Dating of authigenic minerals in sedimentary rocks: A review

Abstract

Sedimentary rocks host vast geological resources, such as fossil fuels and various types of metallic and nonmetallic mineral deposits, and record the information of long-term environmental, climatic, and biological evolutions. Timing of hydrocarbon accumulation, metal mineralization, and sedimentary diagenesis is important for both resource exploration and geological research. This paper provides a review of dating methods relying on the K-Ar and Rb-Sr isotopic decay systems applied in sedimentary rocks, including K-Ar, Rb-Sr, 40Ar/39Ar dating of authigenic glauconite, illite, and K-feldspar, as well as in situ 40Ar/39Ar dating of zoned K-feldspar overgrowths and in situ Rb-Sr dating of glauconite. Sample preparation and analytical techniques associated with these methods are discussed, including characterization and separation procedures to assess the reliability of produced data. Finally, several applications of these techniques in various sedimentary settings are summarized, such as the diagenetic evolution of Rotliegend sandstones of the Northern Germany Basin and the hydrocarbon accumulation of the Brent Group sandstone reservoir in the North Sea. Also chert, a siliceous sedimentary rock usually containing potassium, has been dated with Rb-Sr and 40Ar/39Ar dating to determine depositional ages and trapped ancient atmospheric argon components.