Transformation of the radionuclides composition of river sediments in the area of the exploited Lomonosov diamond deposit (NW Russia)

Abstract Sediment cores were collected in Lake St. Clair in 1985 and in the St. Clair River in 1986 to investigate the horizontal and vertical distribution and association of Hg in the sediments. A layer of recent sediment up to about 35 cm thick was differentiated by the geochemical composition and visual appearance from the underlying glacial-lacustrine deposits. The concentration of Hg in the surficial sediments in Lake St. Clair was lower in 1985 (<0.025 to 1.200 µg/g) than that found in 1974 (<0.20 to 3.00 µg/g). Up to 8.30 µg/g of Hg were found in the sediments collected from the nearshore area at Sarnia, Ontario, in the St. Clair River in 1986. The concentrations of Hg ranged from 5.05 to 16.00 µg/g in different sand-sized fractions (0.063 to 0.350 mm) of the sediment. The concentration of Hg was 17.80 µg/g in the silt-clay size fraction (<0.063 mm). No relationship was found between the concentration of organic matter and Hg, and the concentration of silica and Hg in the St. Clair River sediments. The results indicated a relationship of Hg with particles of different mineralogical composition. Up to 3.72 µg/g Hg was found in the surface sediment in Chenal Ecarte. The greatest concentration of Hg (13.15 µg/g) existed in the 0.350 mm particle size fraction, which consisted mainly of small pieces of decaying wood. A good relationship was found between the concentration of Hg and organic matter in the sediment at this area.

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Modeling of dense well block point bar architecture based on geological vector information: A case study of the third member of Quantou Formation in Songliao Basin

Open Geosciences ◽

10.1515/geo-2020-0222 ◽

2021 ◽

Vol 13 (1) ◽

pp. 39-48

Author(s):

Chao Luo ◽

Ailin Jia ◽

Jianlin Guo ◽

Wei Liu ◽

Nanxin Yin ◽

...

Keyword(s):

River Sediments ◽

Three Dimensional ◽

Songliao Basin ◽

Point Bar ◽

Meandering River ◽

Architecture Model ◽

The Third ◽

Continuous Convergence ◽

Vector Information ◽

Architecture Modeling

Abstract Although stochastic modeling methods can achieve multiple implementations of sedimentary microfacies model in dense well blocks, it is difficult to realize continuous convergence of well spacing. Taking the small high-sinuosity meandering river sediments of the third member of Quantou Formation in Songliao Basin as an example, a deterministic modeling method based on geological vector information was explored in this article. Quantitative geological characteristics of point bar sediments were analyzed by field outcrops, modern sediments, and dense well block anatomy. The lateral extension distance, length, and spacing parameters of the point bar were used to quantitatively characterize the thickness, dip angle, and frequency of the lateral layer. In addition, the three-dimensional architecture modeling of the point bar was carried out in the study. The established three-dimensional architecture model of well X24-1 had continuous convergence near all wells, which conformed to the geological knowledge of small high-sinuosity meandering river, and verified the reliability of this method in the process of geological modeling in dense well blocks.

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