A detrital record of lower oceanic crust exhumation within a Miocene slow-spreading ridge: Macquarie Island, Southern Ocean

2010 ◽  
Vol 123 (1-2) ◽  
pp. 255-273 ◽  
Author(s):  
R. A. Portner ◽  
M. J. Murphy ◽  
N. R. Daczko
Keyword(s):  
Southern Ocean ◽  
Oceanic Crust ◽  
Spreading Ridge ◽  
Macquarie Island ◽  
Slow Spreading ◽  
Lower Oceanic Crust

Extremely asymmetric magmatic accretion of oceanic crust at the ends of slow-spreading ridge segments

Geology ◽  
2000 ◽  
Vol 28 (2) ◽  
pp. 179-182 ◽  
Author(s):  
Simon Allerton ◽  
Javier Escartín ◽  
Roger C. Searle
Keyword(s):  
Oceanic Crust ◽  
Spreading Ridge ◽  
Slow Spreading

scholarly journals In situ lower crustal accretion by melt sill injection revealed by seismic layering

2021 ◽  
Author(s):  
Peng Guo ◽  
Satish Singh ◽  
Venkata Vaddineni ◽  
Ingo Grevemeyer ◽  
Erdinc Saygin
Keyword(s):  
Oceanic Crust ◽  
Lower Crust ◽  
Velocity Variation ◽  
Main Process ◽  
Upper Crust ◽  
Crustal Accretion ◽  
Slow Spreading ◽  
Lower Crustal ◽  
Lower Oceanic Crust

Abstract Oceanic crust is formed at mid-ocean spreading centres by a combination of magmatic, tectonic and hydrothermal processes. The crust formed by magmatic process consists of an upper crust generally composed of basaltic dikes and lava flows and a lower crust presumed to mainly contain homogeneous gabbro whereas that by tectonic process can be very heterogeneous and may even contain mantle rocks. Although the formation and evolution of the upper crust are well known from geophysical and drilling results, those for the lower crust remain a matter of debate. Using a full waveform inversion method applied to wide-angle seismic data, here we report the presence of layering in the lower oceanic crust formed at the slow spreading Mid-Atlantic Ridge, ~7-12 Ma in age, revealing that the lower crust is formed mainly by in situ cooling and crystallisation of melt sills at different depths by the injection of magma from the mantle. These layers are 400-600 m thick with alternate high and low velocities, with ± 100-200 m/s velocity variation, and cover over a million-year old crust, suggesting that the crustal accretion by melt sill intrusions beneath the ridge axis is a stable process. We also find that the upper crust is ~400 m thinner than that from conventional travel-time analysis. Taken together, these discoveries suggest that the magmatism plays more important roles in the crustal accretion process at slow spreading ridges than previously realised, and that in-situ lower crustal accretion is the main process for the formation of lower oceanic crust.

Extremely asymmetric magmatic accretion of oceanic crust at the ends of slow-spreading ridge segments

Geology ◽  
2000 ◽  
Vol 28 (2) ◽  
pp. 179 ◽  
Author(s):  
Simon Allerton ◽  
Javier Escartín ◽  
Roger C. Searle
Keyword(s):  
Oceanic Crust ◽  
Spreading Ridge ◽  
Slow Spreading

Dating the Growth of Oceanic Crust at a Slow-Spreading Ridge

Science ◽  
2005 ◽  
Vol 310 (5748) ◽  
pp. 654-657 ◽  
Author(s):  
J. J. Schwartz
Keyword(s):  
Oceanic Crust ◽  
Spreading Ridge ◽  
Slow Spreading
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