Heat Flow Estimates Research Articles

A new RC and g-function hybrid model to simulate vertical ground heat exchangers

This paper presents a new hybrid two-dimensional model to simulate single U-tube ground heat exchangers based on the use of the electrical analogy to model heat transfer within the borehole and thermal response factors (short and long time-step g-functions) to estimate heat flow to the surrounding ground. Unlike other similar models, heat transfer equations are discretized only within the borehole domain, with two nodes for the fluid and two additional nodes for the grouting material, reducing the number of equations as ground temperature nodes are not considered. The substitution of ground nodes with short and long-term g-functions allows the simulation with short time steps keeping the possibility of simulating periods of several years. A complete analysis of the influence of characteristic parameters of the model in terms of the heat conduction path, vertical discretization level and equivalent heat capacity, has been carried out. The model shows a good performance for short simulation time-steps of five minutes for the prediction of both the short-term and long-term response. It has been successfully validated through comparison with a numerical computational fluid dynamic (CFD) reference model, achieving good RMSE values, which were smaller than 0.15 °C for water outlet temperature and borehole surface mean temperature.

Thermal perturbations beneath the incipient Okavango Rift Zone, northwest Botswana

AbstractWe used aeromagnetic and gravity data to investigate the thermal structure beneath the incipient Okavango Rift Zone (ORZ) in northwestern Botswana in order to understand its role in strain localization during rift initiation. We used three‐dimensional (3‐D) inversion of aeromagnetic data to estimate the Curie Point Depth (CPD) and heat flow under the rift and surrounding basement. We also used two‐dimensional (2‐D) power‐density spectrum analysis of gravity data to estimate the Moho depth. Our results reveal shallow CPD values (8–15 km) and high heat flow (60–90 mW m−2) beneath a ~60 km wide NE‐trending zone coincident with major rift‐related border faults and the boundary between Proterozoic orogenic belts. This is accompanied by thin crust (<30 km) in the northeastern and southwestern parts of the ORZ. Within the Precambrian basement areas, the CPD values are deeper (16–30 km) and the heat flow estimates are lower (30–50 mW m−2), corresponding to thicker crust (~40–50 km). We interpret the thermal structure under the ORZ as due to upward migration of hot mantle fluids through the lithospheric column that utilized the presence of Precambrian lithospheric shear zones as conduits. These fluids weaken the crust, enhancing rift nucleation. Our interpretation is supported by 2‐D forward modeling of gravity data suggesting the presence of a wedge of altered lithospheric mantle centered beneath the ORZ. If our interpretation is correct, it may result in a potential paradigm shift in which strain localization at continental rift initiation could be achieved through fluid‐assisted lithospheric weakening without asthenospheric involvement.

Estimates of Thermal Diffusivity and Heat Flow of a Soil in Agreste Pernambucano

Conhecer as caracteristicas termicas do solo e de fundamental importância para entendimento de seus processos fisicos. Este trabalho objetivou estimar o fluxo de calor do solo atraves da lei de Fourier para o transporte de calor e a difusividade termica do solo utilizando seis metodos (fase, amplitude, logaritmo, conducao-conveccao, arco tangente e diferencas finitas) em um solo tipico. Para isto, foram medidas temperaturas nas profundidades de 0,02; 0,08; 0,10; 0,20; 0,30; 0,40; 0,50 m por meio de termopares ao longo dos primeiros dez dias do ano. A eficacia dos metodos foi comprovada atraves de simulacoes deste mesmo perfil de temperatura do solo onde os algoritmos arco tangente e conducao-conveccao apresentaram os melhores resultados e parâmetros estatisticos, enquanto o metodo das diferencas finitas destoou dos demais. Estimativas do fluxo de calor foram realizadas a partir dos dados medidos e dos estimados, correspondendo aos mesmos resultados obtidos para cada um dos metodos em particular. A B S T R A C T Knowing the thermal characteristics of the soil is of fundamental importance for understanding their physical processes. This study aimed to determine soil heat flux through the Fourier's law for the transport of heat and thermal diffusivity of the soil using six methods (phase, amplitude logarithm conduction-convection, and finite differences arctangent) in a soil wild Pernambucano. For this, temperatures were measured at depths of 0.02; 0.08; 0.10; 0.20; 0.30; 0.40; 0.50 m by means of thermocouples during the first ten days of the year. The effectiveness of the methods has been proven through the soil temperature profile simulations where the algorithms arc tangent and driving-convection showed the best results and statistical parameters, while the finite difference method disagreed when compared the other. Heat flux estimates were made from the boundary conditions of the measured data. The best results observed in the surface layers, while the estimated values did not show satisfactory results in deeper layers. Keywords : soil temperature, soil heat capacity, thermal conductivity in the soil.

Characterization of thermal properties of municipal solid waste landfills

Municipal waste landfills represent not only a source of landfill gases, but a source of thermal energy as well. The heat in landfills is generated by physical, chemical and microbiological processes. The goal of our study was to characterize the thermal properties of municipal solid waste (MSW) samples of the given landfill. A new apparatus was designed and constructed to measure heat flow. A systematic test series of 17 discrete measurements was carried out with municipal waste samples of 1.0–1.7m3. The thermal conductivity, heat diffusivity and specific heat capacity of the samples were determined.Analysing the results of the sampling and our experiments it was realized that the theoretical fundaments should be clarified. Two theories were developed for the serial and for the parallel heat flow in three phase disperse systems. The serial and parallel models resulted in different theoretical estimations. The measured thermal conductivity and heat diffusivity were better characterized by the parallel heat flow estimations. The results show that heat can flow parallel in solid, liquid and gas phases. Characterization of thermal properties serves to establish the fundament of heat extraction from municipal waste landfills.

Global resurfacing of Uranus’s moon Miranda by convection

Miranda, an icy moon of Uranus, is one of the most visually striking and enigmatic bodies in the solar system. Three polygonal-shaped regions of intense deformation, dubbed “coronae,” dominate the surface of Miranda. Here we use numerical methods to show that sluggish-lid convection in Miranda’s ice shell, powered by tidal heating, can simultaneously match the global distribution of coronae, the concentric deformation pattern, and the estimated heat flow during formation. The expected rheological conditions in Miranda’s ice shell lead to the development of low-order convection that produces surface deformation patterns similar to those observed. We find that satellite core size strongly controls convection geometry and that loworder convection patterns are much more stable for core radii less than half the satellite radius.

Average Stress Drops of Southern California Earthquakes in the Context of Crustal Geophysics: Implications for Fault Zone Healing

To understand how fault healing processes affect earthquake stress drops, we search for a possible dependency of stress drops on crustal conditions and geophysical parameters. We reanalyze the stress drop values of ~60,000 earthquakes in southern California which were originally determined by Sheareret al. J Geophys Res 111:B06303, (2006) using a spectral method. We modify the dataset to include only stress drops that are derived from at least 10 spectra and with corner frequencies between 3 and 30 Hz, and correct the rupture velocity for increasing S-wave speed with depth. We see no dependence of stress drop on moment magnitude or depth, except for a small, poorly determined increase from 15 to 25 km. We use six crustal geophysics parameters to search for obvious correlations that may explain changes in the mean values of the stress drops: (1) crustal thickness, (2) isostatic gravity, (3) heat flow, (4) shear strain rate, (5) crustal stress regime, and (6) style of faulting. None of the variables reduce the scatter but most can explain up to 10–20 % variations in the mean stress drops. The geographical distribution of the grouped mean stress drops includes very high stress drops near Ridgecrest, eastern California, as well as near fault jogs within the San Andreas Fault system. Low stress drops dominate in trans-tensional regions. Heat flow and GPS-based shear strain rate estimates have the largest influence on stress drop variations. In the range of low to medium heat flow, the stress drops increase with increasing heat flow. In contrast, at high heat flow in thin crust, the stress drops decrease systematically with increasing heat flow. Increasing shear strain rate systematically correlates with decreasing stress drops. The crustal stress regime and style of faulting also influence the stress drops as demonstrated by lower stress drops for north-northeast trending principal horizontal stress and in areas of dip-slip faulting. The mean variations in stress drops with heat flow, stress regime, crustal thickness, and density can be explained in the context of fault healing (grain boundary growth) and corresponding increase in fault zone strength on time scales modulated by the tectonic shear strain rate.

Method for deep temperature estimation with regard to the paleoclimate influence on heat flow

New results of the study of the distorting effect of paleoclimate on the formation of the thermal field of the Earth’s uppermost crust inthe South Urals are presented. We discuss some consequences of taking into account the paleoclimate influence on estimates of deep heat flow and possible applications of these data. The dependence of the heat flow density on the studied depth of boreholes is considered, and deep heat loss and deep temperatures are estimated. A new method for deep temperature estimation is proposed, which takes into account the paleoclimate influence on the heat flow. The method is tested on the available high-quality temperature data for deep boreholes. Deep temperatures to a depth of –10,000m are estimated for the platform part of the Republic of Bashkortostan using the proposed method. Isotherm schemes are constructed for elevations of –5000 and –10,000m below sea level.The necessity of using heat flow values corrected for the paleoclimate influence to estimate the Earth’s thermal state is justified. Some examples illustrate that underestimation of heat flow values measured in shallow boreholes might lead to underestimation of deep temperatures and global heat losses.

A seismic tool to reduce source maturity risk in unexplored basins

Neil Hodgson, Anongporn Intawong, Karyna Rodriguez and Mads Huuse present a powerful new seismic method for estimating heat flow in undrilled basins.

Lunar surface heat flow mapping from radioactive elements measured by Lunar Prospector

An accurate estimate of global surface heat flow is important because it provides strong constraints on interior thermal model and understanding of the thermal state and geologic evolution of the Moon. In this paper, a distribution map of lunar surface heat flow is derived from calibrated Lunar Prospector gamma-ray spectrometer data (K, U and Th abundances). It shows that surface heat flow varies regionally from about 10.6mW/m2 to 66.1mW/m2, which is in the same order of magnitude as previous results. In the calculation, lunar surface heat flow includes the heat flow from the non-uniform distribution of radioactive elements K, U and Th and that from secular cooling of the Moon. The calculation of heat flow from radioactive elements is based on the assumption that the radioactive decay of K, U and Th on the Moon is the same as that on the Earth. The heat flow from secular cooling of the Moon is assumed to be equal to the global average radioactive heat flow. Firstly we construct a relationship between radioactive elements K, U and Th and lunar surface heat flow. The key parameter of the characteristic length scale in the relationship is determined by measured surface heat flow and Th abundances at Apollo 15 and 17 landing sites. Then the distribution of lunar surface heat flow is derived by combining other parameters such as lunar crustal thickness measured by Clementine and lunar crustal density. In addition, correlation analysis of the three radioactive elements is carried out due to the higher resolution of Th abundance and for ease of calculation.

Thermal conductivity of sediments in high-latitude West Siberia

The thermal conductivity of rocks (λ) used previously to estimate heat flow in high-latitude Siberia was assumed to be λ = 1.8–2.0 W/(m⋅K), according to published evidence, but was almost never measured specially. We measured the thermal conductivity of core samples from boreholes drilled in the northeastern West Siberian Plate and in the Yenisei–Khatanga basin in the 1990s, using two advanced instruments: a comparator and a scanner of thermal conductivity. Altogether there were 305 samples of air-dry sediments (λd) from the 1100–4200 m interval of 23 holes, out of which 77 samples were then moistened (λw). The average thermal conductivities of rocks in dry and wet conditions were found to be λd = 1.9 ± 0.2 and λw = 2.6 ± 0.1 W/(m⋅K), respectively. Thus, the true thermal conductivity of sediments, which are saturated with water in this northern area, must be about 20–30% higher than that assumed in the previous heat flow determinations, and the latter are thus underestimated correspondingly. The updates to the thermal conductivity values imply major revision to the existing ideas of the thermal regime in the Siberian high latitudes. Such a serious revision of geothermal data will obviously require a large amount of additional experimental work.

Estimation of terrestrial heat flow from temperature measurements in bottom sediments

Under study is the problem of estimation of the terrestrial heat flow from the temperature measurements in the bottom sediments. The problem is divided into the two subproblems: first, we solve the one-dimensional inverse problem of estimating the heat conductivity λ and, second, compute the heat flow value by solving the direct stationary problem using the just-found value of λ. We develop a sweep method for solving the direct problem which differs from the standard. An optimization approach is used for solving the inverse problem, and the explicit formulas are obtained for computing the gradient of the error functional. We analyze the factors that cause errors in estimating the heat flow. We show that the main contribution to the errors is given by the presence of harmonics with the periods exceeding the temperature monitoring time interval. We show that if the parameters of the harmonics are known then we can calculate some corrections for the obtained value of the heat flow. The results were applied to the data of temperature measurements carried out at the bottom of Lake Teletskoye from June of 2008 to September of 2010. For finding the long- period harmonics, we use the meteorological data about the bottom water temperature from 1968 to 2011. This allowed us to estimate the heat flow through the bottom of Lake Teletskoye as well as the thermal diffusivity in the upper layer of the sediments.

Effective thermal conductivity of heterogeneous rocks from laboratory experiments and numerical modeling

AbstractStudying heat transfer processes in sedimentary crustal rocks requires the correct thermal conductivity of the respective rock type. Often a single value is used for a given rock type, obtained from the measurements on homogenous samples. We demonstrate how variations in rock layering and microfractures on the subcentimeter scale may influence thermal conductivity values at much larger scale. We obtain thermal conductivity images from lab measurements on two different, heterogeneous samples performed with an optical thermal conductivity scanner in two directions. We study different spatial averaging methods for parameterizing the structural heterogeneities and the associated variation of thermal conductivity within the samples. For each of these structural simplifications, we set up a numerical model for a numerical heat transfer experiment in order to determine effective thermal conductivity values in two directions. We compare these values and the mean thermal conductivities obtained from different mixing laws and find that, in heterogeneous rocks, effective and mean thermal conductivity may differ substantially. This may cause significant errors in reservoir‐scale simulations of heat transfer with associated severe consequences for estimated heat flow and temperatures.

Heat flow data from the southeast of South Australia: distribution and implications for the relationship between current heat flow and the Newer Volcanics Province

This paper presents the results of 34 new heat flow estimates taken in 2004 from 16 water bores and 18 petroleum exploration wells in the western Otway Basin. The average estimated heat flow measured across the study area is 65.6 ± 9.4 mW/m2, with a range of 42–90 mW/m2. There are three recognisable sectors within the study area where heat flow is slightly elevated relative to the background levels. These sectors can be broadly classified as Mount Schank (73.5 ± 0.5 mW/m2), Mount Burr (71.2 ± 7.6 mW/m2) and Beachport (78.3 ± 10.4 mW/m2). Thermal conductivity values for each unit involved in heat flow estimation were determined from laboratory measurements on representative core using a divided bar apparatus. Borehole thermal conductivity profiles were then developed in this study by assigning a constant value of conductivity to each geological formation. The process of collecting temperature data involved measuring temperature profiles for 16 water bores using a cable, winch and thermistor, and compiling well completion temperature data from 18 petroleum wells. The precision of temperature data was higher in the water bores (continuous logs) than in the petroleum wells (largely bottom-of-hole temperature estimates). Inversion heat flow modelling suggests heterogeneous heat flow at 6000 m depth, with two zones where vertical heat flow might exceed 90 mW/m2, and several zones where vertical heat flow might be as low as 40 mW/m2. Therefore, while slightly higher surface heat flow does coincide with some of the volcanic centres, heterogeneous basement heat production is a more likely explanation, as there are no heat flow anomalies greater than 5–10 mW/m2 associated with the Pleistocene–Recent Newer Volcanics Province. The distribution of heat flow in south-east South Australia is most simply explained by non-volcanic phenomena.

Influence of recent depositional and tectonic controls on marine gas hydrates in Trujillo Basin, Peru Margin

Abstract The development of bottom simulating reflectors (BSRs) and the gas hydrate stability zone (GHSZ) in continental margins is related to recent depositional and tectonic processes. This interrelation is important for understanding the potential resource of gas hydrate deposits. The purpose of this study is to understand the influence of such activity on the marine gas hydrate system of the seaward extension of the Trujillo Basin, Peru Margin. Here, we analyze near-seafloor heat flow probe data, high-resolution multichannel seismic (MCS) profiles, swath bathymetry and ocean floor observation system (OFOS) images. Based on our results, we identify three main physiographical subregions in the study area: (1) an area with turbidites, continuous BSRs and low-to-moderate near-seafloor heat flow (7–33 mW/m2), (2) an area with sediment waves of turbidity origin, a mix of continuous and patchy BSRs, and moderate near-seafloor heat flow (26–39 mW/m2), (3) an area with extensional faulting, patchy BSRs and moderate-to-high near-seafloor heat flow (52–110 mW/m2). We conclude that sediment flow processes are the result of recent depositional controls, and faulting is the result of recent tectonic activity. Near-seafloor heat flow around chemoherms is moderate. Estimates of BSR-derived heat flow show differences to near-seafloor heat flow. This difference points to advection of fluids occurring at the seafloor. Alive Calyptogena and tube worms were observed in these venting zones. Based on our analysis, we conclude that: (1) recent depositional processes control the development of continuous BSRs and may restrict heat transfer through the GHSZ in the form of fluid venting at the seafloor, (2) recent tectonic processes control the development of patchy BSRs and allow heat transfer through the GHSZ along faults, which is manifested as fluid venting at the seafloor.

Intrinsic errors on cryogenic calorimetry applied to arc welding

This paper discusses the real meaning of the results from cryogenic calorimetry. A new concept of heat input, denominated as effective heat input, is proposed, based on the fact that what is important for welding engineering is the heat that determines the cooling rates and governs the metallurgical transformations. A descriptive model is proposed to explain how heat flows inside a plate to demonstrate that part of the heat leaves the plate before diffusing into it. Experiments using a liquid nitrogen calorimeter, fully automated to minimize intrinsic errors, were carried out to verify the difference in the outcomes when either bead size or plate thickness is a variable in the test. It was concluded that other intrinsic errors persist and the test, as conceived at the moment, can be applied only on comparative manner if all conditions are the same. However, a promising parameter described here as net heat input maybe taken from the test, which would be independent of variables as bead size and plate thickness and more useful for heat flow and metallurgical estimations.

Heat flow and gas hydrate saturation estimates from Andaman Sea, India

Gas hydrate was recovered in the Andaman Sea along the eastern coast of the Andaman Islands during the India National Gas Hydrate Program (NGHP) Expedition-01 at Site NGHP-01-17. Coring confirmed gas hydrate occurs predominantly in discrete volcanic ash layers. Pore water chemistry, electrical resistivity and P-wave velocity logs are used to estimate gas hydrate saturations at Site NGHP-01-17. Gas hydrate saturation estimated from chloride concentrations shows values up to ∼85% of the pore space for distinct ash layers from ∼270 m below seafloor to the base of gas hydrate stability zone (BGHSZ). Gas hydrate saturations estimated from the electrical resistivity and acoustic velocity logs using standard empirical relations and modeling approaches are comparable to each other, but saturations are only ∼20% of the pore space on average. This much lower gas hydrate saturation estimate from the log data is a result of overall reduced resolution of the logging tools relative to the typically 20–30 cm thick hydrate-bearing ash layers. Available 2D multi-channel seismic data were also analyzed and a bottom-simulating reflector (BSR) was imaged along several seismic profiles. The depth of the BSR is more than 600 m along the seismic line crossing Site NGHP-01-17, which makes this one of the deepest BSRs observed worldwide. To understand the unusual depth of the BSR, we mapped its depth and estimated heat flow from the BSR depth using a simple conductive model. BSR-derived heat flow values range from ∼12 to ∼41.5 mW/m2 from the study area and follow the bathymetry trend of dominant North–South ridges and can be explained with the east-ward trending increase in heat-flow toward the current seafloor spreading center. We also modeled the BGHSZ to analyze the linkage between gas hydrate occurrences in the Andaman Sea and its relation to the tectonic activity. Our analysis suggests an extensively variable BGHSZ in the Andaman Sea controlled mainly by overall low geothermal gradients. Consistent local minor variations were observed with lower heat flow values over prominent topographic highs and higher values in valleys/troughs due to focusing and defocusing effects of the topography.

Gas hydrate and associated free gas in the Dongsha Area of northern South China Sea

A large ongoing cold seep, named Jiulong Methane Reef, was discovered in the Dongsha Area of northern South China Sea (SCS) in 2004. To understand links among seafloor methane seepage, subsurface gas hydrate, origin of gas source and structural styles controlling the formation and accumulation of gas hydrate, high resolution multi-channel seismic data were interpreted in this region. Bottom Simulating Reflectors (BSRs), known as the base of gas hydrate stability zone, were identified and mapped. Additionally, seismic attributes, interval velocity model, and acoustic P wave impedance were obtained to better delineate the spatial distribution of gas hydrate. Hydrate-bearing sediments are characterized by weak reflection (i.e. blanking zone) above BSRs, high velocities and relatively small acoustic impedance differences, while enhanced reflection, low frequency, and low velocities beneath BSRs suggest the presence of underlying free gas beneath solid hydrate. A number of faults, mud diapirs and a possible submarine landslide were observed in seismic profiles. Both faults and mud diapirs are useful conduits, allowing methane gas to migrate upward and linking free gas zones beneath BSRs, hydrate zones and seafloor methane seepage. A submarine landslide with a length scale of ∼10 km is observed in a seismic profile. The landslide may trigger dissociation of gas hydrate, accounting for the occurrence of Jiulong Methane Seepage. Seismic observations and estimated heat flow coupled with geochemical analyses suggest that gas source of methane in this region probably originates from mixture of biogenic and thermogenic methane. This study would not only help to understand gas hydrate system in the Dongsha Area, but also provide insights to geological hazards associated with the dissociation of gas hydrate.

Shallow geothermal regime in the Perth Metropolitan Area

Exploration of Perth's geothermal potential has been performed by the Western Australian Geothermal Centre of Excellence (WAGCoE). Detailed vertical temperature and gamma ray logging of 17 Western Australia Department of Water's (DoW) Artesian Monitoring (AM) wells was completed throughout the Perth Metropolitan Area (PMA). In addition, temperature logs from 53 DoW AM wells measured in the 1980s were digitised into LAS format. The logged data are available in the WAGCoE Data Catalogue. Analysis of the gamma ray logs yielded the first estimates of radiogenic heat production in Perth Basin formations. Values by formation ranged between 0.24 and 1.065 μW m−3. The temperature logs provide a picture of true formation temperatures within shallow sediments in the Perth Basin. A three-dimensional model of the temperature distribution was used to produce maps of temperature at depth and on the top of the Yarragadee aquifer. The temperature data were interpreted with a one-dimensional conductive heat model. Significant differences between the model and the observations was indicative of heat moving via non-conductive mechanisms, such as advection or convection. Evidence of non-conductive or advective heat flow is demonstrated in most formations in the region, with significant effects in the aquifers. Average conductive geothermal gradients range from 13°C km−1 to 39°C km−1, with sandstone formations exhibiting average gradients of approximately 25°C km−1, while insulating silt/shale formations show higher average gradients of over 30°C km−1. To produce preliminary heat flow estimates, temperature gradients were combined with thermal conductivities measured elsewhere. The geometric mean heat flow estimates range between 64 mW m−2 to 91 mW m−2, with the standard deviation of the arithmetic mean heat flow ranging between 15 and 23 mW m−2. The study characterises the shallow temperature regime in the Perth Metropolitan Area, which is of direct relevance towards developing commercial geothermal projects.

Heat Flow and Thermal State of the Crust of the Icy Galilean Satellites

The use of lithosphere strength indicators (as for example the effective elastic thickness of the lithosphere or the depth to the brittle-ductile transition) can give clues on the surface heat flow and the thermal state of the ice crust of icy satellites, which in turn has profound implications for the internal evolution, and the possible existence of internal oceans, in these planetary bodies. As shown in this review, this kind of approach has found very high (and possibly recent) surface heat flows for Europa and ancient high heat flows for Ganymede. On the other hand, the heavily cratered of Callisto suggests a cold and inactive outer ice shell throughout the entire history of that body. However, irrespective of the greatly different geology recorded on the surface of the icy Galilean satellites, there is evidence from orbital magnetic observations for internal oceans in all them. By considering heat flow estimates in the context existence of internal oceans, a more complete description of the thermal history of the icy Galilean satellites should emerge.

Martian surface heat production and crustal heat flow from Mars Odyssey Gamma-Ray spectrometry

[1] Martian thermal state and evolution depend principally on the radiogenic heat-producing element (HPE) distributions in the planet's crust and mantle. The Gamma-Ray Spectrometer (GRS) on the 2001 Mars Odyssey spacecraft has mapped the surface abundances of HPEs across Mars. From these data, we produce the first models of global and regional surface heat production and crustal heat flow. As previous studies have suggested that the crust is a repository for approximately 50% of the radiogenic elements on Mars, these models provide important, directly measurable constraints on Martian heat generation. Our calculations show considerable geographic and temporal variations in crustal heat flow, and demonstrate the existence of anomalous heat flow provinces. We calculate a present day average surface heat production of 4.9 ± 0.3 × 10−11 W · kg−1. We also calculate the average crustal component of heat flow of 6.4 ± 0.4 mW · m−2. The crustal component of radiogenically produced heat flow ranges from <1 mW · m−2 in the Hellas Basin and Utopia Planitia regions to ∼13 mW · m−2 in the Sirenum Fossae region. These heat production and crustal heat flow values from geochemical measurements support previous heat flow estimates produced by different methodologies.