Usman Ayatu Ojonugwa, Abraham Ema Michael, Oknonkwo Churchill Chukwunonso, Chinwuko Augustine Ifeanyi, Azuoko George-Best
Applied Geophysics Program, Alex Ekwueme Federal University, Ikwo, Ebonyi, Nigeria.
Department of Physics, Federal College of Technology, Umunze, Nigeria.
Sci Rep. 2024 Jul 29;14(1):17368. doi: 10.1038/s41598-024-66927-9.
This research work aims at evaluating the geothermal energy potentials of the Rafin Rewa warm spring (RRWS) of the Precambrian Basement Complex in Nigeria as an alternative energy source using integrated aeromagnetic geophysical techniques. Four aeromagnetic dataset were acquired, assemblage, analyzed, and interpreted using integrated geophysical processing techniques of spectral analysis and Euler deconvolution. Qualitative interpretation of the residual anomalous map reveals a distribution of positive anomalies (> 53 nT) majorly in the central and southeastern regions, which are traced to the granitic rocks, while the low anomalies (< - 1.5 nT) have been traced to the RRWS location emanating from the coastal plain sands of the Pliocene, Pleistocene, Oligocene, and Miocene ages. Quantitatively, the depth to the top (DTT) of the anomalous bodies reveals a depression that is almost intersecting with the Curie point depth (CPD) plot at the RRWS location, which indicates high heat flow in the RRWS region. The Spectral Analysis results reveal that the DTT and the CPD in this area ranges from 0.512 to 0.761 km and 6.504 to 10.582 km, respectively while the average CPD is 8.543 ± 0.325 km. It is observed that the DTT and CPD decrease as one move away from the RRWS region. The computed heat flow average was 160.76 ± 19.09 mW/m within the RRWS region. The Euler deconvolution result reveals the presence of geological structures, which were interpreted as faults and fractures. The major fractures trend in the east-west (E-W) directions, while the minor fractures trend northeast-southwest (NE-SW) directions. The geochemical result presented shows that iconic compositions impact the convective heat transfer processes associated with geothermal systems. It was conclusively believed that regions with comparable shallow CPDs could be viable for further geothermal energy investigations.
本研究工作旨在利用综合航磁地球物理技术，评估尼日利亚前寒武纪基底杂岩中拉芬雷瓦温泉（RRWS）作为替代能源的地热能潜力。采集了四个航磁数据集，并使用频谱分析和欧拉反褶积等综合地球物理处理技术进行了组合、分析和解释。剩余异常图的定性解释表明，正异常（>53 nT）主要分布在中部和东南部地区，这些异常与花岗岩有关，而低异常（<-1.5 nT）则与上新世、更新世、渐新世和中新世海岸平原砂层形成的RRWS位置有关。从定量上看，异常体顶部深度（DTT）显示出一个凹陷，该凹陷在RRWS位置几乎与居里点深度（CPD）曲线相交，这表明RRWS地区热流较高。频谱分析结果表明，该区域的DTT和CPD分别在0.512至0.761千米和6.504至10.582千米之间，平均CPD为8.543±0.325千米。可以观察到，随着远离RRWS地区，DTT和CPD会降低。RRWS区域内计算出的平均热流为160.76±19.09毫瓦/平方米。欧拉反褶积结果揭示了地质构造的存在，这些构造被解释为断层和裂缝。主要裂缝走向为东西向（E-W），而次要裂缝走向为东北-西南向（NE-SW）。给出的地球化学结果表明，标志性成分影响与地热系统相关的对流热传递过程。最终得出结论，具有可比浅部CPD的区域可能适合进一步开展地热能调查。
