Tectonic implications and influence of the Midcontinent Rift System in Nebraska and adjoining areas

Abstract

Southeastern Nebraska is underlain by EarlyProterozoic rocks of the Central Plains (1,600 to 1,800 Ma) and Penokean (1,830 to 1,890 Ma) Provinces. The Midcontinent Rift System was imposed upon and reflects the preexisting tectonic grain of the older basement. During Paleozoic time several periods of structural change occurred related to the Midcontinent Rift System. In the same geographic area, there was successive development of the Southeast Nebraska arch, the North Kansas basin, the Nemaha uplift, and the Table Rock arch. The locations of these regional features were controlled by the patterns established by rift tectonics. Features such as the Eastern Nebraska high, the Abilene Anticline, the Union fault, and the Burchard fault are reactivations of specific rift features.

Joint and Lineament Patterns across the Midcontinent Indicate Repeated Reactivation of Basement-Involved Faults

“…The effects of local tectonics during the Infracambrian and the Paleozoic are observed from stratigraphic relationships, thickness changes, and multiple unconformities within the Cambrian-Permian succession, particularly in the present study area (Figure 3; [27,37,41,47]). The Cambrian-Devonian succession is chiefly composed of dolomite, with some clastic units; these clastic materials may indicate periods of land exposure and influx of eroded material to an area otherwise covered by a shallow sea [36,48].…”

“…The Mid-Continent Rift System is considered an aulacogen, and has a counterpart failed rift arm to the east. The Nebraska segment of the Mid-Continent Rift System parallels fabrics within the earlier Central Plains Orogen [35]. In the southern part of the study area, within eastern Kansas, the Mid-Continent Rift System is cut by a series of NW-SE trending dextral strike-slip faults, on which there have been historical earthquakes [39,40].…”

“…The earliest crust in southeast Nebraska and northern Kansas is considered to date from the Central Plains Orogeny (Figure 2) around 1.9-1.7 Ga [35]. In the area of interest, the upper crust is composed of quartzite with granite intrusions (e.g., [36,37].…”

“…In the southern part of the study area, within eastern Kansas, the Mid-Continent Rift System is cut by a series of NW-SE trending dextral strike-slip faults, on which there have been historical earthquakes [39,40]. These faults appear to form an accommodation zone between the Nebraskan and Kansan segments of the Mid-Continent Rift System ( Figure 2) and may be related to the boundary of the Central Plains Province or the suture between this province and the Penokean province which is located to the southeast of the Mid-Continent Rift System [35,41,42]. The structures are also aligned along the same trend as the Missouri Gravity Low which underlies the accommodation zone as well as additional NW-SE trending lineaments interpreted from gravity and magnetic data [43].…”

“…A major tectonic event, making the proto-Nemaha Uplift emergent, is documented in the Ordovician [37,53,54]. The Kansas segment of the Mid-Continent Rift System may have been reactivated in the latter part of the Paleozoic, forming the Abilene, Voshell, Barneston, and Nemaha anticlines along the eastern edge of the Mid-Continent Rift System [35,55]. Rift segments are also considered to be reactivated in the formation of the Union fault and related faults of the study area [27,41].…”