Page 197 - Geochemical Remote Sensing of The Sub-Surface

174 V.T. Jones, M.D. Matthews and D.M. Richers

'-- ?.5cm L,

LICONE RUBBER SEAL
5cm OUTSIDE DIA.
5cm INSIDE DIA.

6. f INJECTION PORT

/-- THREADED P I PE I crn D ~ A.
/ ~ SEPTUM CAP FROM VARI AN
/ J S I L I CONE RUBBER
/ ~ /SEPTUM, ,crn DIA.
I~ r "i'-i~,NJECT,ON PO~T
llllilllllilllll i, - -
2cm ~ -' '-- -

Fig. 5-25. Stainless steel disaggregation mill used in headspace analysis

the Western Overthrust Belt, the results obtained by this technique are in very good
agreement with data from auger holes.
The device used in this technique is a small stainless steel ball-mill containing two
stainless steel or ceramic balls which crush and disaggregate the sample when the ball-
mill is shaken (Fig. 5-25). This approach concentrates the loosely-bound adsorbed gases
into the headspace of the ball-mill. Because of the equilibrium problem mentioned above
under headspace techniques, this sampler was adapted by Whelan (1979) and Whelan et
al. (1980) to ensure that lithified sediments and cuttings are completely broken up during
analysis.
Basically, the technique is as follows. A small (but constant) volume of sediment,
soil or cuttings is placed into the mixer cell along with two ceramic or stainless steel
ball-bearings, and water is added to bring the remaining headspace to 10 cc. The mill is
sealed and placed in a SPEX/Mixer-Mill and agitated for about five minutes. The cell is
then immersed into a hot-water bath at 90~ for three minutes. A 1 ml aliquot of gas-free
water is injected into the cell through a septum-sealed side arm on the cell, and then a 1