Sift together flour, baking powder, and salt. Set aside.
In a separate bowl, mix together yogurt, sugar, eggs, vanilla, lemon zest, and canola oil until just combined.
Pour over dry ingredients and mix until just combined; do not overbeat.
Pour into loaf pan and bake for 45 minutes.
Remove and allow to cool slightly. Remove from pan.
While cake is cooling, pour marmalade into pan. Heat until melted, stirring occasionally. Add yogurt to pan and turn off heat. Stir to combine, then pour slowly over the top of the cake, allowing icing to pool around the sides.