Geochemistry of siltstones of the Early Cretaceous Laiyang Group in Taolin area, Shandong Province, Eastern China: Implications for provenance, source weathering, palaeo‐environment, and tectonic setting

Abstract

The depositional environment and tectonic setting of the newly identified Ri-Qing-Wei Basin are the focus of controversy. In order to solve these questions, the geochemical characteristics of siltstones from Laiyang Group in Taolin area are analysed in detail. The siltstones present similar contents of SiO 2 and Al 2 O 3 compared with upper continental crust (UCC) and post-Archean Australian Shale (PAAS) and are classified as wacke on chemical classification plot of clastic rocks. The trace elements are characterized by the depletion of transition elements (Sc, V, Cr, Ni, and Cu). The chondrite-normalized REE patterns exhibit the enrichment of LREE and depletion of HREE, as well as significant negative Eu anomalies. Relative high Index of Compositional Variability (ICV) values suggest the siltstones are compositionally immature and the sediments of first-cycle. The low Chemical Index of Alteration (CIA) and Plagioclase Index of Alteration (PIA) values of the samples indicate the weak source weathering condition. Moreover, the characteristics of A-CN-K plot suggest K-metasomatism occurred after burial. A series of palaeo-environment indexes imply that the Laiyang Group were deposited in a reducing marine environment with hot and arid climate. Major-and trace-based tectonic setting discriminant diagrams all indicate that the Ri-Qing-Wei Basin was formed in an active continental margin setting; this conclusion is also supported by the analysis of the coeval igneous rocks. Based on the investigations of the subduction of the Palaeo-Pacific plate and the development of Cretaceous basins on the eastern Eurasia, we propose that Ri-Qing-Wei Basin was formed in response to the delamination of the North China Craton and the subduction of Izanagi plate.

Geochemistry and geochronology of Upper Triassic sedimentary rocks from the south of the Dabie Orogen: Implications for the paleoenvironment, provenance and tectonic setting

“…The A–CN–K ternary plot (Figure 8; Al 2 O 3 –(CaO* + Na 2 O)–K 2 O) is a reliable tool for monitoring weathering trends (Kasanzu et al, 2008; Moosavirad et al, 2011; Ogala, 2022; Ramirez‐Montoya et al, 2021; Wang et al, 2012; Zeng et al, 2020; Zhang et al, 2018). As a result of the metasomatism of potassum, the weathering trend tends to be in the direction of illite and muscovite at A–K and close to the A vertex (Fedo et al, 1995).…”

“…is a reliable tool for monitoring weathering trends (Kasanzu et al, 2008;Moosavirad et al, 2011;Ogala, 2022;Ramirez-Montoya et al, 2021;Wang et al, 2012;Zeng et al, 2020;Zhang et al, 2018).…”

Geochemistry, Detrital Zircon U-Pb Geochronology, and Lu-Hf Isotopes of the Metasedimentary Rocks (Xinghongpu Formation, Late Devonian) in the Central South Qinling Orogenic Belt: Implications for Provenance and Tectonics

“…(2) Tectonic setting in the Late Devonian It has been shown that the chemical compositions of the sediments can be related to plate tectonic processes, making geochemistry a powerful tool for recognizing ancient tectonic settings [50,[76][77][78]. The value of K 2 O/Na 2 O of sedimentary rock behaves differently from its SiO 2 content in different tectonic settings.…”

Geochemical Characteristics and Evaluation Criteria of Overmature Source Rock of the Laiyang Formation in Well LK-1, Riqingwei Basin, Eastern China

“…Among them, the cumulative thickness of dark mudstone is 520 m, and the cumulative thickness of dark argillaceous siltstone and siltstone is 450 m. Overall, the Laiyang Formation in well LK-1 is a potential high-quality source-rock development horizon with dark fine-grained deposits [10] (Figure 1d). [24]); (b) geological map of the Riqingwei basin (modified from [25]); (c) geological map of the Lingshan Island, location of well LK-1(modified from [22]); and (d) composite stratigraphic column and sampling locations of the Laiyang Formation in well LK-1(modified from [22]).…”

“…Methods for evaluating organic-matter abundance in source-rock samples include TOC content determination, rock pyrolysis analysis and Chloroform bitumen "A" content [24]); (b) geological map of the Riqingwei basin (modified from [25]); (c) geological map of the Lingshan Island, location of well LK-1(modified from [22]); and (d) composite stratigraphic column and sampling locations of the Laiyang Formation in well LK-1(modified from [22]).…”