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Seismic Crustal Structure and Morphotectonic Features Associated With the Chain Fracture Zone and Their Role in the Evolution of the Equatorial Atlantic Region
Author(s) -
Marjanović Milena,
Singh Satish C.,
Gregory Emma P. M.,
Grevemeyer Ingo,
Growe Kevin,
Wang Zhikai,
Vaddineni Venkata,
Laurencin Muriel,
Carton Hélène,
Gómez de la Peña Laura,
Filbrandt Christian
Publication year - 2020
Publication title -
journal of geophysical research: solid earth
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.983
H-Index - 232
eISSN - 2169-9356
pISSN - 2169-9313
DOI - 10.1029/2020jb020275
Subject(s) - geology , seismology , lithosphere , ridge , fracture zone , transform fault , bathymetry , classification of discontinuities , mid ocean ridge , convergent boundary , ridge push , oceanic crust , geophysics , paleontology , tectonics , subduction , oceanography , mathematical analysis , mathematics
Oceanic transform faults and fracture zones (FZs) represent major bathymetric features that keep the records of past and present strike‐slip motion along conservative plate boundaries. Although they play an important role in ridge segmentation and evolution of the lithosphere, their structural characteristics, and their variation in space and time, are poorly understood. To address some of the unknowns, we conducted interdisciplinary geophysical studies in the equatorial Atlantic Ocean, the region where some of the most prominent transform discontinuities have been developing. Here we present the results of the data analysis in the vicinity of the Chain FZ, on the South American Plate. The crustal structure across the Chain FZ, at the contact between ∼10 and 24 Ma oceanic lithosphere, is sampled along seismic reflection and refraction profiles. We observe that the crustal thickness within and across the Chain FZ ranges from ∼4.6–5.9 km, which compares with the observations reported for slow‐slipping transform discontinuities globally. We attribute this presence of close to normal oceanic crustal thickness within FZs to the mechanism of lateral dike propagation, previously considered to be valid only in fast‐slipping environments. Furthermore, the combination of our results with other data sets enabled us to extend the observations to morphotectonic characteristics on a regional scale. Our broader view suggests that the formation of the transverse ridge is closely associated with a global plate reorientation that was also responsible for the propagation and for shaping lower‐order Mid‐Atlantic Ridge segmentation around the equator.