Morfoestrutura da Cordilheira Meso-Oceânica entre as Zonas de Fraturas Marathon e 8°48'N

Abstract

The Mid-Atlantic Ridge is a highly complex geotectonic region, essential for understanding the evolution of oceanic crust and the processes associated with divergent plate tectonics. This study analyzed approximately 400 km of the ridge’s axial segment, between the Marathon Fractures Zone and 8°48’N, with depths ranging from 1,600 m to 6,000 m, using bathymetric, gravimetric, and seismicity data. The objective was to investigate the interaction between magmatism and tectonism in shaping the oceanic relief, with an emphasis on ridge-transform intersections (RTIs) and non-transform discontinuities (NTDs). The northern portion of the area, located above the Vema Fracture Zone, was divided into two supersegments, 12°N and 11°N, the latter further subdivided into the 11°55'N and 11°20'N segments. The southern portion presented the 9°N and 10°N supersegments, segmented by second-order discontinuities. The results indicate that these segmentations exhibit peculiar morphological and geophysical characteristics but share similar formation and evolution processes, highlighting how the interaction between magmatism and tectonism directly influences the morphotectonic configuration of the Mid-Atlantic Ridge. Structures such as detachment faults in elevated inside corners play a crucial role in generating asymmetries, reflecting the impact of lithospheric decoupling in slow-spreading regions with evidence of reduced magmatic flow. Additionally, NTDs promote reduced or absent magmatism, exposing massifs and rocks with altered rheology, distinct from those observed in the abyssal hills of the supersegments. These features, in particular, are favorable for fluid percolation and the formation of hydrothermal systems, standing out as priority areas for future investigations, especially at the intersection of the 11°20'N segment with the Vema transform fault.