Update: Geochemical data from granite and basalt weathering profiles in Kuantan, Malaysia
Description
This dataset provides comprehensive whole-rock geochemical data—including major oxides, trace elements, and Rare Earth Elements (REE)—derived from synthetic weathering profiles developed over basalt and granite bedrock in Kuantan, Peninsular Malaysia. The data was collected to evaluate elemental mobility, distinct saprolitization patterns, and REE fractionation during intense tropical pedogenesis. Sampling and Analytical Methodology: Samples were collected from four genetic horizons (A: topsoil, B: subsoil/oxic, C: saprolite, and R: fresh bedrock) across granite (KG, KPG series) and basalt (KB, DAM, S-series) profiles. Geochemical analyses were conducted via a combined XRF (major elements) and ICP-MS (trace elements) workflow following lithium metaborate-tetraborate fusion, ensuring the quantitative recovery of refractory accessory phases. Loss on ignition (LOI) was determined at 1000°C. Analytical reliability is validated by high recovery rates (97.7–101.5%) against certified reference material (CRM SO-18) and high precision (RPD < 5%) from blind-field duplicates. Calculations and Derived Data: To facilitate the quantitative characterization of weathering intensity and mineral alteration pathways, the dataset includes calculations for several established weathering indices: Chemical Index of Alteration (CIA) Chemical Index of Weathering (CIW) Plagioclase Index of Alteration (PIA) Weathering Index of Parker (WIP) Calculations for CIA, CIW, and PIA integrate necessary corrections for silicate-bound CaO (CaO*) following the McLennan (1993) method to exclude Ca from secondary carbonates and apatite. Additionally, the dataset features Si/Al molar ratios to track desilication, alongside chondrite-normalized REE values (Sun and McDonough, 1989), enabling the evaluation of specific Eu (Eu/Eu*) and Ce (Ce/Ce*) anomalies linked to plagioclase fractionation and redox-sensitive scavenging by Fe-Mn oxyhydroxides. Utility: This dataset supports research into lithological controls on soil formation, geochemical mass transfer, clay mineral formation, and the metallogenic potential of supergene or ion-adsorption type (IAT) REE deposits in tropical regoliths.
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Steps to reproduce
1. Field Sampling and Preparation Samples were collected from synthetic weathering profiles across granite (KG and KPG series) and basalt (KB, DAM, and S-series) bedrock in Kuantan, Peninsular Malaysia. Profiles were divided into four genetic horizons: A (topsoil), B (subsoil/oxic), C (saprolite), and R (fresh bedrock). Bulk samples (2–3 kg) were collected from the center of each horizon, dried, and sieved to <2 mm to isolate the fine-earth fraction for geochemical analysis. 2. Geochemical Analysis (XRF and ICP-MS) Whole-rock major oxide and trace element analyses were conducted at Acme Analytical Laboratories (now Bureau Veritas), Vancouver, Canada. To ensure the complete dissolution of refractory accessory phases (e.g., zircon, monazite), samples underwent lithium metaborate-tetraborate fusion (1:5 sample-to-flux ratio). Major element compositions were determined by X-Ray Fluorescence (XRF) spectrometry on fused glass beads. Trace element and Rare Earth Element (REE) concentrations were determined by Inductively Coupled Plasma Mass Spectrometry (ICP-MS) following the lithium borate fusion. Loss on ignition (LOI) was determined by heating samples at 1000°C for 2 hours. 3. Quality Assurance and Quality Control (QA/QC) Analytical accuracy was verified using the Certified Reference Material (CRM) SO-18, yielding recovery rates of 98.6–99.3% for major oxides and 97.7–101.5% for REE. Analytical precision was monitored using blind-field duplicates, with Relative Percent Difference (RPD) consistently remaining below 5%. Procedural blanks were used to monitor and correct for flux contamination. 4. Data Processing and Weathering Index Calculations Raw oxide weight percentages were converted to molar proportions for the calculation of weathering indices. Silicate-bound CaO (CaO*) was calculated following the McLennan (1993) method to exclude calcium associated with secondary carbonates and apatite. Using these corrected values, four primary weathering indices were calculated: Chemical Index of Alteration (CIA) Chemical Index of Weathering (CIW) Plagioclase Index of Alteration (PIA) Weathering Index of Parker (WIP) Additionally, the Si/Al molar ratio was calculated to quantify progressive desilication. 5. REE Normalization and Anomaly Calculations Raw REE concentrations were normalized against standard chondrite values (Sun and McDonough, 1989). Using the chondrite-normalized values (denoted by subscript N), Cerium (Ce/Ce*) and Europium (Eu/Eu*) anomalies were calculated via the geometric interpolation formulas (Bau and Dulski, 1996) to evaluate redox conditions and plagioclase fractionation, respectively.
Institutions
- University of MalayaKuala Lumpur, Kuala Lumpur