Predictions of hydrothermal alteration within near-ridge oceanic crust from coordinated geochemical and fluid flow models

• Published in: Journal of volcanology and geothermal research 2001-10, Vol.110 (3-4), p.319-341
• Main Authors: Wetzel, Laura Reiser, Raffensperger, Jeff P., Shock, Everett L.
• Format: Article
• Language: English
• Subjects: Aging of materials; Crystalline rocks; Earth sciences; Earth, ocean, space; Exact sciences and technology; Finite element method; Flow of fluids; Geochemistry; heat flow; Heat transfer; Hydrology; hydrothermal alteration; Igneous and metamorphic rocks petrology, volcanic processes, magmas; oceanic crust; Porosity; Thermal effects
• ISSN: 0377-0273; 1872-6097
• DOI: 10.1016/S0377-0273(01)00215-3

Coordinated geochemical and hydrological calculations guide our understanding of the composition, fluid flow patterns, and thermal structure of near-ridge oceanic crust. The case study presented here illustrates geochemical and thermal changes taking place as oceanic crust ages from 0.2 to 1.0Myr. Using a finite element code, we model fluid flow and heat transport through the upper few hundred meters of an abyssal hill created at an intermediate spreading rate. We use a reaction path model with a customized database to calculate equilibrium fluid compositions and mineral assemblages of basalt and seawater at 500bars and temperatures ranging from 150 to 400°C. In one scenario, reaction path calculations suggest that volume increases on the order of 10% may occur within portions of the basaltic basement. If this change in volume occurred, it would be sufficient to fill all primary porosity in some locations, effectively sealing off portions of the oceanic crust. Thermal profiles resulting from fluid flow simulations indicate that volume changes along this possible reaction path occur primarily within the first 0.4Myr of crustal aging.