Colloids in iron and ore sedimentation with special reference to a pisolitic hematite deposit on Black Island, Manitoba
Yarwood, Walter Samuel
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J.B.Tyrrell noted this occurrence of Manitoba iron ore. In his correlation the rocks of the southern portion of Black Island were placed as Cambro-Silurian in age. The sericite schists were regarded as being probably Huronian in age. Tyrrell noted the stalactitic nature of the hermatite. He did not attempt to arrive at a definite conclusion with regard to the origin of the deposit. Black Island in its relation to the surrounding country may best be realized from Fig. 1. The distance from the mouth of the Red River to Black Island is fifty-four miles. Black Island may be reached from Selkirk, or Victoria Beach by launch. The iron ore deposit in question is located on the east shore of Black Island, being a little north of west from the mouth of the Manigotagan River. The island lies on the contact between the Ordovician and Pre-Cambrian. The Ordovician commonly is at contact with the Pre-Cambrian. Between these horizons, however, there is a sandstone formation which has locally been named Winnipeg Sandstone. This does not generally exceed one hundred feet in thickness and is quite localised. The formation may be of the interrelated type similar to the St. Peter of the central United States. The southern part of Black Island approximating three-fourths in area of the total, is covered by this sandstone. Aside from the outcrops on the island the Winnipeg formation is seen in only one other area on the map as given. This occurs on the southwest corner of the peninsula separating the Manigotagan and Wanipigow River systems. There has been no deposition of limestone on the sandstone insofar as Black Island is concerned, thus the limestone is restricted to the west of the dotted line, Fig. 2. Subsequent to the Ordovician invasion there has been laid down a thin covering of glacial drift. The northern portion of Black Island consists of andesitic and trachytic lavas similar in every respect to the lavas bordering the Wanipigow River eastward....