Marquette Range Research Articles

A Revision of Stratigraphic Nomenclature for Middle Precambrian Rocks in Northern Michigan

The name Marquette Range Supergroup is proposed to supplant the term Animikie Series for middle Precambrian strata of the Northern Peninsula of Michigan and adjacent areas of Wisconsin. The Marquette Range Supergroup consists of the Chocolay, Menominee, Baraga, and Paint River Groups, as defined in previous literature. We feel that this new name to apply to Northern Peninsula rock units is appropriate, as continued investigations have failed to show unequivocal correlation between middle Precambrian rocks of Michigan and the Huronian Supergroup of Ontario. Although the equivalence of the Animikie Group in Ontario and Minnesota with parts of the Michigan rocks is likely, the Stratigraphic complexity of the Michigan sequence requires supergroup rank. The inherent confusion of an Animikie Group in Ontario and Minnesota, and an Animikie Supergroup in Michigan, makes a local name such as Marquette Range Supergroup preferable to Animikie for the middle Precambrian rocks of Michigan.

PALEOMAGNETIC EVIDENCE ON THE ORIGIN OF THE MARQUETTE AND STEEP ROCK HARD HEMATITE AND GOETHITE DEPOSITS

Hard hematite ore is mined at the Cliff-Shaft mine, Marquette Range, Michigan, and hard goethite ore is mined at the Caland and Steep Rock mines. Steep Rock Range, Ontario. A paleomagnetic study was made on 67 samples from the ore horizons and associated rocks of these deposits. Alternating-current demagnetization and other standard paleomagnetic procedures were used. Geologists have proposed several theories to explain the genesis of these iron deposits of direct-shipping grade. Both ore deposits have a prefolding remanence that differs in age from any of the associated rock units. This indicates that both deposits were formed as laterites resulting from the oxidation and leaching of primary iron formation by meteoric solutions. The hard hematite ore was derived from the primary magnetite-banded oxide facies of iron formation which underlies the ore at the Cliff-Shaft mine, and the hard goethite ore was derived from the primary pyrite facies at the Caland or Steep Rock mines. The laterites were subsequently buried, folded, faulted, and intruded, but the mineralogy, structure, and texture of the ores were essentially unchanged during these events.

A paleomagnetic study of concentrating iron ores from northern Michigan

Fifty samples were collected from the concentrating iron ores and associated rocks in northern Michigan, U.S.A. They came from: the Republic Mine, Marquette Range; the Groveland Mine, Felch Mountain District; and along the Menominee Range. Standard paleomagnetic procedures were used to study the samples. The Negaunee and Vulcan iron formations are thought to have been deposited as primary sediments of the hematite-banded and magnetite-banded oxide facies with chemical remanent magnetization (CRM) during the Middle Animikie. During dynamic or thermal metamorphism, the primary remanence directions were modified causing them to be rotated into the bedding plane to yield directions that are random in declination but which are uniformly distributed about the bedding plane in inclination. The metamorphism was likely associated with the Penokean orogeny during which the iron formations were tightly folded and then thermally metamorphosed. Paleomagnetism suggests that the iron formation at the Republic and Groveland Mines has been folded into synclines. The Lower Keweenawan diorites have a post-folding thermal remanent magnetization (TRM). The overlying Cambrian sandstones have a primary CRM or detrital remanent magnetization (DRM). The above paleomagnetic conclusions are consistent with the geologic evidence. The paleomagnetic pole position determined from the Keweenawan diorites and the Cambrian sandstones are thought to be fairly reliable.

Iron Agglomerates from the Marquette Range

With the gradual depletion of high grade iron ore reserves in the Great Lakes region much attention has been directed toward development of beneficiation techniques for the taconite ores of Minnesota. Last month Reserve Mining Co.’s new 3.75 million ton plant went into operation processing these ores, U. S. Steel has a smaller unit, and Erie Mining is building a mill. Less attention has been centered on the silicious ores of the Marquette Range, the so-called jasper ores. Many of the richer deposits are no longer producing, but there remains a vast reserve of non-magnetic specular hematite ore averaging some 39 pct Fe. In the past decade Cleveland-Cliffs has directed its attention to processing these ores into a concentrate suitable for blast furnace charging. The result of these efforts is now beginning to take shape.

Hydrothermal leaching of iron ores [Marquette range, Michigan

Hydrothermal leaching of iron ores [Marquette range, Michigan