The Algoa Basin is a hydrocarbon potential basin which lies off the southern continental margin of South Africa, along the coastal region of Port Elizabeth area with both onshore and offshore components. Despite the continued consensus on the basin’s hydrocarbon potential, both its structural and stratigraphic geodynamics are still not well documented. In this study, gravity data constrained by borehole data was modelled to reveal onshore subsurface geology whereas the seismic sections were used for offshore. In addition, magnetic data was used to delineate magnetic zones and lineaments. The onshore magnetic results show the localised occurrence of large-scale geologic bodies, with high and positive anomalies forming bounding rims coincidental with the edges of the basin. The average depths to the top of the shallowest and deepest magnetic sources were estimated from the power spectrum to be approximately 0.4–0.6 km and 9.5 km, respectively. The onshore Bouguer gravity map is characterised by a gravity low zone over the basin’s sediment where it attains its lowest value over the depocentre. 2¾ D gravity modelling results along five profiles show that the basin comprises of two to three ‘“V” shaped’ sub-basins of shallow crustal depth with sediment thickness of up to 4.6 km. The models also revealed discontinuity in sediment units, confirming the diachronous nature of the Uitenhage Group. Analyses of offshore seven seismic sections show that the stratigraphic sequence consists of diachronous geological units, which are characterised by displacements, forming a series of minor and major faults. Complementary to onshore gravity models, seismic sections also shows relatively shallow vertical extension to the Paleozoic crustal basement between 1.3 and 5.3 km.

中文翻译：

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在评估南非东开普省 Algoa 盆地的地层和构造地球动力学时综合磁力、重力和地震数据

Algoa 盆地是一个潜在的油气盆地，位于南非南部大陆边缘，沿着伊丽莎白港地区的沿海地区，包括陆上和海上部分。尽管对该盆地的碳氢化合物潜力持续达成共识，但其构造和地层地球动力学仍未得到很好的记录。在这项研究中，受钻孔数据约束的重力数据被建模以揭示陆上地下地质，而地震剖面用于海上。此外，磁数据被用来描绘磁区和线条。陆上地磁结果显示，大尺度地质体局部发育，高正异常形成与盆地边缘重合的边界环。从功率谱估计到最浅和最深磁源顶部的平均深度分别约为 0.4-0.6 公里和 9.5 公里。陆上布格重力图的特点是在盆地沉积物上有一个重力低区，在那里它在沉积中心上达到最低值。沿五个剖面的 2¾ D 重力模拟结果表明，该盆地由两到三个地壳深度较浅的“V”形子盆地组成，沉积厚度达 4.6 公里。这些模型还揭示了沉积物单元的不连续性，证实了 Uitenhage 群的历时性质。近海7个地震剖面分析表明，地层层序由穿时地质单元组成，以位移为特征，形成一系列小断层和大断层。