Calcite is frequently formed during alteration processes in the basaltic, uppermost layer of juvenile oceanic crust. Weathered oceanic basalts are hard to date with conventional radiometric methods. We show in a case study from the North Pamir, Central Asia, that calcite U–Pb age data, supported by geochemistry and petrological microscopy, have potential to date sufficiently old oceanic basalts, if the time span between basalt extrusion and latest calcite precipitation (~ 25 Myr) is considered.