Heat production and heat flow in the mantle lithosphere, Slave craton, Canada

• Published in: Physics of the earth and planetary interiors Vol. 123; no. 1; pp. 27 - 44
• Main Authors: Russell, James K., Dipple, G.M., Kopylova, M.G.
• Format: Journal Article
• Language: English
• Published: Elsevier B.V 01-03-2001
• Subjects: Craton; Inversion; Mantle; P– T array; Radiogenic heat production; P– T array; Craton; Model; Radiogenic heat production; Inversion; Mantle
• ISSN: 0031-9201; 1872-7395
• DOI: 10.1016/S0031-9201(00)00201-6

Thermobarometric data for mantle xenoliths from a kimberlite pipe in the NWT, Canada are used to constrain the thermal properties of the lithospheric mantle underlying the Slave craton. We derive an analytical expression for a steady-state conductive mantle geotherm that is independent of the geometry and thermal properties of the crust. The model has an upper boundary coincident with the MOHO at a depth
Z
m and has temperature
T
m and heat flow
q
m. The mantle is assumed to have constant radiogenic heat production (
A) and we allow for a temperature-dependent thermal conductivity [
K(
T)=
Ko(1+
B(
T−
T
m))]. Inverting the thermobarometric data through the model geotherm gives limiting values for mantle heat production (
A) and bounds on the temperature dependence of
K (e.g.
B) that are consistent with the mantle
P–
T array. We characterize the Slave lithospheric mantle in terms of three critical parameters
q
m (mW
m
−2),
A (μW
m
−3),
T
m (°C). The optimal solution has values [15.1, 0.012, 455]. This characterization of thermal state of the Slave mantle is based mainly on petrological data and is not biased by assumptions about crustal thermal properties. Our analysis shows that a substantial range of parameter values can be used to describe the data accurately and the two bounding solutions are [24.2, 0.088, 296] and [12.3, 0, 534], respectively. However, model parameters are strongly correlated and this precludes the arbitrary selection of values of [
q
m,
A,
T
m] from these ranges.