Geochemical Characteristics and Constraints on Provenance, Tectonic Setting, and Paleoweathering of Middle Jurassic Zhiluo Formation Sandstones in the Northwest Ordos Basin, North-Central China

Abstract

To further explore the uranium-bearing prospects of the Zhiluo Formation, the petrography, major elements, trace elements and rare earth elements of Zhiluo sandstone samples collected from four boreholes were analyzed in this research to determine the provenance, tectonic setting and paleoweathering of the formation. The results of the analysis reveal that the Zhiluo Formation sandstone comprises primarily feldspar sandstone, with quartz, feldspar, and mica as the main mineral components. The rare earth elements are mainly characterized by enrichment in light rare earth elements and loss of heavy rare earth elements. The ratio of light to heavy rare earth elements (LREEs/HREEs) is 5.55–7.79, with an average of 6.33. The value of (La/Yb)CN is 12.96–22.33, with an average value of 17.41, indicating obvious fractionation of LREEs and HREEs. The chemical index of alteration (CIA) value of this sandstone is 56.30–63.04, with an average of 59.75, which indicates that the parent rock experienced weak chemical weathering in a dry climate. The discrimination diagrams of the source area and parent rock show that the source area of the Zhiluo sandstones had a mixed intermediate-felsic composition, and that the main parent rocks were andesite and granite. The tectonic setting discrimination diagram indicates that the tectonic setting of the source area was the passive margin. Thus, the provenance of the sandstone of the Zhiluo Formation is proposed to be the volcanic-sedimentary rock series developed on the northern margin of the Ordos Basin.

Chemostratigraphic Approach to the Study of Resources’ Deposit in the Upper Silesian Coal Basin (Poland)

“…The origin of the quartz is especially important when analyzing the main determinants of the quality of hydrocarbon reservoirs [19]. Several geochemical criteria have been reported for determining the origin of silicon in sedimentary rocks [10,19,46,49].…”

“…In this study, the relationships between TiO 2 and SiO 2 were analyzed to determine the quartz origin. A strong positive correlation between TiO 2 and SiO 2 suggests that terrigenous quartz is a primary source of silica, while a clear negative relationship indicates a high proportion of biogenic silica [10,19,46,49].…”

“…Trace element composition can potentially provide information regarding the provenance of terrigenous sediments and source-area rock compositions [26,46,[49][50][51][52][53][54][55][56].…”

“…The ratios of Al 2 O 3 /TiO 2 and TiO 2 /Zr as well as the abundance of trace elements, such as Zr, La, Sc, Th, and their elemental ratios (Th/Sc and La/Th), are commonly used in provenance studies (e.g., [18,26,46,[49][50][51][52][53][54][55][56][57][58][59]).…”

Mineralogical and elemental geochemical characteristics of Taodonggou Group in Taibei Sag , Turpan-Hami Basin: Implication for Source sink system and evolution history of lake basin

“…Sedimentary rocks of different tectonic settings have prominent differences in element composition and content, so the geochemical characteristics of sedimentary rocks can be used to reflect the tectonic setting of sedimentary basins (Kroonenberg, 1992). (Bhatia and Crook, 1986;Cai et al, 2022). Based on the La-Th-Sc ternary diagram (Fig.…”