Browsing by Author "Mossler, John H."
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Item Educational Series 10. Geology of the Root River State Trail Area, Southeastern Minnesota(Minnesota Geological Survey, 1999) Mossler, John H.The Root River State Trail is a paved walking, bicycling, and cross- country skiing trail in southeastern Minnesota that currently extends from the town of Fountain through Lanesboro to Rushford, and farther east towards Houston. It is maintained by the Minnesota Department of Natural Resources, which operates a trail information center in Lanesboro. The Rushford Historical Society operates a trail rest area in Rushford. The trail is part of a planned network of trails throughout southeastern Minnesota, that will ultimately extend into Iowa and Wisconsin. This guide was developed for the Fountain to Rushford segment of the Root River State Trail, but the information will help you learn more about geologic features you see anywhere in southeastern Minnesota. The Root River State Trailtraverses the unique landscape of Minnesota's 'Historic Bluff Country,' and provides us with a birds-eye- view into the processes that have been forming the rocks and the land surfaces in this part of Minnesota during the past 500 million years. Flat- lying layers of limestone and dolostone form high bluffs above narrow river valleys, such as the Root River valley. The limestone uplands are intensively farmed, but many of the fields contain pits or depressions, called sinkholes, that surface water drains into. The sinkholes are usually overgrown with burr oak, stinging nettle, woodbine, and wild cherry. The Root River has eroded a steep-sided valley into the layers of limestone and dolostone. At the base of the cliffs, water that drained into the sinkholes on the uplands emerges as springs, having traveled through passageways in the limestone and dolostone. This booklet summarizes the history of the rocks that you see as you explore the Root River State Trail, and presents a field guide to features of geologic interest.Item Information Circular 41. Geochemical Investigation of Minor and Trace Elements in the Acid-Insoluble Residues of Lower Paleozoic Carbonate and Related Strata, Southeastern Minnesota-The Data Base(Minnesota Geological Survey, 1994) Morey, G.B.; Lively, R.S.; Mossler, John H.; Hauck, S.A.The Upper Mississippi Valley mining district in Iowa, Wisconsin, and Illinois is one of several world-class lead-zinc mineral districts in developed Paleozoic strata of the northern Midcontinent. Although Mississippi Valley-type deposits vary considerably from district to district, they are defined as being predominantly sphalerite-galena replacement and vein deposits-including vug and breccia fillings-in carbonate host rocks. In general, they are restricted to certain formations; as such they are peneconformable but clearly crosscutting. Therefore, Mississippi Valley-type mineral deposits are epigenetic and stratabound, but not stratiform. Minor occurrences of base-metal sulfides also are present in calcareous and, to a lesser extent, in shaly and sandy rocks in a broad zone surrounding the main Upper Mississippi Valley lead-zinc district. These outlying occurrences are of special interest because similarities in form, distinctive mineral paragenesis, and sulfur and lead isotope systematics imply that they were cogenetic with mineralization in the main district. The outlying occurrences may represent remnants of fluid pathways associated with mineralization in the main district. To evaluate the extent of mineralization in southeastern Minnesota, we initiated a geochemical study that focused on the minor-and trace-element content of insoluble residues in carbonate rocks, using samples from drill holes and operating quarries throughout southeastern Minnesota (Fig. 2; Tables 4-52 in appendix). Regional geochemical studies of this kind have revealed, even in rocks that appear to be barren of sulfide ores, a suite of metals characteristic of Mississippi Valley-type mineral deposits. In particular, this suite includes Pb, Zn, As, Cu, Ni, Ca, Ag, and Mo. Geochemical analysis of insoluble residues from Paleozoic carbonate rocks has become an integral part of the assessment of mineral resources in the northern Midcontinent (Erickson and others, 1981, 1983; Mosier and Motooka, 1983; Viets and others, 1983). Insoluble residues are the materials remaining after calcium carbonate has been dissolved in a aqueous solution of 5:1 hydrochloric acid. Measurements of the minor-and trace- element composition of the residues provide a rapid, yet sensitive means of identifying regional ground-water flow patterns of metal-bearing brines. The method also appears to have some applicability in identifying previously unrecognized areas with Mississippi Valley-type lead- zinc deposits and, by extension, providing clues to possible locations of mineral deposits in southeastern Minnesota.Item M-194 Bedrock Geology of the Twin Cities Ten-County Metropolitan Area, Minnesota(2013-08-01) Mossler, John H.This regional map is partly a compilation of existing maps of bedrock geology in the metropolitan area and partly a remapping of bedrock in areas where the existing maps were out of date because of the acquisition of new subsurface data.Item RI-18 Cedar Valley Formation (Devonian) of Minnesota and Northern Iowa(Minnesota Geological Survey, 1978) Mossler, John H.Item RI-19 Results of Subsurface Investigations in Northwestern Minnesota, 1972(Minnesota Geological Survey, 1978) Mossler, John H.Two test wells were drilled in northwestern Minnesota during a test drilling program conducted by the Minnesota Geological Survey in 1972. Total footage drilled was 851.5 feet (260 m). Together, the wells represent a relatively complete stratigraphic section of the Paleozoic and Mesozoic rocks found in northwestern Minnesota, which are covered by thick Pleistocene overburden and do not crop out. Four stratigraphic units are present. The basal unit is the Winnipeg Formation, a Middle Ordovician unit approximately 160 feet (49 m) thick composed of quartzose sandstone and shale. It is overlain by the Red River Formation, an Upper Ordovician unit about 200 to 300 feet (61 to 91 m) thick composed of dolomitic limestone and dolomite. The other two units are interpreted to be Mesozoic. The lower unit is a reddish-brown shale with a thin layer of dolomite at the top. It is as much as 105 feet (32 m) thick in Minnesota. It may be equivalent to the red beds in adjoining parts of Manitoba and North Dakota that are assigned a Jurassic age, although no paleontologic evidence was found to indicate its age. The uppermost unit is a gray shale that is provisionally interpreted to be Cretaceous. Two tills can be recognized in the Pleistocene section on the basis of the lithology of the sand-size fraction and size-grade distribution. The surficial Pleistocene unit is clay associated with Glacial Lake Agassiz. The Precambrian basement in the area is principally volcanogenic metasedimentary rock and metamorphosed volcanic rock of Early Precambrian age. It was penetrated in one well where it is represented by actinolitic hornblende-plagioclase schist, a mafic, tuffaceous, sedimentary rock that has been metamorphosed.Item RI-33 Sedimentology of the Middle Ordovician Platteville Formation Southeastern Minnesota(Minnesota Geological Survey, 1985) Mossler, John H.The Platteville Formation, a thin Middle Ordovician unit, is subdi vided into several members in Minnesota. The basal Pecatonica and upper Carimona Members are present throughout all the Minnesota/western Wisconsin outcrop belt. The medial McGregor, which is recognized in the southern part of the Minnesota outcrop, is replaced by the Mifflin, Hidden Falls, and Magnolia Members in the Twin Cities area. Distribution of the Mifflin is restricted to the Twin Cities structural basin; the other two units extend slightly beyond the Twin Cities basin. Their distribution may have been influenced by proximity to a paleoshoreline north of the present outcrop. The Platteville Formation was deposited in a transgressing sea as part of the Middle Ordovician-Silurian Tippecanoe sequence. It is interpreted to have been deposited on a shallow marine shelf in deeper water than the shoreward facies represented by the underlying St. Peter Sandstone and Glenwood Formation. Fossils of stenohaline organisms are present throughout the formation. The formation has no exposure indicators, stromatolites, or intraclasts. Features indicative of shallower water, such as ferruginous ooids and coquina layers, are present in the Twin Cities/western Wisconsin area. Hardgrounds--surfaces of submarine nondeposition indicative of low rates of sedimentation--characterize the Pecatonica and lower McGregor Members, but are less common in the upper part of the formation. The Carimona Member is characterized by limestone beds separated by shale beds and partings that thicken toward the west and north. This increased detrital sedimentation during deposition of the Carimona Member and the succeeding Decorah Shale may indicate uplift along the Transcontinental Arch. The proportion of dolomi te to calci te in the carbonate rocks of the Platteville increases toward the north and northeast. In southern Minnesota the formation is principally limestone; in the Twin Cities Metropolitan Area and western Wisconsin, it has a high proportion of dolomite. The formation does not have any diagenetic fabrics indicative of subaerial exposure, and deposition of the overlying Decorah Shale appears to have followed deposition of the Platteville without interruption. The pervasive dolomitization is probably a result of burial diagenesis.Item RI-36 Paleozoic Lithostratigraphic Nomenclature for Minnesota(Minnesota Geological Survey, 1987) Mossler, John H.Significant changes are made in stratigraphic nomenclature for the Paleozoic formations of Minnesota that reflect subsurface data acquired since 1969 and accord with changes in nomenclature in adjoining states. For the Cambrian section, dolostone that intertongues with the lower part of the Eau Claire Formation in the subsurface of south-central and southwestern Minnesota is interpreted to be a tongue of the Bonneterre Formation of northwestern Iowa. The Reno Member of the Franconia Formation, together with the Birkmose Member, is now interpreted to compose most of the formation, whereas the Tomah Member is now interpreted to have very restricted subsurface distribution; an additional dolostone member, here informally named the Davis, is recognized in the subsurface in south-central Minnesota. The uppermost member of the overlying Jordan Sandstone is here renamed the Coon Valley Member. For the Ordovician section, the Galena is now elevated to group status. The Cummingsville Formation, Prosser Limestone, and Stewartville Formation-formerly members of the Galena--now correspond in rank with their equivalents in adjoining states. In the Devonian sequence, formerly classified as entirely Cedar Valley Formation in Minnesota, the recently named Spillville Formation is recognized in the base of the sequence, and the Wapsipinicon Formation is now known to extend into Minnesota from Iowa. The name Cedar Valley is retained for the overlying Devonian rock unit.Item RI-40 Sedimentary Rocks of Dresbachian Age (Late Cambrian), Hollandale Embayment, Southeastern Minnesota(Minnesota Geological Survey, 1992) Mossler, John H.The Dresbachian Mt. Simon Sandstone, Eau Claire Formation, and Galesville Sandstone of the Hollandale embayment of southern Minnesota are divisible into eleven major lithofacies and several subfacies. Because the formations are almost exclusively in the subsurface in Minnesota, lithofacies descriptions are based on cores, well cuttings, and geophysical logs. Along the eastern side of the Hollandale embayment, the lower Mt. Simon Sandstone consists of a thin basal conglomerate lithofacies overlain by medium- and large-scale, crossstratified and planar-stratified sandstone. Middle Mt. Simon is principally interbedded, coarsely interlayered sandstone, siltstone, and shale; and thin- to medium-bedded, structureless or crossstratified sandstone. The upper Mt. Simon is structureless sandstone with Skolithos and shelly (coquinoid) sandstone. These lithofacies resemble those from outcrops in western Wisconsin described by Driese and others (1981). Toward the west and south in south-central Minnesota, at the embayment center, mediumand large-scale, cross-stratified sandstone dominates in the Mt. Simon. Along the western side of the embayment, structureless sandstone dominates. There are fewer thin shale and siltstone beds in the Mt. Simon near the embayment center than along the eastern side of the embayment. Near the embayment center, the uppermost Mt. Simon Sandstone and basal Eau Claire Formation contain ferroan oolites and coated grains that are scattered in some beds and are the principal sand-sized particles in others. Ferroan oolites and coated grains are not observed in outcrop. Along the eastern side of the Hollandale embayment, the Eau Claire is composed principally of mixed sandstone and shale lithofacies and greensand lithofacies resembling Eau Claire lithofacies that crop out in western Wisconsin (Huber, 1975), especially in cores along structural strike with the Wisconsin outcrops. Red sandstone and shale lithofacies and dolostone lithofacies are at the base of the Eau Claire in south-central Minnesota. These are overlain by a ripple-cross-stratified or troughcross- stratified subfacies of the greensand lithofacies that is much thicker than laterally equivalent beds of greensand lithofacies to the north and east. The Galesville Sandstone, mostly structureless, planar-stratified, or trough-cross-stratified sandstone, appears to be conformable and interbedded with the Eau Claire Formation. The upper part of the Eau Claire and Galesville appear to be part of an upward coarsening sequence. There is evidence of slight disconformity between the Galesville and overlying Ironton Sandstone. The basal conglomerate of the Mt. Simon is interpreted as a braided fluvial deposit. Medium- to coarse-grained sandstone lithofacies of the lower Mt. Simon are interpreted as braid plain, braid delta, and littoral deposits. Fine- to medium-grained sandstone beds and shale beds in the middle Mt. Simon are interpreted as distal braid delta deposits. Sandstone beds in the upper Mt Simon are interpreted as sand shoals and tidal flat deposits. Beds of interbedded, finegrained sandstone and shale in the basal Eau Claire that are tidal flat deposits culminate this initial prograding sequence. Toward the end of the sequence deposition, ferroan oolites formed nearshore, where some were reworked by shifting tidal channels. Red sedimentary rocks were deposited in high tidal flat, channel, and deltaic environments. Carbonate rock was deposited in the southwestern Hollandale embayment as detrital sedimentation ended. The greensand lithofacies of the medial Eau Claire Formation, which records marine transgression at the base of the next prograding sediment sequence, is succeeded by shaly lagoonal deposits, sandy or shaly tidal flat deposits (upper Eau Claire Formation), and sandy foreshore or shoreface deposits (Galesville Sandstone). Variation of sandstone composition reflects selective mechanical reduction of contained potassium feldspar grains as observed by Odom (1975). Medium- to coarse-grained sandstone is quartzose, and very fine to fine-grained sandstone is highly feldspathic. This variation, reflected on gamma logs, helps to distinguish lithofacies. . Sandstone in core from southwestern Minnesota contains accessory minerals, including diaspore, that indicate the contribution of sediment from the Proterozoic Sioux Quartzite to the Mt. Simon Sandstone.Item RI-65 Paleozoic Stratigraphic Nomenclature for Minnesota(Minnesota Geological Survey, 2008) Mossler, John H.Item S-15 Geologic Map of Minnesota, Bedrock Topography(Minnesota Geological Survey, 1982) Olsen, Bruce M.; Mossler, John H.Item S-21 Geologic Map of Minnesota-Bedrock Geology(Minnesota Geological Survey, 2011) Jirsa, Mark A.; Boerboom, Terrence J.; Chandler, V.W.; Mossler, John H.; Runkel, Anthony C.; Setterholm, Dale R.This map is a new construct that incorporates existing geologic maps where prior mappers had adequate ground control, and new interpretations based on drill hole, geophysical, and unpublished data where they did not. The interpretation differs significantly from previous maps to reflect new data and accommodate scale. It portrays our current geologic understanding of the temporal and geographic distribution of units within major Precambrian terranes and of the Phanerozoic strata. The western part of the mapped Precambrian terrane is inferred largely from geophysical maps, anchored locally by drilling. In many places, contacts are drawn between units of the same or similar apparent rock type (and same unit label); these are recognized as geometrically distinct, though geophysically or lithologically similar. Digital files corresponding to this map allow removal of Cretaceous, Paleozoic, and some parts of Mesoproterozoic strata to reveal an interpretation of the underlying Precambrian bedrock. For additional data see: (http://hdl.handle.net/11299/98043 [select, copy and paste into browser]) which contains files associated with Bedrock Topography, Depth to Bedrock, and locations of Outcrop and Geochronologic analyses.