>>452
array環境の中にarray環境を入れれば良いだけかと

\left(\begin{array}{cc}
\left(\begin{array}{cc}a11&a12\\a21&a22\end{array}\right) &
\left(\begin{array}{cc}b11&b12\\b21&b22\end{array}\right) \\
\left(\begin{array}{cc}c11&c12\\c21&c22\end{array}\right) &
\left(\begin{array}{cc}d11&d12\\d21&d22\end{array}\right)
\end{array}\right)

こんな感じで