| Summary: | The Hollaston Lake area is underlain by infracrustal rocks of
the Daly Lake Group which constitutes the major part of the Hollaston Lake
fold belt. Shape , greywacke , and arkose metamorphosed to the amphibolite facies of the Abukuma series form most of the. Group. In the Hollaston Lake
area, the Hidden Bay formation of the Daly Lake Group consists of feldspathic
quartzite and marble which occurs as layers bounded by calc-silicate rocks,
hornblende biotite rock, and biotite gneiss. Important mineral assemblages
in marble are: calcite-diopside-quartz; calcite-diopsioe-biotite:, calcitediopside-
idocrase; calcite-dolomite-forsterite-phlogopite: dolomite: calcitesCdPo:
Li i.:e-gtduui i.e+d i.op s i.de ; anci in ca.Lc-cs i Li ca t.e rOCKS are: dlopsldeplagioclase;
diopside-idocrase; and scapolite-grandite-epidote-quartz. The
rocks were metamorphosed to the middle to high amphibolite facies. Temperature
ranges were from 600 to 725 C and pressure from 2 - 6 kb. Marbles were derived from slightly dolomitic limestone. Calc-silicate rocks are the result
of metamorphic diffusion of CO2, and K20 from a calcareous-pelitic rock.
The movement of these components was probably caused by the incompatibility
of calcareous assemblages in the presence of mica-bearing assemblages at
the amphibolite facies. Diffusion and redistribution of Ca and Mg cations
within the calc-silicate rocks occurred to form large monomineralic segregations of diopside, plagioclase, tremolite, scapolite , and calcic+amphibole ,
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