92

igneous-appearing material is greatest at the southwest end of the belt of
exposed Wolverine complex rocks, where two stocks of granodiorite, about
$ square mile and 5 square miles in area, respectively, are surrounded by a
swarm of sills, dykes, and irregular bodies of leucogranite, pegmatite, aplite,
graphic granite, and alaskite. Dykes and stocks are smaller and fewer
toward the northeast, and are rare between Ravenal Creek and Tomias
Lake; still farther east, and on the crest of Butler Range, they are more
abundant.

Feldspathic Quartzite

The common, generally well-bedded, slightly impure quartzites of
the Ingenika and Tenakihi group rocks are represented in the Wolverine
complex by light grey to golden brown, granular rocks composed of various
proportions of quartz, feldspar, biotite, and, rarely, muscovite. The
weathered surface of these rocks has a distinct speckled appearance due to
the white, opaque coating on weathered feldspars. This type of weathering
appears to be more or less unique to the rocks of the Wolverine complex
jn the area, and was not observed on the less metamorphosed feldspathic
sediments of the Tenakihi and Ingenika groups. All such rocks are
schistose or gneissic, with the plane of schistosity or gneissosity in all
observed cases rigorously parallel with the bedding planes, which are for
the most part conspicuously outlined by bands of different biotite content.

In general, these rocks are of somewhat coarser texture than their
equivalent beds in the normal Ingenika and Tenakihi groups; most of them
are even-granular, with grains up to 1 mm. in average diameter. A few
rocks are markedly porphyroblastic, with irregular porphyroblasts of either
quartz, feldspar, or biotite up to 5 mm. in diameter.

The quartzites have a wide range of composition, both from bed to
bed and within the same bed, due mainly to a varying amount of material
added from extraneous sources, and to a reciprocal transfer of matter from
bed to bed. In some beds, original differences in the chemical and minera-
logical makeup have been emphasized, in others, nearly obliterated. Almost
all of the quartzites observed within the Wolverine complex are feldspathic.
It is not known whether any of these rocks were originally representatives
of the extremely pure quartzites found in the Ingenika group. In several
places the conglomeratic phases of the Ingenika group can be recognized
within the Wolverine complex, with the original pebbles represented by
clots of quartz or quartz and feldspar. The rocks grade, by decreasing
quartz content, into quartz-mica-feldspar schists. The feldspar content
varies considerably, being generally between 10 and 60 per cent of the
rock volume. A rough relation is apparent between the degree of recrystal-
lization and the amount of feldspar; in general the most highly metamor-
phosed rocks are the most feldspathic. There is much change of feldspar
content within distances of several hundred feet in the same bed. With
increasing intensity of recrystallization and reconstitution, the feldspathic
quartzites grade into quartz-mica-feldspar gneisses and migmatites.

In thin section all the feldspathic quartzites have a completely crystal-
loblastic texture. Some of the quartzites reveal the effects of crushing,
with consequent granulation and recrystallization of fine fragments
between larger grains, producing ‘mortar structure’.