Behrends et al.: Distribution Patterns of Heavy Minerals in Siberian Rivers
267
Methods
To study the present sedimentary environment, surface sediments were taken with a giant
boxcorer during RV Polarstern cruises ARK-IV /3 (Thiede, 1988) ARK-VIII/3 (Ftitterer,
1992), ARK-IX/4 (Ftitterer, 1994), and ARK-XUl (Rachor, 1997), during RV Ivan Kireyev
cruise Transdrift I (Kassens, 1994), ESARE (Dethleff et ai., 1993) and RV Prof. Multanowsky
cruise Transdrift II (Kassens et ai., 1995), RV "Prof. Logachev" and RV "Akademik Golitzin".
In addition, river sediments were collected during the expeditions Lena 94 (Rachold et ai.,
1995), LenalYana 95 (Rachold et ai., 1997) and Khatanga 96 (Rachold et ai., in prep.) with a
heavy pale (Rachold et ai., 1997) (Figure 2).
The heavy minerals of the subfraction 63 - 125Jlm were investigated. The grains were
separated using sodium metatungstate (Na6[H2 W \2040]) with a density of 2.83g/cm3. After
20min centrifugation, the heavy fraction was frozen in liquid nitrogen (Fessenden, 1959; Scull,
1960). The light minerals were decanted, and the heavy minerals were rinsed on filters and
dried. The heavy fraction was mounted with Meltmount (n=I,68) (Mange and Maurer, 1991),
optically identified, and counted using a polarisation microscope. On average about 220 grains
per sample were counted on the strewslides (Table 1). The average content of heavy minerals in
the analysed sand fraction is 6% .
...
Figure 2: Location map of the river samples. Station numbers are indicated.
All heavy minerals including dolomite (detrital carbonate) and opaques are counted and
calculated as 100 grain-%. All informations given in % are grain-%. The group of opaque
minerals is undifferentiated.
Concerning calcite the specific weight is between 2.7 and 2.94 g/cm3, which can be lower
than the density solution of sodium metatungstate. Dolomite, magnesite and siderite (chalybite),
however, have densities of 2.86-2.93, 2.96 and 3.78-3.96 g/cm3, respectively (Boenigk,
1983). Thus, they are interpreted as heavy minerals (Boenigk, 1983; Mange and Maurer,
267
Methods
To study the present sedimentary environment, surface sediments were taken with a giant
boxcorer during RV Polarstern cruises ARK-IV /3 (Thiede, 1988) ARK-VIII/3 (Ftitterer,
1992), ARK-IX/4 (Ftitterer, 1994), and ARK-XUl (Rachor, 1997), during RV Ivan Kireyev
cruise Transdrift I (Kassens, 1994), ESARE (Dethleff et ai., 1993) and RV Prof. Multanowsky
cruise Transdrift II (Kassens et ai., 1995), RV "Prof. Logachev" and RV "Akademik Golitzin".
In addition, river sediments were collected during the expeditions Lena 94 (Rachold et ai.,
1995), LenalYana 95 (Rachold et ai., 1997) and Khatanga 96 (Rachold et ai., in prep.) with a
heavy pale (Rachold et ai., 1997) (Figure 2).
The heavy minerals of the subfraction 63 - 125Jlm were investigated. The grains were
separated using sodium metatungstate (Na6[H2 W \2040]) with a density of 2.83g/cm3. After
20min centrifugation, the heavy fraction was frozen in liquid nitrogen (Fessenden, 1959; Scull,
1960). The light minerals were decanted, and the heavy minerals were rinsed on filters and
dried. The heavy fraction was mounted with Meltmount (n=I,68) (Mange and Maurer, 1991),
optically identified, and counted using a polarisation microscope. On average about 220 grains
per sample were counted on the strewslides (Table 1). The average content of heavy minerals in
the analysed sand fraction is 6% .
...
Figure 2: Location map of the river samples. Station numbers are indicated.
All heavy minerals including dolomite (detrital carbonate) and opaques are counted and
calculated as 100 grain-%. All informations given in % are grain-%. The group of opaque
minerals is undifferentiated.
Concerning calcite the specific weight is between 2.7 and 2.94 g/cm3, which can be lower
than the density solution of sodium metatungstate. Dolomite, magnesite and siderite (chalybite),
however, have densities of 2.86-2.93, 2.96 and 3.78-3.96 g/cm3, respectively (Boenigk,
1983). Thus, they are interpreted as heavy minerals (Boenigk, 1983; Mange and Maurer,