Research Article
Statistical Analysis of Oversize, Slimes, and Heavy Mineral Fractions of the Ranobe Mineral Sands Deposit (Atsimo-Andrefana Region, Madagascar)
Ria Raonison*
,
Tsiorisoa Harempahasoavana,
Théodore Razakamanana
Issue:
Volume 15, Issue 5, October 2026
Pages:
216-223
Received:
10 August 2026
Accepted:
22 August 2026
Published:
9 September 2026
Abstract: This study presents an exploratory statistical analysis of oversize (OS), slimes (SL), and heavy mineral (HM) fractions from 598 deep drilling samples collected across the Ranobe mineral sands deposit, located within the Atsimo-Andrefana region of southwestern Madagascar. Robust descriptive statistical methods and exploratory graphical analyses were employed to quantitatively characterize the spatial distributions, central tendencies, and inherent heterogeneities of these mineralized coastal formations. The structural results indicate a clear dominance of the HM fraction, which features a remarkably stable distribution centered around a high median value of 4.80%. This pattern strongly implies the persistent influence of highly efficient regional enrichment processes driven by hydraulic sorting and gravity concentration dynamics in a moderate-energy beach environment. Conversely, the fine-grained SL fraction exhibits a significantly wider dispersion and pronounced sample-to-sample variability (median of 3.33%, standard deviation of 11.64%), reflecting active hydrodynamic fluctuations and episodic inputs of suspended fine particles during deposition. The coarse OS fraction remains virtually negligible across the vast majority of analyzed samples, maintaining a median of 0%. Bivariate correlation assessments reveal a moderate positive coupling between the OS and SL phases (r ≈ 0.48), whereas their respective linear relationships with heavy minerals are remarkably weak or negative r OS-HM ≈ -0.07; r SL-HM ≈ -0.17). These statistical outputs demonstrate that heavy mineral concentration is entirely decoupled from primary grain-size metrics. Consequently, future operational campaigns must evaluate the economic potential of the Ranobe orebody using independent spatial models.
Abstract: This study presents an exploratory statistical analysis of oversize (OS), slimes (SL), and heavy mineral (HM) fractions from 598 deep drilling samples collected across the Ranobe mineral sands deposit, located within the Atsimo-Andrefana region of southwestern Madagascar. Robust descriptive statistical methods and exploratory graphical analyses wer...
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Research Article
GIS-Based Mapping and Geodatabase Development for Expansive Soils: A Case Study of Selected Towns in the Wolaita Zone, Southern Ethiopia
Issue:
Volume 15, Issue 5, October 2026
Pages:
224-233
Received:
27 September 2026
Accepted:
8 October 2026
Published:
23 October 2026
DOI:
10.11648/j.earth.20261505.12
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Abstract: Expansive soils cause costly damage to infrastructure through seasonal moisture-driven swelling and shrinkage, yet in many developing regions the geotechnical data needed to manage this hazard remains fragmented across paper records and individual project reports. This study addresses that gap by evaluating the engineering properties of expansive soils in three rapidly urbanizing towns in the Wolaita Zone of southern Ethiopia, namely Tebela, Wolaita Sodo, and Boditi, and consolidating the results into a spatially referenced ArcGIS geodatabase to support preliminary engineering design. Fourteen test pits were investigated following ASTM and AASHTO standards, combining ten newly collected field samples with four secondary data sources; index and strength properties, including Atterberg limits, free swell index, swelling pressure, and California Bearing Ratio, were determined in the laboratory, and all test-pit locations were captured by GPS and georeferenced onto rectified imagery in UTM Zone 37N. The results classified the soils at Tebela and Wolaita Sodo as highly plastic clays (CH, AASHTO A-7-5) with high fines contents of 91.8 to 95.1%, free swell indices exceeding 100%, and swelling pressures of 145 to 170 kPa, while the Boditi soils were similarly classified as high-plasticity clays (CH, A-7-6) but showed low California Bearing Ratio values of 2.2 to 2.8%, indicating weak subgrade support. These laboratory results, together with the GPS coordinates, were structured in an ArcGIS file geodatabase organized by town and test pit, with fully searchable laboratory attributes. The resulting system converts scattered paper-based geotechnical records into an interactive, query able geospatial tool and offers an adaptable workflow that can be extended to manage expansive soil risk in other regions facing similar infrastructural and data-management challenges.
Abstract: Expansive soils cause costly damage to infrastructure through seasonal moisture-driven swelling and shrinkage, yet in many developing regions the geotechnical data needed to manage this hazard remains fragmented across paper records and individual project reports. This study addresses that gap by evaluating the engineering properties of expansive s...
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