s 
 
 14.GS: 
 CIR386 
 
 c. 2 
 
 SURVEY. UBRARY 
 
 FILE COPY 
 Earth Materials 
 STATE OF ILLINOIS Technology Section 
 
 DEPARTMENT OF REGISTRATION AND EDUCATION 
 
 THE BORDEN SILTSTONE 
 
 (MISSISSIPPIAN) DELTA 
 
 IN SOUTHWESTERN ILLINOIS 
 
 David H. Swann 
 
 Jerry A. Lineback 
 
 Eugene Frund 
 
 ILLINOIS STATE GEOLOGICAL SURVEY 
 John C. Frye, Chief URBANA 
 
 CIRCULAR 386 1965 
 
Digitized by the Internet Archive 
 
 in 2012 with funding from 
 
 University of Illinois Urbana-Champaign 
 
 http://archive.org/details/bordensiltstonem386swan 
 
THE BORDEN SILTSTONE (MISSISSIPPIAN) DELTA 
 IN SOUTHWESTERN ILLINOIS 
 
 David H. Swann, Jerry A. Lineback, and Eugene Frund 
 
 ABSTRACT 
 
 The lower Valmeyeran Borden Siltstone in Illi- 
 nois has the internal structure of a delta, with top- 
 set, foreset, and bottomset beds. Foreset slopes 
 extend several miles and dip 30 to 90 feet per mile. 
 The delta front progressed southwestward across 
 southern Illinois in water 500 to 700 feet deep and 
 filled a basin lying on the southeast side of a cri- 
 noidal-carbonate bank that is the Burlington-Keokuk 
 Limestone. Borden sediment was carried by the 
 Michigan River from the Canadian Shield region. 
 
 INTRODUCTION 
 
 A tongue-shaped subsurface body of the Borden Siltstone of early Valmey- 
 eran (Middle Mississippian) age, 400 to 700 feet thick, extends southwestward 
 across central and southern Illinois (fig. 1). Closely spaced rotary drilling near 
 the western end of the tongue permits well to well tracing of many stratigraphic 
 horizons within the Borden by means of electric logs. Nine selected horizons, 
 designated A through I, have been mapped in an area comprising all of Clinton 
 County and parts of St. Clair, Washington, Jefferson, Marion, Fayette, Bond, 
 and Madison Counties. These horizons do not parallel the base and top of the 
 formation, but slope from near the top to near the base in a general southwesterly 
 direction. They demonstrate that the internal structure of the Borden Siltstone is 
 that of a delta, with topset, foreset, and bottomset beds (fig. 2). 
 
 The Borden Siltstone is part of an extensive body of Kinderhookian and 
 Valmeyeran clastic rocks extending eastward from Illinois into Indiana, Michigan, 
 Kentucky, Ohio, Pennsylvania, West Virginia, and New York. These elastics 
 were carried westward or southwestward into deep water by rivers that had their 
 sources in the northern Appalachians and in the Canadian Shield. 
 
ILLINOIS STATE GEOLOGICAL SURVEY CIRCULAR 386 
 
 Figure 1 - Areal extent of the Borden Siltstone in Illinois. 
 
BORDEN SILTSTONE ( M I S S I S S I P PIA N ) DELTA 
 
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ILLINOIS STATE GEOLOGICAL SURVEY CIRCULAR 386 
 
 The Borden is exposed in central and southern Indiana and in Kentucky. 
 It consists of siltstone and shale with some fine sandstone and crinoidal limestone. 
 In Indiana the Borden is divided into a basal shale (New Providence) and a thicker 
 upper siltstone that contains some cross-bedded channel deposits of fine-grained 
 sandstone. Most of the Borden is sparsely fossiliferous, but in a few places 
 fossils are abundant. Small crinoidal limestone bioherms occur. 
 
 The Borden generally rests on the Kinderhookian Chouteau Limestone, called 
 Rockford in Indiana, but in small areas it overlaps onto the New Albany Shale and 
 Silurian rocks. It is overlain by the Harrodsburg Limestone or by the Salem Lime- 
 stone. 
 
 The Borden Siltstone extends westward to within a few miles of outcrops of 
 the dominantly limestone, early Valmeyeran sequence near St. Louis. The siltstone 
 is replaced within two miles by a sequence consisting of a basal red and green 
 shaly limestone (Fern Glen) overlain by light-colored limestone (Burlington-Keokuk) 
 overlain by shale with interbedded limestone (Warsaw) . Southeast of the siltstone 
 tongue, lower Valmeyeran rocks consist of dark-colored silty siliceous limestone 
 (Fort Payne) resting on a relatively thin Springville (New Providence) Shale. 
 
 This report incorporates results from an unpublished thesis by Eugene Frund 
 (1953), now geologist with Humble Oil and Refining Company, and work reported 
 by D. H. Swann, Eugene Frund, and D. B. Saxby (1953). 
 
 INTERNAL STRUCTURE OF THE DELTA 
 
 The Borden Siltstone delta in Illinois is unique among described Paleozoic 
 deltas because electric logs from closely spaced wells in several oil pools show 
 that the siltstone has numerous traceable topset, foreset, and bottomset bedding 
 planes. Classic internal delta structure has not been reported from other Missis- 
 sippian deltas such as the Bedford delta of Ohio (Pepper, de Witt, and Demarest, 
 1954). Paleozoic deltas previously have been recognized by morphology, facies, 
 and stratigraphic relations. 
 
 The Borden in Clinton County is essentially gray, calcareous or dolomitic 
 siltstone that seems uniform from top to bottom except for a downward decrease in 
 average grain size and a corresponding increase in clay content. However, subtle 
 changes in grain size and clay and carbonate content produce irregularities in the 
 resistivity and potential curves (fig. 2). 
 
 If wells several miles apart are compared, the slight variations in the 
 electric log curves bear little resemblance to each other. However, where wells 
 are closely spaced, dozens of these minor markers can be traced from well to well. 
 
 At numerous places, dip computations based on closely spaced wells show 
 that the markers dip south, southwest, or west as much as 30 to 90 feet per mile 
 with respect to horizons in overlying and underlying formations. 
 
 Nine electric log marker horizons, designated A through I (fig. 2), were 
 selected for mapping. The character of each marker changes somewhat as it is 
 traced for several miles. The markers are more distinctive and have higher relief 
 in the middle and upper parts of the Borden. They fade to indistinct wiggles when 
 traced down to the south or west into the shaly sections near the base of the Borden. 
 
 The Borden sediments were somewhat thicker and had correspondingly 
 steeper slopes before post-depositional compaction. The foreset slope of the 
 
BORDEN SILTSTONE ( M I S S IS S I P PIA N) DELTA 
 
 MILES 
 Q 2 4 6 8 10 
 
 Figure 3 - Advance of the delta as shown by successive positions of the line 
 where the Borden reached a cumulative thickness of 300 feet, taken 
 from figures 5-12 . 
 
 delta advanced from northeast to southwest in Clinton County (fig. 3). Areas of 
 greatest accumulation migrated in response to shifts in active distributaries. 
 
 Horizon A represents the sea floor before the deltaic advance recorded here. 
 The floor was relatively level over most of the map area, but in the northwest it 
 rose to a high underlain by 200 feet of earlier Borden deposits. The Borden sedi- 
 ments below horizon A (fig. 4) probably include the toe of an earlier deltaic advance 
 as well as the bottomset beds of the earliest stages of the advance described here. 
 
 The map of unit A-B (fig. 5) shows the first appearance of the main delta 
 in the map area. Succeeding maps of units B-C through E-F record a southward 
 extension of a major distributary, as shown by the shift of areas of maximum dep- 
 osition (figs. 6-9). During deposition of unit E-F, the southward migrating dis- 
 tributary in eastern Clinton and western Marion Counties became overextended and 
 
ILLINOIS STATE GEOLOGICAL SURVEY CIRCULAR 386 
 
 MILES 
 3 4 6 
 
 Thickness of unit, interval 20 feet; 10 feet thickness shown by dashed line 
 
 Figure 4 - Thickness of Borden sediment below horizon A. 
 
 ceased to be the major outlet in this area. Sediment was deposited by new dis- 
 tributaries farther west (T . 4 N., R. 3 W.) (fig. 9). Units F-G, G-H, and H-I 
 show a westward growth of the delta front (figs . 10-12) . At the time of horizon I 
 there was still a narrow trough 400 feet deep in the western part of the area. The 
 trough was filled by younger siltstone beds before the end of Borden deposition. 
 
 The delta continued to grow to the southwest and succeeding sediments 
 were carried across Clinton County. At the end of Borden deposition, the top of 
 the formation was a relatively horizontal surface. Thin beds of fossiliferous lime- 
 stone in the upper part of the Borden indicate shallow water conditions . The 
 Borden thins from east to west (fig. 12); this reflects less subsidence near the 
 positive area of the Ozarks . The Borden also thins slightly over Silurian reefs, 
 due to preferential compaction of the Silurian and Devonian non-reef sections 
 during Borden time (fig. 13). 
 
BORDEN SILTSTONE ( M I S S I S S I P PIA N ) DELTA 
 
 R 6 W 5 
 
 _ . Thickness of unit, interval 20 feet 
 
 — — Cumulative thickness, intervol 100 feet 
 Note Entra intervals dashed 
 
 Figure 5 - Thickness of unit A-B and cumulative thickness from base of the 
 Borden to horizon B. 
 
 Cumulative thickness maps of an advancing delta (figs. 5-12) are in 
 essence submarine topographic maps. The difference in elevation between the 
 top of the delta and its base is a measure of water depth. Compaction of the 
 deltaic sediments has shortened the section by an unknown factor, perhaps 20 
 or 30 percent, and the water depth must be increased correspondingly. The cumu- 
 lative thickness maps indicate that the water was 500 to 700 feet deep in front of 
 the delta in eastern Clinton County. 
 
 Individual distributary channels were not traced in this study, but their 
 existence may be inferred from the presence of cross-bedded sandstones in the 
 Indiana outcrops. Limestone beds and bioherms in the Borden attest to favorable 
 conditions for carbonate-producing organisms such as crinoids in submerged parts 
 of the delta away from active distributaries. 
 
ILLINOIS STATE GEOLOGICAL SURVEY CIRCULAR 386 
 
 The pre-compactional dips of the foreset beds in the Borden ranged from 
 0.4 degrees to a little over one degree, which is comparable to the dip of the 
 foreset slope of the modern Mississippi River delta. 
 
 STRATIGRAPHIC RELATIONS OF THE DELTA 
 
 The tongue of Borden Siltstone in Illinois (fig. 1) is flanked on the north- 
 west by the early Valmeyeran Fern Glen Limestone, Burlington-Keokuk Limestone, 
 
 . Thickness of unit, interval 20 feet 
 
 — - Cumulative thickness, interval 100 feet 
 Note Extra intervals dashed 
 
 Figure 6 - Thickness of unit B-C and cumulative thickness from base of the 
 Borden to horizon C. 
 
BORDEN SILTSTONE ( M I S S I S S I P PI A N ) DELTA 
 
 and Warsaw Shale. The transition is abrupt and is generally completed in a belt 
 no more than two miles wide that lies just northwest of the map area. Horizon A 
 rises northwestward toward a point slightly above the base of the Warsaw (fig. 14) 
 Its exact position cannot be traced to the edge of the siltstone body, but it is 
 bracketed between other markers that can be traced farther west. Red and green 
 shaly limestone and shale (Fern Glen), about 30 feet thick, can be traced directly 
 into the lower part of the thick siltstone beneath horizon A along the western edge 
 of the Borden tongue. Overlying the Fern Glen in the area of the cross section 
 
 , Thickness of unit, mtervol 20 feet 
 
 — - Cumulative thickness, interval 100 feet 
 Nole : Extra intervals dashed 
 
 Figure 7 - Thickness of unit C-D and cumulative thickness from base of the 
 Borden to horizon D. 
 
10 
 
 ILLINOIS STATE GEOLOGICAL SURVEY CIRCULAR 386 
 
 (fig. 14) is a silty limestone unit about 50 feet thick at the base of the Burlington- 
 Keokuk that can also be traced directly into the siltstone beneath horizon A. 
 
 Wells in Madison County and nearby areas are too widely spaced to show 
 details of the change, but the Assumption Consolidated oil field in Christian 
 County (fig. 1), 50 miles north of Clinton County, lies across the zone of change. 
 Electric logs from wells less than 1000 feet apart in the Assumption Consolidated 
 field show that the Burlington-Keokuk thins rapidly and underlies all but the lower 
 100 feet or less of the Borden Siltstone (fig. 15). The section from the Chouteau 
 
 , Thickness of unit, interval 20 feet 
 
 — -. Cumulative thickness, interval 100 feet 
 Note : Extro intervals dashed 
 
 Figure 8 - Thickness of unit D-E and cumulative thickness from base of the 
 Borden to horizon E. 
 
BORDEN SILTSTONE ( M I S S I S S I P PI A N) DELTA 
 
 11 
 
 to the top of the Keokuk thins southeastward from 300 feet to 100 feet in little 
 more than a mile. All parts of the Burlington-Keokuk thin, but the greatest thinning 
 occurs in the upper part. The Warsaw Shale and the Sonora Sandstone, which 
 overlie the Burlington-Keokuk, are equivalent to all but the lower 100 feet of the 
 Borden. The Burlington-Keokuk appears to have been a crinoidal carbonate bank 
 that stood topographically 200 to 300 feet above the floor of the sea into which 
 the Borden delta grew. 
 
 , Thickness of unit, inlervol 20 feet 
 
 — - Cumulative thickness, interval 100 feet 
 Note Extra intervals doshed 
 
 Figure 9 - Thickness of unit E-F and cumulative thickness from base of the 
 Borden to horizon F. 
 
12 
 
 ILLINOIS STATE GEOLOGICAL SURVEY CIRCULAR 386 
 
 In the area of detailed mapping, Borden sediments below horizon A thin 
 from north to south (fig. 4). The lower part of the unit below horizon A was 
 deposited before the full development of the crinoidal bank represented by the 
 Burlington-Keokuk Limestone. It is equivalent to the Fern Glen and the silty 
 phase locally present at the base of the Burlington (fig. 14). The middle part of 
 the section beneath horizon A appears to grade laterally into the crinoidal bank. 
 The upper part overlies the thinning edge of the crinoidal bank (figs. 14 and 15). 
 
 , Thickness of unit, intervol 20 feet 
 
 — - Cumulative thickness, interval 100 feet 
 Note : Extra intervals dashed 
 
 MILES 
 2 4 6 e 10 
 
 Figure 10 - Thickness of unit F-G and cumulative thickness from base of the 
 Borden to horizon G. 
 
BORDEN SILTSTONE ( M I S S I S S I P PI AN) DELTA 
 
 13 
 
 A thick accumulation of siltstone beneath horizon A lies along the south- 
 eastern edge of the crinoidal bank in the northwestern part of the Clinton County 
 area (fig. 4) . These deposits are part of a delta tongue, the major part of which 
 is north of the map area. The sediment may have been diverted southwestward 
 by the topographically high crinoidal bank. Another possibility is that this silt- 
 stone, and succeeding accumulations along the front of the crinoidal bank, con- 
 sists of sediment carried onto the top of the bank when the basin filled farther 
 
 , Thickness of unit, interval 20 feel 
 
 .. « Cumulative thickness, interval 100 feet 
 Note : Extra inlervols dashed 
 
 Figure 11 - Thickness of unit G-H and cumulative thickness from base of the 
 Borden to horizon H . 
 
14 
 
 ILLINOIS STATE GEOLOGICAL SURVEY CIRCULAR 386 
 
 north. Such sediment could have been transported southward by marine currents 
 and waves in the shallow water over the bank and then dumped over the edge into 
 deeper water. 
 
 SEDIMENT SOURCE AND TRANSPORTATION 
 
 In Kinderhookian and early Valmeyeran time, clastic sediments were carried 
 by rivers west and south into the Appalachian, Michigan, and Illinois Basins. 
 
 , . Thickness of unit, inlervol 20 feet 
 
 . Cumulative thickness, interval 100 feet 
 
 Note : Extra intervals dashed 
 
 2* 6 e 10 
 
 Figure 12 - Thickness of unit H-I and cumulative thickness from base of the 
 Borden to horizon I. 
 
BORDEN SILTSTONE ( M I S S I S S I P PI AN) DELTA 
 
 15 
 
 The early Mississippian Bedford delta of Ohio was built of sediments that were 
 derived from the northern Appalachians and carried southwestward by the Ontario 
 River (Pepper, de Witt, and Demarest, 1954). Mountains in eastern Pennsylvania 
 provided sediments that were transported northwestward across Pennsylvania 
 and deposited in the middle Mississippian Pocono delta (Pelletier, 1958). The 
 Borden elastics were carried southwestward across the Canadian Shield by the 
 Michigan River (Swann, 1963, 1964). The Michigan River paralleled the Ontario 
 River and repeatedly carried clastic sediments into the Illinois Basin during Mis- 
 sissippian time. The headwaters of the Michigan River may have been in rising 
 mountains in the Franklin geosyncline area of northern Canada. 
 
 . Thickness of unit, interval 20 feet 
 
 — - Cumulative thickness, interval 100 feet 
 Note' Extro intervals dashed 
 
 MILES 
 i 6 e 
 
 Figure 13 - Thickness of sediment between horizon 1 and the top of the Borden 
 with cumulative thickness of the Borden, showing thinning over 
 some Silurian reefs, e.g. in south part of I. 4 N., R. 1 E. 
 
16 
 
 ILLINOIS STATE GEOLOGICAL SURVEY CIRCULAR 386 
 
 
 
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 U> 
 
 c\jo 
 
 
 
 Figure 14 - Cross section in Clinton and Madison Counties showing relation of 
 
BORDEN SILTSTONE ( M I S S I S S I P PIAN ) DELTA 
 
 17 
 
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 5 g 
 
 5 * 
 
 to 
 
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 m 
 
 the Borden Siltstone to the lower Valmeyeran sequence of Mississippi Valley. 
 
ILLINOIS STATE GEOLOGICAL SURVEY CIRCULAR 386 
 
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 fO 
 
 V 
 
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 V 
 
 fC 
 
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 Figure 15 - Cross section in the Assumption Consolidated oil field, Christian County, 
 
BORDEN SILTSTONE ( M I S S IS S I P PIA N) DELTA 
 
 19 
 
 < 2 W 
 
 showing details of the relation of the Borden to the lower Valmeyeran sequence of Mississippi Valley. 
 
20 ILLINOIS STATE GEOLOGICAL SURVEY CIRCULAR 386 
 
 REFERENCES 
 
 Frund, Eugene, 1953, Stratigraphy of the Borden Siltstone in Clinton and adjacent 
 counties, Illinois: Univ. Illinois (Urbana) unpublished M.S. thesis, 37 p. 
 
 Pelletier, B. R., 1958, Pocono paleocurrents in Pennsylvania and Maryland: 
 Geol. Soc. America Bull., v. 69, p. 1033-1064. 
 
 Pepper, J. F., de Witt, Wallace, Jr., and Demarest, D. F., 1954, Geology of 
 the Bedford Shale and Berea Sandstone in the Appalachian Basin: U.S. 
 Geol. Survey Prof. Paper 259, 111 p. 
 
 Swann, D. H., 1963, Classification of Genevievian and Chesterian (late Missis- 
 sippian) rocks of Illinois: Illinois Geol. Survey Rept. Inv. 216, 91 p. 
 
 Swann, D. H., 1964, Late Mississippian rhythmic sediments of Mississippi 
 Valley: Am. Assoc. Petroleum Geologists Bull., v. 48, p. 637-658. 
 
 Swann D. H., Frund, Eugene, and Saxby, D. B., 1953, Osage deltaic deposits 
 in southwestern Illinois [abs.]: Geol. Soc. America Bull., v. 64, 
 p. 1480-1481. 
 
 Illinois State Geological Survey Circular 386 
 20 p., 15 figs., 1965 
 
 Printed by Authority of State of Illinois, Ch. 127, IRS, Par. 58.25. 
 
CIRCULAR 386 
 
 ILLINOIS STATE GEOLOGICAL SURVEY 
 
 URBANA