Rare earths in sediments

Abstract

The relative elemental abundances of the rare-earth elements (REE) in a composite of 40 North American shales and in the average for 38 individual sediment samples are found to be identical with each other and with the average determined for sediments of the Russian Platform, to within an experimental uncertainty of ñ10% (standard deviation). The average RE distributions for 9 carbonates, 7 sandstones, 5 graywackes, and 8 ocean sediments are identical with the North American shale distribution to within a standard deviation of _15%, and the average for 9 shales lacks only one element of being so. Only 14 of the 38 individual sediment distributions are identical with the North American shale composite to within ñ15%, but fewer than 3% of the distributions differ in any part by a factor of 2 and fewer than 15% of them differ by a factor of 1.5. The spread in absolute RE content for sediments of a given type ranges from a factor of less than 3 for the ocean sediments to more than 30 for the sandstones. The average absolute RE contents increase in the order limestone, sandstone, graywacke, ocean sediment., shale. The absolute RE contents of the shale composites vary from somewhat more than 75 ppm to 335 ppm. The average total RE content of sediments is probably between 150 and 300 ppm. Preliminary results for separated minerals indicate that the bulk of the REE in the St. Peter sandstone is in the quartz, and in the Byron formation limestone it is in the carbonate. Experiments on adsorption of the REE on calcite are described.

Rare earth element abundances in some seawaters and related river waters from the Osaka Bay area, Japan: Significance of anthropogenic Gd

“…The silicic rock data of Terakado and Masuda (1988) are suitable for the normalization, because these rocks can be considered as representatives of crustal rocks in the area around the Seto Inland Sea (cf., Terakado and Fujitani, 1995). Moreover, the average values of these silicic rocks are similar to those of shales such as PAAS (Post-Archean average Australian shale) (Nance and Taylor, 1976) or NASC (North American shales composite) (Haskin et al, 1966). Furthermore, if a systematic error may occur in our measurements, the bias can be cancelled, because the same analytical technique was adopted for both measurements for those normalizing values and the present data.…”

Search for chemical effect on partitioning of rare-earth elements in the crystallization process of basaltic systems at 20kb, with some applications.

“…As pointed out before (MASUDA and JIBIKI, 1973), the continental material as represented by the North American shale (HASKIN et al, 1966) is the liquid-type material developed by the domi nant control of this kind of p.c. function with a shoulder point at Tb.…”

“…The chondrite-normalized REE patterns (Masuda-Coryell diagrams) of the composite North American shale (HASKIN et al, 1966) and Russian Platform material (BALASHOV et al, 1964) reflect well the bulk p.c. function as designated terrace-shaped.…”

REE Characteristics and REE Mixing Modeling of the Proterozoic Quartzites and Sandstones

“…It may be due to the reason that REEs normally reside in fine fraction and it has been inferred that trivalent REEs are readily accommodated in most of the clay-mica minerals (phyllosilicates) enriched with alumina and ferric iron [22] [23]. Thus, the sandstones with higher quartz and lower mica content have lower REE content, while the quartzites with lower quartz and higher mica content have higher content of REE than the sandstones [5]. Good positive correlation of LREE and HREE with Zr, Th and Y of the sandstones indicate allanite, monazite and zircon control on REE (Figure 3).…”

“…Rare earth elements (REEs) have very similar geochemical properties and are not easily fractionated during sedimentary processes and will not be affected to any great extent during a silicification episode [1]. The REEs are considered to be essentially uniform in abundances in fine grained clastic sedimentary rocks and are not significantly affected by weathering, diagenesis and most forms of metamorphism [5] [6] [7]. The REEs are, therefore, very important in understanding crustal evolution.…”