ANT/MCL/06 ANTARCTIC

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Rebecca Chase
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1 ANT/MCL/06 ANTARCTIC

4 Chick Is [Island] 21/2/61 [21st February 1961] Rock is brn. [brown] charn. [charnockitic] granite, c.g. [course grained] comp [composed] of brn [brown] felsp [feldspar] & [and] py [pyroxene]. Felsp [Feldspar] has a poor foln [foliation] E [East] - W [West] (True) dip abt [about] vert [vertical]. Foln [Foliation] generally hard to see. Roughly cubic jointing, best one N [North] 60, V [Vertical (mag [magnetic]), 2-6 ft [feet] apart, another ft [feet] apart, and a widely spaced 20ft [foot] one near horizontal. Iced smoothed surfaces fairly common, but in many cases these are only remnants, the rest having exfoliated off. Incl [Inclusions] fairly common, most c [with] sharp edges. Size from < [less than] 1 inch to abt [about] 2 feet. Shape from roughly circular to elongate. Most elongate ones, usually only small, and parl [parallel] to foln [foliation]. Most common is fg [fine grained] granulite consisting of felsp [feldspar] & [and] py [pyroxene], some of 3

5 them very dark, others c [with] only a small amr [amount] of pyrox. [pyroxene]. Some of these granulitic ones are banded & [and] banding is not parl [parallel] to foln [foliation] of granite! Other types are: mg [medium grained] - cg [coarse grained] pink felsp [feldspar], qtz [quartz] & [and] hbde [hornblende], aplitic textured felsp [feldspar] & [and] qtz [quartz] c [with] some biot [biotite], peg [pegmatite] textured pink felsp [feldspar] & [and] qtz [quartz], mostly xls [crystals] an inch across, in one case c [with] a felsp [feldspar] x [crystal] 9" [inches] across. These felsp [feldspar] incl [inclusions] usually a couple of ft [feet] across. Rare pinhead size garnets occur in peg [pegmatite] & [and] apl [aplitic] type incl. [inclusions]. One apl [aplitic] incl [inclusion] is 10 ft [feet] long & [and] 1 ft [foot] wide, along foln [foliation] of granite. Other types are mineralog [mineralogically] like granite but finer grained - sim [similar] to gran [granite] in texture but less pyrox [pyroxene]. Some of former have a felsic rim ¼ [one quarter] inch wide. One large square incl [inclusion] abt [about] 10 ft [feet] across is fg [fine grained], gneissic, c [with] streaks of pyrox [pyroxene] in felsp [feldspar]. 5

6 In several places are single felsp [feldspar] crystals 3-4 ins [inches] across, usually rounded, & [and] brown. Could be either incl [inclusions] or phenocrysts. Not very common, and occ [occasionally] only as isolated xls [crystals]. (Photo [photograph] of incl [inclusion], & [and] spec [specimen] - granulitic type). 7

7 Henry Is [Islands] 22/2/61 [22nd February 1961] Rock is c [coarse] - mg [medium grained] biot [biotite] granite (spec [specimen]) somewhat porphyritic, c [with] slight alignment of big feldspars. Inclusions fairly common, most common being a f [fine] - mg [medium grained] biot [biotite] - felsp [feldspar] schist. Some equant c [with] fairly sharp corners, some rounded, some lenticular, all roughly aligned N [North] which is abt [about] same drn [direction] as foln [foliation]. All sharp edged. Also some small (up to 4" [inches] across patches of fg [fine grained] felsp [feldspar], pink, some c [with] flecks of biot [biotite]. Edges rather irreg [irregular], but sharp. Also roughly aligned parl [parallel] foln [foliation] of gran [granite]. Dark incl [inclusion] up to 1 ft [foot] across. Some dark incl [inclusions] c [with] rather vague edges, as though partly assim [assimilated]. 9

8 Several straight veins of fawn felsp [feldspar], parl [parallel] sided up to 6" [inches] wide. Some cg [coarse grained], c [with] tendency to cont. [contain] felsp [feldspar] phen [phenocrysts], others c [with] alaskitic texture, thin ones c [with] coarse same aplitic texture. Edges sharp. (Specs [specimens]). Also a couple of veins of biot, straight, fairly uniform width of conc [concentration] of mg [medium grained] biot [biotite] flakes. Usually a couple of inches wide. Edges fairly sharp. May represent v. [very] early joints. Some xens [xenoliths] (usually small) of biot [biotite] & [and] felsp [feldspar], c [with] granulitic texture & [and] no banding. Many of schist incl. [inclusions] espec [especially] larger, have good banding of biot [biotite] & [and] felsp [feldspar]. Lin. [Lineation] of phen [phenocrysts] on N [North] 160 [degrees]. Alignment of felsp. [feldspar] seems to be a lineation rather than a foln. [foliation]. Str. [Strike] N [North] 160 mag [magnetic] (= T [True]) Better devel. [developed] in some places than in others. 11

9 Some of the dark fg. [fine grained] incl. [inclusions] have mg [medium grained] felsp. [feldspar] porphyroblasts. Western most group of islets is sim. [similar] to main group, with sim. [similar] incl. [inclusions]. Lin: [lineation] of feldspars [feldspars] is less pronounced, & [and] cannot be seen in many places. Spec. [specimen] from largest is of this group of incl. [inclusions] for age det. [determination]. Several photos [photographs] of group from ground & [and] air. 13

10 14 Peak / Wilson Hills 5/3/61 [5th March 1961] see pocket Ht [Height] Biot [Biotite] sch [schist], f [fine] - mg [medium grained] c [with] thin 1/4" [ one quarter inch] bands of felsp. [feldspar], & [and] conc. [concordant] veins of qtz [quartz] & [and] felsp [feldspar] mg. [medium grained]. 2 Dykes of mg [medium grained] qtz [quartz] felsp [feldspar] & [and] biot [biotite] (spec [specimen] several ft [feet] wide, some c [with] small garn [garnet] clusters rimmed by biot. [biotite]. 3 Some bands of mass [massive] biot [biotite] felsp [feldspar] rock f [fine] - mg [medium grained] (spec [specimen]) 2 Some dykes cg [coarse grained] c [with] biot [biotite] in clusters 1-2" [inches] across, or in schlieren 4" [inches] long 1/2" [ half inch] wide. Also garn [garnet] c [with] biot [biotite] assoc [associated] but not rimming. 4 Cutting all are dykes of mass [massive] mg [medium grained] gran [granite], discord [discordant] & [and] concord [concordant] (spec [specimen]) sharp edges, straight, c [with] finer phases cutting them in turn.

11 1 Irreg [Irregular] fingers of cmg [coarse to medium grained] felsp [feldspar] qtz [quartz] biot [biotite] rock along schist, some felsp [feldspar] augen 1" [inch] across. Schl [schist] up to coup [couple] ft [feet] long, 6 " [inches] wide. 2 Dykes & [and] fingers of 1 prob [probably] same origin, diff [different] degrees. In places dykes form network (photo [photograph]) 1 In places, acid schlieren made up of felsp [feldspar] augen & [and] biot [biotite] feathers. 4 Spec [specimen] of fg [fine grained] last veining in schist. 5 Spec [specimen] of fg [fine grained] acid vein. Aneroid in saddle 2820 o/c [outcrop] 2780 Str [Strike] N [North] 30 [degrees] mag [magnetic] dip 80 [degrees] E [East] tight folds in places, small in others acid lenses sigmoidal. 15

12 6/3/61 [6th March 1961] Aviation Is. [Islands] Westernmost 1 Biot [biotite] felsp [feldspar] gn [gneiss] with ptygmatic veins & [and] num. [numerous] inj. [injections] of mg [medium grained] biot [biotite] gdior [granodiorite]. 2 Biot. [biotite] gdior [granodiorite] (specs [specimens]) mg [medium grained] equingran [equigranular]] mass. [massive] forms irreg. [irregular] bands up to several ft [feet] wide. Sharp edged, transgressive contacts, some straight others very irreg. [irregular]]. Cont. [contain] scattered felsp. [feldspar] phen. [phenocysts] thumbnail size. Lim (limonite) stained in spots. Some intr. [intruded] by thin veins of c [coarse] - mg [medium grained] felsp [feldspar] c [with] some biot [biotite], & [and] biot [biotite] lim selvedge. Also some irreg. [irregular] sim [similar] patches. In places phen. [phenocysts] form knots several " [inches] across. In places are irreg. [irregular] masses a few ft [feet] across of cg [coarse grained] felsp [feldspar] (white) & [and] scattered biot [biotite] c [with] local concs.[concentrations] of biot. [biotite]. Grain size rather irreg. [irregular]. 17

13 In places even the mg [medium grained] gran [granite] has local conc. [concentrations] of biot [biotite], often tightly folded (photo ]photograph] of this and gneiss). Proport. [proportion] of biot. [biotite] var. [varies] from vein to vein. Gneiss f [fine] - mg [medium grained] biot [biotite] felsp [feldspar], usually some fine banding, in places, biot [biotite] laminae pure biot [biotite] (photo [photograph]). Very tight contortions visible in places. Typical ptygmatic veins fairly common. Gn. [gneiss] cut through irreg [irregularly] by thin veins of mg [medium grained] gran. [granite] One transgressive lense lens like vein of fg [fine grained] felsp [feldspar] biot [biotite] rock (spec. [specimen]) sharp str. [straight] edges. Some of the coarse acid veins cont [contain]? zircon, many cont [contain] muscovite iron staining asoc. [association] c [with]? zircon. In many of the smaller veins, incl. [inclusions] are common of biot [biotite] gn [gneiss]. ( or apparent incl [inclusions] ) 19

14 Gneiss is folded but gen [generally] str [strike] appears to be N [North] 30 [degrees] E [East] mag [magnetic] dip [degrees] W [West]. Equiv [equivilant] bearing from ship N [North] 131 [degrees] true. On west side str [strike] poss [possibly] abt [about] N [North] 60. Some of the cg [coarse grained] gran [granite] veins cont [contain] crystals of? zircon fairly common in places (specs [specimens]). In another place, one cont [contained] fluorite? - or cordierite, since sillimanite is present in one piece. 21

15 Aviation Is [Islands] 6/3/61 [6th March 1961] Easternmost. Rock is porph [porphyritic] gran [granite] (spec. [specimen] A) mg [medium grained] - cg [coarse grained], c [with] good foln [foliation] of felsp [feldspar]. N [North] 50, 70 N [North] (mag [magnetic]). In places, biot [biotite] forms thin streaks through rock. A few cg [coarse grained] patches, feld [feldspar] c [with] biot [biotite] & [and] brn [brown] mica. Small clusters of pin head garnet (red) in a few places. A dyke, 5 ft [feet] wide, cutting across foln [foliation] of gran [granite] (spec [specimen] B ), of mg [medium grained] dior [diorite], sharp edges, fairly straight. Also several thin dykes up to 1 ft [foot] wide of f [fine] - mg [medium grained] dior [diorite] (spec [specimen] D) str [straight], sharp edged, parl [parallel] sided some c [with] a lighter selvedge several same width as dyke. Several incl [inclusions] in gran [granite], round, sharp edged, of dark fg [fine grained] 23

16 rock, prob [probably] biot [biotite] & [and] felsp [feldspar], & [and] c [with] lath like felsp [feldspar] porphyroblasts up to 1" [inch] long. A vein of iron stained qtz [quartz] (spec [specimen] C) In centre of island in gap, is banded gn [gneiss] like that on first island, forming band abt [about] 50 ft [feet] thick. Darker coloured, c [with] banding fairly prom [prominent]. Did not appear to be greatly intruded by granite. In part of it was an iron stained band, several feet wide. Texture of granite is slightly variable, but general appear [appearance] is same all over. Biot [Biotite] content varies slightly. 25

17 . 6/3/61 [6th March 1961] Aviation Islands Islands between easternmost and westernmost are biot [biotite] gn [gneiss] like western one. Granite veining is less prominent (apparently). On island second from east strike appears to be N [North] 50 (mag [magnetic]) dip 70 [degrees] N [North]. Jointing is much more apparent than on westernmost is [island], esp [especially] jointing parl [parallel] to foln. [foliation], and also vert [vertical] jts [joints] normal to foln [foliation]. On western is [island] jts [joints] are fairly widely spaced although in places rock is split parl [parallel] to foln [foliation]. 27

18 28 Main Aviation Is [Island] 298 [degrees] mag [magnetic] Str [strike] 200.

19 wpeak 2 Mainly garnet, gran [granite] gn [gneiss] irreg [irregular] textured. Most common is little coarser than sugary c [with] felsp [feldspar] qtz [quartz] biot [biotite] & [and] red - brn [brown] garn [garnet] (spec. [specimen] 1) Poor foln [foliation]. Garnet commonly in ¼ " [one quarter inch] clusters. Garn [garnet] almost absent from some parts, esp [especially] somewhat finer gn [gneiss]. [?] mg [medium grained] rock are coarser (spec.[specimen] 2 swapped) patches several ins [inches] across, felsp [feldspar], (fawn) some qtz [quartz], garn [garnet] & [and] big biot [biotite] (1" [inch]).tendency for garn [garnet] to be more common in these. In granite are remnants of banded gns [gneiss] commonly several ft [feet] wide. Gran [granite] veins cut them if, sharp edged f [fine] - mg [medium grained]. Also cutting everything are pegs [pegmatites] a few ins [inches] wide, straight, parl [parallel] sided, commonly zoned, felsp [feldspar] c [with] sericite 29

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21 down centre, scattered red brn [brown] garn [garnet], biot [biotite] not common. Felsp [feldspar] is perthitic, creamy. Little qtz [quartz]. Also thin 1/8" [one eighth inch] long straight felsp [feldspar] veinlets. Gneiss is f [fine] - mg [medium grained] biot [biotite] felsp [feldspar], usually banded c [with] thin 1/16 [one sixteenth] - 1/8" [one eighth] [inch] bands, close spaced. Small scattered clusters of pink garn [garnet], pea sized, fg [fine grained] xls [crystals], best seen on weathered surfaces. Sim [similar] sized clusters of fg. [fine grained] biot [biotite]. Mg [medium grained] gran [granite] veins cut thru [through] this, usually parl [parallel] to banding. In places gneiss is irreg [irregular] invaded by masses of qtz [quartz] & [and] felsp [feldspar], some fg [fine grained] massive, others varying up to vcg [very coarse grained]. In places veining is so dominant that only irreg [irregular] remnants of gneiss left. Most of those have a striated out look. In places are mg [medium grained] - cg [coarse grained] small masses of biot [biotite] and / or garnet. 31

22 32 Apl [aplite] vein blue qtz [quartz] veins.

23 Gneiss commonly strongly plicated. General str [strike] appears abt [about] N [North] 200, (mag [magnetic]) dip west bet [between] However prob [probably] many folds. 20' [feet] south of northern low peak is a basalt dyke, 3' [feet] wide str [strike] 40 [degrees] mag [magnetic], prob [probably] vert [vertical]. Vesicular, well jtd [jointed], and weathered choc. [chocolate] brn [brown] on outer surface of pieces, (spec [specimen]) Spec [specimen] of contents from float lower down. Another type of ig [igneous] rock is f [fine] - mg [medium grained]? dior [diorite] cutting across mg [medium grained] garn [garnet] gran [granite] c [with] remnants of gneiss streaks. Edge fairly sharp c [with] parl [parallel] banding, but not knife edge. Str [strike] abt [about] 310 [degrees] mag [magnetic]. Abt [about] 20 ft [feet] wide (Spec [specimen] 4) Another parl [parallel] lower down 33

24 34 pk [peak] 2 terrace 650 Ht [height] 2000 pk [peak] 3 end 460 Ht [height] 2000, Apl. [aplite] on 2 pk. [peak] 3 str [strike] N [North] 30 mag [magnetic] dip [degrees] E [East] mag [magnetic] folded

25 Peak 3. Sim [similar] to Peak 2, biot [biotite] gn [gneiss] biot [biotite] gneiss in [?] [?]. (Spec. [specimens]). Much less veining, great stretches of gn [gneiss] c [with] out veins. Veins are fg [fine grained] aplite - rare. mg [medium grained] garn [garn] gran [granite] c [with] little biot [biotite], & [and] in places, few garnets. Some felsp [feldspar] veins in places, ig [igneous] rock is common as veins 1/2 [half] - 1" [inch] thick along foln [foliation] of gn [gneiss] locally. Some veins of felsp [feldspar]! Rocks appear to be tightly folded in folds several ft [feet] across. From air, a net of broad pink veins seen on east side of peak. Peak to the west of Peak 3. At NE [North East] corner of peak east of Peak 3, scree near base 35

26 is pinkish colour. Rest of scree is chocolate coloured. Mts [mountains] bet [between] Williamson Head & [and] Tomlin[Tomilin] Glac [Glacier] (at east) show evidence of faults parl [parallel] to coast. Two and in places 3 levels of summits can be seen. 37

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28 . Index. Page Subject. 3 Chick Is. [Island] 9 Henry Is. [Island] 14 Peak Aviation Is. [Islands] westernmost 23 Aviation Is. [Islands] easternmost 27 Aviation Is. [Islands] - general 29 Peak 2 35 Peak 3

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Hand specimen descriptions of metamorphic rocks

Hand specimen descriptions of metamorphic rocks Hand specimen descriptions for metamorphic rocks are like those for igneous rocks. The objective is to tell someone looking at it everything they need to