Annihilation by Jeff VanderMeer

Area X has been cut off from the rest of the continent for decades. Nature has reclaimed the last vestiges of human civilization. The twelfth expedition arrives expecting the unexpected, and Area X delivers. They discover a massive topographic anomaly and life-forms that surpass understanding. But it's the surprises that came across the border with them, and the secrets the expedition members are keeping from one another that change everything.