scholarly journals Magma reservoir evolution at fast-spreading mid-ocean ridges

2021 ◽  
Author(s):  
Johan Lissenberg ◽  
Matthew Loocke ◽  
George Cooper ◽  
Christopher MacLeod
Keyword(s):  
Magma Reservoir ◽  
Ocean Ridges ◽  
Fast Spreading ◽  
Reservoir Evolution

scholarly journals Processes in Crystal Mushes Under Fast-Spreading Mid-Ocean Ridges

2020 ◽  
Author(s):  
Juergen Koepke ◽  
Dominik Mock ◽  
Chao Zhang
Keyword(s):  
Ocean Ridges ◽  
Fast Spreading

Unveiling the volcanic evolution of the Mohns Ridge

2021 ◽  
Author(s):  
Håvard Stubseid ◽  
Anders Bjerga ◽  
Haflidi Haflidason ◽  
Rolf Birger Pedersen
Keyword(s):  
Autonomous Underwater Vehicles ◽  
Volcanic Eruptions ◽  
Integrated Approach ◽  
Hydrothermal Systems ◽  
Ocean Ridges ◽  
Spreading Ridges ◽  
Geological Evolution ◽  
Fast Spreading ◽  
Slow Spreading ◽  
Resolution Dataset

<p>Volcanic eruptions are far less common along slow-spreading ridges compared to fast-spreading ridges. Consequently, knowledge of the volcanic rejuvenation along close to 1/3 of the global mid-ocean ridges is poorly constrained. To determine the temporal evolution of the rift valley of one of the slowest spreading-ridges in the world, the Mohns Ridge in the Norwegian-Greenland Sea, we have interpreted more than 3000 km of sub-bottom profiles. Sedimentation rates derived from several core locations along the ridge are used to calculate the age of the underlying volcanic crust. Here we present a framework for understanding the geological evolution of rift valleys of slow-spreading ridges using an integrated approach combining geological and geophysical data. The high-resolution dataset acquired using autonomous underwater vehicles, cover more than 50% of the 575 km long Mohns Ridge. The results unravel large variation in sediment thickness inside the central rift area, from exposed basalts to several meters of sediments, within only a few hundreds of meters. Studied sub-bottom profiles reveal active volcanism in the deepest parts of the ridge, areas thought to be inactive, surrounded by significantly older crust covered in meters of sediments. We find that all axial volcanic ridge systems (AVRs) in our area completely renewed their surface within the last 30-50 ka. Detailed volcanological investigation of the central parts of an AVR reveal at least 72 individual eruptions during the last 20 ka ranging in size from 1.2x10<sup>3 </sup>m<sup>2</sup> - 2.6 x10<sup>5</sup> m<sup>2</sup>. These estimates have been verified with visual observations and sampling using an ROV. Our estimates indicate that more than 230 eruptions are required to renew the surface of an average AVR. Based on the acquired age assessments a volcanic eruption is anticipated to occur approximately every 200 years. Volcanic renewal is a first order control on the lifetime of magmatically driven hydrothermal systems.</p>

scholarly journals Numerical model of crustal accretion and cooling rates of fast-spreading mid-ocean ridges

2013 ◽  
Vol 6 (2) ◽  
pp. 2429-2456
Author(s):  
P. Machetel ◽  
C. J. Garrido
Keyword(s):  
Thermal State ◽  
Variable Viscosity ◽  
Experimental Petrology ◽  
Closure Temperature ◽  
Cooling Rates ◽  
Ridge Structure ◽  
Crustal Rocks ◽  
Temperature Range ◽  
Ocean Ridges ◽  
Fast Spreading

Abstract. We designed a thermo-mechanical model for fast spreading mid-ocean ridge with variable viscosity, hydrothermal cooling, latent heat release, sheeted dyke layer, and variable melt intrusion possibilities. The model allows to take into account several accretion possibilities as: the "gabbro glacier" (G), the "sheeted sills" (S) or the "mixed shallow and MTZ lenses" (M). Viscosity contrasts of 2 to 3 orders of magnitude between the hot and cold phases have been tested. We also explored hydrothermal cooling according to various cracking temperatures for crustal rocks. Hence, the model allows exploring various near ridge motions and thermal patterns that induce various cooling histories for gabbros. According to the assumed opening-closure temperature range, the cooling rates sample the near-ridge structure or record areas farther from the ridge. As an analogy to experimental petrology we called ICR the cooling rates sampled near the ridge and SRC the cooling rates sampled far from the ridge where the flow tends to laminar and conductive patterns. The results emphasize that the cooling rates may significantly depend on the choice of this opening-closure temperature range. The results show that numerical modeling of thermo-mechanical properties of the lower crust's may bring information to study the hypotheses related to the ridge accretion structure, hydrothermal cooling and thermal state at the fast-spreading ridges.

Sign in / Sign up

Export Citation Format

Share Document