Evidence for a concealed Midcontinent Rift-related northeast Iowa intrusive complex

•Large amplitude aeromagnetic and gravity anomalies reflect a largely mafic-ultramafic intrusive complex concealed under Paleozoic cover, the northeast Iowa intrusive complex (NEIIC).•A new apatite U-Pb date of ~1170 Ma indicates the age of a nearby dike swarm.•Cross-cutting relations imaged in geophysical data indicate that the intrusive complex cuts the dike swarm, meaning the maximum age of the NEIIC is ~1170 Ma.•The NEIIC is a major intrusive component of the Midcontinent Rift System, and was likely emplaced during early stages of rifting.•The Belle Plaine fault zone and Fayette structural zone are possible lithospheric-scale structural discontinuities that facilitated NEIIC emplacement.