POSSIBILITY OF MISSISSIPPI /' -- VALLEY -TYPE MINERAL DEPOSITS IN INDIANA
Special Report 21 SCIENTIFIC AND TECHNICAL STAFF OF THE GEOLOGICAL SURVEY
JOHN B. PATTON, State Geologist MA URICE E. BIGGS, Assistant State Geologist MARY BETH FOX, Mineral Statistician
COAL AND INDUSTRIAL MINERALS SECTION GEOLOG Y SECTION DONALD D. CARR, Geologist and Head ROBERT H. SHAVER, Paleontologist and Head CURTIS H. AULT, Geologist and Associate Head HENRY H. GRAY, Head Stratigrapher DONALD L. EGGERT, Geologist N. K. BLEUER, Glacial Geologist GORDON S. FRASER, Geologist EDWIN J. HARTKE, Environmental Geologist DENVER HARPER, Geologist JOHN R. HILL, Glacial Geologist NANCY R. HASENMUELLER, Geologist CARL B. REXROAD, Paleontologist WALTER A. HASENMUELLER, Geologist NELSON R. SHAFFER, Geologist GEOPHYSICS SECTION PAUL IRWIN, Geological Assistant MA URICE E. BIGGS, Geophysicist and Head ROBERT F. BLAKELY, Geophysicist JOSEPH F. WHALEY, Geophysicist DRAFTING AND PHOTOGRAPHY SECTION SAMUEL L. RIDDLE, Driller WILLIAM H. MORAN, Chief Draftsman and Head THOMAS CHITWOOD, Geophysical Assistant RICHARD T. HILL, Geological Draftsman ROG ER L. PURCELL, Senior Geological Draftsman PETROLEUM SECTION GEORGE R. RINGER, Photographer G. L. CARPENTER, Geologist and Head WILBUR E. STALIONS, Artist-Draftsman ANDREW J. HREHA, Geologist BRIAN D. KEITH, Geologist EDUCATIONAL SERVICES SECTION STANLEY J. KELLER, Geologist R. DEE RARICK, Geologist and Head DAN M. SULLIVAN, Geologist JAMES T. CAZEE, Geological Assistant GEOCHEMISTRY SECTION SHERRY CAZEE, Geological Assistant R. K. LEININGER, Geochemist and Head WILLIAM E. HAMM, Geological Assistant LOUIS V. MILLER, Coal Chemist MARGARET V. GOLDE, Instrumental Analyst PUBLICATIONS SECTION JOSEPH G. HAILER, Geocnemist/Analyst GERALD S. WOODARD, Editor and Head JESSE A. HARDIN, Electronics Technician PAT GERTH, Sales and Records Cler~ Possibility of Mississippi Valley-Type Mineral Deposits in Indiana
By NELSON R. SHAFFER
DEPARTMENT OF NATURAL RESOURCES GEOLOGICAL SURVEY SPECIAL REPORT 21
PRINTED BY AUTHORITY OF THE STATE OF INDIANA BLOOMINGTON, INDIANA : .1 981 ST ATE OF INDIAN A Robert D. Orr, Governor DEPARTMENT OF NATURAL RESOURCES James M. Ridenour, Director GEOLOGICAL SURVEY John B. Patton, State Geologist
For sale by Geological Survey, Bloomington, Ind. 47405 Price $2.00 Contents Page Page Abstract ...... 1 Previously reported mineral occurrences .. 24 Introduction .. · ..1 Sample collecting and study ...... 27 Geologic setting .2 Mineral locations ...... 29 Stratigraphy .... .8 Sphalerite and galena ...... 29 Precambrian ...... 8 Fluorite and barite ...... 36 Cambrian and Cambro-Ordovician . 8 Analysis ...... 39 Ordovician · .. 9 Information from samples · ..... 40 Silurian .... · .10 Conclusions ... 44 Devonian · .10 Acknowledgments . · ..... 44 Mississippian · .22 Literature cited ...... · ..... 44 PennsyIvanian · .24 Summary .... · .24
IIIustrations Page Figure 1 Map of the midwestern United States showing areas with Mississippi Valley-type mineral deposits ...... 2 2 Diagrams illustrating recent theory of origin of Mississippi Valley-type ores (A) and possible trapping structures for oil or ore fluids (B) . 3 3 Map of Indiana showing bedrock geology ...... 4 4 Map showing structural framework and cryptoexplosion features in Indiana and nearby states ...... 5 5 Map of Indiana showing tectonic features and faults . 6 6 Rock units in which minerals have been found and generalized strati graphic column of Indiana showing major rock units mentioned in the text ...... 11 7 Maps of Indiana showing generalized contours on the Precambrian sur face inferred from geophysicaJI measurements (A) and structure con tours on the Precambrian surface and elevations of Precambrian rocks in wells (B) ...... 12-13 8 Maps of Indiana showing structure contours on top of the Knox Dolo mite (A) and thickness of the Knox Dolomite in Indiana (B) .14-15 9 Maps of Indiana showing thickness of the Black River Limestone (A); contours on top of the Trenton Limestone (B); thickness of the Trenton Limestone (C); and thickness of the dolomite facies of the Trenton Limestone (D) ...... 16 10 Map of Indiana showing thickness and outcrop of Silurian rocks . . . . 18 11 Map of Indiana showing locations of reefs 19 12 Maps of Indiana showing structure contours on top of the Muscatatuck Group (A) and thickness of the Muscatatuck Group (B) ...... 20-21 Illustrations Page Figure 13 Map of Indiana showing distribution of gypsum and anhydrite 22 14 Lithologic strip logs that allowed a rapid survey of samples 27 15 Map of Indiana showing extent of drilling and thickness of sedimentary rocks ...... 28 16 Map of Indiana showing locations and stratigraphic distribution of sphalerite and galena occurrences ...... 33 17 Examples of surface occurrences of sphalerite, fluorite, and barite . . . 34 18 Map of Indiana showing locations and stratigraphic distribution of fluorite and barite shows ...... 38
Tables Page Table 1 Generalized stratigraphy of Indiana showing approximate thickness of rock units mentioned in the text, petroleum and mineral shows, and ore potential ...... 23-24 2 Previously reported occurrences of sphalerite, barite, and fluorite in Indiana ...... 25-26 3 Sphalerite and galena occurrences in subsurface samples and surface exposures in Indiana ...... 30-32 4 Fluorite occurrences in subsurface samples and surface exposures in Indiana ...... 37 5 Distribution of subsurface shows in Indiana and sample density 39 6 Fluid-inclusion measurements on sphalerite, fluorite, barite, and quartz from Indiana ...... 41 7 Minor elements in sphalerite samples from Indiana ...... 42-43 Possibility of lVlississippi Valley-Type Mineral Deposits in Indiana ~
By NELSON R. SHAFFER
Abstract section, especially in northern Indiana where The midwestern United States is recognized as the rocks had been extensively dolomitized. a lead-zinc metallogenetic province because of In northern Indiana many minerals occur in its low-temperature Mississippi Valley-type the dolomitized reef facies of the Silurian ore deposits. These deposits are found in System and in the overlying Devonian Paleozoic dolomitic host rocks, commonly on limestones. In southern and southwestern the flanks of structurally high areas far from Indiana sphalerite and fluorite occur in the areas of igneous activity. They have simple Salem and Ste. Genevieve Limestones. Pre mineralogies, mostly sphalerite, fluorite, liminary information from fluid inclusions in galena, or barite, that are believed to have sphalerite samples indicates that some speci formed at low temperatures (700 to 200°C) mens formed at temperatures within the range from concentrated brines. One commonly reported for Mississippi Valley-type deposits. ac.:::epted ex.planation of the origin and Favorable geology, ore minerals in minor characteristics of Mississippi Valley-type amounts, and tentative evidence that ore-type deposits is that they were the natural fluids passed through suitable host rocks consequence of basin development when indicate that undiscovered Mississippi Valley sedimentary connate waters, the metal type ore deposits possibly exist in Indiana. bearing brines, migrated updip from the basin and precipitated ore minerals on encountering Introduction sources of reduced sulfur. The midwestern United States is generally Indiana lies within a structural framework recognized as a lead-zinc metallogenetic and contains many geologic features that province because of many lead-zinc ore appear suitable for the development of deposits. These deposits, collectively called Mississippi Valley-type deposits. A structural Mississippi Valley-type, have similar geologic ly high area, the Kankakee and Cincinnati characteristics and, according to many geolo Arches, crosses Indiana from northwest to gists, a similar origin in the Midwest. Deposits southeast and separates the Michigan and of this type occur in southeastern Missouri, illinois Basins. Potential-ore host rock occurs the lllinois-Kentucky fluorite district, the in the Knox Dolomite (Cambro-Ordovician); tn-state region of Oklahoma, Kansas, and the Black River and Trenton Limestones Missouri, the upper Mississippi Valley, eastern (Ordovician); the Salamonie Dolomite, the and central Tennessee (fig. 1), and foreign Louisville Limestone, and the Wabash Forma countries. tion (Silurian); the Muscatatuck Group Common features of these deposits, as (Devonian); and the Sanders and Blue River summarized by Oble (1959, 1970), Snyder Groups (Mississippian). Unconformities are at (1968), Heyl and others (1974), and many the top of the Knox, the Trenton, and the others, include: (1) occurrence in shallow Wabash. Many occurrences of sphalerite, water carbonate rocks of Paleozoic age, fluorite, barite, and galena in Indiana had mostly in dolomitized areas; (2) location on already been noted, and more than 90 new :flanks of structurally high areas, mostly far ones were found during this study. Most new from igneous or tectonically active areas; (3) occurrences were in the Black River-Trenton simple mineralogy of sphalerite, galena,
1 2 PO SSIBILITY OF MISSISSIPPI VALLEY-TYPE MINERAL DEPOSITS IN INDIANA or syngenetic pyrite (Ohle, 1977). Not all workers agree with this explanation o (for example, Ohle, 1977), but it is plausible, I and metal-rich subsurface brin es do occur o (Billings and others, 1969; Carpenter and OHI O others, 1974). This and other theories on the format ion of Mississippi Valley-type deposits have been summarized by Bastin (1939), Brown (1967, 1970), White (1968), and many others. If near-surface igneous sources are not needed to form deposits, as most workers will admit, and if brines formed in large sedimentary basins can cause mineralization, Figure 1. Map of the midwestern United States show then Indiana possibly contains Mississippi ing areas with Mississippi Valley-type mineral de Valley-ty pe ores. It lies in the lead-zinc region posits. Modified from Worl and others (1974); of the central United States, and it has a McKnight and others (1962a, 1962b); and Brobst structurally high area-the Cincinnati and (1965). Kankakee Arches-that trends diagonally across the state and separates two basins containing large volumes of Paleozoic carbon fluorite, and barite with carbonate or quartz ate rocks. Ore deposits occur along this arch gangue and traces of asphaltic material; (4) in central Kentucky and central Tennessee apparent formation in open spaces at low and along a possibly related feature in temperatures (70° to 200°C) from highly northern Illinois. Indiana's proximity to saline brines; (5) galena with anomalous lead known ore districts, the gross similarities of isotopes; and (6) highly variable sulfur isotope its geology to that of mineralized areas, and ratios. Callahan (1964) pointed out the recent theories about the origin of Mississippi association of many deposits with uncon Vall y-type ores make Indiana a favorable formiti s and suggested that unconformities area for these deposits. contribute to ore formati on, but others dispute the importance of unconformities in Geologic Setting localizing ore. Indiana occupies bout 36,290 square miles Many explanations of the observed charac of the stable craton in North America, which teristics and the origin of these deposits have according to King (1959) has undergone only been advanced. One explanation by Noble minor tectonic activity. Unconsolidated gla (1963), Jackson and Beales (1967), Beales cial materials cover the bedrock in about (1975), and many others is that Mississippi five-sixths of the state (fig. 3). Bedrock Valley-type ore deposits are formed as a consists of 3,000 0 14,000 feet of Paleozoic normal step in the evolution of sedimentary sedimentary rocks that fill t he Michigan and basins. As part of this evolution, connate illinois Basins and drape over a basement high brines in deep parts of the basin become (fig. 4) that crosses Indiana from northwest to enriched in metals and are heat ed to moderate southeast (fig. 5). The structurally high area temperatures, perhap as a byproduct of consists of two part : the Kankakee Arch, petroleum formation (Dozy, 1970; Macqueen, which is a southeasterly extension of the 1976). The warm, metal-rich brines migrate Wisconsin Arch, and the Cincinnati Arch, updip (fig. 2A) t o structurally h igher areas in which is the northwestern part of a structural a manner similar to petroleum migration. feature that ex tends southward through Ohio,
Deposits form when the brines encount er Kentucky I and Tennessee, where it is covered suitable traps (fig. 2B) and sources of reduced by rocks of t h Mississippi Embayment. The sulfur that cause precipitation of dissolved two arches join near Logansport in northwest metals as sulfides. The most likely source of ern Indiana along a structurally low feature sulfur is H2 S-rich natural gas, but other that is marked on its northwest side by the sources could be oil shales, petroleum, coal, Royal Center Fault (fig. 5). GEOLOGIC SETTING 3
A
Anticline
B
Fault
Pinchout Unconformity
EXPLANA TION
Shale, characteristically Limestone, mayor may not Impermeable ~ be porous and permeable Sandstone, commonly fI=7=Zl Dolomite, commonly porous and permeable tL=z:j. porous and permeable Figure 2. Diagrams illustrating recent theory of origin of Mississippi Valley·type ores (A) and possible trapping structures for oil or ore fluids (from Carpenter and others, 1975) (B). 4 POSSIBILITY OF MISSISSIPPI V ALLEY·TYPE MINERAL DEPOSITS IN INDIANA
EXPLANATI ON
MeL••nsboro Group
Carbondale Group Sh81e sands ron.. IIm.~(o",. thick CHis 8 Raccoon Creek Graup lSa ndston•. ,hal. clay IlmtJSl'Offl& ,hm coals
West Baden, Stephensport, and Buffalo Wallow Grou ps Shale s.f'ldst{)M Iim S$fOfM
Blue River Group UmlSrona. doloml~ -1 I Sanders Group I LimutOfl.
I Borden GJ()UP and Rocklord LrmestOl1O ~
Coldwow Shale l Gr.y s htl~ EJ Ellsworth and Sunbury Shales Gr.y tJfBBI1. • nd b1Kk Jhll~
Ne... Albany Shale Blsck shaJ. G Antrllll ShAle z .,~ 811J{;k sh.1o ~ ~ G Muscatat uCk Group LlmeSfoffll, dolomite r :; I 0 SdUflon rocks ~l Llmurone. doJ()Infr' ~tltstun.. ,fit6l, z ( ~ J G Maquoketa Gr oup i l Sh.l. l,meslf)l1(J j G Uppermost C.mb".n .nd Lowel and Middle Ordovician rock. l DO/om", hmastDM I8nds~ Figure 3. Map of Indiana showing bedrock geology. Areas north of the incUcated glacial boundaries are covered with drift. GEOLOGIC SETTING 5
EXPLANATI ON + Cryptoexplosion fea ture
_-.------ - 5,000--::" Contours on preca mbrian surface Contour mterval 1000 ft. Da tum is mean sea level.
I ( I I I Major fault Hachures on down thrown side
o 200 Miles I i o 300 Km
Figure 4. Map showing structural framework and cryptoexplosion features in Indiana and nearby states. Modified from Bond and others (1971).
Ore deposits occur along the Cincinnati flat area of about 10,000 square miles. Arch in Kentucky and Tennessee and along Sedimentary rocks dip from the ill-defined the Wisconsin Arch in the upper Mississippi crest of the arch into the basins at only 25 to Valley district. The arches are not anticlines 60 feet per mile, but dips steepen toward the that resulted from uplift but are areas that center of the basins. Older rocks crop out remained relatively stable as surrounding along the arch area, and younger rocks are basins subsided. They form a broad, relatively exposed in the basin areas (fig. 3). 6 POSSIBILITY OF MISSISSIPPI V ALLEY-TYPE MINERAL DEPOSITS IN INDIANA
o
z
-l
'"'"'" Fault Hachures on down thrown side
o 40 Miles I ill ! II !
'( 25 0 50 Km K E N u c 1 1 II 1 'I
Figure 5. Map of Indiana showing tectonic features and faults. Modified from Blakely and Varma (1976). GEOLOGIC SETTING 7 The lllinois Basin underlies about 20,000 side is down (Melhorn and Smith, 1959). square miles of Indiana and cont ains an Struct ures associated with this fault have estimated 108,000 cubic miles of rock (Bond produced gas. The Mt. Carmel Fault and and others, 1971). It is roughly spoon shaped, small r faults in Floyd (Harris, 1948) and the deepest point lying about 14,000 feet Perry (Hughs, 1951 ) Counties appear at the below the surface in southeastern Illinois. The surface. The Fortville Fault trends northeast large structures in the lllinois part of the southwestward through parts of Madison and lllinois Basin and of interest to this study are: Marion Counties and has displacements of the north-southward-trending LaSalle Anti about 100 feet. A similar fault, the Royal cline in the eastern part; mafic igneous dikes Center, is in Cass, Marshall, and Kosciusko in the southeastern part; and the Rough Creek Counties. The latter two faults, whose traces Fault System in the southern part. The latter at the bedrock surface are covered by glacial is a major fault system that has maximum drift and were found by drilling, cut across displacements of more than 2,000 feet. It and the Cincinnati Arch. Some faults are known a northeast-southwestward-trending fault to occur in but not above the Trenton system that extends into the Wabash River Limestone (Rooney, 1966), and a small but valley are closely connected with mineraliza complexly faulted area occurs near Kentland tion in southeastern lllinois. The Rough Creek in northwestern Indiana. This area, known as Fault System can be tied in with other a cryptoexplosion feature, has been studied structural features across much of the eastern by Gutschick (1976) and Tudor (1971). It is United States to form the 38th parallel 4 miles across, and the central part of this lineament of Heyl (1972). Parts of t his system circular disturbed area contains rocks that and faults in the Wabash River valley affect have been uplifted more than 1,500 feet. It southern Indiana. (See figs. 3 and 4.) resembles such structures as those at Serpent The Michigan Basin is roughly circular and Mound, Ohio, Flynn Creek, Tennessee, and contains about 108,000 cubic miles of Rose Do me, Kansas. sedimentary rocks; an estimated 47 percent Sedimentologic evidence from facies are carbonate rocks, 23 percent sandstone, 18 changes in the Trenton, noted by Rooney percent shales, and 12 percent evaporites (1966), seismic evidence by Woollard (1958), (Combs, 1971). Precambrian basement rock is and interpretation of geophysical measure estimated to lie 14,000 to 15,000 feet ments by Henderson and Zeitz (1958) suggest beneath the surface at the deepest point, that a hinge line runs across southern Indiana which seems to have changed position and connects the faulted and mineralized area through time but is presently near the center in southeastern Illinois and the St. Lawrence of Michigan (Ells, 1971). The basin contains River valley disturbances. According to northwestward-trending anticlines, some of Rooney, this hinge may someway be COD which are faulted, structures related to buried nected with the Precambrian Grenville bound reefs, and structures related to salt flowage or ary postulated by Rudman and others (1965) solution. Oil is produced in the basin, and to occur east of this general region. Possible ascending fluids that caused dolomization are hinge areas may also be marked by reef banks evident (Cohee, 1948). Shawe (1976 ) sug around the Michigan and Illinois Basins. gested that heated ascending fluids caused Structurally, Indiana appears suited to host solution of limestone, dolomitization, and ore. It contains a major positive area formation of minor sulfides in the Albion (Cincinnati and Kankakee Arches). Deep Scipio Trend of Michigan. In Indiana the basins on either side of the arches contain Michigan Basin is fringed by a large reef bank thick sequences of potential source rocks that (fig. 11). have been buried deeply enough to produce Major faults in Indiana are the Mt. Carmel, oil or gas and probably also warm mineral Fortville, and Royal Center Fault. The Mt. izing fluids. Faults occur that ould transmit Carmel in south-central Indiana has been heated fluid upward, even from the Precam traced 55 miles. It is a normal fault and has a brian basement. Potential-ore traps are af displacement of 80 to 175 feet, and its west forded by these and major unconformities. 8 POSSmILITY OF MISSISSIPPI VALLEY-TYPE MINERAL DEPOSITS IN INDIANA Stratigraphy based on geophysics and information from a Potential-ore host rocks occur throughout the few wells, must be very general (fig. 7), but stratigraphic section. General information they are valuable because ore tends to occur conco3rning the extent, thickness, lithology, around high areas. Because of poor well and features pertinent to their potential role control, only the broad general form of the as source or host rocks is summarized below Cincinnati Arch and the basins can be clearly for some rock units in Indiana. proved, but geophysical evidence (Henderson The Paleozoic rocks in Indiana (fig. 6) and Zeitz, 1958) suggests several distinct consist mainly of shallow-water carbonate topographic highs on the basement surface. rocks, sandstones, shales, evaporites, and coal. But recent work by Rudman and others The carbonate rocks are of main concern for (1972) explains that geophysical anomalies this study because most Mississippi Valley ore are due to intrusives or flows of dense deposits are hosted by dolomite or limestone. magnetically susceptible materials into lighter Organic-rich black shales, such as are found in acidic rocks rather than to relief on the the New Albany Shale, or coals of Pennsyl Precambrian surface. Basement scarps have vanian age have some potential for mineraliza been observed beneath structures in the tion and should not be overlooked, but sedimentary section, and the basic form of carbonate rocks are the mostly likely host the Precambrian surface is assumed to be rocks. Precambrian basement rocks generally reflected by overlying sediments (Bond and lie too deep below the surface to be others, 1971). Relief on the unconformity at considered as reasonable exploration targets, the Precambrian surface should be expected. but highs on the Precambrian surface may And although a figure of 1,600 feet of relief help channel ore fluids or localize ore. over about 45 miles in Ohio (Green, 1957) is suspect, well data indicate nearly 700 feet of PRECAMBRIAN relief in western lllinois (Bond and others, The Paleozoic sedimentary section rests 1971). unconformably on Precambrian basement rocks. Only about 20 wells have penetrated CAMBRIAN AND CAMBRO-ORDOVICIAN this basement, so only broad generalities are The first sedimentary unit that overlies the known about it. Kottlowski and Patton Precambrian crystalline rocks in Indiana is the (1953) and Greenberg and Vitaliano (1962) Mount Simon Sandstone. It is medium- to have described Precambrian rocks of Indiana coarse-grained poorly consolidated sandstone petrologically, and Rudman and others that ranges in thickness from 500 feet in (1965) have summarized the general distribu southeastern Indiana to more than 2,000 feet tion of rock types. Bradbury and Atherton in the northwest; the lower 300 to 400 feet of (1965) have described Precambrian rocks in this unit is reddish because of high feldspar illinois, and Botoman (1975) and Owens content. It is correlative with the Lamotte (1967) have described those in Ohio. Rudman Sandstone of Missouri and is called the Mount and others (1965, 1972) have summarized Simon Sandstone in Dlinois, Michigan, and geophysi.cal evidence of the basement rocks in Ohio. This unit probably does not contain the Midwest and Indiana, and Lidiak and ore; but it might act as a permeable bed for others (1966) have reported isotopic ages transmitting deep fluids from the center of obtained from basement rocks of the the basin to the margin, and its feldspars Midwest. These reports indicate that the might provide a source of metals. basement consists of igneous and metasedi Above the Mount Simon lies the Eau Claire mentary rocks about 1.1 to 1.3 billion years Formation, which is mainly dolomitic sand old. Igneous lithologies range from abundant stones, shales, and silty dolomites containing granites to sparse basalt, and metamorphic abundant glauconite grains. It thins eastward lithologies consist mainly of marble and from more than 700 feet to 500 feet and metasediments. Direct evidence for pro correlates with the Franconia Formation or nounced highs on the bedrock surface that Galesville Sandstone of illinois. The Eau could help localize ore is lacking, but these Claire is a possible source for metal~bearing highs have been postulated. brines. Interpretations of the basement surface, The Knox Dolomite of Cambro-Ordovician STRATIGRAPHY 9 age conformably overlies the Eau Claire. It its base; the Joachim is a tan finely crystalline contains an estimated 27 percent of the dolomite (Gutstadt, 1958). Both formations sedimentary rocks of Indiana and is correla thin eastward and are absent in parts of tive with ore-bearing rocks elsewhere in the eastern Indiana. The maximum thickness of Mj dwest. The Knox ranges from 500 t o 1,500 the St. Peter is 135 feet, and that of the feet in thickness and is composed mainly of Joachim is about 70 feet. Although the gray, white, or tan finely crystalline dolomite, Joachim may have some ore potential, it is but in places it contains minor amounts of rather thin; the St. Peter is an unlikely host limestone and chert. A thick (400-foot) bed but could have offered avenues for fluid of clean quartz sand is contained within the movement. Knox in southeastern Indiana (Patton and Overlying the Joachim is a section of Dawson, 1969). The Knox thins northward Middle Ordovician carbonate rocks-the Black because of depositional thinning and erosional River and Trenton Limestones. The Black truncation of younger beds (fig. 8). Consider River is brown lithographic to fine-grained able erosion occurred at the top of the Knox. limestone that has some dolomite or argilla Patton and Dawson (1969) presented evi ceous units. It ranges in thickness from about dence for petroleum accumulations in butte 100 feet (fig. 9A) in the north, where it is like erosional remnants of the Knox Dolomite dolomitized, to more than 600 feet in the and pointed out excellent conditions for southwest, where it is limestone with an entrapment at the top of the Knox argillaceous section at the base. Thin benton throughout most of central and eastern itic shales in the upper part of the Black River Indiana. may represent the Pencil Cave or Mudcave Gutstadt (1958) correlated Knox rocks Bentonite of the Tyrone Limestone in with those as young as the Shakopee Kentucky. Because of its fine grain size and Dolomite or Prairie du Chien Group of Illinois low permeability, the Black River would not and the Cotter Dolomite of Missouri. He likely contain ore. But it is correlative with made no correlation with the Knox Group of the Platteville Group of northern Illinois, an Tennessee, but he considered that the ore-bearing rock, and could be a host if Shakopee was lithologically similar to the top fracturing or dissolution produced local areas of a unit in Kentucky called by Freeman of increased porosity or open spaces. (1953) the Jefferson City-Cotter formation. The Trenton Limestone (fig. 9B ) ranges He doubted that truncation was the sole cause from 0 to about 225 feet in thickness (fig. of the Knox thinning northward and stated 9C) and thins southward. It consists of tan that the upper Knox equivalents are in fine- t o medium-grained limestone, but it is northern Indiana and Michigan. extensively dolomitized (fig. 9D) in northern The Knox represents one of the best and especially northwestern Indiana. Many potential-ore hosts in Indiana because it is vugs with dolomite rhombs are present in mineralized in the Midwest; it has an erosional dolomitized areas, and pyrite is common in unconformity at its top; it overlies and even the upper parts. These rocks hosted huge has within itself permeable units; it is known deposits of oil and gas in east-central Indiana, to contain some oil; it has dolomite as the and many samples throughout northern dominant lithology; and it contains a few Indiana show oil or bituminous residues. small shows of sphalerite. It represents a Evidence for a widespread unconformity at reasonably shallow exploration target along the top of t he Trenton was given by Rooney the Cincinnati Arch and is only sparsely (1966), who mentioned examples of drilling drilled in much of Indiana. probably intersectin g caves. This suggests that extensive solution and possibly karstification ORDOVICIAN affected the Trenton. The Trenton has good Unconform ably at op the Knox lie rocks of ore-hosting potential because it is correlative the Chazyan Series that contain the St . Pet er with units that contain ore, it is known to Sandstone and t he Joachim Dolomite of the have contained fluids capable of dolomitiza Ordovician System. The St. Peter is loosely tion, and it contains oil. Solution of upper consolidated fine- to medium-grained sand parts of the Trenton probably occurred, and a stones, and soft green shale occurs spottily at relatively impermeable shale unit now overlies 10 POSSIBILITY OF MISSISSIPPI VALLEY-TYPE MINERAL DEPOSITS IN INDIANA this upper surface. The Trenton is correlative host ore because it contains permeable vuggy with the Galena Group of Wisconsin and dolomite, especially in northern Indiana, it is Illinois. bounded below by an unconformity in much The Trenton is covered by 200 to 1,000 of Indiana, and it is covered by impermeable feet of interbedded shales and limestones of shale. the Maquoketa Group (Ordovician) that is a Above the Waldron lies light-gray to brown clastic wedge of rocks whose thickest area is fme-grained argillaceous dolomite or dolo to the east. Calcareous gray or brown shales mitic limestone known as the Louisville make up most of this unit, and limestones are Limestone. This unit is mottled and contains only about 20 percent. The limestones have laminae of a black organic component. been dolomitized in northwestern Indiana. Reefs make up a significant part of the Gutstadt (1958) and Gray (1972) have Wabash Formation. As previously mentioned, described the Maquoketa in detail. This large barrierlike banks occur around the formation shows little promise for ore, but it basins. Smaller individual reefs or reef may have acted as a cap rock that impeded complexes containing several reefs dot the the flow of mineralizing solutions. state (fig. 11). Reef rocks are porous, and most of them are almost pure dolomite. They SILURIAN are assigned to the Huntington Lithofacies Silurian rocks (fig. 10) unconformably overlie and are surrounded laterally mainly by the Maquoketa and consist in ascending order fine-grained argillaceous and cherty carbonate of the thin basal (4- to 14-foot) limestone rocks of the Mississinewa Shale Member and known as the Brassfield Limestone; the thick the Liston Creek Limestone Member. Reefs (90- to 200-foot) gray fine-grained unit called are valuable sources of dolomite aggregate in the Salamonie Dolomite; the thin (10- to northern Indiana, and solution features are 30-foot) argillaceous carbonate or shale called commonly observed in places where large the Waldron Shale or Formation; 50 to 85 sections are exposed in quarries. Several iarge feet of mottled brown fine-grained to specimens of sphalerite have been found in sublithographic carbonate rocks named the these exposures. Silurian reefs have a good Louisville Limestone; 100 to more than 400 potential for being mineralized because they feet of the Huntington Lithofacies (reef are relatively porous and are surrounded by facies) and the nonreef facies of the Wabash much less porous rock, many of them are Formation; and thin (0 to 90 feet) fine composed of dolomite, many of them contain grained limestones or dolomites of the Salina dead oil, and some of them sho w solution Formation. Rocks of Silurian age are perhaps features below a major unconformity. Reefs the most extensively studied rocks in Indiana. host or are associated with Mississippi They have been studied by Pinsak and Shaver Valley-type deposits elsewhere, but Silurian (1964), Shaver (1974a, 1976), Becker (1974), rocks throughout the world rarely contain and many others. The Salamonie, the this type of deposit. Huntington Lithofacies of the Wabash, and the Salina have some ore potential. DEVONIAN The Salamonie Dolomite is made up of Overlying Silurian rocks are Lower and light-gray fine-grained porous dolomite and Middle Devonian (fig. 12) carbonate rocks. dolomitic limestone. It contains beds of vuggy Lower Devonian formations are known to dolomite and is cherty in many areas. In occur only in southwestern Indiana at depth. southern Indiana it is subdivided into the Becker (1974) noted that Lower Devonian Osgood and Laurel Mem bers. The Salamonie rocks are mainly carbonate rocks or cherty of northern Indiana correlates with the gray carbonate rocks. Where Lower Devonian and white rocks of the Niagara Group of rocks are absent, carbonate rocks of the Michigan or with the Joliet Dolomite of Muscatatuck Group unconform ably overlie lllinois. The Salamonie has some potential to Silurian rocks. STRATIGRAPHY 11
Vertical Scale M Ft 0 0 Sanders Group
50 EXPLANATION z 200 a::"" " in (/) 100 Unconsolidated materials McLeansboro (/) (/) 400 Group ::;; o Borden Group 150 Sandstone X Knox Dolomite 600 200 Limestone
X Carbondale New Albany z X Group ::'!'~=~--== Shale Shaley limestone z X Muscatatuck ~f§~§~r {j. 0 Group Shale
~ Wabash o Formation Coal ~ I 0:: Eau Claire => Louisville X Raccoon Creek Formation =" I / Limestone Group (/) Dolomite X Salamonie Dolomite ~ Sandy dolomite
Buffalo Wallow Gypsum and anhydrite Group X Maquoketa Group Stephensport Metamorphic and Group igneous rocks
Unconformity West Baden z Group U"" Mount Simon X :;: z Sandstone Sphalerite ::'!' o Limestone " X Trenton " ~ I {j. (/) lilf ~ Fluorite (/) X Blue River (/) ::;; {j. Group X Black River o i Limestone Galena o Barite
I X {j. Sanders St. Peter Sandstone o Group Knox Dolomite
Figure 6. Rock units in which minerals have been found and generalized stratigraphic column of Indiana showing major rock units mentioned in the text. Modified from Shaver and others (1970). 12 POSSIBILITY OF MISSISSIPPI VALLEY-TYPE MINERAL DEPOSITS IN INDIANA
A
EXPLANATION
___ - 2000 ------ Hypothetical basement contour Based on geophysical data. Contour interval 500 ft. Datum is mean sea level
a 50 Miles I I I a 75 Km
Figure 7. Maps of Indiana showi ng generalized contours on the Precambrian surface inferred from geophysical measure· ments (from Henderson and Zeitz, 1958) (A) and structure contours on the Precambrian surface and elevations of Precambrian rocks in wells (modified from Bond and others, 1971; Becker and others, 1978) (B). STRATIGRAPHY 13
B ----[------~--~------T----· J - 3644 1' i' // ..-- I ---- 'l ---- t --~~15 : I . ,__/' , I -----t---I -37591 (""7''''1 -3105 1 I I EXPLANATION I.-/ / ,1---.' .-3176 Well location showing elevation 1 at Precambrian surface
____ -4,OOO~ Structure contour on Precambrian surface t- I Contour interval 7000 ft. 500 ft auxi/liary contours are shown with dashed lines. I, Datum is mean sea level
~ Fault Hachures on down thrown side (from Dawson. 1971)
Figure 7 ----COntinued 14 POSSIBILITY OF MISSISSIPPI VALLEY-TYPE MINERAL DEPOSITS IN INDIANA
A
I I EXPLANATION L,; ____ - 800--I Structure contour on top I of Knox Dolomite Contour interval 200 ft. Datum is mean sea level
~ Fault Hachures on downthrown side (from Dawson. 1971)
50 Miles II I 75 Km
Figure 8_ Maps of Indiana showing structure contours on top of the Knox Dolomite (modified from Bond and others, 1971) (A) and thickness of the Knox Dolomite in Indiana (from Bond and others, 1971; Dawson, 1960; and Gu tstadt, 1958) (B). STRATIGRAPHY 15
B
EXPLANATION
____ 1000---- Isopach contour showing thickness of Knox Dolomite Contour interval 500 ft. 250 ft auxilliary contours are shown with dashed lines.
Figure 8.."..-(;ontinued 16 POSSIBILITY OF MISSISSIPPI V ALLEY-TYPE MINERAL DEPOSITS IN INDIANA
rsB ;;:;;-;~ ------l ~ / ' A y/1 \.'0'0 I B I : 1 i~ 1 1 ~ 3 00 Fault Contour interval 100 It Contour interval 500 It o 50 Miles !I--L-., .'-1--'r-l.-~ o 75 Km e "~------l I ~ ' 1 c D : ) J i I ~~ ~ : ISO I 0 10 /1 50 I I 1 o ~ / ) ;:> Contour interval 25 It Contour interval 50 It STRATIGRAPHY 17 The Muscatatuck Group (Shaver, 1974b) Indiana. The Detroit River Formation con contains Middle Devonian carbonate rocks tains dolomites and evaporites of sabkha that are assigned to the Jeffersonville origin, porous replacement-type dolomite, Limestone and the overlying North Vernon and lithographic limestones (Doheny and Limestone in areas southwest of the Cincin others, 1975). It thickens northward from the nati Arch or to the Detroit River Formation arch from 0 to 160 feet. These units correlate and the Traverse Formation in the area north with the Grand Tower Limestone of Illinois. of the arch. Becker (1974) has described The North Vernon Limestone, which Devonian rocks southwest of the arch; contains 1 to 80 feet of variable carbonate Doheny and others (1975) have reported on rocks in southwestern Indiana, and the the Detroit River, and Droste and Shaver Traverse Formation, which consists of 0 to (1975) and Lazor (1971) have studied the more than 100 feet of fine to coarse Traverse Formation of northern Indiana. limestones and dolomitic limestones in the The basal Devonian rocks in central Indiana north, complete the Muscatatuck Group. are assigned to the Geneva Dolomite Member Rocks of the Muscatatuck Group have fair of the Jeffersonville Limestone. The Geneva potential for mineralization, especially in the ranges from 0 to 60 feet in thickness in north where breccias are noted in the Traverse central Indiana but does not occur every Formation or where solution of evaporites in where in the state. It consists of buff to the Detroit River Formation might produce brown granular dolomite that commonly open spaces or breccias and in the south contains vugs, carbonaceous laminae, crystal where the vuggy dolomitic Geneva Dolomite line calcite, and, in west-central Indiana, Member of the Jeffersonville Limestone is rounded frosted quartz. This member has present. potential as an ore host but is rather thin. The top of the Devonian section is South of the Cincinnati Arch the Jefferson represented by black organic-rich shales of the ville Limestone overlies Lower Devonian New Albany Shale. The upper part of the carbonate rocks or Silurian rocks. It thickens New Albany is Early Mississippian in age. It is southwestward from 25 to about 150 feet. separated from a thick sequence of shales and The Detroit River makes up the lower part of siltstones of the overlying Borden Group the Muscatatuck Group and overlaps various (Mississippian) by the thin Rockford Lime Silurian units in the area north of the arch. stone. None of these units are likely to be The Jeffersonville is made up of fine- to suitable hosts, although local syngenetic metal medium-grained light-brownish limestones enrichment could occur in sulfide-rich parts that are sandy, dolomitic, or cherty in places. of the New Albany Shale, which might also It thickens southwestward from 25 feet on contribute metals or sulfur. the outcrop to 1 50 feet in southwestern Figure 9 (on facing page) . Maps of Indiana showing thickness of the Black River Limestone (from Gutstadt, 1958) (A ); structure contours on top of the Trenton Limestone (from Carpenter and others, 1975; Dawson, 1971) (B); thickness of the Trenton Limestone (from Gutstadt, 1958) (C); and tbickness of the dolomite facies of the Trenton Limestone (from Gutstadt, 1958) (D). 18 POSSIBILITY OF MISSISSIPPI VALLEY·TYPE MINERAL DEPOSITS IN INDIANA EXPLANATION D Silurian rocks ab se nt __200-- Isopach contour showing thickness of Silurian rocks Contour intervsl 100 ft 0 40 Miles I I 25 0 50 Km I I I I I I I Figw:e 10. Map of Indiana showing thickness and outcrop of Silurian rocks. Modified from Becker (1974).