Palaeokarstic surfaces in the Upper Cretaceous limestones of central Jamaica

Two prominent pitted surfaces in rhythmic, late Maastrichtian, rudist-bearing limestones in central Jamaica are described. The lower surface is pock-marked with small pits that form a nodular, mamillated surface. The pits are roughly circular to gently elliptical in plan view. They vary in diameter from 5–170 mm and in depth from 5–90 mm, and are orientated perpendicular to bedding. This surface is buried beneath a lignite-rich siltstone bed. The upper surface contains microkarren phenomena represented by small cylindrical potholes up to 40 mm in diameter and 30 mm deep. These surfaces are interpreted as palaeokarstic because the pits are: (1) perpendicular to bedding and not the present land surface; (2) infilled with very poorly sorted siltstone, and (3) overlain by lignitic shales indicating terrestrial influx. The presence of two palaeokarstic surfaces in late Maastrichtian limestones suggests short-period cycles in relative sea level, consistent with glacial-eustatic driving mechanisms.