Presentation Title

Investigating the Paleo-Geography of the Brule Formation at Slim Buttes, SD

Presenter Information

Ryan BrownFollow

Advisor Information

Harmon Maher

Location

Dr. C.C. and Mabel L. Criss Library

Presentation Type

Poster

Start Date

2-3-2018 2:15 PM

End Date

2-3-2018 3:30 PM

Abstract

In the southern portion of Slim Buttes, SD, badland exposures contain a large scale, laterally extensive paleo-channel complex in the Oligocene and early Miocene rocks of the Brule Formation. The regional gradient for this locality is assumed to be northeast (Seeland, 1985). A combination of paleocurrent data and interpretations of the internal fill in the southern portion of SB suggests a local current sense trending northwest-southeast and a possible direction trending southeast. Significant normal faulting affects the northern part of Slim Buttes and limited pale-current data from this locality suggests that the current direction is sub-parallel to faulting, inconsistent with the assumed regional paleo-slope (northeast). A broad view of modern erosional patterns reveals a lineament with ridges and valleys also trending northwest-southeast, introducing the possibility that modern erosive patterns may be a rough analogue for paleo-erosion. A suite of paleo-current data was analyzed, in addition to field observations to provide a well understood locality to constrain future work for those interested in the paleogeography of the northern Great Plains.

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COinS
 
Mar 2nd, 2:15 PM Mar 2nd, 3:30 PM

Investigating the Paleo-Geography of the Brule Formation at Slim Buttes, SD

Dr. C.C. and Mabel L. Criss Library

In the southern portion of Slim Buttes, SD, badland exposures contain a large scale, laterally extensive paleo-channel complex in the Oligocene and early Miocene rocks of the Brule Formation. The regional gradient for this locality is assumed to be northeast (Seeland, 1985). A combination of paleocurrent data and interpretations of the internal fill in the southern portion of SB suggests a local current sense trending northwest-southeast and a possible direction trending southeast. Significant normal faulting affects the northern part of Slim Buttes and limited pale-current data from this locality suggests that the current direction is sub-parallel to faulting, inconsistent with the assumed regional paleo-slope (northeast). A broad view of modern erosional patterns reveals a lineament with ridges and valleys also trending northwest-southeast, introducing the possibility that modern erosive patterns may be a rough analogue for paleo-erosion. A suite of paleo-current data was analyzed, in addition to field observations to provide a well understood locality to constrain future work for those interested in the paleogeography of the northern Great Plains.