Raw and Refined Data – Guaíba Lake Borehole Cores (LG)
Description
This dataset compiles the research data that underpin the study on the evolution of the Jacuí Delta, in Rio Grande do Sul, Brazil, interpreted as a confined bayhead delta developed within Lake Guaíba. The material includes the raw and processed datasets used in the research, consisting of information from SPT borehole cores, granulometric analyses, Total Organic Carbon (TOC) contents, geochemical data obtained by ICP-OES/MS, and mineralogical results from X-ray diffraction (XRD). The data include samples and cores distributed along the channel–Guaíba basin gradient, near the prodeltaic sector, enabling the documentation of the internal architecture of the deltaic system, its hydrodynamic compartmentalization, and its sedimentary connectivity. The dataset was organized to ensure traceability between analytical data, stratigraphic interpretation, and the results presented in the manuscript, supporting reproducibility, validation of interpretations, and future use in sedimentological, stratigraphic, paleoenvironmental, and geomorphological studies of the coastal–lagoonal system of southern Brazil.
Files
Steps to reproduce
To generate this dataset, a reproducible workflow was adopted based on the integration of multiple lines of evidence. The study combined three main methodological approaches: (1) subsurface data from borehole cores obtained by Standard Penetration Test (SPT), (2) sedimentological and granulometric analyses associated with Total Organic Carbon (TOC) determination, and (3) elemental and mineralogical characterization using ICP-OES/ICP-MS and X-ray diffraction (XRD). These results were later integrated through column-profile interpretation and stratigraphic correlation within a sequence stratigraphy framework. The dataset is mainly based on borehole cores provided by FEPAM, the state environmental agency of Rio Grande do Sul, obtained through percussion drilling with SPT. Twelve cores distributed between the Lake Guaíba basin and the prodeltaic sector were examined to represent the channel–Guaíba basin–prodelta gradient, and seven were selected as the most representative for the analytical stages. Because SPT recovers disturbed samples of unconsolidated sediments, the work focused on lithological description, textural characterization, recognition of vertical facies changes, and lateral correlation among the cores. Granulometric analysis followed the protocol of the Center for Coastal and Ocean Geology Studies (CECO/UFRGS). Samples were manually disaggregated with pestle and mortar, pre-sieved through a 1 mm mesh, and analyzed with a HORIBA LA 950 laser instrument to determine grain-size percentages by class. Results were organized into integrated tables and graphs, and textural classes were defined according to the proportions of sand, silt, and clay following Shepard (1954). Samples with higher fine-fraction content were also analyzed for TOC to support the interpretation of depositional conditions and organic matter preservation in lower-energy environments. Elemental geochemistry was carried out by ICP-OES and ICP-MS on six samples from the key core LG124. Mineralogical support was obtained by XRD on six samples from the same core. For XRD, the powder method was applied: samples were finely ground and mounted in random, non-oriented arrangements to obtain representative diffraction peaks for mineral identification. Analyses were performed at the UFRGS X-ray Diffraction Laboratory (LDRX) using a SIEMENS/BRUKER D-5000 diffractometer. The final interpretation integrated borehole descriptions, granulometric data, TOC contents, ICP-OES/ICP-MS results, and XRD analyses into facies standardization, facies associations, column profiles, and kilometer-scale stratigraphic correlations, allowing the recognition of vertical stacking patterns, lateral continuity and discontinuity of units, and the internal organization of the Jacuí deltaic system.
Institutions
- Universidade Federal do Rio Grande do SulRio Grande do Sul, Porto Alegre