Micromorphology and genesis of Quaternary stromatolitic tufa crust within the exposed Cretaceous Rayda Formation in Al-Jabal Al-Akhdar, Oman

•Laminated tufa is crusting narrow karst groves within the Rayda Formation limestone.•Lamination is formed of stacked couplets of dark micritic and light sparitic laminae.•Lamination has been developed through five successive biogenic and abiogenic stages.•Tufa has been precipitated from freshwater during an Early Holocene cold pluvial period.