2020 Annual Meeting
Mt Iron, MN
May 13 & 14, 2020


ILSG Student Research Fund

Goldich Medal Guidelines and Award Winners

Eisenbrey student awards

Student paper awards

ILSG main page



A full slate of pre- and post-meeting, one-day field trips is being planned to highlight the Precambrian geology of the area.

Trip descriptions will be posted soon

Pre-Meeting trips - May 12th

1. Quetico Transect

Leader:  Mark Jirsa, (Minnesota Geological Survey)

The Quetico subprovince of the Neoarchean Superior Province represents an accretionary complex that consists largely of biotite schist derived from graywacke, diverse migmatite, and multiple granitoid intrusions.  In detail, it contains as many as 5 neosomatic intrusive phases emplaced into 3 or more supracrustal, orthogneissic, and paragneissic paleosomes, and evidence for 3 distinct episodes of deformation, one of which metamorphosed some portions to sillimanite grade.  The trip will examine exposures from north of Mountain Iron to Crane Lake, and along part of the Echo Trail. It will attempt to “unpack” the primary components of deposition, magmatism, deformation, and metamorphism that likely spanned 40 million years (~2700-2660 Ma). The trip will also address the challenge of creating meaningful geologic maps of this and similarly complex terranes, and the lithologic and temporal relationship between Quetico metasediments and those associated with successor basins in the region.

2. Alkalic and subalkalic intrusions in the Wawa and Quetico subprovinces

Leader: Terry Boerboom, (Minnesota Geological Survey)

Multiple alkalic to subalkalic intrusions that range from syenite to monzodiorite to diorite are scattered throughout the Neoarchean Wawa and Quetico subprovinces in northern Minnesota.  All are characterized by multiple ultramafic (pyroxenite, lamprophyre, appinite, etc.) to felsic phases that exhibit complex “unsolvable” commingled intrusive relationships.  Most contain conspicuously porphyritic phases in which feldspar phenocrysts are flow-aligned more or less parallel to the margins of the intrusions.  This trip will examine five of these intrusions beginning with the Side Lake pluton on the west and ending with the Idington pluton on the east.  Exposures are variable, ranging from peeled outcrops to very well-exposed roadcuts.  All are easily accessible, although some require walking up to ½ mile on a level trail.

3. Quaternary sediments, landforms and proglacial lake history in western St. Louis County

Leaders:  Kaleb Wagner and Jennifer McDonald, (Minnesota Geological Survey)

This trip will explore Quaternary sediments and landforms created by the Laurentide Ice Sheet in western St. Louis County, Minnesota, specifically the Koochiching Lobe/St. Louis Sublobe and the Rainy Lobe.  Recent mapping, conducted by the Minnesota Geological Survey (MGS), will be highlighted to demonstrate the use of geologic mapping and geochronology to reconstruct the activity of these lobes, which has progressed our knowledge of late-stage glaciations in the state.  The trip will include six stops at Quaternary exposures within sand and gravel pits.  Each site was integral to developing the geologic framework, and will include a variety of glacial sediments from the Koochiching Lobe and St. Louis Sublobe, Glacial Lake Upham, and Rainy Lobe.  We will be correlating the MGS’s mapping with Dr. Andy Breckenridge’s (University of Wisconsin - Superior) varve chronology for retreat of the Rainy lobe from the Vermilion moraine.

4. Archean rocks of the Vermilion District and underground geology at the Soudan Mine

Leaders:  George Hudak and Dean Peterson (Natural Resources Research Institute), and Mark Severson (Mesabi Range Geological Society)

The Vermilion district of northeastern Minnesota is a classic Neoarchean granite-greenstone terrain comprising generally greenschist-facies metamorphosed intrusive/volcanic rocks, clastic and chemical sedimentary rocks, and a variety of structurally deformed and sheared rocks. The first portion of the trip will view newly created roadcuts along a portion of Highway 169.  Rocks in this area consist of ~2722 – 2700 Ma Soudan Iron-Formation and associated metadiabasic and dacitic sills, volcanic fragmental rocks, and a unique “epidosite”/peperite.  The middle portion of the trip will visit similar rocks within the nearby Lake Vermilion-Soudan Mine State Park highlighting volcaniclastic rocks associated with the ~2689 Ma Gafvert Lake sequence.  The final stops will comprise an underground walking tour of the 27th Level (depth 2,341 ft.) at the Soudan Mine to view the lithology, structure, and hydrothermal alteration associated with massive hematitic iron ore deposits that were mined for 78 years (1884-1962).

Syn-meeting trips - May 14th

5. Eveleth Fee Office

Leader:  Dan England (Eveleth Fee Office, Eveleth Minnesota)

This trip visits the historic Eveleth Fee Office, which was established in 1905 to manage iron ore mineral interests on the Mesabi Range.  You will learn about the Fee Office’s purpose and 115-year history. Dan’s mineral collection is currently housed at the office, and he will give a tour of the spectacular mineral specimens he has acquired from around the globe during 54 years of collecting.  A must-see trip for the mineral collector or Iron Range history buff.

6. Minnesota Department of Natural Resources Drill Core Library

Leaders: Dave Dahl and Stacy Saari, (Minnesota Department of Natural Resources - Division of Lands and Minerals)

This afternoon trip will involve a drive of 20 miles to Hibbing to tour the core library facilities and view a suite of core types representative of the geologic terranes of Minnesota, including cores from areas that host copper, nickel, platinum group elements, titanium, manganese, iron, and gold.  In addition, staff will be available to explain examination and sampling procedures at the library.  If time permits, a stop will be made at the new Hull-Rust mine overlook, which offers an expansive view over the Hibbing Taconite open-pit mining operations and the City of Hibbing.

Post-meeting trips - May 15th

7. Cu-Ni mineralization at Polymet Mining, and the Colvin Creek inclusion in the Partridge River intrusion, Duluth Complex

Leaders:  Mark Severson (retired); Andrew Ware, Polymet Mining

This field trip is two tiered. The morning will consist of viewing core from recent drilling by PolyMet at their proposed NorthMet Mine into the Magenta Zone.  The Magenta Zone differs from typical basal mineralization in that it is situated well above the basal contact, and shallowly down-cuts the layered igneous units of the Partridge River intrusion in a northward direction.  This horizon is also unique in that it is PGE-enriched and chalcopyrite is the dominant sulfide. The afternoon will visit spectacular outcrops of the Northern Colvin Creek body—a near-vertical sandstone and basaltic hornfels inclusion (2,500 meters by 800 meters) within the Partridge River intrusion.  The inclusion consists of a sequence of contact-metamorphosed magnetic basalts, overlain by 350 meters of cross-bedded, quartz-deficient, very fine-grained sandstone with pyroxene porphyroblasts.  The second portion of the trip involves a moderate degree of walking along a logging road and some bushwhacking along short flagged trails.

8. Tamarack Ni-Cu deposit, Ely’s Peak basalt, and Thomson Formation

Leaders:  Terry Boerboom (Minnesota Geological Survey) and Brian Goldner (Talon Metals Corp.)

The main focus of this trip is to examine select drill core from the Tamarack Ni-Cu deposit, hosted in the ca. 1105 Ma mafic-ultramafic Mesoproterozoic Tamarack intrusion.  There will also be a stop at Thomson Dam to examine the Paleoproterozoic Thomson Formation, the host-rock to Tamarack, which is intruded by Mesoproterozoic diabase dikes.  A third stop will visit a quarry developed in the Mesoproterozoic Ely’s Peak basalt – the lowest flow in the reversely-polarized southwest limb of the North Shore Volcanic Group.  The last stop may not be available, depending on current operations in the quarry, in which case an alternate stop will examine the contact between the base of the Ely’s Peak basalt and Nopeming Sandstone.  Because this trip involves a 1.5 hour drive from Mountain Iron we will work out a meeting point near Duluth where participants may leave their vehicles if they wish.

9. Western Mesabi Range minerals, mining, and fossil-hunting tour

Leaders: Amy Block, (Minnesota Geological Survey), and personnel from the Natural Resources Research Institute, Hawkinson Construction, Minnesota Department of Natural Resources, and the Science Museum of Minnesota.

This trip will visit the (1.) Natural Resources Research Institute (NRRI) Coleraine research laboratory including minerals processing analytical, bench-scale, and pilot scale metallurgical laboratories and the biomass conversion laboratory; (2.) A small quarry developed in the Pokegama Quartzite which forms the footwall to the Biwabik Iron Formation; and (3) a tour of the historic Hill Annex iron mine.  More than 63 million tons of hematitic ‘natural ore’ was extracted from this mine; the ore included both oxidized iron formation as well as the overlying Cretaceous conglomerate composed predominantly of rounded cobbles of reworked oxidized iron-formation.  Part of the trip will set aside time to hunt for sharks teeth, ‘clams and snails’, and ammonites!

10. Iron Mines of the central Mesabi range

Leaders:  Phil Larson (Hibbing), Doug Halverson (United), Steven Losh, Minnesota State University - Mankato and Mark Jirsa (MGS)

This trip visits 2 operating taconite mines; Hibbing Taconite in Hibbing, and United Taconite in Eveleth, to compare and contrast various lithologic and structural aspects of the Paleoproterozoic Biwabik Iron Formation and associated strata.  2020 marks the 125th year of continuous iron ore mining in Hibbing by Hibbing Taconite Company and its corporate predecessors. Since 1976, Hibbing Taconite has exclusively mined magnetite taconite from the Lower Cherty member of the Biwabik Iron Formation.  United Taconite has been in operation since 1965, mining both Upper and Lower Cherty members of the Biwabik. The long history of mining at both locations has produced excellent exposures of unoxidized BIF in pit walls. In addition, remnants of the direct shipping and wash grade ores (oxidized) mined between 1897-1973 are visible locally in old pit walls. This field trip will provide an opportunity to visit exposures of lower Animikie Group strata (Pokegama and Biwabik Iron Formations). In addition, exposures highlighting controls on the occurrence of oxidized and desilicified iron formation transitional between taconite and direct shipping ore are accessible.



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