Abstract
This study reports for the first time the geologic occurrence of natural zeolite A and associated minerals in mudstones from the Cretaceous Paja Formation in the urban area of the municipality of Vélez (Santander), Colombia. These rocks are mainly composed of quartz, muscovite, pyrophyllite, kaolinite and chlorite group minerals, framboidal and cubic pyrite, as well as marcasite, with minor feldspar, sulphates, and phosphates. Total organic carbon (TOC), total sulfur (TS), and millimeter fragments of algae are high, whereas few centimeters and not biodiverse small ammonite fossils, and other allochemical components are subordinated. Na–A zeolite and associated mineral phases as sodalite occur just beside the interparticle micropores (honeycomb from framboidal, cube molds, and amorphous cavities). It is facilitated by petrophysical properties alterations, due to processes of high diagenesis, temperatures up to 80–100 °C, with weathering contributions, which increase the porosity and permeability, as well as the transmissivity (fluid flow), allowing the geochemistry remobilization and/or recrystallization of pre-existing silica, muscovite, kaolinite minerals group, salts, carbonates, oxides and peroxides. X-ray diffraction analyses reveal the mineral composition of the mudstones and scanning electron micrographs show the typical cubic morphology of Na–A zeolite of approximately 0.45 mμ in particle size. Our data show that the sequence of the transformation of phases is: Poorly crystalline aluminosilicate → sodalite → Na–A zeolite. A literature review shows that this is an unusual example of the occurrence of natural zeolites in sedimentary marine rocks recognized around the world.
Highlights
The Swedish mineralogist Axel Fredrick Cronstedt discovered in 1756 the stilbite in allusion to their visibly lost water when heated and named the group of zeolites
Berlinite, chamosite, nacrite, dickite, illite, gibbsite, halloysite, kaolinite, phlogopite, vermiculite, phengite and zeolite as products of weathering, the last of them described in detail in this study
We evaluate the geological characteristics of mudstone and regolith systems, taking in conevaluate the geological characteristics of mudstone and regolith systems, taking in consideration their mineralogy and the environmental conditions, which can be strongly affected by several factors, revealing a complex history of chemical reactions in the origin of zeolitic materials
Summary
The Swedish mineralogist Axel Fredrick Cronstedt discovered in 1756 the stilbite in allusion to their visibly lost water when heated and named the group of zeolites (from theGreek words “zeo” meaning “to boil” and “lithos” meaning “stone”). Most natural zeolites form during diagenetic processes in sedimentary rocks [7,8,9]. Zeolites occurring in volcanic lava flow cavities are formed either during lava pile burial metamorphism [10,11,12], continental basalts' hydrothermal alteration [11,13] or diagenesis in areas of high heat flow caused by active geothermal systems [12,14,15]. As products of hydrothermal crystallization, are generally known from active volcanic rock-associated geothermal systems. Zeolites have been extensively used in various technological applications, which include oil refining processes such as catalytic cracking [32,33], as molecular sieves for separating and sorting molecules [34], as adsorbents for water, soil, and air purification [27,35,36,37,38,39] for removing radioactive contaminants [40], for harvesting waste heat and solar heat energy [41], as detergents [42], as antibacterial [43], as drug delivery for oral and topical administration [44,45]
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