Illinois Geologic Quadrangle Map IGQ Saline Mines-BG Bedrock Geology of Saline Mines Quadrangle Gallatin and Hardin Counties, Illinois F. Brett Denny, Joseph A. Devera, and Adam Kittler 2013 Prairie Research Institute ILLINOIS STATE GEOLOGICAL SURVEY 615 East Peabody Drive Champaign, Illinois 61820-6964 (217) 244-2414 http://www.isgs.illinois.edu © 2013 University of Illinois Board of Trustees. All rights reserved. For permission information, contact the Illinois State Geological Survey. Introduction Graben. The fault bifurcates to the southwest along Peters Creek into several parallel faults that are difficult to trace. This report accompanies a geologic map of the Saline Mines The northeastern extension appears to merge into a single 7.5-minute Quadrangle. The Saline Mines Quadrangle was fault that can be traced into the alluvial sediment of the Ohio included on previous geologic maps by Weller et al. (1920), River. Kehn (1974) mapped faults that appear to line up with Butts (1925), Weller (1940), Weller et al. (1952), and Baxter the Peters Creek Fault in the Kentucky portion, an adjacent et al. (1963). Reports on the Illinois-Kentucky Fluorspar quadrangle. Exposures of this fault zone are few, but mineral District (IKFD) and mines were completed by Bastin (1931), exploration tests have intersected the fault at Sec. 23, T11S, Heyl and Brock (1961), Heyl et al. (1974), Brecke (1962), R9E (SW¼) and near the center of Sec. 6, T12S, R9E. The and Hutcheson (1973). A map of the coal mines of this fault is mineralized in places, but no commercial develop- quadrangle was completed by Myers and Chenoweth (2009). ment for minerals is known along its length in this quad- Original geologic mapping for this project was completed in rangle. 2011 and 2012. Hogthief Creek Fault Zone Structure and Tectonics This fault zone demarcates the northwest edge of the Rock Creek Graben and is also poorly exposed. Fractured beds The map area lies within the Fluorspar Area Fault Com- were observed at several locations, but exposures of the fault plex, one of the most intricately faulted areas in the North surface were not observed. The Hogthief Creek Fault was American interior (Denny et al. 2008). Although reverse, mapped by Weller et al. (1920) and Baxter et al. (1963) as strike-slip, and oblique-slip faults are important, high-angle a complex series of parallel faults merging into two paral- normal faults prevail. Seismic reflection profiles reveal that lel faults near Rock Creek. A segment of the fault appears faults originate in the Precambrian basement and bifurcate to be connected to the Goose Creek Fault Zone to the north. upward, and the fracture pattern becomes more complicated Although no commercial development for minerals is known toward the surface (Potter et al. 1995). As mapped from along this fault zone, a piece of limestone replaced with fluo- outcrop data, faults are clustered into zones, which may rite was observed in a creek near the center of Sec. 20, T12S, outline horsts and grabens. Some faults in this region are R9E just west of the unnamed prospect pit. We mapped a mineralized with fluorite, and horizontal strata-bound fluo- fault along this area merging into the Goose Creek Fault rite is present near major fault blocks. This quadrangle lies Zone to the north. along the eastern flank of a regional igneous arch called the Tolu (or Kutawa) Arch (fig. 1). Regional dip and some of the Goose Creek Fault Zone faulting is inherently related to this regional igneous activity. The Goose Creek Fault Zone lies northwest of the Rock Creek Graben. The Goose Creek Fault Zone is a series of Maximum displacement in the Saline Mines Quadrangle is parallel normal faults showing as much as 700 feet of verti- along the Rock Creek Graben, where Lower Chesterian units cal offset (Nelson 1995). This fault zone can be seen along are juxtaposed with the Lower Pennsylvanian Caseyville the road cut near the Goose Creek Mine. Vein fluorite miner- Formation, producing more than 1,000 feet of vertical offset. alization is present along portions of the Goose Creek Fault The fault segments here are extremely complex, and, in Zone. Several drill holes verify the location of the faults near many cases, rock units that occupy narrow fault slices cannot the Green and Hoeb Mines (Sec. 16 and 17, T11S, R9E). be identified with confidence. The authors have conducted This fault can be projected to the northeast under the flood- field work in these complexly faulted areas and have utilized plain of the Ohio River. Kehn (1974) mapped a fault on the mineral exploration borings to assist with structural interpre- Kentucky side of the Ohio River that may project into this tations. Nevertheless, these fault zones are probably more fault zone. Tracing this fault zone to the northeast is difficult. complex than we depict on this geologic map. Stratigraphy Rock Creek Graben The Rock Creek Graben bisects the Saline Mines Quad- The bedrock exposed in this area ranges from Mississip- rangle from the southwest corner of the quadrangle trending pian to Pennsylvanian. The nomenclature for these units has in a northeasterly direction. The graben is approximately 2 changed through time, which complicates the stratigraphy. miles wide and can be traced to the Saline River, where the The current stratigraphic nomenclature can be viewed on the structure is projected under the floodplain of the Ohio River. graphic column, and the previous stratigraphic nomenclature The Hogthief Creek Fault Zone and Goose Creek Fault is well documented by Baxter et al. (1963). Baxter et al. Zone bound the northwest edge of the graben, and the Peters (1963) also suggested that several hundred feet of Pennsyl- Creek Fault Zone bounds the southeast side. vanian McLeansboro Group sediments may be present in the downdropped Rock Creek Graben under the floodplain of Peters Creek Fault Zone the Ohio River. More data are needed in this area to decipher This fault zone extends across the Saline Mines Quad- its Pennsylvanian stratigraphy. rangle and demarcates the southeast edge of the Rock Creek 1 Harrisburg Tertiary and Cretaceous Cretaceous Mvu TKu undivided and Tertiary ) ) ) &t ) Unconformity ) ) ) ) Igneous diatremes &c &cv ) Permian (igneous) Mc Igneous dike showing trend &cv Unconformity ) &t &c Carbondale Formation &c &t Tradewater Formation Pennsylvanian ) &cv &t Caseyville Formation ) Unconformity Mc Chesterian undifferentiated &t ) &t Mvu Upper Valmeyeran Mississippian Mvl ) Mc Lower Valmeyeran &cv &c Du Devonian undifferentiated Devonian ) Mc & cv Fluorite subdistrict ) Mvu &t x Mc &cv Fluorite mine x x is and x Harr IL-KY Fluorite District e Goose Creek r &t i Du p &cv Mvl k c Fault m o E x -R n Anticline &cv -i Mc e x av C Graben x Mc k Creek Graben · Mc &cv Roc Mc ) ) ) High-angle reverse fault e Cave- t at xx r t x rs in-Rock &cv a te x w In Pc e x t x S x x e r T x olu la Arch ic s o x R &t Rosiclare Mvu Mc xx S s &cv I Y g &cv in O K r C & p N cv S I U x x n e L T x x re d L o n I N d e o tt Mc E x m i om r Marion K x C C s x l ia x il v x e H x & L s cv r e x y D l x x il Salem H re k o ic o L M y la &t &cv C &cv x x Mexico TKu x Tabb x x Fredonia x x Mvl x Tabb Mvu x xxMvl Mvu TKu Mc Princeton Eddyville Mvl Mvu TKu Mvl Mc 0 5 Calvert City Miles Mvl TKu Figure 1 Geologic map of the Illinois-Kentucky Fluorite District. Edited from Denny et al. (2008). 2 Bethel Ss Ore Horizon Bethel Ss Downeys Bluff Ls Enlargement 0 30 below Feet Base of Bethel Sandstone Purple Replace ment Flu Argillaceous orspa r Partings Decalcifie d Beds Pu rple Rep lacem ent Flu or sp ar Downeys Bluff Ls Downeys Bluff Ls Not to scale Figure 2 V-shaped structure, S.E. Oxford Mine, “Bethel Level” ore horizon. Adapted from Brecke (1962). Black areas and bands show acid spar (95% CaF2) accumulations. Mineral Resources galena. Some deposits contained small amounts of silver in the galena and recoverable cadmium and germanium in The IKFD (fig. 1) was formerly the leading source of fluorite the sphalerite (Trace and Amos 1984). Galena was found in in the United States and also produced significant quanti- abundant amounts at Lead Hill and portions of the Cave-in- ties of lead, zinc, and other commodities. The term fluorspar Rock subdistrict. The amount of silver in the lead was esti- is commonly used as a synonym for fluorite. Economic mated to be 5 to 8 ounces per ton (Bastin 1931). The amount mineralization in the IKFD is predominantly composed of fluorite and lesser amounts of sphalerite, barite, and galena. Other minerals identified in this district include pyrite, chal- copyrite, quartz, celestite, cerussite, greenockite, malachite, Bethel Ss smithsonite, witherite, strontianite, benstonite, and alstonite (Goldstein 1997). Ore bodies are of three types: (1) bedded Bedded Fluorite replacement deposits that formed by selective replacement of limestone strata, (2) vein deposits along faults and frac- Downeys Bluff Ls tures, and (3) residual deposits derived from veins or beds. 10 eet) The best indication of bedded replacement is remnant tical (f r textures of limestone observed within fluorite crystals. 0 Ve 40 20 0 These include fossils, stylolitic sutures, primary bedding, Horizontal (feet) and other sedimentary structures. Mine-run ore commonly contained 30 to 40% fluorite, as much as 2 to 3% zinc, and Figure 3 Stratiform or bedding replacement.