Heat flow study at the Chinese Continental Scientific Drilling site: Borehole temperature, thermal conductivity, and radiogenic heat production

Abstract

[1] The Chinese Continental Scientific Drilling (CCSD) Project offers a unique opportunity for studying the thermal regime of the Dabie-Sulu ultrahigh-pressure metamorphic belt. In this paper, we report measurements of borehole temperature, thermal conductivity, and radiogenic heat production from the 5158 m deep main hole (CCSD MH). We have obtained six continuous temperature profiles from this borehole so far. The temperature logs show a transient mean thermal gradient that has increased from 24.38 to 25.28 K km À1 over a period of about 1.5 years. We measured thermal conductivities and radiogenic heat productions on more than 400 core samples from CCSD MH. The measured thermal conductivities range between 1.71 and 3.60 W m À1 K À1 , and the radiogenic heat productions vary from 0.01 mW m À3 to over 5.0 mW m À3 , with a mean value of 1.23 ± 0.82 mW m À3 for the upper 5-km layer of the crust. The heat productions in CCSD MH appear to be more rock-type than depth-dependent and, over the depth range of CCSD MH, do not fit the popular model of heat production decreasing exponentially with increasing depth. The measured heat flow decreases with depth from $75 mW m À2 near the surface to $66 mW m À2 at a depth of 4600 m. High heat flow anomalies occur at $1000 and $2300 m, and low anomalies occur at 3300-4000 m. A preliminary two-dimensional numerical model suggests that both radiogenic heat production and thermal refraction due to structural heterogeneity are at least partially responsible for the vertical variation of heat flow in CCSD MH.

Evaluation of common mixing models for calculating bulk thermal conductivity of sedimentary rocks: Correction charts and new conversion equations

“…The less time-consuming optical scanning technique (OS) is, since introduced in the 1990s by Y. Popov, recently the most frequently used method to measure TC for large sample sets. This method was applied successfully to crystalline rocks (e.g., He et al, 2008;Popov et. al., 1999) as well as to sedimentary rocks (e.g., Clauser, 2006;Fuchs and Förster, 2010;Hartmann et al, 2005Hartmann et al, , 2008Homoth et al, 2008;Liu et al, 2011;Majorowicz et al, 2008;Mottaghy et al, 2005;Norden and Förster, 2006;Orilski et al, 2010;Popov et al, 1995Popov et al, , 2003Popov et al, , 2010Popov et al, , 2011Schütz et al, 2012).…”

Heat Flow and Hydrologic Characteristics at the AND-1B borehole, ANDRILL McMurdo Ice Shelf Project, Antarctica

“…Of these, the line-source method of Horner (1951), as implemented by Lachenbruch and Brewer (1959), is relatively precise even though it does contain an inherent bias to lower temperatures that reduces accuracy slightly (Beardsmore and Cull, 2001). A detailed study describing the proper application of this method has recently been reported by He et al (2008).…”

Characteristics of Heat Flow and Lithospheric Thermal Structure in the Junggar Basin, Northwestern China

“…Since the 1990s, the optical scanning technique [15] was widely applied to measurements of rock thermal conductivity, which has advantages such as high work efficiency, non contact manner, direct measurements on rock-cores (no need to make samples) and being able to estimate anisotropy and inhomogeneity of rocks. So far the successful cases of its utility includes the Vorotilovo deep borehole at the East Europe platform [28] , deep borehole at the Kola peninsula of Russia [29] , and deep borehole at the Sulu-Dabie area of China [30] .…”