5 14.GS: :iR226 :. 1 ILLINOIS GEOLOGICAL SURVEY LIBRARY STATE OF ILLINOIS WILLIAM G. STRATTON, Governor DEPARTMENT OF REGISTRATION AND EDUCATION VERA M. BINKS, Director 'a %& GYPSUM AND ANHYDRITE IN ILLINOIS Donald B. Saxby J. E. Lamar DIVISION OF THE ILLINOIS STATE GEOLOGICAL SURVEY JOHN C. FRYE, Chief URBANA CIRCULAR 226 1957 Digitized by the Internet Archive in 2012 with funding from University of Illinois Urbana-Champaign http://archive.org/details/gypsumanhydritei226saxb GYPSUM AND ANHYDRITE IN ILLINOIS Donald B. Saxby and J. E. Lamar ABSTRACT Information that could be of value in the possible future eco- nomic development of gypsum and anhydrite deposits in Illinois has been collected from well data and assembled in this report. The gypsum and anhydrite occur in the St. Louis limestone formation. They do not crop out and are restricted to the southern half of Illi- nois. In the deeper parts of the Illinois structural basin anhydrite prevails, but along the shallower marginal area extending roughly from Madison County to Sangamon County both gypsum and anhy- drite occur. In general the amount of gypsum present increases with decreasing depth. The minimum depth at which gypsum and anhydrite were found was 470 feet. The maximum thickness of gypsum, devoid of other materials, encountered in six diamond drill cores from southwestern Illinois, was 2 feet at a depth of 896 feet, but 3 1/2 feet of material averag- ing 93 percent gypsum was found in another core at 722 feet. Cable tool and rotary drill data are less specific but suggest similar or greater thickness of gypsum. All available data regarding the presence of gypsum result from drilling for water, coal, or oil, and thus it is possible that drilling specifically directed to the discovery of gypsum might find greater thicknesses of this mineral than have thus far been reported. INTRODUCTION Gypsum or anhydrite beds are not known to crop out in Illinois, but both minerals have been encountered in wells in the St. Louis limestone formation in the southern half of Illinois at depths ranging from 470 to 3390 feet. Infor- mation on some of these occurrences was given in an Illinois State Geological Survey report (Lamar, 1938), now out of print. Since that report appeared, additional information has accumulated and the present report incorporates both old and new data on the nature and extent of the Illinois deposits and makes the information regarding them available for consideration in the light of pres- ent and future economic conditions. Abandoned coal mine shafts are present in parts of the area where the gypsum and anhydrite occur. There is a possibility that some of these shafts could be rehabilitated to save part of the cost of sinking a shaft to the gypsum or anhydrite beds. [1] ILLINOIS STATE GEOLOGICAL SURVEY Fig. 1. - Index map of counties. GYPSUM AND ANHYDRITE IN ILLINOIS 3 PROPERTIES OF GYPSUM AND ANHYDRITE Gypsum is a soft mineral consisting of hydrous calcium sulfate and has the chemical composition CaS04'2H20. When suitably heated or "calcined" its composition can be changed to CaS04- 1 /2H2O, a product known as plaster of Paris. When mixed with water, plaster of Paris reverts to CaS04-2H20 and hardens or "sets." This characteristic is the basis for many of the uses of gypsum. Anhydrite is harder and heavier than gypsum. It is anhydrous calcium sulfate and has the chemical composition CaS04. Because it does not contain water it cannot be processed to yield plaster of Paris. USES OF GYPSUM AND ANHYDRITE Gypsum has many uses (U. S. Bureau of Mines, 1955). Uncalcined, it is used as, among other things, a portland cement retarder, as agricultural gyp- sum, as a filler, as rock dust, in brewer's fixe, and in color manufacture. Calcined, gypsum is used in industry in the manufacture of plate -glass and terra cotta plasters, pottery plasters, orthopedic and dental plasters, stat- uary, industrial casting and molding plasters, deadburned filler, and for mis- cellaneous uses. In the building materials field, gypsum is used for Keene's cement, for various plasters (such as insulating, roof-deck, joint-filler, patching, and painters'). It also is used to make prefabricated lath, wallboard, laminated board, sheathing board, and tile. Ground anhydrite is used in southern states as a soil conditioner in peanut growing (North, 1956). In Europe anhydrite is employed for making sulfuric acid and cement (Goudge, 1951) and it has been used in ammonium sulfate man- ufacture (Cole and Rogers, 1933). PRODUCTION STATISTICS In 1952 the crude gypsum mined in the United States totalled 8,415,300 short tons and had a value at the mines of $22,896,051, or $2.72 per ton (U. S. Bureau of Mines, 1955). Eight states had three or more active gypsum mines - California, Colorado, Iowa, Michigan, Nevada, New York, Oklahoma, and Texas. No production of anhydrite was reported for 1952. GENERAL GEOLOGY OF ILLINOIS GYPSUM AND ANHYDRITE Gypsum and anhydrite beds are found principally in the St. Louis limestone formation of Mississippian age. In some places only one bed is found, in others two or three beds. The existence of three appears to be relatively common but it is not known whether they are stratigraphic equivalents or how the three beds correlate with the occurrences of two beds or a single bed. The term "evapo- rite zone" is used in this report to describe the strata between the shallowest and deepest occurrences of gypsum and anhydrite. The term "evaporite" is used to refer to gypsum or anhydrite without distinction and relates to the prob- able direct or indirect role of evaporation in their formation. The depth at which gypsum and anhydrite beds are encountered is partly, especially locally, a function of the topographic elevation of the ground surface. However, the gradual eastward and southeastward increase in the depth of the 4 ILLINOIS STATE GEOLOGICAL SURVEY beds in the western part of southern Illinois is related to the down-warping of the bedrock strata towards the center of the Illinois basin, a large roughly north-south basin whose deepest part is in White County. East of the center of the basin the strata rise and are locally arched into a fold, called the La- Salle anticline, which is well developed in Clark, Lawrence, and Crawford counties (figs. 1 and 3). Diamond drill core data and other well data given later suggest that below a depth of about 1500 feet the evaporite material in the evaporite zone of the St. Louis formation consists principally of anhydrite. Where the zone is at progressively shallower depths, the percentage of anhydrite decreases and that of gypsum increases, though the change is not necessarily either uniform or everywhere consistent. Limestone and/or dolomite occur with the evapo- rites in varying amounts. Probably there is considerable lateral variation within comparatively short distances in the relative proportions of the various components, but these variations are less common in the deeper anhydrite de- posits than in the shallower gypsum and anhydrite occurrences. CHARACTER AND FORMATION OF ILLINOIS GYPSUM AND ANHYDRITE The gypsum seen in the diamond drill cores and other cuttings generally is colorless, white, or light gray and occurs as relatively coarse tabular crys- tals. Less common are occurrences of white, chalky gypsum. The anhydrite generally is fine-grained and bluish white to light gray, rarely brown, and un- der the microscope is seen to have rectangular cleavage. Some coarsely crys- talline masses of anhydrite were noted. It appears probable that the anhydrite originally was deposited from a sea as a result of evaporation. Some of the gypsum may have been similarly de- posited and some of it is an alteration product of the anhydrite. Studies of thin sections (D. L. Biggs, personal communication, 1956) from samples at depths of 1034, 1038, 1039, 1052, and 1053 feet, core C-153, described subsequently, lead to the conclusion that the alteration probably was done by groundwater be- cause some crystals of anhydrite have margins altered to gypsum that is in optical continuity with the anhydrite. Other anhydrite crystals are altered to gypsum along their cleavage planes. The gypsum rarely contains isolated car- bonate crystals but reveals many included fragments of anhydrite crystals. That there was probably also some secondary redistribution of anhydrite is apparent because anhydrite occurs as fissure -filling veins in dolomite and as large crystals and irregular masses replacing dolomite. It also replaces the calcite of limestone and occurs as irregular masses in this rock. The an- hydrite veins contain fragments of carbonate crystals, and other types of an- hydrite occurrences show isolated carbonate crystals that are locally abun- dant. CHEMICAL ANALYSES Chemical analyses were made of two samples of gypsum and three sam- ples of anhydrite to obtain specific information regarding their composition. Results of tests are shown in table 1. GYPSUM AND ANHYDRITE IN ILLINOIS ! Table 1. - Analyses of Gypsum and Anhydrite (Analyses by L. D. McVicker in the laboratories of the Illinois State Geological Survey) Gypsum Anhydrite Core C28 Core C28 Core C28 Core C28 Core C1807 Depth Depth Depth Depth Depth 918-923' 896-898' 905-912' 1017-1024' 1260-1264' Si0 2 and insoluble 1.46 0.68 0.50 1.14 0.50 Fe 2 3 and A1 2 3 0.16 0.18 0.10 0.16 0.04 MgO 1.14 0.28 0.60 1.86 0.18 CaO 33.64 32.76 40.86 40.26 41.06 NaCl 0.34 0.69 0.38 0.15 0.26 co 2 2.04 0.28 0.37 3.93 1.04 SO3 45.88 45.88 57.10 52.50 56.34 Free watei 0.01 0.01 0.01 0.01 0.01 Comt lined ' water 16.04 20.23 0.69 0.46 1.23 TYPES AND SIGNIFICANCE OF WELL DATA Three types of well data have been used in this investigation - a) diamond drill core data, b) cable tool or rotary drill data based on samples saved dur- ing the drilling of wells and subsequently studied by Survey geologists, and c) drillers' records of formations encountered in cable tool or rotary drill bor- ings. Although there is considerable variation in the significance of the data from these three sources, all are meaningful in indicating the probable thick- ness, distribution, and depth of the evaporite zones, and are so used. The pos- sibility of error, as indicated below, should, however, be borne in mind when the data are used. Of the three types of data mentioned above, that from diamond drill cores is regarded as the most detailed. The cuttings from cable tool and rotary drill wells afford only rough quantitative data regarding the mineral composition of the strata penetrated and do not give details on the manner in which limestone or dolomite may be interbedded in the strata represented by some samples. Comparison of several drillers' logs and older sample study logs with the cut- tings from the same wells indicates that a distinction between gypsum and an- hydrite has not always been made and that the term gypsum was commonly used to describe both materials. As a result, some well data of this type indicated considerable thicknesses of gypsum that actually is anhydrite or a combination of gypsum and anhydrite. The detail with which small percentages of limestone or dolomite in the gypsum or anhydrite are reported also is probably variable and some, perhaps many, gypsum zones may in reality also contain limestone, dolomite, or anhydrite partings or beds. COMPARISON OF VARIOUS TYPES OF WELL DATA Three Sangamon County wells drilled within a mile of each other by differ- ent methods afford an opportunity for comparing the types of data resulting from cable tool, rotary, and diamond drilling (fig. 2). All three show gypsum ILLINOIS STATE GEOLOGICAL SURVEY CABLE TOOL ROTARY DRILL DIAMOND DRILL CORE KEY Wells used (oil in Sangamon Co.): 1. Perardi No. I Goldstein IO-I5N-3W 2. Dovis No. I Toft I5-I5N-3W 3 Miller No. I Somple II-I5N-3W .... 5 Gypsum Anhydrite Dolomite Sandstone Shale Cherty Argillaceous Oolitic Silty Sandy Fig. 2. - Results of studies of a diamond -drill core and of cuttings from a cable-tool well and from a rotary-drill well, all within a mile of each other. A self -potential curve for the rotary well is shown to its left with resistivity curve to its right. GYPSUM AND ANHYDRITE IN ILLINOIS 7 and anhydrite zones at approximately the same depth but there is considerable variation in the amount of detail. It is possible that some of the differences between the logs are real, but it is likely that many of the variations relate to the exactness with which the materials recovered from the wells reflect the character of the evaporite beds penetrated. The diamond drill cores gave the maximum information, followed by the cable tool cuttings and then the rotary drill cuttings. SIGNIFICANCE OF ELECTRICAL RESISTIVITY DATA To the left of the rotary drill well record in figure 2 is the self -potential curve for the well. No certain reflection for the evaporite zones is evident. To the right are resistivity curves with electrode spacings of 18 and 54 inches. The marked increase in resistivity, indicated by the deflection of both resis- tivity curves to the right at the evaporite zones, suggests that resistivity meas- urements may be helpful in locating such zones where other types of data are lacking. THE ST. LOUIS FORMATION EVAPORITES The occurrence of gypsum and anhydrite in the St. Louis formation is treated by a series of maps (figs. 3-6). All the well data used in making these maps are based on core and sample studies. In some areas where there were a great many wells, only selected records were used to avoid crowding the map. The St. Louis formation is of lower Mississippian age and consists almost entirely of limestone. It crops out in western, southwestern, and extreme southern Illinois but the outcrops contain no evaporites. The formation varies in thickness, as shown in figure 3, and ranges from to more than 450 feet thick. It is absent in the northern half of Illinois. There is no well defined re- lationship between the thickness of the St. Louis formation and the thickness of the evaporite beds or of the evaporite -bearing zone. Figure 4 shows the depth to the top of the evaporite zone. In general the depth increases from the northern margin of the zone towards the center of the Illinois structural basin and is greatest in eastern Jasper, eastern Rich- land, western Clay, and central Wayne counties. The shallowest area occurs in Madison County and parts of adjacent counties where a minimum depth of 470 feet is recorded. The total thickness of the various evaporite occurrences in the St. Louis formation is shown in figure 5. Maximum thicknesses are shown in a band ex- tending northeast, roughly from East St. Louis. The map indicates further the character of the evaporites as reported in the well logs used in making the map. Except in the case of diamond drill borings, these data are subject to the qualifications previously mentioned regarding the accuracy of the interpre- tation of rotary and cable tool drill cuttings. The thickness of the evaporite -bearing zone of the St. Louis formation is indicated in figure 6. The data given are the thicknesses between the shallow- est occurrence and the deepest occurrence of the evaporites in the wells plot- ted on the map. The figures generally do not denote a continuous body of evap- orites of the thickness shown although this may be true for some wells. The ILLINOIS STATE GEOLOGICAL SURVEY Limit of uneroded St. Louis formation Line showing thickness of the St. Louis formation, interval 50 feet SCALE 10 20 30 miles — I I Fig. 3. - Thickness of St. Louis formation. GYPSUM AND ANHYDRITE IN ILLINOIS Small Anhydrite Occurrences .1221 T i KEY Type Of Boring • Rotary a Cable o Diamond drill — Limit of uneroded St. Louis formation _ Northern limit of evaporite- bearing area Probable southern limit of major evaporite area 2 QOO-^^- [ne s h° win g depth to top of evaporite zone, interval 100 feet i 2900 \ \ 1 | j i i i / / i ? C \ if \ i J SCALE 10 20 30 miles 3 Fig. 4. - Depth to top of St. Louis evaporite zone. 10 ILLINOIS STATE GEOLOGICAL SURVEY 7.1 . 2.1 " 4.8 -10- Type Of Boring • Rotary A Cable ° Diamond dril Limit of uneroded St. Louis formation Northern limit of evaporite- bearing area Probable southern limit of major evaporite area Total thickness of gypsum encountered Total thickness of anhydrite encountered Total thickness of evaporite encountered Line showing total thickness of all evap- orite deposits encountered, interval 10 feet miles Fig. 5. - Thickness and types of evaporites in the St. Louis formation. For some wells only a figure above a horizontal line is given, others have only a figure below the horizontal line. The absence of a figure above the line indicates the absence of gypsum, the absence of a figure below the line shows the absence of anhydrite. GYPSUM AND ANHYDRITE IN ILLINOIS 11 Type Of Boring • Rotary A Cable Diamond dri Limit of uneroded St. Louis formation Northern limit of evaporite bearing area Probable southern limit of major evaporite area Line showing thickness of evaporite-bearing zone, interval 50 feet 30 miles Fig. 6. - Thickness of the evaporite-bearing zone in the S. Louis formation. South of the major evaporite area only minor amounts of evaporites are present locally. 12 ILLINOIS STATE GEOLOGICAL SURVEY x: x: H -X £ ■»-> a> a> M 4) -* M o — ■»-> e c tt) Q. 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C 'rt Q ^H 0) S N O O — 1 >• 0) M — 1 CC O "J S CT> ID ID 01 u x: e ro H M 01 "O 14-. CD U. ro >- a> +j M T) C ^4 X ro H TO • tt) T3 ro 3 • • tt) ro x: -) O < ironQh in * * CC —i a> cc u u CJ cc cc O cc II < —1 +J tt) O or 2Z ^cMcotinvor-oo -°ra GYPSUM AND ANHYDRITE IN ILLINOIS 13 maximum thickness of the evaporite zone is 234 feet and occurs in southern Cumberland County. In general the thickest portion of the zone forms an arc opening to the south and bordering the northern boundary of the area of evap- orite deposits. The position of the evaporite zone in the St. Louis formation is shown in figure 7. The zone is restricted to the lower one -half or three -fifths of the St. Louis formation. However, the distribution of specific evaporite occur- rences within the lower St. Louis formation is sporadic. Data on Specific Wells The areas wherein the evaporite beds are shallowest and contain most gypsum occur, as has been shown, in Bond, Christian, Madison, Macoupin, Montgomery, and Sangamon counties in western and central Illinois. All dia- mond drill cores in Survey files from these counties have been examined in detail and are reported in part 1 of the appendix. A similar study was made of representative well cuttings in the Survey's possession from the same coun- ties. Part 2 of the appendix gives the records of all wells studied in which at least one sample contained 25 percent or more gypsum. One record having only one sample containing 20 percent gypsum is included because there was no anhydrite associated with the gypsum. Diamond Drill Core Data Eight diamond drill cores penetrating gypsum and anhydrite were avail- able for study. Composition of the cores as reported is based on visual esti- mates, a sufficient number of which were checked by microscopic and x-ray examinations to warrant the belief that they are reasonably correct. The max- imum thickness of gypsum encountered, devoid of any other materials, was two feet in core C28 at a depth of 896 feet. However, core C141 had 42 inches of material averaging 93 percent gypsum at a depth of 722 feet to 725 feet 6 inches, core C153 had 26 inches averaging 92 percent gypsum at 1025 feet 1 inch to 1027 feet 2 inches, and core C28 had 60 inches averaging 83 percent gypsum at a depth of 918 to 923 feet. Cable Tool and Rotary Drill Data No samples in the cable tool and rotary drill borings studied were 100 per- cent gypsum. However, the minimum thickness represented by any sample was five feet, so it is possible that beds of gypsum free from anhydrite, lime- stone, or dolomite and less than five feet thick might be present but would not be distinguished in the cuttings. Contamination of the cuttings from overlying strata may be involved also. Well 6129 in Madison County penetrated a 10- foot thickness of material consisting of 85 percent gypsum and 15 percent cherty limestone at a depth of 700 to 710 feet. Well 19,477 in Sangamon County encountered at 890 to 903 feet a 13-foot thickness. of rock composed of 65 per- cent gypsum and 35 percent anhydrite, limestone, and dolomite. In Montgomery County well 5232 went through a 15-foot thickness consisting of 55 percent gyp- sum, 10 percent anhydrite, and 35 percent dolomite at a depth of from 1165 to 1180 feet. In the same county, well 4832 found 5 feet of material that was 60 percent gypsum, 5 percent anhydrite and 35 percent limestone at 980 to 985 feet. 14 ILLINOIS STATE GEOLOGICAL SURVEY Bond County well 3843 found at 1080 to 1090 feet a 10-foot thickness of gypsum and limestone in equal amounts. Additional Data The Survey has in its files cuttings from many wells that have not been studied because of the magnitude of the work involved. This is especially true of cuttings from wells in a number of oil fields within the area considered in this report. These well cuttings are available for examination in the Survey laboratories. EVAPORITES IN OTHER FORMATIONS Other major occurrences of anhydrite in formations other than the St. Louis limestone are to be found in the Ordovician dolomites and limestones, ranging from a minimum depth of 1768 feet in Randolph County to a maximum of 7683 feet in White County. In Fayette, Randolph, Perry, Jackson, and Law- rence counties, anhydrite is found mainly in the Joachim-Dutchtown dolomite. In White County near Grayville a study of the Superior -Ford C-17 diamond drill core showed anhydrite in the Dutchtown and Knox dolomites as follows. Composition (%) Anhydrite Dolomite 50 50 15 85 2-4 96-98 3-5 95-97 The anhydrite is for the most part very finely crystalline, although some of it is coarsely crystalline. It is dark bluish to brownish gray. ECONOMIC POSSIBILITIES The data in this report do not demonstrate the existence of commercial deposits of gypsum in Illinois but they are worthy of consideration if for no other reason than because of the proximity of the gypsum occurrences to a ma- jor market area, that of greater St. Louis, which is being supplied from more distant sources. It is noteworthy that none of the wells whose records have been used in the preparation of this report were drilled for the purpose of finding gypsum. Con- siderable areas that may contain gypsum have not been explored. Thus it is possible that borings located at suitably selected places might find gypsum at shallower depths and in greater thicknesses than are reported herein. It is significant also that the greatest thicknesses of gypsum noted occur at com- paratively shallow depths where the possibilities for the hydration of anhydrite to gypsum appear to be better than they are at greater depths. These two con- siderations suggest that the near outcrop areas northeast of East St. Louis bear further scrutiny. Thickness Depth (feet) (feet) Dutchtown formation 86 7114-7200 21 7200-7221 33 7221-7254 Glenwood shale St. Peter sandstone Knox dolomite 173 7510-7683 GYPSUM AND ANHYDRITE IN ILLINOIS 15 It has been pointed out that no evaporites crop out in Illinois despite the fact that the St. Louis formation is extensively exposed in western, southwest- ern, and extreme southern Illinois. Evidence that the outcropping beds may have contained evaporites at some time is suggested by the presence of beds of limestone conglomerate or breccia in western and southwestern Illinois at about the same stratigraphic horizons as the unexposed evaporite zone. These conglomerates or breccias may have resulted from the removal of evaporites by solution from deposits of interbedded limestone and evaporites. If this is true, it indicates that the distribution of evaporites in western and southwest- ern Illinois was at one time more widespread than at present and further points to the area as one that may merit specialized investigation for evaporites. REFERENCES Cole, L. H., and Rogers, R. A., 1933, Anhydrite in Canada: Canada Dept. Mines, Mines Branch, No. 732, p. 29. Goudge, M. F., 1951, Gypsum and anhydrite as industrial raw materials: in Conference on Industrial Minerals, Nova Scotia Dept. of Mines and Nova Scotia Research Foundation, p. 30. Lamar, J. E., 1938, Unexploited or little known industrial minerals of Illinois: in Contributions of the Fifth Annual Minerals Industries Conference, Illi- nois Geol. Survey Circ. 23, p. 224. North, O. S., 1956, "Gypsum": in Mineral Facts and Problems: U. S. Bur. Mines Bull. 556, p. 342. U. S. Bureau of Mines, 1955, Minerals Yearbook, v. 1, 1952, p. 485, 489. 16 ILLINOIS STATE GEOLOGICAL SURVEY APPENDIX PART 1 Descriptions of diamond drill cores in Bond, Macoupin, Madison, Mont- gomery and Sangamon Counties. One core from White County is described to show the nature of the evaporites in the deeper parts of the Illinois basin. CORE CI 807 Schwartz and Shell, Studebaker No. 1 SEj SEj SVIf£ sec. 21, T. 6 N., R. 2 W., Bond Co. Estimated composition (%) Thickness (ft.) Bottom depth (ft.) Gypsum Anhydr ite Limestone Dolomite 1 1 4 1259 1260 1264 3 97 8 90 97 3 2 3 1 I265i 1268 1269 5 55 85 15 35 80 10 15 CORE 153 Madison Coal Co., Boring 15 SW cor. NW£ NEj sec. 35, T. 8 N. , R. 6 W., Macoupin Co. Estimated composition (%) Sample Thickness (in.) Bottom depth (ft.) Gypsum Anhydrite Limestone S 35 7 942 , 11" 100* No core 1 943* 0" 37 7 943' 7" 100 38 17 945' 0" 90 lOt No core 4 945' 4" 42 10 946 i 2 " 100* 43A 32 948'10" 80 20t 43B 2 9491 o" 5 95 1 43C 24 951' 0" 95 5t 43D 9 951' 9" 90 10 44 5 952' 2" 5 95 S 57A 17 975 , 11" lOOt 56A 9 976' 8" 8 2 85t 58A 6 977' 2" Trace lOOt 58B 9 977'H" 10 80° GYPSUM AND ANHYDRITE IN ILLINOIS 17 CORE 153 (( :ontinued) Estimated compos ■ it ion {%) Sample Thickness Bottom depth Gypsum Anhydrite Limestone (in.) (ft.) 59 10 978' 9" 60 20 20+ 60-61 13 979' 10" 30 70t 6li 5 980* 3" 100 62 2 980' 5" 10 90+ 63 12 981' 5" 50 25 25° 64A 10 982' 3" 12 85 3 64B 18 983' 9" 98 2 65 19 985' 4" 30 70+ S 76A 21 1012' 9" 10 90 76B 6 1013' 3" 20 60 20 76C 26 1015' 5" 9 90 1 76D 11 1016' 4" 40 35 25* S 80A 24 1021' 5" 12 85 3* 80B 4 1021' 9" 100 80C 5 1022' 2" 3 10 87 80D 18 1023* 8" 10 85 5* 80E 17 1025' 1" 7 90 3 80F 6 1025' 7" 100 80G 3 1025' 10" 50 50* 80H 17 1027* 3" 98 2 801 3 1027' 6" 40 60 Average Compos it ion i Df H: igh Gypsum Zones 37-43D 101 943' 0"- 951' 9»* 78 22 6l-g-64B 47 979' 10" -983 lg» 63 26 11 80F-H 26 1025'1"- 1027 •3" 92 8 * - Argillaceous; + recorded. Dolomite; ° Includes 4" from which no core was CORE CI 54 Madison Coal Co., Boring 16 SEi SEi- SEi sec. 36, T. 8 N., R. 6 W., Macoupin Co. Estimated composition {%) mple Thickness (in.) Bottom depth (ft.) Gypsum Anhydrite Limestone 33 5 955' 5" 20 80 34 10 956' 3" 100* 35A 20 957'11" 80 10 10* 35B 3 958' 2" 40 60 Trace 35C 8 958 '10" 95 5 Trace 35D 5 959' 3" 60 10 30* 35E ok 959' lli" 960 f 3i" 85 3 12* 35F 4 88 10 2 18 ILLINOIS STATE GEOLOGICAL SURVEY CORE CI 54 (continued) Estimated composition {%) Sample Thickness Bottom depth Gypsum Anhydrite Limestone (in.) (ft.) 35G 7 960' lOr" 55 5 40* 36 7 961' 5-g-" lOOt Average Composition of High Gypsum Zone 35A-35F 48i 956'3"-960 , 3i" 79^ 11 9g- * - Argillaceous; t - Dolomite. CORE CI 41 Madison Coal Co., Boring 6 SE cor. SW5- SW5- sec. 26, T. 4 N., R. 8 W., Madison Co. Estimated composition (%) Sample Thickness Bottom depth (in.) (ft.) 710' 9" 712' 4" 713" 6" 714' 0" 714' 3" 714'H" 716' 9" 717'11" 718' 6" 719' 2" 722' 0" 722' 7" 723* 4" 723' 5" 723 '11" 724 ' 4" 725' 6" 725' 10" 728' 4" 730' 3" * = Argillaceous. Average Composition of High Gypsum Zones 26 9 27A 19 27B 14 27C 6 27D 3 27E 8 27F 22 27G 14 27H 7 271 8 28A 34 28B 7 28C 9 28D 1 28E 6 28F 5 28G 14 29 4 30 30 31 23 Gypsum Anhydrite Limestone 100* 100 Trace 70 30 Trace 25 73 2 10 5 85 10 85 5 60 10 30* 15 10 75* 10 90 5 50 45 55 5 40* 85 10 5 95 2 3 10 90* 100 90 Trace 10 100 40 60 20 80 2 98 27A-27F 72 710'9"-716 , 9" 62 25 13 28A 34 719 , 2"-722*0" 55 5 40 28B-28G 42 722'0"-725 , 6" 93 2 5 GYPSUM AND ANHYDRITE IN ILLINOIS 19 CORE CI 55 Madison Coal Co., Boring 17 NWi NWi NWi sec. 7, T. 7 N„ R. 5 W. , Montgomery Co. Estimated composition (%) Sample Thickness (in.) Bottom depth (ft.) Gypsum Anhydrite Limestone 44A 16 991 ' 8" 10 90* 44B 8 992 • 4" 100* 45A 8 993' 0" 60 40* 45B 13 994' 1" 95 5 Trace 45C 14 995' 3" 60 35 5 45D 4 995' 7" 15 Trace 85 45E 1 996' 2" 90 Trace 10 45F 4 996' 6" 5 95 45G 7 997 i 1 « 20 5 75 45H 12 998' 1" 60 35 5 451 4 998' 5" 60 15 25* 45J 12 9991 5 » 45 50 5 45K 2 999 • 7" 10 90* 45L 4i 999' lli" 60 25 15 Average Composition of Hi .gh Gypsum Zones 45A-45C 35 992'4"-995 , 3" 73 16 11 45H-45L 34i 997 , l"-999 , lli" 52 35 13 * =: Argillaceous. CORE C2663 Superior Oil Co., Singer No, 1 SEi SEi Nltf£ sec. 3, T. 8 N., R. 2 III., Montgomery Co. Estimated composition {%) Thickness Bottom de pth Gypsum Anhydrite Dolomite Limestone (ft.) (ft.) 2 1446 100 3 1449 2 98 4 1453 10 90 3 1456 5 95 4 1460 2 98 1 1461 2 98 1 1462 35 65 3 1465 3 85 12 9 1474 10 20 ILLINOIS STATE GEOLOGICAL SURVEY Cen. CORE C28 Millar Co., Sample Farm sec. 11, T. 15 N., R. 3 W. , Sangamon Co. Estimated composition {%) Thickness Bottom depth Gypsum Anhydrite Dolomite Other (ft.) (ft.) 2 892 Ls.' -100 2 894 10 - Ls. & dol. -90 1 895 97 3 1 896 5 95 2 898 100 Trace 1 899 50 50 4 903 10 90 2 905 40 50 10 4 909 10 90 3 912 15 85 3 915 15 85 3 918 20 80 4 922 85 10 Ls. & sh. 5 1 923 75 5 20 1 924 10 5 85 5 929 50 50* 3 932 10 90* 20 952 100 2 954 45 50 5 2 956 10 85 5 3 959 5 95 3 962 40 50 10 44 1006 Dol . & ls.-lOO 1 1007 25 50 - Dol . & sh.-25 3 1010 10 90 2 1012 15 80 5 3 1015 15 70 15 2 1017 100 7 1024 5 90 5 1 1025 100 2 1027 50 50 2 1029 10 90 2 1031 5 15 - Dol . & sh.-80 2 1033 5 95 9 1042 15 - Dol . & ls.-85 1 1043 95 5 1 1044 5 95 3 1047 Trace 85 15 2 1049 5 95 4 1053 50 40 10 2 1055 2 98 Average Composition of High Gyp: sum Zones 4 894-898 75i 24i 5 918-923 83 9 4 4 * - Silty and argillaceous; Ls. - Limestone; Dol. - Dolomite; Sh. - Shale, GYPSUM AND ANHYDRITE IN ILLINOIS 21 CORE 2740 Superior Oil Co., H. C. Ford Farm, No. CI 7 SW5- SEi sec. 27, T. 4 S., R. 14 W., White Co. Estimated composition (%) Thickness (ft.) Bottom depth (ft.) Gypsum Anhydrite Dolomite 1 5 1 9 3144 3149 3150 3159 Trace 100 50 100 - silty 50 - silty 100 2 3 1 3161 3164 3165 50 100 50 - silty 100 PART 2 Studies of samples from cable tool and rotary wells in Bond, Clark, Ma- coupin, Madison, Montgomery, and Sangamon counties. Only those wells are reported in which at least one of the samples contained 25 percent or more gypsum. One well with only one sample containing 20 percent gypsum is in- cluded because there was no anhydrite associated with the gypsum. Trace =less than 1/2%. Little = more than 1/2% but less than 1%. WELL 3522 NWi NWi sec. 16, T. 6 N., R. 3 W., Bond Co. Estimated composition (%) 1230 2 - 98 1235 25 35 40 1240 Little Little 100 1285 Trace Trace 100 1295 Little Trace 100 Thickness represented Bottom depth Gypsum Anhydrite Limestone Dolomite by samples (ft.) (ft.) 5 5 5 45 10 WELL 7126 NWi NWi SE5- sec. 8, T. 6 N., R. 4 W., Bond Co. Estimated composition (%) Thickness represented Bottom depth Gypsum Anhydrite Limestone Dolomite by samples (ft.) (ft.) 5 1145 3 - 97 5 1150 5 - 95 5 1155 15 - 85 22 ILLINOIS STATE GEOLOGICAL SURVEY WELL 7126 (continued) Estimated composition (%) Thickness represented Bottom depth Gypsum Anhydrite Limestone Dolomite by samples (ft.) (ft.) 5 1160 30 - 70 10 1170 5 - 95 5 1175 8 - 92 5 1180 5 95 10 1190 45 - 55 5 1195 12 - 88 WELL 3843 NWi SWi SEi sec. 27, T. 7 N., R. 4 W., Bond Co. Estimated composition {%) Thickness represented Bottom depth Gypsum Anhydrite Limestone Dolomite by samples (ft.) (ft.) 10 1090 50 - 50 5 1095 17 - 83 6 1101 20 - 80 9 1110 8 - 92 5 1115 4 - 96 15 1130 2 - 98 5 1135 5 - 95 5 1140 10 - 90 7 1147 15 - 85 - WELL 7783 NWi SWi NEi sec. 31 , T. 7 N. , R. 4 W., Bond Co. Estimated composition Thickness represented Bottom depth Gypsum Anhydrite Limestone Dolomite by samples (ft.) (ft.) 30 1030 Little - 100 10 1040 25 - 75 10 1050 Little - 100 WELL 19,249 SWj SEi NWi sec. 26, T. 7 N., R. 6 W. , Macoupin Co. Estimated composition {%) Thickness represented Bottom depth Gypsum Anhydrite Limestone Dolomite by samples (ft.) (ft.) 30 930 2 - 98 10 940 10 - 90 GYPSUM AND ANHYDRITE IN ILLINOIS 23 WEIL 19,249 (continued) Estimated composition (%) Thickness represented Bottom depth Gypsum Anhydrite Limestone Dolomite by samples (ft.) (ft.) 10 10 10 10 20 950 15 960 Little 970 20 980 10 000 Little 85* 80 90 100 100* * Includes shale. WELL 3480 SWi SEi SEi sec. 2, I. 3 N„ R, 9 W„ Madison Co. Estimated composition {%) Thickness represented Bottom depth Gypsum Anhydrite Limestone Dolomite by samples (ft.) (ft.) 10 25 10 5 5 15 5 515 Little 525 3 550 - 560 35 565 10 570 20 585 25 590 3 Little 100 97 100 65 80 75 97 90 WELL 3162 SEi SWi NEi sec. 9, T. 4 N., R. 8 W., Madison Co. Estimated composition {%) Thickness represented Bottom depth Gypsum Anhydrite Limestone Dolomite by samples (ft.) (ft.) 10 10 10 35 10 25 20 15 10 10 10 15 650 5 - 95 660 25 - 75 670 3 - 97 705 Little - 100 715 25 - 75 740 5 - 95 760 Little - 100 775 50 Little 50 785 40 Little 60 795 5 Little 95 805 15 Little 85 820 10 Little 90 24 ILLINOIS STATE GEOLOGICAL SURVEY WELL 1312 SWi SWi NEi sec. 24, T. 5 N., R. 8 W. , Madison Co. Estimated composition {%) Thickness represented Bottom depth Gypsum Anhydrite Limestone Dolomite by samples (ft.) (ft.) 10 740 20 - 80 10 750 3 - 97 7 757 5 - 95 11 768 30 - 70 7 775 5 - 95 - 20 795 Little - 100 WELL 6129 SE? SWi NEi sec. 27, T. 5 N., R. 8 W., Madison Co. Estimated composition {%) Thickness repi 'esented Bott .om depth Gyp si by samples (ft.) (ft.) 5 695 10 5 700 20 10 710 85 5 715 15 Gypsum Anhydrite Limestone Dolomite 90 80 15* 85 * - Cherty. WELL 18,946 SEi SEi SWi sec. 29, T. 6 N., R. 8 W., Madison Co. Estimated composition {%) Thickness represented Bottom depth Gypsum Anhydrite Limestone Dolomite by samples (ft.) (ft.) 15 625 5 - 95 10 635 Trace - - 100 15 650 40 60* * Includes shale. WELL 5311 NWi SEi NWi sec. 10, T. 9 N., R. 2 W., Montgomery Co. Estimated composition {%) Thickness repi esented Bottom depth Gypsi by samples (ft.) (ft.) 5 1505 10 10 1515 20 5 1520 30 10 1530 - 5 1535 20 5 1540 10 Gypsum Anhydrite Limestone Dolomite 15 75 10 70 10 60 100 10 - 70 5 85 GYPSUM AND ANHYDRITE IN ILLINOIS 25 WELL 5232 SWi SWi SE5- sec. 28, T. 10 N., R. 3 W., Montgomery Co. Estimated composition {%) Thickness represented I by samples (ft.) 15 15 10 5 5 5 5 5 5 5 5 5 5 5 5 om depth Gypsum Anhydrite Limestone Dolomite (ft.) 1165 - 100 - - 1180 55 10 - 35 1230 10 20 70 1235 15 70 15 1240 10 20 - 70 1245 10 30 - 60 1250 20 15 - 65 1285 15 55 - 30 1290 10 20 - 70 1295 - - - 100 1300 - 20 80 - 1305 - 10 90 - 1310 - 30 70 - 1315 - 70 30 - 1320 - 10 90 - WELL 4832 NWi NE£ SE5- sec. 31, T. 11 N., R. 5 W., Montgomery Co. Est imated composition (%) Thickness represented Bottom depth by samples (ft.) (ft.) 5 5 5 5 5 5 10 10 5 5 10 5 10 5 10 980 985 990 995 1000 1005 1015 1025 1030 1035 1045 1050 1060 1065 1075 Gypsum Anhydrite Limestone Dolomite _ _ 100 _ 60 5 35 - 10 3 87 - 100 - 30 Little 70 - 3 97 - Trace 100 - 25 4 71 - 20 50 30 - 8 4 88 - 2 7 91 - Little 10 90 - Little 2 98 - 25 35 40 - 2 5 93 - 26 ILLINOIS STATE GEOLOGICAL SURVEY WELL 19,477 SWi NWi NE? sec. 10, T. 15 N., R. 3 11., Sangamon Co. Estimated composition {%) Thickness represented Bottom depth Gypsum Anhydrite Limestone Dolomite by samples (ft.) (ft.) 11 866 5 - 95 19 885 1 1 98 5 890 20 70 10 6 896 60 35 5 7 903 70 20 10 5 908 15 - 85 4 912 10 - 90 18 930 - - 100 5 935 5 15 80 47 982 - - 100 8 990 35 60 5 5 995 5 35 60 5 1000 5 10 85 5 1005 2 8 90 10 1015 - - 100 9 1024 20 25 55 Illinois State Geological Survey Circular 226 26 p., 7 figs., appendix immzij} CIRCULAR 226 ILLINOIS STATE GEOLOGICAL SURVEY URBANA * Jttuw.r *. .«uno*««5i>pu 114 ▼ ■"■■■- ▼