Geochemical Constraints of Sediments on the Provenance, Depositional Environment and Tectonic Setting of the Songliao Prototype Basin

The geochemistry of sediments is primarily controlled by their provenances, and different tectonic settings have distinctive provenance characteristics and sedimentary processes. So, it is possible to discriminate provenances, depositional environments and tectonic settings in the development of a sedimentary basin with the geochemistry of the clastic rocks. The analytical results of the present paper demonstrate that sediments in the Songliao prototype basin are enriched in silica (SiO2=66.48-80.51 %), and their ΣREE are 30-130 dmes of that of chondrite with remarkable Eu anomalies. In discriminating diagrams of Eu/Eu vs eeeeeREE and (La/Yb)N vs ΣREE, most samples locate above the line Eu/ Eu=l, on the right of the line Eu/Eu/ΣREE=1 and under the line La/Yb)N/eeeeeREE=1/8, which indicates that the depositional environment of sediments in the basin was oxidizing. In addition, variations of MgO, TiO2, A12O3, FeO+Fe2O3, Na2O and CaO vs SiO2 reflect a tendency of increasing mineral maturity of sediments

Geochemical Constraints of Sediments on the Provenance, Depositional Environment and Tectonic Setting of the Songliao Prototype Basin

Abstract The geochemistry of sediments is primarily controlled by their provenances, and different tectonic settings have distinctive provenance characteristics and sedimentary processes. So, it is possible to discriminate provenances, depositional environments and tectonic settings in the development of a sedimentary basin with the geochemistry of the clastic rocks. The analytical results of the present paper demonstrate that sediments in the Songliao prototype basin are enriched in silica (SiO₂=66.48–80.51%), and their ΣREE are 30–130 times of that of chondrite with remarkable Eu anomalies. In discriminating diagrams of Eu/Eu* vs ΣREE and (La/Yb)_N vs ΣREE, most samples locate above the line Eu/ Eu*=1, on the right of the line Eu/Eu*/ΣREE=1 and under the line La/Yb)_N/ΣREE=1/8, which indicates that the depositional environment of sediments in the basin was oxidizing. In addition, variations of MgO, TiO₂, Al₂O₃, FeO+Fe₂O₃, Na₂O and CaO vs SiO₂ reflect a tendency of increasing mineral maturity of sediments in the basin. Analyses also show that the protolytes of the sediments in the basin were felsic igneous rocks, and the Songliao prototype basin was in a tectonic setting of an island arc on an active continental margin, with violent sinistral strike‐slip.