Geostatistical modeling of stream sediment anomalies in the Biga Peninsula, NW Türkiye: A threshold-based approach for mineral exploration

2025-08-27T10:56:39+00:00

The Biga Peninsula (NW Türkiye), a key segment of the Alpine–Himalayan metallogenic belt, is characterized by extensive mineralization and geological complexity. This study integrates stream sediment geochemistry and geostatistics to model the spatial distributions of As, Cu, Pb, Zn, and Cd based on 2,369 stream sediment samples. The geochemical results indicate wide concentration ranges for the elements: As (from 3.00 to 839.00 ppm), Cu (from 3.67 to 1680.00 ppm), Pb (from 5.00 to 3989.62 ppm), Zn (from 8.00 to 17762.20 ppm), and Cd (from 0.10 to 210.20 ppm), with standard deviations ranging from 6.43 ppm (Cd) to 488.18 ppm (Zn). Descriptive statistics reveal non-normal distributions, with strong correlations among Zn-Cd (r=0.92), Pb-Zn (r=0.90), and Pb-Cd (r=0.84), while As and Cu appear to be geochemically independent. Cluster analysis confirms a strong geochemical affinity among Cd, Zn, and Pb, whereas As and Cu remain unrelated. Five statistical methods -arithmetic mean, median, interquartile range, percentile-based approach, and cumulative probability- were used to determine elemental threshold values, leading to the classification of anomalies as moderate, high, and very high. Variogram modeling reveals isotropic spatial patterns, enabling the use of ordinary kriging to estimate values at 15,312 grid points. Anomaly maps highlight a distinct Cd anomaly in the southeast, overlapping Zn-Pb-Cd zones, along with independent Cu-As patterns. Comparison with known mineral deposits confirms strong spatial correlations. High As concentrations were associated with the Sahinli, Kocatarla, and Balya deposits, whereas Cu anomalies aligned with the Koru, Kuşçayır, Handeresi, Bağırkaçdere, Tepeoba, Kocatarla, and Arapuçandere deposits. Pb- Zn-Cd anomalies correspond to mineralized zones such as Koru, Handeresi, Bağırkaçdere, and Balya. This study demonstrates a novel application of integrated geochemical and geostatistical modeling, employing a comparative, threshold-based approach to identify mineral exploration targets in the geologically complex Biga Peninsula.

Fluid inclusion and Pb–O isotope constraints on the genesis of the Jurassic Karaburun VMS deposit (Central Pontides, Türkiye)

2025-11-25T10:05:08+00:00

The Jurassic Karaburun deposit in Central Pontides is the largest known VMS deposit in Türkiye, containing ~125 Mt of ore averaging 1.16 wt. % Cu, 0.25 wt. % Zn, and 0.05 wt. % Co. Mineralization occurs within low-grade greenschist rocks of the Çangaldağ Metamorphic Complex, a tectonic unit of the Central Pontides. It is associated with volcaniclastic, detrital, and deep-marine sediments, along with cross-cutting mafic dikes and sills. The mineralization is predominantly stratiform, forming sheet-like to tabular bodies with disseminated, banded, pyritic clastic, semi-massive, and massive sulfide textures.

δ¹⁸O values of quartz in different ore textures range from 11.79‰ to 14.40‰, corresponding to calculated hydrothermal fluid values of 1.22-4.20‰ V-SMOW. Fluid inclusions with two phases (liquid + vapor) in the quartz of mineralized sections show eutectic temperatures of −10.9 to −26.0 °C, final ice-melting from −0.8 to −7.5 °C, and homogenization temperatures of 178-301 °C, with salinities of 1.4-11.1 wt. % NaCl eq. (avg. ~6.5 wt. %). Pressure corrections indicate minimum trapping temperatures of ~223 ± 25 °C. Microthermometric, oxygen isotope data and formational settings of the deposit collectively indicate ore-forming hydrothermal fluids are seawater-dominated H₂O–NaCl fluids slightly and likely modified by magmatic fluids/volatiles. Narrowly constrained, non-radiogenic Pb isotope ratios (²⁰⁸Pb/²⁰⁴Pb= 37.463-37.751; ²⁰⁷Pb/²⁰⁴Pb= 15.424–15.503; ²⁰⁶Pb/²⁰⁴Pb= 18.079–18.431) indicate a mantle-derived source for lead in the massive sulfides and they also conform to the global lead evolution curve while showing temporal consistency with the growth of ore lead.

Periodico di Mineralogia

Geostatistical modeling of stream sediment anomalies in the Biga Peninsula, NW Türkiye: A threshold-based approach for mineral exploration

Fluid inclusion and Pb–O isotope constraints on the genesis of the Jurassic Karaburun VMS deposit (Central Pontides, Türkiye)