  We introduce trianguline deformation spaces $X_{\tri} (\overline{\rho})$ for
a $\GSp_{2n}$-valued residual representation $\overline{\rho} \colon
{\mathcal{G}}_K \to \GSp_{2n} (k)$, where $k$ is a finite field of
characteristic $p > 0$ and ${\mathcal{G}}_K$ is the absolute Galois group of a
finite extension $K / {\mathbb{Q}}_p$, and study their properties. We show
Zariski density of the crystalline points on the rigid generic fiber
${\mathfrak{X}}_{\overline{\rho}}$ of the framed deformation space of
$\overline{\rho}$ under some conditions.
