AMHERST, Mass. - University of Massachusetts climate researcher Julie Brigham-Grette, department of geosciences, has just returned from a month-long, international expedition to a remote lake in Eastern Siberia – the site of an ancient meteorite crater. The crew camped in the middle of frozen Elgygytgyn Lake, drilled through seven feet of ice, then dropped specialized coring equipment attached to steel cables through 175 feet of water to collect several 10-foot-long cylinders, called "cores," of layered sediment from the lake bottom. Scientists hope that the sediments will give them clues about the region’s past climate since the area was hit by a meteorite 3.6 million years ago, Brigham-Grette said. This is a pilot project to determine whether it would be worth a much larger effort to collect sediments down to the original crater floor.
According to Brigham-Grette, the crater is 15 ½ miles wide, rim-to-rim, making it among the largest-known impact craters in the world. Although the Earth is dotted with impact craters, this particular site is one of the few known on the Arctic tundra, making it "absolutely unique in terms of offering a climate archive," said Brigham-Grette.
Brigham-Grette led the six-person research team, which included scientists from the Alfred Wegener Institute (AWI) in Potsdam, Germany, the University of Alaska at Fairbanks, and the Northeast Interdisciplinary Scientific Research Center in Magadan, Russia. The expedition was primarily funded with a $77,000 grant from the National Science Foundation’s office of polar programs, with additional funding from UMass and AWI.
The group reached the site by flying from Anchorage, Alaska, to Magadan, Russia. Once in Russia, they chartered a cargo plane for the first leg of the trip to the remote mining town of Pevek, then hired two Aeroflot helicopters to transport the scientists and some 4,000 pounds of gear to the lake, 155 miles away. Working conditions were challenging, Brigham-Grette said, with temperatures hovering at -25 Celsius (-13 F.) during the night, and -10 Celsius (14 F.) during daylight hours. The crew relied on high-tech insulated clothing and sleeping bags to stay warm. Because of the potential for high winds, tents were secured to the ice with ice screws similar to those used by mountain climbers, Brigham-Grette said.
Scientists plan to split the cores of silt and clay later this summer, and begin searching for microscopic clues, including pollen from vegetation, "which tells us where and when different kinds of plants grew, and that tells us a great deal about changes in the past climate," Brigham-Grette said. Researchers will also examine the microscopic fossils of a type of algae called diatoms, as well as ostracodes – microscopic crustaceans that build a calcium carbonate shell. "The chemistry of these microfossils can tell scientists about water chemistry and water temperature, which are linked with climate," Brigham-Grette said. The cores collected by the team reached about 40 feet into the lake bottom, and are likely to offer a climate archive going back 30,000 to 40,000 years, she said.