## 4 Discussion  
The four multispectral and radar and microwave satellite datasets of LS8, Sentinel-1, PALSAR, and SRTM were used to perform multisource data fusion and roughness analysis, in order to map the Rimaal circular structure. The results indicate that fusing satellite data collected from both the optical and microwave regions of the spectrum adds value over using a single data source. However, despite the benefits of combining optical and microwave data, image fusion techniques are not commonly used in studying and mapping possible impact craters. The actual Rimaal structure could also be a smaller relic of a formerly larger structure that has afterwards been eroded. Noticeable traces of a corroded central peak in the hybrid imagery might imply the old geological age of the Rimaal structure. Prominent central uplifts at impact structures are typically quite susceptible to erosion. At the present time, the interior of the Rimaal structure is mostly filled with quaternary sediments. The shallowness of the structure is believed to be attributed to the amount of sediment layers that have deposited within it by wind and surface runoff during wet pluvial. The fluvial activities of the incoming eastern paleoriver were most likely responsible for a large fraction of these sediments. If the impact origin hypothesis is confirmed, it is expected that the central peak of the structure is buried under layers of Aeolian and fluvial deposits. It is plausible that in its early stage the Rimaal basin held a considerable amount of water that was supplied from the incoming eastern drainage. Accordingly, lacustrine conditions may have prevailed when water was copious in the past. The ponding water may have formed a local lake occupying at least its deepest part. This lake was probably broadly similar to the modern-day Bosumtwi Lake in Ghana. The latter lake is situated within an ancient complex impact crater that is about 10.5 km in diameter [30], equal to that of the Rimaal structure. The principal drainage cutting through the southern wall of the structure would have served as a spillway for the proposed lake. Lakes in rainy warm regions, such as the proposed Rimaal Lake, are known to accumulate organic-rich lacustrine sediments and, thus, are commonly viewed as analogues for other impact structures that contain economic reserves of oil and gas [31; 32]. In fact, meteorite impact craters of comparable size and geologic setting to the Rimaal structure were found to host significant amounts of oil and gas reservoirs worldwide. In the US, for instance, the total annual commercial hydrocarbon production from nine exploited impact structures was estimated to be between USD$5 and USD$16 billion [5]. Among the impact structures that host rich oil and gas fields in the US are the Ames (16 km), Red Wing (9 km), Sierra Madera (~13 km), and the Marquez (~12.5 km). For example, the Red Wing Creek impact structure in North Dakota, one of the most productive oil basins in the US, has an estimated production of 12.7 million barrels of oil, whereas the Ames impact structure in Oklahoma produces about 7200 barrels of oil per day. For gas production, the Sierra Madera in Texas boasts about 122 million m\({}^{3}\) daily. These structures are all formed in sedimentary rocks. In fact, the Sierra Madera and Marquez craters, in particular, resemble that of the Rimaal structure as they both have a comparable size and are formed in Cretaceous Sedimentary rocks with ages of less than 100 million years. Typically, fracturing and brecciation resulting from meteorite impacts can cause significant porosity and permeability of the target rocks [3; 33], therefore, most the likely produce a good quality oil reservoir. Here, the shock deformation and the generation of central uplift caused by the impact would make a substantially productive reservoir if filled with hydrocarbons [34].