plotArealElement[r_, phi_, dr_, dphi_] := Module[
{g1, g2, x, y, u, v, plr},
g1 = ParametricPlot[s {Cos[phi], Sin[phi]}, {s, r, r + dr}, {psi, phi, phi + dphi}];
u = r {Cos[phi], Sin[phi]};
v = r {Cos[phi + dphi], Sin[phi + dphi]};
x = v - u;
v = (r + dr) {Cos[phi], Sin[phi]};
y = v - u;
plr = Options[g1, PlotRange];
g2 = ParametricPlot[s x + t y, {s, 0, 1}, {t, 0, 1}, plr];
Show[g1, g2]
]