Mapping structures obscured by sediments of the southern Hanoi basin using gravity data

The tectonic and depositional history of the Hanoi basin is intricately shaped by the India-Eurasia collision, resulting in a complex subsurface structure that remains of significant interest for geophysical studies. In this research, classical and recent edge enhancement filters are applied to map subsurface features in the sediment-covered southern Hanoi basin. Additionally, the tilt-depth technique is employed to estimate the depth of subsurface structures in the study area. The interpretation revealed several subsurface structures, most of which have depths ranging from 0.9 km to 4 km. The subsurface features revealed by the enhancement filters show that the region's structural trend is generally NW-SE, aligning with significant faults within the Red River fault zone, including the Song Chay and Song Lo. According to the tilt-depth estimates, the faults are identified at intermediate to deeper depths, reflecting geological displacements during the Oligocene and early Miocene that caused the Indochina geoblock to move about 700 km southeast along the Red River fault zone. Our detailed analysis also showed the Hanoi basin forms the landward extension of the Song Hong basin. The findings not only align with established tectonic features but also underscore the effectiveness of advanced filtering techniques, particularly the improved edge detector, in refining subsurface mapping within complex geological settings.