Thermal Conductivities and Thermal Diffusivities Measured in Cores

from Two Boreholes Drilled in the Hurd Peninsula of Livingston Island

(Maritime Antarctica)

(1) Geophysical Centre of Evora, University of Evora, Evora, Portugal, (2) Department of Physics and Geophysical Centre of Evora,

University of Evora, Evora, Portugal, (3) Centre for Geographical Studies, University of Lisbon, Lisbon, Portugal, (4) Department of

Physics, University of Alcalá, Madrid, Spain, (3) Centre for Geographical Studies, University of Lisbon, Lisbon, Portugal

INTRODUCTION

Two boreholes were drilled, with continuos coring to collected as many samples as possible

for laboratory studies, near the Bulgarian Antarctic Base (BAB) of St. Kliment Ohridski, in

the Hurd Peninsula in the Island of Livingston (Maritime Antarctica) under the framework of

the PERMANTAR (Permafrost and Climate Change in the Maritime Antarctic) project. The

PERMANTAR project is one of the Portuguese aid to the core projects ANTPAS (Antarctic

and Sub-Antarctic Permafrost, Soils and Periglacial Environments) and TSP (Permafrost

Observatory Project – Thermal State of Permafrost) of the International Polar Year. Here the

results of the first measurements performed in cores collected in two boreholes drilled on a

CALM site (with coordinates 60º21’44.3’’W 62º38´48.5’’S, figure 1) and PAPAGAL site

(with coordinates 60º21’49.3’’W 62º38’54.2’’S Figure 1) are present. The boreholes distance

from each other coarse 187 metres, (figure 1).

The thermal conductivity and thermal diffusivity are two physical properties of rock

materials that are related to how thermal energy is transmitted through them, and so they also

fundamental to describe and understand energy transfer in soil and, in particular, in

permafrost areas. Thermal conductivity is a measure of the efficiency with which materials

conduct heat energy; thermal diffusivity measures the efficiency with which materials lose or

absorb energy. For isotropic and homogeneous materials thermal conductivity () can be

defined by the quotient between the rate at which heat is conducted through the unit area (q)

and the temperature gradient or the change in the temperature with depth (∆T).

Figure 1: CALM site and PAPAGAL site location. (a) Drilling on Livingston Island The thermal diffusivity (α) depends on the thermal conductivity () according to the

following expression:

where ρ is the density and Cp is the volume heat capacity.

Paulo Amaral amaral.paulomaciel@gmail.com (1), António Correia correia@uevora.pt (2),

Gonçalo Vieira gtvieira@ceg.ul.pt (3), Miguel Ramos miguel.ramos@uah.es (4),

Alexandre Trindade alexandretn@gmail.com (3)

Table 1: Thermal conductivity, thermal diffusivity (dry samples), and heat production values for the cores collected in the

CALM and Papagal sites boreholes, Livingston Island. TCa, TCb, and TCc, and, TDa, TDb, and TDc refer to the

measurement directions of thermal conductivity and thermal diffusivity, respectively, along (a), (b), and (c) directions of

Figure 2.

Figure 2: Directions

of measurement of the

thermal conductivity

and the thermal

diffusivity.

1.25

1.30

1.35

1.40

1.45

1.50

1.55

1.60

1.65

1.70

0.00 1.00 2.00 3.00 4.00 5.00 6.00

Th

erm

al d

iffu

siv

ity

(m

2/s

*

10

-6)

Depth (m)CALM PAPAGAL

2.50

2.70

2.90

3.10

3.30

3.50

3.70

0.00 1.00 2.00 3.00 4.00 5.00 6.00

Th

erm

al c

on

du

ctiv

ity

(W

/m.K

)

Depth (m)CALM PAPAGAL

THERMAL CONDUCTIVITY AND THERMAL

DIFFUSIVITY MESUREMENTS

There are being made measurements on the cores on the laboratory

of the thermal conductivity and thermal diffusivity that allows to

interpreted thermal transfer and heat flux phenomena on soils and

rocks of the area. The measurements of the thermal conductivity

and the thermal diffusivity were made in three orthogonal

directions (a, b, and c), as shown in Figure 2, with cores dry. The

determination of the cores (figure 4) from the two boreholes was

made using a TCS Lippmann & Rauen GbR equipment.

RESULTS AND ANALYSYS:

On the Table 1 are the values of the thermal conductivity, the thermal

diffusivity, and the heat production for cores obtained in the boreholes

drilled in January, 2008, in the CALM site (Figure 1) and the

PAPAGAL site (Figure 1). The variations on thermal conductivity and

thermal difuvivity according to the cores are shown on figure 4 and the

average according to depth are shown on figure 5. Table 1 also shows

the values of the heat production for the two boreholes. A SILENA

gamma-ray spectrometer was used to determine the contents in

uranium, thorium and potassium from bits of the cores from the two

boreholes. For each borehole those values are presented as well as the

heat production values which are 1.30 µW/m3 for the borehole in the

CALM site and 0.70 µW/m3 for the borehole in the PAPAGAL site.

CONCLUSIONS

The highest values of thermal conductivity were measured in the cores from the PAPAGAL site; the CALM

site has the highest thermal diffusivity value and the lowest thermal conductivity value.

The results presented here are preliminary and are far from been completed. There is being made porosity

tests to calculate the thermal conductivity values for the cores with the pores filled with water and ice, which

correspond to the climatic environment of the area where the boreholes were drilled.

REFERENCE:Schön, J. H. (1996). Physical properties of rocks: fundamentals and principals of petrophysics,

Handbook of Geophysical Exploration, Section I, Seismic Exploration, Vol. 18). Oxford, Pergamon.

ACKNOWLEDGEMENTS: The authors thank the Fundação para a Ciência e a Tecnologia for funding the

project PERMANTAR which allowed to collect the cores used in the presentation and process the data. One of

the authors (PMA) acknowledges the grant of Caixa Geral deDepósitos.

Figure 3: Average of thermal diffusivity and thermal condutivity values for the CALM and PAPAGAL sites according to

core depth.

Figure 4: Images of some cores submitted to thermal

conductivity tests and thermal diffusivity tests on TCS Lippman

& Rauen Gbr equipment .