Malnormal subgroups of lattices and the Pukanszky invariant in group factors

Let $G$ be a connected semisimple real algebraic group. Assume that $G(\bb R)$hasnocompactfactorsandlet$\Gamma$ be a torsion-free uniform lattice subgroup of $G(\text{bb}R)$. Then $\mathrm{\Gamma }$ contains a malnormal abelian subgroup $A$. This implies that the $\text{tto}$ factor $\text{vn}(\mathrm{\Gamma })$ contains a masa $\text{fk}A$ with Puk'anszky invariant $\{\mathrm{\infty }\}$.