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Item Bulletin No. 29. The Paleozoic and Related Rocks of Southeastern Minnnesota(Minnesota Geological Survey, 1941) Stauffer, Clinton R.; Thiel, George A.The area covered by this report is mainly the southeastern part of Minnesota. It includes that portion of the state lying along or bounded by the St. Croix, the Minnesota, and the Mississippi rivers from Pine County southward to the Iowa state line and from Brown County eastward to the Wisconsin state line. Adjoining areas are referred to at various points in the text, chiefly for correlative purposes or in order to clarify the discussion. This area lies mostly within the hardwood timber section. Numerous towns and villages dot the region, which is part of the more thickly populated area of Minnesota, settled for over seventy-five years and first pioneered over one hundred years ago. Many of the old traders and missionaries traveled its navigable waters early in the seventeenth century; and for untold centuries before that it was an important part of the great hunting ground of the American Indian. The state of Minnesota lies on the southern border of the great Canadian Shield, so that much of its surface is covered by the preCambrian rocks characteristic of that ancient land mass. There more recent sediments overlie these older rocks, they vary in age from Cambrian to Cretaceous and later, for the glacial drift and the recent non-marine sediments may lie directly on the preCambrian. The strand line of Paleozoic and late Mesozoic time often passed through Minnesota; and the position of the ancient shore, varying from time to time, left many unconformities. The significance of some of these unconformities may not yet be fully appreciated, but they range from short breaks (diastems) in sedimentation, like those in the St. Croixian series, to great erosion intervals (disconformities) like that between the Maquoketa formation and the Cedar Valley limestone, where a whole system and fully half of another are wanting. It is evident, therefore, that during these long intervals diastrophism caused the land mass to the north to be extended beyond the boundaries of the state and that during such periods profound erosion must have affected this area, removing an unknown amount of the surface, probably base-leveling it several times.Item Guidebook 15. Field Trip Guidebook for the Upper Mississippi Valley Minnesota, Iowa, and Wisconsin(Minnesota Geological Survey, 1987) Balaban, N.H., EditorCONTENTS KARST HYDROGEOLOGY OF SOUTHEASTERN MINNESOTA, E. Calvin Alexander, Jr. THE GEOLOGY OF THE ST. CROIX RIVER VALLEY, Mark E. Cavaleri, John H. MossIer, and Gerald F· Webers INTRODUCTION TO THE MIDDLE AND LATE ORDOVIClAN FIELD TRIPS, Robert E. Sloan THE MIDDLE ORDOVICIAN FOSSILS OF THE TWIN CITIES, MINNESOTA, Robert E. Sloan, William F. Rice, Eric Hedblom, and James M. Mazzullo THE MIDDLE AND LATE ORDOVICIAN STRATA AND FOSSILS OF SOUTHEASTERN MINNESOTA, Robert E. Sloan and Dennis R. Kolata THE MIDDLE AND LATE ORDOVICIAN STRATA AND FOSSILS OF IOWA, Dennis R. Kolata and Robert E. Sloan THE ROCK ELM DISTURBANCE, PIERCE COUNTY, WISCONSIN, William S. Cordua QUATERNARY GEOLOGY OF SOUTHEASTERN MINNESOTA, Howard C. HobbsItem 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.