Midcontinent Geoscience 2023-08-01T09:34:08-05:00 Tony Layzell Open Journal Systems <p>Midcontinent Geoscience is an open-access, peer-reviewed publication of the Kansas Geological Survey. The journal publishes original research on a broad array of geoscience topics, with an emphasis on the midcontinent region of the United States, including the Great Plains and Central Lowland provinces.</p> <p>Benefits to authors:</p> <ul> <li>Free for authors</li> <li>No page or color figure charges</li> <li>Online, open-access publishing</li> <li>Author retains full copyright</li> <li>No limits on pages, figures, or tables</li> <li>Professional editing by the KGS technical editor</li> <li>Pages crawled daily by internet search engines for quick visibility</li> </ul> <p>We are now accepting submissions for the next volume of <em>Midcontinent Geoscience.</em></p> <hr /> <p>As of January 2020, <em>Midcontinent Geoscience</em> replaced the previous Kansas Geological Survey geoscience journal, <em><a href="">Current Research in Earth Sciences</a>. </em></p> <hr /> Salt Dissolution in the Permian Flowerpot and Blaine Formations Defines Limits of the Syracuse Basin in Western Kansas and Eastern Colorado 2023-03-08T14:20:23-06:00 Kenneth Johnson Glenn H. Timson <p class="p1">The Syracuse Basin is a large region of about 8,100 mi<sup>2</sup> (21,000 km<sup>2</sup>) in western Kansas and eastern Colorado that is underlain by Permian-age salts in the Flowerpot and Blaine Formations of the Nippewalla Group. Originally thought to be a structural or depositional basin, detailed study around the perimeter of the basin shows that it is a dissolutional remnant wherein the salt beds are dissolved at all places around the basin’s margins. The two main salt units, the Flowerpot salt and the middle Blaine salt, consist mainly of displacive halite in red-brown shales and siltstones (mudstones). The Flowerpot salt is generally 200–300 ft (61–91 m) thick within the basin, but where most or all of the salt is dissolved outside of the basin, equivalent strata are 50–150 ft (15–46 m) thick. The younger middle Blaine salt is typically 45–60 ft (14–18 m) thick in the basin, and equivalent strata are 5–10 ft (1.5–3 m) thick where the salt is dissolved.</p> <p class="p1"><span class="s1">Five areas selected for detailed study of the dissolution zone around the perimeter of the Syracuse Basin show that removal of about 250 ft (76 m) of Flowerpot salt occurs within horizontal distances ranging from about 930 ft (283 m) to as much as 14 mi (23 km). Structural cross sections show that sub-salt strata dip gently and uninterrupted beneath the dissolution zone, whereas strata above the salt are disrupted and are flexed down by an amount roughly equal to the amount of dissolved salt. This supports the thesis that the salt deposits are a dissolutional remnant and not a structural or depositional basin. In most areas, descending unsaturated groundwater dissolves the shallower middle Blaine salt first and then dissolves the deeper Flowerpot salt. But in two areas, unsaturated groundwater is sourced from a sub-salt aquifer, causing dissolution of the Flowerpot salt first and then the shallower middle Blaine salt.</span></p> <p class="p1">Salt dissolution occurred at different times in different parts of the Syracuse Basin. In most areas, it occurred mainly during the Pliocene–Pleistocene–Holocene Epochs, but locally it started before deposition of the Cretaceous or even from Late Permian through Early Cretaceous time.</p> <p class="p1">The original extent of the Flowerpot and middle Blaine salts went far beyond the current extent of the Syracuse Basin. Remnants of both salt units are present in six large regions that extend from the Denver Basin in northeast Colorado and western Nebraska on the north to the Anadarko and Palo Duro basins in Oklahoma, Texas, and New Mexico on the south, a total area of about 115,800 mi<sup>2</sup> (300,000 km<sup>2</sup>). In all these regions, the two salt units have dissolutional limits like those at the perimeter of the Syracuse Basin.</p> <p class="p1">Dissolution of subsurface salt units can cause problems when or if underground cavities become so large that the roof of the cavity collapses and the cavity rises to the land surface to form a sinkhole or an area of ground subsidence. Problems can also arise when seismic-reflection surveys cross a dissolution boundary and false images of phantom structures are created in strata below the dissolution zone. Also, drilling through salt units must be done with care so that unsaturated drilling muds and formation waters do not cause cavity development in the salt. Dissolution of salt also can affect the quality of groundwater: Salt-dissolution brine can migrate into fresh groundwater aquifers and even render the water unusable for most purposes.</p> 2023-07-28T00:00:00-05:00 Copyright (c) 2023 Kenneth Johnson, Glenn H. Timson Monitoring Changes in Groundwater Resources Due to Increased Surface Water Delivery Efficiencies in the Lower Republican River Basin 2023-08-01T09:34:08-05:00 Andrea Brookfield Anthony Layzell Tingxuan Zhou Boyao Tian <p class="p1">Groundwater and surface water, including such engineered surface water bodies as irrigation canals and drainage ditches, are connected. As such, changes to the management of these surface water bodies will affect interconnected groundwater systems as well. In the Lower Republican River Basin in Kansas, United States, a regional irrigation district has converted several irrigation canals to buried pipe to reduce water lost to evapotranspiration and groundwater recharge, increasing the delivery efficiency of its system. The objective of this work was to investigate the change in local groundwater levels due to this conversion. Seven existing wells in the vicinity of converted or soon-to-be converted irrigation canals were equipped with pressure transducers, and hourly water-level measurements were collected over several years. Average water levels decreased in all wells post-conversion compared to measurements taken between 1970 and 2001. The water levels did not decrease equally, and in several wells, the water-level variance also changed from pre- to post-conversion. It is hypothesized that the observed changes are controlled by many factors, including those related to canal conversion (proximity to the converted canal and time since canal conversion), proximity to other surface water features such as the main stem of the canal and reservoir, and subsurface characteristics that influence the rate of infiltration from precipitation events. This research highlights the interconnectedness of surface and subsurface water resources and how water management decisions need to consider how these interactions may change to support sustainable water use.</p> 2023-12-20T00:00:00-06:00 Copyright (c) 2023 Andrea Brookfield, Anthony Layzell, Tingxuan Zhou, Boyao Tian