After their deposition, the sediments are subjected to a series of diagenetic processes that can be more or less pervasive depending on the type of the sediment. The diagenetic processes lead to dissolution, precipitation and recrystallization. In some sediments they induce important changes in the mineralogical composition, but they rarely reach a total, pervasive substitution of the association of the depositional minerals; on the contrary, in the carbonate sediments, there may cause pervasive changes consisting in a complete or almost complete change in the depositional mineralogy.
Aim of the lessons is the description of the diagenetic processes that involve various types of sediment in different environments and in the presence of different fluids, and an introduction to some analytical techniques aimed to recognize these processes.
Course contents summary
Diagenesis of siliciclastic rocks (sandstone and shale)
Diagenetic reactions in the eogenetic realm. Diagenetic reactions in the mesogenetic environment (burial diagenesis). Compaction, carbonate cementation, silica cementation. Dissolution and porosity. Replacement. Autigenesis of clay minerals and zeolites. Diagenetic reactions in telogenetic zone
Diagenesis of carbonatic rocks
Diagenesis on the seafloor: deterioration processes, cementation and dissolution, types of marine cements, recrystallization and neomorphism.
Diagenesis in meteoric environment: geochemical considerations, diagenesis in the vadose zone and in the phreatic zone, diagenesis in telogenetic meteoric environment.
Diagenesis in deep burial environment: physical compaction, chemical compaction (pressure solution), cementation. Stratigraphy of cements, geochemistry of deep burial cements, neomorphism, dissolution, replacement.
Analytical techniques: polarized light optical microscopy, fluid inclusions, cathodoluminescence, scanning electron microscopy, isotopic geochemistry
Boggs S. Jr. (2009) Petrology of sedimentary rocks. Cambridge University Press, Cambridge
Scholle P.A., Ulmer-Scholle D.S. (2003) A color guide to the petrography of carbonate rocks: grains, textures, Porosity, diagenesis. AAPG Memoir 77
Boggs S. Jr., Krinsley D. (2006) Application of cathodoluminescence imaging to the study of sedimentary rocks. Cambridge University Press, Cambridge
Barker C.E., Kopp O.C. (1991) Luminescence microscopy and spectroscopy: qualitative and quantitative applications. SEPM (Society of Sedimentary Geology) Short Course No. 25
Goldstein R.H., Reynolds T.J. (1994) Systematics of fluid inclusions in diagenetic minerals. SEPM Short Course 31
lectures on basic theoretical topics and exercises with applications of the analytical methods to identify the diagenetic process
Assessment methods and criteria
Oral exam with verification of the theoretical knowledge learned, their application to real cases and verification of the logical-deductive skills