Industrial minerals of the Upper Midwest; Proceedings of the 51st Forum on the Geology of Industrial Minerals, presented in cooperation with the Annual Conference of the Twin Cities Subsection of the Society for Mining, Metallurgy & Exploration (SME), August 17 – 20, 2015

Among the 17 presenters who spoke at the 51st Forum on the Geology of Industrial Minerals, cohosted in August 2015 by the Twin Cities Subsection of SME, 7 contributed a paper to the Proceedings, which are here released by Minnesota Geological Survey.On August 17 – 20, 2015, the Twin Cities Subsection of the Society for Mining, Metallurgy & Exploration (SME) hosted the 51st Forum on the Geology of Industrial Minerals. The theme of the meeting, whose conference sessions and field trips were enjoyed by about 100 people, was ‘Industrial minerals of the Upper Midwest’. SME, headquartered in Denver, is a professional society whose more than 15,000 membership represents all professionals serving the minerals industry in more than 100 countries. SME advances the worldwide mining and underground construction community through information exchange and professional development. In Minnesota, the SME Minnesota Section maintains a broad program of activities that focuses on the annual spring conference in Duluth. The SME Twin Cities Subsection organizes an annual autumn conference, monthly luncheons, student activities, and social functions. Following a hiatus, the SME Twin Cities Subsection annual conference was restarted in 2011. For 2012 and subsequent years, the subsection has worked with a different partner each year, to present a conference program aligned with broad mining-related topics, while focusing on the sort of mining that takes place in the Twin Cities region, such as crushed stone, sand and gravel, and silica sand. For 2015, the SME Twin Cities Subsection was pleased to work in cooperation with organizers of the Forum on the Geology of Industrial Minerals. The Forum meets regularly, and it has been customary for a proceedings volume to be produced. Among the 17 presenters who gave presentations at the 2015 Forum, seven chose to contribute a paper. The Minnesota Geological Survey is pleased to have an opportunity to support the activities of SME and the Forum by facilitating availability of the 2015 Proceedings of the 51st Forum on the Geology of Industrial Minerals.Forum on the Geology of Industrial Minerals Twin Cities Subsection of the Society for Mining, Metallurgy & Exploratio

The Middle Wisconsinan History of the Laurentide Ice Sheet

Evidence for Middle Wisconsinan ice limits and climates comes from sites scattered around the periphery of the Laurentide Ice domain and from the Hudson Bay Lowlands. Interpretations are based on dated wood, peat, shell and sediment; biological climate indicators (chiefly cool-climate indicators); and stratigraphie sequences of both glacial and nonglacial units. The best evidence comes from the prairie provinces and the Great Lakes areas, both of which indicate substantial ice retreat from earlier southern glacial limits, and cool, boreal-tundra climates. The western arctic may have experienced an early warm period but both the western arctic — northwestern plains and eastern maritime areas may later have become ice accumulation areas. Three maps portray various possible ice limits. The first shows substantial ice cover in the arctic, but reduced ice cover in the prairies and Great Lakes, and expanded maritime ice caps (rather than Laurentide Ice) in the southeast and on Baffin Island. This ice mass distribution may reflect Middle Wisconsinan shifts in air masses and ocean currents. Ice volumes generated by this model are in accord with the marine oxygen isotope record and perceived global sea level changes. A modification to this model, which resolves some of the controversy in the Hudson Bay Lowlands, shows a calving bay penetrating into the heart of the ice sheet, induced by dynamic instability of the marine-based ice mass in Hudson Bay during relatively high glacial isostatic and eustatic seas. A third reconstruction portrays extensive climatically induced déglaciation and retains Laurentide ice only in parts of the northwest and Labrador-Ungava, with local ice in the Appalachian-Atlantic region. This model is based on alternative genetic interpretations of lithologic units and reassessment of age assignments.Les indices sur les limites glaciaires et les climats du Wisconsinien moyen proviennent d'endroits situés en bordure de la calotte glaciaire laurentidienne et des basses terres de la baie d'Hudson. Les interprétations se fondent sur la datation du bois, de la tourbe, des coquilles et des sédiments, sur les indicateurs biologiques de climat et sur les séquences stratigraphiques des unités glaciaires et non glaciaires. Les meilleurs indices proviennent des Prairies et des Grands Lacs; ils révèlent un recul marqué de la glace à partir des limites méridionales antérieures et des climats frais de type boréal ou de toundra. L'ouest de l'Arctique a peut-être initialement connu une période chaude, mais cette région, les plaines du nord-ouest et les Maritimes seraient par la suite devenues des zones d'accumulation de glace. Trois cartes montrent les diverses limites glaciaires proposées. Dans la première, la couverture glaciaire est très étendue dans l'Arctique et moins étendue dans les Prairies et les Grands Lacs; on y voit de grandes calottes glaciaires maritimes dans le sud-est et dans l'île de Baffin. Cette répartition de la glace pourrait résulter du déplacement des masses d'air et des courants océaniques au cours du Wisconsinien moyen. Un autre modèle, légèrement différent, résout certains problèmes associés aux basses terres de la baie d'Hudson; la baie de vêlage, qui s'avance jusqu'au centre de l'inlandsis, est le produit de l'instabilité dynamique de la masse glaciaire marine dans la baie d'Hudson. Un troisième modèle fait voir une déglaciation étendue provoquée par des changements climatiques; la glace laurentidienne persiste uniquement à certains endroits dans le nord-ouest, dans la région du Labrador et de l'Ungava et dans la zone appalachienne atlantique.Anhaltspunkte fur Eisgrenzen und Klima im mittleren glazialen Wisconsin ergeben sich aus Plätzen, die um die Peripherie des von der laurentischen Eisdecke bedeckten Gebiets verstreut sind, sowie aus dem Tiefland der Hudson Bay. Die lnterpretationen grunden sich auf datiertes HoIz, Torf, Muscheln und Sedimente, biologische Klimalndikatoren und die stratigraphischen Abfolgen sowohl glazialer als auch nichtglazialer Einheiten. Die besten Zeugnisse stammen aus den PrärieProvinzen und dem Gebiet der Gro(3en Seen. Aus beiden Regionen zeigt sich ein bedeutender EisRückgang von den früheren sud-lichen Eisgrenzen und kühles nördliches Tundra-Klima. In der westlichen Arktik mag wohl eine frühe warme Période aufgetreten sein, aber sowohl die westarktischen Ebenen als auch die ôstlichen Meeres-Gebiete sind wohl später Gebiete starker Vereisung geworden. Drei Karten illustrieren verschiedene mögliche Eisdecken. Die erste zeigt eine beträchtliche Eisdecke in der Arktis, jedoch in den Prärien und dem Groften Seen-Gebiet eine geringere Eisdecke und im Südosten und auf der Baffin-lnsel ausgedehnte Meeres-Eiskappen. Diëse Verteilung der Eismasse mag die Folge von Verschiebungen von Luftbewegungen und ozeanischen Strömungen sein. Eine Abweichung von diesem Modell, welche einige der Kontroversen im Hudson-Bay Tiefland klärt, zeigt eine Kalbungs-Bucht, welche in den Kern der Eisdecke vordringt. Diëse Bucht wurde durch die dynamische Instabilität der marinen Eismasse in der Hudson-Bay während relativ hoher glazialisostatischer und eustatischer Gezeiten hervorgerufen. Ein drittes Modell beschreibt ausgedehnte klimatisch bedingte Enteisung und zeigt laurentisches Eis nur in Teilen des Nordwestens und von Labrador-Ungava mit örtlich begrenztem Eis im Gebiet der Atlantik-Appalachen

An updated radiocarbon-based ice margin chronology for the last deglaciation of the North American Ice Sheet Complex

The North American Ice Sheet Complex (NAISC; consisting of the Laurentide, Cordilleran and Innuitian ice sheets) was the largest ice mass to repeatedly grow and decay in the Northern Hemisphere during the Quaternary. Understanding its pattern of retreat following the Last Glacial Maximum is critical for studying many facets of the Late Quaternary, including ice sheet behaviour, the evolution of Holocene landscapes, sea level, atmospheric circulation, and the peopling of the Americas. Currently, the most up-to-date and authoritative margin chronology for the entire ice sheet complex is featured in two publications (Geological Survey of Canada Open File 1574 [Dyke et al., 2003]; ‘Quaternary Glaciations – Extent and Chronology, Part II’ [Dyke, 2004]). These often-cited datasets track ice margin recession in 36 time slices spanning 18 ka to 1 ka (all ages in uncalibrated radiocarbon years) using a combination of geomorphology, stratigraphy and radiocarbon dating. However, by virtue of being over 15 years old, the ice margin chronology requires updating to reflect new work and important revisions. This paper updates the aforementioned 36 ice margin maps to reflect new data from regional studies. We also update the original radiocarbon dataset from the 2003/2004 papers with 1541 new ages to reflect work up to and including 2018. A major revision is made to the 18 ka ice margin, where Banks and Eglinton islands (once considered to be glacial refugia) are now shown to be fully glaciated. Our updated 18 ka ice sheet increased in areal extent from 17.81 to 18.37 million km2, which is an increase of 3.1% in spatial coverage of the NAISC at that time. Elsewhere, we also summarize, region-by-region, significant changes to the deglaciation sequence. This paper integrates new information provided by regional experts and radiocarbon data into the deglaciation sequence while maintaining consistency with the original ice margin positions of Dyke et al. (2003) and Dyke (2004) where new information is lacking; this is a pragmatic solution to satisfy the needs of a Quaternary research community that requires up-to-date knowledge of the pattern of ice margin recession of what was once the world’s largest ice mass. The 36 updated isochrones are available in PDF and shapefile format, together with a spreadsheet of the expanded radiocarbon dataset (n = 5195 ages) and estimates of uncertainty for each interval

OFR18-01, Geologic Mapping Forum Abstracts

Abstracts for the Geologic Mapping Forum conference in Minneapolis from March 27th to 29th, 2018At the Geologic Mapping Forum in Minneapolis from March 27th to 29th, 2018, ~100 geological map authors, program managers and allied professionals from geological surveys and allied agencies met to discuss the status and future of geologic mapping in the USA. The meeting was hosted by Minnesota Geological Survey on the University of Minnesota campus. The meeting was held near the Mississippi River, at the Humphrey School of Public Affairs on the West Bank campus, in the Humphrey School Conference Center at 301 19th Avenue South, Minneapolis, MN 55455. Unless they had been invited to speak in a plenary, all participants were urged to present a 15-minute talk in a concurrent session or a poster. Plenary, concurrent session, and poster presenters were asked to submit a 1 to 2-page abstract. The meeting commenced with registration and a reception at the hotel with light food and drinks on Monday from 5 to 7 PM, followed by conference sessions from 8:30 AM Tuesday until 4:30 PM Thursday

OFR11-02, Potential for Implementation of Mineral Carbonation as a Carbon Sequestration Method in Minnesota

Minnesota, with a population of about five million, is a significant source of greenhouse gas emissions, and a state that is vulnerable to climate change, such as the impact that increased frequency or severity of drought or storms would have on agriculture, water supply, wildlife, lake levels, and public security. Minnesota therefore has an interest in reducing our own vulnerability, while concurrently contributing to needed world-wide solutions. As has been stressed, for example, in documents prepared for and by the Minnesota Climate Change Advisory Group, emissions reductions can have multiple benefits, including conservation, cost efficiency, and air quality enhancement, while also directly contributing to mitigation of climate change. Anthropogenic climate change seems already to have begun, however, so adaptation to climate change accompanies mitigation in the climate change policy agenda. Mitigation of greenhouse gas emissions can be achieved through reduced fossil fuel combustion, while concurrently capturing and storing carbon in biomass, or in geologic repositories. It has become apparent that the best approach is likely to be for several options to concurrently be implemented. Minnesota may be well positioned to utilize the mineral carbonation method of geologic carbon sequestration, given the presence of vast tonnages of appropriate rock material in the Duluth region, some of which could be mined for copper, nickel, and platinum group elements, pending the outcome of current permitting procedures. Should these deposits go into production, a slurry of minerals suitable for mineral carbonation of CO2 would be produced as a waste product from the mines. The principal constraint to mineral carbonation at present appears to be cost. Nevertheless, there could be developments in the method, and there could be circumstances in which a particularly favorable mineral carbonation opportunity could coincide with constraints to other aspects of the sequestration procedure, such as considerations regarding transportation, thus possibly making mineral carbonation a conceivable option.Minnesota Minerals Coordinating Committe

OFR19-1, Geologic Mapping Forum 2019 Abstracts

Abstracts for the Geologic Mapping Forum conference in Minneapolis from April 10 to 12, 2019At the Geologic Mapping Forum in Minneapolis from April 10th to 12th, 2019, ~100 geological map authors, program managers and allied professionals from geological surveys and associated agencies met to discuss the status and future of geologic mapping in the USA and neighboring countries. The meeting was hosted by the Minnesota Geological Survey on the University of Minnesota campus. The meeting was held at the Humphrey School of Public Affairs on the West Bank campus, in the Humphrey School Conference Center at 301 19th Avenue South, Minneapolis, MN 55455. Participants were invited to present a 30-minute plenary or 15-minute talk, or a poster, and submitted a 1 to 2-page abstract published in this Open File. The meeting opened with registration and a reception on Tuesday evening followed by conference sessions beginning at 8:30 AM Wednesday and ending 2:30 PM Friday. Regional organization business meetings followed on Friday afternoon and Saturday

OFR21-01, Geologic Mapping Forum 20/21 Abstracts

Abstracts for the Geologic Mapping Forum conference held online in late 2020 and early 2021Due to the coronavirus pandemic, the Geologic Mapping Forum for 2020 and 2021 was held online as monthly meetings from October 2020 to April 2021. As many as 140 geological map authors, program managers and allied professionals from geological surveys and associated agencies attended, to discuss the status and future of geologic mapping in the USA and neighboring countries. The meeting was hosted by the Minnesota Geological Survey of the University of Minnesota. Participants were invited to present a 20-minute minute talk, and were given the option to submit a 1 to 2-page abstract published in this Open File