FIELD TRIP PHOTOS OF METAMORPHIC ROCKS OF GRAND MANAN
This series of photos was taken by me (Greg McHone) as a participant on the field trip led by Leslie Fyffe and Richard Grant, one of many trips organized for the 2001 New England Intercollegiate Geological Field Conference (NEIGC), held September 21, 22, and 23 and hosted by the University of New Brunswick. Copies of the field trip guidebook for this conference are available from the Department of Geology, University of New Brunswick, Fredericton, NB E3B 5A3, Canada. Phone 506-453-4803 or email email@example.com.
The trip was held on Grand Manan Island on Friday, September 21, 2001, on a cloudy, cool day. There were nine field stops, which are described in more detail in their guide paper, Precambrian and Paleozoic Geology of Grand Manan Island: The Ganderian Margin of Iapetus (linked to a scanned PDF file on this website, posted by permission of Les Fyffe and Dick Grant). Refer to that paper for details and directions to the sites as well. Although the trip stops were not actually visited in numerical sequence during the trip (because of tide considerations), they are posted in the order of the field guide paper.
Les Fyffe started the field trip with a general overview of Grand Manan geology, assisted with map holding by Nancy McHone. The open-file geological map of Grand Manan had recently been published by the New Brunswick Dept. of Natural Resources and Energy, Minerals and Energy Division, Plate 2000-29 (revised 2001). The Mesozoic section (western 2/3 of the island) is still being mapped by Greg McHone and has little detail on the map. The road map from Fyffe and Grant's field guide, showing approximate locations of stops 1 through 9 (north to south). Field stops 2-4 were in private front yards (it will be obvious when you get close), so be sure to get permission from the land owners if you wish to visit. Exact directions with mileage are in the field guide.
My suggestion is actually to start a bit farther north, at Swallowtail Head. Walk out past the lighthouse to see the ancient meta-basalts of this point (Silurian? Castalia Group).
Then on your way back to North Head village, turn into Pettes Cove beach to see some schists and phyllites of the Cambrian? Castalia Group. These are faulted against the meta-basalts at the northern end of the beach, with some bands of barite in what might be a Mesozoic fault.
Stop 1 (Stanley Beach) shows the Cambrian Flagg Cove formation, which includes quartzite beds and gray-green phyllite (meta-shale), and a cataclastic granite layer (photo). At Stop 2 (The Dock), the Cambrian Great Duck Island formation has maroon-colored conglomerate interstratified with green to maroon meta-siltstone, which Les is describing. Stop 3 in Castalia (near the ball field) shows grayish-green volcaniclastic meta-sandstone of the Silurian (?) Priest Cove formation. At Ragged Point (Stop 4) the Priest Cove formation shows layers of metamorphosed felsic and mafic tuff (volcanic ash) with well-developed cleavage planes. The Thoroughfare (Stop 5) has massive white quartzite of The Thoroughfare formation (a member of the Cambrian Grand Manan Group, which includes the Flagg Cove and Great Duck Island formations). Stop 6 at Ox Head has meta-volcanic breccias mixed with maroon tuffs of the Late Proterozoic Ingalls Head formation. Stop 7 (Long Pond), probably part of the Priest Cove formation, shows a meta-volcanic flow with large spherules cored with quartz. Dick Grant welcomed J. B. Thompson, up from Harvard University with Mark Van Baalen to join the tour a bit late. Prof. Thompson is widely celebrated as the "Dean" of New England geology and metamorphic petrology. Stop 8 at Long Pond Bay shows sandstones, siltstones, and volcanic rocks (metamorphosed) of the Silurian (?) Long Pond Bay formation, along with volcanic breccias farther up the shore Still at Stop 8, there are spectacular laminated and crenulated-cleavage fabrics in the meta-volcanic siltstones and phyllites. Stop 9 is at the famous Red Point, where meta-siltstones and phyllites of the Long Pond Bay formation are highly compressed and deformed. This tightly-folded vein is part of several foliations present. Also at Stop 9 is the Red Point fault, where Early Jurassic North Mountain Basalt has slid down against red phyllite of the the Long Pond Bay formation. The basalt is both folded and brecciated.