Origin of the vanadium-uranium geochemical anomalies in the limestones of the Puyango Formation, La Sota (Ecuador): preliminary results

Vanadium (V) and uranium (U) are critical elements for the energy and technology industry. They are characterized by low abundance in the earth crust ' s rocks, but can be concentrated and give rise to sedimentary mineral deposits as a result of redox processes during sedimentation and diagenesis. The anomalies of V-U in La Sota, Ecuador, are found in black limestones and black calcareous shales of Cretaceous age. Here we present the results of a geochemical study and a multivariate geostatistical analysis, which enables us to infer four different associations: 1) disseminated organic matter in the limestones that hold V and Zn, probably in the form of organometallic complexes; 2) phosphatic minerals and concentrations of U, HREE and Ni, which may be incorporated as trace elements in the phosphates, compatible with sedimentation in an anoxic environment; 3) Ca in carbonates from a marine environment; and, 4) litophile elements associated with detritic minerals, such as quartz, plagioclase, feldspar, micas, clays and oxyhydroxides of Fe-Mn-Ti, produced by weathering and erosion. Our findings suggest that V is associated mainly with the organic matter of marine origin in the bituminous limestones, while U is associated with P, thereby indicating the formation of uraniferous phosphates during sedimentation.

Automated summary

Vanadium and uranium are crucial elements in the energy and technology industry, and their formation in sedimentary deposits is influenced by redox processes during sedimentation and diagenesis. A geochemical study in La Sota, Ecuador revealed four different associations: organic matter holding V and Zn, phosphatic minerals and concentrations of U, HREE and Ni, Ca in carbonates from a marine environment, and litophile elements associated with detritic minerals. The findings suggest that V is mainly associated with organic matter, while U is associated with P, indicating the formation of uraniferous phosphates during sedimentation.