Beo v1.0: Numerical model of heat flow and low-temperature thermochronology in hydrothermal systems

Abstract

Low-temperature thermochronology can provide records of the thermal history of the upper crust and can be a valuable tool to quantify the history of hydrothermal systems. However, existing model codes of heat flow around hydrothermal systems do not include low-temperature thermochronology. Here I present a new model code that simulates thermal history 5 around hydrothermal systems on geological timescales. The modelled thermal histories are used to calculate apatite (U-Th)/He (AHe) ages, which is a thermochronometer that is sensitive to temperatures up to 70°C. The modelled AHe ages can be compared to measured values in surface outcrops or borehole samples to quantify the history of hydrothermal activity. Heat flux at the land surface is based on equations of latent and sensible heat flux, which allows more realistic land surface and spring temperatures than models that use simplified boundary conditions. Instead of simulating fully coupled fluid and heat 10 flow, the code only simulates advective and conductive heat flow, with the rate of advective fluid flux specified by the user. This relatively simple setup is computationally efficient and allows running larger numbers of models to quantify model sensitivity and uncertainty. Example case studies demonstrate the sensitivity of hot spring temperatures to the depth, width and angle of permeable fault zones, and the effect of hydrothermal activity on AHe ages in surface outcrops and at depth.

Using Thermal Springs to Quantify Deep Groundwater Flow and Its Thermal Footprint in the Alps and a Comparison With North American Orogens

“…Thermal springs are the most visible surface expression of deep groundwater flow in orogens. Data on spring discharge and temperature offer opportunities to quantify deep groundwater flow and its thermal effects (Luijendijk, 2019; Manga, 2001). The only analysis of thermal springs in orogens known to us covers North America (Ferguson & Grasby, 2011).…”

Beo v1.0: numerical model of heat flow and low-temperature thermochronology in hydrothermal systems

“…Code availability. The source code of Beo version 1.0 was published at Zenodo (Luijendijk, 2018) and is accessible online (https://doi.org/10.5281/zenodo.2527844). The source code is also available on a GitHub repository (https://github.com/ ElcoLuijendijk/beo, last access: 2 August 2019; Luijendijk, 2019).…”

Determining the Lifespan of Hydrothermal Systems Using Thermochronology and Thermal Modeling

“… Model set up for hydrothermal modeling using Beo v1.0 (Luijendijk, 2019). The approach models advective and conductive upwards heat flow along a single fault plane and within a defined finite element mesh (Luijendijk, 2019). Variables such as fault angle, depth of circulation, fault width, water flux, porosity, exhumation rate, geothermal gradient and surface temperature are outlined with the necessary references (Allen et al., 2006; Black, 1987; Liu et al., 2007; Seipold & Huenges, 1998; Werner et al., 2019).…”