Abstract In this study, we provide the first detrital apatite (U–Th-Sm)/He (AHe) and zircon U–Pb ages to establish a detailed short-term chronology of the burial and exhumation history, which occurred in the Coastal Cordillera along the forearc domain of Ecuador. First, our results allowed us to define a range of maximum deposition ages for the Angostura Formation from 9.6 ± 0.2 Ma to 11.5 ± 0.6 Ma, which records high enough temperatures to partially reset AHe ages. QTQt thermal inverse modeling of the AHe dataset reveals three main periods of exhumation along the Costal Cordillera at ∼2 Ma, ∼5–6 Ma and ∼8–10 Ma, independent of the sample geographic locations. We discuss the origin of these periods of exhumation in relation to the geodynamic frame. The oldest exhumation event, at ∼8–10 Ma, evidenced locally along fault systems, could be related to overriding plate kinematic changes or early arrival of Carnegie Ridge. The intermediate exhumation period, at ∼5–6 Ma, could be explained by a later arrival of the Carnegie Ridge or to the subduction of an along-strike positive relief of the ridge. Later, subduction of sea-floor asperities could be responsible for heterogeneous uplift of the Coastal Cordillera during the Pleistocene (∼2 Ma) that induced exhumation as supported by our models. These results are corroborated by previous studies and demonstrate that AHe data are sensitive enough to provide reliable constraints in sedimentary domains.

中文翻译：

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厄瓜多尔沿海科迪勒拉发掘的第一个时间限制：地球动力学影响

摘要 在这项研究中，我们提供了第一个碎屑磷灰石 (U-Th-Sm)/He (AHe) 和锆石 U-Pb 年龄，以建立发生在沿海山脉的埋藏和挖掘历史的详细短期年表。沿厄瓜多尔的前弧域。首先，我们的结果使我们能够定义 Angostura 组的最大沉积年龄范围，从 9.6 ± 0.2 Ma 到 11.5 ± 0.6 Ma，该范围记录了足够高的温度以部分重置 AHe 年龄。AHe 数据集的 QTQt 热逆模型揭示了沿海岸山脉在~2 Ma、~5-6 Ma 和~8-10 Ma 的三个主要剥露时期，与样本地理位置无关。我们讨论了与地球动力学框架相关的这些挖掘时期的起源。最古老的折返事件，大约 8-10 Ma，沿断层系统局部出现，可能与压倒性的板块运动学变化或卡内基海脊的提前到达有关。大约 5-6 Ma 的中间折返期可以用卡内基海脊的较晚到达或海脊沿走向的正浮雕的俯冲来解释。后来，海底凹凸不平的俯冲可能是更新世（~2 Ma）期间沿海山脉的异质隆起的原因，这引起了我们模型的支持。这些结果得到了先前研究的证实，并表明 AHe 数据足够敏感，可以在沉积域中提供可靠的约束。可以解释为卡内基海脊较晚到达或海脊沿走向的正浮雕的俯冲。后来，海底凹凸不平的俯冲可能是更新世（~2 Ma）期间沿海山脉的异质隆起的原因，这引起了我们模型的支持。这些结果得到了先前研究的证实，并表明 AHe 数据足够敏感，可以在沉积域中提供可靠的约束。可以解释为卡内基海脊的较晚到达或海脊沿走向的正浮雕的俯冲。后来，海底凹凸不平的俯冲可能是更新世（~2 Ma）期间沿海山脉的异质隆起的原因，这引起了我们模型的支持。这些结果得到了先前研究的证实，并表明 AHe 数据足够敏感，可以在沉积域中提供可靠的约束。