Corank spectral sequence for locally symmetric varieties

We construct a new type of spectral sequences for the mixed Hodge structures on the cohomology of locally symmetric varieties. These spectral sequences converge to the edge components in the Hodge triangles, and the E1-terms are expressed by group cohomology associated to the cusps. They already degenerate at E1 in a certain range, which gives a simple expression of some Hodge components. An identity of holomorphic Euler numbers is obtained as a consequence.