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
DOI:
10.11648/j.earth.20261505.11
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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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