Alejandra Carillo Ramirez

​Colombia has a number of geological contexts that could be favorable for the production of natural hydrogen. This is the case in the Cordillera Occidental, more specifically in the Cauca-Patía basin and in the southern part of the Sinu-San Jacinto basin, as well as in the southern part of the Lower Magdalena Valley basin. The Cauca-Patía basin shows an extension of the Cretaceous ophiolites, which lie beneath the folded sedimentary and volcanic-sedimentary sequence that extends into the eastern part of Cali. The basin is bounded on the east and west by ophiolites outcropping from the central and western cordilleras, in the northern and southern parts of these ranges. Northward, the lower Sinú-San Jacinto basin and the lower Magdalena valley feature Jurassic ophiolites, including two ultramafic bodies: Cerro Matoso and San José de Uré. Cerro Matoso is one of Colombia's largest ferronickel mines, and the Porvenir gabbro, an Upper Jurassic mafic-ultramafic body. The Moho transition has been described as a=outcropping in this area A geospatial analysis of the ophiolites of western Colombia was carried out, where with the help of Landsat and Sentinel sensors, vegetation anomalies, known as "fairy circles", were identified. These vegetation anomalies are usually smaller and the vegetation appears different compared to the fairy circles identified in other countries, but natural hydrogen is still present. In this area an additional peculiarity is added to these anomalies, in the bamboo crops the growth of this plant is affected, with a reduced height in the areas of H2 emanation, suggesting that H2 may be affecting the growth of this plant. In addition, gas measurements were also made on major faults, where the highest H2 concentrations (GA5000 saturation, i.e. 1000 ppm) were found, specifically on the Guabas Pradera fault, in the southern part of the Ginebra ophiolitic complex (Carrillo et al., 2023). The H2 potential in Colombia may be promising, as Cretaceous sediments are present above bedrock, where traps, deposits and seals are likely to be present. For example, in the Cauca Patia basin there are several batholiths that could possibly serve as traps for hydrogen accumulation and in the north there may be a constant generation of hydrogen as it is a hydrated and fractured zone. Carrillo Ramirez, A.; Gonzalez Penagos, F.; Rodriguez, G.; Moretti, I. Natural H2 Emissions in Colombian Ophiolites: First Findings. Geosciences 2023, 13, 358. https:// doi.org/10.3390/geosciences13120358​