Logan intrusions

Diabase and gabbro sills and dikes; locally porphyritic (~1,108, 1,115 Ma).
State Minnesota
Name Logan intrusions
Geologic age Mesoproterozoic
Lithologic constituents
Major
Igneous > Hypabyssal > Mafic-hypabyssal (Diabase, Dike or sill)locally porphyritic
Igneous > Plutonic > Gabbroic > Gabbro (Dike or sill)locally porphyritic
Comments Reversely polarized intrusions. Part of the Keweenawan Supergroup and Midcontinent Rift Intrusive Supersuite.
References

Jirsa, Mark A., Boerboom, Terrence J., Chandler, Val W., Mossler, John H., Runkel, Anthony C., and Setterholm, Dale R., 2011, S-21 Geologic Map of Minnesota-Bedrock Geology; Minnesota Geological Survey, State Map Series S-21. Scale 1:500,000.

NGMDB product
Counties Cook