Abstract Leucogranites provide timing estimates for deformation, particularly extension, in many orogens. On this basis, the time of extension in the East Greenland Caledonides has been estimated at 420–430 Ma. U‐Pb SHRIMP (sensitive, high‐resolution ion‐microprobe) analysis of zircon and monazite from selected leucogranites was undertaken to establish the age of the Payer Land detachment zone, an extensional structure that places low‐grade metasedimentary rocks on granulite facies gneisses that record high‐pressure (1.4–1.6 GPa) metamorphism at ca. 405 Ma. Deformed equigranular granites associated with upper plate lithologies give ages of \documentclass{aastex} \usepackage{amsbsy} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{bm} \usepackage{mathrsfs} \usepackage{pifont} \usepackage{stmaryrd} \usepackage{textcomp} \usepackage{portland,xspace} \usepackage{amsmath,amsxtra} \usepackage[OT2,OT1]{fontenc} \newcommand\cyr{ \renewcommand\rmdefault{wncyr} \renewcommand\sfdefault{wncyss} \renewcommand\en...