Products of onshore passive continental margin erosion are best preserved in offshore sedimentary basins. Therefore, these basins potentially hold a recoverable record of the onshore erosion history. Here, we present apatite fission track (AFT) data for 13 samples from a borehole in the southern Walvis basin, offshore Namibia. All samples show AFT central ages older or similar to their respective stratigraphic ages, while many single grain ages are older, implying none of the samples has been totally annealed post‐deposition. Furthermore, large dispersion in single grain ages in some samples suggests multiple age components related to separate source regions. Using Bayesian mixture modelling we classify single grain ages from a given sample to particular age components to create ‘subsamples’ and then jointly invert the entire dataset to obtain a thermal history. For each sample, the post‐depositional thermal history is required to be the same for all age components, but each component (‘subsample’) has an independent pre‐depositional thermal history. With this approach we can resolve pre‐ and post‐depositional thermal events and identify changes in sediment provenance in response to the syn‐ and post‐rift tectonic evolution of Namibia and southern Africa. Apatite U‐Pb and compositional data obtained during the acquisition of LA‐ICP‐MS FT data are also presented to help track changes in provenance with time. We constrain multiple thermal events linked to the exhumation and burial history of the continental and offshore sectors of the margin over a longer timescale than has been possible using only onshore AFT thermochronological data.

中文翻译：

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从水槽到水源：使用海上测温数据提取纳米比亚的陆上侵蚀信号

陆上被动大陆边缘侵蚀的产物最好保存在近海沉积盆地中。因此，这些盆地可能拥有陆上侵蚀历史的可恢复记录。在这里，我们提供了纳米比亚近海沃尔维斯盆地南部钻孔中的13个样品的磷灰石裂变径迹（AFT）数据。所有样品均显示出AFT中心年龄更早或与其各自的地层年龄相近，而许多单一颗粒年龄都较老，这意味着没有一个样品在沉积后已完全退火。此外，在一些样品中，单个谷物年龄的较大分散表明与单独的来源地区有关的多个年龄成分。使用贝叶斯混合模型，我们将给定样本中的单个晶粒年龄分类为特定的年龄成分，以创建“子样本”，然后联合反转整个数据集以获得热历史。对于每个样本，要求所有年龄成分的沉积后热历史都相同，但是每个成分（“子样本”）都具有独立的沉积前热历史。通过这种方法，我们可以解决沉积前和沉积后的热事件，并根据纳米比亚和南部非洲的裂谷后和裂谷后构造演化确定沉积物来源的变化。还介绍了在获取LA-ICP-MS FT数据期间获得的磷灰石U-Pb和成分数据，以帮助追踪物源随时间的变化。