Department of Earth Sciences, University of New Brunswick, SEG Student Chapter: Nova Scotia Field Trip Report

(June 17th – 19th, 2016)

The Society of Economic Geology student chapter at the University of New Brunswick

conducted a three-day field trip to Nova Scotia, Canada in June 2016. The rationale of

choosing Nova Scotia is the fact that its geology records a history of over a billion years

that includes the formation of the Appalachian Mountains and the opening of the Atlantic

Ocean. As a result, it hosts numerous intrusion-related and vein style mineral deposits.

The main goal of this field trip was to visit some of these deposits along with other areas

of metamorphic, igneous, structural and sedimentary geology interests. Below is a short

summary of the sites we visited in this trip.

Day 1: The first day was primarily devoted to driving into the province, with several

short stops along the way to understand the vast and diverse geologic history of the

province. There were three stops on the first day, all three of which were in the Cobequid

Highlands of Nova Scotia.

First stop: Wharton, Nova Scotia

Highway 209 of Nova Scotia runs along the Cobequid-Chedabucto fault system for a

segment of the western end of the fault. This fault is of economic interest due to the

abundant iron oxide-copper-gold mineralization along the fault. The famous Londonderry

iron deposits are a result of fault-related hydrothermal alteration. The first stop of the day

was at a phyllite roadside outcrop along the Cobequid-Chedabucto fault. This phyllite

belongs to the Jeffers Group which is likely part of the Meguma terrane, a peri-

Gondwanan domain. Because the fault experienced multiple episodes of movement, the

exact age of these phyllites is unknown. Drag folds at this location give a sense of shear

of the fault, and siderite-bearing veins related to the iron-mineralization along the fault

were also observed at this outcrop.

Figure 1. (a) Drag folds indicating a sinistral movement along the fault. (b) Photo of siderite-bearing

veins related to iron oxide-copper-gold deposits along the fault. (c) Photo of outcrop with the drag folds

from photo 1(a) to the left of the group.

Second Stop: Five Islands Provincial Park, Nova Scotia

The second stop of the day was at Five Islands Provincial Park which is located on the

northern shore of the Bay of Fundy. While this stop is not of economic interest, it is of

importance in understanding the geologic history of Nova Scotia. At this stop we

observed red sandstone cliffs of the McCoy Brook Formation carved out by the highest

tides in the world. In faulted contact with the sandstone is basalt from the North

Mountain Formation. Both were deposited in the Jurassic during early failed rifting of the

supercontinent Pangea. Cross bedding was observed in the sandstone as well as

interlayered mudstone and siltstone which give the cliff face a dramatic striped

appearance. Fault gauge and breccia were identified between the sandstone and basalt.

a b

c

Within the basalt unit, amygdules were observed representing the tops of the flows and

beautiful columnar jointing was observed in the middle part of the flow.

Figure 2. (a) Interlayered beds of siltstone (red) and mudstone (grey). (b) Cross-bedding in conglomerate

and sandstone. (c) Fault breccia with basalt clasts. (d) Columnar jointing in basalt flow with red sandstone

and overlying basalt further down the beach.

Third Stop: Economy River Falls, Nova Scotia

The third and final stop of the day was at the Economy River Falls where we observed

the Proterozoic orthogneiss of the Economy River Gneiss. These are some of the oldest

rocks in the province and zircon grains give an age of 734 Ma. Also observed at this stop

were amphibolite and syenogranite that intruded the gneiss. Along the river at the base of

the falls are occasional boulders of magnetic ironstone that predates the orthogneiss and

formed in a pull-apart basin during the breakup of Rodinia.

a b

c d

Figure 3. (a) Outcrop photo of Economy River Falls. (b) Hand sample photo of Economy River

Orthogneiss with banding parallel to the pen.

Days 2 & 3: The second day was spent in and around Yarmouth County visiting various

historic and current deposits.

LCT Pegmatite Deposit (Brazil Lake Area)

The Brazil Lake pegmatite deposit carries the major economic geology part of our field

trip to Nova Scotia. These rare-element pegmatites are important resources for economic

concentrations of rare elements (e.g. Sn, Li, Ta, Rb, Cs, etc.), presence of high-quality

industrial minerals (e.g. muscovite, spodumene, feldspar, Fig 1a), and occurrence of gem

minerals (e.g. tourmaline, beryl Fig. 1b) and they are often related petrogenetically to

fertile, progenitor granites. This is an active exploration site that intends to launch

another drilling phase of about 1660 meters on the property this summer (personal

communication with John Wightman, the exploration geologist during site visit).

Metallurgical work conducted on a 272 kg sample of spodumene-rich (34.4%

modally) pegmatite indicated 0.18-0.3 wt. % Fe2O3 in the spodumene. Shell Canada Ltd.

evaluated the site with mapping, geophysics and geochemical sampling, and found

variable, but elevated levels of Li (<275 ppm), Rb (<190 ppm), Cs (<100 ppm), Sn (<177

ppm) and Ta (<95 ppm). A more extensive program of drilling and stripping in 2002 by

Champlain Resources Inc. exposed a large area of previously unknown pegmatite. Work

a b

to date indicates that this pegmatite has the potential to produce high-quality feldspar,

quartz, mica and spodumene with appreciable grades of tantalum.

Figure 4: Spodumene-rich boulder (a) from Kspar-

muscovite-quartz-spodumene dyke, b) beryl crystals

cropping out of the quartz-Kspar- pegmatite dyke at

the Brazil Lake area, and c) Dr. Geoff from Nova

Scotia Department of Natural Resources explaining

regional geology to the SEG students members of

the group.

Kemptville Gold/Molybdenum Project

This field trip also visited the historic Kemptville Gold District. In this area we observed

floats of high grade to very high grade (up to 300g/t) disseminated gold hosted by

pervasively sericitized and variably silicified greywacke. These float boulders are located

in an area between the former Kempt and Cowan gold mines in the historic Kemptville

Gold District and had been located by AYARCO Gold Corporation (Ltd) in their

previous work in the area. Efforts have been made to locate the source of the float using

several exploration methods including ground magnetometer and VLF-EM surveys, MMI

soil surveys, gold in till analysis, fabric analysis, and diamond drilling. Although gold

values of up to 5g/t were intersected in altered greywacke, the intense sericite

a b

c

Beryl

Spodumene

development and silicification seen in the high grade material found at surface was not

seen in any of the drilling done to date (AYARCO Gold Corporation Ltd, Report). More

drilling is expected this summer to further try to locate the source.

Figure 5: a) and b) are photographs of floats of high grade to very high grade (up to 300 g/t) disseminated

gold. Reddish-brown color represents the surface weathering and oxidation of sulphides.

White Rock Mine (quartz and kaolin deposits) white or Bob

This mine is owned by Black Bull Resources Inc. The company reports that it has defined

a high-quality quartz (silica) deposit with total measured plus indicated quartz resources

of 12.2 million tonnes, grading 97.4% SiO2, with an additional inferred quartz resource of

7.3 million tonnes. This is one of the largest white quartz deposits in eastern North

America. Black Bull has also reported that the quartz ore can be upgraded to 99.5% SiO2

with flotation processing, which could allow for additional value-added applications of

the material. Unlike many quartz deposits, which consist of quartz-rich sedimentary sand

(silica sand), the White Rock Mine is a primary hydrothermal bedrock deposit. The

deposit lies within the Tobeatic Fault Zone along the southern margin of the South

Mountain Batholith, a large granite body. The ore zone consists of a massive quartz

breccia core, generally 50-100 m wide, which is flanked by quartz-kaolin-mica breccia

zones ranging in width from 10 to 60 m. This massive, high-purity quartz core will allow

Black Bull Resources to provide its customers with a wide range of particle sizes, from

very fine grains up to approximately 15 cm in diameter. To date the deposit has been

a b

traced along strike for 2 km and is open to the southwest, with excellent potential for

additional resources.

Figure 6: A group photo standing on one of the white rock (kaolinite and quartz) pile (a); and a close-up

photo of the quartz crystals with interstitial kaolinite (b)

Ovens Gold Mine (Ovens area)

In this area, we visited and saw weakly metamorphosed turbidite deposits of the lower

Halifax Group, which is dominated by slate and metasandstone metamorphosed to lower

greenschist facies with cross-cutting quartz veins. This represents one of the first gold

mines in the Lunenburg County, Nova Scotia. It was developed during the first gold rush

between 1861 and 1874 and therefore will be an exploration of historic gold mining sites

along the Sea Cave Trail.

The Ovens district occurs in the hinge of a tight (inter limb angle 35 - 50°)

regional anticlinal structure, one of several northeast-trending fold structures of box- and

chevron style in the region (Fig. 7a). The area contains an abundance of quartz veins (Fig.

7b), which importantly are mostly concentrated in the hinge area of the fold (Fig. 7a).

Veins types include both bedding parallel and discordant varieties, with the former

including veins variably described as bedding-concordant, saddle-reef and buckled vein

types. As noted by Horne and Culshaw (2001), the orientation of the veins, kinematic

indicators, mutually cross-cutting relationships of veins and similar accessory mineralogy

of all vein types (gold, scheelite, Fe–As sulphides) suggest emplacement of all vein types

during late-stage tightening of an existing fold structure by a flexural-slip fold

mechanism.

Figure 7: Simplified geology of the Ovens area

which is located in the hinge of a northeast-trending

anticline (a); gold-bearing quartz veins (b); and an

underground mining audit of the past (c).

c

Peggy’s Cove Area

The last stop of our field trip ended up by visiting the Peggy’s Cove area of southern

Nova Scotia which contains abundant, flat-lying, zoned, tourmaline-bearing aplite–

pegmatite sheets cutting leucomonzogranite of the peraluminous, 372 Ma South

Mountain Batholith (Fig. 8a). This holocrystalline, coarse-grained granite is dominated

by potassium feldspar typically appearing as large, rectangular crystals in a fine-grained

matrix, plagioclase, quartz, and biotite (up to 10%) with rapakivi texture in some places

(Fig. 8b). Cutting across some outcrops are narrow tourmaline-bearing aplite–pegmatite

sheets (Fig. 1A). They contain minerals similar to those in the granite. Aplite has a fine-

grained, sugary texture and lacks biotite (Fig 8f), while in pegmatite the crystals are

unusually large (Fig 8e). Tourmaline occurs within the aplite–pegmatite sheets as coarse

rosettes of euhedral crystals within aplite (Fig. 8f), and segregations or pods of

tourmaline within zoned pegmatites (Fig. 8e); these pods, with maximum dimensions of

10–30 cm, contain the largest concentration of tourmaline.

In some locations there are fragments of dark grey rock surrounded by granite. These

are bits of the rock into which the granite intruded i.e., Meguma’s metamorphosed

sedimentary rocks (Fig. 8c; Barr and Hild, 2015).

Figure 8: Field observation of Peggy’s Cove Granite in Nova Scotia: a) Extensive outcrop of Peggy’s Cove

granite with aplitic sheets. b) Rapakivi texture in coarse-grained Peggy’s Cove granite. c) Dark grey

xenoliths in different sizes in the granite (Meguma’s metamorphosed sedimentary rocks). d) Ronald

explaining the difference between xenolith and an enclave for the group. e) Rosette tourmaline in very

coarse-grained pegmatite. f) Rosset tourmaline in fine-grained sugary textured aplite.

References

Barr, S., & Hild M.H., 2015: Geology of Nova Scotia: Field Tip Guide Book.

Doig, R., Murphy, J. B., & Nance, R. D. (1993). Tectonic significance of the Late Proterozoic Economy

River Gneiss, Cobequid Highlands, Avalon composite terrane, Nova Scotia. Canadian Journal of Earth

Sciences, 30(3), 474-479.

Horne RJ, Culshaw N (2001) Flexural-slip folding in the Meguma Group, Nova Scotia. J Structural

Geology, 23:1631–1652.

Hickman Hild, M., Barr, S. M. (2015). Geology of Nova Scotia. Boulder Publications.

Nova Scotia Department of Natural Resources (2016, February 19). Geological Map of the Province of

Nova Scotia. Retrieved June 16, 2016, from

http://novascotia.ca/natr/meb/download/mg/map/htm/map_2000-001.asp

Pe-Piper, G., Reynolds, P. H., Nearing, J., & Piper, D. J. (2004). Early Carboniferous deformation and

mineralization in the Cobequid shear zone, Nova Scotia: an 40Ar/39Ar geochronology study. Canadian

Journal of Earth Sciences, 41(12), 1425-1436.

Tanner, L. H. (1994). Distribution and origin of clay minerals in the lower Jurassic McCoy Brook

formation, Minas Basin, Nova Scotia. Sedimentary Geology, 92 (3-4), 229-239.