of ∼1.6 m/kyr in a ∼20 kyr period between MIS 5c and MIS 5a. Subsequently, uplift rates appear to have decreased to 0.7 m/kyr during the last ∼80 kyrs, but were sustained at rates approximately double that of the block south of the fault. These results require temporally variable slip along the Yaquina Bay fault since the late Pleistocene.