Columbia Hills - An exhumed layered igneous intrusion on Mars?

► The rocks of the Columbia Hills on Mars exhibit a large range in Fe content. ► Observed variation does not reflect differential weathering. ► Observed variation of Mg with Fe is unlike that of basaltic volcanic suites. ► Compositional variation is like cumulate rocks of layered igneous intrusions. ► Columbia Hills represent a layered intrusion, not a pyroclastic volcanic sequence.