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Contrasting thermal evolution of the West African Equatorial and Central Atlantic continental margins
Gondwana Research ( IF 6.1 ) Pub Date : 2022-08-23 , DOI: 10.1016/j.gr.2022.08.010
M. Wildman , R. Brown , J. Ye , D. Chardon , D. Rouby , A.N. Kouamelan , M. Dall'Asta

The landscape of the West African continental margins is the product of tectonic, thermal and surface processes acting in concert during and following the breakup of Gondwana. Central Atlantic opening was marked by the emplacement of the Central Atlantic Magmatic Province (CAMP) and continental breakup proceeded through Late Jurassic and Early Cretaceous divergent tectonics while opening of the Equatorial Atlantic was dominated by early and mid-Cretaceous transform movement. The onshore erosional response to these events is poorly constrained yet is a crucial component of our understanding of topographic evolution and sediment transfer across continental margins. We present new apatite fission-track (AFT) data for 24 samples from Guinea and 11 samples from Ivory Coast, and thermal histories from inverse modelling. Our data and thermal histories show the following: the thermal effect of the CAMP across Guinea and Ivory Coast; rapid cooling along the coast during the early to mid-Cretaceous related to erosion of short-wavelength rift-shoulders; moderate cooling across longer wavelengths reflecting a pattern of erosion across flexural margin upwarps; and low cooling rates from the start of the Cenozoic to present day, consistent with low magnitudes of erosion inferred by onshore geomorphological data. We present our results alongside the published regional AFT dataset and draw inferences on the thermal and tectonic evolution of the onshore margin.



中文翻译:

对比西非赤道和中大西洋大陆边缘的热演化

西非大陆边缘的景观是冈瓦纳分裂期间和之后共同作用的构造、热力和地表过程的产物。中大西洋开放的标志是中大西洋岩浆省(CAMP)的就位,大陆分裂通过晚侏罗世和早白垩世的分歧构造进行,而赤道大西洋的开放则以早白垩世和中白垩世转换运动为主。对这些事件的陆上侵蚀反应很少受到限制,但它是我们理解地形演变和大陆边缘沉积物转移的关键组成部分。我们提供了来自几内亚的 24 个样品和来自科特迪瓦的 11 个样品的新磷灰石裂变轨迹 (AFT) 数据,以及来自逆建模的热历史。我们的数据和热历史显示如下: CAMP 对几内亚和科特迪瓦的热效应;白垩纪早期至中期沿海岸快速冷却,与短波裂肩的侵蚀有关;较长波长的适度冷却反映了弯曲边缘向上弯曲的侵蚀模式;从新生代开始到现在的低冷却速率,与陆上地貌数据推断的低程度侵蚀一致。我们将我们的结果与已发布的区域 AFT 数据集一起展示,并推断陆上边缘的热力和构造演化。较长波长的适度冷却反映了弯曲边缘向上弯曲的侵蚀模式;从新生代开始到现在的低冷却速率,与陆上地貌数据推断的低程度侵蚀一致。我们将我们的结果与已发布的区域 AFT 数据集一起展示,并推断陆上边缘的热力和构造演化。较长波长的适度冷却反映了弯曲边缘向上弯曲的侵蚀模式;从新生代开始到现在的低冷却速率,与陆上地貌数据推断的低程度侵蚀一致。我们将我们的结果与已发布的区域 AFT 数据集一起展示,并推断陆上边缘的热力和构造演化。

更新日期:2022-08-23
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