Geochemistry of the Palaeocene‐Eocene Upper Kelalan Formation, NW Borneo: Implications on palaeoweathering, tectonic setting, and provenance

Abstract

The stratigraphic records of Palaeocene-Eocene are studied with interest as they encompass significant high-resolution information on the environmental and climatic signals. Here, we present whole-rockgeochemistry, mineralogy, and petrography of the turbiditic sedimentary rocks of the Upper Kelalan Formation, NW Borneo, and constraints on palaeoweathering, tectonic setting, and provenance. These are finemedium-grained, poor to moderately sorted, angular to sub-rounded litharenites with lesser occurrences of arkose, wacke, and Fe-sandstone. The dominant proportion of monocrystalline and polycrystalline quartz, followed by K-feldspar and plagioclase and minor amounts of lithic fragments, zircon, etc., with nil-appreciable quantities of clay occur in these rocks. Chemical weathering indices (CIA, CIW, and PIA) values and A-CN-K plot show that the source area has undergone a moderate to an intense degree of chemical weathering and also influenced by the recycling effect. The majority of the sediments are derived from the felsic source area (i.e., granites) with some minor input from the metasedimentary/metamorphic terrain. Based on the geochemical ratios and discriminant diagrams, it is determined that the Schwaner Mountains and its metamorphic group of rocks were the principal provenances with some input from West Borneo Group of rocks. Our data suggest the sediments were deposited initially in an active continental margin setting during the Palaeocene that may have shifted to a passive margin setting during the Eocene age.

Geochemistry of Eocene Bawang Member turbidites of the Belaga Formation, Borneo: Implications for provenance, palaeoweathering, and tectonic setting

“…By putting all possible tectonic settings together, the findings of this study give an overview that the Eocene turbidite sediments of Bawang Member were mainly derived from felsic to mix sources and that the analysed samples belong to the active continental margin with slight passive margin involvement. A somewhat similar tectonic setting for the nearby region has also been reported quite recently, which also strengthens the presented results (Ramasamy et al, 2020).…”

“…The comparative results of elemental ratios (Table 4) are showing that the provenance of Bawang Member is more likely to be a felsic to upper continental rather than the mafic-rich source. The previous literature (Galin et al, 2017;Hennig-Breitfeld et al, 2019;Ramasamy et al, 2020;Shen et al, 2020) reported that the main provenance of the Belaga Formation is from the Schwaner Mountains along with some material being derived from West Borneo and the Tin Belt. The felsic source for Bawang Member (Belaga Formation) is in accordance with the previously proposed source (Schwaner Mountains) of the Rajang Group.…”

Geochemistry of meta‐sediments from Neoproterozoic Shimla and Chail Groups of Outer Lesser Himalaya: Implications for provenance, tectonic setting, and paleo‐weathering conditions

“…Recently, based on the geochemical composition of Neogene‐Quaternary sediments, Verma and Armstrong‐Altrin (2016) proposed discriminant‐function‐based multidimensional diagrams for the discrimination of active and passive margin settings. Such isometric log‐ratio transformations of major and major‐trace element concentrations have been successfully used (Nagarajan, Armstrong‐Altrin, Kessler, & Jong, 2017; Ramasamy et al, 2020). The active margin field includes sediments from arc and collision settings while the passive margin field includes sediments from the rift setting.…”

Subduction history of the Proto-South China Sea: Evidence from the Cretaceous - Miocene strata records of Borneo

“…Late Cretaceous -Late Eocene mudstones of the Rajang Group, Kuching Supergroup and the Lubok Antu mélange are characterized by Chondrite-normalized LREE-enriched REE patterns and negative Eu anomalies, and the UCC-normalized trace element patterns show a Sr negative (Fig. 6a, 6b; Ferdous & Farazi, 2016;Ramasamy et al, 2021;Ahmed et al, 2021;Baioumy et al, 2021;Zhao et al, 2021;Zhu et al, 2021). In the Zr-TiO 2 provenance discrimination diagram, samples from the Kayan and Ketungau Groups of the Kuching Supergroup plot in the felsic region, and Lubok Antu Mélange samples and the Lower Rajang Group (Lupar Formation, Layar Member and Lower Kapit Member) are closer to the intermediate region, while samples from the Upper part of the Rajang Group mostly fall into the felsic region (Fig.…”