Heterogeneous and asymmetric crustal accretion : new constraints from multibeam bathymetry and potential field data from the Rainbow area of the Mid-Atlantic Ridge (36°15'N)
Canales, J. Pablo
Dunn, Robert A.
Sohn, Robert A.
MetadataShow full item record
KeywordOceanic detachment faults; Geomorphology; Crustal accretion; Slow-spreading ridges; Nontransform discontinuities; Gravity anomalies
At slow-spreading mid-ocean ridges, crustal accretion style can vary significantly along and across ridge segments. In magma-poor regions, seafloor spreading can be accommodated largely by tectonic processes, however, the internal structure and formation mechanism of such highly tectonized crust are not fully understood. We analyze multibeam bathymetry and potential field data from the Rainbow area of the Mid-Atlantic Ridge (35°40'N–36°40'N), a section of the ridge that shows diverse accretion styles. We identify volcanic, tectonized and sedimented terrain and measure exposed fault area to estimate the tectonic strain, T, and the fraction of magmatic accretion, M. Estimated T values range from 0.2–0.4 on ridge segments to 0.6-0.8 at the Rainbow nontransform discontinuity (NTD). At segment ends T is asymmetric, reflecting asymmetries in accretion rate, topography and faulting between inside and outside offset corners. Detachment faults have formed preferentially at inside corners, where tectonic strain is higher. We identify at least two oceanic core complexes on the fossil trace of the NTD, in addition to the Rainbow massif, which occupies the offset today. A gravity high and low magnetization suggest that the Rainbow massif, which hosts a high-temperature hydrothermal system, was uplifted by a west dipping detachment fault. Asymmetric plate ages indicate localization of tectonic strain at the inside corners and migration of the detachment toward and across the ridge axis, which may have caused emplacement of magma into the footwall. Hydrothermal circulation and heat extraction is possibly favored by increased permeability generated by fracturing of the footwall and deep-penetrating second-generation faults.
Author Posting. © American Geophysical Union, 2015. This article is posted here by permission of American Geophysical Union for personal use, not for redistribution. The definitive version was published in Geochemistry, Geophysics, Geosystems 16 (2015): 2994–3014, doi:10.1002/2015GC005743.
Suggested CitationArticle: Paulatto, Michele, Canales, J. Pablo, Dunn, Robert A., Sohn, Robert A., "Heterogeneous and asymmetric crustal accretion : new constraints from multibeam bathymetry and potential field data from the Rainbow area of the Mid-Atlantic Ridge (36°15'N)", Geochemistry, Geophysics, Geosystems 16 (2015): 2994–3014, DOI:10.1002/2015GC005743, https://hdl.handle.net/1912/7695
Showing items related by title, author, creator and subject.
Hosford, Allegra (Massachusetts Institute of Technology and Woods Hole Oceanographic Institution, 2001-09)Half of the ocean crust is formed at spreading centers with total opening rates less than 40 km/Myr. The objective of this Thesis is to investigate temporal variations in active ridge processes and crustal aging at ...
Jaroslow, Gary E. (Massachusetts Institute of Technology and Woods Hole Oceanographic Institution, 1996-12)The objective of this Thesis was to interpret the structural development of slowspreading ridge segments by: 1) delineating the nature, magnitude, and relative importance of primary tectonic and volcanic processes that ...
Central Anomaly Magnetization High documentation of crustal accretion along the East Pacific Rise (9°55′–9°25′N) Williams, Clare M.; Tivey, Maurice A.; Schouten, Hans A.; Fornari, Daniel J. (American Geophysical Union, 2008-04-09)Near-bottom magnetic data collected along the crest of the East Pacific Rise between 9°55′ and 9°25′N identify the Central Anomaly Magnetization High (CAMH), a geomagnetic anomaly modulated by crustal accretionary processes ...