MGS Luncheon

MGS Luncheon Meeting

Tuesday, December 8th

11:45 am – Billings Petroleum Club

Please join us for lunch ($14) and the talk (no charge)

RSVP – montanageologicalsociety@gmail.com

*An email reminder will be sent 3 days prior to the talk

Gary Hughes

Geologist Generalisimo Jefe Mayor

SM Energy Company

The Crazy Mountains Basin: Geology at its Best

Central Montana

The Crazy Mountains basin and surrounding areas offer something for every geologist. Any hard rock geo will lose himself in the 2+ billion years old Precambrian metamorphics along the Beartooth Front; particularly within the Archean Stillwater complex where multiple metal zones form a unique and very rare deposit. The sedimentologist and stratigrapher can enjoy any number of relationships in the sediment package, from the Paleozoic section up through the early Tertiary strata. Paleozoic rocks are a bit thinner compared to equivalent rocks to the southeast in the Bighorn Basin. Specifically, the Permo-Penn strata are continually truncated northward to a feather edge. In addition, the upper Cretaceous through early Tertiary sediments are more than 15,000 feet thick and record the un-roofing of uplifts to the west that was accompanied by volcanic activity in the Elkhorn Mountains.

The Crazy Mountains basin is a haven for any structural geologist. The western side of the basin lies in a complex structural area that was impacted by both Cordilleran (Sevier) and Laramide structural styles. Along the northern and southern margins of the basin, one can observe the interplay of Laramide “thick skinned” uplifts and left-lateral strike-slip lineaments creating world class structural interpretation challenges.

Of all the geological professions, petroleum geologists have been the most disappointed in the Crazy Mountains basin. Many “sheep herder” anticlines along the basin margins are devoid of production. Other closures produce dry gas and smaller amounts of oil from lower and upper Cretaceous sandstones. Recent attempts to define basin-centered shale gas plays have perpetuated the disappointment. As a glimmer of hope, an under-explored structural zone that resides in immediately east of the deep basin may offer potential for combination traps formed within the Cretaceous Dakota, Frontier, and Eagle sandstones.

About Gary Hughes:

Gary Hughes received his B.A. degree in 1976 from Augustana College in Rock Island, IL and his MS degree in 1980 from Montana State University, Bozeman, MT. He worked at Texaco, Inc. in Denver, CO for 14 years, working most of the Wyoming and Montana basins. He moved to Billings, Montana in 1994 to work for NARCo, a subsidiary of Montana Power. There he worked the Green River and Anadarko basin. In 2000 and for the next 10 years, Gary started Hughes Exploration, Inc. providing geological consulting services across various Rocky Mountain basins and developing and selling prospects. From 2010 to the present, Gary works in a full time position at SM Energy.