. The copper-bearing rocks of lake Superior / by Roland Duer Irving. Geology; Geology; Copper ores; Copper ores. INNER TRAP BELT OF THE PORCUPINES. 215 with few or many porpliyritic feldspars. The thin sections show this rock in some cases as a typical ashbed-diabase, with a few porphyritic orthoclases, and in others as a true diabase-porphyrite. The latter presents very numerous porphyritic orthoclases in an excessively fine base, in which there are portions which polarize only very feebly or not at all, and in which minute tabular plagioclases with rare augite, magnetite and ferrite particle
. The copper-bearing rocks of lake Superior / by Roland Duer Irving. Geology; Geology; Copper ores; Copper ores. INNER TRAP BELT OF THE PORCUPINES. 215 with few or many porpliyritic feldspars. The thin sections show this rock in some cases as a typical ashbed-diabase, with a few porphyritic orthoclases, and in others as a true diabase-porphyrite. The latter presents very numerous porphyritic orthoclases in an excessively fine base, in which there are portions which polarize only very feebly or not at all, and in which minute tabular plagioclases with rare augite, magnetite and ferrite particles are the only recognizable ingredients. Some of the beds are of the ordinary type of fine-grained diabase, and the amygdaloids present no unusual characters. The rocks of this belt can be seen to best advantage on the upper Carp River, in sections 19 and 30, T. 51, R 42 W.; on the road from Union mine to Carp Lake, in Sec. 24, T. 51, R. 43. W.; along the course of the stream south from the same road in the NE. ^, Sec. 23, T. 51, R. 43 W.; in the NW. i of the same section along the larger stream which runs into Carp Lake near its southeast corner; and on the Little Carp River in sections 17 and 20, T. 50, R. 44 W. On the upper Carp the junction with the overlying conglomerate is seen at 450 paces north and 1,630 west of the southeast corner of Sec. 19, T. 51, R. 43 W., where the strike is northwest, and the dip north- east 25°. Hence up stream to the junction with the in- cluded conglomerate at 282 paces north and 1,630 west of the same corner the ex- posures are nearly continu- ous and show much of the fine-grained reddish mela- phyr, besides several bands of amygdaloid and diabase of . â,,.â â Fig. 4.âMap of exposures ou upper Carp Eiver, Porcupine the Ordmary types, i he thick- Mountains, one inch = 90 paces. ness between the two conglomerates is about 200 feet. The upward course of the stream follows the junction with the lower conglomerate to a point. Soiiih. Zgyate
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Keywords: ., bookcentury1800, bookdecade1880, booksubjectgeology, bookyear1883
