petrologie

Petrology is the science concerned with the origin, composition, structure, and history of rocks. It seeks to understand the processes that form and modify rocks, and to relate rock types to the conditions under which they formed. The term comes from Greek petra, stone, and logos, study.

Petrology is commonly divided into igneous, metamorphic, and sedimentary petrology. Igneous petrology studies rocks formed by the crystallization of molten material, including granites, basalt, and obsidian, and considers the chemical composition and textures produced during cooling and differentiation. Metamorphic petrology examines rocks altered by heat, pressure, and chemically active fluids, leading to mineralogical and textural changes without melting. Sedimentary petrology analyzes rocks formed by deposition, compaction, cementation, and diagenesis, including sandstones, shales, and limestones, and their provenance and diagenetic history. Petrography, the microscopic study of rock constituents in thin sections, is a core method across all branches, aided by mineralogical and geochemical analyses.

Methodologically, petrology combines field mapping with laboratory techniques such as mineralogical analysis, X-ray diffraction, electron microscopy, and isotopic dating. Experimental petrology recreates high-temperature and high-pressure conditions to simulate rock-forming processes.

The field informs understanding of Earth's history, crustal evolution, resource distribution, and environmental conditions. It also extends to planetary petrology, the study of rocks from the Moon, Mars, meteorites, and other bodies. Petrology intersects with geochemistry, mineralogy, and structural geology, and supports applications in resource exploration, construction materials, seafloor and groundwater studies, and hazard assessment.