Context:

Los Tábanos Rhyodacite, located in San Juan del Cesar (La Guajira) within the Sierra Nevada de Santa Marta Massif, exhibits outcrops affected by ongoing chemical weathering processes, primarily oxidation. This alteration results in the formation of iron minerals that provide relevant information on the petrological evolution of the rock.

Objective:

To characterize the iron manifestations, evaluating their petrological significance and mineralogical phases.

Methodology:

Representative samples were analyzed using complementary analytical techniques; stereomicroscopy, scanning electron microscopy (SEM), X-ray diffraction (XRD), wavelength-dispersive X-ray fluorescence (WDXRF), attenuated total reflection infrared spectroscopy (ATR-IR), and Raman spectroscopy. These methods enabled the identification of mineral phases and the assessment of the mineralogical and microstructural complexity of the samples.

Results:

Mineralogical analysis revealed the presence of magnetite, hematite, quartz, and actinolite. The data indicate that iron mineral occurrences develop primarily on recently fractured surfaces, where chemical weathering is active. Overall, the samples exhibit low mineralogical and microstructural complexity.

Conclusions:

Los Tábanos Rhyodacite undergoes active oxidation process associated with the interaction of iron with oxygen and water. This process mainly produces magnetite and hematite, minerals that reflect the chemical conditions of the environment and the degree of alteration of the rock. The low mineralogical complexity observed suggests a relatively simple system of mineral transformation.