In this work, we report new chemical and isotopic data (³He/⁴He, δ¹³C_CO2, δ¹³C_CH4, and δD_CH4) from poorly or previously unstudied hydrothermal and magmatic gases that are emitted along the eastern coast of the Baja California Peninsula (BCP). High ³He/⁴He values (up to ~7 Ra) characterize the magmatic gases, while lower ratios (≤1.6 Ra) characterize hydrothermal springs. We infer that the mantle beneath the BCP could be Mid‐ocean‐ridge basalt (MORB)‐likes, as in the rift within the Gulf of California, or it may reflect contamination from C‐rich sediment during paleo‐subduction of the Farallon plate. During their ascent, through the crust, mantle/magmatic gases mix with CO₂‐ and ⁴He‐rich fluids, thus forming CO₂‐rich hydrothermal gases. These hydrothermal gases undergo partial dissolution of CO₂ in shallow waters under different temperature and pH conditions, which further modifies their composition. Thermogenic and possibly abiogenic sources of methane are present only in magmatic gases from the BCP. Secondary methane oxidation (microbial/inorganic) processes are proposed for some hydrothermal gases, which are extremely enriched in heavy isotopes. Finally, we argue that the hydrothermal gases that are emitted from the BCP have variable percentages of mantle contribution, indicating the presence of lithospheric faults enhancing the rise of mantle fluids also in areas where volcanism is absent.

We present results of our simulation study of the effects of the depth (top of the magma chamber at 5–10 km) and volume (1000–1400 km³) of the primary heat source beneath the Los Humeros caldera. The thermal gradient in the vicinity of the magma chamber calculated from the temperature excess (difference between the simulated and the initial temperatures prior to emplacement of the magma) is more sensitive to its depth of intrusion than to its volume. This relationship was quantified from multiple linear regression equations. The temperature excess at 2–3 km depth due to the emplacement of magma and its conductive cooling is also more dependent on the chamber depth than on its volume. Therefore, in the study of calderas, volcanoes, and geothermal fields, constraining the chamber depth is more important than its volume. Similarly, comparison of the thermal regime inferred along vertical and horizontal profiles shows the importance of solving the thermal transport equations in three dimensions instead of one or two dimensions.

The La Primavera caldera lies close to the triple junction of the Tepic-Zacoalco, Colima, and Chapala rifts in the western part of the Mexican Volcanic Belt. It is a promising geothermal field with 13 deep wells already drilled. We calculated solute geothermometric temperatures (Na–K, Na–Li, and SiO₂) from the chemistry of geothermal water samples; determined values are generally between 99°C and 202°C for springs and between 131°C and 298°C for wells. Thermal modelling is an important geophysical tool as documented in the study of this and other Mexican geothermal areas. Using the computer program TCHEMSYS, we report new simulation results of three-dimensional (3-D) thermal modelling of the magma chamber underlying this caldera through its entire eruptive history. Equations (quadratic fit) describing the simulated temperatures as a function of the age, volume and depth of the magma chamber are first presented; these indicate that both the depth and the age of the magma chamber are more important parameters than its volume. A comparison of 3-D modelling of the La Primavera and Los Humeros calderas also shows that the depth of the magma chamber is more important than its volume. The best model for the La Primavera caldera has 0.15 million years as the emplacement age of the magma chamber, its top at a depth of 4 km, and its volume as 600 km³. Fresh magma recharge events within the middle part of the magma chamber were also considered at 0.095, 0.075, and 0.040 Ma. The simulation results were evaluated in the light of actually measured and solute geothermometric temperatures in five geothermal wells. Future work should involve a smaller mesh size of 0.050 or 0.10 km on each side (instead of 0.25 km currently used) and take into account the topography of the area and all petrogenetic processes of fractional crystallization, assimilation, and magma mixing as well as heat generation from natural radioactive elements.

Solar and geothermal energies are considered cleaner and more useful energy sources that can be used to avoid the negative environmental impacts caused by burning fossil fuels. Several works have reported air-conditioning systems that use solar energy coupled to geothermal renewable energy as a thermal source. In this study, an Absorption Air-Conditioning System (AACS) used sodium hydroxide-water (NaOH-H₂O) instead of lithium bromide-water to reduce the cost. Low enthalpy geothermal heat was derived from two shallow wells, 50 and 55 m deep. These wells are of interest due to the thermal recovery (temperature vs. time) of 56.2 °C that was possible at the maximum depth, which can be used for the first stage of the process. These wells were coupled with solar energy as a geothermal energy application for direct uses such as air-conditioning systems. We studied the performance of an absorption cooling system operating with a NaOH-H₂O mixture and using a parabolic trough plant coupled with a low enthalpy geothermal heat system as a hybrid heat source, as an alternative process that can help reduce operating costs and carbon dioxide emissions. The numerical heat transfer results showed the maximum convective heat transfer coefficient, as function of fluid velocity, and maximum temperature for a depth higher than 40 m. The results showed that the highest temperatures occur at low fluid velocities of less than or equal to 5.0 m/s. Under these conditions, reaching temperatures between 51.0 and 56.2 °C in the well was possible, which is required of the geothermal energy for the solar energy process. A water stream was used as the working fluid in the parabolic trough collector field. During the evaluation stage, the average experimental storage tank temperature achieved by the parabolic trough plant was 93.8 °C on October 23 and 92.9 °C on October 25, 2017. The numerical simulation used to evaluate the performance of the absorption cycle used a generator temperature of 90 °C, a condenser and absorber temperature at 35 °C, and an evaporator temperature of 10 °C. The Coefficient of Performance was calculated as 0.71 under design conditions.