The magmatic and tectonic role in spreading styles at ridge–transform intersections between the Marathon and Vema Transform Faults
Abstract
The Mid-Atlantic Ridge (MAR) between the Marathon and Vema Transform Faults exhibits contrasting tectono-magmatic domains shaped by transform faults, non-transform discontinuities, and detachment faults. This study analyzes the 11 • N and 12 • N supersegments using high-resolution multibeam bathymetry and crustalthickness estimates from filtered RMBA inversion. We examine how variations in crustal thickness and lithospheric structural configuration along the ridge axis relate to segmentation by non-transform discontinuities and to morphological asymmetries at ridge-transform intersections in this sector of the MAR. The 11 • N supersegment, divided into the 11 • 55′N and 11 • 20′N segments, shows stronger tectonic segmentation than the 12 • N supersegment, with enhanced along-axis structural relief and locally rugged axial-valley morphologies. These characteristics are associated with asymmetric faulting patterns consistent with spatially variable tectonic extension and spatially discontinuous volcanic features. In contrast, the 12 • N supersegment shows segment-scale crustal-thickness maxima concentrated near the axial domain, while superficial volcanic expression is less continuously developed near the major discontinuities, consistent with increased tectonic accommodation in those areas. Detachment-related terrains are preferentially concentrated near ridge-transform intersections and non-transform discontinuities. In this supersegment, higher crustal-thickness estimates are concentrated within the axial domain and segment center, whereas domains adjacent to RTIs and NTDs are characterized by detachment-related terrains and reduced continuity of surficial volcanic construction. At the ridge-transform intersections, contrasting behaviors are observed. The Marathon ridge-transform intersection, located at the northern end of the 12 • N supersegment, exhibits limited recent volcanic expression and short-lived and spatially restricted faulting. In contrast, the Vema RTI, at the southern end of the 11 • N supersegment, is dominated by extensive detachment faulting and a prominent massif, consistent with a more mature detachment-dominated configuration. Overall, the contrasting segmentation of the 11 • N and 12 • N supersegments reflects systematic along-axis variations in magmatic contribution and lithospheric structural configuration, particularly near ridge-transform intersections and non-transform discontinuities.
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BibTeX
@article{oliveira2026magmatic,
title = {{The magmatic and tectonic role in spreading styles at ridge–transform intersections between the Marathon and Vema Transform Faults}},
author = {Patrícia Reis Alencar Oliveira and Márcia Maia and Moab Paxedes Gomes and Heliásio Augusto Simões},
journal = {Marine Geology},
year = {2026},
month = nov,
doi = {10.1016/j.margeo.2026.107768},
url = {https://hal.science/hal-05848549v1},
note = {CC BY-NC-ND 4.0},
}
RIS
TY - JOUR
TI - The magmatic and tectonic role in spreading styles at ridge–transform intersections between the Marathon and Vema Transform Faults
AU - Patrícia Reis Alencar Oliveira
AU - Márcia Maia
AU - Moab Paxedes Gomes
AU - Heliásio Augusto Simões
PY - 2026
DA - 2026/11/02
JO - Marine Geology
DO - 10.1016/j.margeo.2026.107768
UR - https://hal.science/hal-05848549v1
AB - The Mid-Atlantic Ridge (MAR) between the Marathon and Vema Transform Faults exhibits contrasting tectono-magmatic domains shaped by transform faults, non-transform discontinuities, and detachment faults. This study analyzes the 11 • N and 12 • N supersegments using high-resolution multibeam bathymetry and crustalthickness estimates from filtered RMBA inversion. We examine how variations in crustal thickness and lithospheric structural configuration along the ridge axis relate to segmentation by non-transform discontinuities and to morphological asymmetries at ridge-transform intersections in this sector of the MAR. The 11 • N supersegment, divided into the 11 • 55′N and 11 • 20′N segments, shows stronger tectonic segmentation than the 12 • N supersegment, with enhanced along-axis structural relief and locally rugged axial-valley morphologies. These characteristics are associated with asymmetric faulting patterns consistent with spatially variable tectonic extension and spatially discontinuous volcanic features. In contrast, the 12 • N supersegment shows segment-scale crustal-thickness maxima concentrated near the axial domain, while superficial volcanic expression is less continuously developed near the major discontinuities, consistent with increased tectonic accommodation in those areas. Detachment-related terrains are preferentially concentrated near ridge-transform intersections and non-transform discontinuities. In this supersegment, higher crustal-thickness estimates are concentrated within the axial domain and segment center, whereas domains adjacent to RTIs and NTDs are characterized by detachment-related terrains and reduced continuity of surficial volcanic construction. At the ridge-transform intersections, contrasting behaviors are observed. The Marathon ridge-transform intersection, located at the northern end of the 12 • N supersegment, exhibits limited recent volcanic expression and short-lived and spatially restricted faulting. In contrast, the Vema RTI, at the southern end of the 11 • N supersegment, is dominated by extensive detachment faulting and a prominent massif, consistent with a more mature detachment-dominated configuration. Overall, the contrasting segmentation of the 11 • N and 12 • N supersegments reflects systematic along-axis variations in magmatic contribution and lithospheric structural configuration, particularly near ridge-transform intersections and non-transform discontinuities.
SN - 0025-3227
ER -