Question

what boundary caused the pangea to break apart

Answer 1

Pangaea broke apart because the continental lithosphere was pulled apart by extensional (divergent) tectonics — i.e., rifting that evolved into seafloor spreading at mid‑ocean ridges.

Key points:
- The breakup began in the Late Triassic–Early Jurassic (~200 Ma) when rifts opened within Pangaea and separated it into Laurasia and Gondwana.
- Rifting (a kind of divergent plate boundary) thinned and fractured the crust, forming rift valleys and then oceanic crust as seafloor spreading started (mid‑ocean ridges).
- Mantle processes (hotspot/plume activity, e.g., associated with the Central Atlantic Magmatic Province) helped weaken and uplift the lithosphere and promoted rifting.
- Transform faults and subduction zones elsewhere then reorganized the pieces and drove their later motions (for example, the Atlantic opened progressively between ~200 and 120 Ma).

So the primary boundary type responsible was divergent (extensional/rift) boundaries that later became spreading centers (mid‑ocean ridges).