Abstract Along tectonically active margins, the difference in elevations between global sea levels during highstands and uplifted marine terraces is a function of both tectonics and glacial-isostatic adjustment (GIA). However, disentangling the relative influence of these two processes remains a challenge for those trying to gain insights into either process. In this study, we outline a strategy for isolating the tectonic contribution to marine isotope stage (MIS) 5e and 5a marine terrace elevations for the southern California coast by determining the cosmogenic radionuclide burial age and elevation of the early Pleistocene (1.48 ± 0.17 Ma) Clairemont Terrace in San Diego. Using this older terrace as a datum for calculating tectonic uplift rate provides a much longer time period to average out uncertainties in past local or relative sea levels (RSL) that arise from ambiguities in GIA parameters and global meltwater volumes. The assumption of constant uplift rates is warranted for this portion of the California coast given its relatively simple tectonic setting on the rift flank of the Salton Trough. From this approach, we determine an average uplift rate of 0.066 ± 0.020 mm/yr or 0.055 ± 0.013 mm/yr, depending on the RSL model used for the time of the Clairemont Terrace formation, for much of the San Diego coastline. Correcting for this tectonic uplift rate leaves an estimate of 15.1 + 2.6/-3.1 m (16.4 + 1.9/-2.6 m) and 4.8 ± 1.9 m (5.6 ± 1.5 m) for RSL during MIS5e and MIS5a, respectively. These new estimates of MIS5e and MIS5a sea levels along the southern California coast provide important constraints on GIA parameters and former ocean and ice volumes.

中文翻译：

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修正构造隆升的 MIS5e 和 5a 海平面估计值，以南加州为例

摘要 沿着构造活动边缘，高位和抬升的海洋阶地期间全球海平面之间的海拔差异是构造和冰川均衡调整 (GIA) 的函数。然而，对于那些试图深入了解这两个过程的人来说，解开这两个过程的相对影响仍然是一个挑战。在这项研究中，我们概述了通过确定宇宙成因放射性核素埋藏年龄和早更新世 (1.48 ± 0.17 Ma) 的海拔来隔离对南加州海岸海洋同位素阶段 (MIS) 5e 和 5a 海洋阶地海拔的构造贡献的策略圣地亚哥的克莱尔蒙特露台。使用这个较旧的阶地作为计算构造抬升速率的基准提供了更长的时间来平均化过去局部或相对海平面 (RSL) 的不确定性，这些不确定性是由 GIA 参数和全球融水量的模糊性引起的。鉴于其位于索尔顿海槽裂谷侧翼的相对简单的构造环境，加利福尼亚海岸的这一部分有必要假设抬升率恒定。根据这种方法，我们确定了 0.066 ± 0.020 毫米/年或 0.055 ± 0.013 毫米/年的平均抬升率，这取决于圣地亚哥大部分海岸线在克莱尔蒙特台地形成时使用的 RSL 模型。对这种构造抬升率进行修正后，MIS5e 和 MIS5a 期间的 RSL 估计值分别为 15.1 + 2.6/-3.1 m (16.4 + 1.9/-2.6 m) 和 4.8 ± 1.9 m (5.6 ± 1.5 m)。