PINGUALUIT IMPACT CRATER
- Air & Space Magazine Article
- Overflight of the Pingualuit Impact Crater in my Cessna C177B – C-GOZM (GOZooM)
- 00:00: La Moinerie Impact Crater;
- 01:50: Kuujjuaq, Quebec;
- 05:15 – 15:15: Overflight of the Pingualuit Crater;
- 18:00: Saglouc Fjord;
- 18:15: Salluit landing.
This is a “thumbnail” of an original LIFE Magazine article, August 1950, which documents the first report of Dr. Meen’s exploration of the Pingualuit Crater. To read the full article, scroll to the bottom of this page for the “large” image of the article.
In Northern Quebec, Canada, there is a pristine simple crater that in 1999 was renamed the Pingualuit Meteorite Crater. It is visible as the small circular structure in the mid-right side of this image, and is larger than the smallest crater on the moon that is visible by telescope from earth. The crater is 3.44 km in diameter with a depth of 400 metres. The lake which occupies the crater is 267 metres deep and it is Quebec’s deepest lake. The crater rim is over 100 metres above the surface of the enclosed lake with a pitch of 40 to 45 degrees down to the water. Uplift from the original impact extends outward to a distance equal to almost twice the diameter of the crater.General Area: North of the tree-line in an area of subdued topography in the Canadian Shield. The target rocks are crystalline and some bedrock structure is visible in the north. The area has been glaciated.
Specific Features: New Quebec crater is filled by an almost perfectly circular 3 km diameter lake which contrasts sharply with the irregular lakes of the area. Although glaciated, this relatively young structure retains an upraised rim and is surrounded by a faint zone of deformation extending 3 km from the rim. This may be best viewed at low sun angles. The lake has no exterior drainage. This closed system has developed its own local ecosystem, including fish with very large heads, which have adapted to minimal food sources. An intriguing question is how the fish got into the crater lake.
The first expedition to the crater was initiated by a prospector, Frederick W. Chubb, who thought the circular structure was a kimberlite tube and thus a source of diamonds. Victor B. Meen, from the Royal Ontario Museum of Geology and Mineralogy in Toronto, accompanied Chubb on the expedition. During the short preliminary investigation no meteorites (or diamonds) were found among the boulders on the rim or on the surrounding plain. Nevertheless, Dr. Meen felt quite certain that the morphology of the formation indicated that it was caused by the impact of a huge meteorite and not from volcanic action. Dr. Meen estimated that since there were no Inuit legends about the structure, the impact of the meteorite must have occurred at least 3,000 years ago. He named it Chubb Crater after the sharp-eyed prospector.
|The following newspaper article was published shortly after Dr. Meen explored and documented the geology of the Chubb, later renamed Pingualuit, Crater.
Dr. Meen returned the following year in an expedition sponsored by the National Geographic Society. During that return trip he discovered a magnetic anomaly on the crater rim that he thought was due to the signature of the meteorite. This hypothesis has since been proven wrong. It is now known that the majority of the mass of a large meteorite that contacts the earth at cosmic velocity will vaporize upon impact. The resulting explosion will form a circular impact crater in the target bedrock.
In the late 1950’s I saw Dr. Meen on our old black and white TV when he appeared on a CBC television program describing his expedition to the then named Chubb Crater. It fascinated me when he explained the concept that there are many impact craters still recognizable on our planet and I vowed that someday I would visit this crater specifically and possibly the others he mentioned! The Pingualuit Crater is of special importance because its discovery and identification as an impact crater gave rise to the identification of 26 authenticated impact craters/structures on the Canadian Shield (Grieve, 1991).
Up until 1962, the Pingualuit Meteorite Crater was classified as “only a possible impact crater” based on its morphology. Then Ken Currie, of the Geological Survey of Canada (GAC), found impactites on the raised rim of the crater (at the closest part of the rim in this image). From this discovery, Pingualuit was reclassified as a “probable” impact site. In 1988, Blyth Robertson, also of the GAC, found other deposits of impactites along the south coast of Lac Laflamme (visible in the background to the north in this image). These impactites were transported there by glaciation. The discovery and analysis of these impact melt samples firmly established an impact origin for the Pingualuit Meteorite Crater.
The impact melt rocks correspond to a chemical mixture of some of the local target rocks. They contained mineral and lithic clasts, some of which showed diagnostic shock-produced Planar Deformation Features in quartz. They also contain enrichments in Ir, Ni, Co and Cr suggesting that the impacting body was chondritic in composition with siderophile element enrichment (Grieve 1991). The exposed bedrock of the Pingualuit Meteorite Crater’s target rock consists of a mélange of metamorphosed, Archean plutonic rocks cut by rare basic dykes (Shoemaker, 1962).The 40Ar-39Ar dating method of the impact melt rocks determined the age of the impact to be 1.4 million years. This places the impact before the first major northern hemisphere continental glaciation in the middle Pleistocene (Grieve 1991). A detailed study of the petrography of the impact melt samples I-86 and II-88 from the Pingualuit Meteorite Crater illustrated the degrees of shock metamorphism affecting the accessory minerals: apatite, sphene, magnetitie and zircon (Marvin 1992).
Bouguer Anomaly gravity studies reveal a profile with a well-defined negative anomaly that is symmetrical with the crater. As was found in the gravity investigations of the Brent, Holleford and Barringer meteorite craters, the negative anomaly field is most likely the expression of low-density fragmental material underlying the crater floor. These craters all produce negative gravity fields due to the low density fragmental rock underlying them and the expanded crustal rocks forming their rims (Innes 1964).
Aerial Exploration – August 2001
My dream to visit this crater finally came true with first a trip in my airplane, GOZooM, over the crater followed by a ground expedition a few years later.
On the aerial trip over the Pingualuit Crater, I was accompanied by Mr. Terry Peters, a personal friend and flying instructor. A flight to that remote area of the Quebec Arctic is not a trivial expedition and Terry’s flying expertise was very welcome. The distance to the crater from Kuujjuaq (formerly Fort Chimo), our only reliable source of fuel in that area, demanded that I make exact calculations of fuel burn, fuel load and payload to ensure a safe flight between available airports. The weather also has to be factored into the planning to ensure a safe flight. Only by carrying extra fuel on board were we able to spend less than 20 minutes orbiting the Pingualuit Impact Crater and safely make it to one of the remote airports in the area (see below for Terry Peters’ description of our flight over the crater).
When we initially approached the Pingualuit Crater on my aerial exploration, the structure first appeared as a small hill on the horizon. We were forced to descend to an altitude of 1500 feet above the ground to keep under the cloud layer. When we arrived at the vicinity of the crater, the height of the rim and the depth of the crater were exemplified when the lake that filled the crater suddenly became visible from behind the crater rim only when we were about a kilometer away! What a view! As we gained altitude to get a wider view of the area, we hit the freezing temperature and the windows started to fog up, and this was August! That explained the low cloud layer!
It is estimated that the original ground plane was as much as 15 meters above the present level. Even at our altitude the apparent size of the crater was deceiving. To give an idea of the scale, if I stood on the crest of the rim and threw a baseball as hard as I could toward the lake (and I used to make it to home plate from center field!), the ball would only make it two thirds of the way to the water! During my ground expedition to the crater a few years later, I actually did try and throw a rock into the water from the top of the crater rim. The rock maybe got a third of the way down to the water!!
The clarity of the water in the Pingualuit Crater was tested with a Secchi disc and has been documented to have a visibility of over 30 metres! The lake is not connected to the regional drainage system. It is supplied solely by precipitation and is very poor in nutrients. The Arctic Char in the lake are totally isolated from the local lakes and have responded to the consequent malnutrition by evolving oversized heads and thin bodies. In addition to illustrating the clear blue colour of the water, this image shows a “gully” eroded through the crater rim. A hypothesis of how the fish originally “got into” the crater’s lake is possibly explained by this gully. During the times of glacial melt, the water level in the crater was higher than it is today and drained through this gully. Arctic Char may have swum upstream in the creek through this gully and into the crater from one of the local lakes.
Compare this image with my image of the Barringer Crater and note the difference in the relative size of the craters. I took the images for each crater from approximately the same altitude and distance. The Barringer Crater is 1.19 km diameter and Pingualuit is 3.44 km diameter.
I just could not get enough of this crater. My video and still cameras were constantly active. I was fortunate to have a fellow pilot share the flying chores as I was only looking out at the crater! Documenting this crater was the main purpose of our trip up to northern Quebec.
Our fuel endurance allowed a maximum of 45 minute hang time over the crater. At the 44 minute and 59 second point we headed north-west to the Hudson Strait and the village of Salluit. We picked Salluit to land, refuel and to spend the night because it was safely in range of our remaining fuel. Also, it is one of the most northern villages in Quebec and we wanted to claim that we had actually landed there.
Here I am at Salluit refuelling the aircraft from one of the containers of aviation fuel that we transported with us. Without this “fuel stop” we would not have made it back to our point of departure, Kuujjuaq, as aviation fuel was not available north of Kuujjuaq. It is August and yes that is snow in the background!
And we did land with the predicted fuel safety margin. Flying a small airplane in the remote north of Canada requires substantial planning to ensure survival in the event of an “emergency”. In addition to planning in advance for fuel stops, we had more than the recommended amount of survival gear on board. But, when we passed the tree line I thought, “Well, how are we make a fire now with no wood?” Being a member of the Civil Air Search and Rescue organization. I am well aware of the difficulties that are encountered while searching for missing aircraft. In that mode, I ensured that our flight plans were well documented by the authorities. Not only did we precisely follow these flight plans, we made frequent position reports to the “high flying” aircraft far overhead.
Ground Exploration of the Pingualuit Crater by Charles O’Dale – August 2008
|Mr. Eric Kujala, a fellow RASC member, contacted me after he had read my original article (above) to inquire about my future exploration plans to the crater. At our first meeting we agreed to an informal “crater exploration” partnership with our primary desire to eventually expedite a ground exploration project to the Pingualuit Impact Crater. We investigated many avenues for access to the structure, even including walking the 90 km to the crater from Kangiqsujuaq (formerly Wakeham Bay). During the three years that we were investigating ways to get to Pingualuit, we explored many other impact craters. We did this on the ground using Eric’s canoe and, from the air using my airplane.
All our planning efforts changed with the November 2007 opening of the Parc National des Pingualuit. An airstrip was constructed at the crater which meant that we could make it to the crater by simply chartering an airplane from Kuujjuaq. I could not use my airplane for the final leg of this trip due to the weight and fuel constraints caused by the extra bulk of our camping gear. Besides, general aviation aircraft are not allowed to land in the park.
So in August 2008, after a round-about trip flying in my airplane from Ottawa to Kuujjuaq, then air-chartering via Kangiqsujuaq, we finally arrived at our destination, the Pingualuit Impact Crater. We traveled there via a chartered twin otter. We spent four days of exploration there living our dream.
Our first day at the crater consisted of setting up our camp site and doing a reconnaissance of the local terrain. It was too late in the day for a productive trip up to the crater. I tucked my tent behind a fairly large rock for shelter from the gusting winds (they were steady at 20 knots+). From my camp site the rim of the crater was visible as a small hill in the distance, illustrated in the image. The rocky terrain we had to traverse to the crater is very obvious in the picture. The temperatures here in August ranged from just freezing at night to a pleasant 20° C during the day. The water in my canteen formed ice crystals during the nights.
Early in the morning of the second day we proceeded up to the crater rim. The walking was extremely difficult with the ground in the area covered in layers with large rock fragments. The rim rose continuously during the 2.5 km walk from Lac Laflamme to the crater. We had to climb over two ridges before reaching the steep slope of the rim itself. The outside rim is covered with a jumbled heap of large fragments of granite blocks. This made it a challenge to safely climb up the 100m, 10° slope. These rock fragments cover the ground completely for a distance of nearly 5 km beyond the rim.
After a climb of 100m up the 10° slope we finally made it to the top of the rim. In this picture you can see two very happy explorers savouring the moment, all our planning has finally come true!! The rim is so broad, that at its peak, we could not see the lake inside the crater nor the terrain immediately outside surrounding the rim. The lake within the crater only became visible when we climbed over the flat peak of the rim. From where we stood, it was over 3 km across to the opposite side of the rim. The rim is highest and widest at its north east position giving the crater a lopsided cup shape. On the rim it was perfectly silent, we could hear the waves breaking on the inner rim 150 m below us. The far rim is 3 km in the distance, a challenging hike!
The boulders on the slope are very unstable making it unsafe for a descent to the lake at this point. The distance to the water is very deceptive. It looked so close it seemed that you could easily throw a rock into the water from where we stood on the rim. I tried and didn’t even get close to hitting the water!
The hike around the crater took most of the day and I have to say it was not one of the easiest of hikes that I have experienced. There were frequent gullies that we had to traverse along the lip of the rim. Our Inuit guides were extremely helpful in showing us the various unique geological features of the crater. This included leading us to the only safe descent to the enclosed lake. Close to the water we found wild blue berries.
I personally made two trips to the crater during our four day visit. On the other two days I explored outside the rim documenting the effects of the impact on the local geology. The exposed bedrock of the Pingualuit Meteorite Crater’s target rock consists of a mélange of metamorphosed, Archean plutonic rocks cut by rare basic dykes (Shoemaker, 1962).
About 5 km east of the crater I was fortunate to find a large example of highly shocked and melted impactite (illustrated image below – the caribou antler placed on the impactite is for scale). Pingualuit impactite contains enrichments in Ir, Ni, Co and Cr suggesting that the impacting body was chondritic in composition with siderophile element enrichment (Grieve 1991). Pingualuit impactite originated from dike bodies in the crater rim, was eroded and carried 3-4 km north of the crater by water action (Grieve 2006).
About 5 km east of the crater I was fortunate to find a large example of highly shocked and melted impactite (illustrated image left – the caribou antler placed on the impactite is for scale). Pingualuit impactite contains enrichments in Ir, Ni, Co and Cr suggesting that the impacting body was chondritic in composition with siderophile element enrichment (Grieve 1991). Pingualuit impactite originated from dike bodies in the crater rim, was eroded and carried 3-4 km north of the crater by water action (Grieve 2006).
Impact melt rocks from New Quebec crater
Abstract— Approximately 1500 g of float samples of impact melt rocks have been recovered from gravel deposits ∼4 km north and northeast of the rim of the 3.4 km diameter New Quebec Crater (61°17′N; 73°40′W) in northern Quebec, Canada. Previously, only two small samples of impact melt rocks were known. The newly recovered samples have cryptocrystalline to microcrystalline matrices with microlites of andesine and pigeonite. Mineral clasts of quartz and feldspar occur and, in some cases, show shock metamorphic features. The melt rocks have a normative mineralogy corresponding to ∼70% quartz, orthoclase and albite and are compositionally similar. Their major element composition can be modeled as a mix of granitic gneisses that make up the target rocks. The melt rocks show enrichments, however, in Cr (21 ppm), Co (9 ppm), Ni (12 ppm) and Ir (1.5 ppb) over the target rocks. Interelement ratios suggest a chondritic impacting body, although they do not define a specific type. Assuming a C-1 chondrite, the impact melt rocks average ∼2% meteoritic contamination. Stepwise 40Ar-39Ar dating using a laser on three chips from three samples give integrated ages of 0.6–2.5 Ma. From the best plateau ages, the age of the New Quebec impact is taken to be 1.4 ± 0.1 Ma, which places it before the first major northern hemisphere continental glaciation of the Pleistocene. A number of considerations suggest that the impact melt rocks were originally deposited in fractures in the crater wall and later transported to their discovery site by glacial ice and melt water (Grieve et al, 1991).
Being an amateur rock hound, I kept searching for any shattercones that would have been created by the impact, unfortunately without success.
In addition I experienced a close encounter with a few caribou and found an old Inuit campsite. It was impossible to guess the age of this camp site, it could have been here undisturbed for tens or even many hundreds of years! I had a very spiritual feeling gazing at this old camp-site trying to picture the family that survived here. Having had Arctic survival training with the military, and now again experiencing this type of desolate terrain, I stated to our Inuit guides how respectful I am toward their ancestors in that they could successfully support and feed a family in this type of geography.
|I also have the utmost respect for past exploration teams who, day after day for months, walked to the crater rim from their base camp for their research. The two trips I made to the top of the crater rim totally exhausted me! Our exploration of the Pingualuit Impact Crater and local area was very rewarding, an experience Eric and I will treasure the rest of our lives (O’Dale 2009).|
Slickenside is a smoothly polished surface caused by frictional movement between rocks along the two sides of a fault. Slickensides are naturally polished rock surfaces that occur when the rocks along a fault rub against each other, making their surfaces smoothed, lineated, and grooved. Slickensides are characterized by a diagnostic unidirectional step-like pattern that actually allows investigation of the sense of movement on fractures (Passchier and Trouw 1996). In contrast, striations on shatter cone surfaces are distinctly rounded (Nicolaysen and Reimold, 1999). Furthermore, could the sudden fractures in fault lines be caused by a cosmic impact creating “impact slickensides”?
During my exploration of the Pingualuit Crater, I specifically searched for any evidence of shatter cones. At the time I documented geologic “striations” in some rocks that were not shatter cones. These formations that I could not identify are documented in the images below.
I am suggesting that the impact at Pingualuit caused sudden fractures along local fault lines creating these possible slickensides. Further I am suggesting that slickensides may be an indicator of a cosmic impact.
“Our Aerial Expedition” by Terry Peters – August 2001
|We were off the ground at Kuujjuaq around 3PM with the Chubb Crater, a major attraction (for us!) about 250nm (roughly two hours) away. The visibility was unlimited, except that there was an overcast at around 3000 feet, with only occasional breaks for sunshine to show through. The barrenness of the territory was cause for some reflection. Certainly not a place to be stranded. Caribou tracks were visible all over the place, but not a caribou to be seen. This was about the only disappointment of the whole trip. We never did see a caribou herd.
From at least 30 miles we could see the rim of the crater on the horizon. The crater itself was a most impressive sight. It was first recognized as an impact structure in 1950. It’s relatively young – only 1.4 million years and almost perfectly circular, 3.4km in diameter with a raised rim up to 163 meters above the lake surface in the central flooded depression. The lake is 252 meters deep. We must have spent nearly 45 minutes circling it to take photos and video before leaving for Salluit, about 40 min. away. It would have been nice to have landed and visited it on foot but this was a pretty unfriendly and desolate place. Perhaps another time on floats or with large tundra tires!! (we then flew direct to Salluit – author)
Salluit (Inuit word for “skinny people”) is situated on a bay surrounded by hills and overlooking Hudson Straight. It’s hard for me to imagine living in such isolation, but the Inuit have lived here for centuries. The airport is relatively new (less than 15 years) so until very recently access was via small floatplanes in the summer or by larger ski-equipped ones in the winter. Ships still bring in supplies during the relatively short ice-free period in the summer. We walked down into the settlement (2 miles or so from the airport – elevation 740ft) on a densely packed gravel road, designed to hold up against the permafrost. The houses are all square, two stories high, shipped in by boat (there are certainly no building materials in this part of the world). They’re placed on shafts that reach below the permafrost. The walls of the second stories are all painted bright blue, green or red, with the ground floor generally white. And all the gravel streets are laid out in neat rows. Would have loved to take pictures of children playing with husky puppies and mothers in Inuit coats carrying babies on their backs, but that would have been rude. It was obvious we were visitors of course and most gave us friendly waves and smiles. Some just ignored us! Several small boats with outboard engines were pulled up on the shore. The economy is based on seal, beluga whale and walrus hunting. A mine 50km from Salluit, at Deception Bay, is a significant player in the local economy. There were three or four pickups, used to carry supplies between the village and the airport. We saw a few 4-wheel dune buggies and one or two mopeds and small motorcycles. About 1030 people live in the village. Some houses are being built a mile or so inland since there is no more room to expand the present housing area.The uphill walk back to the airport gave us more than enough exercise at the end of a long day. Even though it was about 2°C, (and this is August 27th!) we had to take our parkas off! Accommodation in these isolated communities is scarce and very expensive, so we had decided earlier that we would tent. We put it up on the crest of a hill just below where the aircraft was parked on the ramp. The wind snapped away at the tent all night. It rained most of the time but not enough to get rid of the snow patches nearby. In the morning we were fogged in. We used the time to fold up the tent and refuel. Fuel is available at isolated communities but you have to buy a whole 45 gal. drum for $500 (2001 dollars!). Knowing this, we carried an extra 20 gals. with us in 5 gal. containers.
“Our Ground Expedition” by Eric Kujala – August 2008